JPH10244667A - Ink jet head and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head which is free from an adverse effect on an electrode by a generated cavity and ensures reliable ink discharge characteristics and the smooth joining of a silicone substrate with a glass substrate as well as a method for manufacturing the ink jet head. SOLUTION: A first substrate 1 is of silicone and has an oscillating plate 12 formed at the bottom of a recessed part 11 making up a flow path. This oscillating plate 12 has a lower face which is a planished smooth face. Further, a seconds substrate 2 joining with the lower face of the first substrate 1 is of glass, and has a recessed part 25 of a desired gap formed by etching for mounting an electrode 21. The first substrate 1 is joined with the second substrate 2 through a layer into which an alkali ion is introduced.

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, and more particularly to an ink jet head for joining a plurality of substrates by anodic bonding and a method for manufacturing the same.

[0002]

2. Description of the Related Art There is an ink jet recording apparatus which uses a vibration plate as an ink jet head actuator element for pressurizing ink and pressurizes and discharges ink by rapidly changing the vibration plate. A first substrate provided with a diaphragm and a second substrate provided with electrodes for driving the diaphragm are joined by a gap film (oxide film, Pyrex) having a desired thickness,
Alternatively, an electrostatic ink jet head having a structure in which a gap is formed on the bottom surface of the diaphragm or a structure in which a gap is formed by etching Pyrex glass of the second substrate and joined together (for example, JP-A-6-71882). Are disclosed.

When a glass (bulk) substrate is used as an electrode substrate for manufacturing an actuator and a gap is formed on the substrate by wet etching which is a process by a chemical reaction, a hydrogen fluoride solution (H
A desired gap is formed by using a buffered fluorine (buffered hydrofluoric acid) obtained by mixing F) and an ammonium fluoride solution (NH ₄ F). This solution, unlike a solution obtained by simply diluting concentrated hydrofluoric acid with pure water, has a feature that since it contains a large amount of salt, it can be etched without swelling or peeling off the resist material.

[0004]

However, when this etching solution is used for etching, there is a problem in that cavities (voids) are formed on the etched surface, although there are variations due to the glass substrate. This is because, considering the operation of the actuator, the effective electrode area is reduced due to the presence of the nest, and the force generated by the actuator is reduced.

[0005] Further, the electrode area as an actuator varies depending on how the nest enters, which has a very significant effect on the ink discharge characteristics. Therefore, the glass substrate was etched using a substrate having a small amount of alkali ions, so that etching could be performed without generating cavities. Here, a new bonding of the silicon substrate and the glass substrate (anode (Joining) has a disadvantage that the joining time is long.

The present invention has been made in view of the above points, and has good ink discharge characteristics without affecting the electrodes due to the occurrence of cavities. Further, good bonding between the silicon substrate and the glass substrate can be achieved. It is an object of the present invention to provide a possible inkjet head and a method for manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided an ink jet head comprising: a first substrate provided with a flow path and a diaphragm; and a second substrate provided with electrodes for driving the diaphragm. The present invention is characterized by a structure in which the layers are joined via the above-mentioned layers, so that good etching can be performed without generating cavities on the etching surface of the glass substrate, and a good base can be obtained when forming the electrodes.

According to a second aspect of the present invention, in the inkjet head of the first aspect, the layer into which the alkali ions have been introduced is silicon oxide on the silicon surface.
An efficient (time-saving) anodic bonding can be obtained.

According to a third aspect of the present invention, there is provided the ink jet head according to the second aspect, wherein the silicon oxide into which the alkali ions are introduced doubles as a gap forming layer between the first substrate and the second substrate. This eliminates the need to newly provide a gap film forming layer and reduces the number of steps.

According to a fourth aspect of the invention, there is provided a method of manufacturing an ink jet head according to any one of the first to third aspects, wherein the resist layer on which the electrodes are formed is also used as a mask layer when introducing alkali ions. Thus, the process is shortened without requiring a new process for introducing alkali ions.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an ink jet head according to the present invention, when a voltage is applied to an electrode, an attractive force is generated between the electrode and a diaphragm arranged opposite to the electrode. The diaphragm is deformed by this, and the ink is pressurized by the deformation of the diaphragm to discharge ink droplets from the nozzle holes.

(Embodiment 1) FIG. 1 is an exploded perspective view showing a first embodiment of an ink jet head according to the present invention, and FIG. 2 is a view showing a manufacturing process thereof.
Although the substrate 1 and the second substrate 2 are shown in an exploded manner, they actually have a laminated structure in which they are overlapped and joined. The first substrate 1 is a silicon substrate, and a diaphragm 12 is provided at the bottom of a concave portion 11 forming a flow path and the like. The lower surface of the diaphragm 12 is a smooth surface by mirror polishing.
As the second substrate 2 to be bonded to the lower surface of the first substrate 1, a glass substrate (for example, Pyrex # 7070) is used, and a concave portion 25 for mounting the electrode 21 on the second substrate 2 is etched as desired. Form in the gap. As a formation method,
As shown in FIG. 2, the photoresist pattern 3 is formed so that a slightly larger concave portion is formed so that the electrode 21, the lead portion 22, and the lead terminal portion 23 can be mounted therein.
To form

Next, a desired concave portion 25 is formed in the exposed portion 2a of the glass substrate 2 by wet etching (FIG. 2B), and the photoresist is etched (not shown). BHF (hydrofluoric acid 6%,
Etching using ammonium fluoride (30%). If the recess 25 is to be deeply etched, a metal mask is used on the surface of the glass substrate 2 to prevent side etching. As a result, a good electrode formation portion 25 can be obtained without burrs on the etched surface. This is presumably because Na ions (alkali) are not present in the components in the glass substrate, so that the concave portions 25 can be formed by etching without generating cavities because of excellent chemical durability.

Next, the photoresist etching recess 25 is formed.
In order to form the electrodes 21, 22, and 23, electrodes (eg, ITO, Pt, etc.) are deposited on the entire surface, and after the photoresist pattern 3 'is formed, the electrodes are formed (FIG. 2).
(C)). Next, alkali ions are introduced into the entire surface of the glass substrate 2 by ion implantation while leaving the resist 3 'on the electrode as it is. As a result, alkali ions are implanted only in portions other than the resist mask portion 3 '(FIG. 2D). Next, as the last step, the entire surface of the photoresist 3 'on the electrodes 21, 22, 23 is etched (FIG. 2E).
The reason for introducing alkali ions into the glass substrate 2 is as follows.
After the first substrate 2 and the second substrate 2 are formed, they are efficiently and favorably joined. There are various joining methods shown in Table 1 for joining, but it is necessary to select the joining method depending on the material to be joined.

[0015]

[Table 1]

Anodic bonding is used for bonding with the material according to the present invention. However, there is a disadvantage that a longer time is required for joining than in the past, and it is necessary to improve the disadvantage. The anodic bonding is performed on a glass substrate 2 containing alkali ions and a silicon substrate 1
Are heated to 300 ° C. to 400 ° C., and a negative voltage of about 500 V is applied to the glass (Pyrex) side to generate an electrostatic attraction between the glass and the silicon, thereby forming a chemical bond at the interface to join the glass and silicon. In anodic bonding,
It is said that the larger the amount of alkali ions, the greater the electrostatic attraction, and that bonding can be performed at a low temperature.

In the glass substrate 2 used in the present invention,
Does not contain Na ions. Therefore, alkali ions (Na +, K +, Li +, etc.) are introduced into the interface between the first substrate 1 and the second substrate 2 and provided as a layer. As an introduction method, ion implantation was used. Alkali ions are not limited to the alkali ions described above,
Specifically, Na + and K + are desirable. The implantation energy in the ion implantation method is 60 keV to 1 Mev.
The dose is preferably in the range of 10 ¹² to 10 ¹⁷ cm ² , and more preferably, the implantation energy is 80 kev to ² cm ^2.
It is preferable that the dose is 00 keV and the dose is 10 ¹⁵ to 10 ¹⁷ cm ⁻² .
Note that the introduction layer may be provided at a very shallow place on the upper surface of the second substrate 2.

(Embodiment 2) In the ink jet head according to the second embodiment of the present invention, in forming the recess 25 of the second substrate 2, the gap depth is set to BHF in the process of the first embodiment. It was formed to a depth of 1.5 microns. Note that the glass substrate 2 is a substrate in which a nickel film is deposited on the upper surface of the substrate 2, and after opening nickel at portions where the electrodes 21, 22, and 23 are formed, the glass substrate 2 is etched. As a result, as in the first embodiment, a good etched surface was obtained.

(Embodiment 3) FIG. 3 shows a manufacturing process of a first substrate 1 as a third embodiment. Both surfaces of the first substrate (silicon) are mirror-polished to produce a 200-micron silicon substrate 31 (FIG. 3A), a thermal oxide film is applied to the silicon substrate 31, and a thickness of 2 Micron oxide films 32a and 32b are formed (FIG. 3)
(B)). The oxide films 32a and 32b are used as an etching resistant material.

Next, a photoresist pattern (not shown) corresponding to the shape of the nozzle, the flow path and the like is formed on the oxide film 32a on the upper surface, and the exposed portion of the oxide film 32a is removed by etching with BHF. The resist pattern is removed (FIG. 3C). Next, the diaphragm 5 having a desired thickness is formed by performing anisotropic etching with an alkaline solution.
(D)). Next, the oxide film 32 on the lower surface of the silicon substrate 31
Alkali ions are introduced into the entire surface of b (FIG. 3E).
Next, since the oxide film 32b is used as a gap film, when the oxide film 32b is thicker than a desired film thickness, the oxide film 32b is used.
To a desired thickness by etching. Next, the oxide film 32
A photoresist pattern (not shown) having a shape corresponding to the diaphragm 5 is formed on the substrate b, and the exposed portion of the oxide film 32b is removed by etching with BHF, and the resist pattern is removed. At the same time, all of the oxide film 31a remaining on the surface of the substrate 31 is removed (FIG. 3F). Thus, the manufacturing process of the first substrate in this embodiment is completed.

As described above, according to the present invention, the oxide film 32b on the back surface of the silicon substrate can be used as a gap layer without depositing a film serving as a gap. In the joining, the joining was performed using a glass substrate from which the introduction of alkali ions into the glass substrate 2 in the production of the second substrate in the first embodiment was omitted.

Hereinafter, main process conditions in this embodiment will be described. Gap width: glass substrate 0.5, 1.5 microns, glass substrate implantation energy / dose: 100 keV /
10 ¹⁵ cm ^2, anodic bonding condition board size: 20 × 20 mm, heating temperature: 350 ° C., the applied voltage: -400 V,

The surface properties of the glass substrate obtained by the etching of the examples obtained as described above and the bonding completion time in anodic bonding were evaluated. Table 2 shows the results. As can be seen from the results, the alkali ions according to the present invention were applied to the first substrate and the second substrate after the completion of the processing.
By introducing it at the interface between the substrate and the second substrate, no burrs occur on the etched surface, and the bonding time during anodic bonding is dramatically improved.

[0024]

[Table 2]

[0025]

According to the ink jet head of the first aspect, the first substrate 1 and the second substrate 2 are joined via the layer into which the alkali ions are introduced after the etching of the glass substrate. A good etching process can be performed without generating cavities on the etched surface, and a good underlayer can be obtained at the time of electrode formation.

According to the ink jet head of the second aspect, since alkali ions are introduced into the silicon oxide on the silicon surface, it can be used as a gap film and an efficient (time-saving) anodic bonding can be obtained. Also,
No new gap formation is required. As a further effect, the anodic bonding technique can be used by introducing alkali ions without defining the thickness of the silicon oxide.

According to the third aspect of the invention, since the gap head forming layer can be used without newly providing the same, the number of steps can be reduced.

According to the method of manufacturing an ink jet head according to the fourth aspect, since a mask layer is also used when introducing alkali ions, a new step of introducing alkali ions is not required, and thus the steps can be shortened.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of an ink jet head according to the present invention.

FIG. 2 is a diagram showing the manufacturing process.

FIG. 3 shows a method for manufacturing the first substrate 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate (silicon board | substrate), 2 ... 2nd board | substrate (glass board), 11 ... recessed part, 12 ... diaphragm, 21 ... electrode,
22: lead portion, 23: terminal, 24: insulating layer, 25: concave portion.

Claims (4)

[Claims] 1. An ink jet head manufactured by using anodic bonding, comprising: a first substrate provided with a flow path and a diaphragm; and a second substrate provided with an electrode for driving the diaphragm. An ink jet head, wherein the first substrate and the second substrate are joined via a layer into which alkali ions have been introduced. 2. The ink jet head according to claim 1, wherein the layer into which the alkali ions are introduced is silicon oxide on a silicon surface. 3. The ink jet head according to claim 2, wherein the silicon oxide into which alkali ions have been introduced also serves as a gap forming layer between the first substrate and the second substrate. 4. The method of manufacturing an ink jet head according to claim 1, wherein the resist layer on which the electrodes are formed is also used as a mask layer when introducing alkali ions.