JP2008125327A - Electrostatic actuator, liquid drop discharge head and manufacturing method therefor, and liquid drop discharge apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic actuator capable of improving generated pressure in an actuator, while ensuring required basic characteristics as the electrostatic actuator, and to provide a liquid drop discharge head and a method of manufacturing the electrostatic actuator, and the liquid drop discharge head. <P>SOLUTION: The electrostatic actuator comprises a fixed electrode formed on a substrate; a movable electrode arranged so as to face the fixed electrode via a prescribed gap; a drive means for generating an electrostatic force between the fixed and movable electrodes for generating displacement in the movable electrode; a first insulating film 7 formed on the opposite surface of the fixed electrode; and a second insulating film 8 formed on the facing surface of the movable electrode. In at least one of the first and second insulating films, dielectric materials having relative dielectric constants that are higher than that of a silicon oxide are laminated. <P>COPYRIGHT: (C)2008,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.

  As a droplet discharge head for discharging droplets, for example, an electrostatic drive type inkjet head mounted on an inkjet recording apparatus is known. An electrostatic drive type inkjet head is generally composed of an individual electrode (fixed electrode) formed on a glass substrate, and a diaphragm (movable electrode) disposed opposite to the individual electrode via a predetermined gap. An electrostatic actuator unit is provided. Then, a nozzle substrate in which a plurality of nozzle holes for discharging ink droplets is formed, and an ink flow path such as a discharge chamber and a reservoir that are joined to the nozzle substrate and communicated with the nozzle holes are formed. The cavity substrate is provided, and an electrostatic force is generated in the electrostatic actuator unit so as to apply pressure to the discharge chamber to discharge ink droplets from selected nozzle holes.

In recent years, the demand for higher density and higher speed drive has further increased with the increase in resolution of electrostatic drive type ink jet heads, and electrostatic actuators tend to become increasingly smaller. A conventional electrostatic actuator generally has a structure in which an insulating film made of a silicon oxide (SiO ₂ ) film is formed on a vibration plate, and is anodic bonded to an electrode substrate through the insulating film. However, as a problem of a conventional electrostatic actuator in which a silicon oxide insulating film is provided on a diaphragm, the relative dielectric constant of SiO ₂ is as small as about 3.8. The improvement is limited.

  As means for solving this problem, an electrostatic actuator using an insulating film having a higher relative dielectric constant than silicon oxide, that is, a so-called High-k material (high dielectric constant gate insulating film) as an insulating film has been proposed (for example, Patent Documents). 1). By using such a high dielectric material as an insulating film, the pressure generated by the actuator can be improved.

JP 2006-271183 A

By the way, in order to drive the actuator, it is necessary to apply a voltage between the electrodes. However, if the dielectric strength of the insulating film provided on the electrode is low, the voltage that can be applied to the actuator is limited to a low level from the viewpoint of dielectric strength. Therefore, even in an actuator using a so-called High-k material as an insulating film, it is difficult to improve the generated pressure of the actuator when the dielectric strength of the High-k material is lower than that of silicon oxide. (Because the applied voltage V has to be reduced from the following equation (2)).
As another problem, in the case of an actuator using a high-k material as an insulating film, sufficient bonding strength may not be obtained when the cavity substrate and the electrode substrate are bonded, and the actuator has a sealed structure. Even so, there was a case where the driving durability of the actuator deteriorated due to the penetration of external moisture over a long period of time.

  In view of the above-described problems, the present invention provides an electrostatic actuator, a droplet discharge head, and a manufacturing method thereof that can improve the generated pressure of the actuator while ensuring basic characteristics necessary for the electrostatic actuator. The purpose is to provide.

  In order to solve the above problems, an electrostatic actuator according to the present invention includes a fixed electrode formed on a substrate, a movable electrode disposed to face the fixed electrode with a predetermined gap, the fixed electrode, and the movable electrode. An electrostatic actuator comprising a driving means for generating an electrostatic force between the electrodes and causing displacement of the movable electrode, the first insulating film formed on the opposing surface of the fixed electrode, and the movable electrode And at least one of the first and second insulating films is an insulating film formed by laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide. It is characterized by being.

  According to this configuration, at least one of the first insulating film formed on the fixed electrode side and the second insulating film formed on the movable electrode side is a dielectric material having a relative dielectric constant higher than that of silicon oxide, that is, High. Since the construction is such that the -k materials are laminated, the generated pressure of the actuator can be improved. Further, when the generated pressure of the actuator is set to the same pressure, the thickness of the insulating film can be increased, and an electrostatic actuator having an excellent withstand voltage can be configured.

In the electrostatic actuator of the present invention, the fixed electrode is formed on the glass substrate and the movable electrode is formed on the silicon substrate, and the glass substrate and the silicon substrate are interposed through the silicon oxide film formed on at least one bonding surface. It is what is joined.
According to this configuration, since the glass substrate having the fixed electrode and the silicon substrate having the movable electrode are bonded via the silicon oxide film formed on at least one of the bonding surfaces, a sufficiently high bonding strength can be obtained. .

In the electrostatic actuator of the present invention, the fixed electrode is formed on a glass substrate, the movable electrode is formed on a silicon substrate, and one insulating film formed on the glass substrate and the silicon substrate is oxidized. It is a dielectric material having a relative dielectric constant higher than that of silicon, and the other insulating film is composed of an insulating film formed by laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide.
According to this configuration, both the first insulating film formed on the fixed electrode side and the second insulating film formed on the movable electrode side have a dielectric material having a relative dielectric constant higher than that of silicon oxide, that is, High-k. Since it is a material, the pressure generated by the actuator can be improved. Further, when the generated pressure of the actuator is set to the same pressure, the thickness of the insulating film can be increased, and an electrostatic actuator having an excellent withstand voltage can be configured.

In the electrostatic actuator according to the present invention, the fixed electrode is formed on a glass substrate, the movable electrode is formed on a silicon substrate, and the insulation formed on the outermost surface on the glass substrate and the outermost surface on the silicon substrate. The film is made of the same kind of dielectric material.
According to this configuration, the opposing surface side of each electrode is made of the same type of dielectric material, so stable drive is achieved by eliminating residual charges on the surface of the actuator and the insulating film due to contact charging of the actuator due to contact and release of the actuator. And an electrostatic actuator excellent in driving durability can be configured.

In addition, it is desirable that the insulating film formed by laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide is not provided at the junction between the glass substrate and the silicon substrate.
Since the high-k material insulating film has a difficulty in bonding strength, it is preferable to remove the first insulating film part of the high-k material at the bonding portion of the glass substrate.

As the dielectric material, at least one of aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), hafnium nitride silicate (HfSiN), and hafnium oxynitride silicate (HfSiON) is selected. These materials are dielectric materials having a relative dielectric constant higher than that of silicon oxide, and are excellent in low-temperature film formability, film homogeneity, process adaptability, and the like.

  A first manufacturing method of an electrostatic actuator according to the present invention includes a fixed electrode formed on a substrate, a movable electrode disposed to face the fixed electrode via a predetermined gap, the fixed electrode, and the movable electrode. And a driving means for generating a displacement of the movable electrode by generating an electrostatic force between the first electrode and the second electrode as a first insulating film on the glass substrate on which the fixed electrode is formed. A silicon oxide film as a second insulating film is formed on the entire surface of the bonding surface between the silicon substrate on which the movable electrode is formed and the glass substrate of the silicon substrate on which the movable electrode is formed. A step of forming, a step of removing a portion of the first insulating film in a joint portion between the glass substrate and the silicon substrate, and a step of removing the glass substrate and the silicon substrate from the silicon oxide. A step of anodic bonding through a film, a step of etching the surface opposite to the bonding surface of the silicon substrate to form the movable electrode, and a gap formed between the fixed electrode and the movable electrode. It has the process of removing the moisture which exists inside, and the process of sealing the said gap airtightly, It is characterized by the above-mentioned.

  According to this first manufacturing method, the pressure generated by the actuator can be improved by laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide as the first insulating film on the fixed electrode side. By forming a silicon oxide film over the entire bonding surface of the silicon substrate as the second insulating film on the electrode side, an electrostatic actuator capable of ensuring the necessary bonding strength and withstand voltage 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 substrate, a movable electrode disposed opposite to the fixed electrode with a predetermined gap, the fixed electrode, and the movable electrode. And a driving means for generating a displacement of the movable electrode by generating an electrostatic force between the first electrode and the second electrode as a first insulating film on the glass substrate on which the fixed electrode is formed. And a step of forming a silicon oxide film and a dielectric material having a relative dielectric constant higher than that of silicon oxide as a second insulating film over the entire bonding surface of the silicon substrate on which the movable electrode is formed with the glass substrate. Etching from the surface opposite to the bonding surface of the silicon substrate, the step of laminating, the step of anodic bonding the glass substrate and the silicon substrate through the silicon oxide film, A step of forming a movable electrode, a step of removing moisture present in a gap formed between the fixed electrode and the movable electrode, and a step of hermetically sealing the gap. It is characterized by.

  According to the second manufacturing method, contrary to the first manufacturing method, the dielectric material having a relative dielectric constant higher than that of silicon oxide is stacked as the second insulating film on the movable electrode side of the silicon substrate. Thus, the pressure generated by the actuator can be improved, and the necessary bonding strength and dielectric strength can be ensured by forming the silicon oxide film as the first insulating film on the fixed electrode side. Furthermore, since it is not necessary to remove the first insulating film at the joint portion of the glass substrate, the manufacturing process can be simplified and the electrostatic actuator can be manufactured at a lower cost.

  A third manufacturing method of an electrostatic actuator according to the present invention includes a fixed electrode formed on a substrate, a movable electrode disposed to face the fixed electrode with a predetermined gap, the fixed electrode, and the movable electrode. And a driving means for generating a displacement of the movable electrode by generating an electrostatic force between the first electrode and the second electrode as a first insulating film on the glass substrate on which the fixed electrode is formed. And a step of laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide, and a second insulating film as a second insulating film on the entire surface of the silicon substrate on which the movable electrode is formed, as compared with silicon oxide. A step of forming an insulating film made of a dielectric material having a high relative dielectric constant; a step of removing a portion of the first insulating film at a joint portion between the glass substrate and the silicon substrate; and the glass Formed between the fixed electrode and the movable electrode; a step of anodic bonding the plate and the silicon substrate; a step of etching the surface opposite to the bonding surface of the silicon substrate to form the movable electrode; A step of removing moisture existing in the gap and a step of hermetically sealing the gap.

  According to the third manufacturing method, the dielectric material having a relative dielectric constant higher than that of silicon oxide is laminated as the first insulating film on the fixed electrode side, and the second insulating film on the movable electrode side is more than that of silicon oxide. By forming an insulating film made of a dielectric material having a high relative dielectric constant, an electrostatic actuator in which the pressure generated by the actuator is further improved can be manufactured.

Further, in the first and third manufacturing methods, when the portion of the first insulating film in the bonding portion of the glass substrate is removed, the portion of the first insulating film is patterned and removed by dry etching. Shall.
As a result, the first insulating film portion formed by stacking the high-k materials can be simultaneously and completely removed.

As the dielectric material, at least one selected from aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), hafnium nitride silicate (HfSiN), and hafnium oxynitride silicate (HfSiON) is used for the above reasons. Shall.

  Moreover, it is desirable to seal the gap in a nitrogen atmosphere. Thereby, the high reliability of an electrostatic actuator is securable.

The droplet discharge head according to the present invention includes a nozzle substrate having a single or a plurality of nozzle holes for discharging droplets, and a recess serving as a discharge chamber communicating with each of the nozzle holes between the nozzle substrate and the nozzle substrate. In a liquid droplet ejection head comprising: the formed cavity substrate; and an electrode substrate on which an individual electrode is disposed so as to be opposed to the diaphragm configured at the bottom of the ejection chamber via a predetermined gap. Any one of the electrostatic actuators is provided.
Thereby, a highly reliable droplet discharge head excellent in high-speed driving performance, driving durability, and the like can be provided at low cost.

A method for manufacturing a droplet discharge head according to the present invention includes a nozzle substrate having a single or a plurality of nozzle holes for discharging droplets, and a discharge chamber communicating with each of the nozzle holes between the nozzle substrate and the nozzle substrate. A droplet discharge head comprising: a cavity substrate in which a concave portion is formed; and an electrode substrate on which an individual electrode is disposed so as to be opposed to a diaphragm configured at the bottom of the discharge chamber with a predetermined gap. In the manufacturing method, any one of the above-described electrostatic actuator manufacturing methods is applied.
With this manufacturing method, a highly reliable droplet discharge head excellent in high-speed driving performance, driving durability, and the like can be manufactured at low cost.

  A droplet discharge apparatus according to the present invention includes the above-described droplet discharge head. As a result, a highly reliable droplet discharge device that is excellent in high-speed driving performance, driving durability, and the like can be provided at low cost.

  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 the ink jet head according to the first embodiment, 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, FIG. 3 is an enlarged cross-sectional view of a portion A in FIG. 2, and FIG. 5 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 5, the inkjet head (an example of a droplet discharge head) 10 according to this embodiment includes a nozzle substrate 1 in which a plurality of nozzle holes 11 are provided at a predetermined pitch, and each nozzle hole 11. In contrast, the cavity substrate 2 provided with the ink supply path independently and the electrode substrate 3 provided with the individual electrodes 5 facing the diaphragm 6 provided on the cavity substrate 2 are bonded to each other. Yes.

  As shown in FIG. 2 to FIG. 4, the electrostatic actuator unit 4 provided for each nozzle hole 11 of the inkjet head 10 includes the individual electrode 5 formed in the recess 32 of the glass electrode substrate 3 as a fixed electrode. Each of the individual electrodes 5 includes a diaphragm 6 that is configured as a movable electrode on the bottom wall of the discharge chamber 21 of the cavity substrate 2 made of silicon, and is disposed to face the individual electrode 5 with a predetermined gap G interposed therebetween. A first insulating film 7 is formed on the opposite surface (diaphragm-side opposing surface) of the substrate, and the opposing surface (individual electrode-side opposing surface) of the diaphragm 6, that is, the bonding surface of the cavity substrate 2 bonded to the electrode substrate 3. A second insulating film 8 is formed on the entire surface.

In the electrostatic actuator of the present invention, the insulating film is formed on the opposing surfaces of both the individual electrode 5 and the diaphragm 6, and the first insulating film 7 on the individual electrode 5 side and the second on the diaphragm 6 side. At least one of the insulating films 8 has a laminated structure in which dielectric materials having a relative dielectric constant higher than that of silicon oxide (SiO ₂ ) are laminated. As a dielectric material having a relative dielectric constant higher than that of silicon oxide (SiO ₂ ), that is, a high dielectric material called a high-k material, for example, silicon oxynitride (SiON), aluminum oxide (Al ₂ O ₃ , alumina), oxidation Hafnium (HfO ₂ ), tantalum oxide (Ta ₂ O ₃ ), hafnium nitride silicate (HfSiN), hafnium oxynitride (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), hafnium silicate (HfSiO), zirconium aluminate (ZrAlO), nitrogen-added hafnium aluminate (HfAlON), and composite films thereof Can be mentioned. 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 the first embodiment, the first insulating film 7 on the individual electrode 5 side has a single-layer structure composed of only a silicon oxide film, and the second insulating film 8 on the diaphragm 6 side has an alumina film 8a as the lowermost layer, and the upper layer. The hafnium oxide film 8b has a three-layer structure in which a silicon oxide film 8c is stacked on the outermost surface. With this configuration, the cavity substrate 2 made of silicon and the electrode substrate 3 made of glass can be anodic bonded via the silicon oxide film 8c, so that a sufficiently high bonding strength can be ensured. Regarding the film thickness, the silicon oxide film of the first insulating film 7 is 30 nm, the alumina film 8a of the second insulating film 8 is 30 nm, the hafnium oxide film 8b is 20 nm, and the silicon oxide film 8c is 50 nm. The distance of the gap G is 200 nm, and the thickness of the individual electrode 5 made of ITO (Indium Tin Oxide) is 100 nm.

  2, 3, and 5, the terminal portion 5 a of the individual electrode 5 formed on the electrode substrate 3 and the common electrode formed on the upper surface opposite to the bonding surface of the cavity substrate 2. 26 is connected to a wiring through a flexible wiring board on which a drive control circuit 9 such as a driver IC is mounted as a driving means.

Hereinafter, 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 composed of, for example, two-stage cylindrical nozzle holes having different diameters, that is, an ejection port portion 11a having a smaller diameter and an introduction port portion 11b having a larger diameter. It is configured. The injection port portion 11a and the introduction port portion 11b are provided perpendicular to and coaxially with respect to the substrate surface. The injection port portion 11a has a tip opening on the surface of the nozzle substrate 1, and the introduction port portion 11b is formed on the nozzle substrate 1. Are opened on the back surface (the surface on the bonding side to be bonded to the cavity substrate 2).
The nozzle substrate 1 is formed with an orifice 12 that communicates the discharge chamber 21 of the cavity substrate 2 with the reservoir 23.

  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 ink droplets, there is no scattering of ink droplets, and variations in the ejection amount of ink droplets can be suppressed. In addition, the nozzle density can be increased.

  The cavity substrate 2 is made of, for example, a single crystal 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. Further, the diaphragm 6 is formed thin by the thickness of the boron diffusion layer formed by diffusing boron (B) from the surface of the silicon substrate to form a boron diffusion layer, stopping etching by wet etching.

  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. Further, a hole penetrating the electrode substrate 3 described later is provided in 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, for example. 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 is provided with a recess 32 at a surface position facing the diaphragm 6 of the cavity substrate 2. The recess 32 is formed at a desired depth by etching. And in each recessed part 32, the individual electrode 5 which consists of ITO (Indium Tin Oxide: Indium tin oxide) generally is formed by thickness of 100 nm, for example. Therefore, the substantial gap (gap) G formed between the diaphragm 6 and the individual electrode 5 is the depth of the recess 32, the thickness of the individual electrode 5, and the first surface formed on the surface of the individual electrode 5. This is determined by the thickness of the insulating film 7 and the thickness of the second insulating film 8 formed on the surface of the diaphragm 6. Since the gap G greatly affects the ejection characteristics of the ink jet head, the depth of the recess 32, the thickness of the individual electrode 5, the thickness of the first insulating film 7, and the thickness of the second insulating film 8 are determined with high accuracy. Need to be formed.

The individual electrode 5 has a terminal portion 5a connected to a flexible wiring board (not shown). As shown in FIGS. 2 and 5, the terminal portion 5 a is exposed in the electrode extraction portion 34 in which the end portion of the cavity substrate 2 is opened for wiring.
The open end of the gap G formed between the diaphragm 6 and the individual electrode 5 is sealed with a sealing material 35 made of resin such as epoxy. Thereby, moisture and dust can be prevented from entering the gap between the electrodes, and the reliability of the inkjet head 10 can be kept high.

  As described above, the nozzle substrate 1, the cavity substrate 2, and the electrode substrate 3 are bonded to each other as shown in FIG. That is, the cavity substrate 2 and the electrode substrate 3 are bonded by anodic bonding, and the nozzle substrate 1 is bonded to the upper surface (the upper surface in FIG. 2) of the cavity substrate 2 by adhesion or the like.

Finally, as shown in FIGS. 2 and 5 in a simplified manner, the drive control circuit 9 such as a driver IC is connected to the terminal portion 5a of each individual electrode 5 and the common electrode 26 on the upper surface of the cavity substrate 2 with the flexible wiring board ( (Not shown).
Thus, the ink jet head 10 is completed.

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 9, the diaphragm 6 is attracted to and attracted to the individual electrode 5 side to generate a negative pressure in the discharge chamber 21. Thus, the ink in the reservoir 23 is sucked to generate ink vibration (meniscus vibration). When the voltage 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.

Here, an electrostatic actuator having an insulating film will be described.
The electrostatic pressure (generated pressure) P that attracts the diaphragm 6 during driving is E, the electrostatic energy is E, the arbitrary position of the diaphragm 6 with respect to the individual electrode 5 is x, the area of the diaphragm 6 is S, and the applied voltage is Assuming V, the thickness of the insulating film is t, the dielectric constant in vacuum is ε ₀ , and the relative dielectric constant of the insulating film is ε _r , the following expression is obtained.

Further, average pressure P _e at the time of driving the diaphragm 6, the distance to the individual electrode 5 from the diaphragm 6 when the diaphragm 6 is not driven (the distance of the gap) as d, the formula: The

The average pressure P _e in the electrostatic actuator in the case where an insulating film of different materials as in the present embodiment 1, the thickness of the alumina film 8a of the second insulating film 8 t _1, the hafnium oxide film 8b the thickness t _2, t ₃ the total thickness of the silicon oxide film of the first and second insulating films 7 and 8, ₁ the dielectric constant of alumina epsilon, the dielectric constant of the hafnium oxide epsilon _2, oxide When the relative dielectric constant of silicon is ε ₃ , the expression (3) can be derived from the expression (2).

From the above formula (2), it can be seen that the average pressure _Pe increases as the relative dielectric constant of the insulating film increases or as the ratio of the relative dielectric constant to the thickness of the insulating film (t / ε) decreases. Therefore, when a high-k material having a higher dielectric constant than silicon oxide is applied as the insulating film, the generated pressure in the electrostatic actuator can be increased.
Further, in the case of the inkjet head 10 to which the High-k material is applied as the insulating film, it is possible to obtain power necessary for ejecting ink droplets even if the area of the diaphragm 6 is reduced. For this reason, in the inkjet head 10, the width of the diaphragm 6 can be reduced, and the pitch of the discharge chambers 21, that is, the pits of the nozzles 11, can be increased to increase the resolution, and higher-definition printing can be performed at high speed. The inkjet head 10 which can be obtained can be obtained. Further, by shortening the length of the diaphragm 6, the responsiveness in the ink flow path can be improved and the drive frequency can be increased, and higher-speed printing can be performed.
Further, for example, if the relative dielectric constant of the second insulating film 8 having a laminated structure is doubled as a whole, almost the same generated pressure can be obtained even if the thickness of the second insulating film 8 is doubled. It can be seen that the 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) of the electric actuator can be almost doubled.

Table 1 shows characteristics of various insulating films applied in the first to fourth embodiments of the present invention. From Table 1, both alumina (Al ₂ O ₃ ) and hafnium oxide (HfO ₂ ) have a very large relative dielectric constant compared to silicon oxide (SiO ₂ ), but in terms of dielectric strength and junction strength, they are more than silicon oxide. Inferior. Therefore, it is desirable to appropriately combine these high dielectric materials to form a laminated structure, rather than using a high dielectric material such as alumina or hafnium oxide alone as the insulating film.

Further, from the above formulas (2) and (3), the parameter related to the improvement of the generated pressure of the electrostatic actuator is the ratio of the relative dielectric constant to the thickness of the insulating film (t / ε), or the first embodiment. In the case where the insulating film is made of three kinds of different materials as shown in FIG. 4, since it is the sum of the ratio of the relative dielectric constant to the thickness of the insulating film (t ₁ / ε ₁ + t ₂ / ε ₂ + t ₃ / ε ₃ ), Table 2 shows the calculated values of this parameter.

  Table 2 shows the case of the conventional example and the first embodiment. In the conventional example, only silicon oxide is formed as an insulating film with a thickness of 110 nm. As shown in FIG. 3, the first embodiment has a thickness of 30 nm for alumina, 20 nm for hafnium oxide, and a total thickness of 80 nm for silicon oxide. It is formed in this way. In the first and subsequent embodiments, the relative dielectric constant was calculated assuming that silicon oxide was 3.8, alumina was 7.8, and hafnium oxide was 18.0.

As described above, the electrostatic actuator according to the first embodiment forms a silicon oxide film as the first insulating film 7 on the individual electrode 5 side, and the diaphragm as the second insulating film 8 on the diaphragm 6 side. Since the high-k material of the alumina film 8a and the hafnium oxide film 8b is laminated from the 6th side, and the silicon oxide film 8c is laminated on the outermost surface, the conventional electrostatic actuator provided with only the silicon oxide film Has the following effects.
(1) The generated pressure of the actuator is improved.
By stacking the high-k materials of the alumina film and the hafnium oxide film, the value of t / ε can be reduced as shown in Table 2, so that the generation pressure of the electrostatic actuator, that is, the discharge pressure of the inkjet head can be improved. it can.
(2) A dielectric strength can be ensured.
Since the silicon oxide film and the alumina film having an excellent withstand voltage are formed with a sufficient thickness, the necessary withstand voltage can be ensured.
(3) High voltage driving is possible.
Since the alumina film and the hafnium oxide film having a high relative dielectric constant are formed to the required thickness, the dielectric constant of the insulating film of the electrostatic actuator is improved and high voltage driving is possible.
(4) Bonding strength can be ensured.
By laminating the silicon oxide film on the high-k material, the cavity substrate and the electrode substrate are anodically bonded via the silicon oxide film, so that a bonding strength equivalent to that of a conventional electrostatic actuator can be secured. In addition, since silicon oxide is joined to each other, there is an effect that moisture can be surely prevented from entering the actuator.
(5) Leakage current can be reduced.
By stacking the silicon oxide film on the high-k material, the leakage current can be reduced to the same extent as that of the conventional electrostatic actuator.
(6) The actuator can be prevented from being charged.
Since the diaphragm and the individual electrode are repeatedly brought into and out of contact with each other through the same type of silicon oxide film, it is possible to prevent generation of residual charges in the actuator and on the surface of the insulating film, which are accompanied by contact charging by driving the actuator. The driving stability and driving durability of the electric actuator can be realized.

Embodiment 2. FIG.
6 is a schematic cross-sectional view of an inkjet head 10 according to Embodiment 2 of the present invention, FIG. 7 is an enlarged cross-sectional view of a portion B in FIG. 6, and FIG. 8 is an enlarged cross-sectional view along line bb in FIG. In the second and subsequent embodiments, the same reference numerals are given to the portions corresponding to those in the first embodiment unless otherwise specified, and the description thereof is omitted.
In the electrostatic actuator unit 4A according to the second embodiment, the first insulating film 7 on the individual electrode 5 side has a structure in which high-k materials of an alumina film 7a and a hafnium oxide film 7b are stacked, and the second insulating film Reference numeral 8 denotes a single-layer structure composed of only a silicon oxide film. However, in this case, silicon oxide is an insulating material suitable for anodic bonding, but alumina and hafnium oxide have a problem in terms of bonding strength. Therefore, the first insulating film 7 is formed on the bonding portion 36 of the electrode substrate 3. The alumina film 7a and the hafnium oxide film 7b are not provided, or these insulating films are removed. Thereby, since the cavity substrate 2 and the electrode substrate 3 can be bonded via the silicon oxide film of the second insulating film 8, it is possible to ensure a bonding strength equivalent to that of the conventional electrostatic actuator.
Regarding the film thickness, the alumina film 7a of the first insulating film 7 is 30 nm, the hafnium oxide film 7b is 20 nm, and the silicon oxide film of the second insulating film 8 is 80 nm. The distance of the gap G is 200 nm, and the thickness of the individual electrode 5 is 100 nm.

  Table 3 shows values calculated for parameters (ratio of relative dielectric constant to insulating film thickness) related to improvement of the generated pressure of the electrostatic actuator of the second embodiment. Conventional examples in Table 3 are the same as those in Table 2.

The electrostatic actuator according to the second embodiment has a configuration in which high-k materials of an alumina film 7a and a hafnium oxide film 7b are stacked as the first insulating film 7 on the individual electrode 5 side. Since the silicon oxide film is formed as the second insulating film 8, the following effects are obtained.
Regarding the pressure generated by the actuator, the pressure generated by the actuator can be improved by laminating high-k materials of an alumina film and a hafnium oxide film.
With respect to the withstand voltage, since the silicon oxide film and the alumina film having a high withstand voltage are formed with sufficient thickness, the necessary withstand voltage can be secured.
For high-voltage driving, an alumina film and a hafnium oxide film having a high relative dielectric constant are formed to the required thickness, so the dielectric constant of the insulating film of the electrostatic actuator is improved and high-voltage driving is possible. .
As for the bonding strength, since the bonded portion is bonded between silicon oxides, it is possible to ensure a bonding strength equivalent to that of a conventional electrostatic actuator.

Moreover, the following effects are obtained by providing the high-k material alumina film and the hafnium oxide film on the individual electrode side on the glass substrate as in the second embodiment.
Alumina and hafnium oxide have a lower bonding strength than silicon oxide. Therefore, in order to ensure a sufficient bonding strength, it is necessary to completely remove the alumina film and the hafnium oxide film at the bonded portion before bonding.
When an alumina film and a hafnium oxide film are formed on the vibration plate side, very high-precision patterning is required to completely remove the alumina film and the hafnium oxide film at the junction. If the alumina film and the hafnium oxide film are removed in a range wider than the area of the junction, there is a problem that a portion having a low withstand voltage is partially generated in the actuator and the withstand voltage is lowered. In addition, if the alumina film and hafnium oxide film can only be removed within a narrower area than the joint area, the alumina film and hafnium oxide film, which could not be removed slightly, may partially reduce the joint strength of the actuator. There is.
On the other hand, when an alumina film or hafnium oxide film is formed on the glass substrate side, complete removal by patterning is sufficient to completely remove the alumina film and hafnium oxide film at the bonding portion. The alumina film and the hafnium oxide film can be easily removed because it is provided at a lower position. Therefore, the bonding strength of the actuator can be ensured more reliably and easily.
Accordingly, when only an alumina film or hafnium oxide film having a bonding strength lower than that of the silicon oxide film is used as the insulating film, it is desirable to form the alumina film and the hafnium oxide film on the individual electrode substrate side.
In this case, it is preferable to further provide a silicon oxide film in the actuator in order to ensure a withstand voltage. In this case, since the silicon oxide film formed by the thermal oxidation method has a higher withstand voltage than the silicon oxide film formed by the CVD method, it is desirable to form the silicon oxide film on the silicon substrate side by the thermal oxidation method.

Embodiment 3. FIG.
9 is a schematic cross-sectional view of an inkjet head 10 according to Embodiment 3 of the present invention, FIG. 10 is an enlarged cross-sectional view of a portion C in FIG. 9, and FIG. 11 is an enlarged cross-sectional view along line cc in FIG.
In the third embodiment, contrary to the second embodiment, the second insulating film 8 on the vibration plate 6 side is configured to stack high-k materials. That is, a high-k hafnium oxide film 8b and an alumina film 8a are stacked as the second insulating film 8, and a silicon oxide film is formed as the first insulating film 7 on the individual electrode 5 side.
In this case, since the silicon oxide film is formed on the electrode substrate 3 side, it is not necessary to remove the silicon oxide film in the joint portion 36.
Regarding the film thickness, the silicon oxide film of the first insulating film 7 is 80 nm, the alumina film 8a of the second insulating film 8 is 30 nm, and the hafnium oxide film 8b is 20 nm. The distance of the gap G is 200 nm, and the thickness of the individual electrode 5 is 100 nm.

  Table 4 shows values obtained by calculating parameters (ratio of relative dielectric constant to insulating film thickness) related to improvement of the generated pressure of the electrostatic actuator of the third embodiment. Conventional examples in Table 4 are the same as those in Table 2.

In the electrostatic actuator according to the third embodiment, as described above, the first insulating film 7 on the individual electrode 5 side is formed of a silicon oxide film, and the second insulating film 8 on the diaphragm 6 side is oxidized with the alumina film 8a. Since the high-k material of the hafnium film 8b is laminated, the generated pressure of the actuator can be improved.
With respect to the withstand voltage, since the silicon oxide film having an excellent withstand voltage is provided with a sufficient thickness, the necessary withstand voltage can be ensured.
For high-voltage driving, an alumina film and a hafnium oxide film having a high relative dielectric constant are formed to the required thickness, so the dielectric constant of the insulating film of the electrostatic actuator is improved and high-voltage driving is possible. .
As for the bonding strength, since an alumina film having a relatively good bonding strength is formed on the bonding surface side, the minimum bonding strength required for the electrostatic actuator can be ensured.
Furthermore, since it is not necessary to remove the silicon oxide film at the junction 36, the manufacturing process can be simplified, leading to cost reduction.

Embodiment 4 FIG.
12 is a schematic cross-sectional view of an inkjet head 10 according to Embodiment 4 of the present invention, FIG. 13 is an enlarged cross-sectional view of a portion D in FIG. 12, and FIG. 14 is a dd enlarged cross-sectional view in FIG.

The electrostatic actuator unit 4C according to the fourth embodiment has a structure in which high-k materials of a hafnium oxide film 7b and an alumina film 7a are stacked as the first insulating film 7 on the individual electrode 5 side. As the second insulating film 8, a high-k alumina film is formed.
Further, the bonding portion 36 of the electrode substrate 3 is configured not to provide (remove) the portion of the first insulating film 7 made of the hafnium oxide film 7b and the alumina film 7a. Then, an alumina film having relatively good bonding strength is formed on the bonding surface side of the cavity substrate 2.
Regarding the film thickness, the hafnium oxide 7b of the first insulating film 7 is 20 nm, the alumina film 7a is 40 nm, and the alumina film of the second insulating film 8 is 100 nm. The thickness of the individual electrode 5 is 100 nm, and the distance of the gap G is 200 nm.

  Table 5 shows values obtained by calculating parameters (ratio of relative dielectric constant to insulating film thickness) related to improvement of the generated pressure of the electrostatic actuator of the fourth embodiment. Conventional examples in Table 5 are the same as those in Table 2.

As in the fourth embodiment, the first and second insulating films are both made of a high-k material, and one of the insulating films on the individual electrode side is preferably constructed by stacking high-k materials. Thus, the pressure generated by the actuator can be further improved, and the actuator can be driven at a higher voltage. In addition, by providing an alumina film with relatively good bonding strength on the bonding surface side, it is possible to ensure the minimum withstand voltage and bonding strength necessary for the electrostatic actuator.
Further, since the second insulating film 8 formed on the facing surface of the diaphragm 6 is the same kind of alumina film as the first insulating film 8 formed on the facing surface of the individual electrode 5, contact by driving of the actuator is performed. An increase in the amount of charge of the actuator accompanying charging can be minimized, and the drive durability of the actuator is improved.

  Next, an outline of an example of a method for manufacturing the inkjet head 10 will be described with reference to FIGS. 15 to 17. 15 is a flowchart showing a schematic flow of the manufacturing process of the inkjet head 10, FIG. 16 is a cross-sectional view showing an outline of the manufacturing process of the electrode substrate 3, and FIG. 17 is a cross-sectional view showing an outline of the manufacturing process of the inkjet head 10. .

  In FIG. 15, steps S <b> 1 to S <b> 3 indicate the manufacturing process of the electrode substrate 3, and steps S <b> 4 and S <b> 5 indicate the manufacturing process of the silicon substrate from which the cavity substrate 2 is based. Here, although the manufacturing method of the inkjet head 10 shown mainly in Embodiment 1 is demonstrated, other Embodiments 2-4 are also mentioned as needed.

The electrode substrate 3 is manufactured as follows.
First, a recess 32 having a desired depth is formed on a glass substrate 300 made of borosilicate glass or the like having a thickness of about 1 mm by etching with hydrofluoric acid using, for example, a gold / chromium etching mask. Note that the recess 32 has a groove shape slightly larger than the shape of the individual electrode 31, 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 electrodes 5 are formed on the substrate (S1 in FIG. 15, FIG. 16A).

Next, as the first insulating film 7 on the individual electrode 5 side, RF-CVD (Chemical Vapor Deposition) using TEOS (Tetraethoxysilane) as a raw material gas on the entire surface on the bonding surface side of the glass substrate 300. A silicon oxide film (SiO ₂ ) is formed with a thickness of 30 nm by the method (S2 in FIG. 15, FIG. 16B). In FIG. 16B, the silicon oxide film on the bonding surface of the glass substrate 300 is removed, but the silicon oxide film on the bonding portion 36 may not be removed.

Next, only the portion corresponding to the terminal portion 5a of the individual electrode 5 on the glass substrate 300 is patterned, and the first insulating film 7 on the terminal portion 5a is formed by RIE (Reactive Ion Etching) dry etching using CHF ₃ . The portion is removed (S3 in FIG. 15, FIG. 16C). Thereafter, a hole 33a to be the ink supply hole 33 is formed by blasting or the like.
As described above, the electrode substrate 3 of Embodiment 1 can be manufactured.

In the case of the second embodiment, as the first insulating film 7 on the individual electrode 5 side, first, an alumina film 7a is formed on the bonding surface side surface of the glass substrate 300 with a desired thickness by an ECR (Electron Cyclotron Resonance) sputtering method. After the film is formed on the entire surface, a hafnium oxide film 7b is further formed thereon with a desired thickness by the same ECR sputtering method. Thereafter, only the portions corresponding to the bonding portions 36 on the glass substrate 300 and the terminal portions 5a of the individual electrodes 5 are patterned, and the first insulating film on the bonding portions 36 and the terminal portions 5a is formed by RIE dry etching using CHF _3. 7 parts are removed simultaneously.
The case of the third embodiment is the same as the case of the first embodiment.
In the case of the fourth embodiment, only the order of the high dielectric material to be laminated is changed as the first insulating film 7 and is basically the same as the case of the second embodiment.

  The cavity substrate 2 is manufactured after anodic bonding of the silicon substrate 200 to the electrode substrate 3 manufactured as described above.

First, for example, 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 surface of the silicon substrate 200 having a thickness of 280 μm (S4 in FIG. 15). Next, on the surface (lower surface) of the boron diffusion layer 201 of the silicon substrate 200, an alumina film 8a is first formed as a second insulating film 8 to a thickness of 30 nm by ECR sputtering. Next, a hafnium oxide film 8b is formed on the entire surface of the alumina film 8a by the same ECR sputtering method. Finally, a silicon oxide film 8c having a thickness of 50 nm is formed on the hafnium oxide film 8b by RF-CVD using TEOS as a source gas (S4 in FIG. 15, FIG. 17A).
A silicon oxide film with a thickness of 80 nm is formed by thermal oxidation or the above TEOS-CVD method (S5 in FIG. 15, FIG. 17A).

Note that in the case of Embodiment 2, it is only necessary to form a silicon oxide film over the entire surface by thermal oxidation or the above-described RF-CVD method.
In the case of the third embodiment, a hafnium oxide film is first formed on the entire surface of the boron diffusion layer 201 by ECR sputtering, and then an alumina film is formed on the entire surface thereof.
In the case of Embodiment 4, an alumina film may be formed on the entire surface of the boron diffusion layer 201 by ECR sputtering.

  Next, the silicon substrate 200 manufactured as described above is aligned on the electrode substrate 3 and anodic bonded (S6 in FIG. 15, FIG. 17B).

  Next, the entire surface of the bonded silicon substrate 200 is polished to reduce the thickness to, for example, about 50 μm (S7 in FIG. 15, FIG. 17C), and the entire surface of the silicon substrate 200 is wetted. Light etching is performed to remove the processing trace (S8 in FIG. 15).

  Next, resist patterning is performed by photolithography on the surface of the bonded silicon substrate 200 processed into a thin plate (S9 in FIG. 15), and ink channel grooves are formed by performing wet etching with an aqueous potassium hydroxide solution (FIG. 15). 15 S10). As a result, a recess 22 serving as the discharge chamber 21, a recess 24 serving as the reservoir 23, and a recess 27 serving as the electrode extraction portion 34 are formed (FIG. 17D). 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.

Next, the ICP (Inductively Coupled Plasma) dry etching is used to remove the bottom of the concave portion 27 and open the electrode lead-out portion 34 (FIG. 17E), and then the moisture adhering to the inside of the electrostatic actuator is removed. It is removed (S11 in FIG. 15). Moisture removal is performed in a nitrogen atmosphere after the silicon substrate is placed in, for example, a vacuum chamber and heated and evacuated. Then, after the required time has elapsed, a sealing material 35 such as an epoxy resin is applied to the gap opening end portion in a nitrogen atmosphere and hermetically sealed (S12 in FIG. 15, FIG. 17 (f)). Thus, after removing the moisture adhering to the inside of the electrostatic actuator (in the gap), the driving durability of the electrostatic actuator can be improved by hermetically sealing.
Further, the ink supply hole 33 is formed by penetrating the bottom of the recess 24 by microblasting or the like. Further, an ink protective film (not shown) made of a TEOS film is formed on the surface of the silicon substrate by plasma CVD in order to prevent corrosion of the ink flow path grooves. 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.
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 bonding (S13 in FIG. 15, FIG. 17 (g)). Finally, when the individual head chips are cut by dicing, the above-described main body of the inkjet head 10 is completed (S14 in FIG. 15).

  According to the manufacturing method of the ink jet head 10 of Embodiment 1, a silicon oxide film is formed on the individual electrode side on the glass substrate, and an alumina film and a hafnium oxide film High-k are formed on the entire bonding surface of the silicon substrate on the vibration plate side. By stacking materials and further stacking a silicon oxide film on the entire surface, the pressure generated by the actuator is improved, and by forming a silicon oxide film, an electrostatic actuator with excellent withstand voltage and bonding strength Ink jet heads can be manufactured. Furthermore, because the opposing surface side of each electrode is the same type of dielectric material, stable drive is achieved by eliminating residual charges on the actuator and insulating film surfaces due to contact charging of the actuator due to the contact and release of the diaphragm. In addition, an electrostatic actuator having excellent driving durability can be manufactured.

  According to the method of manufacturing the inkjet head 10 of the second embodiment, the high-k material of the alumina film and the hafnium oxide film is laminated on the individual electrode side on the glass substrate, so that the generated pressure of the actuator is improved, and the diaphragm By forming a silicon oxide film on the entire bonding surface of the silicon substrate on the side, an inkjet head including an electrostatic actuator having excellent withstand voltage and bonding strength can be manufactured at low cost.

  According to the method of manufacturing the inkjet head 10 of the third embodiment, a silicon oxide film is formed on the individual electrode side on the glass substrate, and a high-k of a hafnium oxide film and an alumina film is formed on the entire bonding surface of the silicon substrate on the vibration plate side. By stacking materials, the pressure generated by the actuator is improved, and the manufacturing process can be simplified because it is not necessary to remove the silicon oxide film at the bonding portion of the glass substrate, and the electrostatic actuator has excellent dielectric strength and bonding strength. Ink jet heads can be manufactured more inexpensively.

According to the method of manufacturing the inkjet head 10 of the fourth embodiment, the high-k material of the alumina film and the hafnium oxide film is laminated on the individual electrode side on the glass substrate, and the alumina is formed on the entire bonding surface of the silicon substrate on the vibration plate side. By forming the insulating film made of the high-k material of the film, it is possible to manufacture an ink jet head including an electrostatic actuator in which the pressure generated by the actuator is further improved. In addition, because the opposing surface side of each electrode is the same type of high dielectric material, stable drive is achieved by eliminating residual charges on the actuator and the insulating film surface due to contact charging of the actuator due to contact and release of the diaphragm In addition, an electrostatic actuator having excellent driving durability can be manufactured.
Therefore, according to the above manufacturing method, an inkjet head excellent in driving durability and ejection performance can be manufactured at a relatively low cost.

  Since the cavity substrate 2 is manufactured from the silicon substrate 200 in a state of being bonded to the electrode substrate 3 prepared in advance, the cavity substrate 2 is supported by the electrode substrate 3. Even if it is made thin, it does not break or chip, and handling becomes easy. Therefore, there is an effect that the yield is improved as compared with the case where the cavity substrate 2 is manufactured alone.

  In the above embodiment, the electrostatic actuator, the inkjet 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 do. 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 500 as shown in FIG. 21, manufacturing of color filters for liquid crystal displays, 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 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 expanded sectional view of the A section of FIG. The aa expanded sectional view of FIG. FIG. 3 is a top view of the inkjet head of FIG. 2. FIG. 5 is a schematic cross-sectional view of an inkjet head according to Embodiment 2 of the present invention. The expanded sectional view of the B section of FIG. The bb expanded sectional view of FIG. FIG. 6 is a schematic cross-sectional view of an inkjet head according to a third embodiment of the present invention. The expanded sectional view of the C section of FIG. Cc expanded sectional view of FIG. FIG. 6 is a schematic cross-sectional view of an inkjet head according to Embodiment 4 of the present invention. The expanded sectional view of the D section of FIG. Dd expanded sectional drawing of FIG. The flowchart which shows the outline flow of the manufacturing process of an inkjet head. Sectional drawing which shows the outline | summary of the manufacturing process of an electrode substrate. Sectional drawing which shows the outline | summary of the manufacturing process of an inkjet head. 1 is a perspective view of an ink jet printer using an ink jet head according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle substrate, 2 Cavity substrate, 3 Electrode substrate, 4, 4A, 4B, 4C Electrostatic actuator part, 5 Individual electrode (fixed electrode), 6 Vibration plate (movable electrode), 7 1st insulating film, 7a Alumina film 7b Hafnium oxide film, 8 Second insulating film, 8a Alumina film, 8b Hafnium oxide film, 8c Silicon oxide film, 9 Drive control circuit (drive means), 10 Inkjet head, 11 Nozzle hole, 12 Orifice, 21 Discharge chamber , 23 reservoir, 26 common electrode, 32 recess, 33 ink supply hole, 34 electrode takeout part, 35 sealing material, 36 joint part, 200 silicon substrate, 300 glass substrate, 500 inkjet printer.

Claims (15)

A fixed electrode formed on the substrate, a movable electrode disposed opposite to the fixed electrode via a predetermined gap, and an electrostatic force is generated between the fixed electrode and the movable electrode to displace the movable electrode. In an electrostatic actuator comprising a driving means for generating
A first insulating film formed on the opposing surface of the fixed electrode; and a second insulating film formed on the opposing surface of the movable electrode, wherein at least one of the first and second insulating films is An electrostatic actuator comprising an insulating film formed by laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide.   The fixed electrode is formed on a glass substrate, the movable electrode is formed on a silicon substrate, and the glass substrate and the silicon substrate are bonded via a silicon oxide film formed on at least one bonding surface. The electrostatic actuator according to claim 1.   The fixed electrode is formed on a glass substrate, the movable electrode is formed on a silicon substrate, and one of the insulating films formed on the glass substrate and the silicon substrate has a relative dielectric constant higher than that of silicon oxide. 2. The electrostatic actuator according to claim 1, wherein the other insulating film is an insulating film formed by laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide.   The fixed electrode is formed on a glass substrate, the movable electrode is formed on a silicon substrate, and the insulating film formed on the outermost surface on the glass substrate and the outermost surface on the silicon substrate is made of the same kind of dielectric material. The electrostatic actuator according to claim 1, wherein the electrostatic actuator is provided.   5. The insulating film formed by laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide is not provided at a joint portion between the glass substrate and the silicon substrate. The electrostatic actuator in any one. The dielectric material is at least one selected from aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), hafnium nitride silicate (HfSiN), and hafnium oxynitride silicate (HfSiON). The electrostatic actuator according to any one of 1 to 5. A fixed electrode formed on the substrate, a movable electrode disposed opposite to the fixed electrode via a predetermined gap, and an electrostatic force is generated between the fixed electrode and the movable electrode to displace the movable electrode. In the manufacturing method of the electrostatic actuator provided with the drive means for generating
On the glass substrate on which the fixed electrode is formed, as a first insulating film, a step of laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide;
Forming a silicon oxide film as a second insulating film on the entire surface of the silicon substrate on which the movable electrode is formed and the glass substrate; and
Removing a portion of the first insulating film in a joint portion between the glass substrate and the silicon substrate;
Anodically bonding the glass substrate and the silicon substrate through the silicon oxide film;
Etching from the surface opposite to the bonding surface of the silicon substrate to form the movable electrode;
Removing moisture present in a gap formed between the fixed electrode and the movable electrode;
Hermetically sealing the gap;
A method for manufacturing an electrostatic actuator, comprising: A fixed electrode formed on the substrate, a movable electrode disposed opposite to the fixed electrode via a predetermined gap, and an electrostatic force is generated between the fixed electrode and the movable electrode to displace the movable electrode. In the manufacturing method of the electrostatic actuator provided with the drive means for generating
Forming a silicon oxide film as a first insulating film on the glass substrate on which the fixed electrode is formed;
A step of laminating a dielectric material having a relative dielectric constant higher than that of silicon oxide as a second insulating film over the entire bonding surface of the silicon substrate on which the movable electrode is formed with the glass substrate;
Anodically bonding the glass substrate and the silicon substrate through the silicon oxide film;
Etching from the surface opposite to the bonding surface of the silicon substrate to form the movable electrode;
Removing moisture present in a gap formed between the fixed electrode and the movable electrode;
Hermetically sealing the gap;
A method for manufacturing an electrostatic actuator, comprising: A fixed electrode formed on the substrate, a movable electrode disposed opposite to the fixed electrode via a predetermined gap, and an electrostatic force is generated between the fixed electrode and the movable electrode to displace the movable electrode. In the manufacturing method of the electrostatic actuator provided with the drive means for generating
On the glass substrate on which the fixed electrode is formed, as a first insulating film, a step of laminating dielectric materials having a relative dielectric constant higher than that of silicon oxide;
Forming an insulating film made of a dielectric material having a relative dielectric constant higher than that of silicon oxide as a second insulating film on the entire surface of the silicon substrate on which the movable electrode is formed and the glass substrate; and
Removing a portion of the first insulating film in a joint portion between the glass substrate and the silicon substrate;
Anodically bonding the glass substrate and the silicon substrate;
Etching from the surface opposite to the bonding surface of the silicon substrate to form the movable electrode;
Removing moisture present in a gap formed between the fixed electrode and the movable electrode;
Hermetically sealing the gap;
A method for manufacturing an electrostatic actuator, comprising:   10. The method for manufacturing an electrostatic actuator according to claim 7, wherein a portion of the first insulating film in the bonding portion of the glass substrate is patterned and removed by dry etching. The dielectric material includes at least one selected from aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), hafnium nitride silicate (HfSiN), and hafnium oxynitride silicate (HfSiON). The method for manufacturing an electrostatic actuator according to claim 7.   The method for manufacturing an electrostatic actuator according to claim 7, wherein the gap is sealed in a nitrogen atmosphere. A nozzle substrate having a single or a plurality of nozzle holes for discharging droplets; a cavity substrate in which a recess serving as a discharge chamber communicating with each of the nozzle holes is formed between the nozzle substrate; and the discharge chamber In a liquid droplet ejection head comprising an electrode substrate on which an individual electrode is disposed so as to be opposed to a diaphragm configured at a bottom portion of the diaphragm with a predetermined gap.
A droplet discharge head comprising the electrostatic actuator according to claim 1. A nozzle substrate having a single or a plurality of nozzle holes for discharging droplets; a cavity substrate in which a recess serving as a discharge chamber communicating with each of the nozzle holes is formed between the nozzle substrate; and the discharge chamber In a method of manufacturing a liquid droplet ejection head, comprising: an electrode substrate on which an individual electrode disposed opposite to a diaphragm configured at a bottom portion of the diaphragm with a predetermined gap is formed;
13. A method for manufacturing a droplet discharge head, wherein the method for manufacturing an electrostatic actuator according to claim 7 is applied.   A droplet discharge apparatus comprising the droplet discharge head according to claim 13.

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