JP2006265651A - Film of composite perovskite type compound, method for forming the film, and method for producing liquid discharge head using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a film of a lead and titanium-containing composite perovskite type compound having a controlled composition at high precision by sputtering. <P>SOLUTION: The method for forming a film of a composite perovskite type compound comprises: a stage (a) where electric power is fed to a first target comprising lead and titanium as constituting elements, so as to sputter the components comprised in the first target; a stage (b) where electric power is fed to a second target comprising elements having a sputtering rate of ≤0.5 or ≥1.2 based on titanium as constituting elements, so as to sputter the components comprised in the second target; and a stage (c) where the components sputtered from the first and second targets are stuck to a substrate heated to a prescribed temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a film forming method for forming a film of a multi-component material containing a composite perovskite compound by sputtering. Furthermore, the present invention relates to a method for manufacturing a liquid discharge head (inkjet head) using such a film forming method.

  A structure in which electrodes are formed at both ends of a piezoelectric body is used in various applications such as a piezoelectric actuator, a piezoelectric pump, an ink head of an ink jet printer, and an ultrasonic transducer. In recent years, along with the development of MEMS (microelectromechanical system) related devices, miniaturization and integration of elements having such a structure are progressing. Therefore, miniaturization and improvement in performance are also desired for the piezoelectric body used there.

  In recent years, it is known that a ferroelectric substance (PNN-PZT) having high piezoelectric characteristics can be obtained by adding various elements to PZT (Pb (lead) zirconate titanate). However, in order to obtain high characteristics in such a compound, it is important to control the composition of elements constituting the compound.

  As a related technique, Patent Document 1 discloses that in order to obtain a PZT thin film having a predetermined composition and crystal structure, 300 P of power is supplied to three PZT targets, and 0 to 450 W of power is supplied to one PbO target. The film is deposited on the substrate while rotating the substrate holder at a speed of 30 rpm. Lead is adjusted so that the substrate temperature is 700 ° C. or higher and the Pb / (Zr + Ti) ratio in the film is 1 or higher. Controlling the substrate incident atomic flux ratio is disclosed.

  However, in Patent Document 1, the object of manufacture is limited to the PZT thin film, and no mention is made of the case where elements other than lead, titanium, zirconium, and oxygen are included. Therefore, since it is considered that the controllability of the composition is deteriorated when a film containing constituent elements other than the above elements is formed, it is difficult to apply the PZT thin film manufacturing method disclosed in Patent Document 1. Become. Further, since three or more targets are used, the apparatus becomes complicated.

Patent Document 2 discloses that in order to obtain a large piezoelectric displacement in a piezoelectric thin film, the chemical composition is Pb _{1 + a} (Zr _x Ti _1-x ) O _{3 + a} (where 0.2 ≦ a ≦ 0.6, 0.50). ≦ x ≦ 0.62), a perovskite columnar crystal region having an ion deficiency in which some of its constituent elements, oxygen ion, titanium ion, and zirconium ion, are missing, and a stoichiometric composition without ion deficiency A piezoelectric thin film made of a mixture with a perovskite columnar crystal region is disclosed.

  In Patent Document 3, when a Pb-based ferroelectric is formed by sputtering, the time required for stabilizing the ferroelectric component when the PbO powder is added to the ferroelectric powder for component adjustment is shortened. In order to achieve this, it is disclosed that a target for forming a Pb-based ferroelectric by sputtering is to mix and sinter Pb-based ferroelectric powder and PbO powder having an average particle size of 10 μm or less. Yes.

  In the above Patent Documents 2 and 3, in order to obtain a desired composition in the formed film, one target in which lead element is increased in advance is used. Moreover, the composition of the elements other than lead is adjusted at the target. However, according to such a film forming method, the composition of the formed film varies depending on the film forming conditions. In addition, in the case where a material having a significantly different sputtering rate is included in the target, the composition of the formed film is greatly deviated from the composition of the target. Therefore, the composition of the film cannot be controlled very well. In addition, depending on the composition of the target, there may be a problem in the sinterability during target fabrication.

Patent Document 4 discloses a composite perovskite-type compound Pb (Ni _1/3 Nb _2/3 ) O ₃ and a simple perovskite-type compound PbTiO ₃ and PbZrO in order to realize a large amount of strain while suppressing the non-dielectric constant low. _In the porcelain composition mainly composed of ₃ , Pb (Ni _1/3 Nb _2/3 ) O ₃ , PbTiO ₃ , PbZrO ₃ among the triangular coordinates having apex, Pb (Ni _1/3 Nb _2/3 ) When O ₃ is X mol%, PbTiO ₃ is Y mol%, and PbZrO ₃ is Z mol% (where X + Y + Z = 1), the composition range is point A (X = 40, Y = 37, Z = 23) , B point (X = 36, Y = 37, Z = 27), C point (X = 33, Y = 40, Z = 27) and D point (X = 37, Y = 40, Z = 23) On the line connecting the composition points and the area surrounded by these four points The piezoelectric ceramic composition is disclosed consisting mainly of circumference.

Patent Document 5, in order to actuators and miniaturization of the sensors and densification, the ceramic _substrate, in _{PbMg 1/3 Nb 2/3 O 3 -PbZrO 3} -PbTiO 3 ternary solid solution system composition, generally From a porcelain composition containing as a main component a composition represented by the formula Pb _x (Mg _{y / 3} Nb _2/3 ) _a Ti _b Zr _c O ₃ and containing 0.05 to 10.0% by weight of NiO in the total composition. There is disclosed a piezoelectric element provided with a piezoelectric body and an electrode electrically connected to the piezoelectric body, and the piezoelectric body is fixed to the ceramic substrate directly or via the electrode.

In Patent Document 6, in a piezoelectric ceramic composition used as an actuator material, xPb (Sb _1/2 Nb _{1/2) is used} in order to increase the amount of piezoelectric displacement in a high electric field and decrease the temperature change of the dielectric constant. ) In the three-component lead zirconate titanate (PZT) expressed as O ₃ —yPbZrO ₃ —zPbTiO ₃ , 0.96 ≦ y / z ≦ 1.39, 0 <x ≦ 11 mol% (where x + y + z = 100 mol%) It is disclosed that.

  In the above Patent Documents 4 to 6, it is proposed to improve the performance of the piezoelectric material by mixing other elements with PZT, but forming a film having such a composition with good reproducibility by sputtering. Is not disclosed.

Furthermore, Non-Patent Document 1 reports that 0.91Pb (Zn _1/3 Nb _2/3 ) O ₃ -0.09PbTiO ₃ (PZN-PT-based material) single crystal exhibits a high piezoelectric constant. However, a method for forming a thin film having such a composition is not disclosed.
JP-A-6-57412 (first page, FIG. 2) WO2002 / 29129 (first page, FIG. 1) JP-A-6-81138 (first page, FIG. 2) JP 2004-59369 A (first page, FIG. 1) JP 2004-153252 A (first page) Japanese Unexamined Patent Publication No. 2004-67437 (first page, FIG. 1) Kuwata et al., “Dielectric and Piezoelectric Properties of 0.91Pb (Zn1 / 3Nb2 / 3) O3-0.09PbTiO3 Single Crystals), Japanese Journal of Applied PHYSICS (JAPANESE JOURNAL OF APPLIED PHYSICS: JJAP), Vol. 21, No. 9, September 1982, p. 1298-1302

Thus, conventionally, there is no known method for accurately controlling the composition when a piezoelectric film of a composite perovskite compound containing lead and titanium is formed by sputtering.
Accordingly, in view of the above points, the present invention provides a film forming method for forming a film of a complex perovskite compound containing lead and titanium, the composition of which is precisely controlled, by sputtering, and such a composition. A first object is to provide a film of a composite perovskite type compound formed by using a film method. It is a second object of the present invention to provide a method for manufacturing a liquid discharge head using a piezoelectric film formed by such a film forming method.

  In order to solve the above problems, a composite perovskite film according to the present invention is composed of four or more elements including lead (Pb), titanium (Ti), and oxygen (O), and is formed by sputtering. A film of a composite perovskite compound, which includes a fourth element having a sputtering rate of 0.5 or less or 1.2 or more when the sputtering rate of titanium is used as a reference, and the fourth element in the film The fluctuation range of the composition distribution depending on the molar ratio is 10% or less.

  Further, the film forming method according to the present invention is a method of forming a film of a composite perovskite compound composed of four or more elements including lead (Pb), titanium (Ti), and oxygen (O) by sputtering. The step (a) of sputtering the components contained in the first target by supplying electric power to the first target containing lead and titanium as constituent elements, and 0 when titanium is used as a reference. (B) Sputtering the components contained in the second target by supplying electric power to the second target containing a fourth element having a sputtering rate of 5 or less or 1.2 or more as a constituent element And (c) attaching the components sputtered from the first and second targets to a substrate heated to a predetermined temperature.

  The method for manufacturing a liquid discharge head according to the present invention is defined by a diaphragm plate, a partition wall, and a nozzle plate provided with discharge ports, and includes a pressure chamber filled with liquid and a liquid in the pressure chamber. A method of manufacturing a liquid discharge head having a piezoelectric actuator that vibrates a diaphragm for discharging from a discharge port, wherein power is supplied to a first target containing lead and titanium as constituent elements. Sputtering components contained in the target and supplying power to the second target containing a fourth element having a sputtering rate of 0.5 or less or 1.2 or more as a constituent element when titanium is used as a reference. The step (a) of sputtering the component contained in the second target and the component sputtered from the first and second targets at a predetermined temperature A step (b) of forming a piezoelectric film on the substrate, a step (c) of forming an electrode on the piezoelectric film, and a diaphragm on the electrode. A step (d), a step (e) for forming a partition for defining a pressure chamber on the diaphragm, and a step (f) for forming a nozzle plate provided with a discharge port on the partition. It comprises.

  In the present application, the sputtering rate means the number of atoms (atoms / ion) sputtered when one ion collides with the target.

  According to the present invention, among the constituent elements of the composite perovskite type compound, an element whose sputtering rate is significantly different from that of titanium is disposed on a target different from titanium, and the power supplied to the plurality of targets is controlled. However, since the components sputtered from these targets are attached to the substrate, the composition of the formed film can be accurately controlled regardless of the sputtering rate of the constituent elements. Thereby, the function (for example, piezoelectric performance) of the film of the composite perovskite compound can be increased. Accordingly, it is possible to improve the performance of a device such as a liquid discharge head that uses a piezoelectric actuator including the piezoelectric film formed as described above.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a schematic diagram showing a configuration of a film forming apparatus in which a film forming method according to an embodiment of the present invention is used. The film forming method according to the present embodiment is a method of forming a piezoelectric film of a composite perovskite compound by sputtering.

  The film forming apparatus shown in FIG. 1 includes a film forming chamber 1, an exhaust pump 2, a substrate holder 3, a substrate holder driving unit 4, a reactive gas supply unit 5, two target holding units 6 and 7, and a high frequency. Power sources (RF) 8 and 9 and two matching boxes (MB) 10 and 11 are included.

The film forming chamber 1 is connected to a ground wiring. The exhaust pump 2 evacuates the film forming chamber 1 to keep the inside at a predetermined degree of vacuum.
The substrate holder 3 is a holder for holding the substrate 20 on which a film is formed, and is installed in the film forming chamber 4 in a rotatable state. The substrate holder 3 is provided with a heater for keeping the substrate 20 at a predetermined temperature.
The substrate holder driving unit 4 rotates the substrate holder 3 so that the substrate 20 held by the substrate holder 3 rotates in the main surface.
The reactive gas supply unit 5 supplies a reactive gas such as argon (Ar) or oxygen (O ₂ ) into the film forming chamber 1, for example.

  The target holders 7 and 8 are, for example, magnetron cathodes having a diameter of about 4 inches, and hold sputtering targets (hereinafter simply referred to as targets) 21 and 22, respectively. The target holding unit 7 is connected to a high frequency power source 8 through a matching box 10, and the target holding unit 8 is connected to a high frequency power source 9 through a matching box 11.

  The high frequency power supplies 8 and 9 are power supply devices that generate an alternating voltage having a frequency of 13.56 MHz, for example. The matching boxes 10 and 11 match impedances between the load and the high frequency power supplies 8 and 9 by canceling the reactance component of the load. As the matching boxes 10 and 11, for example, a matching box using a blocking capacitor can be used. The blocking capacitor cuts the DC component and passes only the AC component.

  In such a film forming apparatus, the substrate 20 is set on the substrate holder 3, the substrate is kept at a predetermined temperature, and targets 21 and 22 containing predetermined elements are set on the target holding portions 7 and 8, respectively. Further, a reactive gas is introduced into the film forming chamber 1 from the reactive gas supply unit 5. Then, while driving the substrate holder driving unit 4 and rotating the substrate holder 3, electric power of a predetermined magnitude is supplied to the target holding units 7 and 8, respectively. Thereby, the component sputtered from the target 21 and the component sputtered from the target 22 are sequentially attached to the substrate 20. As a result, a film containing the elements contained in the targets 21 and 22 as constituent elements is formed on the substrate 20.

Next, the principle of the film forming method according to one embodiment of the present invention will be described.
In general, the composition of a film formed by sputtering consists of (i) the amount of atoms jumping out of the target into the gas phase, (ii) the amount of atoms in the gas phase adhering to the substrate, and (iii) adhering to the substrate. It depends on the amount of atoms sputtered again. Among these, the amount of atoms in (i) and (iii) is an amount determined according to the sputtering rate.

Here, a case where a composite perovskite compound containing lead (Pb), nickel (Ni), niobium (Nb), zirconium (Zr), and titanium (Ti) is formed by sputtering will be considered. Table 1 shows the sputtering rates of the above elements with respect to argon ions (Ar ⁺ ) having an energy of 300 eV, and values obtained by normalizing the sputtering rates with the sputtering rates of titanium. In addition, the sputtering rate in Table 1 is extracted from a vacuum handbook (Nihon Vacuum Technology Edit, published by Ohmsha). Further, as disclosed in JP-A-6-49638 (page 4), the composition of lead (Pb) is self-controlled so as to become an optimum value by being excessively mixed into the target. Therefore, in the present embodiment, the composition is excluded from the target to be controlled.

  As shown in Table 1, the sputtering rate varies depending on the type of element. For this reason, if an element whose sputtering rate is significantly different from other elements is included in one target, the sputtered components will vary regardless of the composition of the target. As a result, the composition ratio of a plurality of elements in the target is not reflected in the composition ratio of the formed film, and a film having a desired composition cannot be manufactured. For example, when an element such as nickel, which has a sputtering rate significantly higher than other elements (for example, a normalized value of 1.2 or more, preferably 1.5 or more) is included in the target, Since elements are preferentially sputtered, the composition ratio of other elements is relatively lowered. On the other hand, when an element having a significantly lower sputtering rate than other elements (for example, a normalized value of 0.5 or less) is included in the target, the other elements are preferentially sputtered. The composition ratio of the element is lowered.

  Therefore, in the present embodiment, a plurality of types of elements constituting the film to be formed are arranged in a plurality of targets according to the sputtering rate, and the power supplied to each of these targets is adjusted. Sputtering is performed. Thereby, the composition ratio in the formed film is controlled.

  In this embodiment, the sputtering rate of titanium (Ti) contained in any perovskite type compound is used as a reference for determining the constituent elements to be arranged on each target. Specifically, an element whose sputtering rate is significantly smaller than titanium (for example, a normalized value is 0.5 or less), or an element whose sputtering rate is significantly larger than titanium (for example, a normalized value) Is 1.2 or more, preferably 1.5 or more) is placed on a target other than titanium.

Example 1
As a first example, a film was formed for the purpose of forming a 0.2Pb (Ni _1/3 Nb _2/3 ) O ₃ -0.8Pb (Zr _0.5 Ti _0.5 ) O ₃ film.
As shown in Table 1, among the main elements (other than lead) constituting this film, nickel (Ni) has a greatly different sputtering rate. Therefore, two targets having the following composition were prepared by placing only nickel on another target.
First target: oxide sintered body having a composition ratio (molar ratio) of Pb: Nb: Zr: Ti = 1.2: 0.13: 0.4: 0.4 Second target: NiO sintering body

  Note that the first target may not be a composition having a stoichiometric composition (stoichiometry), and the composition may be appropriately adjusted. Further, the second target may be an oxide target as described above or a metal target. Further, a lead element may be added to the second target. This is because the composition ratio of lead is self-controlled in the formed film as described above.

These first and second targets were placed on the target holding units 6 and 7 of the film forming apparatus shown in FIG. The film formation conditions at that time are as follows.
Substrate ... Pt (200 nm) / Ti (50 nm) / Si
Substrate temperature ... 600 ° C
Deposition chamber pressure: 0.5 Pa
Power supplied to the first target ... 400W
Supply power to the second target: variable In the substrate, the platinum layer formed on the silicon via the titanium layer is provided as a diffusion preventing layer between the piezoelectric film and the silicon. This is because lead contained in the piezoelectric film easily reacts with silicon. The titanium layer is provided to improve the adhesion between the silicon and the platinum layer.
Under such conditions, a film having a thickness of about 10 μm was formed by performing sputtering while changing the power supplied to the second target.

  On the other hand, as a comparative example, a sintered body having a composition ratio (molar ratio) of Pb: Ni: Nb: Zr: Ti = 1.2: 0.066: 0.13: 0.4: 0.4 was prepared. By using this as a target and performing sputtering, a film having a thickness of about 10 μm was formed. The film formation conditions such as the substrate, the substrate temperature, and the pressure in the film formation chamber were the same as those in Example 1, and the power supplied to the target was 400 W.

When the membranes obtained by the examples and comparative examples were analyzed, the results shown in the following (1) to (4) were obtained. In the composition analysis, an energy dispersive X-ray analyzer (EDX) was used.
(1) Dependence of nickel composition ratio on supply power As shown in FIG. 2, in the film obtained in Example 1, composition ratio of nickel and titanium with respect to supply power to the second target (Ni / Ti composition ratio) ) Dependency. That is, it was confirmed that the nickel composition ratio in the formed film was controlled by the power supplied to the second target.

(2) Composition ratio of constituent elements In the film obtained in Example 1, when the power supplied to the second target is 40 W, the composition ratio of the constituent elements is Pb: Ni: Nb: Zr: Ti = 1: 0.07: 0.14: 0.39: 0.41, confirming that a value relatively close to the target was obtained.
On the other hand, in the film obtained by the comparative example, the composition ratio is Pb: Ni: Nb: Zr: Ti = 1: 0.03: 0.14: 0.38: 0.4, and the composition of nickel The ratio deviated greatly from the target value.

(3) Piezoelectric characteristics A cantilever structure was prepared using the films obtained in Example 1 and the comparative example, and the piezoelectric performance was measured. As a result, in the film obtained in Example 1, the piezoelectric characteristic d31 = 190 pm / V was obtained, and it was confirmed that excellent piezoelectric performance was exhibited. On the other hand, in the film | membrane obtained by the comparative example, piezoelectric characteristic d31 = 110pm / V was obtained, and it turned out that the piezoelectric performance is inferior compared with the Example.

(4) Composition variation The variation width of the composition distribution in the thickness direction in the films obtained in Example 1 and the comparative example was examined. The fluctuation range of the composition distribution was calculated by extracting 10 points at 1 μm intervals in the thickness direction in the cross section of the film, measuring the composition distribution at each point, and using the following formula (1). In the formula (1), the composition _max is the maximum value in the 10 locations of the composition ratio of a certain constituent element, and the composition _min is the minimum value in the 10 locations of the composition ratio according to the molar ratio of the constituent elements. .
Fluctuation width = (composition _max −composition _min ) × 100 / (composition _max + composition _min ) (1)

  As a result, in the film obtained in Example 1, the variation width of the composition distribution of the constituent elements other than oxygen was 10% or less, desirably 5% or less, and more desirably 3% or less. Thereby, it was confirmed that the composition distribution of each constituent element including nickel (other than oxygen) was relatively uniform in the thickness direction of the film. On the other hand, in the films obtained by the examples, the variation range of the composition ratio of lead, zirconium, titanium, and niobium was 5% or less, but the variation range of the composition ratio of nickel was 15%. It was confirmed that the composition distribution was uneven in the thickness direction.

(Example 2)
As a second example, film formation was performed for the purpose of forming a 0.91Pb (Zn _1/3 Nb _2/3 ) O ₃ -0.09PbTiO ₃ film. Table 2 shows the sputtering rate of main elements (other than lead) constituting this film.

Among these elements, zinc (Zn) has a greatly different sputtering rate. Therefore, two targets having the following composition were prepared by placing only zinc on another target.
First target: sintered body having a composition ratio of Pb: Nb: Ti = 1.2: 0.61: 0.09 Second target: ZnO sintered body

  These first and second targets were respectively placed on the target holding units 6 and 7 of the film forming apparatus shown in FIG. 1, and film formation was performed under the same film formation conditions as in the first example. As a result, the dependence of the Zn / Ti composition ratio on the power supplied to the second target was observed in the formed film. That is, it was confirmed that the zinc composition ratio in the formed film was controlled by the power supplied to the second target.

  As described above, when elements other than lead (Pb), zirconium (Zr), and titanium (Ti) are added to PZT, which is a composite perovskite compound, among the added elements, By disposing an element having a sputtering rate significantly different from that of titanium on another target, a film having a high reproducibility of the composition ratio can be formed. For example, among the elements that can be added to the composite perovskite compound, an element whose sputtering rate is significantly different from titanium (standardized value is 0.5 or less, or 1.2 or more) is shown in Table 3. The following are listed.

In addition, the sputtering rate shown in Table 3 is extracted from a vacuum handbook (Nihon Vacuum Technology Edit, published by Ohm), and shows a value for argon ions (Ar ⁺ ) having an energy of 300 eV.

  In the present embodiment described above, the target composition is determined by using the sputtering rate with respect to argon ions having an energy of 300 eV (see Tables 1 to 3). , Xenon, etc.), different energy values (for example, 300 eV to 100 keV), etc., and different sputtering rate values and standards may be used.

  In this embodiment, the PZT piezoelectric film containing lead and titanium is formed. However, the principle of the present invention, that is, the constituent elements of the film to be formed is divided into a plurality of targets based on the sputtering rate. The principle of controlling the composition of the formed film by adjusting the power supplied to each target and applying it to each target can also be applied to the case of forming a film of another material system. Accordingly, a film having a desired composition can be formed with good reproducibility by sputtering. A film formed by using such a method has a columnar structure, surface smoothness, and orientation produced by sputtering, and further, composition uniformity that can be achieved by using a plurality of targets. (Controllability).

  Here, in the film forming apparatus shown in FIG. 1, the sputtering surface of the target 21 and the sputtering surface of the target 22 are sequentially opposed to the film forming surface of the substrate 20 by rotating the substrate holder 3. . However, other configurations may be used as long as both components sputtered from the targets 21 and 22 can be attached to the substrate 20. For example, in FIG. 1, the substrate 20 may be simply moved left and right, or the targets 21 and 22 may be moved.

Alternatively, as shown in FIG. 3, the positions and orientations of the target holding portions 12 and 13 may be adjusted so that the sputtering surfaces of the two targets 23 and 24 always face the substrate 25. In this case, the substrate 25 may or may not be rotated, but it is more preferable to rotate it from the viewpoint of the uniformity of the composition of the formed film.
1 and 3, only two targets are shown, but three or more targets can be used depending on the composition of the film to be formed and the sputtering rate of the constituent elements. Is natural.

  The piezoelectric film formed by using the film forming method according to one embodiment of the present invention is applied to various devices such as a piezoelectric actuator, a pressure sensor (ultrasonic transducer), a ferroelectric memory, and a pyroelectric sensor. Can do. Since the piezoelectric film whose composition is controlled exhibits good piezoelectric performance, it is possible to improve the performance of the entire device using such a piezoelectric film.

  Next, a method for manufacturing a liquid discharge head according to an embodiment of the present invention will be described. The liquid discharge head is a component used in an ink discharge portion of an inkjet printer, and a piezoelectric film formed by using the film forming method according to an embodiment of the present invention is applied to a piezoelectric actuator for driving the liquid discharge head. Can be applied.

  FIG. 4 is a plan view showing the periphery of a printing unit of an ink jet printer to which the liquid discharge head is applied. As shown in FIG. 4, the printing unit 30 is disposed on an upper portion of the recording paper 31 that is sucked and held by a belt 34 that is stretched around rollers 32 and 33. The recording paper 31 is fed in the direction of the arrow by rollers 32 and 33 and a belt 34 driven in accordance with a control signal.

  The printing unit 30 includes a plurality of liquid ejection heads 30a to 30d that eject ink. These liquid discharge heads 30 a to 30 d are line type heads having a length corresponding to the paper width of the recording paper 31. Each of the liquid discharge heads 30a to 30d includes a plurality of nozzle portions arranged in a direction orthogonal to the paper feed direction of the recording paper 31, and black, cyan, magenta, and yellow according to the supplied control signal. Each of the inks is ejected. In addition, the print detection unit 35 includes a line sensor for imaging a print result by the print unit 30 and detects a discharge failure such as nozzle clogging based on an image read by the line sensor.

  FIG. 5 shows a part of a cross section of the liquid ejection heads 30a to 30d shown in FIG. As shown in FIG. 5, the liquid discharge head includes a nozzle plate 40, a partition wall 41 that partitions the space on the nozzle plate 40 into a plurality of regions, and a diaphragm 42 disposed on the partition wall 41. A pressure chamber 43 is defined by the nozzle plate 40, the partition wall 41, and the vibration plate 42. The pressure chamber 43 is filled with ink of a predetermined color. In addition, a plurality of liquid discharge ports (nozzle portions) 44 are formed in the surface of the nozzle plate 40 corresponding to the positions of the pressure chambers 43. Further, a lower electrode 45 is formed on the vibration plate 42, and a piezoelectric body (piezoelectric film) 46 is disposed thereon. An upper electrode 47 is formed on these piezoelectric bodies 46. A plurality of such pressure chambers are arranged in each of the liquid discharge heads 30a to 30d. In FIG. 5, a mechanism for supplying ink to each pressure chamber 43 is omitted for the sake of simplicity.

  When printing is performed, a voltage is applied to the lower electrode 45 and the upper electrode 47 in accordance with a control signal. As a result, the piezoelectric body 46 expands and contracts due to the piezoelectric effect, and the diaphragm 42 is deformed. As a result, the volume of the pressure chamber 43 changes, so that the ink filled inside is pressurized and dropped from the ejection unit 44.

  6 and 7 are views for explaining a method of manufacturing a liquid discharge head according to an embodiment of the present invention. In the normal manufacturing process, a large number of pressure chambers and the like are formed in parallel, but only one inkjet head is shown in FIGS. 6 and 7 for ease of explanation.

  First, a substrate for preparing a piezoelectric film for driving the liquid discharge head is prepared. For this purpose, a titanium film having a thickness of about 50 nm and a platinum film having a thickness of about 200 nm are formed on a silicon substrate by sputtering or the like. This platinum film is provided as a diffusion preventing layer between the piezoelectric film formed thereon and the silicon substrate. This is because lead contained in the piezoelectric film (PZT) easily reacts with silicon. The titanium film is provided to improve the adhesion between the silicon substrate and the platinum film.

Next, as shown in FIG. 6A, a PZT film 51a having a thickness of about 10 μm and a bottom surface size of about 300 μm square is formed on the substrate 50. The PZT film 51a has, for example, 0.2Pb (Ni _1/3 Nb _2/3 ) O ₃ -0.8Pb (Zr _0.5 Ti _0.5 ) O ₃ as a composition. The film formation method and film formation conditions similar to those described in Example 1 of the embodiment can be used. In order to form the above pattern, a mask provided with an opening corresponding to the arrangement of the pressure chamber 43 (FIG. 5) may be used when performing sputtering.

  Here, when a piezoelectric film such as PZT is used as an actuator as in the ink jet head, the thickness of the piezoelectric film is preferably 3 μm or more and 20 μm or less. When the thickness is 3 μm or less, the driving force by the piezoelectric film is small, so that a sufficient ink ejection force cannot be obtained. When the thickness is 20 μm or more, a sufficient displacement amount is obtained in the piezoelectric film. This is because a sufficient ink discharge amount cannot be obtained. In order to obtain a sufficient driving force and displacement amount in the piezoelectric film used as the actuator, it is more preferable that the thickness of the piezoelectric film is 5 μm or more and 20 μm or less, and more preferably 10 μm or more and 20 μm or less. desirable. Therefore, in this embodiment, the thickness of the PZT film is about 10 μm. Even with a thick film having such a thickness, it is possible to form a film with a controlled composition by using the film forming method according to one embodiment of the present invention.

  Next, as shown in FIG. 6B, a resist 51b is disposed in a region other than the PZT film 51a on the substrate 50, and a platinum electrode 52 is formed on the PZT alignment film and the resist by a sputtering method. Next, as shown in FIG. 6C, a chromium (Cr) film 53 having a thickness of about 15 μm is formed on the platinum electrode 52 by sputtering or plating. The chromium film 53 functions as a vibration plate in the liquid discharge head.

  Next, as shown in FIG. 6D, a partition wall structure 54 for defining the pressure chamber 43 (FIG. 5) is disposed on the chromium film 53. The partition wall structure 54 is a columnar structure provided with a plurality of openings 54 a having a bottom surface size of about 500 μm square, and can be manufactured by etching a material such as silicon or SUS, for example. The partition wall structure 54 is disposed so that the center of the opening 54 a corresponds to the center of the PZT film 51 a and is bonded to the chromium film 53.

  Next, as shown in FIG. 7A, the silicon substrate in the substrate 50 is removed by peeling or etching. As the etching, wet etching using a BHF (buffered hydrofluoric acid) solution may be performed, or dry etching may be performed. Of the substrate 50, the titanium film or platinum film formed on the silicon substrate may be left as it is, or may be removed by polishing or the like. Further, as shown in FIG. 7B, a platinum electrode 55 is formed on the surface from which the silicon substrate has been peeled off by sputtering, and then the resist 51b is removed.

  Next, as illustrated in FIG. 7C, the nozzle plate 56 is disposed on the partition wall structure 54. The nozzle plate 56 is a structure in which a plurality of nozzle portions 56a are formed on a plate material such as silicon or SUS, and the position of the nozzle portion 56a and the position of the pressure chamber (the opening 54a of the partition wall structure 54) correspond to each other. And bonded to the partition wall structure 54. Thereby, the liquid discharge head is completed.

  The present invention relates to a piezoelectric element used in a piezoelectric actuator for driving a liquid discharge head, an ultrasonic transducer (pressure sensor) for transmitting and receiving ultrasonic waves in an ultrasonic imaging apparatus, a pyroelectric element used in an infrared sensor, and the like. It can be used in a ferroelectric memory or the like.

It is a schematic diagram which shows the structure of the film-forming apparatus with which the film-forming method which concerns on one Embodiment of this invention is used. It is a figure which shows the dependence of the Ni / Ti composition ratio with respect to the electric power supplied to the 2nd target in the film | membrane obtained by the 1st Example. It is a schematic diagram which shows the modification of the film-forming apparatus shown in FIG. It is a top view which shows the structure of the periphery of the printing part of an inkjet printer. FIG. 5 is a diagram illustrating a part of a cross section of the liquid ejection head illustrated in FIG. 4. It is a figure for demonstrating the manufacturing method of the liquid discharge head which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the liquid discharge head which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deposition chamber 2 Exhaust pump 3 Substrate holder 4 Substrate holder drive part 5 Reactive gas supply part 6, 7, 12, 13 Target holding part 8, 9 High frequency power supply (RF)
10, 11 Matching box (MB)
20 Substrate 21-24 Target 30 Printing unit 30a-30d Liquid ejection head 31 Recording paper 32, 33 Roller 34 Belt 35 Print detection unit 40, 56 Nozzle plate 44, 56a Ejection port (nozzle unit)
41 Partition 42 Diaphragm 43 Pressure chamber 45 Lower electrode 46 Piezoelectric 47 Upper electrode 50 Substrate 51a PZT film 51b Resist 52, 55 Platinum electrode 53 Chrome film 54 Partition structure 54a Opening

Claims (11)

A film of a compound perovskite compound composed of four or more elements including lead (Pb), titanium (Ti), and oxygen (O) and formed by sputtering,
When the sputtering rate of titanium is used as a reference, the sputtering rate includes a fourth element of 0.5 or less or 1.2 or more,
The variation width of the composition distribution due to the molar ratio of the fourth element in the film is 10% or less.
A film of the composite perovskite compound.   The film of a composite perovskite compound according to claim 1, having a thickness of 3 µm or more and 20 µm or less. A method of forming a film of a composite perovskite compound composed of four or more elements including lead (Pb), titanium (Ti), and oxygen (O) by sputtering,
(A) sputtering the components contained in the first target by supplying power to the first target containing lead and titanium as constituent elements;
Included in the second target by supplying electric power to the second target containing a fourth element having a sputtering rate of 0.5 or less or 1.2 or more as a constituent element when titanium is used as a reference. A step (b) of sputtering the components;
Attaching the components sputtered from the first and second targets to a substrate heated to a predetermined temperature (c);
A film forming method comprising:   The film forming method according to claim 3, wherein the film of the composite perovskite compound has a thickness of 3 μm to 20 μm.   Steps (a) and (b) control the amounts of components sputtered from the first and second targets, respectively, by controlling the power supplied to the first and second targets. The film-forming method of Claim 3 or 4 containing.   In step (c), the first and second targets and the substrate are arranged such that the sputtering surface of the first target and the sputtering surface of the second target are sequentially opposed to the film-forming surface of the substrate. The film-forming method of any one of Claims 3-5 including moving or rotating at least one of these.   The film-forming method of any one of Claims 3-6 in which the said 2nd target contains the element which has a sputtering rate of 0.5 or less or 1.5 or more as a constituent element, when titanium is made into a reference | standard. . A pressure chamber that is defined by a vibration plate, a partition wall, and a nozzle plate provided with an ejection port, and a piezoelectric actuator that vibrates the vibration plate in order to eject the liquid in the pressure chamber from the ejection port. A method of manufacturing a liquid discharge head comprising:
When power is supplied to the first target containing lead and titanium as constituent elements, the components contained in the first target are sputtered, and when titanium is used as a reference, 0.5 or less or 1.2 (A) sputtering the components contained in the second target by supplying electric power to the second target containing the fourth element having the above sputtering rate as a constituent element;
A step (b) of forming a piezoelectric film on the substrate by attaching the components sputtered from the first and second targets to the substrate heated to a predetermined temperature;
Forming an electrode on the piezoelectric film (c);
Forming a diaphragm on the electrode (d);
Forming a partition for defining the pressure chamber on the diaphragm (e);
A step (f) of forming a nozzle plate provided with discharge ports on the partition;
A method of manufacturing a liquid discharge head comprising:   The method of manufacturing a liquid discharge head according to claim 8, wherein the step (b) includes forming a piezoelectric film having a thickness of 3 μm to 20 μm.   The method for manufacturing a liquid ejection head according to claim 8, further comprising a step of removing the substrate from the piezoelectric film by peeling or etching.   The method of manufacturing a liquid ejection head according to claim 8, further comprising a step of forming a second electrode on the piezoelectric film from which the substrate has been removed.

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