JP5515382B2 - Electrostatic actuator, droplet discharge head, and manufacturing method thereof - Google Patents

Description

  The present invention relates to an electrostatic drive type electrostatic actuator, a droplet discharge head, and a manufacturing method thereof.

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 representative 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, the vibration plate formed in the ink flow path is vibrated by electrostatic force, whereby ink droplets are ejected and landed on the recording paper from the nozzle holes to perform printing or the like.

In recent years, there has been an increasing demand for higher quality and higher definition of printing, image quality, and the like for inkjet heads. For this reason, nozzle diameters are becoming increasingly smaller, and electrostatic actuators are also becoming smaller. Therefore, in the ink jet head having such a minute diameter nozzle hole, it is necessary to increase the driving voltage of the electrostatic actuator in order to enable ejection of ink droplets. On the other hand, since the diaphragm repeatedly contacts and separates from the individual electrodes, it is required to improve the driving durability of the electrostatic actuator and the pressure generated by the actuator. In order to meet these requirements, the present applicant has proposed an electrostatic actuator in which a diamond-like carbon (hereinafter referred to as DLC) film is formed on one or both contact surfaces of the diaphragm and the individual electrodes (for example, , See Patent Document 1).
Further, paying attention to the stress characteristics of the DLC film, an electrostatic actuator in which a tensile stress film such as a DLC film is formed on a compressive stress film has been proposed as a means for realizing an electrostatic actuator with high driving ability ( For example, see Patent Document 2).

JP 2008-18706 A JP 2008-99364 A

  Although the DLC film generally has excellent lubrication characteristics, the film stress is large and there is a problem in the adhesion with the base film. Therefore, when the DLC film is used as a sliding member, the DLC film is in close contact with the base film. From the viewpoint of ensuring the safety, it is desirable that the film stress is small. Therefore, in the electrostatic actuator shown in Patent Document 1, a silicon oxide film is used as a base film for the DLC film. However, it has been found that the DLC film has the following problems.

When applying a DLC film to an electrostatic actuator, the electrostatic actuator is brought into contact with and released from the electrostatic force, so that the electrostatic actuator is charged by the contact and release, and this phenomenon occurs particularly when the drive voltage increases. Appeared and the vibration plate was stuck, resulting in failure to drive. Here, the adhesion of the diaphragm means that the diaphragm remains adhered to the individual electrode even if the drive voltage is canceled mainly due to residual charges generated in the diaphragm and the individual electrode (phenomenon). .
For example, in an electrostatic actuator in which a silicon oxide film is formed on the contact surface of one electrode, a silicon oxide film is formed on the contact surface side of the other electrode, and a hydrogenated amorphous carbon film (a kind of DLC film) is formed thereon. When the driving voltage was increased to 30 V, for example 70 V, which was higher than the conventional 30 to 40 V, the sticking of the diaphragm occurred.

  The above phenomenon is considered to be caused by charging of the hydrogenated amorphous carbon film, and a correlation is observed with the insulating film physical properties of the contact surface, specifically, the volume resistivity of the contact surface insulating film. According to the study by the present inventors, when a DLC film having a high volume resistivity is formed on the contact surface, it is difficult for the vibration plate to stick to the high voltage drive as the volume resistivity increases. all right. Here, the volume resistivity of the insulating film refers to an electrical resistance value per unit volume, and is the same concept as the electrical resistivity in the case of a conductor.

As a method for increasing the volume resistivity of the hydrogenated amorphous carbon film, there is a method in which the carbon bonding state is a film having many sp3 bonds.
However, if the sp3 bond component is large, the friction coefficient tends to be high, the lubricity of the DLC film is lowered, and the SiO ₂ film on the diaphragm side becomes a foreign substance (a part of the SiO ₂ film is peeled off to become a foreign substance) As a result, another problem arises in that the ink discharge characteristics are deteriorated in a durable manner.

  Another method for increasing the volume resistivity is to increase the amount of hydrogen in the film. That is, it is a method of forming a DLC film while lowering the RF output during the formation of the DLC film and suppressing the decomposition of the source gas. In this case, there are few electrical defects and a large amount of hydrogen in the film. A membrane is obtained. Here, the amount of hydrogen in the DLC film simply means the hydrogen content in the DLC film. To be precise, when the molecular formula is CxHy, it is expressed by the ratio of the number of atoms of y / (x + y). ERDA (Elastic Recoil Detection Analysis) etc. are used for the analysis method of the amount of hydrogen in the film.

  However, in this method, recombination of carbon atoms from the source gas to the DLC film is difficult to occur, and the hardness of the DLC film becomes soft. Therefore, when the number of operations of the electrostatic actuator increases, Is likely to occur, and there is a problem in that the ink ejection characteristics are deteriorated in a durable manner.

  The present invention has been made on the basis of the above-mentioned knowledge, prevents sticking of the diaphragm, prevents the contact surface side insulating film or DLC film from becoming a foreign substance, and has excellent driving durability. It is an object of the present invention to provide an electrostatic actuator capable of being driven at a high voltage, a droplet discharge head, a manufacturing method thereof, 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 that is disposed to face the fixed electrode at a predetermined interval and is displaced by an electrostatic force generated between the fixed electrode and the fixed electrode. In the electrostatic actuator, an oxide insulating film and a hydrogenated amorphous carbon film are formed on at least one of the movable electrode and the fixed electrode, and a sealed space related to the opposing arrangement of the movable electrode and the fixed electrode is formed in an organic system. The atmosphere is related to the treatment agent.
According to the present invention, since the sealed space related to the opposed arrangement of the movable electrode and the fixed electrode is set to the atmosphere related to the organic processing agent, when the movable electrode comes into contact with the fixed electrode in the atmosphere, The hydrogenated amorphous material that forms the outermost film of at least one of the movable electrode and the fixed electrode by reducing the contact area so that the movable electrode and the fixed electrode are not too closely contacted with each other. Contact charging in the carbon film can be suppressed. For this reason, for example, even if high voltage driving is performed, sticking between the movable electrode and the fixed electrode can be prevented, and an electrostatic actuator capable of maintaining driving characteristics and extending the life can be manufactured.

In the electrostatic actuator according to the present invention, the hydrogenated amorphous carbon film is formed on an insulating film formed on at least one of the movable electrode and the fixed electrode.
According to the present invention, since the insulating film is formed on at least one of the movable electrode and the fixed electrode, it is possible to prevent dielectric breakdown or the like that may occur between the fixed electrode and the movable electrode, and to extend the life.

The insulating film of the electrostatic actuator according to the present invention is an oxide insulating film.
According to the present invention, since the insulating film is an oxide insulating film, adhesion with the hydrogenated amorphous carbon film can be ensured.

The oxide insulating film of the electrostatic actuator according to the present invention is a silicon oxide film.
According to the present invention, since the silicon oxide film is an oxide insulating film, it is possible to further ensure adhesion with the hydrogenated amorphous carbon film.

In the electrostatic actuator according to the present invention, the hydrogenated amorphous carbon film is formed on both the movable electrode and the fixed electrode.
According to the present invention, the hydrogenated amorphous carbon film is formed on both the movable electrode and the fixed electrode, and the same kind of contact is made, so that no foreign matter is generated by the contact and the drive characteristics are maintained. Can do.

In the electrostatic actuator according to the present invention, the organic treating agent includes an organic compound having a dimethylsilylalkyl group or a trimethylsilylalkyl group.
According to this invention, sticking can be prevented by making sealed space into the atmosphere of the organic type processing agent containing the organic compound which has a dimethylsilylalkyl group or a trimethylsilylalkyl group.

In addition, the method for manufacturing an electrostatic actuator according to the present invention is arranged so that the fixed electrode formed on the substrate is opposed to the fixed electrode at a predetermined interval and is displaced by the electrostatic force generated between the fixed electrode. In a method of manufacturing an electrostatic actuator comprising a movable electrode, a step of forming an oxide-based insulating film on one or both opposing surfaces of the movable electrode and the fixed electrode; A step of forming a carbon film, a step of fixing the fixed electrode and the movable electrode so as to face each other at a predetermined interval, and a step of removing moisture in a space formed by arranging the movable electrode and the fixed electrode to face each other. And a step of sealing the space by introducing an organic processing agent into the space and performing a gas phase treatment.
According to the present invention, in the space related to the opposed arrangement of the movable electrode and the fixed electrode, after removing the water, it is sealed as an atmosphere related to the organic processing agent, so when driving the electrostatic actuator, When the organic compound in the atmosphere is brought into contact with the fixed electrode, the contact area is reduced so that the movable electrode does not come into close contact with the fixed electrode, thereby forming hydrogen as a film on the outermost surface of at least one of the movable electrode and the fixed electrode. Contact charging in the hydrogenated amorphous carbon film can be suppressed. For this reason, for example, even when high voltage driving is performed, it is possible to manufacture an electrostatic actuator that can prevent sticking between the movable electrode and the fixed electrode, maintain drive characteristics, and achieve a long life.

Moreover, the manufacturing method of the electrostatic actuator which concerns on this invention performs a gaseous-phase process using the organic type processing agent containing the organic compound which has a dimethylsilylalkyl group or a trimethylsilylalkyl group.
According to the present invention, the sealed space is made in a gas phase with a bulky substituent capable of further reducing the contact area, specifically, an organic treatment agent containing an organic compound having a dimethylsilylalkyl group or a trimethylsilylalkyl group. Since the processing is performed, sticking due to driving can be prevented.

Moreover, the manufacturing method of the electrostatic actuator which concerns on this invention sets the substrate temperature when forming a hydrogenated amorphous carbon film to 300 degrees C or less.
According to the present invention, when the hydrogenated amorphous carbon film is formed, the substrate temperature is set to 300 ° C. or lower, so that a hydrogenated amorphous carbon film having a low friction coefficient can be formed. For this reason, the electrostatic actuator which can improve the durability in contact, etc., can maintain drive characteristics, and can achieve a long life can be manufactured.

Moreover, the manufacturing method of the electrostatic actuator which concerns on this invention makes RF output 300W or less when forming a hydrogenated amorphous carbon film.
According to the present invention, since the RF output when forming the hydrogenated amorphous carbon film is set to 300 W or less, the film containing hydrogen in the hydrogenated amorphous carbon film can be formed by suppressing the decomposition of the source gas. By increasing the volume and increasing the volume resistivity, it is possible to form a hydrogenated amorphous carbon film that is difficult to be charged.

A droplet discharge head according to the present invention is equipped with the electrostatic actuator described above.
According to the present invention, by setting the sealed space related to the opposing arrangement of the movable electrode and the fixed electrode as an atmosphere related to the organic processing agent, it is possible to discharge liquid droplets having long-term driving durability and capable of high-voltage driving. You can get a head.

Further, the manufacturing method of the droplet discharge head according to the present invention applies the above-described manufacturing method of the electrostatic actuator.
According to the present invention, the space related to the opposing arrangement of the movable electrode and the fixed electrode is sealed as an atmosphere related to the organic processing agent, thereby having a long-term driving durability and capable of high voltage driving. A discharge head can be manufactured.

1 is an exploded perspective view showing a schematic configuration of a droplet discharge head according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing a schematic configuration of the droplet discharge head of FIG. 1 in an assembled state. FIG. 3 is a top view of the droplet discharge head of FIG. 2. The AA expanded sectional view of FIG. FIG. 5 is a schematic cross-sectional view of a droplet discharge head according to Embodiment 2 of the present invention. BB expanded sectional view of FIG. FIG. 6 is a schematic cross-sectional view of a droplet discharge head according to Embodiment 3 of the present invention. CC expanded sectional view of FIG. FIG. 4 is a schematic cross-sectional view of the manufacturing process of the electrode substrate of the droplet discharge head according to the first embodiment. FIG. 3 is a schematic cross-sectional view of a manufacturing process of the droplet discharge head according to the first embodiment. FIG. 6 is a schematic cross-sectional view of a manufacturing process of a droplet discharge head according to Embodiment 2. FIG. 12 is a schematic cross-sectional view of the manufacturing process following FIG. 11. 1 is a schematic perspective view showing an ink jet printer to which a droplet discharge head is applied.

  Embodiments of a droplet discharge head including an electrostatic actuator to which the present invention is applied will be described below with reference to the drawings. Here, as an example of a droplet discharge head, a face discharge type electrostatic drive type droplet discharge head that discharges ink droplets from nozzle holes provided on the surface of a nozzle substrate will be described with reference to FIGS. explain. 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 a droplet discharge 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 droplet discharge head showing a schematic configuration of the substantially right half of FIG. 1 in the assembled state, FIG. 3 is a top view of the droplet discharge head of FIG. 2, and FIG. 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 droplet discharge head 10 according to the first embodiment is independent of the nozzle substrate 1 in which a plurality of nozzle holes 11 are provided at a predetermined pitch and the nozzle holes 11. The cavity substrate 2 provided with the ink supply path is bonded to the electrode substrate 3 provided with the individual electrodes 5 facing the diaphragm 6 provided on the cavity substrate 2. .

  As shown in FIGS. 2 and 4, the electrostatic actuator 4 provided for each nozzle hole 11 of the droplet discharge head 10 is an individual electrode 5 formed in the recess 32 of the electrode substrate 3 made of glass as a fixed electrode. And a diaphragm 6 that is configured by a bottom wall of the discharge chamber 21 of the cavity substrate 2 made of silicon as a movable electrode and is arranged to face the individual electrode 5 with a predetermined gap (gap) G interposed therebetween. .

Here, on the individual electrode 5, for example, a silicon oxide film (SiO ₂ film) is formed as the oxide insulating film 7. Further, a DLC film is formed on the oxide insulating film 7. Here, it is assumed that a hydrogenated amorphous carbon film (hereinafter referred to as an ac: H film) 8 is formed as the DLC film. For this reason, it is the ac-H film 8 that actually contacts the diaphragm 6. Here, the ac-H film 8 has a high volume resistivity in order to eliminate charging as much as possible.

  On the other hand, in order to prevent dielectric breakdown or short circuit of the electrostatic actuator 4 on the contact surface side of the diaphragm 6, that is, the entire joint surface of the cavity substrate 2 where the electrode substrate 3 is joined, for example, thermal oxidation of silicon is performed. An insulating film 9 made of a film is formed.

  Further, here, after the gap G formed by disposing the individual electrode 5 and the diaphragm 6 to face each other is dehydrated by removing moisture, a gas phase treatment is performed with an organic treatment agent, and an atmosphere ( (Hereinafter referred to as an organic treating agent atmosphere). By filling the gap G with the organic processing agent atmosphere, for example, when the organic compound constituting the organic processing agent is brought into contact with the individual electrode 5 of the vibration plate 6 (insulating film 9), it is individually separated from the vibration plate 6. The contact area is reduced by entering between the electrodes 5 and inhibiting the close contact with the ac: H film 8. For this reason, the contact charging in the ac: H film 8 can be suppressed, and for example, the vibration plate 6 can be prevented from sticking even when high voltage driving is performed. Further, for example, when the oxide insulating film 7 is exposed, the adhesion of the diaphragm 6 can be prevented by forming a hydrophobic film on the surface of the oxide insulating film 7 by treatment with an organic treatment agent. Can do.

When performing vapor phase processing, if the processing atmosphere contains a slight amount of moisture, the moisture may be charged and sticking may occur. Process. The organic processing agent is a processing agent having a bulky substituent capable of further reducing the contact area, specifically, a dimethylsilylalkyl group or a trimethylsilylalkyl group. Here, it is desirable to use an organic compound having a boiling point of about 100 ° C. and a certain vapor pressure at room temperature, particularly from the viewpoint of making the elongated gap uniform in the atmosphere of the organic processing agent. Specifically, as a treating agent having a trimethylsilylalkyl group, HMDS (hexamethyldisilazane (CH ₃ ) ₃ SiNHSi (CH ₃ ) ₃ ), trimethyl-normal propoxysilane (C ₃ H ₇ O—Si (CH ₃ ) ₃ ) Etc. are desirable. In the present invention, HMDS is used.

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 of IZO (Indium Zinc Oxide) or a metal such as Au or Al may be used.
A drive control circuit such as a driver IC is used as a drive means for the electrostatic actuator 4 as shown in FIG. 4 in a simplified manner in the terminal portion 5a of the individual electrode 5 and the common electrode 26 provided on the cavity substrate 2. 40 is connected by wiring through the FPC.

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 (on the side of the bonding surface with the cavity substrate 2).
In addition, the nozzle substrate 1 is formed with an orifice 12 communicating the discharge chamber 21 and the reservoir 23 of the cavity substrate 2 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 single crystal silicon substrate having a (110) plane orientation. In the cavity substrate 2, a recess 22 that becomes a discharge chamber 21 provided in the ink flow path and a recess 24 that becomes a reservoir 23 are formed by etching. A plurality of the 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 recess 22 constitutes a discharge chamber 21 and communicates with each nozzle hole 11 and is an orifice 12 that is 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, 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 problems such as peeling.

  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 thereto, whereby the main body of the droplet discharge head 10 is completed as shown in FIG. To do. Thereafter, the drive control circuit 40 is wired to each individual electrode 5 and the common electrode 26 using FPC. Furthermore, the electrode lead-out portion (also referred to as FRP mounting portion) 34 is hermetically sealed by applying a sealing material 35 such as an epoxy resin to the external communication portion of the electrostatic actuator 4. Thereby, it is possible to reliably prevent moisture, foreign matter and the like from entering the gap of the electrostatic actuator 4, and the reliability of the droplet discharge head 10 is improved.

Here, the operation of the droplet discharge head 10 will be described. In order to eject ink droplets from an arbitrary nozzle hole 11, the electrostatic actuator 4 corresponding to the nozzle hole 11 is driven as follows.
A pulse voltage is applied between the individual electrode 5 and the diaphragm 6 which is a common electrode by the drive control circuit 40. The diaphragm 6 is attracted and brought into contact with the individual electrode 5 side by the electrostatic force generated by the application of the pulse voltage, a negative pressure is generated in the discharge chamber 21, the ink in the reservoir 23 is sucked, and the ink vibration (meniscus) Vibration). When the voltage is released when the vibration of the ink becomes substantially maximum, the vibration plate 6 is detached from the individual electrode 5, and the ink is pushed out from the nozzle hole 11 by the restoring force of the vibration plate 6 at that time. Is discharged.

The electrostatic actuator 4 of the present embodiment is driven at a high voltage by forming a silicon oxide film as the oxide-based insulating film 7 on the individual electrode 5 and forming an ac: H film 8 which is a DLC film. Charging is unlikely to occur even if Therefore, sticking of the diaphragm 6 can be prevented, and high voltage driving is possible.
Further, since the gap G due to the opposing arrangement of the individual electrode 5 and the diaphragm 6 is an organic processing agent atmosphere, the contact area between the ac: H film 8 and the diaphragm 6 can be reduced at the time of contact. A-c: Contact charging in the H film 8 can be suppressed, and for example, even when high voltage driving is performed, the vibration plate 6 can be prevented from sticking.
Further, by reducing the friction coefficient of the ac: H film 8, it is possible to prevent the occurrence of foreign matter due to contact between the ac: H film 8 and the insulating film 9 on the diaphragm 6 side.
Therefore, according to the present embodiment, it is possible to realize the electrostatic actuator 4 that can be driven at a high voltage and has long-term driving durability.

In the present embodiment, the oxide insulating film 7 on the individual electrode 5 is a silicon oxide film, but a so-called High-k material such as Al ₂ O ₃ or HfO ₂ may also be used. . Since the high-k material has a relative dielectric constant larger than that of SiO ₂ , the pressure generated by the actuator can be increased, which contributes to high-voltage driving and further increases in density.

Embodiment 2. FIG.
5 is a schematic cross-sectional view of a droplet discharge head according to Embodiment 2 of the present invention, and FIG. 6 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, the ac: H film 8 shown in the first embodiment is formed on the diaphragm 6 side. For this reason, a silicon thermal oxide film to be the oxide insulating film 7 is formed on the entire bonding surface side of the diaphragm 6 by a thermal oxidation method. Then, an ac: H film 8 is formed on the silicon thermal oxide film as in the first embodiment. Since anodic bonding cannot be performed when DLC is formed on the entire surface of the cavity substrate 2, the ac: H film 8 is formed only on the vibration plate 6 portion facing the individual electrode 5.
On the other hand, an insulating film 9 made of a silicon oxide film is formed on the individual electrode 5 in order to prevent dielectric breakdown or short circuit.
Then, the gap G due to the opposing arrangement of the individual electrode 5 and the diaphragm 6 is filled with an HDMS atmosphere which is an organic processing agent, and contact charging in the ac: H film 8 is suppressed.

Also in the configuration of the second embodiment, the gap G is filled with the organic processing agent atmosphere as in the first embodiment. Therefore, contact charging in the ac: H film 8 is suppressed, and the diaphragm 6 Sticking can be prevented. In addition, the electrostatic actuator 4 can be prevented from becoming a foreign substance due to contact between the insulating film 9 on the contact surface side and the DLC film (ac: H film 8), and can be driven at a high voltage and has long-term driving durability. can do.
In the case of the second embodiment, the rigidity of the diaphragm 6 can be increased as compared with the first embodiment. Therefore, when applied to the droplet discharge head 10, the discharge pressure and the discharge speed (printing speed, etc.) are improved. Contribute to.

Embodiment 3 FIG.
7 is a schematic cross-sectional view of a droplet discharge head according to Embodiment 3 of the present invention, and FIG. 8 is an enlarged cross-sectional view taken along the line CC of FIG.
The electrostatic actuator 4 according to the third embodiment has a configuration in which the first embodiment and the second embodiment are combined. In this case, both the individual electrode 5 and the diaphragm 6 are in contact with and separated from the ac: H film, which is a DLC film, so that no foreign matter is generated.
Therefore, also in the third embodiment, since the gap G is filled with the organic processing agent atmosphere, contact charging in the ac: H film 8 can be suppressed and sticking of the diaphragm 6 can be prevented. The electrostatic actuator 4 that can be driven by voltage and has long-term driving durability can be realized.

(Method for manufacturing droplet discharge head)
Next, an example of a method for manufacturing the droplet discharge head 10 according to Embodiments 1 to 3 will be described with reference to FIGS.

In the case of the first embodiment (see FIGS. 9 and 10)
FIG. 9 is a partial cross-sectional view showing a manufacturing process of the electrode substrate of the droplet discharge head 10 according to the first embodiment, in which a part of a plurality of wafer substrates formed on the wafer-like glass substrate is shown in cross section. is there. FIG. 10 is a partial cross-sectional view of a manufacturing process of the droplet discharge head 10 according to the first embodiment, and shows a cross section of a part of the silicon wafer. The numerical values of the substrate thickness, film thickness, etching depth, temperature, pressure, and the like described below are just examples, and are not limited thereto.

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. Note that the recess 32 has a groove shape slightly larger than the shape of the individual electrode 5, and a plurality of the recesses 32 are formed for each individual electrode 5.
Then, for example, an ITO (Indium Tin Oxide) film having a thickness of 100 nm is formed by sputtering, and this ITO film is patterned by photolithography to remove the portions other than the individual electrode 5 by etching to remove the inside of the recess 32. The individual electrode 5 is formed on the substrate (FIG. 9A).

(B) Next, as the insulating film 7 on the individual electrode 5, RF-CVD (Chemical Vapor Deposition) using TEOS (Tetraethoxysilane) as a raw material gas on the entire surface of the glass substrate 300 on the bonding surface side. A SiO ₂ film is formed with a thickness of 30 nm by a method (hereinafter referred to as TEOS-CVD method) (FIG. 9B).

(C) Next, a film to be an ac: H film 8 is formed on the entire surface of the SiO ₂ film by RF-CVD using toluene as a source gas (FIG. 9C). At this time, film formation is performed with RF power (high frequency output): 300 W, raw material gas flow rate: 5 sccm, and nitrogen gas (dilution gas) flow rate: 5 sccm.

(D) Next, in order to perform bonding by anodic bonding, the ac: H film 8 is left only on the electrode portion of the individual electrode 5. For this reason, a resist is applied to the portion to become the ac: H film 8, and patterning is performed by photolithography. Then, after forming the resist pattern, only the ac: H film 8 is left, and the other portions of the film are removed by O ₂ ashing. Next, the SiO ₂ film of the bonding portion 36 and the FPC mounting portion 34 (the terminal portion 5a of the individual electrode 5) is removed by RIE (Reactive Ion Etching) dry etching using CHF ₃ gas (FIG. 9D). Thereafter, a hole 33a to be the ink supply hole 33 is formed in the glass substrate 300 by blasting or the like.

  Next, a method for manufacturing the droplet discharge head 10 according to Embodiment 1 will be described with reference to FIG. 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, an SiO ₂ film having a thickness of 110 nm is formed as an insulating film 9 by a thermal oxidation method (FIG. 10A).

(B) Next, the silicon substrate 200 is aligned on the electrode glass substrate 300A and anodic bonded (FIG. 10B).
(C) Next, the entire surface of the bonded silicon substrate 200 is polished to reduce the thickness to, for example, about 50 μm (FIG. 10C), 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 a discharge chamber 21 having the diaphragm 6 as a bottom wall, a recess 24 serving as a reservoir 23, and a recess 27 serving as an FPC mounting part (electrode extraction part) 34 are formed (FIG. 10D). . 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 recess 27 is removed by RIE (Reactive Ion Etching) dry etching using CHF ₃ gas to open the FPC mounting portion (electrode extraction portion) 34 (FIG. 10E). Thereafter, water adhering to the inside of the electrostatic actuator 4 is removed. Moisture removal is performed under reduced pressure by placing the bonded silicon substrate 200 in, for example, a vacuum chamber and heating and vacuuming. At this time, heating is performed so that the temperature of the bonded silicon substrate 200 is 300 ° C. or lower (so as not to exceed 300 ° C.). This is because the temperature at which the physical properties of the ac: H film 8 (DLC film) can be maintained without being changed is generally about 350 ° C. or lower. By heating so as not to exceed 300 ° C., the physical properties are not changed.
(F) Then, after the required time has elapsed, HMDS, which is an organic processing agent, is introduced, and a vapor phase process is performed in which the bonded substrate is left in a HMDS atmosphere for a predetermined time. Furthermore, for example, in an atmosphere of an organic processing agent, a sealing material 35 such as an epoxy resin is applied to the external communication portion (opening portion) of the gap to perform hermetic sealing (FIG. 10F). Here, by exposing to the organic processing agent atmosphere, the substance related to the organic processing agent does not affect the discharge characteristics by adsorbing to the recesses which become the discharge chamber 21 and the reservoir 23. It is desirable to remove by performing RCA cleaning or the like.
Further, the ink supply hole 33 is formed by penetrating the bottom of the recess 24 by microblasting or the like. Further, in order to prevent corrosion of the ink flow path groove, an ink protective film (not shown) made of a SiO ₂ film is formed on the surface of the silicon substrate by the TEOS-CVD method. 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 formed in advance is bonded onto the surface of the cavity substrate 2 by adhesion. Finally, if the individual head chips are cut by dicing, the main body of the droplet discharge head 10 described above is completed (FIG. 10G).

In the manufacturing method of the droplet discharge head 10 according to the first embodiment, the gas phase treatment is performed while being left in the organic processing agent atmosphere, and the gap G is changed to the organic processing agent atmosphere. The contact area between the a-c: H film 8 and the diaphragm 6 can be reduced, and contact charging in the a-c: H film 8 can be suppressed by a simpler process. 6 can be prevented.
Further, since the cavity substrate 2 is manufactured from the silicon substrate 200 bonded to the electrode glass substrate 300A prepared in advance, the silicon substrate 200 is supported by the electrode glass substrate 300A, and the silicon substrate 200 is thinned. However, it does not crack or chip, and handling becomes easy. Therefore, the yield is improved as compared with the case where the cavity substrate 2 is manufactured alone.

In the case of Embodiment 2 (see FIGS. 11 and 12)
A method for manufacturing the droplet discharge head 10 according to the second embodiment will be described with reference to FIGS. However, although the manufacturing process of the electrode glass substrate 300B is not illustrated, after the steps (a) and (b) in FIG. 9, FPC is performed by RIE (Reactive Ion Etching) dry etching using CHF ₃ gas. If the mounting portion 34 (terminal portion 5a of the individual electrode 5) and the SiO ₂ film at the joint portion 36 are removed, the electrode glass substrate 300B according to the second embodiment can be manufactured.

(A) In the case of the second embodiment, as in FIG. 10A, first, silicon 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 a silicon substrate 200 having a thickness of 280 μm. A substrate 200 is manufactured, and an SiO ₂ film having a thickness of 110 nm is formed as an oxide insulating film 7 by thermal oxidation. Next, a film to be an ac: H film 8 is formed on the entire surface of the SiO ₂ film of the boron diffusion layer 201 by RF-CVD using toluene as a source gas (FIG. 9C). Also in this case, film formation is performed with RF power (high frequency output): 300 W, raw material gas flow rate: 5 sccm, and nitrogen gas (dilution gas) flow rate: 5 sccm.

(B) Next, in order to be able to perform anodic bonding, the ac: H film 8 is left only in the portion that becomes the diaphragm 6. For this reason, a resist is applied to the portion to become the ac: H film 8, and patterning is performed by photolithography. Then, after forming the resist pattern, only the ac: H film 8 is left, and the other part of the film is removed by O ₂ ashing (FIG. 11B).

(C) The silicon substrate 200 thus formed is aligned and anodic bonded on the electrode glass substrate 300B that has been prepared in a separate process (FIG. 11C).
Thereafter, similarly to FIGS. 10C to 10G, the silicon substrate 200 is thinned (FIG. 11D), and ink channel grooves are formed by anisotropic wet etching (FIG. 11E). ), An opening by dry etching of the FPC mounting portion 34 (FIG. 11 (f)), formation of a sealing portion by the common electrode 26 and the sealing material 35, and penetration formation of the ink supply hole 33 (FIG. 11 (g)). After that, by cutting into individual head chips by dicing, the main body portion of the droplet discharge head 10 of Embodiment 2 is completed (FIG. 11 (h)).

  In the method for manufacturing the droplet discharge head 10 according to the second embodiment, the same effect as in the first embodiment can be obtained.

In the case of the third embodiment Although the illustration of the manufacturing method of the droplet discharge head 10 according to the third embodiment is omitted, as apparent from the above description, the electrode glass substrate 300B of FIGS. Then, the electrode glass substrate 300A in FIG. 9 may be used.
In the case of the third embodiment, the manufacturing cost is slightly increased as compared with the first and second embodiments, but the droplet discharge head 10 in which the insulating film is not made a foreign substance can be manufactured.

  In the above embodiment, the electrostatic actuator, the droplet discharge head, and the manufacturing method thereof have been described. However, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the idea of the present invention. Can be changed. 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 holes, for example, in addition to the ink jet printer 400 as shown in FIG. 13, the manufacture of color filters for liquid crystal displays, the formation of light emitting portions of organic EL display devices, genetic testing, 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 oxide-based insulating film, 8 hydrogenated amorphous carbon film (a- c: H film), 9 insulating film, 10 droplet discharge head, 11 nozzle hole, 12 orifice, 13 diaphragm section, 21 discharge chamber, 23 reservoir, 26 common electrode, 32 recess, 33 ink supply hole, 34 electrode takeout section (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 (12)

A fixed electrode formed on a substrate; and a movable electrode disposed opposite to the fixed electrode at a predetermined interval and displaced by a potential difference with the fixed electrode, wherein the fixed electrode and the movable electrode are in contact with each other In the electrostatic actuator that detaches
At least one of the movable electrode and the fixed electrode has a hydrogenated amorphous carbon film,
The sealed space between the movable electrode and the fixed electrode is an atmosphere of an organic processing agent,
An electrostatic actuator, wherein a maximum value of the potential difference is greater than 40V.   The electrostatic actuator according to claim 1, wherein the hydrogenated amorphous carbon film is formed on an insulating film formed on at least one of the movable electrode and the fixed electrode.   The electrostatic actuator according to claim 2, wherein the insulating film is an oxide-based insulating film.   4. The electrostatic actuator according to claim 3, wherein the oxide insulating film is a silicon oxide film.   The electrostatic actuator according to claim 1, wherein the hydrogenated amorphous carbon film is formed on both the movable electrode and the fixed electrode.   The electrostatic actuator according to claim 1, wherein the organic processing agent contains an organic compound having a dimethylsilylalkyl group or a trimethylsilylalkyl group. A fixed electrode formed on a substrate; and a movable electrode disposed opposite to the fixed electrode at a predetermined interval and displaced by a potential difference with the fixed electrode, wherein the fixed electrode and the movable electrode are in contact with each other In the manufacturing method of the electrostatic actuator that performs detachment ,
Forming an oxide-based insulating film on one or both opposing surfaces of the movable electrode and the fixed electrode;
Forming a hydrogenated amorphous carbon film on the oxide insulating film;
Fixing the fixed electrode and the movable electrode so as to face each other at the predetermined interval;
Removing moisture in a space formed by arranging the movable electrode and the fixed electrode to face each other;
A process of introducing an organic processing agent into the space to perform a gas phase treatment, and sealing the space;
The method of manufacturing an electrostatic actuator, wherein a maximum value of the potential difference is larger than 40V.   8. The method of manufacturing an electrostatic actuator according to claim 7, wherein the vapor phase treatment is performed using the organic processing agent containing an organic compound having a dimethylsilylalkyl group or a trimethylsilylalkyl group.   The method for manufacturing an electrostatic actuator according to claim 7 or 8, wherein a substrate temperature when forming the hydrogenated amorphous carbon film is 300 ° C or lower.   10. The method of manufacturing an electrostatic actuator according to claim 7, wherein an RF output when forming the hydrogenated amorphous carbon film is 300 W or less.   A droplet discharge head comprising the electrostatic actuator according to claim 1.   11. A method for manufacturing a droplet discharge head, wherein the method for manufacturing an electrostatic actuator according to claim 7 is applied to manufacture a droplet discharge head.

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