TW201900903A - Film forming device and film forming method - Google Patents

Abstract

The film-forming device according to one embodiment of the present invention has: a chamber 21 electrically connected to a grounding potential; a target TG disposed in the chamber; a power supply section 32 that supplies high-frequency power to the target; gas supply sections 23, 24 that supply a gas to the inside of the chamber; a substrate holding insulating section 25b, which is disposed in the chamber, and which holds a substrate SB by having the substrate face the target; a conductive supporting section 42 that supports the substrate holding insulating section; and a first insulating member 53 disposed between the conductive supporting section and the chamber. The conductive supporting section is electrically floating from the chamber due to the first insulating member, the substrate is held by the substrate holding insulating section when an outer peripheral section of the substrate comes into contact with the substrate holding insulating section, the substrate is electrically floating from the conductive supporting section, and the substrate holding insulating section does not overlap a center section of the substrate in plan view.

Description

   Film forming device and film forming method   

The invention relates to a film forming device and a film forming method.

As a film structure having a substrate, a conductive film formed on the substrate, and a piezoelectric film formed on the conductive film, a conductive film having a substrate, a platinum-containing film formed on the substrate, and a film formed on the substrate are known A film structure of a piezoelectric film containing lead zirconate (PZT) on a conductive film.

In International Publication No. 2016/009698 (Patent Document 1), it is disclosed that a ferroelectric ceramic is provided with a Pb (Zr _1-A Ti _A ) O ₃ film and is formed on the Pb (Zr _1-A Ti _A ) O ₃ film of _{Pb (Zr 1-x Ti x} ) O 3 film, a, and x satisfies 0 ≦ a ≦ 0.1 and 0.1 <x art <of 1.

Japanese Patent Laid-Open No. 2014-84494 (Patent Document 2) discloses that YSZ (8% Y ₂ O ₃ + 92% ZrO ₂ ), CeO ₂ , and LaSrCoO _{3 are} laminated in advance on a silicon substrate (Si) A technique of forming a PZT (lead titanate zirconate) thin film on a buffer layer formed by a film. In particular, Patent Document 2 discloses a technique in which LaSrCoO ₃ (LSCO) rotates a 45 ° lattice on other films.

Non-Patent Document 1 discloses that a buffer layer formed by sequentially stacking YSZ, CeO ₂ , La _0.5 Sr _0.5 CoO ₃ (LSCO), and SrRuO ₃ (SRO) on a silicon substrate is formed on the buffer layer. The technology of forming c-axis aligned 0.06Pb (Mn _1/3 , Nb _2/3 ) O ₃ -0.94Pb (Zr _0.5 Ti _0.5 ) O ₃ (PMnN-PZT) epitaxial thin film. Non-Patent Document 1 discloses a technique in which the lattice of PMnN-PZT rotates silicon by 45 ° in the in-plane direction.

Non-Patent Document 2 discloses that the relative dielectric constant of PbTiO ₃ bred by a flux method using a magnesium oxide single crystal crucible at room temperature is 150, which is the relative dielectric constant of pure PbTiO ₃ single crystal 1.5 times the constant technology.

In a piezoelectric film containing lead zirconate titanate, when the quality of the piezoelectric film, such as crystallinity, is not good, the piezoelectric characteristics of the piezoelectric film will be reduced. On the other hand, when the quality of the piezoelectric film, such as crystallinity, is good, the piezoelectric characteristics of the piezoelectric film are improved, and the relative dielectric constant of the piezoelectric film does not become small, for example, when the piezoelectric film is used as a pressure sensitive When the sensor is used, the detection sensitivity of the pressure sensor may be reduced due to, for example, an increase in the capacity of the pressure sensor, and the design of the detection circuit of the pressure sensor may become difficult.

However, it has been difficult to form such a piezoelectric film of lead titanate zirconate with good crystallinity and other good quality using a conventional film forming apparatus.

    [Prior Technical Literature]    

[Patent Literature 1] International Publication No. 2016/009698

[Patent Document 2] Japanese Unexamined Patent Publication No. 2014-84494

[Non-Patent Document 1] S. Yoshida et al., "Fabrication and characterization of large figure-of-merit epitaxial PMnN-PZT / Si transducer for piezoelectric MEMS sensors", Sensors and Actuators A 239 (2016) 201-208

[Non-Patent Document 2] Xiao Zhou text, 1 other person, "Cultivation and Evaluation of PbTiO ₃ Single Crystal Based on MgO Single Crystal Crucible", Journal of the Kiln Industry Association, 1987, No. 95, No. 11, p.1053 -1058

One aspect of the present invention is to provide a film forming apparatus or film forming method for forming a film with good crystallinity.

Hereinafter, various aspects of the present invention will be described.

[1] A film forming apparatus characterized by having a vacuum chamber electrically connected to a ground potential, a target arranged in the vacuum chamber, a power supply unit that supplies high-frequency power to the target, and gas supply to the vacuum chamber A gas supply part, an insulating substrate holding part arranged in the vacuum chamber to hold the substrate opposite to the target, a conductive supporting part supporting the insulating substrate holding part, and the conductive supporting part A first insulating member between the vacuum chambers; the conductive support portion is in an electrically floating state to the vacuum chamber by the first insulating member, and is in contact with the insulating substrate holding portion through the outer peripheral portion of the substrate, The substrate is held by the insulating substrate holding portion, the substrate is in an electrically floating state to the conductive support portion, and the insulating substrate holding portion does not overlap the central portion of the substrate in plan view.

According to the film forming apparatus of [1] above, the insulating substrate holding portion is supported by the conductive supporting portion in an electrically floating state to the vacuum chamber, and the substrate held by the insulating substrate holding portion is electrically connected to the conductive supporting portion In the floating state, the electric charge accumulated in the substrate during film formation does not escape to the ground potential. By this, a large amount of electric charge can be accumulated in the substrate, and as a result, a film with good crystallinity can be formed.

[2] The film-forming apparatus according to [1] above, which has a conductive anti-adhesion plate disposed between the target and the substrate and located within a distance of 30 mm from the substrate, the conductive anti-adhesion plate facing the foregoing The vacuum chamber is in an electrically floating state.

According to the film forming apparatus of [2] above, even if the conductive anti-adhesion plate is disposed on the substrate within a distance of 30 mm, by making the conductive anti-adhesion plate electrically floating to the vacuum chamber, it can be accumulated during film formation The charge on the substrate will not escape to the ground potential.

[3] The film forming apparatus as described in [2] above, wherein the conductive anti-adhesion plate is water-cooled.

[4] The film forming apparatus according to [2] or [3] above, which includes a second insulating member disposed between the vacuum chamber and the conductive anti-adhesion plate.

[5] The film forming apparatus according to any one of the above [1] to [4], wherein the contact area of the substrate and the insulating substrate holding portion is reduced to 20 mm ² or less.

According to the film forming apparatus of the aforementioned [4], by making the contact area of the substrate and the insulating substrate holding portion 20 mm ² or less, thermal insulation and electrical insulation to the substrate can be obtained at the same time.

[6] The film forming apparatus according to any one of the above [1] to [5], wherein the corner of the insulating substrate holding portion has a curved surface.

[7] The film forming apparatus according to any one of the above [1] to [6], wherein the conductive support portion includes a first conductive member supporting the insulating substrate holding portion, and the first conductive member is The first axis is provided as a center and can rotate integrally with the insulating substrate holding portion, and has a third insulating member disposed between the first conductive member and the insulating substrate holding portion, and the film forming apparatus, Furthermore, it has a rotation driving section that rotatably drives the first conductive member.

[8] The film forming apparatus according to any one of the above [1] to [6], wherein the conductive support portion includes a second conductive member that supports the insulating substrate holding portion, and the second conductive member is The second axis is centered and can be rotated integrally with the insulating substrate holding portion; the first insulating member is interposed between the vacuum chamber and the second conductive member, and the second conductive member is electrically floating In this state, the film forming apparatus further includes a rotation driving section that rotationally drives the second conductive member.

[9] The film-forming apparatus according to [7] above, which includes a substrate heating portion that heats the substrate, the third insulating member, a plan view having a surrounding portion surrounding the substrate, and the insulating substrate holding portion, having a plan view A plurality of protrusions each protruding from the surrounding portion toward the center side of the substrate, and the insulating substrate holding portion holds the substrate in a state where the outer peripheral portion of the substrate is in contact with each of the plurality of protrusions.

[10] The film forming apparatus according to any one of the above [1] to [9], which has a target holding portion that holds the target in the vacuum chamber, and a magnetic field applying portion that applies a magnetic field to the target; The horizontal magnetic field on the surface of the aforementioned target is 140-220G.

[11] The film-forming apparatus according to [10] above, wherein the surface of the target is along the surface of the target before the magnetic field.

[12] The film forming apparatus according to any one of [1] to [11], wherein the film forming apparatus forms titanium zirconium on the surface of the substrate by sputtering the surface of the target containing lead titanate zirconate Lead acid film.

[13] The film forming apparatus according to any one of the above [1] to [12], wherein the film forming apparatus is applied to the substrate by sputtering in the vacuum chamber on the target upper surface which is arranged to face the lower surface of the substrate The film is formed below.

[14] A film forming method characterized in that, in a vacuum chamber electrically connected to a ground potential, the outer peripheral portion of the substrate is in contact with an insulating substrate holding portion, and the insulating substrate holding portion holds the substrate by A film is formed on the surface of the substrate by sputtering the surface of the target in the vacuum chamber, the insulating substrate holding portion is supported by a conductive support portion in an electrically floating state to the vacuum chamber, and the substrate supports the conductive The portion is in an electrically floating state, and the plan view of the insulating substrate holding portion does not overlap with the central portion of the substrate.

[15] The film forming method of the aforementioned [14], wherein the conductive anti-adhesion plate is disposed between the target and the substrate, the conductive anti-adhesion plate is located within a distance of 30 mm from the substrate, and the conductive The attachment plate is in an electrically floating state to the aforementioned vacuum chamber.

[16] The film forming method as described in [14] above, wherein the conductive anti-adhesion plate is water-cooled.

[17] The film-forming method according to any one of the aforementioned [14] to [16], wherein the contact area of the substrate and the insulating substrate holding portion is 20 mm ² or less.

[18] The film-forming method according to any one of the above [14] to [17], wherein a magnetic field is applied to the target by a magnetic field applying section, and a high-frequency power is supplied to the target by an electric power supply section, By sputtering the surface of the target to form the film on the surface of the substrate, the horizontal magnetic field on the surface of the target to which the magnetic field is applied is 140 to 220G.

[19] The film forming method according to the aforementioned [18], wherein the magnetic field on the surface of the target is along the surface of the target.

[20] The film forming method according to any one of the above [14] to [19], wherein the target contains lead titanate zirconate, and the surface containing the lead titanium zirconate is formed on the surface of the substrate by sputtering the surface of the target The aforementioned film.

[21] The film forming method according to the aforementioned [20], wherein the substrate includes: a silicon substrate including a main surface composed of a (100) plane, formed on the main surface, has a cubic crystal structure, and includes (100) a first film of an aligned zirconia film, and a first conductive film formed on the first film, having a cubic crystal structure, and including (100) an aligned platinum film; the zirconia film, Aligned along the <100> direction of the main surface of the zirconia film parallel to the <100> direction of the main surface of the silicon substrate; the platinum film along the main surface of the platinum film The <100> direction is aligned parallel to the <100> direction along the main surface of the silicon substrate; by sputtering the surface of the target, a crystal structure having a tetragonal crystal is formed on the first conductive film And the first piezoelectric film including the (001) aligned first lead zirconate titanate film, the first lead zirconate titanate film has a lead titanate zirconate represented by the following general formula (chemical formula 1) the first composite _{oxide, Pb (Zr 1-x Ti} x) O 3 ‧‧‧ ( chemical formula 1) the first lead zirconate titanate film, along The <100> direction of the principal surface of the first titanium film of lead zirconate, parallel manner along the <100> direction of the main surface of the silicon substrate alignment; the x satisfies 0.32 ≦ x ≦ 0.52.

[22] The film forming method according to any one of the above [14] to [21], wherein a film is formed on the underside of the substrate by sputtering in the vacuum chamber on the target upper surface that is opposed to the undersurface of the substrate.

By applying one aspect of the present invention, it is possible to provide a film forming apparatus or method for forming a film with good crystallinity.

10‧‧‧membrane structure

11‧‧‧ substrate

11a‧‧‧Top

12‧‧‧Alignment film

12a‧‧‧zirconia film

13, 18‧‧‧ conductive film

13a‧‧‧Platinum film

14, 17f‧‧‧ film

14a‧‧‧SRO membrane

15, 16, 17‧‧‧ Piezoelectric film

15a, 16a, 17a‧‧‧‧Titanate zirconate film

16g, 17g

20‧‧‧film-forming device

21‧‧‧Vacuum chamber

21a‧‧‧Bottom part

21b, 21e‧‧‧side plate

21c, 21f

21d‧‧‧Cover

22‧‧‧Vacuum exhaust department

23, 24‧‧‧ gas supply department

23a, 24a‧‧‧Flow controller

23b, 24b‧‧‧ gas supply pipe

25‧‧‧Substrate holding section

25a‧‧‧Insulation surrounding part

25b‧‧‧Projection

25c‧‧‧Conductive surrounding part

25d‧‧‧step difference

25b1‧‧‧ corner

26‧‧‧Support

27‧‧‧rotation drive

27a‧‧‧Motor

27b‧‧‧Belt

27c‧‧‧Pulley

27d‧‧‧rotation axis

28‧‧‧Substrate heating section

29‧‧‧Anti-adhesion board

29a‧‧‧cooling tube

31‧‧‧Target Holder

32‧‧‧Power Supply Department

32a‧‧‧High frequency power supply

32b‧‧‧integrator

33‧‧‧V _DC Control Department

34‧‧‧Magnet

35‧‧‧Magnet Rotation Drive

41, 42, 45, 46, 47 ‧‧‧ conductive members

41a, 42a, 45a ‧‧‧ base

41b, 42b, 45b ‧‧‧ shaft

41c, 42c, 45c

43、56‧‧‧screw

44‧‧‧Slip ring

51, 52, 53, 54, 55

BP1‧‧‧backing plate

CE1‧‧‧Seal Department

CN1‧‧‧Center

CP1‧‧‧ ferroelectric capacitor

EP‧‧‧End

OP1, OP2, OP3‧‧‧ opening

P1‧‧‧polar component

RA1‧‧‧rotation axis

SB‧‧‧Substrate

SP‧‧‧Starting point

TG‧‧‧Target

TM1‧‧‧Target

FIG. 1 is a cross-sectional view of a film structure of an embodiment.

2 is a cross-sectional view of the film structure in the case where the film structure of the embodiment has a conductive film as an upper electrode.

3 is a cross-sectional view of the film structure when the substrate and the alignment film are removed from the film structure shown in FIG. 2.

4 is a cross-sectional view of another example of the membrane structure of the embodiment.

FIG. 5 is a diagram schematically showing a cross-sectional structure of two piezoelectric films included in the film structure of the embodiment.

FIG. 6 is a diagram schematically showing the electric field dependence of the polarization of the piezoelectric film included in the film structure of the embodiment.

7 is a diagram illustrating the state of film epitaxial growth of each layer included in the film structure of the embodiment.

FIG. 8 is a cross-sectional view schematically showing a film forming apparatus of an embodiment.

FIG. 9 is a cross-sectional view schematically showing a film-forming apparatus of an embodiment.

FIG. 10 (A) is a plan view of a substrate holding portion included in the film forming apparatus of the embodiment, and FIGS. 10 (B) to (D) are diagrams showing the shape of the protrusion 25b shown in FIG.

FIG. 11 is a cross-sectional view in a manufacturing step of a film structure of an embodiment.

FIG. 12 is a cross-sectional view in the manufacturing steps of the film structure of the embodiment.

Fig. 13 is a cross-sectional view in a manufacturing step of a film structure of an embodiment.

Fig. 14 is a cross-sectional view in a manufacturing step of a film structure of an embodiment.

Fig. 15 is a cross-sectional view of a membrane structure according to a modification of the embodiment.

16 is a diagram showing an example of the θ-2θ spectrum of the film structure of Example 1 according to the XRD method.

17 is a diagram showing an example of the θ-2θ spectrum of the film structure of Example 1 according to the XRD method.

18 is a diagram showing an example of the θ-2θ spectrum of the film structure of Comparative Example 1 according to the XRD method.

19 is a diagram showing an example of the θ-2θ spectrum of the film structure of Comparative Example 1 according to the XRD method.

20 is a diagram showing an example of the pole figure according to the XRD method of the film structure of Example 1. FIG.

21 is a diagram showing an example of a pole figure according to the XRD method of the film structure of Example 1. FIG.

22 is a diagram showing an example of a pole figure according to the XRD method of the film structure of Example 1. FIG.

23 is a diagram showing an example of the pole figure according to the XRD method of the film structure of Example 1. FIG.

24 is a diagram showing the diffraction angle 2θ ₀₀₄ of the respective X-ray diffraction patterns of the film structures formed on the 17 wafers of Example 1. FIG.

25 is a diagram showing the diffraction angle 2θ ₀₀₄ of the respective X-ray diffraction patterns of the film structures formed on the 12 wafers of Example 1. FIG.

26 is a graph showing the voltage dependence of the polarizing of the film structure of Example 1. FIG.

FIG. 27 is a graph showing the voltage dependence of the polarizing of the film structure of Comparative Example 1. FIG.

28 is a graph showing the voltage dependence of the polarizing of the film structure of Example 2. FIG.

29 is a graph showing the voltage dependence of the polarizing of the film structure of Example 3. FIG.

30 is a graph showing the voltage dependence of the polarizing of the film structure of Example 4. FIG.

31 is a graph showing the voltage dependence of the polarizing of the film structure of Example 5. FIG.

32 is a table showing the measurement results of the film forming conditions of Example 1, Example 6 to Example 8, Comparative Example 1 and Comparative Example 2, the diffraction angle 2θ _{004 of} PZT, and the relative dielectric constant ε _r .

33 is a diagram showing an example of the θ-2θ spectrum of the film structure of Example 6 according to the XRD method.

34 is a diagram showing an example of the θ-2θ spectrum of the film structure of Example 7 according to the XRD method.

35 is a diagram showing an example of the θ-2θ spectrum of the film structure of Example 8 according to the XRD method.

36 is a graph showing the voltage dependence of the polarizing of the film structure of Comparative Example 2. FIG.

37 is a graph showing the voltage dependence of the polarizing of the film structure of Example 6. FIG.

38 is a graph showing the voltage dependence of the polarizing of the film structure of Example 7. FIG.

39 is a graph showing the voltage dependence of the polarizing of the film structure of Example 8. FIG.

40 is a graph showing the voltage dependence of the polarizing of the film structure of Example 9. FIG.

41 is a graph showing the voltage dependence of the polarizing of the film structure of Example 10. FIG.

Hereinafter, the embodiments and embodiments of the present invention will be described in detail using drawings. However, the present invention is not limited to the following description, and without changing the gist and scope of the present invention, its form or details can be changed in various ways, which should be easily understood by those familiar with the art Scope. Therefore, the present invention is not limited to be interpreted as the contents and examples of the embodiments described below.

In addition, the drawings can make the description more clear. Compared with the implementation, the width, thickness, shape, etc. of each part are also represented in a model. After all, it is only an example, and is not used to limit the invention. Explanation.

In this specification and the drawings, the same elements as those described above will be given the same symbols, and detailed descriptions will be omitted as appropriate.

Furthermore, in the drawings used in the embodiment, the hatching (net line) for distinguishing the structure may be omitted depending on the drawing.

In addition, in the following embodiment mode, when the range is displayed as A to B, unless otherwise specified, it means A or more and B or less.

    (Implementation type)         <Membrane structure>    

First, a film structure of an embodiment of an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a film structure of an embodiment. 2 is a cross-sectional view of the film structure in the case where the film structure of the embodiment has a conductive film as an upper electrode. 3 is a cross-sectional view of the film structure when the substrate and the alignment film are removed from the film structure shown in FIG. 2. 4 is a cross-sectional view of another example of the membrane structure of the embodiment.

As shown in FIG. 1, the film structure 10 of the present embodiment has a substrate 11, an alignment film 12, a conductive film 13, a film 14, and a piezoelectric film 15. The alignment film 12 is formed on the substrate 11. The conductive film 13 is formed on the alignment film 12. The film 14 is formed on the conductive film 13. The piezoelectric film 15 is formed on the film 14.

Furthermore, as shown in FIG. 2, the film structure 10 of the present embodiment may also have a conductive film 18. The conductive film 18 is formed on the piezoelectric film 15. At this time, the conductive film 13 is a conductive film as a lower electrode, and the conductive film 18 is a conductive film as an upper electrode. In addition, as shown in FIG. 3, the film structure 10 of the present embodiment may not include the substrate 11 (see FIG. 2) and the alignment film 12 (see FIG. 2), but only have the conductive film 13 and the film as the lower electrode. 14. The piezoelectric film 15 and the conductive film 18 as an upper electrode.

In addition, as shown in FIG. 4, the film structure 10 of the present embodiment may include only the substrate 11, the alignment film 12, and the conductive film 13. In this case, the film structure 10 can be used as an electrode substrate for forming the piezoelectric film 15, epitaxial growth can be performed on the conductive film 13, and the piezoelectric film 15 having good piezoelectric characteristics can be easily formed.

The substrate 11 is a silicon substrate made of silicon (Si) single crystal. The substrate 11 as a silicon substrate includes an upper surface 11a of a main surface composed of (100) planes. The alignment film 12 is formed on the upper surface 11a, has a cubic crystal structure, and contains (100) aligned zirconia. The conductive film 13 has a cubic crystal structure and contains (100) aligned platinum. As a result, when the piezoelectric film 15 includes a composite oxide having a perovskite structure, the piezoelectric film 15 on the substrate 11 can be (001) aligned with a square crystal or The (100) alignment indicated by the quasi-cubic crystal.

Here, the alignment film 12 is (100) alignment, which means that the (100) plane of the alignment film 12 having a cubic crystal structure is along the main surface of the silicon substrate 11 as the (100) plane The upper surface 11a is preferably an upper surface 11a formed parallel to the (100) surface of the substrate 11 of the silicon substrate. In addition, the (100) plane of the alignment film 12 is parallel to the upper surface 11a of the (100) surface of the substrate 11 means that not only the (100) plane of the alignment film 12 is completely parallel to the upper surface 11a of the substrate 11, but also includes When the angle between the surface completely parallel to the upper surface 11a of the substrate 11 and the (100) surface of the alignment film 12 is 20 ° or less. In addition, not only the alignment film 12 but also the alignment of the films of other layers are the same.

Alternatively, instead of the alignment film 12 composed of a single-layer film, the alignment film 12 may be formed on the substrate 11 instead of the alignment film 12 composed of a laminated film.

Preferably, the alignment film 12 is epitaxially grown on the upper surface 11 a of the substrate 11, and the conductive film 13 is epitaxially grown on the alignment film 12. Accordingly, when the piezoelectric film 15 includes a composite oxide having a perovskite structure, the piezoelectric film 15 can be epitaxially grown on the conductive film 13.

Here, when two directions orthogonal to each other in the upper surface 11a as the main surface of the substrate 11 are taken as the X-axis direction and the Y-axis direction, and the direction perpendicular to the upper surface 11a is taken as the Z-axis direction, a certain film epitaxial growth , Means that the film is aligned in any of the X-axis direction, Y-axis direction, and Z-axis direction. In addition, the alignment direction in the appropriate upper surface 11a will be described using FIG. 7 described later.

The film 14 is represented by the following general formula (Chemical Formula 4), and includes a composite oxide represented by (100) alignment in a quasi-cubic crystal.

Sr (Ti _1-z Ru _z ) O ₃ ‧‧‧ (Chemical formula 4)

Here, z means that 0 ≦ z ≦ 1. In addition, in the following, Sr (Ti _1-z Ru _z ) O ₃ when z satisfies z = 0 is also called SrTiO ₃ , and Sr (Ti _1-z Ru when z satisfies 0 <z <1 _z ) O _{3 is} called STRO, and Sr (Ti _1-z Ru _z ) O ₃ when z satisfies z = 1 is also the case where SrRuO _{3 is} called SRO.

SRO has metal conductivity, and STO has semiconductivity or insulation. Therefore, the closer z is to 1, the more the conductivity of the film 14 is improved, and the film 14 can be used as a part of the lower electrode including the conductive film 13.

Here, when the film 14 is formed by a sputtering method, z preferably satisfies 0 ≦ z ≦ 0.4, and more preferably satisfies 0.05 ≦ z ≦ 0.2. When z exceeds 0.4, the composite oxide represented by the general formula (Chemical Formula 4) becomes powder and may not be sufficiently cured, making it difficult to produce a sputtering target.

On the other hand, when the film 14 is formed by a coating method such as a sol-gel method, it can be easily formed even if z> 0.4.

Represented by the aforementioned general formula (Chemical Formula 4), a composite oxide having a perovskite structure is represented by (100) alignment in a quasi-cubic crystal, which means an occasion as described below.

First, it includes a unit lattice arranged in 3 dimensions, a perovskite structure lattice represented by the general formula ABO ₃ , and it is considered that the unit lattice contains 1 atom A, 1 atom B, and 3 oxygen Atomic occasions.

In this case, the (100) alignment expressed by a pseudo-cubic crystal means that the unit lattice has a cubic crystal structure and is (100) aligned. At this time, let the length of one side of the unit lattice be the lattice constant a _c .

On the other hand, consider the case where the composite oxide having a perovskite structure is represented by the general formula (Chemical Formula 4) and has a rhombic crystal structure. Next, consider that the first lattice constant a _{o of the} three lattice constants of the orthorhombic crystal is approximately equal to 2 ^1/2 times the lattice constant a _c of the quasi-cubic crystal, and the three lattice constants of the orthorhombic crystal The second lattice constant b _{o among them} is approximately equal to twice the lattice constant a _c of the quasi-cubic crystal, and the third lattice constant c _o among the three lattice constants of the orthorhombic crystal is approximately equal to the pseudo-cubic crystal When the lattice constant a _c of the crystal is 2 ^1/2 times. In addition, in the specification of this case, the value V1 and the value V2 are approximately equal, which is the ratio of the difference between the index value V1 and the value V2, and is less than about 5% relative to the average of the value V1 and the value V2.

At this time, quasi-cubic crystals are expressed as (100) alignment, which means that rhombic crystals are expressed as (101) alignment or (020) alignment.

The film 14 is represented by the aforementioned general formula (Chemical Formula 4) and satisfies 0 ≦ z ≦ 1, so the lattice constant a _{c of the} pseudo-cubic crystal satisfies 0.390 nm ≦ a _c ≦ 0.393 nm, as explained using FIG. 7 described later , The film 14 can be aligned on the conductive film 13 in the form of a quasi-cubic crystal (100).

The piezoelectric film 15 and the interposer film 14 are formed on the conductive film 13 and have a tetragonal crystal structure, and include lead titanate-zirconate (PZT) as a (001) -aligned composite oxide. Alternatively, when the lead zirconate titanate (PZT) included in the piezoelectric film 15 includes a portion having a crystal structure of a tetragonal crystal and a portion having a crystal structure of a rhombohedral crystal, the piezoelectric film 15 interposes the film 14 It may be formed on the conductive film 13 and may include lead zirconate titanate (PZT) as a composite oxide represented by (100) alignment in a pseudo-cubic crystal.

The piezoelectric film 15 contains lead zirconate titanate (PZT), which means that the piezoelectric film 15 contains a composite oxide represented by the following general formula (Chemical Formula 5).

Pb (Zr _1-u Ti _u ) O ₃ ‧‧‧ (Chemical formula 5)

u satisfies 0 <u <1.

In addition, the piezoelectric film 15 has a crystal structure of a tetragonal crystal, and when it contains lead titanate zirconate of (001) orientation, in this embodiment, the piezoelectric film 15 according to the θ-2θ method using CuKα line The X-ray diffraction pattern, the square of lead zirconate titanate, the diffraction angle of the diffraction peak of the (004) plane is 2θ ₀₀₄ , 2θ ₀₀₄ satisfies the following formula (Equation 1).

2θ ₀₀₄ ≦ 96.5 ° ‧‧‧ (Equation 1)

By this, the interval of the (004) plane represented by the tetragonal crystal of lead titanate zirconate becomes longer. Or the piezoelectric film 15 has a tetragonal crystal structure, and the content ratio of (001) alignment (c-axis alignment) lead zirconate titanate can be compared with the piezoelectric film 15 having a crystal structure of tetragonal crystals, and ( 100) The content of lead (z-axis alignment) lead zirconate titanate is even greater. That is, the polarization directions of the plurality of crystal grains included in the piezoelectric film 15 can be aligned, so that the piezoelectric characteristics of the piezoelectric film 15 can be improved.

On the other hand, when the piezoelectric film 15 includes lead titanate zirconate (PZT) with a pseudo-cubic crystal indicating (100) orientation, the following can be considered.

The lead zirconate titanate included in the piezoelectric film 15 has a crystal structure of tetragonal crystals. The two lattice constants of the tetragonal crystals are a _t and c _t , a _t and c _t satisfy c _t > a _t , and the unit lattice is considered three mutually orthogonal length of the side of a _t, in the case of a rectangular parallelepiped, and a _t c _t's. Next, consider a case where the lattice constant a _t of the cubic crystal is approximately equal to the lattice constant a _{c of the} pseudo-cubic crystal, and the lattice constant c _{t of the} square crystal is approximately equal to the lattice constant a _c of the pseudo-cubic crystal. In such a case, the lead titanate zirconate is represented by (100) alignment in a quasi-cubic crystal, which means that the lead titanate zirconate is represented by (100) alignment (a-axis alignment) or (001) alignment (c-axis alignment) .

On the other hand, consider a case where the PZT included in the piezoelectric film 15 has a rhombohedral crystal structure and the lattice constant of the rhombohedral crystal is a _r . Next, consider a case where the lattice constant a _{r of the} rhombohedral crystal is approximately equal to the lattice constant a _c of the quasi-cubic crystal. In this case, PZT is expressed as (100) alignment in a quasi-cubic crystal, which means that PZT is expressed in (100) alignment in a rhombohedral crystal.

In this case, in this embodiment, according to the X-ray diffraction pattern of the piezoelectric film 15 using the θ-2θ method of CuKα line, the diffraction peak of the (400) plane represented by the pseudocubic crystal of lead titanate zirconate When the diffraction angle of is 2θ ₄₀₀ , 2θ ₄₀₀ satisfies the aforementioned expression (Equation 1), and becomes an expression that satisfies 2θ ₀₀₄ and is replaced by 2θ ₄₀₀ (2θ ₄₀₀ ≦ 96.5 °). Next, by this, the interval of the (400) plane represented by the pseudocubic crystal of lead titanate zirconate becomes longer. Therefore, the piezoelectric film 15 has a tetragonal crystal structure, and the content ratio of (001) aligned lead zirconate titanate can be compared to the piezoelectric film 15 having a tetragonal crystal structure and (100) aligned titanium The content of lead zirconate is even greater. That is, the polarization directions of the plurality of crystal grains included in the piezoelectric film 15 can be aligned, so that the piezoelectric characteristics of the piezoelectric film 15 can be improved.

In addition, in the present embodiment, when the relative dielectric constant of the piezoelectric film 15 is ε _r , ε _r satisfies the following formula (Expression 2).

ε _r ≦ 450‧‧‧ (Equation 2)

Accordingly, when the membrane structure 10 is used as a pressure sensor using a piezoelectric effect, for example, the detection sensitivity can be improved, and the detection circuit of the pressure sensor can be easily designed. Alternatively, when the membrane structure 10 is used, for example, as an ultrasonic vibrator using an inverse piezoelectric effect, an oscillation circuit can be easily designed.

For a film structure having a piezoelectric film containing lead zirconate titanate, the piezoelectric film is not good when the quality such as crystallinity of the piezoelectric film is not good due to, for example, low film density or low content of lead titanate zirconate. The piezoelectric characteristics will decrease. On the other hand, in a film structure having a piezoelectric film containing lead zirconate titanate, the crystallinity of the piezoelectric film is improved due to, for example, a high film density or a large lead zirconate titanate content. The piezoelectric characteristics of the piezoelectric film will be improved, and the relative dielectric constant of the piezoelectric film will not be small.

In this way, in a film structure having a piezoelectric film containing titanium lead zirconate, when the piezoelectric characteristics of the piezoelectric film are improved, the relative dielectric constant of the piezoelectric film may not be small. Next, if the relative permittivity of the piezoelectric film does not decrease, for example, when the piezoelectric film is used as a pressure sensor, the pressure sensor may be affected by the pressure sensor for reasons such as an increase in the capacity of the pressure sensor. The detection sensitivity of the sensor decreases, and the design of the detection circuit of the pressure sensor may become difficult.

In the film structure 10 of the present embodiment, 2θ ₀₀₄ satisfies the aforementioned expression (Expression 1), and ε _r satisfies the aforementioned expression (Expression 2). By satisfying the above formula (Equation 1) with 2θ ₀₀₄ , the piezoelectric film 15 can have a tetragonal crystal structure, and the content rate of (001) -aligned lead titanate zirconate becomes large, so it can be improved Piezoelectric characteristics. . In addition, since ε _r satisfies the aforementioned formula (Equation 2), the relative dielectric constant becomes smaller, so the detection sensitivity of the pressure sensor can be increased. That is, according to the film structure 10 of the present embodiment, the piezoelectric characteristics can be improved, and the detection sensitivity of the sensor using the piezoelectric effect can be improved. That is, in a film structure having a piezoelectric film containing titanium zirconate, the piezoelectric characteristics of the piezoelectric film can be improved, and the detection sensitivity of the pressure sensor using the piezoelectric film can be improved.

As described in the aforementioned Non-Patent Document 2, when PbTiO _{3 is} in a single crystal form and the crystallinity including alignment is improved, the relative dielectric constant becomes lower. That is, PZT, like PbTiO ₃ , improves the crystallinity including the alignment of the thin film, so that the relative dielectric constant becomes low. That is, the relative dielectric constant ε _{r of the} film structure 10 is as low as 450 or less, and it shows that the piezoelectric film 15 including the piezoelectric film of lead titanium zirconate becomes a single crystal.

It is appropriate that when the film structure 10 has the conductive film 18, when the relative dielectric constant of the piezoelectric film 15 measured by applying an alternating voltage having a frequency of 1 kHz between the conductive film 13 and the conductive film 18 is ε _r , the pressure The ε _{r of the} electrical film 15 satisfies the aforementioned formula (equation 2). By reducing the relative dielectric constant under an alternating voltage having such a frequency, for example, the clock frequency of the detection circuit can be increased, and the response speed of the pressure sensor using the membrane structure 10 can be increased.

When the film structure 10 has the conductive film 18, the ferroelectric capacitor CP1 is formed by the conductive film 13, the conductive film 15 and the conductive film 18. Next, ε _{r of the} piezoelectric film 15 is calculated from the electrostatic capacitance of the ferroelectric capacitor CP1 when an alternating voltage having a frequency of 1 kHz is applied between the conductive film 13 and the conductive film 18.

Relevance of those residual extremum points of the piezoelectric film 15 when P _r, P _r satisfy the following equation (Equation 3).

P _r ≧ 28μC / cm ² ‧‧‧ (Equation 3)

The residual sub-extremum is a value that becomes an index of the ferroelectric characteristics of a piezoelectric body that is also a ferroelectric substance. However, in general, a piezoelectric film having excellent ferroelectric characteristics also has excellent piezoelectric characteristics. That is, by the piezoelectric film P _r 15 satisfies the equation (Equation 3), the piezoelectric film can be improved ferroelectric properties 15, the piezoelectric characteristics of the piezoelectric film 15 can be improved.

And, P _r satisfies P _r ≧ 40μC / cm ² preferably satisfy P _r ≧ 50μC / cm ² more preferably satisfy P _r ≧ 55μC / cm ² and more preferably. The larger the P _r, can improve the characteristics of the piezoelectric ferroelectric film 15, the piezoelectric characteristics of the piezoelectric film 15 can be more improved.

When the film structure 10 has the conductive film 18, when the measurement shows a polarization voltage hysteresis curve (refer to FIG. 6 described later) of the polarization voltage of the piezoelectric film 15 when the voltage applied between the conductive film 13 and the conductive film 18 is changed , so that the conductive film 13 is applied to a voltage between the conductive film 18 is increased from 0 to a positive side of the extremum points returned to 0, the piezoelectric film 15 of the residual extremum points P _r. In addition, the voltage applied between the conductive film 13 and the conductive film 18 decreases from 0 toward the negative side and then returns to 0, which is the residual extreme value of the piezoelectric film 15- _Pr .

That is, when the measurement shows that the polarization field hysteresis curve of the polarization change of the piezoelectric film 15 when the electric field applied to the piezoelectric film 15 changes, the voltage applied to the piezoelectric film 15 increases from 0 to the positive side and then returns 0 points pole, the residual film 15 of the piezoelectric extremum points P _r. In addition, the electric field applied to the piezoelectric film 15 decreases from 0 toward the negative side and then returns to 0, which is the residual partial extreme value of the piezoelectric film 15- _Pr .

As shown in FIG. 2, when the film structure 10 includes the conductive film 18, the ferroelectric capacitor CP1 is formed by the conductive film 13, the conductive film 15 and the conductive film 18. Such a case, P _r 15 of the piezoelectric film, the residual substance ferroelectric capacitors CP1 of extremum points.

It is suitable that the piezoelectric film 15 includes the piezoelectric film 16 and the piezoelectric film 17. The piezoelectric film 16 contains a composite oxide composed of lead titanate zirconate formed on the film 14. The piezoelectric film 17 includes a composite oxide composed of lead titanate zirconate formed on the piezoelectric film 16. The piezoelectric film 16 has a compressive stress, and the piezoelectric film 17 has a tensile stress.

Consider a case where the piezoelectric film 16 has tensile stress and the piezoelectric film 17 has tensile stress. In such a case, when the upper surface 11a of the substrate 11 is the main surface, the film structure 10 tends to warp so as to have a downwardly convex shape. Therefore, for example, when the film structure 10 is processed using the photoetching technique, the shape accuracy is lowered, and the characteristics of the piezoelectric element formed by processing the film structure 10 are also lowered.

Also, consider a case where the piezoelectric film 16 has compressive stress and the piezoelectric film 17 has compressive stress. In such a case, when the upper surface 11a of the substrate 11 is the main surface, the film structure 10 is likely to be warped so as to have a shape protruding upward. Therefore, for example, when the film structure 10 is processed using the photoetching technique, the shape accuracy is lowered, and the characteristics of the piezoelectric element formed by processing the film structure 10 are also lowered.

On the other hand, in the present embodiment, the piezoelectric film 16 has a compressive stress, and the piezoelectric film 17 has a tensile stress. As a result, the amount of warpage of the film structure 10 can be reduced compared with the case where either of the piezoelectric film 16 and the piezoelectric film 17 has tensile stress, and the difference between the piezoelectric film 16 and the piezoelectric film 17 In any case where there is a compressive stress, the amount of warpage of the membrane structure 10 can be reduced. Therefore, for example, the shape accuracy when the film structure 10 is processed using the photoetching technique can be improved, and the characteristics of the piezoelectric element formed by processing the film structure 10 can be improved.

In addition, the piezoelectric film 16 has a compressive stress and the piezoelectric film 17 has a tensile stress. For example, when the piezoelectric film 17 and the piezoelectric film 16 are sequentially removed from the film structure 10, the piezoelectric film Before and after the removal of 17, the substrate 11 is deformed from the lower convex side to the upper convex side. Before and after the removal of the piezoelectric film 16, the substrate 11 is deformed from the upper convex side to the lower convex side, and it is confirmed.

It is appropriate that the piezoelectric film 16 contains a composite oxide composed of lead titanium zirconate (PZT) represented by the following general formula (Chemical Formula 6).

Pb (Zr _1-x Ti _x ) O ₃ ‧‧‧ (Chemical formula 6)

Here, x satisfies 0.32 ≦ x ≦ 0.52.

Among them, when x satisfies 0.32 ≦ x ≦ 0.48, the PZT included in the piezoelectric film 16 originally had a crystal structure composed of rhombohedral crystals, mainly due to the binding force from the substrate 11 and the like, having crystals of tetragonal crystal Structure, and easy (001) alignment. Next, the piezoelectric film 16 containing PZT is epitaxially grown on the film 14. In addition, when x satisfies 0.48 <x ≦ 0.52, the PZT included in the piezoelectric film 16 is originally composed of a tetragonal crystal structure, and has a tetragonal crystal structure, and is (001) aligned. Next, the piezoelectric film 16 containing PZT is epitaxially grown on the film 14. Accordingly, the direction of the polarization axis of the lead titanate zirconate included in the piezoelectric film 16 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric characteristics of the piezoelectric film 16 can be improved.

In addition, it is appropriate that the piezoelectric film 17 contains a composite oxide composed of lead zirconate titanate (PZT) represented by the following general formula (chemical formula 7).

Pb (Zr _1-y Ti _y ) O ₃ ‧‧‧ (Chemical formula 7)

Here, y satisfies 0.32 ≦ y ≦ 0.52.

However, when y satisfies 0.32 ≦ y ≦ 0.48, the PZT included in the piezoelectric film 17 originally has a crystal structure of rhombohedral crystals, mainly due to the binding force from the substrate 11 and the like, and has crystals of tetragonal crystals Structure, and easy (001) alignment. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16. In addition, when y satisfies 0.48 <y ≦ 0.52, the PZT included in the piezoelectric film 17 is originally composed of a tetragonal crystal structure, and has a tetragonal crystal structure, and is (001) aligned. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16. Thereby, the direction of the polarization axis of the lead titanate zirconate included in the piezoelectric film 17 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric characteristics of the piezoelectric film 17 can be improved.

As explained using FIG. 14 described later, the piezoelectric film 16 having compressive stress can be formed by, for example, a sputtering method. In addition, when explaining the manufacturing process of the film structure, the piezoelectric film 17 having tensile stress may be formed by a coating method such as a sol-gel method, as explained using FIG. 1 described later.

FIG. 5 is a diagram schematically showing a cross-sectional structure of two piezoelectric films included in the film structure of the embodiment. FIG. 5 is a scanning electron microscope (Scanning Electron Microscope: SEM) observation of the cross section formed by cleaving the substrate 11 included in the film structure 10 of the embodiment shown in FIG. In the video, the piezoelectric film 16 and the piezoelectric film 17 are displayed in a pattern.

FIG. 6 is a diagram schematically showing the electric field dependence of the polarization of the piezoelectric film included in the film structure of the embodiment. 6 is a schematic diagram showing the polarization of the piezoelectric film 15 when an electric field is included between the lower electrode (conductive film 13) and the upper electrode (conductive film 18) of the film structure 10 of the embodiment shown in FIG. Graph of the hysteresis curve of the polarized electric field of change.

As shown in FIG. 5, when the piezoelectric film 16 is formed by a sputtering method, the piezoelectric film 16 includes a plurality of crystal grains 16g integrally formed from the lower surface to the upper surface of the piezoelectric film 16. In addition, between two adjacent crystal grains 16g in the main surface of the substrate 11 (upper surface 11a in FIG. 1), it is not easy to leave voids or voids. Therefore, when the piezoelectric film 16 is processed by a focused ion beam (Focused Ion Beam: FIB) method to form a cross section for SEM observation, the cross section is easily regarded as a single cross section, and the crystal grain 16g is difficult to be observed.

On the other hand, when the piezoelectric film 17 is formed by a coating method, the piezoelectric film 17 includes a plurality of layers of films 17f that are stacked on each other in the thickness direction of the piezoelectric film 17. The film 17f as each plural layer includes plural crystal grains 17g integrally formed from the lower surface to the upper surface of the film 17f of one layer. In addition, between two layers of films 17f adjacent to each other in the thickness direction of the piezoelectric film 17, voids or voids remain.

As shown in Fig. 5, the suitable ones are the spontaneous polarization of each of the plural crystal grains. This spontaneous polarization includes a polarization component P1 parallel to the thickness direction of the piezoelectric film 16 and a polarization component P1 included in each spontaneous polarization of the plurality of crystal grains, and faces each other in the same direction.

In this case, as shown in FIG. 6, in the initial state, the piezoelectric film 15 has a large spontaneous polarization. Therefore, when the electric field increases from the starting point SP of 0 to the positive side and returns to 0 again, and then decreases to the negative side and returns to the end point EP of 0 again, the electric field dependence of the polarizing of the piezoelectric film 15 is shown. The hysteresis curve shows the curve starting from the point leaving the origin as the starting point SP. That is, when the film structure 10 of the present embodiment is used as a piezoelectric element, it is not necessary to perform polarization treatment on the piezoelectric film 15 before use.

This should be such that the piezoelectric film 15 has a large spontaneous polarization in the initial state. For example, when the piezoelectric film 16 is formed using the film forming device as an RF sputtering device described later in FIGS. 8 to 10, the electric The slurry or electrons are not easily affected by the ground potential (zero potential). By stably sealing between the target and the substrate, a large amount of charge can be accumulated on the substrate.

7 is a diagram illustrating the state of film epitaxial growth of each layer included in the film structure of the embodiment. In addition, the layers of the substrate 11, the alignment film 12, the conductive film 13, the film 14, and the piezoelectric film 15 are schematically shown in FIG.

The lattice constant of silicon included in the substrate 11, the lattice constant of ZrO ₂ included in the alignment film 12, the lattice constant of Pt included in the conductive film 13, the lattice constant of SRO included in the film 14, and The lattice constant of PZT of the piezoelectric film 15 is shown in Table 1.

As shown in Table 1, the lattice constant of Si is 0.543 nm, the lattice constant of ZrO ₂ is 0.511 nm, and the unification of the lattice constant of ZrO ₂ relative to the lattice constant of Si is 6.1%, which is relatively small, so The integration of the lattice constant of ZrO ₂ with respect to the lattice constant of Si is good. Therefore, as shown in FIG. 7, the alignment film 12 containing ZrO ₂ can be epitaxially grown on the upper surface 11 a which is the main surface of the (100) surface of the substrate 11 containing silicon single crystal. That is, the alignment film 12 containing ZrO ₂ can be structured to be (100) aligned with a cubic crystal on the (100) surface of the substrate 11 containing silicon single crystal, and the crystallinity of the alignment film 12 can be improved.

The alignment film 12 has a cubic crystal structure and includes a (100) aligned zirconia film 12a. In this case, the zirconia film 12a is oriented along the <100> direction of the upper surface 11a as the main surface of the substrate 11 made of a silicon substrate of the zirconia film 12a, and the <100> direction of the upper surface 11a of the substrate 11 itself Align in parallel.

The zirconium oxide film 12a is parallel to the <100> direction of the upper surface 11a of the substrate 11 and parallel to the <100> direction of the upper surface 11a of the substrate 11 composed of a silicon substrate, which includes not only the <100> of the zirconium oxide film 12a When the> direction is completely parallel to the <100> direction along the top surface 11a of the substrate 11 itself, the angle between the <100> direction of the zirconia film 12a and the <100> direction along the top surface 11a of the substrate 11 itself is 20 ° below the occasion. In addition, not only the zirconia film 12a but also the in-plane alignment of the films of other layers are the same.

On the other hand, as shown in Table 1, it may be that the lattice constant of ZrO ₂ is 0.511 nm, the lattice constant of Pt is 0.392 nm, and Pt rotates 45 ° in the plane, the diagonal length becomes 0.554 nm, The unconformity of the diagonal length with respect to the lattice constant of ZrO ₂ is relatively small at 8.1%, and the conductive film 13 containing Pt can be made on the (100) surface of the alignment film 12 containing ZrO ₂ Epitaxy grows. For example, in the aforementioned Patent Document 2 and the aforementioned Non-Patent Document 1, it is reported that an in-plane LSCO film composed of an LSCO having a lattice constant (0.381 nm) having the same degree as that of Pt is not a Pt film. The 100> direction is aligned parallel to the <110> direction in the main surface of the silicon substrate.

However, the inventors of the present invention first discovered that the lattice constant of Pt and the lattice constant of ZrO ₂ are not integrated by up to 26%, but Pt is not rotated 45 ° in the plane, so that the conductive film 13 containing Pt can be made on silicon The epitaxial growth on the substrate. That is, the conductive film 13 has a cubic crystal structure and includes a (100) aligned platinum film 13a. In this case, the platinum film 13a is aligned so that the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the platinum film 13a becomes parallel to the <100> direction of the upper surface 11a of the substrate 11 itself . It can be seen that by doing this, the conductive film 13 containing Pt can be (100) aligned with a cubic crystal structure on the (100) surface of the alignment film 12 containing ZrO ₂ , and the crystallinity of the conductive film 13 can be improved.

Also, by adjusting the conditions when forming ZrO ₂ or the conditions when forming Pt, it is possible to rotate the Pt in the plane by 45 °, that is, within the main surface of the substrate 11, the <100> direction of Pt is along In the state of Si in the <110> direction, the conductive film 13 containing Pt is epitaxially grown on the (100) surface of the alignment film 12 containing ZrO ₂ .

In addition, as shown in Table 1, the lattice constant of Pt is 0.392 nm, the lattice constant of SRO is 0.390 to 0.393 nm, and the lattice constant mismatch of PZT with respect to the lattice constant of Pt is 0.5% or less. It is small, so the integration of the lattice constant of SRO with respect to the lattice constant of Pt is good. Therefore, as shown in FIG. 7, the film 14 containing SRO can be epitaxially grown on the (100) surface of the conductive film 13 containing Pt. In other words, the film 14 containing SRO can be structured with (100) orientation on the (100) surface of the conductive film 13 containing Pt, and the crystallinity of the film 14 can be improved.

The film 14 has a quasi-cubic crystal structure and is an SRO film 14a including (100) alignment. In this case, the SRO film 14a is aligned so that the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the SRO film 14a becomes parallel to the <100> direction of the upper surface 11a of the substrate 11 itself .

In addition, as shown in Table 1, the lattice constant of SRO is 0.390 to 0.393 nm, the lattice constant of PZT is 0.411 nm, and the lattice constant of PZT relative to the lattice constant of SRO is 4.5 to 5.2%. Since it is small, the integration of the lattice constant of PZT with respect to the lattice constant of SRO is good. Therefore, as shown in FIG. 7, the piezoelectric film 15 containing PZT can be epitaxially grown on the (100) surface of the film 14 containing SRO. In other words, the piezoelectric film 15 containing PZT can be structured with (001) orientation in a square crystal or a quasi-cubic crystal structure in a (100) orientation on the (100) surface of the film 14 containing SRO. The crystallinity of the piezoelectric film 15 is improved.

The piezoelectric film 15 has a tetragonal crystal structure, and is a lead titanate-zirconate film 15a with (001) orientation. In this case, the lead titanate zirconate film 15a is oriented along the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the lead titanate zirconate film 15a and the <100> direction of the upper surface 11a of the substrate 11 itself Align in parallel.

In this way, the inventors of the present invention first discovered that the lead titanate zirconate can be epitaxially grown on the silicon substrate without rotating the lead titanate zirconate by 45 ° in the plane. This is completely different from the relationship of the in-plane alignment described in the aforementioned Patent Document 2 and the aforementioned Non-Patent Document 1, for example.

In addition, a film containing lead titanate zirconate may be formed between the film 14 and the piezoelectric film 15. The film is represented by the following general formula (Chemical Formula 8), and may include a composite oxide represented by (100) alignment in a quasi-cubic crystal.

Pb (Zr _1-v Ti _v ) O ₃ ‧‧‧ (Chemical Formula 8)

Here, v satisfies 0 ≦ v ≦ 0.1.

Thereby, the piezoelectric film 15 containing PZT can be more easily displayed on the (100) surface of the film 14 containing SRO, and the crystal structure of (001) orientation or quasi-cubic crystal can be displayed as (100) With the alignment, the crystallinity of the piezoelectric film 15 can be more easily improved.

    <Film-forming device>    

Next, the piezoelectric film 15 included in the film structure that can improve the piezoelectric characteristics of the piezoelectric film and can increase the detection sensitivity of the pressure sensor using the piezoelectric film for forming Piezo film 16 film forming device. This film forming apparatus is a sputtering apparatus that forms a film containing lead titanate zirconate on the surface of a substrate by sputtering the surface of a target containing lead titanate zirconate in a vacuum chamber.

In the following, a so-called surface suitable for forming a film on the lower surface of the substrate by sputtering on the upper surface of the target arranged opposite to the lower surface of the substrate by sputtering in the vacuum chamber will be described below An example of a face down type sputtering device. However, the film forming apparatus for forming the piezoelectric film 16 is a so-called face-up type in which a film is formed on the upper surface of the substrate by sputtering in the vacuum chamber under the target disposed opposite to the upper surface of the substrate Sputtering equipment can also be applied.

8 and 9 are schematic cross-sectional views showing a film-forming apparatus according to an embodiment. 9 is an enlarged view showing the vicinity of the substrate holding portion 25 and the support portion 26 in the cross-sectional view of FIG. 8. Fig. 10 is a plan view schematically showing the substrate holding portion of the film forming apparatus of the embodiment.

As shown in FIG. 8, the film forming apparatus 20 includes a vacuum chamber 21, a vacuum exhaust part 22, gas supply parts 23 and 24, a substrate holding part 25, a supporting part 26, a rotation driving part 27, a substrate heating part 28, and adhesion prevention The board 29, the target holding portion 31, and the power supply portion 32. The substrate holding portion 25 holds the substrate SB. As the substrate SB, for example, a film structure in which the alignment film 12, the conductive film 13, and the film 14 are formed on the substrate 11 can be used.

The vacuum chamber 21 is provided to be vacuum exhaustable. The vacuum exhaust unit 22 evacuates the vacuum chamber 21 in vacuum. The gas supply unit 23 supplies a rare gas such as argon (Ar) gas into the vacuum chamber 21. The gas supply unit 24 supplies a raw material gas such as oxygen (O ₂ ) gas or nitrogen (N ₂ ) gas into the vacuum chamber 21.

The vacuum chamber 21 includes, for example, a bottom plate portion 21a, a side plate portion 21b, and a top plate portion 21c. The side plate portion 21b is formed with an opening OP1, and the opening OP1 is connected with a vacuum exhaust portion 22 that evacuates the vacuum chamber 21 in vacuum. As the vacuum exhaust unit 22, for example, a cryo pump can be used.

In the example shown in FIG. 8, the top plate portion 21c is provided with an opening OP2, and the vacuum chamber 21 includes a lid portion 21d that hermetically closes the opening OP2. The lid portion 21d includes, for example, a side plate portion 21e and a top plate portion 21f. The space formed in the vacuum chamber 21 communicates with the space surrounded by the side plate portion 21e and the top plate portion 21f. The top plate portion 21f is provided with an opening OP3. Although not shown in the drawings, a transport port for transporting the substrate SB into the vacuum chamber 21 is formed in the side plate portion 21b.

The gas supply unit 23 is connected to the gas supply pipe 23b via the flow controller 23a, and the rare gas supplied from the gas supply unit 23 is adjusted in flow rate by the flow controller 23a, and is supplied into the vacuum chamber 21 from the gas supply pipe 23b. In addition, the gas supply unit 24 is connected to the gas supply pipe 24b via the flow controller 24a, and the raw material gas supplied from the gas supply unit 24 is adjusted in flow rate by the flow controller 24a and supplied into the vacuum chamber 21 from the gas supply pipe 24b. . In the example shown in FIG. 8, the gas supply pipe 23 b and the gas supply pipe 24 b are the same. However, the gas supply pipe 23 b and the gas supply pipe 24 b may be provided separately.

The substrate holding portion 25 holds the substrate SB in the vacuum chamber 21. As shown in FIGS. 8 to 10, the substrate holding portion 25 is in contact with the substrate holding portion 25 at the outer peripheral portion of the substrate SB, and holds the substrate SB in a state where the central portion of the substrate SB is separated from the substrate holding portion 25.

It is considered that, for example, the substrate holding portion 25 overlaps the bottom surface of the substrate SB in a plan view, and the substrate holding portion 25 contacts the bottom surface of the substrate SB, for example. In such a case, the central portion of the substrate SB is not easily thermally insulated from the substrate holding portion 25 and is easily affected by heat from the substrate holding portion 25. In addition, the central portion of the substrate SB is easily affected by the heat capacity of the substrate holding portion 25, so it is difficult to control the temperature of the central portion of the substrate SB. Therefore, when the substrate heating portion 28 heats the substrate SB, the actual temperature of the central portion of the substrate SB deviates from the target temperature, and the quality of the crystallinity of the film formed on the surface of the substrate SB varies.

On the other hand, in the present embodiment, the outer peripheral portion of the substrate SB is in contact with the substrate holding portion 25, but the central portion of the substrate SB is separated from the substrate holding portion 25. In such a case, the central portion of the substrate SB is easily thermally insulated from the substrate holding portion 25 and is not easily affected by heat from the substrate holding portion 25. In addition, the central portion of the substrate SB is not easily affected by the heat capacity of the substrate holding portion 25, so it is easy to control the temperature of the central portion of the substrate SB. Therefore, when the substrate SB is heated by the substrate heating portion 28, the actual temperature of the central portion of the substrate SB can be prevented or suppressed from shifting away from the target temperature, and the crystallinity of the film formed on the surface of the substrate SB can be prevented or suppressed The quality is discrete.

As described above, the film forming apparatus 20 of the present embodiment forms a film on the lower surface of the substrate SB by sputtering on the upper surface of the target TG disposed opposite to the lower surface of the substrate SB in the vacuum chamber 21 A face down type sputtering device. In such a case, for example, the substrate holding portion 25 does not overlap with the lower surface of the substrate SB in a plan view, but a film can be formed in the central portion of the lower surface of the substrate SB.

The shape of the substrate holding portion 25 is not particularly limited. The substrate holding portion 25 preferably includes an insulating member 25a which is composed of an insulating member and surrounds the substrate SB in a plan view, and is composed of an insulating member, and It is preferable that a plurality of protruding portions 25b protruding from the insulating enclosing portion 25a toward the center side of the substrate SB in a planar view. That is, it is preferable that the substrate holding portion 25 has a so-called Wude shape (see FIG. 10 (A)). In addition, the substrate holding portion 25 preferably holds the substrate SB in a state where the outer peripheral portion (outer edge portion) of the lower surface of the substrate SB is in contact with the upper surface of each of the plurality of protruding portions 25b. The plurality of protrusions 25b are arranged so that the center of gravity of the substrate SB held by the plurality of protrusions 25b is arranged in a polygonal shape formed by the plurality of protrusions 25b connected in sequence in plan view in a plan view. good.

The smaller the area where one protruding portion 25b contacts the substrate SB, the more the thermal and electrical influences on the substrate SB during film formation can be reduced, and the contact area is preferably 20 mm ² or less. In short, by reducing the contact area between the substrate SB and the protruding portion 25b as much as possible, thermal insulation and electrical insulation can be obtained at the same time, plasma electrons can charge the substrate, and the heat accumulated in the substrate can not escape.

The protruding portion 25b has the shape shown in FIGS. 10 (B) to (D). FIG. 10 (B) is a front view of the protrusion 25b, FIG. 10 (C) is a top view of the protrusion 25b, and FIG. 10 (D) is a side view of the protrusion 25b. The corner 25b1 of the protrusion 25b is not sharp and has a curved surface. If the corner is sharp, the film formed on the corner is likely to peel off. If the corner has a curved surface, the film formed on the corner will not be easily peeled off, and fine particles can be reduced.

In addition, the protruding portion 25b may be referred to as an insulating substrate holding portion, and the insulating surrounding portion 25a and the protruding portion 25b may be collectively referred to as an insulating substrate holding portion. The insulating surrounding portion 25a may also be referred to as a third insulating member.

In such a case, no part of the substrate holding portion 25 is disposed under the central portion of the substrate SB, so the central portion of the substrate SB is more likely to be thermally insulated from the substrate holding portion 25 and less likely to be affected by the substrate holding portion 25 heat effects. In addition, the central portion of the substrate SB is less likely to be affected by the heat capacity of the substrate holding portion 25, so it is easier to control the temperature of the central portion of the substrate SB. Therefore, when the substrate heating portion 28 heats the substrate SB, the actual temperature of the central portion of the substrate SB can be prevented or suppressed from shifting away from the target temperature, and the film formed on the surface of the substrate SB can be further prevented or suppressed The crystallinity and other qualities are discrete.

The insulating member of the insulating surrounding portion 25a and each insulating member of the plurality of protruding portions 25b are not particularly limited, but for example, quartz such as fused quartz or synthetic quartz, or aluminum (alumina) is preferably used. However, when the substrate SB is composed of a silicon substrate, from the viewpoint of not contacting the substrate SB and contaminating the substrate SB, each insulating member of the plurality of protrusions 25b is preferably composed of quartz.

In addition, the substrate holding portion 25 is further composed of a conductive member, and may include the conductive surrounding portion 25c surrounding the insulating surrounding portion 25a. A stepped portion 25d is formed in the inner edge portion of the conductive surrounding portion 25c, and the substrate holding portion 25 may be formed by the outer edge portion of the insulating surrounding portion 25a being held in the stepped portion 25d.

As the substrate SB held by the substrate holding portion 25, a substrate SB composed of a wafer having a circular shape in plan view can be used. At this time, the substrate holding portion 25 rotatably holds the substrate SB with the rotation axis RA1 passing through the center CN1 (see FIG. 10) of the surface of the substrate SB.

In addition, the direction in which the rotation axis RA1 extends may be a direction parallel to the vertical direction. At this time, the surface of the substrate SB held by the substrate holding portion 25 is parallel to the horizontal plane.

The support portion 26 is attached to the vacuum chamber 21 and supports the substrate holding portion 25 in the vacuum chamber 21. The support portion 26 includes a conductive member (the conductive members 41 and 42 described later) which is attached to the vacuum chamber 21 and supports the substrate holding portion 25 in the vacuum chamber 21. The support portion 26 is provided to be rotatable integrally with the substrate holding portion 25 with the rotation axis RA1 perpendicular to the surface of the substrate SB as the center. The rotation drive section 27 rotates the support section 26.

In the examples shown in FIGS. 8 and 9, the supporting portion 26 includes, as the conductive member, the conductive member 41 attached to the vacuum chamber 21 and the conductive member 42 attached to the conductive member 41. The conductive members 41 and 42 are rotatably provided integrally with the substrate holding portion 25 around the rotation axis RA1. The rotation drive unit 27 rotatably drives the conductive members 41 and 42.

In addition, the conductive member 42 may also be referred to as a conductive support portion, and the conductive member 42 and the conductive surrounding portion 25c may be collectively referred to as a conductive support portion. In addition, the conductive surrounding member 25c may also be referred to as a first conductive member. In addition, the conductive member 42 may also be referred to as a second conductive member.

The conductive member 41 includes a base portion 41a having a cylindrical shape, a cylindrical shape, a shaft portion 41b having a diameter smaller than the diameter of the base portion 41a, and is provided rotatably with the base portion 41a. In addition, the conductive member 41 has a ring shape, and includes a connecting portion 41c that connects the base portion 41a and the shaft portion 41b. The base portion 41a, the shaft portion 41b, and the connecting portion 41c are integrally formed, and the base portion 41a, the shaft portion 41b, and the connecting portion 41c are made of metal such as stainless steel, for example.

The conductive member 41 is provided such that the shaft portion 41b protrudes upward from the opening OP3 of the lid portion 21d, and the shaft portion 41b protruding upward from the opening OP3 is sealed, for example, by a seal portion CE1 composed of a magnetic fluid seal地 Mounted to the opening OP3. In addition, the shaft portion 41b is rotatably provided around the rotation axis RA1 perpendicular to the surface of the substrate SB through the sealing portion CE1. Therefore, the shaft portion 41b is attached to the vacuum chamber 21 which is the lid portion 21d. At this time, the shaft portion 41b is electrically connected to the vacuum chamber 21. As described above, the vacuum chamber 21 is made of metal such as stainless steel, and is grounded. Therefore, the conductive member 41 is also grounded.

The rotation drive unit 27 includes, for example, a motor 27a, a belt 27b, and a pulley 27c. The shaft portion 41b is connected to the rotating shaft 27d of the motor 27a through the pulley 27c and the belt 27b. The rotation driving force of the motor 27a is transmitted to the shaft portion 41b through the belt 27b and the pulley 27c, and the rotation driving portion 27 rotatably drives the conductive member 41 around the rotation axis RA1.

The conductive member 42 includes a base portion 42a having a cylindrical shape, a cylindrical shape, a shaft portion 42b having a diameter smaller than the diameter of the base portion 42a, and is provided rotatably with the base portion 42a. In addition, the conductive member 42 has a ring shape, and includes a connecting portion 42c that connects the base portion 42a and the shaft portion 42b. The base portion 42a, the shaft portion 42b and the connecting portion 42c are integrally formed, and the base portion 42a, the shaft portion 42b and the connecting portion 42c are made of metal such as stainless steel, for example.

The base 42a is concentric with the base 41a so that the outer peripheral surface of the base 42a faces the inner periphery of the base 41a. The shaft portion 42b is concentric with the shaft portion 41b so that the outer circumferential surface of the shaft portion 42b faces the inner circumferential surface of the shaft portion 41b. The connection portion 42c is fixed to the connection portion 41c by the insulating member 51, whereby the conductive member 42 is made to rotate integrally with the conductive member 41. As the insulating member 51, for example, an insulating member made of alumina can be used.

The base portion 42a is fixed to the substrate holding portion 25 using, for example, a screw 43 made of a conductive structure. Therefore, when the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the potential of the conductive surrounding portion 25c, namely the substrate holding portion 25, is equal to the potential of the base 42a, that is, the conductive member 42. Alternatively, when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when there is no conductivity, the potential of the portion of the substrate holding portion 25 that contacts the screw 43 is equal to that of the base portion 42a, that is, the conductive member 42 Potential.

In addition, as described above, the conductive member 42 is fixed to the substrate holding portion 25 by using, for example, a screw 43 made of a conductive member, and the conductive member 41 attached to the vacuum chamber 21 becomes an insulating member 51 interposed therebetween , The conductive member 42 and the screw 43 support the substrate holding portion 25. At this time, the insulating member 51 is interposed between the conductive member 41 and the substrate holding portion 25.

In addition, the conductive member 42 serves to support the substrate holding portion 25 through the screw 43. At this time, the insulating member 53 is interposed between the vacuum chamber 21 and the conductive member 42, and the conductive member 42 is in an electrically floating state with respect to the vacuum chamber 21.

In addition, an insulating member 52 is provided around the screw 43 made of a conductive member. As the insulating member 52, for example, an insulating member made of alumina can be used. At this time, the insulating member 52 is disposed between the conductive member 41 and the substrate holding portion 25, so it can also be said that the insulating member 52 is interposed between the conductive member 41 and the substrate holding portion 25.

It is considered that the insulating member 51 is not interposed between the conductive member 41 and the substrate holding portion 25, and the conductive member 41 and the substrate holding portion 25 are in electrical contact. In such a case, and the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is grounded, and the conductive surrounding portion 25c, also That is, the potential of the substrate holding portion 25 becomes zero potential. Therefore, when plasma is generated in the vacuum chamber 21 to sputter the target TG, the plasma or electrons are easily affected by the ground potential (zero potential), and it is not easy to stably seal between the target TG and the substrate SB. That is, when a piezoelectric film such as lead titanate zirconate is formed, the charge distribution of the piezoelectric film during film formation is difficult to be constant, and the quality of the film such as crystallinity is not easily improved.

In addition, when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when there is no conductivity, plasma or electrons are still easily affected by the ground potential (zero potential), and it is still not easy to securely enclose the target Between TG and substrate SB.

On the other hand, in the present embodiment, the insulating member 52 is interposed between the conductive member 41 and the substrate holding portion 25. In such a case, and the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is in an electrically floating state. Therefore, when plasma is generated in the vacuum chamber 21 and the target TG is sputtered, the plasma or electrons are less likely to be affected by the ground potential (zero potential), and are easily and securely enclosed between the target TG and the substrate SB. That is, when a piezoelectric film such as lead titanate zirconate is formed, the charge distribution of the piezoelectric film during film formation tends to be constant, and the quality of the film such as crystallinity is easily improved.

In addition, the insulating member 53 may also be referred to as a first insulating member, the insulating member 52 may also be referred to as a first insulating member, and the insulating member 53 and the insulating member 52 may be collectively referred to as a first insulating member.

In addition, even when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when there is no conductivity, compared with the case where the insulating member 52 is not interposed between the conductive member 41 and the substrate holding portion 25, Plasma or electrons are not easily affected by the ground potential (zero potential), and are easily sealed between the target TG and the substrate SB.

In addition, when a certain member has conductivity, it means that the resistivity of the member is, for example, 10 ^-6 Ωm or less. On the other hand, when a certain member has insulation, it means that the resistivity of the member is, for example, 10 ⁸ Ωm or more.

As described above, between the vacuum chamber 21 and the conductive member 42, the insulating members 52 and 53 are interposed, and the conductive member 42 is in an electrically floating state.

It is considered that the insulating member 53 is not interposed between the vacuum chamber 21 and the conductive member 42 and the vacuum chamber 21 and the conductive member 42 are in electrical contact. In such a case, and the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is grounded, and the conductive surrounding portion 25c, also That is, the potential of the substrate holding portion 25 becomes zero potential. Therefore, when plasma is generated in the vacuum chamber 21 and the target is sputtered, the plasma or electrons are easily affected by the ground potential (zero potential), and are not easily sealed between the target TG and the substrate SB.

In addition, when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when there is no conductivity, plasma or electrons are still easily affected by the zero potential, and it is still not easy to securely seal the target TG and the substrate SB between.

On the other hand, in the present embodiment, the insulating member 53 is interposed between the vacuum chamber 21 and the conductive member 42, and the conductive member 42 is in an electrically floating state. In such a case, and the substrate holding portion 25 has the conductive surrounding portion 25c, that is, when it has conductivity, the conductive surrounding portion 25c, that is, the substrate holding portion 25 is in an electrically floating state. Therefore, when plasma is generated in the vacuum chamber 21 and the target TG is sputtered, the plasma or electrons are less likely to be affected by the ground potential (zero potential), and are easily and securely enclosed between the target TG and the substrate SB. That is, when a piezoelectric film such as lead titanate zirconate is formed, the charge distribution of the piezoelectric film during film formation is likely to be constant, and the quality of the film such as crystallinity is easily improved.

In addition, even when the substrate holding portion 25 does not have the conductive surrounding portion 25c, that is, when there is no conductivity, compared with the case where the insulating member 53 is not interposed between the vacuum chamber 21 and the conductive member 42, the plasma Or electrons, are not easily affected by the ground potential (zero potential), and are easily sealed between the target TG and the substrate SB.

Furthermore, the insulating member 53 may be disposed between, for example, the upper end portion of the shaft portion 41b and the shaft portion 42b, between the lower end portion of the shaft portion 41b and the lower end portion of the shaft portion 42b, and the lower surface of the connecting portion 41c Between the upper surface of the portion 42c. As the insulating member 53, for example, an insulating member made of PEEK (Poly Ether Ether Keton, polyether ether ketone) resin or alumina can be used.

In addition, a slip ring 44 surrounding the shaft portion 42b of the conductive member 42 may be provided. The inner peripheral surface of the slip ring 44 contacts the outer peripheral surface of the shaft portion 42b. In such a case, since the potential of the shaft portion 42b can be freely controlled via the slip ring 44, the potential of the conductive member 42 can be controlled to be equal to a constant potential.

As shown in FIGS. 8 and 9, the support portion 26 may include a conductive member 45 that supports the substrate holding portion 25. The conductive member 45 includes a base portion 45a having a cylindrical shape, a cylindrical shape, a shaft portion 45b having a diameter smaller than that of the base portion 45a, and a shaft portion 45b having a diameter smaller than that of the base portion 45a. In addition, the conductive member 45 has a ring shape, and includes a connecting portion 45c connecting the base portion 45a and the shaft portion 45b. The base portion 45a, the shaft portion 45b and the connecting portion 45c are integrally formed, and the base portion 45a, the shaft portion 45b and the connecting portion 45c are made of metal such as stainless steel, for example.

In the examples shown in FIGS. 8 and 9, the base 45a is concentric with the base 42a and the base 41a so that the outer circumferential surface of the base 45a faces the inner circumference of the base 42a. The shaft portion 45b is concentric with the shaft portion 42b and the shaft portion 41b so that the outer circumferential surface of the shaft portion 45b faces the inner circumferential surface of the shaft portion 42b. The connecting portion 45c is fixed to the connecting portion 42c and the connecting portion 41c by the insulating member 54, whereby the conductive member 45 is configured to rotate integrally with the conductive member 42 and the conductive member 41.

In addition, as described above, the conductive member 42 is fixed to the substrate holding portion 25 by using, for example, a screw 43 made of a conductive member, and the conductive member 45 becomes an insulating member 51, a conductive member 42 and a screw interposed therebetween 43, Support substrate holding portion 25. At this time, the insulating member 52 is interposed between the conductive member 45 and the substrate holding portion 25.

In addition, as described above, an insulating member 52 is provided around the screw 43 made of a conductive member. At this time, the insulating member 52 is disposed between the conductive member 45 and the substrate holding portion 25, so it can also be said that the insulating member 52 is interposed between the conductive member 45 and the substrate holding portion 25.

Furthermore, between the upper end of the shaft 42b and the shaft 45b, between the lower end of the shaft 42b and the lower end of the shaft 45b, and between the lower surface of the connecting portion 42c and the upper surface of the connecting portion 45c, Mediated the insulating member 54. As the insulating member 54, for example, an insulating member made of PEEK resin or alumina can be used.

The substrate heating unit 28 heats the substrate SB. The substrate heating portion 28 is arranged to face the upper surface of the substrate SB held by the substrate holding portion 25, and is rotatably provided integrally with the support portion 26. As the substrate heating unit 28, a lamp unit including, for example, an infrared lamp can be used.

The adhesion prevention plate 29 is composed of a conductive member installed in the vacuum chamber 21. The anti-adhesion plate 29 is a film forming apparatus 20 that prevents the film forming material from adhering to the vacuum chamber 21 when the film is formed by attaching the surface of the target TG and the film forming material to the surface of the substrate SB by sputtering Those who do not want to attach the film-forming material. In the present embodiment, the anti-adhesion plate 29 prevents the film-forming material from adhering to the portion arranged around the substrate SB held by the substrate holding portion 25 in plan view. In the example shown in FIG. 8, the adhesion preventing plate 29 prevents the film forming material from adhering to the substrate holding portion 25. As the conductive member constituting the adhesion prevention plate 29, a conductive member composed of stainless steel can be used. With this, the temperature of the anti-adhesion plate 29 can be easily adjusted by, for example, the cooling pipe 29a through which cooling water is passed, and the influence of the anti-adhesion plate 29 on the temperature of the substrate SB held by the substrate holding portion 25 can be reduced.

In addition, the anti-adhesion plate 29 is arranged at a distance within 30 mm (preferably within 25 mm, more preferably within 20 mm) from the substrate SB.

In addition, the reason why the adhesion prevention plate 29 is preferably water-cooled is as follows. If the anti-adhesion plate is not water-cooled, the hardness of the film adhering to the anti-adhesion plate will increase and it is easy to peel off. On the other hand, if the water-cooling anti-adhesion plate 29 is used, the thermal energy of the film on the surface of the anti-adhesion plate 29 will decrease , The film stress also becomes smaller, so the attached film becomes difficult to peel. As a result, the maintenance cycle of the film forming apparatus can be extended.

In addition, the anti-adhesion plate 29 may also be referred to as a conductive anti-adhesion plate.

In addition, between the vacuum chamber 21 and the adhesion prevention plate 29, an insulating member 55 is interposed, and the adhesion prevention plate 29 is in an electrically floating state. In addition, between the vacuum chamber 21 and the insulating member 55, the conductive member 46 is interposed, and between the insulating member 55 and the adhesion prevention plate 29, the conductive member 47, the conductive member 46, and the conductive member 47 are interposed In the state where the insulating member 55 is interposed, the screws 56 made of the insulating member may be used to make the connection.

Consider a case where the insulating member 55 is not interposed between the vacuum chamber 21 and the adhesion prevention plate 29, and the vacuum chamber 21 and the adhesion prevention plate 29 are in electrical contact. In this case, the anti-adhesion plate 29 becomes grounded, and the potential of the anti-adhesion plate 29 becomes zero potential. Therefore, when plasma is generated in the vacuum chamber 21 to sputter the target TG, the plasma or electrons are easily affected by the ground potential (zero potential), and it is not easy to stably seal between the target TG and the substrate SB. That is, when a piezoelectric film such as lead titanate zirconate is formed, the charge distribution of the piezoelectric film during film formation is difficult to be constant, and the quality of the film such as crystallinity is not easily improved.

In addition, when the anti-adhesion plate 29 disposed within a distance of 30 mm from the substrate SB is grounded, and the piezoelectric film is formed on the substrate SB, the piezoelectric film located at the end of the substrate SB becomes cloudy. If the anti-adhesion plate 29 is farther than 30 mm, even if the anti-adhesion plate is at ground potential, the piezoelectric film will not be cloudy, but the anti-adhesion plate at such a distant position cannot fully function as an anti-adhesion plate.

In addition, the insulating member 55 may also be referred to as a second insulating member.

On the other hand, in the present embodiment, the insulating member 55 is interposed between the vacuum chamber 21 and the adhesion prevention plate 29. In such a case, the anti-adhesion plate 29 is in an electrically floating state. Therefore, when plasma is generated in the vacuum chamber 21 and the target TG is sputtered, the plasma or the electrons are not easily affected by the ground potential (zero potential), and it is easy to stably seal between the target TG and the substrate SB. That is, when a piezoelectric film such as lead titanate zirconate is formed, the charge distribution of the piezoelectric film during film formation tends to be constant, and the quality of the film such as crystallinity is easily improved.

In this way, the film forming apparatus 20 of this embodiment mode does not arrange the conductive near the substrate SB (specifically, the distance from the substrate SB is 30 mm or less, preferably 25 mm or less, and more preferably 20 mm or less). The conductive member, or even if the conductive member is disposed in the vicinity of the substrate SB, is brought into an electrically floating state, and plasma or electrons can be stably enclosed between the target TG and the substrate SB. Based on this, the inventors of the present invention discovered for the first time that when a piezoelectric film such as lead titanate zirconate is formed, the charge distribution of the piezoelectric film in the film formation tends to be constant, and the quality of the film such as crystallinity is improved. The piezoelectric film is excellent in ferroelectricity and piezoelectricity. Thereby, in a film forming apparatus for forming a piezoelectric film containing lead titanate zirconate, a piezoelectric film having good quality such as crystallinity can be formed.

In addition, according to the present embodiment, the substrate holding portion 25 is supported by the supporting portion 26 in the electrically floating state of the vacuum chamber 21, so that the substrate SB held in the substrate holding portion 25 can be in an electrically floating state to the supporting portion 26 . With such double floating, the electric charge accumulated in the substrate SB during film formation can not escape to the ground potential. By this, a large amount of electric charge can be accumulated in the substrate, and as a result, a film with good crystallinity can be formed.

In other words, by floating the substrate SB by the support portion 26, the leakage of electrons from the substrate caused by the electrons of the plasma can be prevented. When a large amount of electric charge is accumulated on the substrate, the plasma will cause the electric charge from the substrate to escape to the ground potential or have the property of causing abnormal discharge, so a film with good crystallinity can be formed by suppressing it as much as possible.

In addition, by moving the conductive member connected to the ground potential away from the substrate SB, white turbidity of the piezoelectric film formed on the substrate can be eliminated.

The target holding unit 31 holds the target TG in the vacuum chamber 21. The target TG includes a backing plate BP1 and a target TM1 fixed to one side of the backing plate BP1. The surface of the target TG held by the target holding portion 31 faces the surface of the substrate SB. In the example shown in FIG. 8, the target holding portion 31 is provided below the substrate holding portion 25, the upper surface of the target TG held by the target holding portion 31 and the lower side of the substrate SB held by the substrate holding portion 25 Face to face.

The power supply unit 32 supplies high-frequency power to the target TG. By supplying high-frequency power to the target TG by the power supply unit 32, the target TG is sputtered. That is, the film forming apparatus 20 of this embodiment is an RF (Radio Frequency, Radio Frequency) sputtering apparatus.

The power supply unit 32 includes a high-frequency power supply 32a and an integrator 32b. It is appropriate that the high-frequency power supply 32a is a high-frequency power supply with pulse modulation function that modulates high-frequency power into a pulse shape. The high-frequency power supply 32a is connected to the integrator 32b, and the integrator 32b is connected to the back plate BP1 of the target TG. In the present embodiment, the power supply unit 32 supplies the high-frequency power to the target TG via the target holding unit 31, but the power supply unit 32 may directly supply the high-frequency power to the target TG.

In addition, the film forming apparatus may further include a V _DC control unit 33 that controls the voltage V _DC of the DC component generated at the target TG when the high-frequency power is supplied from the power supply unit 32 to -200 V or more and -80 V or less. The V _DC control unit 33 has a V _DC sensor and is electrically connected to the power supply unit 32.

A suitable one is the film forming apparatus 20, and has a magnet portion 34 and a magnet rotation driving portion 35. The magnet portion 34 is provided rotatably around the rotation axis RA1, for example. The magnet rotation drive unit 35 rotates the magnet unit 34 around the rotation axis RA1, and the magnet unit 34 is driven to apply a magnetic field to the target TG. That is, the film forming apparatus of this embodiment is an RF magnetron sputtering apparatus. In addition, the magnet portion 34 or the magnet rotation driving portion 35 is a magnetic field applying portion that applies a magnetic field to the target TG.

It is appropriate that the horizontal magnetic field on the surface of the target TG to which the magnetic field is applied (upper in the example shown in FIG. 8) is 140 to 220G. This is because if the horizontal magnetic field on the surface of the target TG is greater than 220G, the energy on the surface of the target TG becomes too high, and the entire film on the substrate becomes turbid. If it is smaller than 140G, the surface energy of the target TG becomes too small. The film-forming speed is reduced and becomes impractical, and the crystallinity is also reduced. When the horizontal magnetic field on the surface of the target TG is 140 G or more, plasma or electrons are stably enclosed near the surface of the target TG compared to the case where the magnetic flux density on the surface of the target TG is less than 140 G. On the other hand, when the horizontal magnetic field on the surface of the target TG is 220G or less, compared with the case where the horizontal magnetic field on the surface of the target TG exceeds 220G, plasma or electrons are not concentrated too much on the surface of the target TG. The density is enclosed. In addition, the magnetic field on the surface of the target TG is preferably along the surface of the target TG.

    <Manufacturing method of membrane structure>    

Next, a method of manufacturing the film structure of this embodiment will be described. 11 to 14 are cross-sectional views in the manufacturing steps of the membrane structure of the embodiment.

First, as shown in FIG. 11, the substrate 11 is prepared (step S1). In step S1, for example, a substrate 11 of a silicon substrate made of silicon (Si) single crystal is prepared. The substrate 11 composed of a silicon single crystal has a cubic crystal structure and has an upper surface 11a composed of a (100) plane as a main surface. When the substrate 11 is a silicon substrate, an oxide film such as a SiO ₂ film may be formed on the upper surface 11a of the substrate 11.

In addition, as the substrate 11, various substrates other than a silicon substrate, such as a SOI (Silicon on Insulator) substrate, a substrate composed of various semiconductor single crystals other than silicon, a substrate composed of various oxide single crystals such as sapphire, or the surface may be used A substrate or the like composed of a glass substrate formed with a polycrystalline silicon film.

As shown in FIG. 11, two directions orthogonal to each other in the upper surface 11a of the (100) plane of the substrate 11 made of silicon single crystal are taken as the X-axis direction and the Y-axis direction, and the direction perpendicular to the upper surface 11a is taken as the Z-axis direction .

Next, as shown in FIG. 12, an alignment film 12 is formed on the substrate 11 (step S2). In the following, in step S2, the case where the alignment film 12 is formed using the electron beam evaporation method will be described as an example, but it may also be formed using various methods such as a sputtering method.

In step S2, first, in a state where the substrate 11 is disposed in a certain vacuum atmosphere, the substrate 11 is heated to, for example, 700 ° C.

In step S2, next, Zr is evaporated by an electron beam vapor deposition method using a vapor deposition material of zirconium (Zr) single crystal. At this time, the evaporated Zr reacts with oxygen on the substrate 11 heated to 700 ° C., for example, to form a zirconium oxide (ZrO ₂ ) film. Next, an alignment film 12 composed of a ZrO ₂ film as a single-layer film is formed.

The alignment film 12 is epitaxially grown on the upper surface 11a of the substrate 11 made of a silicon single crystal composed of the (100) surface as the main surface. The alignment film 12 has a cubic crystal structure and contains (100) aligned zirconia (ZrO ₂ ). That is, on the upper surface 11a composed of the (100) plane of the substrate 11 composed of silicon single crystal, an alignment film 12 composed of a single-layer film containing (100) aligned zirconia (ZrO ₂ ) is formed.

As explained using FIG. 11 described above, the two directions orthogonal to each other in the upper surface 11a of the (100) plane of the substrate 11 made of silicon single crystal are taken as the X-axis direction and the Y-axis direction, which are perpendicular to the direction of the upper surface 11a As the Z axis direction. At this time, the epitaxial growth of a certain film means that the film is aligned in any of the X-axis direction, the Y-axis direction, and the Z-axis direction.

The alignment film 12 has a cubic crystal structure and includes (100) aligned zirconia film 12a (see FIG. 7). In this case, the zirconia film 12a is oriented along the <100> direction of the upper surface 11a as the main surface of the substrate 11 made of a silicon substrate of the zirconia film 12a, and the <100> direction of the upper surface 11a of the substrate 11 itself Align in parallel.

The thickness of the alignment film 12 is preferably 2-100 nm, and more preferably 10-50 nm. By having such a film thickness, epitaxial growth can be achieved, and the alignment film 12 very close to the single crystal can be formed.

Next, as shown in FIG. 4, the conductive film 13 is formed (step S3).

In this step S3, first, the conductive film 13 as a part of the lower electrode grown as the epitaxial on the alignment film 12 is formed. The conductive film 13 is made of metal. As the conductive film 13 made of metal, for example, a conductive film containing platinum (Pt) is used.

As the conductive film 13, when a Pt-containing conductive film is formed, the epitaxially grown conductive film 13 is formed as a part of the lower electrode on the alignment film 12 at a temperature of 450 to 600 ° C. by sputtering. The conductive film 13 containing Pt is epitaxially grown on the alignment film 12. In addition, Pt contained in the conductive film 13 has a cubic crystal structure and is (100) aligned.

The conductive film 13 has a cubic crystal structure and includes a (100) oriented platinum film 13a (see FIG. 7). In this case, the platinum film 13a is aligned so that the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the platinum film 13a becomes parallel to the <100> direction of the upper surface 11a of the substrate 11 itself .

In addition, as the conductive film 13 made of metal, instead of using a conductive film containing platinum (Pt), for example, a conductive film containing iridium (Ir) may be used instead.

In this step S3, the conductive film 13 is then heat-treated at a temperature of 450 to 600 ° C. Specifically, after the conductive film 13 is formed by sputtering at a temperature of 450 to 600 ° C, it is preferably maintained at 450 to 600 ° C for 10 to 30 minutes for heat treatment.

When the temperature of the heat-treated conductive film 13 is less than 450 ° C., the temperature is too low, the crystallinity of platinum contained in the conductive film 13 cannot be improved, and the piezoelectric film 15 formed on the conductive film 13 via the film 14 cannot be improved. Crystallinity. When the temperature of the heat-treated conductive film 13 exceeds 600 ° C, the temperature is too high, and the crystal grains of platinum contained in the conductive film 13 will grow, but the crystallinity of platinum cannot be improved, and the film formed on the conductive film 13 via the film 14 cannot be improved The crystallinity of the piezoelectric film 15. On the other hand, when the conductive film 13 is heat-treated at a temperature of 450 to 600 ° C., the crystallinity of platinum contained in the conductive film 13 can be improved, and the piezoelectric film 15 formed on the conductive film 13 via the film 14 can be improved Crystallinity.

In addition, in the case of heat-treating the conductive film 13 at a temperature of 450 to 600 ° C., it is preferable to maintain the heat treatment for 10 to 30 minutes. When the heat treatment time of the conductive film 13 is less than 10 minutes, the time is too short to improve the crystallinity of platinum contained in the conductive film 13 and the crystallinity of the piezoelectric film 15 formed on the conductive film 13 via the film 14 . When the temperature of the heat-treated conductive film 13 exceeds 30 minutes, the time is too long, and the crystal grains of platinum contained in the conductive film 13 will grow, but the crystallinity of platinum cannot be improved, and the film formed on the conductive film 13 via the film 14 cannot be improved The crystallinity of the piezoelectric film 15.

Next, as shown in FIG. 13, the film 14 is formed (step S4). In this step S4, a film 14 containing a composite oxide represented by the aforementioned general formula (Chemical Formula 4) is formed on the conductive film 13. As the composite oxide represented by the aforementioned general formula (chemical formula 4), for example, a conductive film containing strontium titanate (STO), strontium ruthenate titanate (STRO), or strontium ruthenium (SRO) can be formed. When the SRO-containing conductive film is formed as a composite oxide represented by the general formula (Chemical Formula 4), in step S4, a film 14 as a conductive film as a part of the lower electrode is formed on the conductive film 13. In addition, in the aforementioned general formula (Chemical Formula 4), z satisfies 0 ≦ z ≦ 1.

As the film 14, when a conductive film containing STO, STRO or SRO is formed, the epitaxially grown film 14 is formed as a part of the lower electrode on the conductive film 13 at a temperature of about 600 ° C by sputtering . The film 14 containing STO, STRO or SRO is epitaxially grown on the conductive film 13. In addition, the STO, STRO, or SRO contained in the film 14 is represented by a quasi-cubic crystal or a cubic crystal as (100) alignment.

The film 14 has a quasi-cubic crystal structure, and is an SRO film 14a (refer to FIG. 7) including (100) alignment. In this case, the SRO film 14a is aligned so that the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the SRO film 14a becomes parallel to the <100> direction of the upper surface 11a of the substrate 11 itself .

In addition, instead of the sputtering method, the film 14 can be formed by a coating method such as a sol-gel method. In this case, in step S4, first, by coating a solution containing strontium and ruthenium, strontium, titanium and ruthenium, or strontium and titanium on the film 14, a composite oxide containing the general formula (Chemical Formula 4) is formed. The precursor film. In addition, when the film 14 is formed by the coating method, in step S4, next, the precursor is oxidized and crystallized by heat treatment of the film to form the film 14 including the composite oxide represented by the general formula (Chemical Formula 4) .

Next, as shown in FIG. 14, the piezoelectric film 16 is formed (step S5). In this step S5, a piezoelectric film 16 containing a composite oxide composed of lead titanate zirconate (PZT) represented by the aforementioned general formula (Chemical Formula 6) is formed on the film 14 by, for example, a sputtering method. Here, in the aforementioned general formula (Chemical Formula 6), x satisfies 0.32 ≦ x ≦ 0.52.

Among them, when x satisfies 0.32 ≦ x ≦ 0.48, the PZT included in the piezoelectric film 16 originally had a crystal structure composed of rhombohedral crystals, mainly due to the binding force from the substrate 11 and the like, having crystals of tetragonal crystal Structure, and easy (001) alignment. Next, the piezoelectric film 16 containing PZT is epitaxially grown on the film 14. In addition, when x satisfies 0.48 <x ≦ 0.52, the PZT included in the piezoelectric film 16 is originally composed of a tetragonal crystal structure, and has a tetragonal crystal structure, and is (001) aligned. Next, the piezoelectric film 16 containing PZT is epitaxially grown on the film 14. Accordingly, the direction of the polarization axis of the lead titanate zirconate included in the piezoelectric film 16 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric characteristics of the piezoelectric film 16 can be improved.

The piezoelectric film 16 has a crystal structure of a tetragonal crystal, and is a lead titanate-zirconate film 16a (refer to FIG. 7) including (001) orientation. In this case, the lead titanate zirconate film 16a is oriented along the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the lead titanate zirconate film 16a and the <100> direction of the upper surface 11a of the substrate 11 itself Align in parallel.

For example, when the piezoelectric film 16 is formed by a sputtering method, each of the plural crystal grains 16g (see FIG. 5) included in the piezoelectric film 16 can be polarized by plasma. That is, each of the plural crystal grains 16g included in the piezoelectric film 16 to be formed has spontaneous polarization. In addition, the spontaneous polarizations included in each of the plurality of crystal grains 16g include a polarization component P1 parallel to the thickness direction of the piezoelectric film 16 (see FIG. 5). Next, the polarization components P1 included in the spontaneous polarizations included in each of the plurality of crystal grains 16g face the same direction. As a result, the formed piezoelectric film 16 has spontaneous polarization as the entire piezoelectric film 16 before polarization processing is performed.

That is, in step S5, when the piezoelectric film 16 is formed by sputtering, the piezoelectric film 16 can be polarized by plasma. As a result, as described using FIG. 6, when the film structure 10 of the present embodiment is used as a piezoelectric element, it is not necessary to perform polarization treatment on the piezoelectric film 16 before use.

In addition, in step S5, when the piezoelectric film 16 is formed by the sputtering method, for example, the piezoelectric film 16 expands due to the sputtering particles and argon (Ar) gas injection in the piezoelectric film 16, and the piezoelectric film 16 With compressive stress.

It is appropriate that in step S5, a film containing PZT as a composite oxide is formed at a temperature of 425 to 475 ° C and a film forming speed of 0.29 nm / s or less, and a pressure composed of the film formed is formed Electromembrane 16. Under such conditions, a membrane structure that satisfies the aforementioned formula (Expression 1) and Formula (Expression 2) can be easily obtained.

Alternatively, it is appropriate that, in step S5, an underlayer film containing PZT as a composite oxide is formed at a temperature of 425 to 475 ° C. and a first film formation rate of 0.29 nm / s or less. Next, an upper layer film containing PZT as a composite oxide is formed on the lower layer film at a temperature of 425 to 475 ° C and at a second film forming rate that is lower than the first film forming rate. Piezoelectric film 16 composed of an underlying film and an upper film. Under such conditions, a membrane structure that satisfies the aforementioned formula (Expression 1) and Formula (Expression 2) can be easily obtained.

Here, a film forming method for forming the piezoelectric film 16 using the film forming apparatus 20 described above using FIGS. 8 to 10 will be described.

First, the target holding portion 31 holds the target TG in the vacuum chamber 21.

Next, the substrate holding portion 25 holds the substrate SB in the vacuum chamber 21. As the substrate SB, for example, a film structure in which the alignment film 12, the conductive film 13, and the film 14 are formed on the substrate 11 can be used. The substrate holding portion 25 is supported by the supporting portion 26 attached to the vacuum chamber 21, and an insulating member 51 is interposed between the supporting portion 26 and the substrate holding portion 25 or between the vacuum chamber 21 and the supporting portion 26. In addition, the substrate holding portion 25 is in contact with the substrate holding portion 25 at the outer peripheral portion of the substrate SB, and holds the substrate SB in a state where the central portion of the substrate SB is separated from the substrate holding portion 25. The support portion 26 includes conductive members 41 and 42. The conductive members 41 and 42 are rotatably provided integrally with the substrate holding portion 25 around the rotation axis RA1. The conductive member 42 is in an electrically floating state. As a result, plasma or electrons are not easily affected by the ground potential (zero potential), and are easily and securely enclosed between the target TG and the substrate SB.

The substrate holding portion 25 includes an insulating member 25a that is formed of an insulating member and surrounds the substrate SB in a plan view, and an insulating member that is formed of an insulating member and faces the center side of the substrate SB in a plan view Plural protrusions 25b protruding respectively. The substrate holding portion 25 holds the substrate SB in a state where the outer peripheral portion (outer edge portion) of the lower surface of the substrate SB is in contact with the upper surface of each of the plurality of protruding portions 25b. Thereby, when the substrate heating portion 28 heats the substrate SB, it is possible to prevent or suppress the actual temperature of the central portion of the substrate SB from deviating from the target temperature.

Next, the substrate SB is heated by the substrate heating portion 28, the conductive members 41 and 42 are rotationally driven by the rotation driving portion 27, the magnetic field is applied to the target TG by the magnet portion 34, and the target TG is supplied with high power by the power supply portion 32 In the state of high frequency power, the piezoelectric film 16 is formed on the surface of the substrate SB by sputtering the surface of the target TG in the vacuum chamber 21.

In addition, the film forming apparatus 20 forms the piezoelectric film 16 by attaching the surface of the target TG and the film forming material to the surface of the substrate SB by sputtering, and at this time, the conductive film installed in the vacuum chamber 21 The anti-adhesion plate 29 composed of a sexual member prevents the film-forming material from adhering to the substrate holding portion 25. Between the anti-adhesion plate 29 and the vacuum chamber 21, an insulating member 55 is interposed, and the anti-adhesion plate 29 is in an electrically floating state. As a result, plasma or electrons are not easily affected by the ground potential (zero potential), and are easily and securely enclosed between the target TG and the substrate SB.

Next, as shown in FIG. 1, the piezoelectric film 17 is formed (step S6). In this step S6, the piezoelectric film 17 containing the composite oxide composed of lead zirconate titanate (PZT) represented by the general formula (Chemical Formula 7) is applied on the piezoelectric film 16 by, for example, the sol-gel method, etc. Formed by the coating method. Hereinafter, a method of forming the piezoelectric film 17 by the sol-gel method will be described.

In step S6, first, a film containing PZT precursor is formed by applying a solution containing lead, zirconium, and titanium on the piezoelectric film 16. In addition, the step of applying a solution containing lead, zirconium, and titanium may be repeated a plurality of times, thereby forming a film including a plurality of films stacked on each other.

In step S6, next, the precursor is oxidized and crystallized by heat-treating the film to form a piezoelectric film 17 including PZT. Here, in the aforementioned general formula (Chemical Formula 7), y satisfies 0.32 ≦ y ≦ 0.48.

However, when y satisfies 0.32 ≦ y ≦ 0.48, the PZT included in the piezoelectric film 17 originally has a crystal structure of rhombohedral crystals, mainly due to the binding force from the substrate 11 and the like, and has crystals of tetragonal crystals Structure, and easy (001) alignment. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16. In addition, when y satisfies 0.48 <y ≦ 0.52, the PZT included in the piezoelectric film 17 is originally composed of a tetragonal crystal structure, and has a tetragonal crystal structure, and is (001) aligned. Next, the piezoelectric film 17 containing PZT is epitaxially grown on the piezoelectric film 16. Thereby, the direction of the polarization axis of the lead titanate zirconate included in the piezoelectric film 17 can be aligned approximately perpendicular to the upper surface 11a, so that the piezoelectric characteristics of the piezoelectric film 17 can be improved.

The piezoelectric film 17 has a crystal structure of a tetragonal crystal, and is a lead titanate zirconate film 17a (refer to FIG. 7) including (001) orientation. In this case, the lead titanate zirconate film 17a is oriented along the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the lead titanate zirconate film 17a and the <100> direction of the upper surface 11a of the substrate 11 itself Align in parallel.

When the PZT having a tetragonal crystal structure is (001) aligned, the polarization direction parallel to the [001] direction and the electric field direction parallel to the thickness direction of the piezoelectric film 15 are parallel to each other, so piezoelectric characteristics are improved. That is, when PZT having a tetragonal crystal structure is applied with an electric field in the [001] direction, piezoelectric constants d ₃₃ and d ₃₁ with large absolute values can be obtained. Therefore, the piezoelectric constant of the piezoelectric film 15 can be further increased. In addition, in this specification, the piezoelectric constant d _{31 may have} a negative sign, but the negative sign may be omitted and the absolute value may be used.

In step S6, for example, by evaporating the solvent in the solution during the heat treatment or narrowing the film when the precursor is oxidized and crystallized, the piezoelectric film 17 has tensile stress.

In this way, the piezoelectric film 15 including the piezoelectric film 16 and the piezoelectric film 17 is formed, and the film structure 10 shown in FIG. 1 is formed. That is, step S5 and step S6 are included in the conductive film 13 with the interlayer 14 to form a titanic zirconate containing tetragonal crystals represented by (001) alignment or pseudo-cubic crystals represented by (100) alignment and epitaxial growth The steps of the piezoelectric film 15 of lead.

Next, by X-ray diffraction measurement using the θ-2θ method, the diffraction pattern of the piezoelectric film 15 is measured (step S7).

The piezoelectric film 15 has a crystal structure of a tetragonal crystal, and when it contains lead titanate zirconate of (001) orientation, in this embodiment, the piezoelectric film 15 according to the θ-2θ method using CuKα line X In the line diffraction pattern, the diffraction angle of the diffraction peak of the (004) plane represented by the tetragonal crystal of lead titanate zirconate is 2θ ₀₀₄ , 2θ ₀₀₄ satisfies the following formula (Equation 1).

2θ ₀₀₄ ≦ 96.5 ° ‧‧‧ (Equation 1)

By this, the interval of the (004) plane represented by the tetragonal crystal of lead titanate zirconate becomes longer. Or, the piezoelectric film 15 has a tetragonal crystal structure, and the content of (001) aligned lead zirconate titanate can be higher than that of the piezoelectric film 15 with a tetragonal crystal structure, and (100) alignment The content of lead titanium zirconate is even greater. That is, the polarization directions of the plurality of crystal grains included in the piezoelectric film 15 can be aligned, so that the piezoelectric characteristics of the piezoelectric film 15 can be improved.

On the other hand, when the piezoelectric film 15 includes PZT whose (100) orientation is represented by a quasi-cubic crystal, in this embodiment, the X-ray diffraction of the piezoelectric film 15 according to the θ-2θ method using CuKα line When the diffraction angle of the diffraction peak of the (400) plane represented by the pseudo-cubic crystal of lead titanate zirconate is 2θ ₄₀₀ , 2θ ₄₀₀ satisfies the aforementioned formula (Equation 1), and it replaces 2θ ₀₀₄ and is replaced by 2θ ₄₀₀ The formula (2θ ₄₀₀ ≦ 96.5 °).

In addition, in the present embodiment, when the relative dielectric constant of the piezoelectric film 15 is ε _r , ε _r satisfies the following formula (Expression 2).

ε _r ≦ 450‧‧‧ (Equation 2)

Accordingly, when the membrane structure 10 is used as a pressure sensor using a piezoelectric effect, for example, the detection sensitivity can be improved, and the detection circuit of the pressure sensor can be easily designed. Alternatively, when the membrane structure 10 is used, for example, as an ultrasonic vibrator using an inverse piezoelectric effect, an oscillation circuit can be easily designed.

After the piezoelectric film 17 is formed, a conductive film 18 (see FIG. 2) as an upper electrode may be formed on the piezoelectric film 17 (step S8). With this, an electric field can be applied to the piezoelectric film 17 in the thickness direction.

In addition, after the conductive film 18 is formed, an AC voltage having a frequency of 1 kHz is applied between the conductive film 13 and the conductive film 18 to measure the relative dielectric constant (step S9).

It is appropriate that when the film structure 10 has the conductive film 18, when the relative dielectric constant of the piezoelectric film 15 measured by applying an alternating voltage having a frequency of 1 kHz between the conductive film 13 and the conductive film 18 is ε _r , the pressure The ε _{r of the} electrical film 15 satisfies the aforementioned formula (equation 2).

By reducing the relative dielectric constant under an alternating voltage having such a frequency, for example, the clock frequency of the detection circuit can be increased, and the response speed of the pressure sensor using the membrane structure 10 can be increased.

Relevance of those residual extremum points of the piezoelectric film 15 when P _r, P _r satisfy the following equation (Equation 3).

P _r ≧ 28μC / cm ² ‧‧‧ (Equation 3)

With this, the ferroelectric characteristics of the piezoelectric film 15 can be improved, so the piezoelectric characteristics of the piezoelectric film 15 can also be improved.

In addition, between the film 14 and the piezoelectric film 15, a film containing lead zirconate titanate may be formed. The film may be represented by the aforementioned general formula (Chemical Formula 8) and may include a composite oxide represented by (100) alignment in a pseudocubic crystal.

    <Modified example of implementation form>    

In the embodiment, as shown in FIG. 1, the piezoelectric film 15 including the piezoelectric film 16 and the piezoelectric film 17 is formed. However, the piezoelectric film 15 may include only the piezoelectric film 16. Such an example will be described as a modification of the embodiment.

Fig. 15 is a cross-sectional view of a membrane structure according to a modification of the embodiment.

As shown in FIG. 15, the film structure 10 of this modification includes a substrate 11, an alignment film 12, a conductive film 13, a film 14, and a piezoelectric film 15. The alignment film 12 is formed on the substrate 11. The conductive film 13 is formed on the alignment film 12. The film 14 is formed on the conductive film 13. The piezoelectric film 15 is formed on the film 14. The piezoelectric film 15 includes the piezoelectric film 16.

That is, in the film structure 10 of this modification, the piezoelectric film 15 does not include the piezoelectric film 17 (see FIG. 1), and only includes the piezoelectric film 16, and is the same as the film structure 10 of the embodiment. .

When the piezoelectric film 15 includes the piezoelectric film 16 with compressive stress, but does not include the piezoelectric film 17 with tensile stress (see FIG. 1), the piezoelectric film 15 and the piezoelectric film 16 with compressive stress and Compared with the case where all piezoelectric films 17 (see FIG. 1) having tensile stress are included, the amount of warpage of the film structure 10 is increased. However, for example, when the thickness of the piezoelectric film 15 is very thin, the amount of warpage of the film structure 10 can be reduced. Therefore, even when the piezoelectric film 15 includes only the piezoelectric film 16, the shape accuracy can be improved, for example, when the film structure 10 is processed using a photoetching technique, and the characteristics of the piezoelectric element formed by processing the film structure 10 can be improved .

In addition, the film structure 10 of the present modification example may have the conductive film 18 (see FIG. 2) as in the film structure 10 of the embodiment.

    [Example]    

Hereinafter, the present embodiment will be described in detail based on the embodiments. In addition, the present invention is not limited by the following examples.

    (Example 1 and Comparative Example 1)    

In the following, the film structure 10 described with reference to FIG. 1 in the embodiment is formed as the film structure of Example 1. FIG. In the film structure of Example 1, according to the X-ray diffraction pattern of the piezoelectric film 15 using the θ-2θ method of CuKα line, the diffraction peak of the diffraction peak of the (004) plane represented by the tetragonal crystal of lead titanate zirconate When the angle is 2θ ₀₀₄ , 2θ ₀₀₄ satisfies the aforementioned expression (Equation 1). In addition, in the film structure of Example 1, when the relative dielectric constant of the piezoelectric film 15 is ε _r , ε _r satisfies the aforementioned formula (Expression 2). On the other hand, 2θ ₀₀₄ is that the film structure that satisfies the aforementioned formula (Expression 1) is the film structure of Comparative Example 1.

The method of forming the film structure of Example 1 will be described below. In addition, in the method of forming the film structure of Comparative Example 1, when the piezoelectric film 16 is formed using an RF sputtering device, the supplied high-frequency power (power) is 2750 W, which is different from the supplied high-frequency power (power) The conditions of Example 1 which is 2250W are different.

First, as shown in FIG. 11, as the substrate 11, the upper surface 11 a composed of the (100) plane as the main surface is prepared, and a wafer composed of 6-inch silicon single crystal is prepared.

Next, as shown in FIG. 12, on the substrate 11, as the alignment film 12, a zirconium oxide (ZrO ₂ ) film is formed by an electron beam evaporation method. The conditions at this time are shown below.

Device: Electron beam evaporation device

Pressure: 7.00 × 10 ^-3 Pa

Evaporation source: Zr + O ₂

Accelerating voltage / radiation current: 7.5kV / 1.80mA

Thickness: 24nm

Film forming speed: 0.005nm / s

Oxygen flow: 7sccm

Substrate temperature: 500 ℃

Next, as shown in FIG. 4, on the alignment film 12, a platinum (Pt) film is formed as the conductive film 13 by sputtering. The conditions at this time are shown below.

Device: DC sputtering device

Pressure: 1.20 × 10 ^-1 Pa

Evaporation source: Pt

Electricity: 100W

Thickness: 150nm

Film forming speed: 0.14nm / s

Ar flow rate: 16sccm

Substrate temperature: 450 ~ 600 ℃

Next, the Pt film is heat-treated. The conditions at this time are shown below.

Device: DC sputtering device

Substrate temperature (heat treatment temperature): 450 ~ 600 ℃

Heat treatment time: 10 ~ 30 minutes

Next, as shown in FIG. 13, on the conductive film 13, an SRO film is formed as a film 14 by sputtering. The conditions at this time are shown below.

Device: RF magnetron sputtering device

Power: 300W

Gas: Ar

Pressure: 1.8Pa

Substrate temperature: 600 ℃

Film forming speed: 0.11nm / s

Thickness: 20nm

Next, as shown in FIG. 14, on the film 14, as the piezoelectric film 16, a Pb (Zr _0.58 Ti _0.42 ) O ₃ film (PZT film) having a film thickness of 1 μm was formed by a sputtering method. The conditions at this time are shown below.

Device: RF magnetron sputtering device

Power: 2250W

Gas: Ar / O ₂

Pressure: 0.6Pa

Substrate temperature: 425 ℃

Film forming speed: 0.29nm / s

Ar flow rate: 66sccm

Oxygen flow: 6sccm

Film formation time: 4200s

Next, as shown in FIG. 1, on the piezoelectric film 16, as the piezoelectric film 17, a Pb (Zr _0.58 Ti _0.42 ) O ₃ film (PZT film) was formed by a coating method. The conditions at this time are shown below.

The organometallic compounds of Pb, Zr and Ti are mixed so as to have a composition ratio of Pb: Zr: Ti = 100 + δ: 58: 42, and the mixed solvent of ethanol and 2-n-butoxy alcohol is used as Pb ( Zr _0.58 Ti _0.42 ) The raw material solution to be dissolved is adjusted so that the concentration of O ₃ becomes 0.35 mol / l. For δ, δ = 20. Next, 20 g of polypyrrolidone with a K value of 27 to 33 was dissolved in the raw material solution.

Next, 3 ml of the raw material solution in the prepared raw material solution was dropped onto the substrate 11 composed of a 6-inch wafer, and rotated at 3000 rpm for 10 seconds. By applying the raw material solution on the substrate 11, a precursor containing the precursor was formed. Of the membrane. Next, by placing the substrate 11 on a hot plate at a temperature of 200 ° C for 30 seconds, and further mounting the substrate 11 on a hot plate at a temperature of 450 ° C for 30 seconds, the solvent is evaporated to dry the film . Thereafter, the precursor is oxidized by heat treatment at 600 to 700 ° C. for 60 seconds in an oxygen (O ₂ ) atmosphere of 0.2 MPa to crystallize, thereby forming a piezoelectric film 17 having a thickness of 30 nm.

For each of Example 1 and Comparative Example 1, the θ-2θ spectrum according to the XRD method of the film structure up to the PZT film formed as the piezoelectric film 17 was measured. That is, for each of Example 1 and Comparative Example 1, X-ray diffraction measurement by the θ-2θ method was performed.

Each of FIGS. 16 to 19 is a diagram showing an example of the θ-2θ spectrum of the film structure formed up to the PZT film according to the XRD method. The horizontal axis of the graphs of FIGS. 16 to 19 shows the angle 2θ, and the vertical axis of the graphs of FIGS. 16 to 19 shows the intensity of the X-ray. 16 and 17 show the results for Example 1, and FIGS. 18 and 19 show the results for Comparative Example 1. 16 and 18 show the range of 20 ° ≦ 2θ ≦ 50 °, and FIGS. 17 and 19 show the range of 90 ° ≦ 2θ ≦ 110 °.

In the examples shown in FIGS. 16 and 17 (Example 1), in the θ-2θ spectrum, the peaks corresponding to the (200) and (400) planes of Pt having a cubic crystal structure, and the equivalent to having a square The peaks of the (001) plane, (002) plane, and (004) plane of PZT displayed by the crystal are observed. Therefore, it can be seen that in the examples shown in FIGS. 16 and 17 (Example 1), the conductive film 13 includes a crystal structure having a cubic crystal and (100) aligned Pt, and the piezoelectric film 15 includes a cubic crystal shown as (001) Aligned PZT.

In addition, in the example shown in FIG. 17 (Example 1), when the diffraction angle of the diffraction peak of the (004) plane represented by the square crystal of PZT is 2θ ₀₀₄ , it is 2θ ₀₀₄ = 96.5 °. Therefore, in the example shown in FIGS. 16 and 17 (Embodiment 1), 2θ ₀₀₄ satisfies 2θ ₀₀₄ ≦ 96.5 °, and it can be seen that the foregoing expression (Expression 1) is satisfied.

Even the example shown in FIGS. 18 and 19 (Comparative Example 1) is the same as the example shown in FIGS. 16 and 17 (Example 1). In the θ-2θ spectrum, it corresponds to a crystal structure with cubic crystals. The peaks of the (200) plane and (400) plane of Pt, and the peaks corresponding to the (001) plane, (002) plane, and (004) plane of PZT having a square crystal display are observed. Therefore, even in the example shown in FIGS. 18 and 19 (Comparative Example 1), the conductive film 13 includes a crystal structure having a tetragonal crystal as in the example shown in FIGS. 16 and 17 (Example 1), and (100) Pt with alignment, the piezoelectric film 15 includes PZT with cubic crystals showing (001) alignment.

However, in the example shown in FIG. 19 (comparative example), unlike the example shown in FIG. 17 (Example 1), when the diffraction angle of the diffraction peak of the (004) plane represented by the square crystal of PZT is 2θ ₀₀₄ , It is 2θ ₀₀₄ = 96.7 °. Therefore, in the example shown in FIGS. 18 and 19 (Comparative Example 1), it can be seen that 2θ _{004 does} not satisfy 2θ ₀₀₄ ≦ 96.5 °, and does not satisfy the foregoing expression (Expression 1).

For Example 1, the measurement of the pole figure according to the XRD method was performed, and the relationship of the alignment in the plane of the film of each layer was investigated. Each of FIGS. 20 to 23 is a diagram showing an example of the pole figure according to the XRD method of the film structure of Example 1. FIG. Fig. 20 is a pole diagram of the Si (220) plane, Fig. 21 is a pole diagram of the ZrO ₂ (220) plane, Fig. 22 is a pole diagram of the Pt (220) plane, and Fig. 23 is a pole diagram of the PZT (202) plane.

As described above, the alignment film 12 has a cubic crystal structure and includes (100) aligned zirconia film 12a (see FIG. 7). In this case, as shown in FIGS. 20 and 21, it can be understood that the zirconia film 12a is oriented along the <100> direction of the upper surface 11a of the main surface of the substrate 11 made of a silicon substrate of the zirconia film 12a as the main surface. The top of 11 itself is aligned in such a way that the <100> direction of 11a becomes parallel. In other words, it can be understood that the zirconia film 12a is oriented along the <110> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the zirconia film 12a as the main surface, and the <110> of the upper surface 11a of the substrate 11 itself The directions are aligned in a parallel manner.

In addition, the conductive film 13 has a cubic crystal structure and includes a (100) aligned platinum film 13a (see FIG. 7). In such a case, as shown in FIGS. 20 and 22, it can be understood that the platinum film 13a is oriented along the <100> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the platinum film 13a and the upper surface 11a of the substrate 11 itself. The <100> direction is aligned so that the direction becomes parallel. In other words, it can be understood that the platinum film 13a is aligned in such a manner that the <110> direction of the upper surface 11a of the substrate 11 made of the silicon substrate of the platinum film 13a becomes parallel to the <110> direction of the upper surface 11a of the substrate 11 itself With.

In addition, the piezoelectric film 15 has a crystal structure of a tetragonal crystal and is a lead titanium zirconate film 15a with (001) orientation. In this case, as shown in FIGS. 20 and 23, it can be understood that the lead titanate zirconate film 15a is along the <100> direction of the upper surface 11a of the substrate 11 made of the silicon substrate of the lead titanium zirconate film 15a, and The top of 11 itself is aligned in such a way that the <100> direction of 11a becomes parallel. In other words, it can be understood that the lead titanate zirconate film 15a follows the <110> direction of the upper surface 11a of the substrate 11 made of a silicon substrate of the lead titanate zirconate film 15a, and the <110> of the upper surface 11a of the substrate 11 itself The directions are aligned in a parallel manner.

For Example 1, a film structure was formed on each of the 17 wafers of No. 1 to No. 17 under the same conditions up to the PZT film as the piezoelectric film 17, and the thickness of the formed film structure was measured According to θ-2θ spectrum of XRD method. That is, the X-ray diffraction measurement according to the θ-2θ method was performed on the 17 membrane structures as Example 1.

24 is a diagram showing the diffraction angle 2θ ₀₀₄ of the respective X-ray diffraction patterns formed on the film structures of the 17 wafers as No. 1 to No. 17 of Example 1. FIG. In FIG 24, a structure for diffraction angle 2θ ₀₀₄ of the film, the central portion of the diffraction angle 2θ ₀₀₄ shown in the left side of the wafer, the wafer outer peripheral portion of the diffraction angle of 2θ ₀₀₄ displayed on the right.

As shown in FIG. 24, the film structures formed on each of the 17 wafers of Example 1 had a diffraction angle 2θ ₀₀₄ greater than 95.9 ° but less than 96.4 °. That is, it can be seen that, as the 17 wafers of Example 1, the diffraction angle 2θ ₀₀₄ satisfies the aforementioned expression (Equation 1).

In addition, for Example 1, a film structure was formed on each of the 12 wafers of No. 21 to No. 32 under the same conditions up to the PZT film as the piezoelectric film 17, and the formed film was measured Θ-2θ spectrum of the structure according to XRD method. That is, the X-ray diffraction measurement according to the θ-2θ method was performed on the twelve film structures as Example 1.

FIG. 25 is a diagram showing the diffraction angle 2θ ₀₀₄ of the respective X-ray diffraction patterns formed on the film structures of the 12 wafers of No. 21 to No. 32 of Example 1. FIG. In FIG. 25, FIG. 24 and also for a structure of the diffraction angle 2θ ₀₀₄ film, the central portion of the diffraction angle 2θ ₀₀₄ shown in the left side of the wafer, the wafer outer peripheral portion of the diffraction angle of 2θ ₀₀₄ shown in Right.

As shown in FIG. 25, the film structures formed on each of the 12 wafers in Example 1 had a diffraction angle 2θ ₀₀₄ greater than 96.0 ° but less than 96.25 °. That is, it can be seen that, as the 17 wafers of Example 1, the diffraction angle 2θ ₀₀₄ satisfies the aforementioned expression (Equation 1).

In addition, in the θ-2θ spectrum of FIG. 18 and FIG. 19, the square crystal of PZT is represented as the high-angle side of the (00n) plane (n is a natural number), and a peak is observed. This should be because, for example, the (100) alignment portion of the PZT having a tetragonal crystal structure has a slight content rate, and this portion functions as a stress relaxation layer.

Next, as shown in FIG. 2, a platinum (Pt) film is formed on the piezoelectric film 15 as a conductive film 18 by sputtering. Thereafter, a voltage was applied between the conductive film 13 and the conductive film 18 to measure the voltage dependence of the polarization.

26 is a graph showing the voltage dependence of the polarizing of the film structure of Example 1. FIG. FIG. 27 is a graph showing the voltage dependence of the polarizing of the film structure of Comparative Example 1. FIG. The horizontal axis of the graphs of FIGS. 26 and 27 shows the voltage, and the vertical axis of the graphs of FIGS. 26 and 27 shows the polarities (the same is true for the following graphs showing the voltage dependence of the polarities).

According to FIG. 26, in the film structure of Example 1 of the embodiment, the relative dielectric constant ε _r was 450 or less (measured value 450), the residual extremum points P _r is ² or more (Found ^{28μC / cm 2) 28μC / cm} . In addition, when the cantilever is formed and the piezoelectric constant d ₃₁ is measured using the formed cantilever, the piezoelectric constant d ₃₁ is 200 pm / V.

On the other hand, according to FIG. 27, in the film structure of Comparative Example 1, the relative dielectric constant ε _r than 450 (measured value 800), the remaining points of extreme value P _r is less than 28μC / cm ² (Found 10μC / cm ² ). Further, in Example 1 measured the piezoelectric constant d _31, the piezoelectric constant of d ₃₁ 140pm / V. As described above, in the method of forming the film structure of Comparative Example 1, when the piezoelectric film 16 is formed using an RF sputtering device, the supplied high-frequency power (power) is 2750 W, which is different from the supplied high-frequency power The conditions of Example 1 which is 2250W are different.

That is, according to Example 1 and Comparative Example 1, it can be understood that when the high-frequency power supplied when forming the piezoelectric film 16 in the film structure of the present embodiment is within a certain range, the relative dielectric constant ε _r satisfies the foregoing Formula (Expression 2), the residual sub-extremum _Pr satisfies the aforementioned Formula (Expression 3). Here, in the following, the film structures of Example 2 to Example 9 and Comparative Example 2 are formed, and the relative dielectric constant ε _r satisfies the aforementioned formula (equation 2), and the residual fractional extreme Pr satisfies the aforementioned formula (numerical value) Condition of formula 3).

    (Example 2 and Example 3)    

In the manufacturing method of the film structure of Example 1, except that the substrate temperature at the time of forming the piezoelectric film 16 was changed from 425 ° C to 450 ° C, it was carried out in the same manner as the manufacturing method of the film structure of Example 1, forming an example 2. The membrane structure. In addition, the manufacturing method of the film structure of Example 1 was performed in the same manner as the manufacturing method of the film structure of Example 1, except that the substrate temperature when forming the piezoelectric film 16 was changed from 425 ° C to 475 ° C. The film structure of Example 3.

With respect to the film structures of Example 2 and Example 3, voltage was applied between the conductive film 13 and the conductive film 18, and the voltage dependence of polarization was measured. 28 is a graph showing the voltage dependence of the polarizing of the film structure of Example 2. FIG. 29 is a graph showing the voltage dependence of the polarizing of the film structure of Example 3. FIG.

According to FIG. 28, in the film structure of Example 2 of the embodiment, the relative dielectric constant ε _r was 450 or less, residual extremum points P _r is ² or more (Found ^{41μC / cm 2) 28μC / cm} . Further, according to FIG. 29, in the film structure of Example 3, the relative dielectric constant ε _r was 450 or less, residual extremum points P _r is ² or more (Found ^{45μC / cm 2) 28μC / cm} .

That is, according to Examples 1 to 3, when the supplied high-frequency power is 2250 W, the substrate temperature when the piezoelectric film 16 is formed is in the range of 425 to 475 ° C., and a relative dielectric constant of 450 or less can be obtained ε _r, ² or more can be obtained residue 28μC / cm extremum points P _r. Although detailed description is omitted, when the substrate temperature when forming the piezoelectric film 16 is less than 425 ° C, or when the substrate temperature when forming the piezoelectric film 16 exceeds 475 ° C, a relative dielectric constant of 450 or less is required. ε _r is difficult.

    (Example 4 and Example 5)    

The manufacturing method of the film structure of Example 1 is the same as the manufacturing method of the film structure of Example 1, except that the high-frequency power (power) supplied when forming the piezoelectric film 16 is changed from 2250W to 2000W. The film structure of Example 4 was formed. At this time, the film formation rate was 0.20 nm / s, which was smaller than 0.29 nm / s in Example 1.

In addition, the manufacturing method of the film structure of Example 1 is the same as the manufacturing method of the film structure of Example 1, except that the high-frequency power (power) supplied when forming the piezoelectric film 16 is changed from 2250W to 1750W. In this way, the film structure of Example 5 was formed. At this time, the film formation rate was 0.17 nm / s, which was smaller than 0.29 nm / s in Example 1.

With respect to the film structures of Example 4 and Example 5, the voltage dependence of the polarization was measured by applying a voltage between the conductive film 13 and the conductive film 18. 30 is a graph showing the voltage dependence of the polarizing of the film structure of Example 4. FIG. 31 is a graph showing the voltage dependence of the polarizing of the film structure of Example 5. FIG.

According to FIG. 30, in the film structure of Example 4 embodiment, the relative dielectric constant ε _r was 450 or less, residual extremum points P _r is ² or more 28μC / cm (Found 45μC / cm ^2). Further, according to FIG. 31, in the film structure of Example 5, the relative permittivity ε _r was 450 or less, the residual fraction of the extreme value P _r 28μC / cm ² or more (Found 50μC / cm ^2).

That is, according to Example 1, Example 4, and Example 5, it can be seen that when the substrate temperature is 425 ° C, the high-frequency power supplied when the piezoelectric film 16 is formed is in the range of 1750-2250W, and the following 450 can be obtained relative permittivity ε _r, ² or more can be obtained residue 28μC / cm extremum points P _r. This should be the range of high-frequency power in the range of 1750 ~ 2250W. The smaller the value of high-frequency power, the slower the film-forming speed. The piezoelectric film 16 slowly crystallizes and grows. the residue extremum points P _r sake.

    (Example 6 to Example 8 and Comparative Example 2)    

The manufacturing method of the film structure in Example 1 is the same as the manufacturing method of the film structure in Example 1, except that the value of the high-frequency power (power) supplied when forming the piezoelectric film 16 is changed from 2250W to 2500W. In this way, the film structure of Comparative Example 2 was formed. These conditions are shown in Figure 32. 32 is a table for the measurement results of the film formation conditions of Example 1, Example 6 to Example 8, Comparative Example 1 and Comparative Example 2, and the diffraction angle 2θ ₀₀₄ and relative dielectric constant ε _{r of} PZT. .

In addition, in the manufacturing method of the film structure of Example 1, except for the high-frequency power (power) supplied when the piezoelectric film 16 is formed, the high-frequency power supplied in the subsequent step is higher than that in the previous step The method of supplying high-frequency power with a smaller value is divided into multiple steps to change the value and supply it. It is carried out in the same manner as the manufacturing method of the film structure of Example 1, and the film structures of Examples 6 to 8 are formed. body.

In this way, the reason why the high-frequency power is divided into multiple steps and its value is supplied is because the step of forming the piezoelectric film 16 reduces the value of the initially supplied high-frequency power and reduces the film-forming speed. Will reduce the sake. On the other hand, by only slowly growing the upper layer portion of the piezoelectric film 16, as a whole, a good single-crystal piezoelectric film 16 can be obtained at a relatively fast film forming speed, and good ferroelectricity can be obtained.

Specifically, in the manufacturing method of the film structure of Example 6, among the steps of forming the piezoelectric film 16, in the first step, the value of the supplied high-frequency power is 2250W, and the substrate temperature is 450 ° C. The film formation time was 2100 s, and a Pb (Zr _0.58 Ti _0.42 ) O ₃ film (underlayer PZT film) with a film thickness of 500 nm was formed. Next, in the step of forming the piezoelectric film 16, in the second step, the value of the supplied high-frequency power was 2000 W, the substrate temperature was 450 ° C., and the film formation time was 2300 s. Pb with a film thickness of 500 nm was formed. (Zr _0.58 Ti _0.42 ) O ₃ film (upper layer PZT film). With this, the piezoelectric film 16 composed of the lower PZT film and the upper PZT film is formed. These conditions are shown in Figure 32. In addition, in FIG. 32, as the high-frequency power, only the value of the step of forming the upper layer PZT film (2000W) is shown.

In addition, in the manufacturing method of the film structure of Example 7, among the steps of forming the piezoelectric film 16, in the first step, the value of the supplied high-frequency power was set to 2250W, and the substrate temperature was 450 ° C to form a film. The time was 4200s, and a Pb (Zr _0.58 Ti _0.42 ) O ₃ film (lower layer PZT film) with a film thickness of 1 μm was formed. Next, in the step of forming the piezoelectric film 16, in the second step, the value of the supplied high-frequency power was 1750W, the substrate temperature was 450 ° C, and the film formation time was 2300 s. Pb with a film thickness of 500 nm was formed (Zr _0.58 Ti _0.42 ) O ₃ film (intermediate PZT film). Furthermore, among the steps of forming the piezoelectric film 16, in the third step, the value of the supplied high-frequency power was 1750 W, the substrate temperature was 425 ° C., and the film formation time was 2300 s. Pb with a film thickness of 500 nm was formed. (Zr _0.58 Ti _0.42 ) O ₃ film (upper layer PZT film). With this, the piezoelectric film 16 composed of the lower layer PZT film, the middle layer PZT film, and the upper layer PZT film is formed. The total film-forming time is 8800s. These conditions are shown in Figure 32. In addition, in FIG. 32, as the high-frequency power, only the value of the step of forming the upper layer PZT film (1750W) is shown.

In addition, in the manufacturing method of the film structure of Example 8, among the steps of forming the piezoelectric film 16, in the first step, the value of the supplied high-frequency power was 1750 W, and the substrate temperature was 450 ° C. to form a film. The time was 2300 s, and a Pb (Zr _0.58 Ti _0.42 ) O ₃ film (lower layer PZT film) with a film thickness of 500 nm was formed. Next, in the step of forming the piezoelectric film 16, in the second step, the value of the supplied high-frequency power was 1750W, the substrate temperature was 425 ° C, and the film formation time was 2100s, forming Pb with a film thickness of 400 nm (Zr _0.58 Ti _0.42 ) O ₃ film (intermediate PZT film). Furthermore, among the steps of forming the piezoelectric film 16, in the third step, the value of the supplied high-frequency power was 1500W, the substrate temperature was 475 ° C, and the film formation time was 900 s. Pb having a film thickness of 100 nm (Zr _0.58 Ti _0.42 ) O ₃ film (upper layer PZT film). With this, the piezoelectric film 16 composed of the lower layer PZT film, the middle layer PZT film, and the upper layer PZT film is formed. The total film-forming time is 5300s. These conditions are shown in Figure 32. In addition, in FIG. 32, as the high-frequency power, only the value of the step of forming the upper layer PZT film (1500W) is shown.

For each of Examples 6 to 8, the θ-2θ spectrum according to the XRD method of the film structure up to the PZT film formed as the piezoelectric film 17 was measured. That is, for each of Examples 6 to 8, X-ray diffraction measurement by the θ-2θ method was performed.

Each of Figs. 33 to 35 is a diagram showing an example of the θ-2θ spectrum of the film structure formed up to the PZT film according to the XRD method. The horizontal axis of the graphs of FIGS. 33 to 35 shows the angle 2θ, and the vertical axis of the graphs of FIGS. 16 to 19 shows the intensity of the X-ray. Figure 33 shows the results for Example 6, Figure 34 shows the results for Example 7, and Figure 35 shows the results for Example 8. In addition, FIGS. 33 to 35 show the range of 90 ° ≦ 2θ ≦ 110 °.

Furthermore, 2θ ₀₀₄ obtained in FIGS. 17, 19, and 33 to 35 is shown in FIG. 32. Although the illustration of the θ-2θ spectrum is omitted, the film structure of Comparative Example 2 also shows 2θ ₀₀₄ obtained by measuring the θ-2θ spectrum by the XRD method in FIG. 32.

As shown in FIGS. 33 to 35 and 32, in the membrane structure of Example 6, 2θ ₀₀₄ = 96.4 °, the membrane structure of Example 7 2θ ₀₀₄ = 96.1 °, the membrane structure of Example 8, 2θ ₀₀₄ = 95.9 °. In addition, as described above, in the film structure of Example 1, 2θ ⁰⁰⁴ = 96.5 °, although detailed description is omitted, in the film structure of Examples 2 to 5, 2θ ₀₀₄ satisfies 2θ ₀₀₄ ≦ 96.5 °. Therefore, in the film structures of Examples 1 to 8, 2θ ₀₀₄ satisfies 2θ ₀₀₄ ≦ 96.5 °, and it can be seen that the aforementioned formula (Expression 1) is satisfied.

In addition, with respect to the film structures of Comparative Example 2 and Examples 6 to 8, the voltage dependence of the polarization was measured by applying a voltage between the conductive film 13 and the conductive film 18. 36 is a graph showing the voltage dependence of the polarizing of the film structure of Comparative Example 2. FIG. 37 is a graph showing the voltage dependence of the polarizing of the film structure of Example 6. FIG. 38 is a graph showing the voltage dependence of the polarizing of the film structure of Example 7. FIG. 39 is a graph showing the voltage dependence of the polarizing of the film structure of Example 8. FIG.

The case of FIG. 36 and FIG. 32, in the film structure of Comparative Example 2, the relative dielectric constant ε _r than 450 (measured value 580), the remaining points of extreme value P _r is less than 28μC / cm ² (Found 18μC / cm ² ). In addition, when the cantilever is formed and the piezoelectric constant d ₃₁ is measured using the formed cantilever, the piezoelectric constant d ₃₁ is 178 pm / V.

The case of FIG. 37 and FIG. 32, in the film structure of Example 6 of the embodiment, the relative dielectric constant ε _r was 450 or less (measured value 330), the residual extremum points P _r is ² or more (Found 28μC / cm 39μC / cm ² ). Further, in Comparative Example measured the piezoelectric constant d 2 _31, the piezoelectric constant of d ₃₁ 210pm / V.

Further, according to the case of FIG. 38 and FIG. 32, in the film structure of Example 7, the relative dielectric constant ε _r was 450 or less (measured value 263), the residual extremum points P _r is ² or more (Found 28μC / cm 48μC / cm ² ). Further, in Comparative Example measured the piezoelectric constant d 2 _31, the piezoelectric constant of d ₃₁ 220pm / V.

Further, according to the case of FIG. 39 and FIG. 32, in the film structure of Example 8 embodiment, the relative dielectric constant ε _r was 450 or less (measured value 216), the residual extremum points P _r is ² or more (Found 28μC / cm 57μC / cm ² ). Further, in Comparative Example measured the piezoelectric constant d 2 _31, the piezoelectric constant of d ₃₁ 230pm / V.

That is, if according to Examples 1 to Example 8, to meet the relative permittivity ε _r ε _r ≦ 450, extrema points P _r satisfy the remaining P _r ≧ 28μC / cm ^2, satisfies the piezoelectric constant d ₃₁ d ₃₁ ≧ 200pm / V, it can be seen that the aforementioned formula (formula 1) and formula (formula 2) are satisfied.

As described above, PZT, like PbTiO ₃ , improves the crystallinity of the alignment including the thin film, so that the relative dielectric constant becomes low. That is, in Examples 1 to 8, the relative dielectric constant ε _{r is as} low as 450 or less, and the piezoelectric film 15 becomes single crystal.

The piezoelectric phenomenon is a phenomenon in which a charge due to the deformation is generated in the piezoelectric body due to the lattice deformation of the piezoelectric body when stress is applied to the piezoelectric body. That is, piezoelectric deformation divides the charge density generated by the piezoelectric body by the value of the stress applied to the piezoelectric body. In the case where the piezoelectric body is a ferroelectric, it is proportional to the residual partial extreme value.

In addition, the capacity of the capacitor composed of the dielectric and the two electrodes formed on the upper and lower sides of the dielectric is proportional to the relative permittivity of the dielectric and the area of each of the two electrodes. The thickness, that is, the distance between the two electrodes is inversely proportional. In this case, as compared with the case where the charge is generated when stress is applied to the piezoelectric body, the piezoelectric deformation is proportional to the relative permittivity of the dielectric body composed of the piezoelectric body.

In Comparative Example 1 and Comparative Example 2 and Example 1 and Example 6 to Example 8, when the product (P _r ‧ε _r ) of the residual partial extreme value Pr and the relative dielectric constant ε _r is obtained, as shown in FIG. 32 It shows that the value of P _r ‧ε _{r has} a good proportional relationship with the piezoelectric constant d ₃₁ . That is, as described above, piezoelectric deformation was confirmed, proportional to the residual sub-extremum value, and proportional to the relative dielectric constant.

In addition, the broken surface was observed by SEM. As a result, detailed descriptions are omitted, and the piezoelectric film 16 has good single crystallinity compared to Examples 1 and 6 to 8; in Comparative Examples 1 and 2, the piezoelectric film 16 and the edge Between two crystal grains adjacent in the direction of the main surface, cracks (cracking) extending in the thickness direction of the piezoelectric film 16 were observed, and it was found that the single crystallinity of the piezoelectric film 15 decreased. In FIG. 32, the case where cracks are observed is indicated by ×, and the case where cracks are not observed is indicated by ○.

From the above results, it can be seen that the piezoelectric film included in the film structure can obtain a piezoelectric film composed of a high-quality single-crystal film by satisfying the aforementioned formula (equation 1) and formula (equation 2), reducing The relative dielectric constant of the film can also improve the piezoelectric characteristics of the piezoelectric film, so that the piezoelectric characteristics of the piezoelectric film can be improved, and the detection sensitivity of the pressure sensor using the piezoelectric film can be improved.

    (Example 9 and Example 10)    

The film structure of Example 9 was formed in the same manner as the manufacturing method of the film structure of Example 1. In addition, in the manufacturing method of the membrane structure of Example 1, except that the composition of PZT was changed from x = 0.42 to x = 0.48, it was carried out in the same manner as the manufacturing method of the membrane structure of Example 1, forming Example 10 Membrane structure. With respect to the film structures of Example 9 and Example 10, a voltage was applied between the conductive film 13 and the conductive film 18, and the voltage dependence of polarization was measured. 40 is a graph showing the voltage dependence of the polarizing of the film structure of Example 9. FIG. 41 is a graph showing the voltage dependence of the polarizing of the film structure of Example 10. FIG.

In addition, the results of the measurement of the ferroelectric characteristics and piezoelectric characteristics of Example 9 and Example 10 are shown in Table 2. In Table 2, show residual extremum points P _r, the relative dielectric constant ε _r, dielectric tangent tan [delta], the piezoelectric constant d _31, the piezoelectric constant g _31, a piezoelectric constant e ₃₁ and the film thickness. In addition, in Table 2, the piezoelectric constant d ₃₁ , the piezoelectric constant g _31, and the piezoelectric constant e ₃₁ are indicated not by absolute values but by signs.

As shown in FIG. 40 and Table 2, in the case where x = 0.42 (Example 9), the residual fraction of the extreme value P _r 50μC / cm ^2, the relative permittivity ε _r of 200, tanδ 0.01%, a piezoelectric constant d ₃₁ is -200 pm / V, the piezoelectric constant g ₃₁ is -100 × 10 ³ Vm / N, and the piezoelectric constant e ₃₁ is -25 C / m ² , and good characteristics are obtained. Further, as shown in FIG. 41 and Table 2, even in the case of x = 0.48, P _r is the residual extremum points 60μC / cm ^2, the relative permittivity ε _r of 300, tanδ 0.01%, a piezoelectric constant d ₃₁ It is -250 pm / V, the piezoelectric constant g ₃₁ is -80 × 10 ³ Vm / N, and the piezoelectric constant e ₃₁ is -27C / m ² , and good characteristics are obtained. In addition, although detailed description is omitted, good characteristics can be obtained when the value of x is changed within the range of 0.32 ≦ x ≦ 0.52. From the above results, it is clear that when x = 0.42 and 0.48 are included, good characteristics can be obtained in the range of 0.32 ≦ x ≦ 0.52.

The invention made by the inventor of the present application has been specifically described above based on its embodiment form, but the present invention is not limited to the aforementioned embodiment form, and of course various changes can be made without departing from the gist thereof.

Within the scope of the idea of the present invention, as long as the skilled person (professor) is familiar with it, various modifications and amendments may be conceived, and these modifications and amendments should also be understood to fall within the scope of the present invention.

For example, for each of the aforementioned embodiments, those who are familiar with the art make appropriate additions, reductions, or design changes to the components, or who add, omit, or change the conditions of the steps, as long as they have the gist of the present invention. It is included in the scope of the present invention.

Claims (22)

    A film forming apparatus characterized by having a vacuum chamber electrically connected to a ground potential, a target disposed in the vacuum chamber, a power supply unit that supplies high-frequency power to the target, and a gas supply that supplies gas to the vacuum chamber A portion, an insulating substrate holding portion arranged in the vacuum chamber to hold the substrate opposed to the target, a conductive supporting portion supporting the insulating substrate holding portion, the conductive supporting portion and the vacuum chamber The first insulating member between; the conductive support portion is electrically floating to the vacuum chamber by the first insulating member, and the outer peripheral portion of the substrate is in contact with the insulating substrate holding portion, the substrate is The insulating substrate holding portion is held in an electrically floating state with respect to the conductive support portion, and the insulating substrate holding portion does not overlap the central portion of the substrate in plan view.         A film-forming device according to item 1 of the patent application scope, which has a conductive anti-adhesion plate disposed between the target and the substrate at a distance within 30 mm from the substrate, the conductive anti-adhesion plate The chamber is in an electrically floating state.         For example, in the film-forming device of claim 2, the aforementioned conductive anti-adhesion plate is water-cooled.         A film forming apparatus as claimed in claim 2 or 3 includes a second insulating member disposed between the vacuum chamber and the conductive anti-adhesion plate.     A film forming apparatus as described in any of claims 1 to 4, wherein the contact area between the substrate and the insulating substrate holding portion is 20 mm ² or less.     The film forming apparatus according to any one of claims 1 to 5, wherein the corner of the insulating substrate holding portion has a curved surface.         The film forming apparatus according to any one of claims 1 to 6, wherein the conductive support portion includes a first conductive member that supports the insulating substrate holding portion, and the first conductive member includes the first The shaft is centered to be integrally rotatable with the insulating substrate holding portion, has a third insulating member disposed between the first conductive member and the insulating substrate holding portion, and the film forming device further has The rotational drive portion of the first conductive member is rotationally driven.         The film forming apparatus according to any one of claims 1 to 6, wherein the conductive support portion includes a second conductive member that supports the insulating substrate holding portion, and the second conductive member includes the second The shaft is centered and can be rotated integrally with the insulating substrate holding portion; the first insulating member is interposed between the vacuum chamber and the second conductive member, and the second conductive member is in an electrically floating state, The film forming apparatus further includes a rotation driving section that rotationally drives the second conductive member.         A film forming apparatus as claimed in item 7 of the patent application, which includes a substrate heating portion that heats the substrate, the third insulating member has a surrounding portion surrounding the substrate in plan view, and the insulating substrate holding portion has The plurality of protruding portions each protruding toward the central side of the substrate, and the insulating substrate holding portion holds the substrate in a state where the outer peripheral portion of the substrate is in contact with each of the plurality of protruding portions.         The film-forming apparatus according to any one of claims 1 to 9, which has a target holding portion that holds the target in the vacuum chamber, and a magnetic field applying portion that applies a magnetic field to the target; the target to which the magnetic field is applied The horizontal magnetic field on the surface is 140 ~ 220G.         For example, in the film-forming device of claim 10, the magnetic field on the surface of the target is along the surface of the target.         A film forming apparatus as claimed in any one of claims 1 to 11, wherein the film forming apparatus forms lead titanate zirconate on the surface of the substrate by sputtering the surface of the target containing lead titanate zirconate Of the film.         A film forming apparatus as claimed in any one of claims 1 to 12, wherein the film forming apparatus is formed under the substrate by sputtering in the vacuum chamber on the target upper surface that is arranged to face the substrate underneath membrane.         A film forming method characterized in that it is in a vacuum chamber that is conductively connected to a ground potential, the outer peripheral portion of the substrate is in contact with an insulating substrate holding portion, the insulating substrate holding portion holds the substrate, and the vacuum A film is formed on the surface of the substrate by sputtering the surface of the target in the room, the insulating substrate holding portion is supported by a conductive support portion in an electrically floating state to the vacuum chamber, and the substrate is electrically connected to the conductive support portion In the floating state, the plan view of the insulating substrate holding portion does not overlap the central portion of the substrate.         As in the film forming method of claim 14, the conductive anti-adhesion plate is arranged between the target and the substrate, the conductive anti-adhesion plate is located within a distance of 30 mm from the substrate, and the conductive anti-adhesion The board is electrically floating to the aforementioned vacuum chamber.         For example, in the film forming method of claim 14, the aforementioned conductive anti-adhesion plate is water-cooled.     The film forming method according to any one of the patent application items 14 to 16, wherein the contact area between the substrate and the insulating substrate holding portion is 20 mm ² or less.     A film forming method according to any one of patent application items 14 to 17, wherein a magnetic field is applied to the target by a magnetic field applying section, and in a state where high-frequency power is supplied to the target by an electric power supply section, by The surface of the target is sputtered, the film is formed on the surface of the substrate, and the horizontal magnetic field on the surface of the target to which the magnetic field is applied is 140 to 220G.         As in the film forming method of claim 18, the magnetic field on the surface of the target is along the surface of the target.         A film forming method as claimed in any one of claims 14 to 19, wherein the target contains lead titanate zirconate, and the film containing lead titanate zirconate is formed on the surface of the substrate by sputtering the surface of the target .     A film forming method as claimed in item 20 of the patent application, wherein the aforementioned substrate includes: a silicon substrate including a main surface composed of (100) planes, formed on the aforementioned main surface, having a cubic crystal structure, and including ( 100) The first film of the aligned zirconia film, and the first conductive film formed on the first film, having a cubic crystal structure, and including the (100) aligned platinum film; the zirconia film, along The <100> direction of the main surface of the zirconia film is aligned parallel to the <100> direction of the main surface of the silicon substrate; the platinum film is oriented along the main surface of the platinum film The <100> direction is aligned parallel to the <100> direction along the main surface of the silicon substrate; by sputtering the surface of the target, a crystal structure having a tetragonal crystal is formed on the first conductive film, And the first piezoelectric film including the (001) -aligned first lead zirconate titanate film, the first lead zirconate titanate film has a first lead zirconate titanate represented by the following general formula (chemical formula 1) a composite _{oxide, Pb (Zr 1-x Ti} x) O 3 ‧‧‧ ( chemical formula 1) the first lead zirconate titanate , Aligned so that the <100> direction of the main surface of the first lead zirconate titanate film is parallel to the <100> direction of the main surface of the silicon substrate; the x satisfies 0.32 ≦ x ≦ 0.52 .     The film-forming method according to any one of the patent application items 14 to 21, wherein a film is formed on the underside of the substrate by sputtering in the vacuum chamber on the target above the target disposed opposite to the underside of the substrate.