JP3381729B2 - Method of manufacturing inkjet head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, which is a main part of an ink jet recording apparatus for ejecting ink droplets and adhering the ink droplets onto a recording paper surface only when recording is required. The present invention relates to a method of using the same and a method of manufacturing an inkjet head that effectively achieves the object of the present invention.

[0002]

2. Description of the Related Art An ink jet recording apparatus has many advantages such as extremely low noise during recording, high speed printing, and use of plain paper which has a high degree of freedom of ink and is inexpensive. Among these, the so-called ink-on-demand method, which ejects ink droplets only when recording is necessary, is becoming mainstream because it does not require recovery of ink droplets unnecessary for recording.

In this ink-on-demand type ink jet head, as shown in Japanese Patent Publication No. 2-51734, the driving means is a piezoelectric element, and as shown in Japanese Patent Publication No. 61-59911. In addition, there is a method of ejecting the ink with a pressure generated by heating the ink to generate bubbles.

However, the above-mentioned conventional ink jet head has the following problems.

In the former method using a piezoelectric element,
The process of attaching the piezoelectric element chip to each vibration plate for generating pressure in the pressure chamber is complicated, and high speed and high print quality have been particularly required for printing by the recent inkjet recording apparatus. In achieving multi-nozzle and high-density nozzles to achieve the above, it is extremely complicated and takes a lot of time to finely process the piezoelectric element and bond it to each diaphragm. Further, in order to increase the density, it has become necessary to process the piezoelectric element with a width of several tens to several tens of microns, but the dimensional and shape accuracy in the conventional mechanical processing causes a large variation in printing quality. There was a problem.

In the latter method of heating ink, the driving means is formed of a thin-film resistance heating element, so that the above-mentioned problem does not exist, but rapid heating / cooling of the driving means and repeated There is a problem that the life of the inkjet head is short because the resistance heating element is damaged by the impact when the bubbles disappear.

As a solution to these problems, the present applicant has applied for an ink jet head recording apparatus using electrostatic force as a driving means (Japanese Patent Application No. 3-2).
34537), this method has the advantages of small size, high density, high print quality, and long life.

[0008]

However, in order to further enhance these advantages, the following problems remain.

One of them is a problem regarding a gap between a diaphragm which constitutes the ink ejection chamber and an electrode for driving the diaphragm. In the method that uses electrostatic force, the discharge pressure that can be generated with the same voltage is extremely lower than that of the piezoelectric element, and since the generated pressure is proportional to the square of the reciprocal of the distance, it is necessary to suppress variations in print quality. It is necessary to keep the size of this gap within a predetermined range with extremely high accuracy.

The second problem is the dimensional accuracy of the diaphragm, in addition to the above dimensional accuracy of the gap. The ejection pressure is proportional to the cube of the thickness of the diaphragm, and is proportional to the reciprocal of the short side length to the fifth power of the rectangular diaphragm. Therefore, variations in the dimensions of the diaphragm have a very serious influence on the ink ejection characteristics. .

A third problem is a manufacturing method for realizing the dimensional accuracy of the gap and the dimensional accuracy of the diaphragm, which are extremely highly accurate as described above. The anodic bonding method is used for bonding the substrates of this kind. For anodic bonding, a borosilicate glass substrate is connected to the cathode side, and a silicon substrate provided with a nozzle, a vibration plate, etc. is connected to the anode side, and a voltage of 500 V is applied at 300 degrees Celsius for bonding. At a temperature of 300 ° C., Na ions contained in the borosilicate glass move to the cathode side by the electric field, so that an extremely strong electrostatic attractive force is generated at the interface between the silicon and the borosilicate glass, and they adhere to each other.

However, in the gap between the electrode and the diaphragm, a large current may momentarily flow due to dielectric breakdown of the gas or field emission, and the electrode may melt or adhere to the diaphragm to cause a short circuit. . In addition, since the bonding is performed at a significantly higher voltage during anodic bonding than when the inkjet head is driven, the vibrating plate is deformed by the electric field at the time of anodic bonding and is fixed around the vibrating plate. The natural frequency fluctuates. As a result, there is a problem in that the ink ejection characteristics change, or the insulating film on the electrode is pulled toward the diaphragm by the electrostatic attraction and separated from the electrode.

Therefore, an object of the present invention is to first drive an electrode and a vibration in order to be able to drive with an even lower driving voltage in an ink jet head of a system utilizing electrostatic force and to obtain stable high printing quality. It is an object of the present invention to provide a manufacturing method that regulates the gap size between plates and realizes the gap holding means with high accuracy.

Another object of the present invention is to provide an ink jet head having a very high dimensional accuracy of the gap portion and the vibration plate, and hence realizing a small size and a high density, and a method of manufacturing the same.

[0015]

According to the present invention, there are provided a nozzle hole for ejecting an ink droplet, an ejection chamber communicating with each of the nozzle holes, and a vibration plate constituting at least one wall of the ejection chamber. Manufacture of an inkjet head having a formed first substrate and a second substrate provided with a driving unit that causes deformation of the diaphragm, and the driving unit including an electrode formed with the electrode that deforms the diaphragm by electrostatic force. In the method
The method is characterized by including a step of changing the potentials of the vibration plate and the electrode when anodic bonding the first substrate and the second substrate.

Further, the method of manufacturing an ink jet head of the present invention is characterized in that the potential of the electrode is made equal to the potential of the diaphragm.

According to another aspect of the method for manufacturing an ink jet head of the present invention, a nozzle hole for ejecting an ink droplet, an ejection chamber communicating with each of the nozzle holes, and at least one wall of the ejection chamber are formed. A first substrate having a vibrating plate formed thereon and a driving unit that causes the vibrating plate to deform, and a second substrate having an electrode that causes the driving unit to deform the vibrating plate by electrostatic force. In the method of manufacturing an inkjet head having the method, the step of forming a common electrode connected to each of the electrodes on the second substrate, and the step of forming the common plate on the second substrate by anodic bonding The method is characterized by including a step of changing a potential with an electrode and a step of separating the common electrode from the electrode after anodic bonding.

According to another aspect of the method of manufacturing an ink jet head of the present invention, an atmosphere is provided through a passage between the diaphragm formed on the first substrate and the electrode formed on the second substrate. Is characterized by having a gap portion communicating with, and after anodic bonding, the outlet of the passage is sealed by a sealing member.

[0019]

[0020]

[0021]

[0022]

[0023]

The operation of the ink jet head manufacturing method of the present invention is as follows.
When the first substrate with the diaphragm and the second substrate with the electrode are anodically bonded, if the potential difference between the diaphragm and the electrode is adjusted to be reduced, for example, the diaphragm and the electrode are placed at the same potential. When adjusted to, it is possible to prevent discharge and field emission that occur between the diaphragm and the electrode during anodic bonding, and also to prevent peeling of the insulating film due to electrostatic attraction. Therefore, inconveniences such as melting of the electrodes and generation of residual stress in the diaphragm do not occur. Further, by providing a passage to the outside in the gap portion between the diaphragm and the electrode, the pressure rise in the gap portion due to the heating at the time of anodic bonding is eliminated, and the gap length can be maintained as desired, and the diaphragm Generation of residual stress and contact between the diaphragm and the electrode can be prevented. Further, the outlet of the passage is sealed with a sealing member when the entire inkjet head is cooled to room temperature after anodic bonding, so that dust can be prevented from entering the gap portion.

[0024]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is an exploded perspective view of an ink jet head according to a first embodiment of the present invention, which is a partial sectional view. This embodiment shows an example of an edge inkjet type in which ink droplets are ejected from nozzle holes provided at the end of the substrate. 2 is a cross-sectional side view of the assembled whole device, and FIG. 3 is a view taken along the line AA of FIG.

The ink jet head 10 of this embodiment is
It has a laminated structure in which three substrates 1, 2, 3 having a structure described in detail below are stacked and joined.

The intermediate first substrate 1 is a silicon substrate, and a plurality of nozzle grooves 11 are formed on the surface of the substrate 1 so as to form a plurality of nozzle holes 4 and are formed at equal intervals in parallel from one end.
And a recess 12 communicating with each nozzle groove 11 and forming a discharge chamber 6 having a bottom wall as a vibration plate 5, and an ink inlet port forming an orifice 7 provided at the rear of the recess 12. And a concave portion 14 that will form a common ink cavity 8 for supplying ink to each ejection chamber 6. Further, in the lower part of the vibration plate 5, there is provided a concave portion 15 which constitutes the vibration chamber 9 for mounting electrodes described later.

In the present embodiment, the gap between the diaphragm 5 and the electrode arranged opposite thereto, that is, the length G of the gap portion 16 (see FIG. 2, hereinafter referred to as "gap length"). The gap holding means is formed by the recess 15 for the vibration chamber formed on the lower surface of the first substrate 1 so that the difference becomes the difference between the depth of the recess 15 and the thickness of the electrode. here,
The depth of the recess 15 is set to 0.6 μm by etching. The pitch of the nozzle grooves 11 is 0.72 mm,
Its width is 70 μm.

Borosilicate glass is used for the lower second substrate 2 bonded to the lower surface of the first substrate 1.
The vibrating chamber 9 is formed by the joining of the above, and 0.1 μm of gold is sputtered on the substrate 2 at each position corresponding to the vibrating plate 5 in a shape similar to that of the vibrating plate 5, so that the vibrating plate 5 has substantially the same shape as the vibrating plate 5. The electrode 21 is formed by forming a pattern.
The electrode 21 has a lead portion 22 and a terminal portion 23. Further, the glass sputtered film is 0.2
An insulating layer 24 is formed by coating with μm to form a film for preventing dielectric breakdown and short circuit when the inkjet head is driven.

Borosilicate glass is used for the upper third substrate 3 bonded to the upper surface of the first substrate 1, like the second substrate 2. By joining the substrates 3, the nozzle holes 4, the ejection chambers 6, the orifices 7 and the ink cavities 8 are formed.
Is configured. The ink cavity 8 is formed on the substrate 3.
An ink supply port 31 communicating with the above is provided. Ink supply port 3
1 is connected to an ink tank (not shown) via a connection pipe 32 and a tube 33.

Next, the first substrate 1 and the second substrate 2 are anodically joined by applying a voltage of 500 V at a temperature of 300 ° C., and the first substrate 1 and the third substrate 3 are joined under the same conditions, The inkjet head is assembled as shown in FIG. After the anodic bonding, the gap length G between the diaphragm 5 and the electrode 21 on the second substrate 2 is 0.5 μm because it is the difference between the depth of the recess 15 and the thickness of the electrode 21. The gap G1 between the diaphragm 5 and the insulating layer 24 on the electrode 21 is 0.3 μm.

After the ink jet head is assembled as described above, the oscillation circuit 102 is connected between the substrate 1 and the terminal portion 23 of the electrode 21 by the wiring 101 to form an ink jet recording apparatus. The ink 103 is supplied from the ink tank (not shown) to the inside of the substrate 1 through the ink supply port 31, and fills the ink cavity 8, the ejection chamber 6, and the like.

In FIG. 2, 104 is an ink droplet ejected from the nozzle hole 4, and 105 is a recording paper.

The operation of this embodiment configured as described above will be described. The oscillation circuit 102 is applied to the electrode 21 from 0V to 1
When a pulse voltage of 50 V is applied and the surface of the electrode 21 is positively charged, the corresponding lower surface of the diaphragm 5 is negatively charged. Therefore, the diaphragm 5 bends downward due to the electrostatic attraction. Next, when the electrode 21 is turned off,
The diaphragm 5 is restored. Therefore, the pressure in the ejection chamber 6 rapidly rises, and the ink droplets 104 are ejected from the nozzle holes 4 toward the recording paper 105. Then, when the vibration plate 5 is bent again downward, the ink 103 is replenished from the ink cavity 8 into the ejection chamber 6 through the orifice 7.

The ink jet head 10 thus manufactured is incorporated into a printer as shown in FIG.
As a result of ejecting ink droplets at 7 m / sec by driving at 5 kHz, good printing performance was obtained with the above low driving voltage. In FIG. 35, 300 is a platen and 30
1 is an ink tank, 302 is an inkjet head 10.
Carriage, 303 is a pump, 304 is a cap, 3
Reference numeral 05 is a waste ink reservoir, 306 is an ink supply tube, 30
Reference numeral 7 is an ink discharge tube, and 308 is an ejection port discharge tube.

When the gap length between the diaphragm 5 and the electrode 21 was 2.5 μm, the driving voltage was 250 V or more, which was not practical as a printer.

(Embodiment 2) FIG. 4 is an exploded perspective view of an ink jet head according to a second embodiment of the present invention, which is a partial sectional view. This embodiment shows an example of a face inkjet type in which ink droplets are ejected from nozzle holes provided on the surface of the substrate. 5 is a cross-sectional side view of the assembled whole device, and FIG. 6 is a view taken along the line BB of FIG. In the following, parts and members that are the same as or correspond to those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

The ink jet head 10 of this embodiment is
Ink droplets are ejected from nozzle holes 4 formed in the surface of the third substrate 3.

The first substrate 1 in this embodiment has a thickness of 3
It is a silicon substrate having a crystal plane orientation (110) of 80 μm, and the bottom wall of the concave portion 12 forming the discharge chamber 6 is the diaphragm 5 having a thickness of 3 μm. Further, the lower portion of the vibrating plate 5 is not formed with the concave portion for the vibrating chamber as in the first embodiment, and the lower surface of the vibrating plate 5 is a smooth surface by mirror polishing.

The second substrate 2 bonded to the lower surface of the first substrate 1 uses borosilicate glass as in the first embodiment,
A concave portion 25 for mounting the electrode 21 on the substrate 2 is formed by.
The gap length G as described above is formed by etching 5 μm. This recess 25 has the electrode 2 inside.
1, so that the lead portion 22 and the terminal portion 23 can be mounted, a pattern is formed in a slightly larger shape similar to the shape of the electrode portion. The electrode 21 is produced by sputtering ITO in the recess 25 to a thickness of 0.1 μm to form an ITO pattern, and only the terminal portion 23 is sputtered with gold for bonding. Further, except for the electrode terminal portion 23, the entire surface is covered with a glass sputtered film to a thickness of 0.1 μm to form an insulating layer 24.
Although the insulating layer 24 is drawn flat in FIG. 4, the upper part of the recess 25 is actually recessed.

Therefore, the gap length G in this embodiment is 0.4 μm after the anodic bonding, and the gap G1 is 0.3 μm.
Has become.

Further, a SUS plate having a thickness of 100 μm is used as the third substrate 3 bonded to the upper surface of the first substrate 1, and the surface portion of the substrate 3 is communicated with the recess 12 for the discharge chamber. Each nozzle hole 4 is provided, and an ink supply port 31 is provided so as to communicate with the recess 14 for the ink cavity.

When a pulse voltage of 0V to 100V was applied to the electrode 21 by the oscillation circuit 102 using this ink jet head 10, good printing performance was obtained as in the first embodiment. The gap length G is 2.3μ.
In the case of m, the driving voltage was 250 V or more, which was not practical as a printer.

(Embodiment 3) FIG. 7 is an exploded perspective view of an ink jet head according to a third embodiment of the present invention, which is a partial sectional view. FIG. 8 is an enlarged perspective view showing a part of the inkjet head.

In this embodiment, the gap length holding means is the first
Of the SiO ₂ films 41 and 42 formed in advance at the joint between the substrate 1 and the second substrate 2. That is, these SiO ₂ films 41 and 42 function as gap spacers. As the first substrate 1, a single crystal silicon wafer having a crystal plane orientation of (100) is used, and a SiO ₂ film 41 is formed on the lower surface thereof except for a portion corresponding to the diaphragm 5.
To have a thickness of 0.3 μm, for example. Similarly, the second substrate 2 is also a single crystal silicon wafer having a crystal plane orientation (100), and the SiO ₂ film 42 is formed on the upper surface of the _second substrate ₂ except for the electrodes 21 to have a thickness of 0.2 μm, for example. Therefore, the gap length G (see FIG. 8) when the two substrates 1 and 2 are joined is 0.5 μm.

FIG. 9 shows the manufacturing process of the first substrate in this embodiment.

First, both sides of a (100) plane-oriented silicon wafer are mirror-polished to form a silicon substrate 5 having a thickness of 200 μm.
1 (FIG. 9A), the silicon substrate 51 was subjected to thermal oxidation treatment at 1100 ° C. for 4 hours in an atmosphere of oxygen and water vapor, and both surfaces of the silicon substrate 51 were made of SiO 2 having a thickness of 1 μm.
_Two films 41a and 41b are formed (FIG. 9B). Si
The O ₂ films 41a and 41b are used as an etching resistant material.

Then, on the SiO ₂ film 41a on the upper surface,
A photoresist pattern (not shown) corresponding to the shapes of the nozzle 4, the ejection chamber 6, the orifice 7, and the ink cavity 8 is formed, and the exposed portion of the SiO ₂ film 41a is removed by etching with a hydrofluoric acid-based etching solution. The photoresist pattern is removed (FIG. 9C).

Next, a silicon substrate 51 made of an alkaline solution.
Anisotropic etching is performed. As is well known, when single crystal silicon is etched with an aqueous solution of potassium hydroxide or an alkali such as hydrazine, anisotropic etching is possible because the difference in etching rate between crystal planes is large. Specifically, since the etching rate of the (111) crystal plane is the smallest, as the etching progresses, (11
1) A structure in which the surface remains as a smooth surface is obtained.

In this example, etching was performed using an aqueous potassium hydroxide solution containing isopropyl alcohol. Since the mechanical deformation characteristics of the diaphragm are determined by the dimensions of each portion of the diaphragm, the design dimensions of each portion of the diaphragm are determined from the ink ejection characteristics required for the inkjet head. In this embodiment, the width h of the diaphragm 5 is 500 μm.
m and the thickness t are 30 μm (see FIG. 10).

In the (100) plane-oriented silicon substrate 51, the (111) plane intersects with the (100) plane, which is the substrate surface, at an angle of about 55 ° in terms of the crystal structure. ) When the dimensions of each portion to be formed in the plane-oriented silicon substrate are determined, the mask pattern dimension of the etching resistant material is uniquely determined with respect to the thickness of the first substrate. As shown in FIG. 10, when the width d at the upper end of the discharge chamber 6 is set to 740 μm and 170 μm is etched, the diaphragm 5 having a width h of 500 μm and a thickness t of 30 μm is obtained. In the actual etching, the (111) plane is etched (undercut) little by little.
The dimension d at is slightly larger than the mask pattern width d1. Therefore, the mask pattern width d1 is (11
1) Since the undercut dimension of the surface 12a must be reduced, the thickness is 730 μm in this embodiment, and a predetermined amount (170 μm) of etching was performed with the above alkaline etching solution (FIG. 9D).

Next, SiO _{2 on} the lower surface of the silicon substrate 51 is
The pattern processing of the film 41b is performed. Although the thickness of the SiO ₂ film 41b was 1 μm as described above at the stage of FIG. 9B, the SiO ₂ film 41b was not alkalinized in the alkaline anisotropic etching step of FIG. 9D. It is etched by the liquid and its thickness is reduced to 0.3 μm. In this embodiment, since the etching rate of the SiO ₂ film is very small, the decrease in the thickness of the SiO ₂ film 41b is reproducible and uniform.

Next, the SiO ₂ film 41b (41) (not shown) photoresist pattern corresponding to the shape to the diaphragm 5 onto the forming, SiO ₂ by a hydrofluoric acid etching solution
The exposed portion of the film 41b is removed by etching to remove the photoresist pattern. At the same time, the SiO ₂ film 41a remaining on the front surface of the substrate 51 is completely removed (FIG. 9E).

Through the steps described above, the first substrate 1 shown in FIG. 7 is formed.

Next, FIG. 11 shows a manufacturing process of the second substrate in this embodiment.

First, both sides of the (100) plane oriented n-type silicon substrate 52 are mirror-polished, and the silicon substrate 52 is subjected to thermal oxidation treatment at 1100 ° C. for a predetermined time in an atmosphere of oxygen and water vapor, and then the silicon substrate 52. SiO ₂ film 42 on both sides of
a and 42b are formed (FIG. 11A).

Next, a photoresist pattern (not shown) corresponding to the shape of the electrode 21 is formed on the SiO ₂ film 42a on the upper surface, and the SiO ₂ film 4 is formed with a hydrofluoric acid-based etching solution.
The exposed portion of 2a is removed by etching to remove the photoresist pattern (FIG. 11B).

Next, the exposed Si portion 43 of the silicon substrate 52 is doped with B (boron). The processing method is as follows. The silicon substrate 52 is fixed in a quartz tube by a quartz holder, and vapor generated by bubbling BBr ₃ with N ₂ as a carrier is introduced into the quartz tube together with O ₂ . 11
After processing at 00 ° C. for a predetermined time, the silicon substrate 52
Was subjected to light etching with a hydrofluoric acid-based etching solution, and then drive-in was performed in O ₂ to form the exposed Si portion 43 as a p-type layer 44 (FIG. 11C). The p-type layer 4
4 functions as the electrode 21 in FIG.

In the step of FIG. 11C, since the SiO ₂ films 42a and 42b on the surface of the silicon substrate 52 are increased in thickness, the thickness of the SiO ₂ film 42a after the thickness is increased in this embodiment. The thickness is 0.2 μm. Then, next, a photoresist pattern (not shown) corresponding to the shape of the p-type layer 44 (electrode 21) is formed, and the exposed portion of the SiO ₂ film 42a is removed by etching with a hydrofluoric acid-based etching solution (FIG. 11). (D)), the second substrate 2 shown in FIG.
Is formed.

In the ink jet head of this embodiment, the size of the gap length G between the vibrating plate 5 and the electrode 21 is 0.5 μm in view of the ink ejection characteristics of the ink jet head.
Since the thickness of the SiO ₂ film 41b of the first substrate 1 is 0.3 μm as described above,
In the step (c), the thickness of the SiO ₂ film 42a is 0.2.
The process is performed so that the thickness becomes μm.

Substrates 1 and 2 formed by the above steps
Are bonded by the Si-Si direct bonding method to form the head structure enlarged in FIG. The joining process is as follows.

First, the silicon substrate 1 is washed with a mixed solution of sulfuric acid and hydrogen peroxide solution (100 ° C.), dried, and then the corresponding patterns of the substrates 1 and 2 are aligned with each other. Overlap. When both substrates 1 and 2 are heat-treated at 1100 ° C. for 1 hour in this state, a strong bonded state is obtained.

1 manufactured by a series of steps of this embodiment
The gap length G of the 00 inkjet heads is 0.50 ± 0.05 μm, and the thickness of the diaphragm is 30.0.
It was distributed in the range of ± 0.8 μm. When these inkjet heads were driven at 100 V and 5 kHz, the ejection speed of ink droplets was 8 ± 0.5 m / s, and the ink droplet volume was in the range of (0.1 ± 0.01) × 10 ⁻⁶ cc. It was distributed, and good printing was obtained in the actual printing test.

In the present embodiment, the electrode 21 was formed by forming the p-type layer by the vapor phase process using BBr ₃ , but the p-type layer forming method is not limited to this method, for example, an ion implantation method or B ₂ The p-type layer can be similarly formed by a method such as spin coating with a coating agent in which O ₃ is dispersed in an organic solvent or a method using a BN (boron nitride) plate as a diffusion source. In order to form the p-type layer, other materials such as Al and Ga are used.
Group III elements can also be used. It is also possible to use the silicon substrate 2 as a p-type substrate and the electrode 21 as an n-type layer. In this case as well, the V group element such as P, As, Sb is doped by various doping methods as described above. Then electrode 21
Can be

Further, in this embodiment, the SiO ₂ film 4 is used.
The gap portion was formed by 1 and 42.
Since the principle of direct bonding method, bonding even without either of the SiO ₂ film 41 and 42 are possible, SiO ₂ film 4
Either 1 or 42 has the same thickness as the desired gap length, the other SiO ₂ film is removed by a hydrofluoric acid-based etching solution in the process, and a Si-Si direct bonding step is performed to obtain the same quality. A gap part can be formed.

Further, in the present embodiment, the SiO ₂ film as the gap spacer was used as an etching mask in the alkali anisotropic etching of Si, and although a slight film loss occurred, it was slightly decreased during the etching. The surface roughness tends to deteriorate. In this case, it is possible to remove the entire SiO ₂ film with a hydrofluoric acid-based etching solution and then form a SiO ₂ film having a desired film thickness by thermal oxidation to form a gap spacer.

In this embodiment, the gap length is set to 0.5 μm because of the specifications of the ink jet head.
Since the Si thermal oxide film can be easily and accurately formed up to the thickness of 1.5 μm, when the specification value of the gap length is 0.05 to 2.0 μm, the gap spacer S is used.
By just adjusting the thickness of the i thermal oxide film according to the specifications, an ink jet head with high dimensional accuracy of the gap portion can be obtained as in the case of the present embodiment.

(Embodiment 4) FIG. 12 is a perspective view showing a partial cross section of a first substrate for an ink jet head according to a fourth embodiment of the present invention. In the inkjet head of the present embodiment, the structures of the second substrate and the third substrate on which the electrodes are formed are the same as those of the third embodiment, and therefore the description and illustration are omitted.

In the present embodiment, the second electrode 46 made of a p-type or n-type impurity layer is formed on the gap facing surface 45 of the diaphragm 5 in FIG. 12, and the frequency characteristic when the ink jet head is driven by the oscillation circuit or It improves crosstalk. However, the gap length G in the present embodiment is a gap distance between the second electrode 46 and the electrode 21 (see FIG. 7) on the second substrate. The space holding means is formed on the lower surface of the first substrate 1 by the method described later.
It is composed of the iO ₂ film 41 and the SiO ₂ film 42 formed on the upper surface of the second substrate described in the third embodiment. Even in this case, the gap length G can be secured only by at least one of the SiO ₂ films.

The manufacturing process of the first substrate in this embodiment is shown in FIG.

First, both surfaces of an n-type (100) plane-oriented silicon wafer are mirror-polished to prepare a silicon substrate 53 having a thickness of 200 μm (FIG. 13A).
3 was subjected to thermal oxidation treatment at 1100 ° C. for 4 hours in an atmosphere of oxygen and water vapor, and a thickness of 1 μm was applied to both surfaces of the silicon substrate 53
SiO ₂ films 41a and 41b are formed (see FIG. 13).
(B)).

Then, on the SiO ₂ film 41b on the lower surface,
A photoresist pattern (not shown) corresponding to the shapes of the electrode 46 and the lead portion (not shown) of FIG. 12 is formed,
The exposed portion of the SiO ₂ film 41b is removed by etching with a hydrofluoric acid-based etching solution to remove the photoresist pattern (FIG. 13C).

Next, the exposed Si portion 47 of the silicon substrate 53 is doped. The processing method is the same as that of the third embodiment, and the p-type layer 48 is formed. The p-type layer 48 functions as the second electrode 46 (FIG. 13).
(D)).

Next, on the SiO ₂ film 41a of the upper surface, the nozzle hole 4, forming a photoresist pattern corresponding to the shape of such a discharge chamber 6 (not shown), SiO ₂ in a hydrofluoric acid etching solution The exposed portion of the film 41a is removed by etching,
The photoresist pattern is removed (FIG. 13)
(E)).

The subsequent steps are performed in the same manner as in the case of the third embodiment, and the vibrating plate 5, the nozzle 4, the discharge chamber 6, the orifice 7, the formation of the ink cavity 8 and the gap between the vibrating plate 5 and the second substrate are formed. Patterning of the SiO ₂ film 41b for forming is performed (FIGS. 13E to 13G).

Also in this embodiment, as in the third embodiment,
Various methods can be used to form the electrode 46, and various dopants can be used.

In the present embodiment, since the drive electrodes 46 are formed on the individual diaphragms 5, it is possible to speed up the drive by the oscillation circuit, that is, speed up the printing speed.

In the third embodiment, the driving frequency at which ink droplets are individually formed into a spherical shape is 5 k at maximum.
However, in this embodiment, the drive frequency is 7 Hz.
improved to kHz. In addition, in the present embodiment, the lead portion for connecting each electrode 46 and the oscillation circuit also has the electrode 4.
It is formed at the same time as 6 and the size and speed of the inkjet head are reduced.

(Fifth Embodiment) FIG. 14 is an exploded perspective view of a partial cross section of an ink jet head according to a fifth embodiment of the present invention. The ink jet head of this embodiment has basically the same structure as that of the third embodiment shown in FIG. 7, but a diaphragm formed when the first substrate 1 and the second substrate 2 are joined together. The borosilicate glass thin film 49 is a thin film for defining the gap between the electrode 5 and the electrode 21, and is formed on the lower surface of the first substrate 1.

FIG. 15 shows the manufacturing process of the first substrate in this embodiment.

First, both sides of a (100) plane-oriented silicon wafer are mirror-polished to form a silicon substrate 5 having a thickness of 200 μm.
4 (FIG. 15 (a)), the silicon substrate 54 was subjected to thermal oxidation treatment at 1100 ° C. for 4 hours in an atmosphere of oxygen and water vapor, and both sides of the silicon substrate 54 were made of Si having a thickness of 1 μm.
O ₂ films 41a and 41b are formed (FIG. 15B).

Then, on the SiO ₂ film 41a on the upper surface,
A photoresist pattern (not shown) corresponding to the shape of the nozzle hole 4, the discharge chamber 6 and the like is formed, the exposed portion of the SiO ₂ film 41a is removed by etching with a hydrofluoric acid-based etching solution, and the photoresist pattern is removed. Yes (Fig. 15
(C)).

Next, anisotropic etching of silicon is performed with an alkaline solution. Example 3 is the anisotropic etching condition.
After forming the nozzle hole 4, the discharge chamber 6 and the like in the same manner as in the above case, the SiO ₂ films 41a and 4
1b is removed with a hydrofluoric acid-based etching solution (FIG. 15).
(D)).

Next, the diaphragm 5 and the electrode 21 in FIG.
And a borosilicate glass thin film 49 which functions as a gap spacer for accurately defining the distance between the thin film and the borosilicate glass thin film 49 and serves as a bonding layer in bonding by the anodic bonding method.
It is formed on the lower surface of the silicon substrate 54.

First, the vibration plate 5 is formed on the lower surface of the silicon substrate 54.
A photoresist pattern 50 corresponding to the shape of FIG. 15 (FIG. 15E) is formed, and then a borosilicate glass thin film 49 is formed on the lower surface of the silicon substrate 54 by a sputtering device (FIG. 15F). When the silicon substrate 54 is immersed in an organic solvent and ultrasonic vibration is applied to remove the photoresist pattern 50, as shown in FIG. 15G, a portion as a gap spacer is formed on a portion other than the portion corresponding to the diaphragm 5. A silicate glass thin film 49 is formed. The sputtering conditions for the borosilicate glass thin film 49 are as follows. As a sputter target, Corning's # 7
740 glass, sputter atmosphere 80% Ar-2
RF power 6 W / cm ² with 0% O ₂ and pressure 5 mTorr
Was applied to form a glass thin film 49 having a thickness of 0.5 μm.

As the second substrate 3 and the third substrate 3 shown in FIG. 14, those manufactured by the method described in Example 3 are used to assemble an ink jet head. First, the first
The anodic bonding between the substrate 1 and the third substrate 3 is performed by the method described in Example 3 to bond and integrate the substrate 1 and the substrate 3. Next, the first substrate 1 and the second substrate 2 are bonded by the anodic bonding method. The diaphragm 5 formed on the substrate 1 and the substrate 2
After aligning and aligning with the electrode 21 formed on the substrate 1, the substrate 1 and the substrate 2 are placed on a hot plate at 300 ° C.
Then, the substrate 1 side was positive and the substrate 2 side was negative, and a DC voltage of 50 V was applied for 10 minutes to perform anodic bonding.

When an actual printing test was conducted on the ink jet head manufactured in this example, good printing was obtained as in the case of Example 3.

In this embodiment, the diaphragm 5 and the electrode 21 are
Borosilicate glass thin film 4 for forming a gap with
Although 9 is formed on the lower surface of the substrate 1, the same effect can be obtained when the borosilicate glass thin film is formed not on the lower surface of the first substrate but on the upper surface of the second substrate due to the principle of anodic bonding. .
The method for forming the borosilicate glass thin film is the same as that in the present embodiment, and in anodic bonding between the first substrate and the second substrate, the first substrate side is positive and the second substrate is 300 ° C. Anodic bonding is possible by applying a DC voltage of 50 V with the substrate side of No. 2 being negative, and the quality of the inkjet head obtained here is exactly the same as that of this embodiment.

In this embodiment, since the first substrate and the second substrate can be bonded at 300 ° C., the following effects are produced. The electrode formed on the second substrate does not have to be p-type or n-type impurities as described in Example 3, but has a melting point of, for example, Au or Al of 100 degrees Celsius. Since the metal film can be used, that is, the electric resistance value of the electrode can be reduced, the driving frequency of the inkjet head can be improved.

(Embodiment 6) FIG. 16 is a perspective view showing a partial cross section of a first substrate for an ink jet head according to a sixth embodiment of the present invention. In the inkjet head of this embodiment, the second substrate and the third substrate on which electrodes are formed have the same structure as that of the third embodiment.

The first substrate 1 of the present embodiment is obtained by processing a silicon substrate 57 in which an n-type Si layer 56 is epitaxially grown on the lower surface of a p-type silicon substrate 55, and electrochemical alkaline anisotropic etching ( (Details will be explained later)
By this, a part of the p-type silicon substrate 55 is selectively removed by etching to obtain the diaphragm 5 with high thickness accuracy.

FIG. 17 shows the manufacturing process of the first substrate in this embodiment.

First, both sides of a p-type (100) plane-oriented silicon wafer are mirror-polished to form a silicon substrate 55 having a thickness of 170 μm, and an n-type Si layer 56 having a thickness of 30 μm is formed on the lower surface of the silicon substrate 55. The silicon substrate 57 is obtained by epitaxial growth to a thickness (FIG. 17A).
For example, the silicon substrate 55 is a substrate doped with B (boron), and its concentration is 4 × 10 ¹⁵ cm ⁻³ . The n-type Si layer 56 is Al-doped and has a concentration of 5 × 10 ¹⁵ cm ⁻³ . In the above epitaxial growth step, the Si layer 56 having a uniform thickness can be formed, and the error of ± 0.2 μm can be controlled with respect to the target thickness of 30 μm.

Next, the silicon substrate 57 is subjected to thermal oxidation treatment at 1100 ° C. for 4 hours in an atmosphere of oxygen and water vapor, and the SiO ₂ film 41a having a thickness of 1 μm is formed on both surfaces of the silicon substrate 57.
And 41b are formed (FIG. 17B).

Then, on the SiO ₂ film 41a on the upper surface,
A photoresist pattern (not shown) corresponding to the shape of the nozzle hole 4, the discharge chamber 6, etc. is formed, and the SiO ₂ film 4 on the lower surface is formed.
1b, a photoresist pattern (not shown) corresponding to the electrically conductive opening 58 is formed, and the exposed portions of the SiO ₂ films 41a and 41b are removed by etching with a hydrofluoric acid-based etching solution. The pattern is removed (FIG. 17 (c)).

Next, the above-mentioned electrochemical anisotropic etching is performed by the method shown in FIG. In FIG.
While the n-type Si layer 56 is positive and the platinum plate 80 is negative and a direct current voltage of 0.6 V is applied, the silicon substrate 57 is immersed in a KOH aqueous solution (70 ° C.) containing isopropyl alcohol for etching. When the exposed portion (the portion not covered with the SiO ₂ film 41a) of the p-type silicon substrate 55 is completely removed by etching, the n-type Si layer 56 is inactivated by the positive DC voltage, so that the etching proceeds. No, the etching is completed at this point, and FIG.
A silicon substrate in the state of is obtained.

Then, on the SiO ₂ film 41b on the lower surface,
A photoresist pattern (not shown) having a shape corresponding to the vibrating plate 5 is formed, and SiO _{2 is} etched with a hydrofluoric acid-based etching solution.
The exposed portion of the film 41b is removed by etching to remove the photoresist pattern. At the same time, if all the SiO ₂ film 41a remaining on the surface of the p-type silicon substrate 55 is removed, the first substrate 1 shown in FIG. 16 is formed (FIG. 17 (e)).

The steps other than the above are the same as in the case of the third embodiment. The thickness of the vibration plate of 100 ink jet heads manufactured by the series of steps of this embodiment is 3
It is distributed in the range of 0.0 ± 0.2 μm, and the film thickness accuracy of the n-type Si layer 56 by the above epitaxial process is maintained almost as it is. When these inkjet heads were driven at 100 V and 5 kHz, the ejection speed of ink droplets was 8 ± 0.2 m / s, and the ink droplet volume was (0.1 ± 0.005) × 10 ⁻⁶ cc. It was distributed and good printing was obtained in the actual printing test.

(Embodiment 7) FIG. 19 is a perspective view showing a partial cross section of a first substrate for an ink jet head according to a seventh embodiment of the present invention. In the ink jet head of this embodiment, the second substrate and the third substrate on which electrodes are formed have the same structure as in the third embodiment, and the manufacturing process is also the same, so a detailed description thereof will be omitted.

The first substrate 1 of this embodiment is obtained by processing a silicon substrate 63 in which an n-type Si layer 62 is epitaxially grown on the lower surface of a p-type silicon substrate 61, and the crystal plane orientation of the p-type silicon substrate 61 is processed. Is (110). (1
As is well known, a silicon substrate with a (10) plane orientation has
The (1) plane intersects the (110) plane substrate surface perpendicularly in the <211> direction, that is, it is possible to form a wall structure perpendicular to the substrate surface by anisotropic etching using alkali.

In the present embodiment, by utilizing this fact, the pitch interval is narrowed when a large number of ink jet constituent units including nozzles, discharge chambers, etc. are arranged to realize high density of nozzles.

FIG. 20 shows the manufacturing process of the first substrate in this embodiment.

FIGS. 20A to 20D show C- in FIG.
It corresponds to the cross-sectional view taken along the line C, and FIGS.
9 corresponds to a sectional view taken along line DD of FIG.

First, both surfaces of a p-type (110) plane-oriented silicon wafer are mirror-polished to form a silicon substrate 61 having a thickness of 170 μm, and an n-type Si layer 62 having a thickness of 3 μm is formed on the lower surface of the silicon substrate 61. The silicon substrate 63 is obtained by epitaxial growth with a thickness to obtain a silicon substrate 63 (FIG. 20A). For example, the silicon substrate 61 is a substrate doped with B and its concentration is 4 × 10 ¹⁵ cm ⁻³ . In addition, n-type Si
The layer 62 is Al-doped and has a concentration of 5 ×
It is 10 ¹⁴ cm ^-3 . In the above epitaxial growth process, an error of ± 0.05 μm can be controlled with respect to the target thickness of 3 μm.

Next, the silicon substrate 63 is subjected to thermal oxidation treatment at 1100 ° C. for 4 hours in an atmosphere of oxygen and water vapor, and the SiO ₂ film 41a having a thickness of 1 μm is formed on both surfaces of the silicon substrate 63.
And 41b are formed (FIG. 20 (b)).

Then, on the SiO ₂ film 41a on the upper surface,
A photoresist pattern (not shown) corresponding to the shape of a cavity, an ink cavity, etc. is formed, and Si on the lower surface is formed.
A photoresist pattern (not shown) corresponding to the electrical conduction opening 64 is formed on the O ₂ film 41b, and the exposed portions of the SiO ₂ films 41a and 41b are removed by etching with a hydrofluoric acid-based etching solution. The photoresist pattern is removed (FIG. 20 (c)). The size of the photoresist pattern corresponding to the shape of the discharge chamber 6 is 50 μm in width,
The spacing between adjacent patterns was 20.7 μm, that is, the pitch spacing was 70.7 μm, and the ink droplet dot density per inch was 360 dpi (dots per inch).

Next, the above-described electrochemical anisotropic etching is applied to the silicon substrate 63 by the same method as that described in the sixth embodiment, and etching is performed until the p-type silicon substrate 61 penetrates (FIG. 20). (D)). Figure 20 (d)
The recess 6 obtained in the step of (1) is composed of a wall perpendicular to the surface of the silicon substrate 63.

Next, during the electrochemical anisotropic etching, a photoresist pattern (not shown) corresponding to the nozzles 4, orifices 7 and the like is formed on the SiO ₂ film 41a with a slightly reduced thickness, and the SiO ₂ film on the lower surface is formed. _The entire surface of the ₂ film 41b is covered with a photoresist film (not shown), and the exposed portion of the SiO ₂ film 41a is removed by etching with a hydrofluoric acid-based etching solution to remove the photoresist pattern (see FIG. 2).
0 (e)).

Next, similarly to the step of FIG. 20D, etching is performed by electrochemical etching until the nozzle 4 and the orifice 7 having a depth of 30 μm are formed (FIG. 20).
(F)).

Finally, the entire silicon substrate is immersed in a hydrofluoric acid-based etching solution to remove the SiO ₂ films 41a and 41b to obtain the first substrate 1 (FIG. 20 (g)). The width of the discharge chamber formed on the obtained first substrate slightly expanded to 55 μm due to undercutting during etching,
The pitch interval was 70.7 μm, and the first substrate having desired dimensions was obtained. There is an optimum value for the width of the cavity from the ink ejection characteristics, but if the dimension of the photoresist pattern is determined in consideration of the above-mentioned undercut, a cavity having a desired shape can be obtained.

(Embodiment 8) FIG. 21 is a perspective view showing a partial cross section of a first substrate for an ink jet head according to an eighth embodiment of the present invention. The diaphragm 5 in the ink jet head of this embodiment is a high-concentration B (boron) -doped layer 66, and the doped layer 66 has the same thickness as the desired diaphragm thickness. As for the etching rate in Si etching with alkali, when the dopant is B, it is known that the etching rate becomes very small in a high concentration region (about 5 × 10 ¹⁹ cm ⁻³ or more). In the present embodiment, by utilizing this fact, when the vibrating plate forming region is a high concentration B-doped layer and the ejection chamber 6 and the ink cavity 8 are formed by alkali anisotropic etching, the time when the B-doped layer 66 is exposed. With the so-called etch stop technique in which the etching rate becomes extremely small, the diaphragm 5, the discharge chamber 6 and the like are formed in a desired shape.

FIG. 22 shows the manufacturing process of the first substrate in this embodiment.

First, both sides of an n-type (110) plane-oriented Si wafer are mirror-polished to form a 200 μm-thick silicon substrate 65, and the silicon substrate 65 is exposed to oxygen and water vapor atmosphere at 1100 ° C. for 4 hours. Is performed to form SiO ₂ films 41a and 41b having a thickness of 1 μm on both surfaces of the silicon substrate 65 (FIG. 22A).

Then, a photoresist pattern (not shown) corresponding to the shapes of the vibrating plate (B-doped layer) 66, the ink cavity 8, and the lead portion (not shown) of the electrode is formed on the SiO ₂ film 41b on the lower surface. The exposed portion of the SiO ₂ film 41b (the portion corresponding to the vibrating plate, the ink cavity and the lead portion) is removed by etching with a hydrofluoric acid-based etching solution to remove the photoresist pattern (FIG. 22).
(B)).

Next, the exposed Si of the silicon substrate 65
The portion 67 is doped with B. The treatment method is the same as in Example 3 to form the B-doped layer 66, but the concentration of B is 5 × 10 ²⁰ cm ⁻³ , and the thickness of the doped layer is 10.
The treatment is performed under the doping condition such that the thickness becomes μm (FIG.
(C)). In order to achieve the above-mentioned high B concentration and thick dope layer thickness, among the various methods described in Example 3, a spin coating method of a B ₂ O ₃ agent or a BN plate is used rather than the ion implantation method. The diffusion method using is preferable, but any method can be realized.

Then, on the SiO ₂ film 41a on the upper surface,
A photoresist pattern (not shown) corresponding to the shapes of the discharge chamber 6, the ink cavity 8, the etching end point detection pattern 71, etc. is formed, and the exposed portion of the SiO ₂ film 41a is removed by etching with a hydrofluoric acid-based etching solution. , The photoresist pattern is removed (FIG. 22D). The size of the photoresist pattern corresponding to the discharge chamber 6 was the same as in Example 7, with a width of 50 μm and a gap between adjacent patterns of 20.7 μm.

Next, the alkali anisotropic etching of the silicon substrate 65 is performed. An aqueous KOH solution (concentration: 20% by weight, temperature: 80 degrees Celsius) was used as the etching solution.
As described above, the etching rate in alkaline etching of Si has a B concentration dependency as shown in FIG.
In the n-type Si substrate, etching proceeds at an etching rate of about 1.5 μm / min, but in the high-concentration B region, the etching rate is 0.01.
The etching rate is reduced to about μm / min.

Since the thickness (design value) of the diaphragm 5 in this embodiment is 10 μm, the total thickness of the silicon substrate 65 is 200
190 μm of the μm may be removed by etching to form the ejection chamber 6, the ink cavity 8 and the like, but in reality, the silicon substrate 65 has a variation in the plate thickness within the plane (± 1 to 2).
μm), it is difficult to make the diaphragm 5 uniform in thickness.

In this embodiment, the thickness of the diaphragm is accurately formed by the following method. 19 silicon substrate
To etch 0 μm, it takes about 126 minutes 40
Second etching is required. Further, it takes about 6 minutes and 40 seconds to perform etching of 10 μm, and therefore, a total of 13 is required for etching of 200 μm.
It takes 3 minutes and 20 seconds. The silicon substrate in the state of FIG. 22D is etched by the above etching solution for a total of about 133 minutes and 20 seconds. About 126 after starting etching
At the time when 40 minutes have passed, the discharge chamber portion is about 190
Etching of μm progresses, etching surface (not shown)
Has almost reached the interface with the B-doped layer 66, or has reached the interface itself. On the other hand, in the etching end point detecting pattern 71, the etching of about 190 μm is also progressing. In this process, continue (continuously)
Although the etching is performed for about 6 minutes and 40 seconds, if the etching surface does not reach the B-doped layer 66, the etching proceeds similarly at an etching rate of 1.5 μm / min. When reaching the doped layer 66, the etching rate sharply decreases to about 0.01 μm.
/ Min, so B is not possible with an etching time of at most about 6 minutes.
The doped layer 66 is hardly etched and has a thickness of 10 μm.
The diaphragm 5 which is a B-doped layer of m is formed. On the other hand, in the portion of the etching end point detection pattern 71, the etching proceeds similarly at an etching rate of about 1.5 μm / min, and the through hole 72 is formed by a total of about 133 minutes and 20 seconds. As mentioned above, the silicon substrate 6
Although there is some variation in the etching time for forming the through hole 72 due to the variation in the plate thickness of No. 5, various means (for example, work Etching is completed by visual observation of a person, or by irradiating the etching end point detection pattern with laser light from one side and detecting the laser light at the time of forming the through hole by the light receiving element installed on the other side (Fig. 22 (e)).

Next, the SiO ₂ film 41b on the lower surface is formed in the third embodiment.
In the same manner as in the case of, the patterning for defining the interval with the electrode formed on the second substrate is performed, and the first substrate 1
To get

The diaphragm 5 formed by the above steps is
Thickness variation within the surface of the silicon substrate 65 (± 1 to 2
(μm), but could be formed with an accuracy of 10 ± 0.1 μm. This error of ± 0.1 μm is considered to be due to the variation in the B doping depth, not the variation in the alkali etching.

In the method of this embodiment, the accuracy of the thickness of the diaphragm is determined by the accuracy of the thickness of the B-doped layer. 10 μm
The method using BBr ₃ as a diffusion source described in Example 3 is the most preferable in order to obtain accurate thickness accuracy in a moderate thickness region, but other methods may also be used to optimize the processing conditions. _The dope thickness accuracy similar to the method using ₃ can be obtained.

In the present embodiment, at the same time as B-doping the vibrating plate portion, B-doping to the continuous lead portion from the vibrating plate is performed, that is, with the same structure as the vibrating plate described in the fourth embodiment, Since the drive electrodes corresponding to the respective diaphragms are formed by the concentration B-doped portions, the drive frequency can be improved at the same time.

In this embodiment, the n-type substrate is used as the silicon substrate. However, even if the silicon substrate is the p-type substrate, the diaphragm can be formed by B doping at the same time. In Examples 9 to 12 below, the anodic bonding method for substrates according to the present invention will be described in detail.

(Embodiment 9) FIG. 24 is a schematic view showing an embodiment of the anodic bonding method of the present invention, and is a sectional view of a bonding apparatus used for this bonding method and both substrates being bonded. FIG. 25 is a plan view of the joining device.

In this embodiment, the first silicon substrate 1 and the second silicon substrate 1
A method for anodic bonding with the borosilicate glass substrate 2 will be described.

The bonding apparatus 110 in this embodiment is composed of an anode-side bonding electrode plate 111 connected to the positive side of the power source 113.
And a cathode side bonding electrode plate 112 connected to the negative side of the power supply 113, and a terminal plate 115 protruding from the anode side bonding electrode plate 111 via a spring 114. The anode-side bonding electrode plate 111 and the cathode-side bonding electrode plate 112 are plated with gold on the surface of a copper plate for the purpose of reducing the contact resistance on the surface. In addition, the terminal board 115
Is composed of a single contact plate so that the plurality of electrodes 21 on the borosilicate glass substrate 2 and the silicon substrate 1 are equipotential during anodic bonding. This terminal board 115 also has a spring 114.
Is connected to the anode-side bonding electrode plate 111 by means of a spring 114, and an appropriate contact pressure is maintained against the electrode 21 by means of a spring 114. The terminal plate 115 is brought into contact with the terminal portion 23 of the electrode 21.

Silicon substrate 1 and borosilicate glass substrate 2
After cleaning, the vibrating plate 5 and the electrode 21 are aligned with each other using an aligner (not shown) and set as shown in FIGS. 24 and 25. In addition, the electrode 21 and the electrode plates 111 and 112 are placed in a nitrogen gas atmosphere in order to prevent them from being oxidized.

For anodic bonding, first, both substrates 1, 2
Is heated, but in order to prevent the borosilicate glass substrate 2 from cracking due to a rapid temperature rise, the temperature is raised to 300 ° C. over about 20 minutes. Then, a voltage of 500 V is applied by the power source 113 for about 20 minutes to bond the two substrates 1 and 2. At the time of bonding, a current flows due to the movement of Na ions in the borosilicate glass substrate 2, but the current value decreases at the time of completion of bonding, so a reference for bonding is provided. After the joining is completed, the substrates are gradually cooled for about 20 minutes in order to prevent stress cracking due to the difference in thermal conductivity between the substrates 1 and 2.

In this way, at the time of joining, if the potential difference between the electrode 21 and the vibrating plate 5 is eliminated by the terminal plate 115 and the spring 114, the electric field disappears and discharge or field emission can be prevented, so that a large current flows between the electrode 21 and the vibrating plate 5. Does not flow, and the melting of the electrode 21 can be prevented. Further, since the electrostatic attraction due to the electric field does not act on the diaphragm 5, residual stress does not occur on the diaphragm 5 after fixing the periphery thereof. Further, the insulating film 24 is charged by the movement of electric charges from the diaphragm 5, and the diaphragm 5 is charged in the electric field.
Although peeling is performed by receiving electrostatic attraction force in the direction of, the peeling of the insulating film 24 can be prevented by setting the electrode 21 and the diaphragm 5 at the same potential.

(Embodiment 10) FIG. 26 is a schematic view showing another embodiment of the anodic bonding method of the present invention, which is a sectional view of a bonding apparatus used for this bonding method and both substrates being bonded. FIG. 27
FIG. 3 is a plan view of the joining device.

In this embodiment, the terminal 11 composed of a coil spring is used.
6 is used to make contact with each electrode 21. Other configurations are the same as those in FIG.

The material of the terminal 116 is made of SUS for the purpose of withstanding the high temperature at the time of joining. Usually, SUS material is not preferable as a terminal material because of resistance due to the oxide film on the surface, but in anodic bonding, the purpose is to apply a high voltage and to make it equipotential. Is obtained. By using each terminal 16 as an independent coil spring, the warp of the substrate due to heating at the time of anodic bonding and the terminal 1
It is possible to prevent defective conduction with the electrode 21 due to abrasion of the electrode 16.

(Embodiment 11) FIG. 28 is a plan view of an anodic bonding apparatus according to still another embodiment, and FIG. 29 is a plan view showing an arrangement relationship between electrodes on a second substrate and common electrodes. Note that the insulating film is omitted in FIG.

In the present embodiment, a plurality of sets (two sets in the example) of electrodes 21 for ink jet heads and individual sets of each set are formed on one borosilicate glass substrate 2A by badge processing by photolithography. A common electrode 120 that connects the electrodes 21 is simultaneously formed. The common electrode 120 has lead portions 121a and 121b connected to the terminal portions 23 of all the electrodes 21 of each set. Further, a single silicon substrate (not shown) bonded to the borosilicate glass substrate 2A has a plurality of sets of elements (nozzle, discharge chamber, vibrating plate, orifice, Ink cavities) are simultaneously processed at corresponding positions. Then, at the time of bonding, one terminal 116 made of a coil spring similar to that shown in FIG. 26 is brought into contact with the common electrode 120 and is electrically connected to the anode-side bonding electrode plate 111. Therefore, all the electrodes 21 of each set and all the diaphragms of each set can be made to have the same potential, and the same effect as that of the above-described embodiment can be obtained.

After joining, the ink jet heads are cut by dicing, and each set of electrodes 21 to common electrode 1 is cut.
20 is separated at the connection ends of the lead portions 121a and 121b.

(Embodiment 12) FIG. 30 is a sectional view of an anodic bonding apparatus according to still another embodiment.

In this embodiment, three substrates 1, 2 and 3 are anodically bonded at the same time. Of these, the first substrate 1 is a silicon substrate, and the second and third substrates 2, 3
Is a borosilicate glass substrate. The third substrate 3 is simply a nozzle hole 4, a discharge chamber 6, an orifice 7, an ink cavity 8
Since it serves as a lid of the borosilicate glass substrate, the bonding accuracy is lower than that of the borosilicate glass substrate, and the bonding of soda glass is also sufficient. However, if the third substrate 3 is also a borosilicate glass substrate, anodic bonding can be performed. The reliability can be improved.

Therefore, in this embodiment, the upper and lower bonding electrode plates 1 to be brought into contact with the second and third borosilicate glass substrates 2 and 3.
11 and 112 are connected to the negative side of the power source 113, and
The silicon substrate 1 and the electrode 21 on the second borosilicate glass substrate 2 are connected to the positive side of the power source 113 and are simultaneously anodically bonded. Therefore, by this simultaneous anodic bonding, the time required for heating and gradually cooling the substrates 1, 2, and 3 can be saved, and the bonding time can be greatly shortened, and the silicon substrate 1 as in Examples 9 to 11 can be shortened. It is possible to prevent the surface from being contaminated by direct contact with the upper bonding electrode plate 111.

In the following thirteenth and fourteenth embodiments, there is shown a structural example for preventing dust from entering the gap portion having the above-mentioned structure. Here, an electrostatic actuator will be described as an example, but the same structure can be used even in the case of an inkjet head.

(Embodiment 13) FIG. 31 is a sectional view of an electrostatic actuator according to this embodiment, and FIG. 32 is a plan view thereof.

As is clear from the above-mentioned embodiment,
The first substrate 1 and the second substrate 2 are anodically bonded or directly bonded to Si with a predetermined gap length. Since the temperature at the time of anodic bonding is high, the air in the gap 16 expands, and when the temperature drops to room temperature after bonding, the pressure in the gap 16 becomes below atmospheric pressure, so that the diaphragm 5 moves toward the electrode 21. Problems such as short circuit due to contact with the flexible electrode 21 or unnecessary stress on the diaphragm 5 occur. If the gap 16 is left open to the atmosphere in order to prevent this, dust is attracted by the action of static electricity, and the dust adheres to the electrode 21 to fluctuate the vibration characteristics of the diaphragm 5.

Therefore, in this embodiment, the gap portion 16 is opened to the atmosphere through the passage 18 and the passage 1
The outlets 19a and 19b of No. 8 are sealed with a sealing agent such as an epoxy type which has a high viscosity when the substrates 1 and 2 are cooled to room temperature after anodic bonding. In the figure, 20 indicates the seal member. 23 is a terminal portion of the electrode 21, 41 is a SiO ₂ film which is an insulating film formed on the substrate 1, 102 is an oscillation circuit, 1
Reference numeral 06 is a metal film provided to connect one terminal of the oscillation circuit 102 to the substrate 1. The passage 18 is provided so as to circulate around the electrode 21.

Since the silicon substrate constituting the substrate 1 has a high thermal conductivity, the pressure in the gap portion 16 does not become high even if it is sealed with a thermoplastic resin, and the sealing member 20 has a high viscosity. , Does not flow into the passage 18.

Therefore, according to the structure of this embodiment, since the gap portion 16 is open to the atmosphere through the passage 18 during the anodic bonding, the gap portion 1 is heated by the anodic bonding.
Since the pressure inside 6 does not rise, and since the outlet of the passage 18 is sealed by the seal member 20 after the temperature drops after anodic bonding, dust does not enter the gap portion 16, The above inconvenience does not occur.

(Embodiment 14) FIG. 33 is a sectional view of an electrostatic actuator according to another embodiment.

In this embodiment, the electrode 21 is provided on the lower surface of the diaphragm 5.
The second electrode 46 is provided so as to face the above. The second electrode 46 is made of a thin film of Cr or Au.

Since the electrostatic actuator functions as a capacitor, when a voltage V is applied to the counter electrodes 21 and 46, the voltage Vc between the counter electrodes 21 and 46 due to charge / discharge of electric charges is Vc = V ( 1-exp (-t / T)) Vc during discharge = Vexp (-t / T) However, T becomes exponential as shown by the time constant, and when the time constant T is large, the rising speed of Vc You can see that it will be late. The time constant T is given by RC, where R is resistance and C is capacitance. Since the resistance of silicon is higher than that of metal, a Cr or Au thin film electrode 46 having a low resistance value is required for high speed driving.
Are formed on the diaphragm 5 and the time constant is reduced to improve the response of the actuator.

(Embodiment 15) FIG. 34 is a sectional view of an ink jet head according to still another embodiment of the present invention.

In this embodiment, the gap G formed in the lower portion of the diaphragm 5 is secured by the thickness of the photosensitive resin layer or the adhesive layer 200. That is, the photosensitive resin layer or the adhesive layer 20 is formed around the electrode 21 of the second substrate 2.
0 is printed and patterned, and the second substrate 2 and the first substrate 1 are bonded and laminated and joined. In particular,
Soda glass was used as the second substrate 2, and the configuration was the same as that of the second embodiment. Then, photosensitive polyimide is used as the photosensitive resin, and a thickness of 1 is provided around the electrode 21 of the substrate 2.
The photosensitive resin layer 200 was formed by printing and patterning with a thickness of μm. On the other hand, as in the case of Example 2, the lower surface of the first substrate 1 was a silicon substrate having a smooth surface, and this substrate 1 and the above-described substrate 2 were laminated and bonded at 250 ° C. Therefore, in the case of the photosensitive resin, the gap length G between the diaphragm 5 and the electrode 21 is 1.4 μm. In the case of an adhesive, an epoxy adhesive was used. Its thickness is 1.5 μm,
The substrate 1 and the substrate 2 were laminated and bonded at 100 ° C. In this case, the gap length G is slightly less than 1.9 μm. In the case of an adhesive, the substrate 1 and the substrate 2 must be pressed at the time of joining, so that the gap length G becomes smaller by that amount, unlike the case of a photosensitive resin.

A predetermined gap length can be ensured also by such a gap holding means, and the ink jet head can be driven at a low voltage almost the same as in Example 2 and showed good printing performance.

The photosensitive resin may be not only the above-mentioned polyimide but also acrylic, epoxy, etc., and the firing temperature is adjusted according to each resin. In addition, other adhesives such as acrylic, cyano, urethane,
Various materials such as silicon type can be used.

[0153]

As described above, according to the present invention, when the first substrate and the second substrate are anodically bonded, the potential between the diaphragm and the electrode is changed, so that the diaphragm and the electrode are connected. Discharge and field emission can be prevented, a predetermined gap length can be accurately maintained, and residual stress of the diaphragm and peeling of the insulating film do not occur.

By providing a passage communicating with the outside in the gap portion between the diaphragm and the electrode, the pressure rise in the gap portion is eliminated at the time of anodic bonding, and the outlet of the passage is sealed after the anodic bonding. It is possible to prevent dust from entering the gap.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of an inkjet head of the present invention.

FIG. 2 is a sectional side view of the first embodiment.

FIG. 3 is a view taken along the line AA of FIG.

FIG. 4 is an exploded perspective view showing a second embodiment of the inkjet head of the present invention.

FIG. 5 is a sectional side view of the second embodiment.

6 is a view taken along the line BB of FIG.

FIG. 7 is an exploded perspective view showing a third embodiment of the inkjet head of the present invention.

FIG. 8 is an enlarged perspective view showing a part of the third embodiment.

FIG. 9 is a manufacturing process diagram of the first substrate in the third embodiment.

FIG. 10 is a diagram showing a dimensional relationship of portions of a diaphragm in the third embodiment.

FIG. 11 is a manufacturing process diagram of a second substrate in the third embodiment.

FIG. 12 is a perspective view of a first substrate in a fourth embodiment of the inkjet head of the present invention.

FIG. 13 is a manufacturing process diagram for a first substrate according to the fourth embodiment.

FIG. 14 is an exploded perspective view showing a fifth embodiment of the inkjet head of the present invention.

FIG. 15 is a manufacturing process diagram of the first substrate in the fifth embodiment.

FIG. 16 is a perspective view of a first substrate in a sixth embodiment of the inkjet head of the present invention.

FIG. 17 is a manufacturing process drawing of the first substrate in the sixth embodiment.

FIG. 18 is a diagram showing a method of electrochemical anisotropic etching in the sixth embodiment.

FIG. 19 is a perspective view of a first substrate in a seventh embodiment of the inkjet head of the present invention.

FIG. 20 is a manufacturing process diagram of the first substrate in the seventh embodiment.

FIG. 21 is a perspective view of a first substrate in an eighth embodiment of the inkjet head of the present invention.

FIG. 22 is a manufacturing process diagram of the first substrate in the eighth embodiment.

FIG. 23 is a diagram showing the relationship between B (boron) concentration and etching rate in alkaline anisotropic etching.

FIG. 24 is a cross-sectional view showing an embodiment of an anodic bonding apparatus used in the anodic bonding method of the present invention.

FIG. 25 is a plan view of the anodic bonding apparatus of FIG. 24.

FIG. 26 is a cross-sectional view showing another embodiment of the anodic bonding apparatus used in the anodic bonding method of the present invention.

27 is a plan view of the anodic bonding apparatus of FIG. 26. FIG.

FIG. 28 is a plan view showing still another embodiment of the anodic bonding apparatus used in the anodic bonding method of the present invention.

29 is a plan view of the second substrate of FIG. 28. FIG.

FIG. 30 is a sectional view showing still another embodiment of the anodic bonding apparatus used in the anodic bonding method of the present invention.

FIG. 31 is a sectional view showing an embodiment of the dust prevention method of the present invention.

32 is a plan view of the embodiment of FIG. 31. FIG.

FIG. 33 is a sectional view showing another embodiment of the dust prevention method of the present invention.

FIG. 34 is a cross-sectional view showing another embodiment of the distance maintaining means of the present invention.

FIG. 35 is a schematic view showing a printer incorporating the ink jet head of the first embodiment of the present invention.

[Explanation of symbols]

1st substrate 2 Second substrate 3rd substrate 4 nozzle holes 5 diaphragm 6 discharge chamber 7 orifice 8 ink cavities 9 Vibration chamber 10 inkjet head 15 recess 21 electrodes 24 Insulating film

─────────────────────────────────────────────────── ─── Continuation of front page (31) Priority claim number Japanese Patent Application No. 4-181240 (32) Priority date July 8, 1992 (July 7, 1992) (33) Priority claim country Japan (JP) (72) Inventor Shuji Koeda 3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation (56) References JP-A-4-22642 (JP, A) JP-A-54-146633 (JP, 146633) A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/16 B41J 2/045 B41J 2/055

Claims (4)

(57) [Claims] 1. A first substrate having a nozzle hole for discharging ink droplets, a discharge chamber communicating with each of the nozzle holes, and a vibrating plate forming at least one wall of the discharge chamber. A method of manufacturing an inkjet head, comprising: a drive unit that causes deformation of the diaphragm; and a second substrate on which an electrode that causes the drive unit to deform the diaphragm by an electrostatic force is formed. A method of manufacturing an inkjet head, comprising a step of changing the potentials of the vibration plate and the electrode when the second substrate is anodically bonded. 2. The method of manufacturing an ink jet head according to claim 1, wherein the potential of the electrode is set to be equal to the potential of the diaphragm. 3. A first substrate having a nozzle hole for ejecting ink droplets, an ejection chamber communicating with each of the nozzle holes, and a vibrating plate forming at least one wall of the ejection chamber. A method of manufacturing an inkjet head, comprising: a driving unit that causes the diaphragm to deform; and a second substrate on which an electrode that causes the driving unit to deform the diaphragm by an electrostatic force is formed. Forming a common electrode to be connected on the second substrate; changing the potentials of the diaphragm and the electrode when anodic bonding the first substrate and the second substrate; and after anodic bonding And a step of separating the common electrode from the electrode, the method of manufacturing an inkjet head. 4. A gap portion communicating with the atmosphere through a passage is provided between a diaphragm formed on the first substrate and an electrode formed on the second substrate, and the passage is formed after anodic bonding. The method for manufacturing an inkjet head according to any one of claims 1 to 3, wherein the outlet is sealed with a sealing member.