JP4123613B2 - Electrostatic actuator, inkjet head, silicon substrate, etching mask, and method for manufacturing silicon substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic actuator, an inkjet head, a silicon substrate, an etching mask, and a method for manufacturing a silicon substrate. In particular, the present invention relates to an electrostatic actuator and an ink jet head that are driven by an electrostatic force generated by applying a voltage between a diaphragm and a counter electrode, and methods for manufacturing these.
[0002]
[Prior art]
In an inkjet head of an inkjet printer, fine printing is required. Such an ink jet head is manufactured by forming a micro-structure actuator that ejects ink onto a silicon wafer using a semiconductor microfabrication technique. In addition to inkjet heads, microactuators such as micromirrors have been proposed.
[0003]
In such a micro-structure actuator, electrostatic force can be used as a drive source. For example, the present applicant has disclosed an ink jet head that discharges ink droplets using electrostatic force in Japanese Patent Laid-Open Nos. 5-50601 and 6-70882.
[0004]
In this type of inkjet head, the bottom surface of the ink flow path communicating with the ink nozzle is formed as a vibration plate that can be elastically deformed. A substrate is disposed opposite to the diaphragm at a constant interval.
[0005]
A plurality of ink nozzles, ink flow paths, and diaphragms are formed, and a counter electrode facing each diaphragm is disposed on the substrate.
[0006]
A wiring pattern is electrically connected to the diaphragm and the counter electrode from an opening (through hole). When a voltage is applied between these wiring patterns, an electrostatic force is generated in the diaphragm and the counter electrode. Due to this electrostatic force, the diaphragm is electrostatically attracted toward the substrate and displaced (vibrates).
[0007]
On the other hand, since the space (vibration chamber) between the diaphragm and the counter electrode is hermetically sealed by the sealing member, the internal pressure fluctuates in the ink flow path with the vibration of the diaphragm. Ink droplets are ejected from the ink nozzles. By controlling the voltage applied to the wiring pattern, a so-called ink-on-demand system is realized in which ink droplets are ejected only when necessary for recording.
[0008]
The diaphragm of an electrostatic actuator such as an ink jet head can be formed by wet anisotropic etching utilizing the anisotropy of silicon. In this case, in the silicon wafer having the surface orientation (110), the wall surface (surface orientation (110)) of the hole formed by etching is perpendicular to the front surface and the back surface. Thus, the density of the diaphragm can be increased.
[0009]
On the other hand, when a silicon wafer having a (110) plane orientation is subjected to wet anisotropic etching to form a through hole in which a wiring pattern conducting to the counter electrode is formed, the shape of the through hole in the (110) plane on the front and back surfaces Is a parallelogram with one inner angle of 70.19 degrees.
[0010]
[Problems to be solved by the invention]
However, when the planar shape of the through hole is a parallelogram, the size of the through hole is increased. For this reason, the size of an actuator such as an ink jet head is increased, and the number that can be manufactured from one wafer is reduced, resulting in a problem that the cost is increased. Moreover, since the through-hole is large, the handling property in production is deteriorated, and the strength is lowered.
[0011]
The present invention has been made to solve such problems, and an object thereof is to provide an electrostatic actuator, an inkjet head, a silicon substrate, an etching mask, and a method for manufacturing the silicon substrate. In particular, it is an object of the present invention to provide an electrostatic actuator and an inkjet head that are easy to handle and inexpensive, and a manufacturing method thereof, and an electrostatic actuator, an inkjet head, and a manufacturing method thereof.
[0012]
[Means for Solving the Problems]
The following inventions are provided as means for solving the above problems.
[0013]
The electrostatic actuator of the present invention has an opening in a polygonal shape in which a plurality of parallelograms continuous on the (110) plane are overlapped, and an opening in which a wiring pattern is arranged, and a thin wall on the (110) plane. A (110) silicon substrate having a diaphragm that is electrically connected to the wiring pattern and is displaced by static electricity, a counter electrode that is disposed opposite to the diaphragm and that is electrically connected to the wiring pattern disposed in the opening, and wiring Drive means for applying a voltage to the diaphragm and the counter electrode from the pattern to displace the diaphragm.
[0014]
Further, it is desirable that the pitch of the parallelograms of the openings is substantially the same as the pitch of the wiring pattern.
[0015]
The electrostatic actuator of the present invention preferably further includes a sealing member for hermetically sealing a vibration chamber formed by the vibration plate and the counter electrode.
[0016]
Moreover, as for the electrostatic actuator of this invention, it is desirable for a sealing member to be an epoxy-type low temperature thermosetting type, and to have a viscosity of 1000 cP-14000 cP.
[0017]
The inkjet head of the present invention has an opening in a polygonal shape in which a plurality of parallelograms continuous in the (110) plane are overlapped, and an opening in which a wiring pattern is arranged, and is provided thinly in the (110) plane. A (110) silicon substrate having a diaphragm that is electrically connected to the wiring pattern and displaced by static electricity, a counter electrode that is disposed opposite to the diaphragm and that is electrically connected to the wiring pattern disposed in the opening, and the wiring pattern A voltage is applied to the diaphragm to generate static electricity between the diaphragm and the counter electrode, and the driving means for displacing the diaphragm and the diaphragm and the counter electrode are hermetically sealed. A sealing member provided with an ink chamber that varies in pressure, and an ink nozzle that communicates with the ink chamber and ejects ink droplets accumulated in the ink chamber due to the pressure variation in the ink chamber.
[0018]
In addition, the inkjet head of the present invention includes a plurality of wiring patterns in which a diaphragm, ink chambers, and ink nozzles are partitioned and formed on a (110) silicon substrate, and are electrically connected to the counter electrodes of the plurality of diaphragms. Is preferably disposed in the opening. In this case, it is preferable that the pitch of the parallelograms of the openings is substantially the same as the pitch of the wiring pattern.
[0019]
The (110) silicon substrate of the present invention has an opening having a polygonal shape in which a plurality of parallelograms continuous in the (110) plane are overlapped, and the pitch of the overlap of these parallelograms is (110 ) It is configured to be less than the thickness of the silicon substrate.
[0020]
In the (110) silicon substrate of the present invention, it is desirable that one of the internal angles of the parallelogram is 70.19 degrees.
[0021]
The mask for anisotropic etching of the (110) silicon substrate of the present invention has an inner angle out of the vertices of a polygon formed by superimposing a parallelogram whose inner angle is 70.19 degrees parallel to the long side. Is configured to have a mask pattern having a shape in which the correction pattern is extended in parallel with the long side of the parallelogram from the apex of 289.81 degrees.
[0022]
The (110) silicon substrate manufacturing method of the present invention has an inner angle of 289.81 among the vertices of a polygon formed by superimposing parallelograms whose inner angles are 70.19 degrees parallel to their long sides. Masking the (110) plane of the (110) silicon wafer with a mask pattern having a shape in which the correction pattern is extended in parallel to the long side of the parallelogram from the apex of the degree, and the masked (110) silicon wafer And an anisotropic etching step.
[0023]
In the (110) silicon substrate manufacturing method of the present invention, it is desirable to set the length of the correction pattern based on the etching rate of anisotropic etching.
[0024]
In the (110) silicon substrate manufacturing method of the present invention, two types of mask pattern correction pattern lengths are set based on the etch rates on both sides of the (110) silicon wafer, and the two types of mask patterns are used. , (110) Both sides of the silicon wafer can be masked, and the (110) silicon wafer can be anisotropically etched from both sides.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an inkjet head which is an electrostatic actuator to which the present invention is applied will be described with reference to the drawings.
[0026]
1 is a cross-sectional view of an inkjet head as an electrostatic actuator to which the present invention is applied, FIG. 2 is a perspective view thereof, and FIG. 3 is an exploded perspective view thereof.
[0027]
The present embodiment is a face eject type ink jet head in which ink droplets are ejected from nozzles provided on a nozzle plate.
[0028]
As shown in these drawings, the inkjet head 1 has a silicon substrate 2 sandwiched therebetween, a silicon nozzle plate 3 on the upper side, and a glass substrate 4 made of borosilicate glass having a thermal expansion coefficient close to that of silicon on the lower side. It has a three-layer structure.
[0029]
The center silicon substrate 2 is a silicon single crystal substrate having a (110) plane orientation on the surface and a thickness of 180 μm. When silicon having a plane orientation of (110) is subjected to wet anisotropic etching, four planes perpendicular to the silicon surface are formed. For this reason, when a groove is formed on a silicon wafer having a surface orientation (110) using wet anisotropic etching, the density of the groove can be increased as compared with a case where the silicon wafer having a surface orientation (100) is formed.
[0030]
The silicon substrate 2 is processed with grooves that function as five independent ink chambers 5 and one common ink chamber 6 by performing wet anisotropic etching from the surface thereof.
[0031]
In this embodiment, a 20 weight percent KOH aqueous solution heated to 80 ° C. can be used as an etchant used for wet anisotropic etching of silicon. This concentration can be changed depending on the situation. Further, the composition is not limited to the KOH aqueous solution. For example, an aqueous alkaline solution such as an aqueous ammonia solution or an organic amine-based alkaline aqueous solution can be used.
[0032]
The nozzle plate 3 is a silicon single crystal having a thickness of 180 μm, and the surface has a (100) plane orientation. The nozzle plate 3 is subjected to wet anisotropic etching from the back surface thereof, so that five nozzle grooves 7 are formed at positions corresponding to the tip side portions of the respective ink chambers 5, and are common to the respective ink chambers 5. In order to make the ink chambers 6 communicate with each other, a groove functioning as an ink supply path 9 is processed at a position opposite to the nozzles with respect to each ink chamber. Further, by performing dry anisotropic etching from the surface of the nozzle plate 3, nozzle holes 8 are formed at positions corresponding to the nozzle grooves 7.
[0033]
By joining the nozzle plate 3 and the silicon substrate 2, the five ink chambers 5 independent of the one common ink chamber 6 communicate with each other through the respective ink supply paths 9. Further, the five independent nozzle holes 8 communicate with the respective ink chambers 5.
[0034]
In the present embodiment, the nozzle plate 3 and the silicon substrate 2 can be directly bonded by aligning and bonding and heating to 1000 degrees Celsius. The bonding of the nozzle plate 3 and the silicon substrate 2 is not limited to the direct bonding. For example, after depositing 2000 angstrom gold on the bonding interface between the nozzle plate 3 and the silicon substrate 2 in advance, the nozzle plate 3 and the silicon substrate 2 are bonded. Eutectic bonding can be performed at a low temperature by placing the substrate 2 in a close contact state and heating to 400 ° C. Further, the nozzle plate 3 and the silicon substrate 2 can be bonded with an adhesive.
[0035]
Each independent ink chamber 5 has a thin bottom wall (vibrating plate) 51 and is configured to function as a vibrating plate that can be elastically displaced in the out-of-plane direction, that is, in the vertical direction in FIG. .
[0036]
Next, in the glass substrate 4 positioned below the silicon substrate 2, the bonding surface with the silicon substrate 2, which is the upper surface, is etched shallowly at a position corresponding to each ink chamber 5 of the silicon substrate 2. A recess 16 that constitutes the vibration chamber 15 and a recess that communicates with the recess 16 and constitutes the passage 17 are formed. A segment electrode 18 made of ITO (Indium Tin Oxicide) is formed on the concave surface of the glass substrate 4. The segment electrode 18 has a wiring portion 19 and a terminal portion 20.
[0037]
Here, the facing interval between the bottom wall (vibrating plate) 51 and the segment electrode (counter electrode) 18 disposed opposite thereto, that is, the interval (gap length) G of the vibrating chamber 15 is determined by the depth of the recess 16 and the segment. This is a difference from the thickness of the electrode 18.
[0038]
An ink supply hole 10 is formed on the bottom surface of the common ink chamber 6 of the silicon substrate 2 by dry etching from the back side of the silicon substrate. An ink supply port 11 is also formed in the glass substrate 4 at a position corresponding to the ink supply hole 10. Ink is supplied from an external ink tank (not shown) to the common ink chamber 6 through the ink supply port 11 and the ink supply hole 10. The ink supplied to the common ink chamber 6 is supplied to each independent ink chamber 5 through each ink supply path 9.
[0039]
A through hole 13 for taking out the segment electrode terminal portion 20 is formed in the silicon substrate 2 by performing wet anisotropic etching from the front surface and the back surface of the silicon substrate 2. According to such a forming method, the side surface forming the through hole 13 is generally constituted by a (111) crystal plane, and the discontinuous portion 14 is formed.
[0040]
Here, the shape of the through hole will be described with reference to FIGS. 4, 5, and 6. FIG. 4 is a plan view showing a planar shape of a silicon wafer 101 that constitutes the silicon substrate 2 to which the present invention is applied. FIG. 5 is a plan view showing a planar shape of a silicon wafer 31 that constitutes a conventional silicon substrate 32. FIG. 6 is an explanatory diagram showing the shape of a mask pattern for providing a through hole (opening) in the silicon substrate of the inkjet head.
[0041]
4, the ink chamber 5, the groove functioning as the common ink chamber 6, the ink supply hole 10, the common electrode terminal 22, and the through hole 13 are formed by the processing method described above. Therefore, the silicon substrate 2 is formed by cutting along the one-dot chain line shown in FIG. The through hole 13 has a configuration in which parallelograms indicated by broken lines are continuously overlapped.
[0042]
In this embodiment, one silicon substrate 2 is formed on the silicon wafer 101, but the present invention is not limited to this.
[0043]
The silicon wafer 31 is a silicon single crystal substrate whose surface has a (110) plane orientation. The ink chamber 35, the groove functioning as the common ink chamber 36, the ink supply hole 40, the common electrode terminal 42, and the through hole 43 are formed by the same processing method as in this embodiment. However, the planar shape of the through hole 43 is constituted by one parallelogram. Therefore, the through hole 43 is larger than the through hole 13, and the silicon substrate 32 (the shape indicated by the one-dot chain line in FIG. 5) is larger than the silicon substrate 2.
[0044]
In this embodiment, as shown in FIG. 3, the pitch P of the parallelograms of the through holes 13 is set to 100 μm, which is a dimension of the thickness of the silicon substrate 2 of 180 μm or less. The smaller the pitch P, the smaller the through holes that are formed. In order to take out the common electrode terminal 22 formed in the silicon substrate 2 and the segment electrode terminal 20 formed in the glass substrate 4, the nozzle plate 3 goes around through the through hole 13 formed in the silicon substrate 2. Large through-holes 12 are formed by wet anisotropic etching from the front and back surfaces of the nozzle plate 3. The segment electrode terminals 20 formed on the glass substrate 4 are formed so that the pitch of the segment electrode terminals 20 is substantially the same as the pitch P of the parallelograms of the through holes 13 described above. That is, the pitch of each segment electrode terminal 20 was 100 μm.
[0045]
In this way, by making the pitch P of the through holes 13 and the pitch of the segment electrode terminals 20 the same, the segment electrode terminals 20 are surely arranged in the portions where the side surfaces of the through holes 13 are the (111) plane. It becomes possible. That is, it is possible to prevent an unstable surface such as a slight etching residue formed by a correction pattern in a mask pattern to be described later and the segment electrode terminal 20 from interfering with each other by joining the glass substrate 4 and the silicon substrate 2. It becomes possible. Further, this makes it possible to stably match the capacitances of the actuators, and even if the shape of the through hole 13 is complicated, actuators having the same characteristics can be obtained in the same head.
[0046]
A mask pattern for making the through hole 43 having a shape in which such parallelograms are superimposed will be described with reference to FIG. FIG. 6A shows the shape of a desired through hole. The parallelogram of the through hole has an inner angle of 70.19 degrees that matches the crystal structure of the (110) silicon substrate.
[0047]
FIGS. 6B and 6C show the shapes of the mask patterns on both sides in the case where such a through hole is subjected to wet anisotropic etching from both sides. The shape of the mask pattern shown in FIGS. 6B and 6C is a vertex having an inner angle of 289.81 degrees among the polygons of the shape of the through hole shown in FIG. The correction pattern is extended from the apex pointed in parallel to the long side of the parallelogram. In this embodiment, the mask pattern correction pattern shown in FIG. 6B is longer than the mask pattern correction pattern shown in FIG. This is because since the back surface is doped with boron, the etch rate from the front surface and the etch rate from the back surface are different.
[0048]
In this embodiment, the correction pattern from the front surface is about 210 μm long, the correction pattern from the back surface is about 105 μm long, and the width is about 20 μm. The width of the correction pattern can be set by adding a certain margin to the processing limit.
[0049]
FIG. 6D is an explanatory diagram for comparing the mask pattern shown in FIG. 6B and FIG. 6C with the desired through hole shape shown in FIG. is there. It can be seen that the shape obtained by superimposing both mask patterns and removing the correction pattern parallel to the sides of the parallelogram is the shape of the through hole shown in FIG.
[0050]
It is desirable that the correction pattern pitch, that is, the parallelogram superposition pitch P, be the same as the counter electrode pitch. This is to prevent the remaining portion and the counter electrode from overlapping each other even if the silicon masked by the correction pattern remains. Therefore, this pitch is determined by the processing capability when connecting the counter electrode and the external circuit, and is about 100 μm in this embodiment as described above.
[0051]
Now, after bonding the silicon substrate 2 and the glass substrate 4, a sealing adhesive 30 is applied from the through hole 13 of the silicon substrate 2. Thereby, the vibration chamber 15 can be hermetically sealed.
[0052]
As shown in FIG. 1, the voltage applying means 21 is provided between the bottom wall (vibrating plate) 51 of the silicon substrate 2 and the segment electrode (counter electrode) 18 in response to an external print signal (not shown). Apply drive voltage. One output of the voltage applying means 21 is connected to the terminal portion 20 of each segment electrode 18, and the other output is connected to the common electrode terminal 22 formed on the silicon substrate 2.
[0053]
Since the silicon substrate 2 itself has conductivity, a voltage can be supplied from the common electrode terminal 22 to the common electrode of the bottom wall (vibration plate) 51. Since the silicon substrate 2 has a relatively high electrical resistance, the voltage supplied to the common electrode drops. In order to avoid such a voltage drop, it is necessary to reduce the electrical resistance. If a thin film of a conductive material such as gold is formed on one surface of the silicon substrate 2 by vapor deposition or sputtering, the electrical resistance can be lowered. In this embodiment, anodic bonding is used to connect the silicon substrate 2 and the glass substrate 4, and a conductive film is formed on the flow path forming surface side of the silicon substrate 2.
[0054]
In the ink jet head 1 configured as described above, when the driving voltage from the voltage applying means 21 is applied between the bottom wall (vibrating plate) 51 and the segment electrode (counter electrode) 18, it is charged between the two. An electrostatic force is generated by the electric charge, and the bottom wall (vibration plate) 51 is deflected and displaced toward the segment electrode (counter electrode) 18 side, and the volume of the ink chamber 5 is expanded.
[0055]
When a pulsed voltage is applied, when the charged charge is discharged, the bottom wall (vibrating plate) 51 is returned and displaced from the segment electrode (counter electrode) 18 side by its elastic restoring force, The volume of the ink chamber 5 contracts rapidly. Due to the internal pressure change in the ink chamber 5 that occurs at this time, a part of the ink filling the ink chamber 5 is ejected as an ink droplet from the nozzle hole 8 communicating with the ink chamber.
[0056]
Next, the hermetic sealing of the vibration chamber 15 will be described with reference to FIGS. In order to prevent moisture and dust in the atmosphere from entering during driving, it is necessary to securely seal the vibration chamber 15.
[0057]
FIG. 7 is an enlarged view of the vicinity of the passage 17 in the embodiment of the present invention shown in FIG. FIG. 8 is an enlarged view of the vicinity of the passage 17 of the prototype in the case where the overlapping pitch of the parallelograms of the through holes 13 is 200 μm for comparison with FIG. 7. In FIG. 7 and FIG. 8, the hatched portion means a portion into which the sealing adhesive 30 has entered.
[0058]
In the electrostatic actuator, in order to make the electrostatic force generated between the diaphragm and the segment electrode (counter electrode) that are relatively displaced to be a sufficiently large force, it is desired to reduce the gap (gap length G) as much as possible. In this embodiment, the depth of the concave portion 16 of the glass substrate 3 is set to 0.3 μm, and the thickness of the segment electrode 18 is set to 0.1 μm. Therefore, the gap length G of the vibration chamber 15 is 0.2 μm.
[0059]
In order to hermetically seal the electrostatic actuator having such a shape with the sealing adhesive 30, the sealing adhesive 30 enters from the side of the passage 17 that is open to the atmosphere, and the sealing adhesive 30 is made to enter. Cured. Then, as shown in FIG. 7, the sealing adhesive 30 was able to reliably hermetically seal the vibration chamber 15.
[0060]
On the other hand, the pitch P of the parallelogram of the through holes 13 was set to 200 μm, and the sealing adhesive 30 was similarly penetrated and cured to try to hermetically seal. Then, as shown in FIG. 8, the sealing adhesive 30 did not sufficiently enter the passage 17, and the vibration chamber 15 was not reliably hermetically sealed. When this state was observed in more detail, as shown in FIG. 8, the sealing adhesive 30 took in the bubbles 310 in the vicinity of the discontinuous portion 14 of the through hole 13 of the silicon substrate 2.
[0061]
In this example, Able Stick's Ablebond 342-37, epoxy low-temperature thermosetting type, and a viscosity of 1000 cP to 14000 cP are used as the sealing adhesive 30. The adhesive is cured in the range of room temperature (25 ° C.) to 150 ° C. and is cured in 48 hours to 2 hours. Epoxy resin has good wettability with silicon and borosilicate glass, and is excellent in water vapor gas barrier properties, and thus can be hermetically sealed. When hermetic sealing was performed with this sealing adhesive, air bubbles were reliably infiltrated without taking in bubbles at the discontinuous portions. In addition, the same was applied to the sealing adhesive 30 with Able Bond 342-3 manufactured by Able Stick.
[0062]
In this embodiment, the face eject type inkjet head has been described as an example, but the present invention is not limited to the face eject type. For example, the present invention can be applied to an edge eject type inkjet head having nozzles in the length direction of the ink chamber.
[0063]
(Other embodiments)
The above description is an example in which the present invention is applied to an inkjet head. The present invention can be similarly applied to electrostatic actuators other than inkjet heads. For example, the present invention can be similarly applied to a micromechanical device and a micromirror disclosed in JP-A-7-13007.
[0064]
【The invention's effect】
As described above, in the electrostatic actuator of the present invention, in particular, the ink jet head, the planar shape of the through hole is a planar shape in which continuous parallelograms are superimposed. Thereby, the size of the through hole can be reduced, and an electrostatic actuator and an inkjet head that are easy to produce and inexpensive can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an inkjet head to which the present invention is applied.
FIG. 2 is a perspective view of the inkjet head of FIG.
3 is an exploded perspective view of the ink jet head of FIG. 1. FIG.
FIG. 4 is a plan view of a silicon wafer to which the present invention is applied.
FIG. 5 is a plan view of a silicon wafer showing an example of a conventional example.
6 is an explanatory diagram of a mask pattern for forming a through hole of the ink jet head of FIG. 1. FIG.
FIG. 7 is an enlarged view of the ink jet head in which the vicinity of the passage in FIG. 1 is enlarged.
FIG. 8 is an enlarged view of the ink jet head in which the vicinity of the passage is enlarged when the parallelogram superposition pitch is 200 μm.
[Explanation of symbols]
P Pitch of overlapping parallelograms of through holes 13 Inkjet head 2 Silicon substrate 3 Nozzle plate 4 Glass substrate 5 Ink chamber 6 Common ink chamber 8 Nozzle hole 9 Ink supply path 12 Through hole 13 in nozzle plate 3 Silicon substrate 2 Through hole 14 Discontinuous portion 15 of through hole 13 Vibration chamber 17 Passage 18 Segment electrode 19 Segment electrode wiring portion 20 Segment electrode terminal portion 21 Voltage application means 22 Common electrode terminal portion 30 Sealing adhesive 31 Silicon wafer 32 Silicon substrate 35 Ink chamber 36 Common ink chamber 40 Ink supply hole 42 Common electrode terminal 43 Through hole 51 Bottom wall of ink chamber (common electrode, diaphragm)
101 Silicon wafer 310 Bubble

Claims (13)

(110) An opening having a polygonal shape obtained by superimposing a plurality of parallelograms continuous on a plane, and an opening in which a wiring pattern is disposed; A (110) silicon substrate having a diaphragm displaced by static electricity,
A counter electrode disposed opposite to the diaphragm and conducting to a wiring pattern disposed in the opening;
Driving means for displacing the diaphragm by applying a voltage from the wiring pattern to the diaphragm and the counter electrode;
An electrostatic actuator comprising: 2. The electrostatic actuator according to claim 1, wherein a pitch of overlapping the parallelograms of the openings is substantially the same as a pitch of the wiring pattern. The electrostatic actuator according to claim 1, further comprising a sealing member for hermetically sealing a vibration chamber formed by the vibration plate and the counter electrode. The electrostatic actuator according to claim 3, wherein the sealing member is an epoxy-based low-temperature thermosetting type and has a viscosity of 1000 cP to 14000 cP. (110) An opening having a polygonal shape obtained by superimposing a plurality of parallelograms continuous on a plane, and an opening in which a wiring pattern is disposed; A (110) silicon substrate having a diaphragm displaced by static electricity,
A counter electrode disposed opposite to the diaphragm and conducting to a wiring pattern disposed in the opening;
Driving means for applying a voltage to the wiring pattern, generating static electricity between the diaphragm and the counter electrode, and displacing the diaphragm;
A sealing member that hermetically seals between the diaphragm and the counter electrode, and provides an ink chamber that varies in pressure due to displacement of the diaphragm;
An ink nozzle that communicates with the ink chamber and discharges ink droplets accumulated in the ink chamber due to pressure fluctuations in the ink chamber;
An ink jet head comprising: The vibration plate, the ink chamber, and the ink nozzle are partitioned and provided in plurality on the (110) silicon substrate,
The inkjet head according to claim 5, wherein a plurality of wiring patterns that are electrically connected to the counter electrodes of the plurality of diaphragms are disposed in the opening. The inkjet head according to claim 6, wherein the pitch of the parallelograms of the openings is substantially the same as the pitch of the wiring pattern. (110) In a (110) silicon substrate, characterized by having a polygonal opening formed by superimposing a plurality of parallelograms continuous in a plane,
The (110) silicon substrate according to claim 6, wherein a pitch of overlapping the parallelograms of the openings is equal to or less than a thickness of the (110) silicon substrate. 9. The (110) silicon substrate according to claim 8, wherein one of the inner angles of the parallelogram is 70.19 degrees. Of the vertices of a polygon whose inner angle is a 70.19 degree parallelogram superimposed in parallel with its long side, the vertex whose inner angle is 289.81 degree is changed to the long side of the parallelogram. A mask for anisotropic etching of a (110) silicon substrate, comprising a mask pattern having a shape in which a correction pattern is extended in parallel. Of the vertices of a polygon whose inner angle is a 70.19 degree parallelogram superimposed in parallel with its long side, the vertex whose inner angle is 289.81 degree is changed to the long side of the parallelogram. Masking the (110) plane of the (110) silicon wafer with a mask pattern having a shape in which the correction pattern is extended in parallel;
Anisotropically etching the masked (110) silicon wafer;
(110) A method for producing a silicon substrate, comprising: 12. The method of manufacturing a (110) silicon substrate according to claim 11, wherein the length of the correction pattern is set based on an etching rate of the anisotropic etching. Two types of lengths of the correction pattern of the mask pattern are set based on the etch rate on both sides of the (110) silicon wafer, and both sides of the (110) silicon wafer are masked with the two types of mask patterns, respectively.
12. The method of manufacturing a (110) silicon substrate according to claim 11, wherein the (110) silicon wafer is anisotropically etched from both sides.

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