JP2006223066A - Method for manufacturing electrostatic actuator, method for manufacturing liquid drop ejection head, and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a high density nozzle, and to bond a glass substrate and a cavity substrate with a high yield without causing the cracking of the cavity substrate even if a thin silicon cavity substrate is used. <P>SOLUTION: In this method for manufacturing an electrostatic actuator comprising an electrode 8 and a diaphragm 4 opposing the electrode through a gap and deforming the diaphragm by applying a voltage between the diaphragm and the electrode, a cavity substrate or a silicon substrate 2 provided with an orientation flat 19b serving as a reference line for alignment and on which the diaphragm is formed, and a glass substrate 1 having an outside diameter larger than that of the silicon substrate provided with an orientation flat 19a serving as a reference line for alignment and on which the electrode is formed are stacked so that the reference lines are directed in the same direction and then bonded while being aligned so that the outer circumference of the silicon substrate is located inside of outer circumference of the glass substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for manufacturing an electrostatic actuator, a method for manufacturing a droplet discharge head, and a method for manufacturing a device, and more particularly, a method for manufacturing an electrostatic actuator that can be manufactured at high density, low cost, and high yield, and manufacturing the electrostatic actuator. The present invention relates to a device manufacturing method including a manufacturing method of a droplet discharge head such as an electrostatic drive type inkjet head to which the method is applied and a manufacturing method of an electrostatic actuator.

There is a need for a manufacturing method that can be manufactured with high density, low cost, and high yield in an electrostatically driven droplet discharge head.
As the nozzle density increases, it is necessary to use a thin silicon substrate of 100 μm or less in order to prevent crosstalk. Furthermore, in order to reduce the cost, it is necessary to establish a process that can handle a large-diameter substrate.
The conventional silicon cavity substrate, silicon nozzle substrate, and glass substrate are manufactured separately and bonded together, and the thickness and size of the silicon cavity substrate and nozzle substrate that can be handled are also limited from the viewpoint of handling. was there.
Therefore, in order to increase the density of the nozzle and use a thin silicon cavity substrate or nozzle substrate, in a conventional inkjet head manufacturing method, after bonding a thin silicon cavity substrate to a thick glass substrate, the silicon Processing each part of the cavity substrate,
Finally, the nozzle substrate is bonded to the cavity substrate with an adhesive (for example, see Patent Document 1).
JP-A-11-993 (2nd page, FIG. 3)

In such a conventional inkjet head manufacturing method, when the silicon cavity substrate and the glass substrate have the same diameter, even if an attempt is made to cut the cavity substrate having the same diameter as the glass substrate, variations due to manufacturing tolerances occur. When they are overlapped, the cavity substrate may protrude from the outer periphery of the glass substrate, and it is difficult to match the outer periphery of both substrates.
Therefore, when the cavity substrate is bonded to the glass substrate, a part of the outer periphery of the cavity substrate is not bonded to the glass substrate, and when the silicon substrate is ground and polished in this state, the portion of the cavity substrate that protrudes from the glass substrate Has cracked, and the cavity substrate is cracked from the cracked portion, leading to cracking of the cavity substrate, thereby reducing the yield.

Therefore, the present invention has been made to solve such problems, and even if a high-density nozzle is used and a thin silicon cavity substrate or nozzle substrate is used, the silicon cavity substrate does not break. An object of the present invention is to obtain a manufacturing method of an electrostatic actuator such as an inkjet head, a manufacturing method of a droplet discharge head, and a manufacturing method of a device, which can bond a glass substrate, a cavity substrate, and a nozzle substrate with high yield.

A method for manufacturing an electrostatic actuator according to the present invention includes an electrode and a diaphragm facing the electrode with a gap, and applies a voltage between the diaphragm and the electrode to deform the diaphragm. In the method of manufacturing an electroactuator, a reference line for alignment is provided, the silicon substrate on which the diaphragm is to be formed, a reference line for alignment, the electrode is formed, A glass substrate having an outer diameter larger than the outer diameter of the silicon substrate is overlaid so that the respective reference lines are in substantially the same direction, and aligned so that the outer periphery of the silicon substrate is inside the outer periphery of the glass substrate. It is characterized by being joined.

According to the present invention, a silicon substrate on which a reference line for alignment is formed and the diaphragm is to be formed, a reference line for alignment is formed, the electrode is formed, and the silicon is formed. Since a glass substrate having an outer diameter larger than the outer diameter of the substrate is overlapped so that the respective reference lines are in substantially the same direction, a reference line that is a positioning reference for patterning provided on the glass substrate and the silicon substrate is set. It can also be used as an alignment reference, and the silicon substrate can be superimposed on the glass substrate without angular deviation, and then the silicon substrate is aligned and bonded so that the outer periphery of the glass substrate is inside the outer periphery of the glass substrate. At the time of grinding, etc., cracks are less likely to occur at the periphery of the silicon substrate, and there is an effect that the yield is improved at high density and low cost.

In the method for manufacturing an electrostatic actuator according to the present invention, the glass substrate and the silicon substrate are bonded by anodic bonding.
Thus, by anodic bonding the glass substrate and the silicon substrate, it becomes possible to easily and reliably bond the glass substrate and the silicon substrate.

In the method for manufacturing an electrostatic actuator according to the present invention, the reference line included in the glass substrate and the silicon substrate is an orientation flat or an elongated groove.
In this way, the reference line can be easily produced by using the orientation flat or elongated groove as the reference line included in the glass substrate and the silicon substrate.

In the method for manufacturing an electrostatic actuator according to the present invention, alignment between the glass substrate and the silicon substrate is performed by using an alignment mark provided on the glass substrate and an alignment mark provided on the silicon substrate.
As described above, alignment between the glass substrate and the silicon substrate is performed by using the alignment mark provided on the glass substrate and the alignment mark provided on the silicon substrate to align the glass substrate and the silicon substrate. Can be performed by a simple operation of matching both alignment marks.

In the electrostatic actuator manufacturing method of the present invention, when the alignment marks provided on the glass substrate are overlapped so that the outer periphery of the silicon substrate is inside the outer periphery of the glass substrate, The alignment mark provided on the glass substrate is positioned so as to be inside the outer periphery of the silicon substrate.
In this way, the alignment mark provided on the glass substrate is the same as the alignment mark provided on the glass substrate when the two substrates are overlaid so that the outer periphery of the silicon substrate is inside the outer periphery of the glass substrate. By positioning the silicon substrate so as to be inside the outer periphery of the silicon substrate, when the silicon substrate is superimposed on the glass substrate, the alignment mark of the glass substrate can be reliably used for the alignment of the silicon substrate.

A method for manufacturing a droplet discharge head according to the present invention includes joining a nozzle substrate having a plurality of nozzles to a silicon substrate of an electrostatic actuator manufactured by any one of the above-described electrostatic actuator manufacturing methods. And a silicon substrate, a discharge chamber communicating with each of the nozzles is formed, and a droplet discharge head for discharging droplets from the nozzles by deformation of the vibration plate is manufactured.
A nozzle substrate having a plurality of nozzles is bonded to the silicon substrate of the electrostatic actuator manufactured by any one of the above-described electrostatic actuator manufacturing methods, and each nozzle is communicated between the nozzle substrate and the silicon substrate. If a droplet discharge head that forms a discharge chamber and discharges droplets from the nozzle by deformation of the vibration plate is manufactured, the droplet discharge head can be manufactured with high density and low cost and high yield.

A device manufacturing method according to the present invention includes any one of the above-described electrostatic actuator manufacturing methods.
By including any of the above-described methods for manufacturing an electrostatic actuator, a device can be manufactured with high density and low cost and high yield.

1 is an exploded perspective view showing an outline of the configuration of a droplet discharge head manufactured by the method of manufacturing a droplet discharge head according to Embodiment 1 of the present invention, and FIG. 2 is an outline of the configuration of the droplet discharge head. FIG. 3 is a cross-sectional view showing an outline of a junction state of equipotential points of the droplet discharge head, FIG. 4 is a plan view showing an outline of a glass substrate of the droplet discharge head, and FIG. FIG. 6 is a cross-sectional view showing the steps of the manufacturing method of the droplet discharge head, FIG. 6 is a cross-sectional view showing the steps of the manufacturing method of the droplet discharge head, and FIG. FIG. 8 is a plan view showing a state in which a glass substrate and a cavity substrate are overlaid using an orientation flat in a step of the manufacturing method of the droplet discharge head, FIG. 9 shows the glass in the manufacturing method of the droplet discharge head. It is an explanatory view showing a specific various shapes of the alignment marks of the plate and the cavity substrate.
As shown in FIG. 1, a droplet discharge head 10 of Embodiment 1 includes a glass substrate 1 as a first substrate having electrodes 8 and a silicon cavity substrate 2 as a second substrate having a vibration plate portion 4. And a nozzle substrate 3 as a third substrate having the nozzles 12 has a three-layer structure.

As shown in FIG. 2, the droplet discharge head 10 supplies ink as liquid filled in the discharge chamber 5 facing the vibration plate portion 4 to the vibration plate portion 4 and the vibration plate portion 4 at a predetermined interval. Pressure is applied by an electrostatic actuator 20 composed of electrodes 8 arranged to face each other at G, and liquid ink is ejected from the nozzle 13 as droplets.
Accordingly, the ink jet head 10 will be described below. As shown in FIG. 1, in the inkjet head 10, the discharge chamber 5 communicating with the nozzle 13 and the electrostatic actuator 20 for pressurizing the ink filled in the discharge chamber 5 correspond to the plurality of nozzles 13. A plurality of sections are formed on each substrate.

The glass substrate 1 as the first substrate uses borosilicate heat-resistant hard glass having a thickness of about 1 mm. As shown in FIG. 1, the glass substrate 1 has an electrode 8 and a terminal portion 11 connected thereto.
Is formed by depositing ITO (Indium Tin Oxide) on the bottom surface of the recess 9 to a thickness of about 0.1 μm by sputtering.
Further, when the glass substrate 1 and the silicon cavity substrate 2 are anodic bonded later, the diaphragm 4 and the electrode 8 are prevented in order to prevent discharge between the diaphragm 4 and the electrode 8 made of ITO.
An equipotential point 25 is formed on the joining surface of the glass substrate 1 in parallel with the electrode 8 by using the formed ITO.

The cavity substrate 2 as the second substrate is a single crystal silicon substrate having a plane orientation (110) of about 100 μm thickness. As shown in FIGS. 1 to 3, the cavity substrate 2 includes a discharge chamber 5 having a vibration plate portion 4 as one component surface and a reservoir 7 that is a common ink cavity for supplying ink to the discharge chamber 5. It is formed by isotropic etching.
In addition, the reservoir 7 is partially perforated so as to communicate with an ink supply hole 13 provided in the glass substrate 1 in order to supply ink from the outside.
Then, as shown in FIG. 2, the glass substrate 1 and the silicon cavity substrate 2 are joined together, and a gap formed between the vibration plate portion 4 and the electrode 8 disposed to face the diaphragm portion 4 with a predetermined gap G is obtained. The portion is sealed with a sealant 26 to form the vibration chamber 18 in a sealed state.
At this time, in order to spread the sealing agent 26 to each vibration chamber 18, the sealing groove 23 is anisotropically formed on the bonding surface of the cavity substrate 2 so as to communicate with the sealing agent injection hole 24 provided in the glass substrate 1. Formed by reactive etching.

The nozzle substrate 3 as the third substrate is a thin silicon plate having a thickness of approximately 180 μm. As shown in FIGS. 1 and 2, a plurality of nozzles 13 communicating with the discharge chamber 5 are formed on the nozzle substrate 3.
A concave portion 6a for forming an orifice 6 which is a flow path for supplying ink from the reservoir 7 to the discharge chamber 5 is formed by anisotropic etching.
In addition, diaphragms 14 are formed at both ends of the nozzle substrate 3 so as to face the reservoir 7 formed on the cavity substrate 2 and suppress pressure fluctuation in the reservoir 7. This diaphragm 14 is formed by processing a part of the nozzle substrate 3 thinly, for example, by etching.
The nozzle substrate 3 can be made of a borosilicate hard glass, a steel plate such as stainless steel, a resin plate such as plastic, or the like as the glass substrate 1 as the first substrate.

In the inkjet head 10 of the first embodiment, the boron dope layer 4a is formed in advance on the bonding surface side of the cavity substrate 2 so that the vibration plate portion 4 has a desired thickness.
The boron doped layer 4a has a boron doped region having a high concentration (about 5 × 10 ¹⁹ atoms · cm ⁻³ or more). When the silicon cavity substrate 2 is anisotropically etched with an alkaline aqueous solution, the boron doped layer 4a is etched. Stops. The diaphragm 4 is formed using this etching stop technique.
In addition, when the electrostatic actuator 20 is driven, an insulating film 14 is formed on the bonding surface of the cavity substrate 2 so that the vibration plate portion 4 and the electrode 8 are in contact with each other and are not electrically short-circuited.
The insulating film 14 is formed by depositing TEOS (Tetraethyl orthosilicate Tetraethoxysilane) to a thickness of about 0.1 μm by plasma CVD (Chemical Vapor Deposition).

Therefore, in order to bring the equipotential point 25 described above into contact with the boron doped layer 4a and make it equipotential with the electrode 8, the glass substrate 1 on which the electrode 8 and the equipotential point 25 are formed as shown in FIG.
Before the cavity substrate 2 on which the diaphragm portion 4 is formed is bonded, the insulating film 15 formed on the bonding surface of the cavity substrate 2 is partially so that the equipotential point 25 can be in contact with the boron doped layer 4a. Etched away.
FIG. 4 is a plan view schematically showing the glass substrate 1 as the first substrate. As shown in FIG. 4, the equipotential point 25 is formed on the bonding surface so as to be parallel to the electrode 8 of the glass substrate 1. The equipotential point 25 is 1 after the glass substrate 1, the cavity substrate 2 and the nozzle substrate 3 are bonded.
The ink jet heads 10 are connected to the terminal portions 11 on the right side of the dicing line 33 that is cut to take out the two ink jet heads 10. Therefore, after cutting, the equipotential point 25 is separated from the electrode 8,
The plurality of electrodes 8 are also divided.

As shown in FIG. 2, the method for driving the inkjet head 10 as described above includes an oscillation circuit 22 between the terminal portion 11 of the electrode 8 provided on the glass substrate 1 and the common electrode 21 provided on the cavity substrate 2. Connect. Then, a voltage pulse of a drive voltage of 30 V is applied from the oscillation circuit 22 between the electrode 8 and the common electrode 21 at 24 kHz, for example. Then, when the electrode 8 is positively charged, the diaphragm 4 facing the electrode 8 is negatively charged and the diaphragm 4 is attracted to the electrode 8 by electrostatic force.
When the application of the voltage pulse is released and the accumulated electric charge is discharged, the diaphragm portion 4 returns to the original position. The ink filled in the discharge chamber 5 is pressurized by the displacement of the vibration plate portion 4 and is discharged as droplets from the nozzle 13.

The ink used is prepared by dissolving or dispersing a surfactant such as ethylene glycol and a dye or pigment in a main solvent such as water or alcohol. Furthermore, if a heater or the like is attached to the inkjet head 10, hot melt type ink can also be used.
The ink jet head 10 according to the first embodiment is a face eject method, but may be an edge eject method in which nozzles 13 for discharging ink are opened on the end surface of the cavity substrate 2 or the nozzle substrate 3.

As described above, in the first embodiment, the electrostatic actuator is mainly configured by the diaphragm portion 4 and the electrode 8. In the first embodiment, the electrostatic drive type droplet discharge head 1 is shown as an example to which the manufacturing method of the electrostatic actuator according to the present invention is applied. However, the manufacture of the droplet discharge head according to the first embodiment is shown. The method is an optical MEMS (Micro Electro Mechanical) such as a mirror device.
It can also be applied to (System) devices.

Next, the manufacturing method of the inkjet head 10 is demonstrated based on FIGS.
FIG. 5A shows a process of forming the electrode 8, the equipotential point 25, and the recess 16 as an alignment mark on the glass substrate 1.
The glass substrate 1 is a borosilicate hard glass having a thickness of 1 mm. The outer diameter of the glass substrate 1 is about 5 mm larger than the outer diameter of the silicon cavity substrate 2. Then, one orientation flat 19a serving as a reference line for positioning reference for patterning is formed and used as a reference for substrate alignment. The length of the orientation flat 19a of the glass substrate 1 is the same as the orientation flat 19b of the cavity substrate 2 described later.
Although the orientation flat is formed as a reference line on the glass substrate 1 and the cavity substrate 2, for example, other than the orientation flat, a thin cutting groove formed on the surface of the glass substrate 1 and the cavity substrate 2 may be used as the reference line.
The alignment mark 17a on the glass substrate 1 is positioned on the glass substrate 1 on the cavity substrate 2
Is overlapped with the orientation flat 19 of the glass substrate 1 so that the orientation flat 19b of the cavity substrate 2 is in the same direction, the outer diameter of the cavity substrate 2 from the center when the center of the glass substrate 1 is the center of coordinates. Shorter than the outer periphery of the cavity substrate 2.

And the recessed part 9 and the recessed part 16 of the glass substrate 1 are etched so that it may become a depth of about 0.3 micrometer. The etching method is performed by masking the surface of the glass substrate 1 other than the etching surface with Cr and immersing the glass substrate 1 in an aqueous ammonium fluoride solution at room temperature.
Then, an ITO film to be the electrode 8 is formed to a thickness of about 0.1 μm by sputtering on the bonding surface 1a where the recess 9 and the recess 16 are formed, and the bottom surface of the corresponding recess 9 is formed by photolithography. And an equipotential point 25 is formed on the bonding surface 1a.
The shape of the equipotential point 25 is linear in the first embodiment, but may be any shape as long as it can be in contact with the boron doped layer 4a.
Further, the glass substrate 1 is provided with the ink supply holes 13 and the sealant injection holes 24 by a cutting method using a diamond drill or the like from the bonding surface 1a side.

FIG. 5B is a process of forming a recess 16 as an alignment mark on the cavity substrate 2 on the surface opposite to the bonding surface 2 a with the glass substrate 1.
The cavity substrate 2 is obtained by mirror polishing both surfaces of a single crystal silicon substrate having a plane orientation (110) having a low oxygen concentration, and has a thickness of about 525 μm.
A first orientation flat 19b and a second orientation flat (not shown) are formed on the cavity substrate 2. The orientation flat 19a of the glass substrate 1 when the first orientation flat 19b is overlapped with the glass substrate 1 is used as a positioning reference for patterning. The crystal orientation is discriminated with the second orientation flat. The length of the first orientation flat 19b of the cavity substrate 2 is the same as that of the orientation flat 19a of the glass substrate 1. A cavity substrate 2 having an outer diameter smaller than that of the glass substrate 1 by about 5 mm is prepared.

By leaving the cavity substrate 2 in a water vapor atmosphere at a temperature of 1075 ° C. for 4 hours, a silicon oxide film 27 having a thickness of about 1 μm is formed on the surface.
Then, a photoresist is applied on both surfaces, and the silicon oxide film 27 is immersed and etched in an aqueous hydrofluoric acid solution by a photolithography method to form a pattern corresponding to the recess 16.
The pattern is formed at a position on the assumption that the outer periphery of the cavity substrate 2 is inside the outer periphery of the glass substrate 1 when the cavity substrate 2 and the glass substrate 1 are overlapped in a later step. Specifically, when the centers of the cavity substrate 2 and the glass substrate 1 are the center of coordinates, the alignment mark 17a on the glass substrate 1 and the alignment mark 17b on the cavity substrate 2 are made to coincide with each other to form a pattern. To do.

FIG. 5C shows a step of etching the recess 16 as an alignment mark to a depth of about 10 μm using the pattern of the silicon oxide film 27 formed on the cavity substrate 2 in FIG. 5B as a mask.
In this etching method, the cavity substrate 2 is immersed in a 35 wt% potassium hydroxide aqueous solution to perform anisotropic etching.
FIG. 5D shows a step of forming the sealing groove 23 on the bonding surface 2a of the cavity substrate 2 with the glass substrate 1 with reference to the concave portion 16 as the alignment mark formed in FIG.
For the sealing groove 23, a photoresist is applied to the bonding surface 2a and the opposite surface, and the silicon oxide film 27 is first etched using a hydrofluoric acid aqueous solution by a photolithography method. Next, the cavity substrate 2 is immersed in a 35 wt% potassium hydroxide aqueous solution and anisotropically etched to a depth of about 40 μm.

FIG. 5E shows a step of removing the silicon oxide films 27 formed on both surfaces of the cavity substrate 2.
In the cavity substrate 2, the boron doped layer 4a is formed in the next step. If the silicon oxide film 27 is present on the surface at this time, boron is difficult to diffuse, and is removed. In this case, the cavity substrate 2 is immersed and removed in a hydrofluoric acid aqueous solution.
FIG. 5F shows a step of forming the boron doped layer 4 a on the cavity substrate 2.
The cavity substrate 2 is first cleaned by removing and removing fine foreign substances and metals adhering to the bonding surface 2a forming the boron doped layer 4a.
In this case, cleaning with a mixed solution of ammonia water and hydrogen peroxide solution and cleaning with a mixed solution of hydrochloric acid and hydrogen peroxide solution are performed.
Next, the cleaned cavity substrate 2 is set in a diffusion furnace having a solid diffusion source mainly composed of B ₂ O _{3 so} that the bonding surface 2a faces the diffusion source, and the inside of the furnace is made a nitrogen atmosphere. Temperature 1
Hold at 050 ° C. for 7 hours. As a result, boron is diffused into the bonding surface 2a of the cavity substrate 2 to form a boron doped layer 4a as shown in FIG.

Thus, it is preferable that the temperature when the cavity substrate 2 is introduced into the diffusion furnace and when the cavity substrate 2 is removed is 800 ° C. Moreover, it can prevent that an oxygen defect generate | occur | produces by passing rapidly the temperature range of 600-800 degreeC which an oxygen defect tends to produce in the cavity board | substrate 2. FIG. In addition, when an oxygen defect arises, the hole may open in the part.
In addition, when the cavity substrate 2 is anisotropically etched, an etching abnormality is likely to occur at the oxygen defect portion. Further, a boron compound (SiB ₆ ) formed on the surface of the boron doped layer 4a.
It is preferable to remove (not shown). This boron compound is known to inhibit the adhesion of the insulating film 14 formed in the next step.
Therefore, the cavity substrate 2 is heated to 600 ° C. in an oxygen and water vapor atmosphere and left for one and a half hours to oxidize the boron compound, and it is removed as B ₂ O ₃ + SiO ₂ by etching with a hydrofluoric acid aqueous solution.

FIG. 5G shows a step of forming the insulating film 15 on the surface of the boron doped layer 4a.
The insulating film 15 is formed by forming TEOS to a thickness of approximately 0.1 μm by plasma CVD. The film forming conditions in this case are, for example, a temperature of 360 ° C., a high frequency output of 250 W, and a pressure of 66.
7 Pa (0.5 Torr), TEOS gas flow rate 100 cm ³ / min (100 sccm), oxygen flow rate 1000 cm ³ / min (1000 sccm).
FIG. 5H shows a step of removing a part of the insulating film 15 by etching so that the equipotential point 25 formed on the glass substrate 1 can be in contact with the boron doped layer 4a.
A photoresist is applied to the surface of the insulating film 15, patterned, and etched with a hydrofluoric acid aqueous solution to form the opening 15a. FIG. 5H shows a cross section of the cavity substrate 2 from which a part of the insulating film 15 has been removed at a position corresponding to the equipotential point 25.

FIG. 5I shows a bonding process in which the glass substrate 1 and the cavity substrate 2 are anodic bonded.
This bonding step is performed by the orientation flat 19a of the glass substrate 1 and the first orientation flat 1 of the cavity substrate 2.
9b and an alignment step of aligning the glass substrate 1 and the cavity substrate 2 using the alignment mark 17a of the glass substrate 1 and the alignment mark 17b of the cavity substrate 2.
In the alignment step, first, the orientation flat 19a of the glass substrate 1 and the first of the cavity substrate 2 are used.
The substrates are stacked so that the orientation flat 19b is in the same direction. At this time, the cavity substrate 2 superimposed on the glass substrate 1 has no crystal orientation angular deviation, and the outer diameter of the cavity substrate 2 is about 5 mm smaller than the outer diameter of the glass substrate 1, so 7 and 8
As shown.
Therefore, next, the alignment mark 17a of the glass substrate 1 and the alignment mark 17b of the cavity substrate 2 are adjusted and aligned. If the alignment marks of both coincide, the pattern of the glass substrate 1 and the pattern of the cavity substrate 2 also coincide and the alignment process is completed.

The specific shapes of the alignment marks 17a and 17b on the glass substrate 1 and the cavity substrate 2 are as shown in FIG.
Both of the alignment marks 17a and 17b shown in FIG. 9A are parallelograms, and the alignment mark shown in FIG. 9B is the alignment mark 17a of the glass substrate 1.
Is a parallelogram frame having two legs on one end side of the frame, and the alignment mark 17b of the cavity substrate 2 entering the inside of the frame of the alignment mark 17a of the glass substrate 1, and the alignment mark 17a It is formed of two parallelograms that enter the legs.

Thus, when the alignment is completed in the alignment step, anodic bonding between the glass substrate 1 and the cavity substrate 2 is started.
In the anodic bonding method, the glass substrate 1 and the cavity substrate 2 that have been aligned in the alignment step are heated at a temperature of 360 ° C. for 30 minutes, and then the glass substrate 1 is used as a negative electrode, the cavity substrate 2 is used as a positive electrode, and a voltage of 800 V is applied. Apply for a minute to join. At this time, if the voltage boosting rate is too high, a large current flows through the equipotential point 25 and the ITO wiring may be damaged. Therefore, it is preferable to perform the bonding so that the current does not exceed 10 mA.

In FIG. 5 (j), the surface of the cavity substrate 2 is approximately 110 μm thick.
It is the process of grinding so that it becomes.
Further, since a work-affected layer having a brittle composition appears on the surface of the cavity substrate 2 by grinding, this work-affected layer is etched by about 10 μm with a 32 wt% potassium hydroxide aqueous solution.
As a result, the thickness of the cavity substrate 2 becomes approximately 100 μm. At this time, etching is performed on the surface opposite to the bonding surface of the glass substrate 1 while protecting with a jig so that the chemical solution does not enter the gap from the ink supply hole 13 and the sealant injection hole 24.

FIG. 6K shows a step of forming a TEOS film 28 on the surface of the cavity substrate 2 from which the work-affected layer has been removed.
The TEOS film 28 is used as an etching mask when the cavity substrate 2 is anisotropically etched in the next step. The conditions for forming the TEOS film 28 are, for example, a temperature of 360 ° C. and a high frequency output of 700 W.
, Pressure 33.3 Pa (0.25 Torr), TEOS gas flow rate 100 cm ³ / min (100
sccm), and an oxygen flow rate of 1000 cm ³ / min (1000 sccm). Thereby, a TEOS film 28 having a thickness of about 1.5 μm is formed.

6 (l) shows that the cavity plate 2 and the recess 29 constituting the discharge chamber 5, the recess 30 constituting the reservoir 7, and the recess 31 for forming the electrode outlet 32 are formed by anisotropic etching on the cavity substrate 2. FIG. It is a process of forming. In this case, it is called a cavity etching process.
First, a resist pattern corresponding to each of the recesses 29, 30, 31 is formed on the surface of the TEOS film 28 by photolithography. Then, the TEOS film 28 is etched with a hydrofluoric acid aqueous solution to form an etching mask pattern.
At this time, the TEOS film 28 has a thickness of about 0 on the surface of the TEOS film 28 corresponding to the recess 30.
. Etch to leave 3 μm.
In this step, the resist pattern is formed and etched on the surface opposite to the bonding surface of the glass substrate 1 while protecting with a jig so that the chemical solution does not enter the gap from the ink supply hole 13 and the sealing injection hole 24. I do.

Next, the bonded glass substrate 1 and cavity substrate 2 are immersed in a 35 wt% aqueous potassium hydroxide solution, and anisotropic etching is performed so that the thickness of the bottom surface of the recess 29 becomes approximately 10 μm. Then, the boron dope layer 4 is immersed in a 3 wt% potassium hydroxide aqueous solution.
Anisotropic etching is performed until the etching stops at a.
By performing two-stage anisotropic etching with different concentrations as described above, the vibration plate portion 4 having an accuracy with a thickness of 0.8 ± 0.05 μm or less can be formed while suppressing etching surface roughness. Further, since the TEOS film 28 is left by 0.3 μm, the recess 30 is formed while anisotropic etching starts late and leaves a thickness of approximately 40 μm.
By ensuring the thickness accuracy of the diaphragm 4, the characteristics as the electrostatic actuator 20 are stabilized. That is, the ink ejection characteristics of the inkjet head 10 can be stabilized. In this step, etching is performed on the surface opposite to the bonding surface of the glass substrate 1 while protecting with a jig so that the chemical solution does not enter the gap from the ink supply hole 13 and the sealant injection hole 24.

FIG. 6 (m) is a process for forming the electrode outlet 32 in the cavity substrate 2.
First, the bonded glass substrate 1 and cavity substrate 2 are immersed in a hydrofluoric acid aqueous solution, and the TEOS film 28 on the cavity substrate 2 is removed by etching. At this time, etching is performed on the surface opposite to the bonding surface of the glass substrate 1 while protecting with a jig so that the chemical solution does not enter the gap from the ink supply hole 13 and the sealant injection hole 24.
Next, portions other than the portion corresponding to the electrode outlet 32 are masked and opened by RIE dry etching. The dry etching conditions at this time are, for example, RF power 200 W
50 at a pressure of 40 Pa (0.3 Torr) and a CF4 flow rate of 30 cm3 / min (30 sccm)
Etch for minutes.

FIG. 6N shows a process of forming the common electrode 21 on the cavity substrate 2. In addition, the vibration chamber 18 is hermetically sealed using the sealant 26.
First, the cavity part opened to the bonding surface 2b of the cavity substrate 2 is masked, and chromium-gold (Cr-Au) or platinum (Pt) is formed by sputtering to form the common electrode 21.
Next, the sealing agent 26 is injected from the sealing agent injection hole 24, and the sealing agent 26 is filled into each vibration chamber 18 in which the vibration plate portion 4 and the electrode 8 are disposed to face each other through the sealing groove 23. Thus, each vibration chamber 18 is
Is hermetically sealed.

FIG. 6O shows a bonding process in which the silicon nozzle substrate 3 is bonded to the bonding surface 2 b of the silicon cavity substrate 2.
In the nozzle substrate 3, recesses that will form the plurality of nozzles 13 and the orifices 6 are formed in advance by anisotropic etching. The nozzle 13 and the recess can also be formed by dry etching.
Further, before joining the nozzle substrate 3 to the cavity substrate 2, a hole communicating with the ink supply hole 13 is formed in the bottom surface of the recess 30 serving as the reservoir 7 by cutting or laser.
The cavity substrate 2 and the nozzle substrate 3 are bonded using a thermosetting resin such as an epoxy resin.

The silicon nozzle substrate 3 having the same diameter as the silicon cavity substrate 2 is used. Also in this case, the alignment mark 17b formed on the bonding surface of the cavity substrate 2 is used.
Correspondingly, an alignment mark (not shown) is formed on the surface opposite to the bonding surface of the nozzle substrate 3 by anisotropic etching, and the cavity substrate 2 and the nozzle substrate 3 are aligned. (Not shown).
If the nozzle substrate 3 has the first orientation flat and the second orientation flat, the alignment is easy.
In addition, since both the cavity substrate 2 and the nozzle substrate 3 are formed of silicon, there is some variation in size even if both have the same diameter, and either the cavity substrate 2 or the nozzle substrate 3 when bonded by an adhesive. Although there are cases where the outer periphery of the metal sticks out, there will be no problems such as cracking since grinding or polishing will not be performed after joining.

FIG. 6 (p) shows a cutting process by dicing.
The method for manufacturing the inkjet head 10 according to the first embodiment uses wafer-like substrates (glass substrate 1, cavity substrate 2, nozzle substrate 3), and includes electrostatic actuators 20 corresponding to a plurality of nozzles 13. As a unit, a formation region in which a plurality of inkjet heads 10 are formed is partitioned and arranged in the wafer.
Therefore, as shown in FIG. 6 (p), the ink jet head 10 is taken out by cutting along the dicing line 33 (see FIG. 3). The manufacturing process of the inkjet head 10 is completed through the above steps. Needless to say, there is a mounting process for connecting the oscillation circuit 22 (see FIG. 2) and an assembly process for incorporating the circuit into a recording apparatus such as a printer.
In the first embodiment, an example in which the glass substrate 1 has a slightly larger diameter than the cavity substrate 2 is described. However, the glass substrate 1 is several times larger than the cavity substrate 2 and If the large glass substrate 1 is provided with one large orientation flat and a plurality of alignment marks corresponding to the plurality of cavity substrates 2, it goes without saying that the manufacturing method of the first embodiment can be applied.

Embodiment 2. FIG.
FIG. 10 is a perspective view showing an example of a droplet discharge device equipped with the droplet discharge head shown in the first embodiment.
A droplet discharge device 100 shown in FIG. 10 is a general inkjet printer.
Since the liquid droplet ejection head 1 shown in the first embodiment has high ejection stability and durability because water vapor does not enter the gap G between the vibration plate portion 4 and the electrode 8, the liquid is excellent in ejection performance and durability. The droplet discharge device 100 can be obtained.
In addition to the ink jet printer shown in FIG. 10, the liquid droplet ejection head 1 shown in the first embodiment can be used for various manufacturing of liquid crystal display color filters and organic EL by changing various liquid drops.
The present invention can also be applied to formation of a light emitting portion of a display device, discharge of a biological liquid, and the like.

Embodiment 3 FIG.
FIG. 11 is a perspective view of a principal part showing an example of a device equipped with the electrostatic actuator according to the present invention. A device 200 shown in FIG. 11 is a mirror device used as a laser scan mirror for an optical switch or a laser printer.
In the device 200 according to the third embodiment, a drive unit 202, a hinge 20 and a drive substrate 201 are provided.
3. A mirror 204 is formed. In addition, the electrode substrate 2 bonded to the drive substrate 201
In 05, a counter electrode 206 made of ITO or the like is formed. The drive substrate 201 corresponds to the cavity substrate 2 of the droplet discharge head 1 according to the first embodiment, and the drive unit corresponds to the vibration plate unit 4.

In the device 200 illustrated in FIG. 11, the drive unit 202 swings when a voltage is applied between the drive unit 202 and the counter electrode 206. As a result, the hinge 203 is twisted and the force is transmitted to the mirror 204, whereby the mirror 204 changes its angle. As described above, in the third embodiment, the electrostatic actuator is mainly configured by the drive unit 202, the hinge 203, the mirror 204, and the counter electrode 206.
Also in the device 200 according to the third embodiment, a passivation film (not shown in FIG. 11) is formed on the electrode substrate 205, and the counter electrode 206 is formed on the passivation film, thereby blocking water vapor and the like. The driving stability of the unit 202 and the mirror 204 can be improved. Note that the device 200 shown in FIG. 11 is generally vacuum-sealed by packaging (not shown) to be shut off from the outside air.

In the first embodiment, a manufacturing method of a droplet discharge head is shown as an example to which the manufacturing method of the electrostatic actuator according to the present invention is applied. However, the manufacturing method of the electrostatic actuator shown in the first embodiment of the present invention is as follows. The present invention can also be applied to other device manufacturing methods. In particular,
The present invention can be applied to a method for manufacturing a MEMS device such as a wavelength tunable filter or a micropump.
The manufacturing method of the electrostatic actuator, the manufacturing method of the droplet discharge head, and the manufacturing method of the device according to the present invention are not limited to the embodiments of the present invention, and are changed within the scope of the idea of the present invention. can do.

FIG. 2 is an exploded perspective view showing an outline of a configuration of a droplet discharge head manufactured by the method for manufacturing a droplet discharge head according to Embodiment 1 of the present invention. Sectional drawing which shows the outline of a structure of the droplet discharge head. Sectional drawing which shows the outline of the junction state of the equipotential point of the droplet discharge head. The top view which shows the outline of the glass substrate of the droplet discharge head. Sectional drawing which shows the process of the manufacturing method of the droplet discharge head. Sectional drawing which shows the process of the manufacturing method of the droplet discharge head. The perspective view which shows the state which accumulated the glass substrate and the cavity board | substrate using the orientation flat in the process of the manufacturing method of the droplet discharge head. The top view which shows the state which accumulated the glass substrate and the cavity board | substrate using the orientation flat in the process of the manufacturing method of the droplet discharge head. Explanatory drawing which shows the concrete various shapes of the alignment mark of a glass substrate and a cavity board | substrate at the process of the manufacturing method of the droplet discharge head. FIG. 3 is a perspective view showing an example of a droplet discharge device manufactured by the method for manufacturing a droplet discharge head according to the first embodiment. The principal part perspective view which showed an example of the device carrying the electrostatic actuator which concerns on this invention.

Explanation of symbols

1 glass substrate, 2 cavity substrate, 3 nozzle substrate, 4 diaphragm, 5 discharge chamber,
6 Orifice, 7 Reservoir, 8 Electrode, 9 Recess, 10 Droplet discharge head, 11 Terminal, 12 Ink supply hole, 13 Nozzle, 14 Diaphragm, 15 Insulating film, 17a
-17b alignment mark, 18 vibration chamber, 19a-19b orientation flat, 20 electrostatic actuator.

Claims (7)

In the method of manufacturing an electrostatic actuator, comprising an electrode and a diaphragm facing the electrode with a gap, and deforming the diaphragm by applying a voltage between the diaphragm and the electrode,
Comprising a reference line for alignment, and a silicon substrate on which the diaphragm is to be formed;
A reference line for performing alignment, the electrode is formed, and a glass substrate having an outer diameter larger than the outer diameter of the silicon substrate,
A manufacturing method of an electrostatic actuator, wherein the reference lines are overlapped so that the reference lines are substantially in the same direction, and are aligned and bonded so that the outer periphery of the silicon substrate is inside the outer periphery of the glass substrate. The method for manufacturing an electrostatic actuator according to claim 1, wherein the glass substrate and the silicon substrate are bonded by anodic bonding. 3. The method of manufacturing an electrostatic actuator according to claim 1, wherein a reference line provided on the glass substrate and the silicon substrate is an orientation flat or an elongated groove. The static alignment according to any one of claims 1 to 3, wherein the alignment between the glass substrate and the silicon substrate is performed by an alignment mark provided on the glass substrate and an alignment mark provided on the silicon substrate. Manufacturing method of electric actuator. The alignment mark provided on the glass substrate is the alignment mark provided on the glass substrate when both substrates are overlapped so that the outer periphery of the silicon substrate is inside the outer periphery of the glass substrate. 5. The method for manufacturing an electrostatic actuator according to claim 1, wherein the electrostatic actuator is positioned so as to be located inside the outer periphery of the electrostatic actuator. A nozzle substrate having a plurality of nozzles is bonded to the silicon substrate of the electrostatic actuator manufactured by the method for manufacturing an electrostatic actuator according to any one of claims 1 to 5, and the gap between the nozzle substrate and the silicon substrate is bonded. Forming a discharge chamber communicating with each of the nozzles, and manufacturing a droplet discharge head for discharging droplets from the nozzle by deformation of the vibration plate. A device manufacturing method comprising the method of manufacturing an electrostatic actuator according to claim 1.

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