JP2010179514A - Electrostatic actuator, liquid droplet ejection head, method for manufacturing those, and liquid droplet ejection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic actuator that is excellent in driving durability, can be driven by a high voltage, can be densified, and is excellent in process compatibility, and to provide a method for manufacturing the same. <P>SOLUTION: The electrostatic actuator 4 includes discrete electrodes 5 formed on an electrode substrate 3 and a diaphragm 6 arranged so as to be opposed to the discrete electrodes 5 with a predetermined gap therebetween. The counter face of each of the discrete electrodes 5 is formed to have a multi-stepwise structure. Surface protection films 8a, 8b having different solid-state properties are formed respectively at the uppermost step and the lowermost step of the counter face of each of the discrete electrodes 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrostatic actuator, a droplet discharge head, a manufacturing method thereof, and a droplet discharge device used for an electrostatic drive type inkjet head or the like.

Some droplet discharge heads that discharge droplets from nozzle holes use an electrostatic force as a driving method of an actuator. Hereinafter, an actuator based on this driving method is referred to as an “electrostatic actuator”.
For example, an electrostatic actuator of an inkjet head, which is a typical example of a droplet discharge head, generally has an individual electrode (fixed electrode) formed on a substrate such as glass and a predetermined gap (gap) between the individual electrodes. And a diaphragm made of silicon (movable electrode) disposed opposite to each other, and driving means for generating an electrostatic force between the diaphragm and the individual electrode to cause displacement of the diaphragm. Then, by oscillating the vibration plate of the discharge chamber formed in the ink flow path with electrostatic force, ink droplets are ejected and landed on the recording paper from the nozzle holes to perform printing or the like.

In such an electrostatic drive type ink jet head, the nozzle density is increased and the displacement of the diaphragm is increased without increasing the drive voltage, thereby increasing the droplet ejection energy. Has been studied. As one of such structures, there is a system in which a plurality of steps are provided on individual electrodes in a stepped manner, and the individual electrodes are configured in multiple stages (for example, see Patent Documents 1 to 3).
In Patent Document 1, stepped steps are formed on an oxide film or glass substrate on a silicon substrate on which individual electrodes are formed, and individual electrodes are formed in multiple stages thereon.
In Patent Document 2, a stepped step is formed on a glass substrate on which individual electrodes are formed, and individual electrodes are formed in multiple stages thereon.
In patent document 3, an individual electrode is formed in multiple steps by laminating | stacking electrode material on the glass substrate in which an individual electrode is formed in step shape.

In the electrostatic actuators disclosed in the above Patent Documents 1 to 3, when an electrostatic attractive force acts between the individual electrode and the diaphragm, the diaphragm has an interval between the individual electrode and the diaphragm (also referred to as a gap length). The electrodes are sequentially displaced from the smaller one and come into contact with the individual electrodes. Such contact caused by the displacement / deformation of the diaphragm is hereinafter referred to as “coupled contact”. Therefore, compared to conventional electrostatic actuators with parallel plate electrodes, the multi-stage electrostatic actuator has a gap length that changes stepwise, so that the displacement of the diaphragm can be reduced without causing an increase in drive voltage. Can be increased.
However, in the electrostatic actuator having a multi-stage structure, since the diaphragm abuts stepwise from the upper stage, it is necessary to use a high-hardness insulating film as the insulating film provided at the uppermost stage. According to the study by the present inventors, in a system in which the SiO ₂ insulating films are in contact with and separated from each other, the insulating film is worn away and becomes a foreign object by repeating the contact and separation. There was a problem that the driving ability was greatly reduced.

  Therefore, as a means for improving the drive durability of the electrostatic actuator, an electrostatic actuator having a diamond-like carbon film (DLC film) having a high hardness and a low friction coefficient on the contact surface has been proposed (for example, a patent) Reference 4).

JP 2000-318155 A JP 2006-289944 A JP 2007-105860 A JP 2008-018706 A

  By the way, recent ink jet heads have a strong demand for higher density, and as a result, nozzle diameters are becoming increasingly smaller, and electrostatic actuators are also becoming smaller. Therefore, in an inkjet head having such a small diameter nozzle hole, it is necessary to increase the drive voltage of the electrostatic actuator in order to enable ejection of ink droplets. However, when driving at a higher voltage than the conventional driving voltage, for example, 60 V, even if the DLC film is provided on the contact surface of the individual electrode, depending on the electrical characteristics of the DLC film, it may be There is a problem in that the electric actuator is charged and normal drive characteristics cannot be maintained for a long time.

  In view of the problems of the prior art, the present invention provides an electrostatic actuator, a droplet discharge head, and their excellent driving durability, high voltage driving, high density, and excellent process adaptability. It is an object to provide a manufacturing method and a droplet discharge device.

  An electrostatic actuator according to the present invention includes a fixed electrode formed on a substrate, and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween, and the opposing surface of the fixed electrode has a stepped multi-stage. In the electrostatic actuator formed in the structure, surface protective films having different physical properties are formed on the uppermost and lowermost stages of the opposing surface of the fixed electrode.

  In this way, by forming a surface protective film with different physical properties on the uppermost and lowermost surfaces of the opposed surface of the fixed electrode having a multi-stage structure, it is possible to prevent the insulating film from being worn due to contact and detachment of the movable electrode. It is possible to prevent the film from becoming a foreign substance and to prevent the electrostatic actuator from being charged. Therefore, it is possible to realize an electrostatic actuator that is excellent in driving durability, can be driven at a high voltage, and can cope with high density.

  In the electrostatic actuator of the present invention, the surface protective film is preferably a diamond-like carbon film (hereinafter referred to as a DLC film).

The uppermost surface protective film is preferably a DLC film having the highest hardness, and the lowermost surface protective film is preferably a DLC film having the highest volume resistivity.
In the electrostatic actuator having a multi-stage structure, the uppermost stage has the highest contact pressure of the movable electrode, and therefore the uppermost surface protective film is suitably a DLC film having the highest hardness. In addition, since the lowermost stage is highly likely to be charged when driven at a high voltage, the lowermost surface protective film is suitably a DLC film having the highest volume resistivity. Here, the volume resistivity refers to an electrical resistance value per unit volume, and is the same concept as the electrical resistivity in the case of a conductor.

  The surface protective film is formed on an insulating film formed on the fixed electrode. Since the surface protective film is a DLC film, it is desirable to interpose an insulating film as a base film in order to prevent peeling of the surface protective film.

There are the following three methods for constructing a multistage electrostatic actuator.
(1) The substrate on which the fixed electrode is formed is formed in a stepped multi-stage structure.
(2) An insulating film formed on the fixed electrode is formed in a stepped multistage structure.
(3) The surface protective film formed on the fixed electrode is formed in a stepped multistage structure.
The method (1) can be formed at a low cost because it can be formed in multiple stages by repeating patterning and etching of the glass substrate, for example.
Since the method (2) can be formed in multiple stages by repeating patterning and etching of the silicon oxide film, for example, the step can be formed with higher precision than in (1). Therefore, there is little variation in coupled contact, and the discharge characteristics are improved.
In the method (3), since the surface protective film having the desired film characteristics can be formed in multiple stages by using the CVD method, an electrostatic actuator excellent in process adaptability can be realized at low cost.

  As described above, a silicon oxide film is suitable for the insulating film as the base film of the surface protective film. This is because the silicon oxide film can ensure the required withstand voltage and bonding strength.

The insulating film can also be formed of a dielectric material having a relative dielectric constant higher than that of silicon oxide.
When a dielectric material having a relative dielectric constant larger than that of silicon oxide, a so-called High-k material, is used as the insulating film, the generated pressure of the electrostatic actuator can be improved, so that the electrostatic actuator can be miniaturized and densified. .
Among the high-k materials, from the viewpoints of process suitability, film quality stability, etc., in particular, as a dielectric material having a higher dielectric constant than silicon oxide, aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), Hafnium nitride silicate (HfSiN) and oxynitride hafnium silicate (HfSiON) are desirable, and at least one of them may be selected.

A first manufacturing method of an electrostatic actuator according to the present invention includes a fixed electrode formed on a glass substrate, and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween. In the manufacturing method of the electrostatic actuator in which the opposing surface is formed in a stepped multistage structure,
Forming a recess in the glass substrate, forming a bottom surface of the recess into a stepped multi-stage structure, forming a fixed electrode on the bottom surface of the recess, forming an insulating film on the fixed electrode, and insulating Two types of surface protection films with different physical properties are formed on the film, and the surface protection film is selectively removed by patterning and etching, so that the top layer has the highest hardness and the bottom layer has volume resistance. A surface protection film having the highest rate.
According to the first manufacturing method, since the bottom surface of the concave portion of the glass substrate for forming the fixed electrode is formed in multiple stages, an electrostatic actuator excellent in driving durability can be manufactured at low cost.

A second method for manufacturing an electrostatic actuator according to the present invention includes a fixed electrode formed on a glass substrate, and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween. In the manufacturing method of the electrostatic actuator in which the opposing surface is formed in a stepped multistage structure,
Forming a recess in the glass substrate, forming the fixed electrode on the bottom surface of the recess, forming an insulating film on the fixed electrode, forming the insulating film in a stepped multistage structure, and an insulating film On top of this, two types of surface protection films with different physical properties are formed, and the surface protection film is selectively removed by patterning and etching, so that the top layer has the highest hardness and the bottom layer has volume resistivity. Having the highest surface protective film.
According to the second manufacturing method, since the insulating film formed on the fixed electrode is formed in multiple stages, an electrostatic actuator having improved step accuracy and excellent driving durability can be manufactured at low cost. Can do.

A third method for manufacturing an electrostatic actuator according to the present invention includes a fixed electrode formed on a glass substrate, and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween. In the manufacturing method of the electrostatic actuator in which the opposing surface is formed in a stepped multistage structure,
Forming recesses in the glass substrate, forming a fixed electrode on the bottom surface of the recess, forming an insulating film on the fixed electrode, and forming two types of surface protective films with different physical properties on the insulating film In addition, by selectively removing the surface protective film by patterning and etching, the uppermost stage is a surface protective film having the highest hardness and the lowermost stage is a surface protective film having the highest volume resistivity.
According to the third manufacturing method, since two types of surface protective films having different physical properties formed on the insulating film on the fixed electrode are formed in multiple stages, the process adaptability is excellent and the driving durability is improved. An excellent electrostatic actuator can be manufactured at low cost.

The surface protective film is formed by the RF-CVD method, and two kinds of surface protective films having different physical properties are formed by changing the RF output during film formation or during film formation.
In the case of a DLC film, a high hardness, low volume resistivity, and a high friction coefficient DLC film are obtained when the RF output is increased, and a low hardness and high volume resistivity are obtained when the RF output is decreased. A DLC film having a low friction coefficient can be obtained. Therefore, in an electrostatic actuator having a multi-stage structure, films are formed with different RF outputs so that the uppermost stage is a high-hardness DLC film and the lowermost stage is a high volume resistivity DLC film.

A droplet discharge head according to the present invention is one in which any one of the electrostatic actuators described above is mounted.
Accordingly, it is possible to realize a droplet discharge head that has excellent driving durability, can be driven at a high voltage, and can cope with high density.

A method of manufacturing a droplet discharge head according to the present invention is a method of manufacturing a droplet discharge head by applying any one of the above-described electrostatic actuator manufacturing methods.
As a result, a droplet discharge head that has excellent driving durability, can be driven at a high voltage, and can cope with high density can be manufactured at low cost.

  A droplet discharge apparatus according to the present invention is equipped with the above-described droplet discharge head. Therefore, it is possible to provide a droplet discharge device that is excellent in driving durability, can be driven at a high voltage, and can cope with high density.

1 is an exploded perspective view showing a schematic configuration of an inkjet head according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of an inkjet head showing a schematic configuration of a substantially right half of FIG. 1 in an assembled state. The AA expanded sectional view of FIG. FIG. 3 is a top view of the inkjet head of FIG. 2. FIG. 3 is a schematic cross-sectional view of the manufacturing process of the electrode substrate of the inkjet head according to the first embodiment. FIG. 3 is a schematic cross-sectional view of the manufacturing process of the inkjet head according to the first embodiment. FIG. 6 is a schematic cross-sectional view of an inkjet head according to Embodiment 2 of the present invention. BB expanded sectional view of FIG. FIG. 5 is a schematic cross-sectional view of an inkjet head according to Embodiment 3 of the present invention. FIG. 10 is a schematic cross-sectional view of a manufacturing process of an electrode substrate of an ink jet head according to Embodiment 3. FIG. 6 is a schematic cross-sectional view of an ink jet head according to Embodiment 4 of the present invention. 6 is a schematic cross-sectional view of a manufacturing process of an electrode substrate of an ink jet head according to Embodiment 4. FIG. FIG. 7 is a schematic cross-sectional view of an ink jet head according to a fifth embodiment of the present invention. FIG. 7 is a schematic cross-sectional view of an inkjet head according to a sixth embodiment of the present invention. 1 is a schematic perspective view showing an example of an ink jet printer to which an ink jet head of the present invention is applied.

  Hereinafter, embodiments of a droplet discharge head including an electrostatic actuator to which the present invention is applied will be described with reference to the drawings. Here, as an example of a droplet discharge head, a face discharge type electrostatic drive type inkjet head that discharges ink droplets from nozzle holes provided on the surface of a nozzle substrate will be described with reference to FIGS. . Note that the present invention is not limited to the structure and shape shown in the following drawings, and has a four-layer structure in which four substrates each having a discharge chamber and a reservoir portion provided on separate substrates are laminated, The present invention can be similarly applied to an edge discharge type droplet discharge head that discharges ink droplets from a nozzle hole provided at the end of the nozzle.

Embodiment 1 FIG.
FIG. 1 is an exploded perspective view showing an exploded schematic configuration of an ink jet head according to Embodiment 1 of the present invention, and a part thereof is shown in cross section. 2 is a cross-sectional view of the inkjet head showing a schematic configuration of the substantially right half of FIG. 1 in an assembled state (however, the configuration of the multi-stage individual electrode is different from that of FIG. 1). 3 is an AA enlarged sectional view of FIG. 2, and FIG. 4 is a top view of the inkjet head of FIG. 1 and 2 are shown upside down from a state in which they are normally used.

  As shown in FIGS. 1 to 4, the inkjet head 10 according to the first embodiment includes a nozzle substrate 1 in which a plurality of nozzle holes 11 are provided at a predetermined pitch, and ink independently for each nozzle hole 11. The cavity substrate 2 provided with the supply path and the electrode substrate 3 provided with the individual electrodes 5 having a multistage structure facing the diaphragm 6 provided on the cavity substrate 2 are bonded together.

  Here, the opposing surface of the individual electrode 5 has a multi-stage structure in which a required number of steps are provided in a step shape. Note that the number of steps is arbitrary, but in the present embodiment, it is composed of two steps for easy understanding. In the case of the present embodiment, the electrode substrate 3 on which the individual electrodes 5 are formed has a two-stage structure. For example, a plurality of narrow groove-like recesses 32 and 32 a are formed on the glass substrate, and the second recess 32 a is formed on the bottom surface of the recess 32, thereby forming the bottom surface of the recess 32 in a multistage structure. Then, by patterning, for example, an ITO (Indium Tin Oxide) film on the stepped bottom surface of the recess 32, the individual electrode 5 is formed in a multistage structure having two or more steps.

The individual electrode 5 has an electrode portion 5a facing the diaphragm 6, a lead portion 5b extending toward the end of the substrate, and a terminal portion 5c connected to a flexible printed circuit board (FPC) (not shown). The electrode portion 5a is formed in multiple stages in the longitudinal direction.
Further, an insulating film 7 made of a silicon oxide film (SiO ₂ film) is formed on the individual electrode 5, and two types of first surface protective films having different physical properties are formed on the lowermost and uppermost insulating films 7. 8a and a second surface protective film 8b are formed.

  Here, the first surface protective film 8a formed in the lowest stage (second stage) having the largest gap length with the diaphragm 6 is a DLC film having the highest volume resistivity. The second surface protective film 8b formed in the uppermost stage (first stage) having the smallest gap length is a DLC film having the highest hardness.

  The diaphragm 6 disposed to face the individual electrode 5 with a predetermined gap G is formed by the bottom wall of the discharge chamber 21 of the cavity substrate 2 made of silicon. In order to prevent dielectric breakdown, short circuit, etc., an insulating film 9 made of a thermal oxide film of silicon is formed.

  The step distance can be arbitrarily set, but is preferably 20% or less of the first (top) gap length G1. If the level difference is too large, the diaphragm 6 will not be in contact with the coupling and the effects of the present invention will not be obtained. In the case of the first embodiment, the thickness of the insulating film 9 on the diaphragm 6 side is 110 nm, the thickness of the insulating film 7 on the individual electrode 5 side is 40 nm, the first-stage gap length G1 is 200 nm, the step is 40 nm, The thickness of the DLC film to be the second surface protective films 8a and 8b is 10 nm each.

The electrostatic actuator 4 having a multi-stage structure is configured for each nozzle hole 11 with the individual electrode 5 having the multi-stage structure configured as described above and the diaphragm 6 disposed to face the individual electrode 5 with a predetermined gap G interposed therebetween. Is done. The individual electrode 5 is generally formed of ITO (Indium Tin Oxide), which is a transparent electrode, but is not particularly limited thereto. A transparent electrode made of IZO (Indium Zinc Oxide) or a metal such as Au or Al may be used. Further, depending on the electrode material of the individual electrode 5, the insulating film 7 can be omitted, and the first and second surface protective films 8a and 8b are directly formed on the individual electrode 5 having a multistage structure.
As shown in FIG. 4 in a simplified manner in the terminal portion 5c of the individual electrode 5 configured as described above and the common electrode 26 provided on the cavity substrate 2, a driver IC is used as a driving means for the electrostatic actuator 4. The drive control circuit 40 such as is connected by wiring through the FPC.

The configuration of each substrate will be described in more detail.
The nozzle substrate 1 is made of, for example, a silicon substrate. The nozzle holes 11 for ejecting ink droplets are, for example, nozzle hole portions formed in a two-stage coaxial cylindrical shape having different diameters, that is, an ejection port portion 11a having a smaller diameter and an inlet port portion 11b having a larger diameter. It is composed of The ejection port portion 11a and the introduction port portion 11b are provided perpendicular to and coaxially with the substrate surface, and the ejection port portion 11a has a leading end that opens on the surface (ink ejection surface) of the nozzle substrate 1, and the introduction port portion. 11b is opened on the back surface of the nozzle substrate 1 (the surface on the bonding side to be bonded to the cavity substrate 2).
In addition, the nozzle substrate 1 is formed with an orifice 12 for communicating the discharge chamber 21 of the cavity substrate 2 and the reservoir 23 and a diaphragm portion 13 for compensating for pressure fluctuations in the reservoir 23 portion.

  By forming the nozzle hole 11 in two stages from the ejection port portion 11a and the inlet port portion 11b having a larger diameter than this, the ink droplet ejection direction can be aligned with the central axis direction of the nozzle hole 11 and stable. Ink discharge characteristics can be exhibited. That is, there is no variation in the flying direction of the ink droplets, there is no scattering of the ink droplets, and variation in the ejection amount of the ink droplets can be suppressed. In addition, the nozzle density can be increased.

  The cavity substrate 2 bonded to the electrode substrate 3 is made of, for example, a silicon substrate having a plane orientation of (110). The cavity substrate 2 is formed by etching with a recess 22 serving as a discharge chamber 21 provided in the ink flow path and a recess 24 serving as a reservoir 23. A plurality of recesses 22 are independently formed at positions corresponding to the nozzle holes 11. Therefore, as shown in FIG. 2, when the nozzle substrate 1 and the cavity substrate 2 are joined, each concave portion 22 constitutes a discharge chamber 21 and communicates with each nozzle hole 11 and the orifice 12 serving as an ink supply port. Both communicate with each other. The bottom of the discharge chamber 21 (concave portion 22) is the diaphragm 6. The diaphragm 6 is formed of a boron diffusion layer in which a high concentration of boron (B) is diffused on the surface of the silicon substrate, and the thickness of the boron diffusion layer is the same as the thickness of the diaphragm 6. It is. This is because, when the discharge chamber 21 is formed by anisotropic wet etching with alkali, the etching rate becomes extremely small when the boron diffusion layer is exposed. This is because it can be formed with high accuracy.

  The recess 24 is for storing a liquid material such as ink, and constitutes a reservoir (common ink chamber) 23 common to the ejection chambers 21. The reservoirs 23 (recesses 24) communicate with all the discharge chambers 21 through the orifices 12, respectively. A hole penetrating the electrode substrate 3 is provided at the bottom of the reservoir 23, and ink is supplied from an ink cartridge (not shown) through the ink supply hole 33 of the hole.

  The electrode substrate 3 is produced from a glass substrate. Among them, it is suitable to use a borosilicate heat-resistant hard glass having a thermal expansion coefficient close to that of the silicon substrate of the cavity substrate 2. This is because when the electrode substrate 3 and the cavity substrate 2 are anodically bonded, the thermal expansion coefficients of the two substrates are close to each other, so that the stress generated between the electrode substrate 3 and the cavity substrate 2 can be reduced. This is because the electrode substrate 3 and the cavity substrate 2 can be firmly bonded without causing the above problem.

  The electrode substrate 3 and the cavity substrate 2 manufactured as described above are anodically bonded, and the nozzle substrate 1 is bonded and bonded thereon, whereby the main body of the inkjet head 10 is completed as shown in FIG. Thereafter, the drive control circuit 40 is wired to each individual electrode 5 and the common electrode 26 using FPC. Further, the electrode extraction portion (also referred to as FRP mounting portion) 34 is hermetically sealed by, for example, applying a sealing material 35 such as an epoxy resin to the open end portion of the gap of the electrostatic actuator 4. As a result, it is possible to reliably prevent moisture, foreign matter, and the like from entering the gap of the electrostatic actuator 4, thereby realizing driving stability and durability. That is, the reliability of the inkjet head 10 is improved.

Next, the operation of the inkjet head 10 configured as described above will be described.
When a pulse voltage is applied between the individual electrode 5 and the common electrode 26 of the cavity substrate 2 by the drive control circuit 40, the diaphragm 6 is attracted and attracted to the individual electrode 5 side by electrostatic attraction. At this time, since the first and second surface protective films 8a and 8b are formed on the multi-layered individual electrode 5 via the insulating film 7, the diaphragm 6 has a smaller gap length, that is, FIG. The second surface protective film 8b comes into contact with the first surface protective film 8a at the deepest portion (second step) from the upper stage. In other words, by applying a voltage sufficient to fill the gap length G1 in the upper stage, the diaphragm 6 contacts the second surface protective film 8b, and the gap length G−G1 = t (t: The diaphragm 6 is brought into contact with the first surface protective film 8a by applying a voltage sufficient to fill the step. In this way, the diaphragm 6 is in abutting contact while sequentially contacting the end of each step according to the number of steps of the multi-stage structure of the opposing surface of the individual electrode 5. When the vibration plate 6 is displaced by the coupled contact, a negative pressure is generated in the discharge chamber 21, the ink in the reservoir 23 is sucked, and ink vibration (meniscus vibration) is generated. When the voltage of the ink is released when the vibration of the ink becomes substantially maximum, the vibration plate 6 is detached, the ink is pushed out from the nozzle 11, and the ink droplet is ejected.

  Therefore, according to the electrostatic actuator 4 of the present embodiment, the opposing surface of the individual electrode 5 has a multistage structure, and the second surface protection made of a DLC film having a high hardness is provided at the uppermost stage (first stage). Since the film 8b is formed, the uppermost second surface protective film 8b in which the contact force of the diaphragm 6 is increased is not worn, and the formation of foreign matter in the film can be suppressed. Even when driven at a high voltage, since the lowermost first surface protective film 8a is a DLC film having a high volume resistivity, charging is unlikely to occur. Therefore, the electrostatic actuator 4 that can be driven at high voltage and has long-term driving durability can be realized. Further, since high voltage driving is possible, higher density can be achieved.

In addition, the average pressure P of the electrostatic actuator increases as the relative dielectric constant ε of the insulating film (including the surface protective film) increases, or as the ratio (t / ε) of the relative dielectric constant ε to the thickness t of the insulating film decreases. _e is known to be high. Since silicon oxide has a relative dielectric constant larger than that of air, a portion having a narrow gap formed by multiple stages can increase a generated pressure of the electrostatic actuator as compared with a portion having a wide gap.
That is, when a voltage is applied to the electrostatic actuator according to the present invention, the coupled contact is generated from a portion where the generated pressure is relatively large and the insulating film thickness is thick. The electrostatic actuator can be brought into contact with a voltage of. In addition, it is possible to further improve dielectric breakdown strength such as TDDB (Time Dependent Dielectric Breakdown, long-time dielectric breakdown strength) and TZDB (Time Zero Dielectric Breakdown, instantaneous dielectric breakdown strength) in the electrostatic actuator. Further, when compared with the same contact voltage, the volume change amount of the discharge chamber can be increased, and a large ink rejection volume can be ensured.

Further, when a DLC film is formed as a surface protective film of the individual electrode 5 by RF-CVD (Chemical Vapor Deposition) method, as a result of examination by the present inventors regarding the physical properties of the DLC film, depending on the RF output value at the time of film formation, It was found that the film quality changed greatly.
Specifically, when the RF output is large, that is, when the energy applied to the raw material gas is large, the decomposition of the raw material gas proceeds sufficiently. Therefore, sufficient DLC conversion is promoted, and a more uniform DLC film can be obtained. However, since the hydrogen atoms contained in the source gas are released during the decomposition process, the film becomes a DLC film having a relatively high friction coefficient, high hardness, and low volume resistivity. Conversely, when the RF output is small, that is, when the energy applied to the raw material gas is small, the decomposition of the raw material gas does not proceed sufficiently. Therefore, sufficient DLC conversion is not promoted, hydrogen atoms contained in the raw material gas are not easily separated during the decomposition process, and the film becomes a DLC film having a relatively low friction coefficient, low hardness, and high volume resistivity.

In the electrostatic actuator having a multi-stage structure, the gap between the diaphragm 6 and the first-stage DLC film (first-stage gap length G1) is very wide, and the first and second-stage steps are located in the gap (G1). Smaller than that. Therefore, the pressure applied to the DLC film on the individual electrode 5 side when the diaphragm 6 abuts is considerably larger at the first stage abutment than at the second stage abutment. However, the contact and retention characteristics of the diaphragm 6 are largely related to the contact state of the second stage.
Therefore, it is desirable to use a hard DLC film for the first stage (uppermost stage), and it is desirable to use a DLC film having a high volume resistivity that is difficult to be charged for the second stage (lowermost stage).

(Inkjet head manufacturing method)
Next, an outline of an example of a method for manufacturing the inkjet head 10 according to Embodiment 1 will be described with reference to FIGS.
FIG. 5 is a partial cross-sectional view showing the manufacturing process of the electrode substrate of the ink jet head 10 according to the first embodiment, and shows a part of a plurality of wafer substrates formed on the wafer-like glass substrate. FIG. 6 is a partial cross-sectional view of the manufacturing process of the inkjet head 10 according to the first embodiment, and shows a cross-section of a portion of the silicon wafer. In addition, the numerical value about the thickness of a board | substrate described below, a film thickness, an etching depth, etc. shows the example, and is not limited to this.

First, a method for manufacturing the electrode substrate 3 according to Embodiment 1 will be described.
(A) A recess 32 having a desired depth is formed on a glass substrate 300 made of borosilicate glass or the like with a thickness of about 1 mm by etching with hydrofluoric acid using, for example, an etching mask made of gold or chromium. Furthermore, a required step is formed by forming a second recess 32a on the bottom surface of the recess 32 (FIG. 5A). The recesses 32, 32 a have a groove shape slightly larger than the shape of the individual electrode 5, and a plurality of the recesses 32, 32 a are formed for each individual electrode 5.

(B) Next, for example, an ITO (Indium Tin Oxide) film is formed with a thickness of 100 nm by a sputtering method, and this ITO film is patterned by photolithography to remove the portions other than the individual electrode 5 by etching, The individual electrode 5 having a multistage structure is formed inside the recesses 32 and 32a (FIG. 5B).

(C) Next, RF-CVD (Chemical Vapor Deposition) using TEOS (Tetraethoxysilane) as a source gas from the bonding surface side of the glass substrate 300 as the insulating film 7 on the individual electrode 5 having a multistage structure. A SiO ₂ film having a thickness of 40 nm is formed on the entire surface by a method (hereinafter referred to as TEOS-CVD method). Then, on the insulating film 7 of the SiO ₂ film, a DLC film having a high hardness is formed as a second surface protective film 8b by 10 nm over the entire surface by RF-CVD (FIG. 5C). The conditions for forming the DLC film are as follows.
Source gas: Toluene, RF output: 600 W, Source gas flow rate: 5 sccm.
Further, the volume resistivity of this DLC film was 8 × 10 ¹¹ Ωcm. However, it is a measurement value when the film thickness is 100 nm and the measurement voltage is 10V.
The film hardness was 83.6 nm when measured with an indentation load of 2 mN using “Nanoindenter ENT-1100a (manufactured by Elionix)” as a measuring device.

(D) Next, since the DLC film cannot be anodically bonded, the other DLC film portion is left with CHF ₃ gas so as to leave only the first-stage DLC film (second surface protective film 8b) of the individual electrode 5. This is removed by RIE (Reactive Ion Etching) using dry etching. That is, a resist is applied to the DLC film formed on the entire surface, and patterning is performed by photolithography, so that the second stage, the DLC film (first terminal 5c) of the bonding part 36 and the electrode extraction part 34 (the terminal part 5c of the individual electrode 5) Only the surface protective film 8b) part 2 is removed by RIE dry etching using CHF ₃ gas (FIG. 5D).

(E) Next, as the first surface protective film 8a, a DLC film having a high volume resistivity is formed on the entire surface by 10 nm by RF-CVD (FIG. 5E). The conditions for forming the DLC film are as follows.
Source gas: Toluene, RF output: 300 W, Source gas flow rate: 5 sccm.
The volume resistivity of this DLC film was 3 × 10 ¹⁴ Ωcm. However, it is a measurement value when the film thickness is 100 nm and the measurement voltage is 10V.
The film hardness was 94.8 nm when measured with an indentation load of 2 mN using “Nanoindenter ENT-1100a (manufactured by Elionix)” as a measuring device. In addition, the one where the value of indentation depth is small has shown that it is hard (high hardness). Therefore, the second surface protective film 8b has higher hardness than the first surface protective film 8a.

(F) Then, patterning is performed so that only the second-stage DLC film (first surface protective film 8a) remains, and the other DLC film portions are removed by RIE dry etching using CHF ₃ gas (FIG. 5 (f)).

(G) Thereafter, the insulating film 7 (SiO ₂ film) of the electrode extraction portion 34 is removed by RIE dry etching using CHF ₃ gas using the silicon mask in which the electrode extraction portion 34 of the removal portion is opened (FIG. 5 ( g)). Finally, a hole 33a to be the ink supply hole 33 is formed in the glass substrate 300 by blasting or the like.

  Next, with reference to FIG. 6, the manufacturing method of the inkjet head 10 which concerns on Embodiment 1 is demonstrated. Here, the manufacturing method of the cavity substrate 2 is mainly shown. The cavity substrate 2 is manufactured after the silicon substrate 200 is anodically bonded to the electrode glass substrate 300A manufactured as described above.

(A) First, a silicon substrate 200 in which, for example, a boron diffusion layer 201 having a thickness of 0.8 μm is formed on the entire surface of one side of the silicon substrate 200 having a thickness of 280 μm, for example. Next, on the surface of the boron diffusion layer 201 of the silicon substrate 200, a SiO ₂ film having a thickness of 110 nm is formed as an insulating film 9 by a thermal oxidation method (FIG. 6A).

(B) Next, the silicon substrate 200 is aligned on the electrode glass substrate 300A and anodic bonded (FIG. 6B).
(C) Next, the entire surface of the bonded silicon substrate 200 is polished to reduce the thickness to, for example, about 50 μm (FIG. 6C), and the entire surface of the silicon substrate 200 is written by wet etching. Etch to remove processing marks.

(D) Next, resist patterning is performed by photolithography on the surface of the bonded silicon substrate 200 processed into a thin plate, and ink flow channel grooves are formed by anisotropic wet etching using an aqueous KOH solution. As a result, a recess 22 serving as the discharge chamber 21 having the bottom wall as the diaphragm 6, a recess 24 serving as the reservoir 23, and a recess 27 serving as the electrode extraction portion 34 are formed (FIG. 6D). At this time, since etching is stopped on the surface of the boron diffusion layer 201, the thickness of the diaphragm 6 can be formed with high accuracy and surface roughness can be prevented.

(E) Next, the bottom of the concave portion 27 is removed by RIE (Reactive Ion Etching) dry etching using CHF ₃ gas to open the electrode lead-out portion 34 (FIG. 6E). Thereafter, moisture adhering to the inside of the electrostatic actuator is removed. For the moisture removal, the silicon substrate is placed in, for example, a vacuum chamber, and the moisture is removed by heating and vacuuming.
(F) Then, after the required time has elapsed, nitrogen gas is introduced, and a sealing material 35 such as an epoxy resin is applied to the external communication portion of the gap in a nitrogen atmosphere to seal it hermetically (FIG. 6 (f)).
Further, the ink supply hole 33 is formed by penetrating the bottom of the recess 24 by microblasting or the like. Further, to prevent corrosion of the ink flow path grooves to form ink protective film made of TEOS-SiO ₂ film (not shown) by a plasma CVD method on the surface of the silicon substrate. A common electrode 26 made of metal is formed on the silicon substrate.

The cavity substrate 2 is manufactured from the silicon substrate 200 bonded to the electrode substrate 3 through the above steps.
(G) Thereafter, the nozzle substrate 1 in which the nozzle holes 11 and the like are separately formed is bonded on the surface of the cavity substrate 2 by adhesion. Finally, when the individual head chips are cut by dicing, the above-described main body of the inkjet head 10 is completed (FIG. 6G).

According to the method for manufacturing the inkjet head 10 according to the first embodiment, the first surface protective film having a high volume resistivity is obtained by changing the RF output when the DLC film is formed by the RF-CVD method. 8a can be selectively deposited on the bottommost second stage and the high hardness second surface protective film 8b can be selectively deposited on the topmost stage, so that it has excellent driving durability and high voltage driving. The inkjet head 10 that can cope with high density can be manufactured at low cost.
Further, since the cavity substrate 2 is manufactured from the silicon substrate 200 bonded to the electrode glass substrate 300A separately manufactured, the silicon substrate 200 is supported by the electrode glass substrate 300A, and the silicon substrate 200 is thinned. It is easy to handle without cracking or chipping. Accordingly, the yield is improved as compared with the case where the cavity substrate 2 is manufactured alone.

Embodiment 2. FIG.
7 is a schematic cross-sectional view of an ink jet head according to Embodiment 2 of the present invention, and FIG. 8 is an enlarged cross-sectional view taken along line BB of FIG. In the second and subsequent embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In the second embodiment, a third surface protective film 8c having the same high volume resistivity as that of the first surface protective film 8a is formed on the insulating film 9 on the diaphragm 6 side. The same as in the first embodiment. However, since the DLC film serving as the third surface protective film 8c cannot be anodically bonded, the third surface protective film 8c is formed only on the opposing surface of the diaphragm 6 as shown in FIG. The thickness of the third surface protective film 8c is set to 10 nm similarly to the first and second surface protective films 8a and 8b.

  As described above, when the DLC film is provided on both the abutting surface (opposing surface) of the diaphragm 6 and the individual electrode 5, if the insulating property of the abutting surface insulating film is low, electric field holding at the time of abutting is insufficient. It becomes. Therefore, it is desirable that the contact surface be formed from a highly insulating film. In particular, in high voltage driving, it is desirable to have high insulation properties corresponding to the driving voltage. Note that whether or not the diaphragm 6 can be held in contact greatly varies depending on the drive voltage, drive waveform, actuator design, and the like, and therefore cannot be said to be an optimum value. From the viewpoint of mechanical properties, a DLC film having a low friction coefficient and a high hardness is desirable.

In the manufacturing method of the ink jet head 10 of the present embodiment, the electrode substrate 3 is manufactured by the same method as in FIG. The cavity substrate 2 is basically the same as that shown in FIG. 6, and a silicon substrate 200 in which the third surface protective film 8 c is patterned only on the opposing surface of the diaphragm 6 in FIG. The third surface protective film 8c may be formed by forming a DLC film on the entire surface, patterning the facing surface of the diaphragm 6, and removing the DLC film portion other than the facing surface by RIE dry etching using CHF ₃ gas. .

  In the present embodiment, the third and first surfaces have the same effects as those of the first embodiment, and the contact surfaces of the diaphragm 6 and the individual electrodes 5 are formed of a DLC film having a high volume resistivity. Since the protective films 8c and 8a are used, it is possible to realize the inkjet head 10 that can be driven at a higher voltage.

Embodiment 3 FIG.
FIG. 9 is a schematic cross-sectional view of an ink jet head according to Embodiment 3 of the present invention.
In the third embodiment, insulating films 7 (SiO ₂ films) formed on the individual electrodes 5 are formed in multiple stages. Therefore, in the case of the present embodiment, the bottom surface of the recess 32 is flat, and the individual electrode 5 formed on the bottom surface also has a flat surface. The insulating film 7 on the individual electrode 5 is formed of a first-stage insulating film 7a and a second-stage insulating film 7b, both of which are formed from a SiO ₂ film. The diaphragm 6 side has the same configuration as that of the second embodiment, and a third surface protective film 8c made of a DLC film having a high volume resistivity is formed only on the opposing surface on the insulating film 9. As for the film thickness and the like, the thickness of the insulating film 9 on the diaphragm 6 side is 90 nm, the thickness of the insulating film 7 on the individual electrode 5 side is 60 nm (first stage, second stage insulating film: 30 nm each), one stage The eye gap length G1 is 200 nm, the step is 30 nm, and the thicknesses of the DLC films of the first to third surface protective films 8a, 8b, and 8c are 10 nm.

FIG. 10 is a schematic cross-sectional view showing the manufacturing process of the electrode substrate of the ink jet head according to the third embodiment.
First, as shown in FIG. 10A, a recess 32 having a desired depth is formed on a glass substrate 300 made of borosilicate glass or the like by etching with hydrofluoric acid using, for example, an etching mask made of gold or chromium. To do. Then, for example, an ITO film is formed with a thickness of 100 nm by a sputtering method, and this ITO film is patterned by photolithography, and the portions other than the individual electrodes 5 are removed by etching, so that the surface is flat inside the recess 32. Individual electrodes 5 are formed.

Next, as shown in FIG. 10B, as the insulating film 7 on the individual electrode 5, a SiO ₂ film with a thickness of 60 nm is formed from the bonding surface side of the glass substrate 300 by a TEOS-CVD method. .

Next, as shown in FIG. 10C, a resist is applied to the SiO ₂ film formed on the entire surface, and the first patterning is performed by photolithography. In the patterning, a resist is opened so that the formation of the first-stage insulating film 7a and the SiO ₂ film of the electrode extraction portion 34 are partially removed.

Next, as shown in FIG. 10D, the remaining SiO ₂ film of the electrode lead-out portion 34 is removed by RIE dry etching using CHF ₃ gas using a silicon mask in which the electrode lead-out portion 34 of the removal portion is opened. Remove.

Next, as shown in FIG. 10E, a high-hardness DLC film is formed by RF-CVD as a second surface protective film 8b on the SiO ₂ film on which the first and second stages are formed. The entire surface is formed. Thereafter, the DLC film deposition method and deposition conditions are as described in FIGS. 5C to 5F of the first embodiment.

That is, as shown in FIG. 10 (f), patterning is performed so as to leave only the first-stage DLC film (second surface protective film 8b), and the other DLC film portion is subjected to RIE drying using CHF ₃ gas. Remove by etching. Finally, as shown in FIG. 10 (g), as the first surface protective film 8a, a DLC film having a high volume resistivity is formed on the entire surface by RF-CVD, and then the electrode extraction portion 34 is opened. Using the silicon mask, the SiO ₂ film of the electrode extraction portion 34 is removed by RIE dry etching using CHF ₃ gas.

As described above, the insulating films 7 on the individual electrodes 5 are formed in multiple stages, the high hardness second surface protective film 8b is formed on the first stage insulating film 7a, and the high volume resistance is formed on the second stage insulating film 7b. The electrode glass substrate 300B on which the first surface protective film 8a having a high rate is formed.
And if it replaces with electrode glass substrate 300A of FIG. 6 and uses electrode glass substrate 300B produced by the above, the inkjet head 10 of this Embodiment can be manufactured as shown in FIG.

  According to the third embodiment, in addition to the effects of the first embodiment, the pressure generated by the actuator can be increased by forming the insulating film 7 in two or more stages. This further contributes to increasing the density of the inkjet head 10. Further, as in the first and second embodiments, the insulating film 7 formed on the individual electrode 5 is formed in multiple stages as compared with the method of forming the bottom surface of the recess 32 in multiple stages by etching. Therefore, the level difference can be formed with high accuracy.

Embodiment 4 FIG.
FIG. 11 is a schematic sectional view of an ink jet head according to Embodiment 4 of the present invention.
In the fourth embodiment, the DLC film formed on the insulating film 7 of the individual electrode 5 is formed in multiple stages. Accordingly, the bottom surface of the recess 32, the individual electrode 5, and the insulating film 7 (SiO ₂ film) are all formed flat. The diaphragm 6 side is the same as that of the second embodiment, and a surface protective film 8c made of a DLC film having a high volume resistivity is formed only on the opposing surface on the insulating film 9. The thickness of the insulating film 9 on the diaphragm 6 side is 110 nm, the thickness of the insulating film 7 on the individual electrode 5 side is 40 nm, the first step gap length G1 is 200 nm, the step is 10 nm, The thickness of each of the DLC films of the third surface protective films 8a, 8b, and 8c is 10 nm.

FIG. 12 is a schematic cross-sectional view showing the manufacturing process of the electrode substrate of the ink jet head according to the fourth embodiment.
In the manufacturing process of the electrode substrate 3, FIGS. 12A and 12B are the same as FIGS. 10A and 10B of the third embodiment. Then, as shown in FIG. 12C, a DLC film having a high volume resistivity is formed on the entire surface of the insulating film 7 (SiO ₂ film) formed on the entire surface by RF-CVD as a first surface protective film 8a. A high hardness DLC film is formed as a second surface protective film 8b on the entire surface by RF-CVD. The film formation conditions for the DLC film are the same as those in the first embodiment, but the first surface protective film 8a and the second surface protective film 8b are stacked in this order by changing the RF output during the film formation of the DLC film. To do.

Next, as shown in FIG. 12D, patterning is performed on the upper (second stage) second surface protective film 8b, and the lower (first stage) first surface protective film 8a is exposed. Thus, the second surface protective film 8b is removed by RIE dry etching using CHF ₃ gas. Thereafter, as shown in FIG. 12E, the insulating film 7 of the electrode lead-out portion 34 is removed by RIE dry etching using CHF ₃ gas using a silicon mask having the electrode lead-out portion 34 opened.
And the inkjet head 10 of this Embodiment can be manufactured by producing the cavity board | substrate 2 like FIG. 6 using the electrode glass substrate 300C manufactured in this way.

  In the present embodiment, the first surface protective film 8a and the second surface protective film 8b having desired film characteristics are stacked in this order by changing the RF output during the formation of the DLC film, and Since the first surface protective film 8a is exposed by patterning, it can be formed in multiple stages, and thus the electrostatic actuator 4 having a multistage structure can be manufactured more easily.

Embodiment 5 FIG.
FIG. 13 is a schematic cross-sectional view of an ink jet head according to Embodiment 5 of the present invention.
In the fifth embodiment, a so-called High-k material (high dielectric constant insulating material) such as aluminum oxide (Al ₂ O ₃ , alumina) is used as the insulating film 7 formed on the individual electrode 5. . Alumina has a relative dielectric constant of about 7.9, which is larger than the relative dielectric constant of silicon oxide 3.8, so that the pressure generated by the electrostatic actuator 4 can be further increased. Other configurations are the same as those in the fourth embodiment. Regarding the film thickness and the like, the thickness of the insulating film 9 on the diaphragm 6 side is 110 nm, the thickness of the insulating film 7 (Al ₂ O ₃ ) on the individual electrode 5 side is 40 nm, the first gap length G1 is 200 nm, and the step is Each thickness of the DLC films of 10 nm and the first to third surface protective films 8a, 8b, and 8c is 10 nm.

High-k materials having a relative dielectric constant larger than that of silicon oxide include alumina, silicon oxynitride (SiON), hafnium oxide (HfO ₂ ), tantalum oxide (Ta ₂ O ₃ ), hafnium nitride silicate (HfSiN), Hafnium oxynitride silicate (HfSiON), aluminum nitride (AlN), zirconium nitride (ZrO ₂ ), cerium oxide (CeO ₂ ), titanium oxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), zirconium silicate (ZrSiO), Examples thereof include hafnium silicate (HfSiO), zirconium aluminate (ZrAlO), nitrogen-added hafnium aluminate (HfAlON), and composite films thereof. Among them, when considering low-temperature film formability, film homogeneity, process adaptability, etc., aluminum oxide (Al ₂ O ₃ , alumina), hafnium oxide (HfO ₂ ), hafnium nitride silicate (HfSiN), oxynitride It is desirable to use hafnium silicate (HfSiON), at least one of which is selected.

In order to manufacture the electrode substrate 3 of the present embodiment, for example, after forming the individual electrodes 5 as shown in FIG. 12A, the insulating film 7 is made of Al ₂ by using an ECR (Electron Cyclotron Resonance) sputtering method. An O ₃ film is formed on the entire surface of the glass substrate 300 with a thickness of 40 nm. After that, what is necessary is just to implement like FIG.12 (c)-(e). And the inkjet head 10 of this Embodiment can be manufactured by producing the cavity board | substrate 2 like this FIG. 6 using this electrode substrate 3. FIG.

  In the present embodiment, since the high-k material having a relative dielectric constant larger than that of silicon oxide is used as the insulating film 7 on the individual electrode 5 side, the pressure generated by the electrostatic actuator 4 can be further increased, and the discharge characteristics can be increased. In addition, the electrostatic actuator 4 can be miniaturized and densified.

Embodiment 6 FIG.
FIG. 14 is a schematic sectional view of an ink jet head according to Embodiment 6 of the present invention.
In the first to fifth embodiments so far, the deepest part of the gap length G is provided at the center of the electrode part 5a of the individual electrode 5, but in the sixth embodiment, the tip part of the electrode part 5a is provided. The deepest part of the gap length G is provided (position close to the nozzle hole 11). That is, the step structure of the first and second surface protective films 8 a and 8 b formed on the insulating film 7 on the individual electrode 5 side is formed in a stepped shape from the tip side of the individual electrode 5. As for the film thickness and the like, the thickness of the insulating film 9 on the diaphragm 6 side is 110 nm, the thickness of the insulating film 7 on the individual electrode 5 side is 40 nm, and the first-stage gap length G1 is the same as in the fourth embodiment. The thickness of the DLC film of 200 nm, the level difference of 10 nm, and the surface protective films 8a, 8b, and 8c is 10 nm.

  The electrode substrate 3 of the present embodiment can be manufactured according to FIG. 12, and the inkjet head 10 can also be manufactured according to FIG.

  The sixth embodiment has the same effect as that of the third embodiment. In addition, since the deepest part of the gap length is provided at the tip of the electrode part 5a close to the nozzle hole 11, there is an ink rectifying effect at the time of ejection. It is possible to increase the ink discharge weight. Accordingly, the printing speed is improved.

  In the above embodiment, the electrostatic actuator, the ink jet head, and the manufacturing method thereof have been described. However, the present invention is not limited to the above embodiment, and various modifications are made within the scope of the idea of the present invention. be able to. For example, the electrostatic actuator of the present invention can be used for an optical switch, a mirror device, a micropump, a drive unit of a laser operation mirror of a laser printer, or the like. Further, by changing the liquid material discharged from the nozzle hole, for example, in addition to the ink jet printer 400 as shown in FIG. 15, the manufacture of a color filter of a liquid crystal display, the formation of a light emitting portion of an organic EL display device, a genetic test, etc. It can be used as a droplet discharge device for various uses such as the production of microarrays of biomolecule solutions used in the field.

  1 nozzle substrate, 2 cavity substrate, 3 electrode substrate, 4 electrostatic actuator, 5 individual electrode (fixed electrode), 6 diaphragm (movable electrode), 7 insulating film, 8a first surface protective film, 8b second surface Protective film, 8c Third surface protective film, 9 Insulating film, 10 Inkjet head, 11 Nozzle hole, 12 Orifice, 13 Diaphragm part, 21 Discharge chamber, 23 Reservoir, 26 Common electrode, 32 Recessed part, 32a Second recessed part, 33 Ink supply hole, 34 Electrode extraction part (FPC mounting part), 35 Sealing material, 36 Joint part, 40 Drive control circuit (drive means), 200 Silicon substrate, 300 Glass substrate, 400 Inkjet printer.

Claims (17)

An electrostatic actuator comprising: a fixed electrode formed on a substrate; and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween, wherein the opposing surface of the fixed electrode is formed in a stepped multistage structure Because
An electrostatic actuator, wherein surface protective films having different physical properties are formed on an uppermost stage and a lowermost stage of an opposing surface of the fixed electrode.   The electrostatic actuator according to claim 1, wherein the surface protective film is a diamond-like carbon film.   The static protective film according to claim 2, wherein the uppermost surface protective film is a diamond-like carbon film having the highest hardness, and the lowermost surface protective film is a diamond-like carbon film having the highest volume resistivity. Electric actuator.   The electrostatic actuator according to claim 1, wherein the surface protective film is formed on an insulating film formed on the fixed electrode.   The electrostatic actuator according to claim 1, wherein a portion of the substrate on which the fixed electrode is formed is formed in a stepped multistage structure.   The electrostatic actuator according to claim 4, wherein the insulating film is formed in a stepped multistage structure.   The electrostatic actuator according to claim 1, wherein the surface protective film is formed in a stepped multistage structure.   The electrostatic actuator according to claim 4, wherein the insulating film is a silicon oxide film.   The electrostatic actuator according to claim 4, wherein the insulating film is made of a dielectric material having a relative dielectric constant higher than that of silicon oxide. As a dielectric material having a relative dielectric constant higher than that of silicon oxide, at least one of aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), hafnium nitride silicate (HfSiN), and hafnium oxynitride silicate (HfSiON) is used. The electrostatic actuator according to claim 9, wherein the electrostatic actuator is selected. An electrostatic device comprising: a fixed electrode formed on a glass substrate; and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween, wherein the opposing surface of the fixed electrode is formed in a stepped multistage structure. In the manufacturing method of the actuator,
Forming a recess in the glass substrate and forming a bottom surface of the recess in a stepped multi-stage structure;
Forming the fixed electrode on the bottom surface of the recess;
Forming an insulating film on the fixed electrode;
Two types of surface protective films having different physical properties are formed on the insulating film, and the surface protective film is selectively removed by patterning and etching, so that the uppermost layer has the highest hardness and the lowermost layer A surface protective film having the highest volume resistivity,
A method for manufacturing an electrostatic actuator, comprising: An electrostatic device comprising: a fixed electrode formed on a glass substrate; and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween, wherein the opposing surface of the fixed electrode is formed in a stepped multistage structure. In the manufacturing method of the actuator,
Forming a recess in the glass substrate and forming the fixed electrode on a bottom surface of the recess;
Forming an insulating film on the fixed electrode, and forming the insulating film in a stepped multi-stage structure;
Two types of surface protective films having different physical properties are formed on the insulating film, and the surface protective film is selectively removed by patterning and etching, so that the uppermost layer has the highest hardness and the lowermost layer A surface protective film having the highest volume resistivity,
A method for manufacturing an electrostatic actuator, comprising: An electrostatic device comprising: a fixed electrode formed on a glass substrate; and a movable electrode disposed to face the fixed electrode with a predetermined gap therebetween, wherein the opposing surface of the fixed electrode is formed in a stepped multistage structure. In the manufacturing method of the actuator,
Forming a recess in the glass substrate and forming the fixed electrode on a bottom surface of the recess;
Forming an insulating film on the fixed electrode;
Two types of surface protective films having different physical properties are formed on the insulating film, and the surface protective film is selectively removed by patterning and etching, so that the uppermost layer has the highest hardness and the lowermost layer Forming a step-like multistage structure with a surface protective film having the highest volume resistivity,
A method for manufacturing an electrostatic actuator, comprising:   The surface protective film is formed by an RF-CVD method, and two types of surface protective films having different physical properties are formed by changing an RF output during film formation or during film formation. A method for manufacturing an electrostatic actuator according to claim 11.   A droplet discharge head comprising the electrostatic actuator according to claim 1.   15. A method of manufacturing a droplet discharge head, wherein the method of manufacturing an electrostatic actuator according to claim 11 is applied to manufacture a droplet discharge head.   A liquid droplet ejection apparatus comprising the liquid droplet ejection head according to claim 15.

Images