JP2001063051A - Electrostatic actuator and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reliably join a vibration plate and a silicon oxide film in an electrostatic actuator to improve the yield. SOLUTION: The vibration plate 21 is opposed to the vibration plate 21.
Has an individual electrode 12 disposed with a gap G therebetween, and applies a voltage between the diaphragm 21 and the individual electrode 12 to deform the diaphragm by electrostatic force. The individual electrode 12 is formed in the recess 10A formed in the single crystal silicon substrate 10 and on the silicon oxide film 11 formed on the silicon substrate 10.
In the vibration plate 21 and the silicon oxide film 11, at least a region 15 containing an impurity having a concentration equal to or higher than the impurity concentration of the silicon substrate 10 is formed in a convex region 10B of the silicon substrate.
The silicon oxide film 11 formed on the convex region 10B
And the diaphragm 21 are joined to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic actuator and a method for manufacturing the same, and more particularly, to a type in which a diaphragm in an on-demand type ink jet printer head, micropump, or the like is driven by electrostatic attraction. The present invention relates to an electrostatic actuator, its micromachining technology, and micromachining technology.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 6-71882 discloses an electrostatic ink jet head for driving a diaphragm used in an on-demand type ink jet printer by electrostatic attraction. Among them, there is disclosed an example of an electrostatic inkjet head in which individual electrodes that are insulated and separated from each other are formed in a gap spacer of a silicon oxide film so as to face a diaphragm.

In the structure of the ink jet head disclosed in Japanese Patent Application Laid-Open No. 6-71882, a silicon oxide film is formed on a silicon substrate, and a gap is formed by etching the silicon oxide film halfway. Although the individual electrodes facing the diaphragm are arranged inside the gap, the gap between the diaphragm and the electrodes is formed by etching in this inkjet head, so the gap depth that affects the operation characteristics of the inkjet head is The uniformity was poor, and the characteristics varied.

[0004]

SUMMARY OF THE INVENTION In order to suppress the above-mentioned variation, the present applicant has first formed an individual electrode in a concave portion of a single-crystal silicon substrate and formed an individual electrode in the silicon substrate sequentially. An ink jet head formed on a silicon film and a method of manufacturing the same have been proposed (Japanese Patent Application No. Hei.
0-349213). In the electrostatic actuator proposed earlier by the present applicant, the impurity concentration of the convex region of the silicon substrate is equal to the impurity concentration of the substrate, and the silicon oxide film formed on the convex region and the diaphragm are bonded to each other. Is what is being done. However, in the case of such a configuration, although the variation in the gap can be suppressed remarkably, a problem arises in that the bonding property between the diaphragm and the silicon oxide film is problematic and the yield is reduced.

[0005]

According to a first aspect of the present invention, there is provided a semiconductor device comprising: a diaphragm; and an individual electrode disposed opposite to the diaphragm and disposed with a gap therebetween. An electrostatic actuator that applies a voltage between the diaphragm and the individual electrode and deforms the diaphragm by electrostatic force, wherein the individual electrode is in a recess formed in a single-crystal silicon substrate. And, in the electrostatic actuator formed on the silicon oxide film formed on the silicon substrate, a region containing an impurity at least the impurity concentration of the silicon substrate is formed in a convex region of the silicon substrate, The silicon oxide film and the vibration plate formed on the convex region are joined to each other.

According to a second aspect of the present invention, in the first aspect of the present invention, the width of the region formed in the convex region of the silicon substrate and containing at least the impurity concentration higher than the impurity concentration of the silicon substrate is larger than the width of the convex region. It is characterized by being narrow.

According to a third aspect of the present invention, in the first or second aspect, the impurity atoms contained in the convex region of the silicon substrate are boron.

According to a fourth aspect of the present invention, in the first or second aspect, an impurity atom contained in the convex region of the silicon substrate is phosphorus.

According to a fifth aspect of the present invention, in the method of manufacturing an electrostatic actuator according to claim 3, wherein the impurity atom contained in the convex region of the silicon substrate is phosphorus. The temperature of forming the silicon oxide film formed thereon is 1000 ° C. or less.

According to a sixth aspect of the present invention, in the method of manufacturing an electrostatic actuator of claim 4, wherein the impurity atom contained in the convex region of the silicon substrate is phosphorus. The formation temperature of the silicon oxide film sequentially formed thereon is 1000 ° C. to 1
The temperature is 200 ° C.

[0011]

1 and 2 are views for explaining the structure and operation of an electrostatic actuator according to the present invention. FIG. 1 is a top view of the electrostatic actuator according to the present invention. 2 (A) to 2 (C) show an AA section, a BB section, and a CC section of FIG. 1, respectively. The electrostatic actuator of the present invention basically includes a silicon diaphragm having conductivity, an individual electrode provided with a predetermined gap with respect to the diaphragm, and an electrode provided with the individual electrode. And a substrate.

1 and 2, reference numeral 10 denotes an n-type or
It is a single crystal silicon substrate including p-type impurity atoms. Normally, a single-crystal silicon substrate with a plane orientation (100) is used, but depending on the process, a plane orientation (110) or (11) is used.
There is no problem even if the single crystal silicon substrate of 1) is used.
Reference numeral 12 denotes individual electrodes formed on the silicon oxide film 11 sequentially formed on the single-crystal silicon substrate 10 and insulated and separated from each other, and includes various impurities such as an ion implantation method, a coating diffusion method, and a solid diffusion method. N-type or p-type polycrystalline silicon desirably containing 1E18 / cm ³ or more of impurity atoms formed by the introduction method, or a high melting point metal such as titanium nitride formed by a reactive sputtering method.

The individual electrode 12 is formed in the recess 10A of the silicon substrate 10 and on the silicon oxide film 11. 13 is a diaphragm 21 and the individual electrodes 12
Is an insulator such as a silicon nitride film and a silicon oxide film for ensuring insulation of the semiconductor device. Reference numeral 11 denotes a silicon oxide film formed by a thermal oxidation method or the like.
This is a gap spacer for insulating the substrate and the silicon substrate 10 and further forming a gap (gap) G between the diaphragm 21 and the individual electrode 12. By applying a voltage to the individual electrode 12 facing the silicon thin film diaphragm 21 via the gap spacer 11, an electrostatic attraction is generated.

Reference numeral 14 denotes a pad section for applying a drive voltage to the individual electrodes 12 so as to make the individual electrodes 12 conductive, and a pad for applying a voltage to the individual electrodes from the outside and for performing mounting such as FPC and wire bonding. It is a take-out part. 1
Reference numeral 5 denotes a region formed in the convex region 10B of the silicon substrate 10 and containing impurities such as P and B at least at the impurity concentration of the silicon substrate, and the silicon oxide film 11 formed on the convex region 10B containing the impurity. And diaphragm 21 are shown in FIG.
They are joined to each other in the region (C).

FIG. 3 is a diagram showing details of the region shown in FIG. 2 (C). The same effect can be obtained in either of the configurations shown in FIGS. 3 (A) and 3 (B). 3A, the width W1 of the region 15 containing impurities such as P and B at least over the impurity concentration of the substrate 10 formed on the protrusion 10B of the silicon substrate 10 and the protrusion 10B of the silicon substrate will be described. Are formed so that the widths W2 of them are equal. At this time, the thickness of the silicon oxide film 11 formed in the concave portion 10A and the convex portion 10B of the silicon substrate 10 is the concave portion 10A (Tox1).
And the convex portion 10B (Tox2), respectively, and Tox1 <T
ox2. In this case, the vibration plate 21 is joined in the region of the silicon oxide film of the convex portion 10B having a larger silicon oxide film thickness than the concave portion 10A of the silicon substrate.

FIG. 3B is a diagram showing another configuration of the portion shown in FIG. 2C. In this configuration, the silicon substrate 10
The width W1 of the region 15 containing impurities such as P and B at least equal to or higher than the impurity concentration of the substrate 10 and the width W2 of the projection 10B of the silicon substrate
It is formed so that 1 <W2. At this time, the thickness of the silicon oxide film 11 formed in the concave portion 10A and the convex portion 10B of the silicon substrate 10 is different between the concave portion (Tox1) and the convex portion (Tox2), and becomes Tox1 <Tox2. In this case, the diaphragm 2 is formed in the region of the silicon oxide film 11 of the convex portion 10B in which the silicon oxide 11 is thicker than the concave portion 10A of the silicon substrate.
1 is joined.

As described above, the protrusion 1 of the silicon substrate 10
0B, the width W1 of the region 15 containing impurities such as P and B at least above the impurity concentration of the silicon substrate 10 and the width W2 of the convex portion 10B of the silicon substrate 10 are at least W1 <W2. When the thickness of the silicon oxide film 11 formed in the concave portion 10A and the convex portion 10B of the silicon substrate 10 satisfies the concave portion (Tox1) <the convex portion (Tox2), the reason why the diaphragm 21 improves the bonding property in the convex portion region is as follows. To
FIG. 4 is an enlarged view corresponding to the part of FIG.
This will be described with reference to FIG.

FIG. 4A is a diagram showing a conventional configuration of the portion shown in FIG. 2C. In this conventional configuration, the silicon substrate 1 is formed.
No impurity is particularly introduced into the 0 convex portion. In this case, the thickness of the silicon oxide film 11 sequentially formed on the silicon substrate 10 is such that the silicon oxide film thickness Tox1 formed in the concave portion 10A of the silicon substrate 10 and the silicon oxide film Tox2 formed in the convex portion 10B are different. Become equal (Tox1 = To
x2). At the same time, since the oxidation rate of the silicon substrate 10 is different between the surface of the convex portion and the side wall surface of the concave portion of the silicon substrate 10, the thickness of the silicon oxide film at the boundary Q point becomes particularly large. In the case of such a configuration, the connection with the diaphragm 21 is performed only at the point Q, and the strength of the connection is extremely small, causing a decrease in yield and reliability.

FIG. 4B is a diagram showing the configuration of the present invention.
In the configuration of the present invention, at least the width W1 of the protrusion 10B of the silicon substrate 10 is equal to or smaller than the width W2 of the protrusion 10B, that is, W1 = W2 or W1 <W2. When a region 15 containing impurities such as P and B is formed at a concentration higher than the impurity concentration of the silicon substrate 10 and the silicon oxide film 11 is formed on the silicon substrate 10 by thermal oxidation, the region 15 to which the impurity is introduced is formed.
In this case, accelerated oxidation occurs, and the silicon oxide film thickness Tox2 formed on the convex portion 10B of the silicon substrate 10 becomes thicker than the silicon oxide film thickness Tox1 formed on the concave portion 10A (T
ox1 <Tox2).

At this time, as in the conventional structure, the oxidation rate at the boundary between the concave portion 10A and the convex portion 10B of the silicon substrate 10 is different between the surface of the convex portion and the side wall surface of the concave portion. Although the thickness is increased, the thickness of the silicon oxide in the region 15 containing the impurity becomes larger than the increase in the thickness due to the effect of the accelerated oxidation. Therefore, in the case of the structure of the present invention, the bonding with the vibration plate 21 becomes the entire surface of the accelerated oxidized silicon oxide film on the region 15 containing the impurity, and the bonding strength is remarkably improved. As a result, yield and reliability are improved.

Next, with reference to FIG. 5, a flow of manufacturing the ink jet head of the present invention will be described. In FIG. 5, the figure on the left is a cross section taken along the line AA in FIG. 1, and the figure on the right is
The LL sectional view of the figure on the left side of FIG. 5 is shown, respectively. First, the plane orientation (100) or (111), (110), p
A silicon oxide film 41 is formed on a type or n-type single crystal silicon substrate 40 by a thermal oxidation method (FIG. 5A). Next, a silicon nitride film 42 is formed by an LPCVD method, a thermal CVD method, or the like. At this time, the thickness of the silicon nitride film 42 is set to be equal to or greater than the thickness acting as a diffusion barrier of oxygen in the subsequent thermal oxidation step (FIG. 5B).

The silicon nitride film 42 is patterned by ordinary photolithographic etching, and pyro-oxidation is performed. At this time, since the silicon nitride film 42 functions as a barrier for oxygen diffusion, the silicon oxide film 43 grows thick only in a region where the silicon nitride film 42 does not exist (FIG. 5).
(C)). With such a configuration, impurity atoms such as P and B are implanted into the entire surface at least at a concentration higher than that of the substrate. Or,
After removing the silicon nitride film 42, impurity atoms such as P and B may be implanted over the entire surface at least at the concentration of the substrate. Alternatively, an impurity is implanted only into a region smaller than the width of the convex portion of the silicon substrate by using a resist mask, and a region 44 containing an impurity having a width equal to or smaller than the width of the convex portion of the silicon substrate is formed. May be. In the example of FIG. 5, an example is shown in which impurities are implanted over the entire surface without removing the silicon nitride film 42 used as the oxygen diffusion mask (FIG. 5D).

Next, the entire surface of the silicon nitride film 42 and the silicon oxide film 43 is removed by etching. At this time, the single crystal silicon substrate 4 is formed by the formed silicon oxide film 43.
A recess is formed at 0. By controlling the thickness of the silicon oxide film 43 formed on the silicon substrate 40, the depth of the concave portion formed on the silicon substrate 40 is controlled, and the gap length between the individual electrode and the diaphragm is controlled. A silicon oxide film 45 is formed on the entire surface of the single crystal silicon substrate on which such concave portions are formed by a pyro-oxidation method. At this time, the pyro oxidation is desirably performed at a temperature at which the accelerated oxidation is remarkable. That is, when the B impurity is introduced into the region 44, 1000
C. or less, preferably 1000 ° C. when P impurities are introduced.
It is desirable to carry out at -1200 ° C. In the silicon oxide film 45 formed on the silicon substrate 40, the oxide film thickness of the region 44 in the convex region of the silicon substrate 40 that contains impurities at least at the substrate concentration or higher is larger than the silicon oxide film thickness of the silicon concave portion (FIG. E)).

Next, in the recesses, patterned and insulated and isolated impurity atoms are preferably 1E18.
/ Cm ³ or more high melting point metal such as n-type or p-type polycrystalline silicon or titanium nitride (individual electrode) 46 and an insulating film 47 such as a silicon oxide film or a silicon nitride film are formed on the concave portion of the silicon substrate 40. It is formed on the silicon oxide film 45 (FIG. 5F). A diaphragm 21 having conductivity such as silicon is directly bonded or eutectic bonded to such an electrode substrate (FIG. 5 (G)) to complete the electrostatic actuator of the present invention. In FIG. 5G, reference numbers used in the description of FIG. 2 are added in parentheses in order to clarify the relationship with the actuator shown in FIG.

Next, with reference to FIG. 6, a flow of manufacturing an ink jet head will be described as an application of the electrostatic actuator of the present invention. In FIG. 6, the diagram on the left shows the AA cross section of FIG. 1, and the diagram on the right shows the LL cross section of the left diagram of FIG. First, plane orientation (100) or (111), (110), p-type or n
A silicon oxide film 41 is formed on a single-crystal silicon substrate 40 by a thermal oxidation method (FIG. 6A). Next, LPC
The silicon nitride film 42 is formed by a VD method, a thermal CVD method, or the like. At this time, the thickness of the silicon nitride film is set to be equal to or greater than the thickness acting as a diffusion barrier of oxygen in a subsequent thermal oxidation step (FIG. 6B).

The silicon nitride film 42 is patterned by ordinary photolithographic etching, and pyro-oxidation is performed. At this time, since the silicon nitride film acts as a barrier for oxygen diffusion, the silicon oxide film 43 grows thick only in a region where the silicon nitride film does not exist (FIG. 6).
(C)). With such a configuration, impurity atoms such as P and B are implanted into the entire surface at least at a concentration higher than that of the substrate. Or,
After removing the silicon nitride film 42, impurity atoms such as P and B may be implanted over the entire surface at least at the concentration of the substrate. Alternatively, an impurity is implanted only into a region smaller than the width of the convex portion of the silicon substrate by using a resist mask, and a region 44 containing an impurity having a width equal to or smaller than the width of the convex portion of the silicon substrate is formed. May be. FIG. 6 shows an example in which impurities are implanted over the entire surface without removing the silicon nitride film 42 used as the oxygen diffusion mask (FIG. 6D).

Next, the entire surface of the silicon nitride film 42 and the silicon oxide film 43 is removed by etching. At this time, the single crystal silicon substrate 4 is formed by the formed silicon oxide film 43.
A recess is formed at 0. By controlling the thickness of the silicon oxide film formed on the silicon substrate, the depth of the concave portion formed on the silicon substrate is controlled, and the gap length between the individual electrode and the diaphragm is controlled. A silicon oxide film 45 is formed on the entire surface of the single crystal silicon substrate on which such concave portions are formed by a pyro-oxidation method. At this time, the pyro oxidation is desirably performed at a temperature at which the accelerated oxidation is remarkable. That is, when the B impurity is introduced into the region 44, the temperature is preferably 1000 ° C. or lower, and when the P impurity is introduced, the temperature is preferably 1000 ° C. to 1200 ° C. In the silicon oxide film 45 formed on the silicon substrate 40, the oxide film thickness of the region 44 in the convex region of the silicon substrate, which contains impurities at least at the substrate concentration or higher, is larger than the silicon oxide film thickness of the silicon concave portion (FIG. 6).
(E)).

Next, in the recesses, patterned and insulated and separated impurity atoms, preferably 1E18
/ Cm ³ or more of n-type or p-type polycrystalline silicon or a refractory metal such as titanium nitride 46 and an insulating film 47 such as a silicon oxide film or a silicon nitride film formed on a concave portion of a silicon substrate. It is formed on the silicon film 45 (FIG. 6F). Thus, the electrode substrate is completed.

Next, the conductivity type is p-type or n-type, and the plane orientation (1
10) a diffusion region 21 formed by diffusing an impurity having a p-type or n-type conductivity of 1E19 / cm ³ or more to one surface of the single-crystal silicon substrate 20 to a depth equal to the thickness of the diaphragm;
Further, an ink liquid chamber substrate having a single crystal silicon etching mask pattern 22 such as a silicon oxide film, a silicon nitride film, or tantalum pentoxide, which defines an ink liquid chamber and an ink nozzle, is formed on the surface opposite to the diffusion region. Align with the electrode substrate shown in FIG. At this time, a single-crystal thin-film silicon film having a thickness equal to the thickness of the diaphragm is formed on the (110) single-crystal silicon substrate with a silicon oxide film interposed therebetween: an SOI (Silicon on Insulator) substrate and an electrode substrate are joined. May be. The electrode substrate and the ink liquid chamber substrate are bonded by a direct bonding method, an anodic bonding method, or the like (FIG. 6).
(G)).

Next, as shown in FIG. 6 (G), the substrate in which the electrode substrate and the ink liquid chamber substrate are joined is placed on the side where the single crystal silicon etching mask pattern 22 is formed.
Anisotropic etching is performed by H, TMAH or the like. At this time, etching is spontaneously stopped in the diffusion region 21 containing impurities at a high concentration, and a diaphragm (diffusion region) 21 corresponding to the diffusion depth is formed. When the SOI substrate is anisotropically etched, the etching stops on the silicon oxide film. Note that there is no problem even if the silicon oxide film is removed (FIG. 6H). An ink liquid chamber cover 3 made of a glass plate or a metal plate in which an ink supply flow path 31 is formed by sandblasting or laser processing on the upper surface of the bonded substrate.
Paste 0. The silicon diaphragm 21 and the insulating film 47 are removed by etching only in the pad region to form the pad portion 46A, thereby completing the ink jet head of the present invention (FIG. 6).
(I)). In FIG. 6 (I), reference numbers corresponding to FIG. 2 are added in parentheses.

At this point, the ink liquid chamber side is an individual liquid chamber 24 corresponding to each nozzle 23 formed by anisotropic etching and a common liquid chamber 25 for supplying ink thereto.
Are formed, and both flow paths 2 are formed by anisotropic etching.
The structure communicates with 6. When a voltage is applied to the individual electrode pads 46A (12A) of the inkjet head, the single crystal silicon diaphragm 21 and the individual electrodes 46 (12)
During this time, the electrostatic force acts, the diaphragm 21 bends toward the individual electrode 12, the individual liquid chamber 24 becomes negative pressure, and the ink flows from the common liquid chamber 25 to the individual liquid chamber 24 through the flow path 26 for ink supply. Supplied. When the voltage is cut off, single crystal silicon diaphragm 2
1 returns to its original position due to the rigidity of the silicon. At this time, the individual liquid chamber 24 is pressurized, ink is ejected in the direction of the arrow via the nozzle 23, and lands on the recording paper.

Although FIG. 6 shows an example in which the direction of ink ejection is horizontal to the substrate, ink can be ejected vertically to the substrate by changing the direction of the ink nozzles. . Also, in the present ink jet head manufacturing flow, an example is shown in which the vibration plate, the ink liquid chamber, and the nozzle portion are formed by joining the single crystal silicon substrate and the electrode substrate that form the vibration plate and the ink liquid chamber and then performing anisotropic etching. However, the nozzle portion may be formed after the single crystal silicon substrate on which the ink liquid chamber and the vibration plate are formed by anisotropic etching and the electrode substrate are joined.

(Embodiment 1) FIG. 7 is a sectional view for explaining an embodiment of an ink jet head using an electrostatic actuator according to the present invention. FIG. FIG. 7B is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 7B is a cross-sectional view taken along the line BB of FIG.
(C) shows the CC cross section of FIG. The ink jet head of this example was manufactured according to the flow shown in FIG. In FIG. 7, reference numeral 10 denotes an n-type single-crystal silicon substrate having a plane orientation (100) resistance of 10 to 20 Ω-cm. An individual electrode 12 is arranged on the silicon oxide film 11 in the recess formed on the silicon substrate 10.

Reference numeral 11 denotes a silicon oxide film having a thickness of 400 nm and a thickness of 380 nm of a concave portion of the silicon substrate formed at an oxidation temperature of 900 ° C. in a pyro-oxidizing furnace in an atmosphere of H ₂ gas and O ₂ . The depth of the recess formed in single crystal silicon substrate 10 is 800 nm. Reference numeral 15 denotes a concentration of 1E18 / c of the B impurity formed in the convex region of the silicon substrate.
A m ³ including regions are narrower than the width of the convex area. Reference numeral 12 denotes an individual electrode of titanium nitride (TiN) having a thickness of 150 nm formed by a sputtering method. A 200 nm thick silicon oxide film 13 was formed on the individual electrode 12 by a plasma CVD method. This silicon oxide film 1
Reference numeral 3 is for securing insulation between the diaphragm 21 and the individual electrodes 12.

Reference numeral 12A denotes an area where the silicon oxide film 13 is removed by etching, which is an electrode pad area for applying a drive voltage to the individual electrode 12 of the ink jet head. Vibration plate 21 having a thickness of 3 μm and containing boron impurity atoms of 1E20 / cm ³ or more formed by anisotropically etching single crystal silicon substrate 20 having a plane orientation of (110) with KOH.
Are arranged via the silicon oxide film 15. An ink liquid chamber 24 formed by anisotropic etching of KOH and a common liquid chamber 25 for supplying ink thereto are formed in the (110) plane orientation single crystal silicon substrate 20.
Is communicated by Further, a glass plate 30 on which an ink supply channel 31 and an ink nozzle 32 are formed by sandblasting is stuck on the ink liquid chamber.

In the above-described ink jet head, the diaphragm 21 was electrically grounded, a positive drive voltage was applied to the individual electrode 12 via the electrode pad 12A, and the individual electrodes 12 were driven at a constant frequency. When a voltage was applied, an electrostatic attraction was applied between the diaphragm 21 and the individual electrodes 12, and the diaphragm 21 was pulled in the direction of the individual electrodes 12. At this time, the pressure of the ink liquid chamber 24 became negative, and ink was supplied from the common liquid chamber 25 to the individual liquid chamber 24 via the flow path 26 for supplying ink. The diaphragm 21 returns to its original position due to the rigidity of the silicon in accordance with the frequency of the drive voltage. At this time, the individual liquid chamber 24 is pressurized, ink is ejected in the direction of the arrow via the nozzle 32, and lands on the recording paper. And recorded.

(Embodiment 2) FIG. 8 is a view for explaining another embodiment of an ink jet head using an electrostatic actuator according to the present invention. FIG. FIG. 8B shows a cross section taken along the line AA in FIG.
FIG. 8C is a cross-sectional view taken along the line BB of FIG.
Shows the CC cross section of FIG. The ink jet head of this example was manufactured according to the flow shown in FIG. 10 is plane orientation (100) resistivity 10-20Ω-c
m p-type single crystal silicon substrate. An individual electrode 12 is arranged on the silicon oxide film 11 in the concave portion formed on the silicon substrate 10.

Reference numeral 11 denotes a 500 nm thick convex portion of the silicon substrate and a 480 thick concave portion of the silicon substrate formed in a pyro-oxidizing furnace in an atmosphere of H ₂ gas and O ₂ gas at an oxidation temperature of 1050 ° C.
nm silicon oxide film. Single crystal silicon substrate 10
Has a depth of 500 nm. Reference numeral 15 denotes a P impurity formed at a convex region of the silicon substrate and having a concentration of 1E1.
It is a region containing 8 / cm ³ and has a width equal to the width of the convex region. 12 is a thickness 1 formed by a sputtering method.
50 nm titanium nitride (TiN) individual electrode. The thickness 1 formed on the individual electrode 12 by the plasma CVD method.
A 50 nm silicon oxide film 13 was formed. The silicon oxide film 13 is for ensuring insulation between the diaphragm 21 and the individual electrodes 12.

Reference numeral 12A denotes an area where the silicon oxide film 13 is removed by etching, which is an electrode pad area for applying a drive voltage to the individual electrode 12 of the ink jet head. Using an SOI (Silicon on Insulator) substrate, a single crystal silicon substrate 20 having a plane orientation of (110) is formed to a thickness of 30
A single-crystal silicon vibration plate 27a having a thickness of 3 μm and formed by anisotropic etching using KOH up to the silicon oxide film 27b of 0 nm is arranged via the silicon oxide film 27b. An ink liquid chamber 2 formed by anisotropic etching of KOH is
4 and a common liquid chamber 25 for supplying ink thereto are formed, and both are communicated by a flow path 26. Further, a glass plate 30 on which an ink supply channel 31 and an ink nozzle 32 are formed by sandblasting is stuck on the ink liquid chamber.

In the above-described ink jet head, the diaphragm 21 (27a, 27b) is electrically grounded,
A positive drive voltage was applied to the individual electrode 12 via the electrode pad 12A, and the individual electrode 12 was driven at a constant frequency. When a voltage was applied, an electrostatic attraction was exerted between the diaphragm 21 and the individual electrode 12, and the diaphragm 21 was pulled in the direction of the individual electrode 12. At this time, the ink liquid chamber 24 has a negative pressure, and the flow path 2 for supplying ink is
The ink was supplied from the common liquid chamber 25 to the individual liquid chambers 24 through 6. The diaphragm 21 returns to its original position due to the rigidity of the silicon with respect to the frequency of the drive voltage. At this time, the individual liquid chamber 24 is pressurized, and the ink is ejected in the direction of the arrow via the nozzle 23 to land on the recording paper. And recorded.

(Embodiment 3) FIG. 9 is a view for explaining still another embodiment of an ink jet head using an electrostatic actuator according to the present invention. FIG. 9 (A) shows the individual electrode portion of FIG. 9B shows a cross section taken along line AA of FIG. 9, and FIG. 9B shows a cross section taken along line BB of FIG.
(C) shows the CC cross section of FIG. The ink jet head of this example was manufactured according to the flow shown in FIG. 10 is plane orientation (100) resistivity 10-20Ω
It is an n-type single crystal silicon substrate of −cm. An individual electrode 12 is arranged on the silicon oxide film 11 in the recess formed on the silicon substrate 10.

Reference numeral 11 denotes a silicon substrate formed by a pyro-oxidation furnace in an atmosphere of H ₂ gas and O ₂ gas at an oxidation temperature of 1000 ° C., the thickness of the convex portion of the silicon substrate being 300 nm, and the thickness of the concave portion of the silicon substrate being 280.
nm silicon oxide film. Single crystal silicon substrate 10
Is 400 nm. Reference numeral 15 denotes a P impurity formed at a convex region of the silicon substrate and having a concentration of 1E1.
It is a region containing 9 / cm ³ and has a width smaller than the width of the convex region. Reference numeral 12 denotes a 200-nm-thick polycrystalline silicon individual electrode containing a P impurity of 5E19 / cm ³ . A thickness of 10 formed on this individual electrode 12 by a thermal oxidation method
A 0 nm silicon oxide film 13 was formed.

The silicon oxide film 13 is for ensuring insulation between the diaphragm 21 and the individual electrodes 12. 12A
Is an area where the silicon oxide film 13 is removed by etching, and is an electrode pad area for applying a drive voltage to the individual electrode 12 of the ink jet head. SOI (Si
A 3 μm-thick single-crystal silicon vibrating plate in which a single-crystal silicon substrate 20 with a plane orientation of (110) is formed on a 300 nm-thick silicon oxide film 28 b by anisotropic etching using KOH using a licon on insulator substrate. 28a are arranged via the silicon oxide film 28b. Plane orientation (1
10) An ink liquid chamber 24 formed by anisotropic etching of KOH and a common liquid chamber 25 for supplying ink to the single crystal silicon substrate 20 are formed in the single crystal silicon substrate 20, and both are communicated by a flow path 26. Further, a glass plate 30 on which ink supply channels 31 and ink nozzles are formed by sandblasting is adhered on the ink liquid chamber.

In the above-described ink jet head, the diaphragm 21 was electrically grounded, a positive drive voltage was applied to the individual electrode 12 via the electrode pad 12A, and the individual electrodes 12 were driven at a constant frequency. When a voltage was applied, an electrostatic attraction was exerted between the diaphragm 21 and the individual electrode 12, and the diaphragm 21 was pulled in the direction of the individual electrode 12. At this time, the ink liquid chamber 24 has a negative pressure, and passes through a flow path 26 for supplying ink to the common liquid chamber 25.
To the individual liquid chamber 24. The diaphragm 21 returns to its original position due to the rigidity of the silicon in accordance with the frequency of the drive voltage. At this time, the individual liquid chamber 24 is pressurized, ink is ejected in the direction of the arrow via the nozzle 23, and lands on the recording paper. And recorded.

[0045]

(Effect corresponding to the first aspect of the invention) In the electrostatic actuator according to the first aspect, at least a region containing an impurity having a concentration higher than the impurity concentration of the silicon substrate is formed in the convex region of the silicon substrate. Therefore, the silicon oxide film formed on the region having a high impurity concentration is accelerated and oxidized, so that the surface becomes a flat surface, and the bonding property with the diaphragm is improved.

(Effect corresponding to the second aspect of the present invention) In the electrostatic actuator according to the first aspect, the width of the region containing the impurity at least equal to or higher than the impurity concentration of the silicon substrate formed in the convex region of the silicon substrate is convex. Since the width is smaller than the width of the region, the region to be accelerated oxidized is narrowed, the influence of oxidation from the surroundings is reduced, and the bondability with the diaphragm is further improved.

(Effect corresponding to the third aspect of the invention) In the electrostatic actuator according to the first or second aspect, since the impurity atoms contained in the convex region of the silicon substrate are boron, an increase in the formation of the silicon oxide film is increased. Rapid oxidation easily occurs,
Not only is the bonding property with the diaphragm improved, but also the manufacturing cost is reduced because it can be formed by a conventional silicon semiconductor electronic device forming process.

(Effect Corresponding to the Invention of Claim 4) In the electrostatic actuator according to claim 3, the formation temperature of the silicon oxide film sequentially formed on the silicon substrate is 100.
Since the temperature is 0 ° C. or less, efficient accelerated oxidation can be performed.

(Effect corresponding to the fifth aspect of the invention) In the electrostatic actuator according to the first or second aspect, since the impurity atoms contained in the convex region of the silicon substrate are phosphorus, an increase in the time of forming the silicon oxide film is achieved. Rapid oxidation easily occurs,
Not only is the bonding property with the diaphragm improved, but also the manufacturing cost is reduced because it can be formed by a conventional silicon semiconductor electronic device forming process.

(Effect corresponding to the invention of claim 6) In the electrostatic actuator according to claim 5, the formation temperature of the silicon oxide film sequentially formed on the silicon substrate is 100.
Since the temperature is 0 ° C to 1100 ° C, efficient accelerated oxidation can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the configuration and operation of an electrostatic actuator according to the present invention.

FIG. 2 is a diagram for explaining the configuration and operation of the electrostatic actuator according to the present invention.

FIG. 3 is a diagram showing details of an area shown in FIG. 2 (C).

FIG. 4A is a diagram showing a conventional configuration of a part shown in FIG. 2C, and FIG. 4B is a diagram showing a configuration of the present invention.

FIG. 5 is an explanatory diagram illustrating a production flow of the inkjet head of the present invention.

FIG. 6 is an explanatory diagram of a production flow when the electrostatic actuator of the present invention is applied to an inkjet head.

FIG. 7 is a cross-sectional view illustrating an embodiment of an ink jet using an electrostatic actuator according to the present invention.

FIG. 8 is a view for explaining another embodiment of the ink jet head using the electrostatic actuator according to the present invention.

FIG. 9 is a view for explaining still another embodiment of the ink jet head using the electrostatic actuator according to the present invention.

[Description of Signs] 10, 20, 40: Single-crystal silicon substrate, 10A: Silicon substrate concave portion, 10B: Silicon substrate convex portion, 11, 4
1, 43, 45: silicon oxide film (gap spacer), 12: individual electrode, 12A: electrode pad, 13: insulator (silicon oxide film), 14: pad portion, 15, 44
... High impurity concentration region, 21 ... Vibration plate, 22 ... Single crystal silicon etching mask pattern, 23 ... Nozzle, 24 ...
Individual liquid chamber (ink liquid chamber), 25 common liquid chamber, 26 flow path, 30 ink liquid chamber cover (glass plate), 31 ink supply flow path, 32 ink nozzle, 42 silicon nitride film, 46: titanium nitride (individual electrode), 46A: pad portion, 47: insulating film.

Claims (6)

[Claims] 1. A diaphragm, comprising: a diaphragm; and an individual electrode disposed opposite to the diaphragm with a gap therebetween. A voltage is applied between the diaphragm and the individual electrode. And an electrostatic actuator that deforms the vibration plate by electrostatic force, wherein the individual electrode is formed in a recess formed in a single crystal silicon substrate, and formed on the silicon substrate. In an electrostatic actuator formed on a silicon oxide film, at least a region of the silicon substrate containing an impurity having an impurity concentration or higher is formed in a convex region of the silicon substrate, and the silicon oxide formed on the convex region An electrostatic actuator, wherein the membrane and the diaphragm are joined to each other. 2. The electrostatic actuator according to claim 1, wherein a width of a region formed in the convex region of the silicon substrate and containing at least the impurity concentration higher than the impurity concentration of the silicon substrate is smaller than a width of the convex region. An electrostatic actuator, characterized in that: 3. The electrostatic actuator according to claim 1, wherein the impurity atoms contained in the convex region of the silicon substrate are boron. 4. The electrostatic actuator according to claim 1, wherein the impurity atom contained in the convex region of the silicon substrate is phosphorus. 5. The method of manufacturing an electrostatic actuator according to claim 3, wherein the impurity atoms contained in the convex region of the silicon substrate are phosphorus. A method for manufacturing an electrostatic actuator, wherein the formation temperature of the silicon oxide film is 1000 ° C. or less. 6. The method of manufacturing an electrostatic actuator according to claim 4, wherein the impurity atoms contained in the convex region of the silicon substrate are phosphorus. Forming a silicon oxide film at a temperature of 1000 ° C. to 1200 ° C.