JPH09234873A - Manufacture of ink jet head and ink jet printer using that head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out stabilized high quality printing by a method wherein stability of discharge is increased by improving precision in thickncess of a diaphragm. SOLUTION: A Si substrate wherein a boron dope layer 46 is formed, and an oxide film 42 is patterned is etched just before reaching the boron dope layer 46 with 35wt.% potassium hydroxide aqueous solution. Then, etching is continued with 5wt.% potassium hydroxide aqueous solution, and the etching is stopped. Further, the etching is continued, and the diaphragm is etched to a specific thickness. By this method surface roughening of an etching surface 81 to stop of etching is inhibited, and the surface roughening is reduced by additional etching from the etching stopped surface 82. By such the effect, surface roughening of the etching surface 83 is further reduced, and precision in thickness of the diaphragm 5 can be made to be within 2±0.025μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is obtained by a method of manufacturing an ink jet head, which is a main part of an ink jet head recording apparatus in which ink droplets are ejected only when recording is required, and adheres to the surface of a recording paper. And an inkjet printer having the inkjet head.

[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 required, is currently in the mainstream because it does not require recovery of ink droplets unnecessary for recording.

In this ink-on-demand type ink jet head recording apparatus, there is an ink jet head recording apparatus which uses electrostatic force as a driving means as a method for ejecting ink (Japanese Patent Laid-Open No. 6-71882). The method has the advantages of small size, high density, high print quality, and long life.

In the ink jet head using the electrostatic force as a driving source, the mechanical deformation characteristics of the diaphragm have a great influence on the ink ejection characteristics, and it is necessary to control the thickness of the diaphragm with high accuracy. Conventionally, when a diaphragm is formed by etching a Si substrate, a method of controlling the etching time to control the thickness of the diaphragm has been used. However, as the size of the inkjet head becomes smaller and the performance of the diaphragm becomes smaller, the diaphragm becomes thinner and more accurate thickness is required, which makes it difficult to control the etching time alone. Therefore, the etching stop technique as disclosed in JP-A-6-71882, page 20, line 15 or JP-A-53-63880, page 10, line 46 is used to utilize the slow etching rate of the p-type impurity layer. , A method has been adopted in which only a p-type impurity layer is left by etching to form a thin film to be a vibration plate.

[0005]

However, in the above-described method for manufacturing the diaphragm of the ink jet head, the diaphragm thickness is large at the time when the etching rate of the p-type impurity layer is reduced, and the vibration of 2 micron is generated. The thickness unevenness was 1 micron with respect to the plate thickness. Therefore, the rigidity of the diaphragm is not constant within the diaphragm, and there is a problem that the ejection performance is not stable.

Therefore, the present invention is intended to solve the above-mentioned problems, and an object of the present invention is to improve the thickness accuracy of a diaphragm and to provide an ink jet head of excellent print quality with stable ink ejection performance. The present invention provides a method of manufacturing the same.

[0007]

According to the method of manufacturing an ink jet head of the present invention, at least one of a single or a plurality of nozzle holes for ejecting ink droplets, an ejection chamber connected to each of the nozzle holes, and an ejection chamber is provided. Diaphragm that composes the wall of
A method of manufacturing an inkjet head, comprising: a driving unit that deforms the diaphragm, the driving unit including an electrode that deforms the diaphragm by an electrostatic force, and the diaphragm being a Si substrate including a high-concentration p-type impurity layer, The surface of the Si substrate opposite to the surface on which the high-concentration p-type impurity layer is formed is etched with a low-concentration potassium hydroxide aqueous solution to form a vibration plate by leaving the high-concentration p-type impurity layer, and the remaining vibration plate. Is etched with a low-concentration aqueous potassium hydroxide solution.

In the method of manufacturing an ink jet head, Si up to the vicinity of the high-concentration p-type impurity layer on the surface of the Si substrate opposite to the surface on which the high-concentration p-type impurity layer is formed.
The substrate is etched with a high-concentration potassium hydroxide aqueous solution, and the etching from the vicinity of the high-concentration p-type impurity layer to the high-concentration p-type impurity layer is performed with a low-concentration potassium hydroxide aqueous solution to leave the high-concentration p-type impurity layer. And a vibration plate formed by using the above-mentioned high-concentration potassium hydroxide and low-concentration potassium hydroxide, and further characterized by etching with a low-concentration potassium hydroxide aqueous solution. .

Further, the concentration of the low-concentration aqueous potassium hydroxide solution is 0.5 to 10 w% (weight%, hereinafter the same in this specification), or the concentration of the high-concentration aqueous potassium hydroxide solution is The concentration is 30 to 55 w%.

Further, the high-concentration p-type impurity layer is a high-concentration boron-doped layer.

Further, it is an ink jet printer having an ink jet head obtained by the above-mentioned manufacturing method.

[0012]

In an ink jet head manufactured by anisotropically etching a Si substrate, the phenomenon that the etching rate in the high-concentration p-type impurity layer is extremely lowered is used to make a thin film by etching the high-concentration p-type impurity layer. As a result, the diaphragm with high plate thickness accuracy is formed of the high-concentration p-type impurity layer.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below 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 a face inkjet type in which ink droplets are ejected from nozzle holes provided on the surface of the substrate. 2 is a side sectional view of the assembled whole device, and FIG. 3 is a view taken along the line AA ′ of FIG. The ink jet head of this embodiment has a laminated structure in which three substrates 1, 2 and 3 having the structure described in detail below are stacked and joined.

The intermediate first substrate 1 is a Si substrate,
A concave portion 7 that forms a discharge chamber 6 having a bottom wall as a vibration plate 5, a narrow groove 9 for an ink inlet that forms an orifice 8 provided at a rear portion of the concave portion 7, It has a concave portion 11 that constitutes a common ink cavity 10 for supplying ink to the ejection chamber 6. First
An oxide film 12 of 0.1 micron is formed on the entire surface of the substrate 1 by thermal oxidation to form an insulating film. This is to prevent dielectric breakdown and short circuit during ink jet driving.

The second substrate 2 bonded to the lower surface of the first substrate 1 is made of borosilicate glass, and the recess 14 for mounting the electrode 13 on the substrate 2 is etched by 0.3 μm. The gap G, that is, the gap G, between the vibrating plate 5 and the electrode 13 arranged to face the vibrating plate 5 is formed. The concave portion 14 is formed in a pattern having a slightly larger shape similar to the shape of the electrode portion so that the electrode 13, the lead portion 15 and the terminal portion 16 can be mounted therein. The electrode 13 is manufactured by sputtering ITO in the recess 14 by 0.1 μm to form an ITO pattern. Therefore, the gap G after the anodic bonding of the first substrate 1 and the second substrate 2 in this embodiment is 0.2 μm.

Further, a Si substrate 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 communicates with the recess 7 for the discharge chamber 6. Nozzle holes 17 are provided respectively, and the ink supply port 18 is provided so as to communicate with the recess 11 for the ink cavity 10.
Is provided.

The operation of the ink jet head configured as described above will be described. When a pulse potential of 0V to 35V is applied to the electrode 13 by the oscillator circuit 19 and the surface of the electrode 13 is positively charged, the lower surface of the corresponding diaphragm 5 is negatively charged. Therefore, the diaphragm 5 bends downward due to the electrostatic attraction. Next, turn off the electrode 13.
Then, the diaphragm 5 is restored. Therefore, the pressure in the ejection chamber 6 rapidly rises, and the ink droplets 2 are discharged from the nozzle holes 17.
0 is ejected toward the recording paper 21. Next, when the diaphragm 5 bends downward again, ink is supplied from the ink cavity 10 into the ejection chamber 6 through the orifice 8. The substrate 1 and the oscillator circuit 19 are connected to each other through a window (not shown) of the oxide film 12 formed in a part of the substrate 1 by dry etching.

The vibrating plate 5 in the ink jet head of this embodiment is a high-concentration p-type impurity layer and has a high concentration p-type.
The type impurity layer has the same thickness as the desired diaphragm thickness. Although boron, gallium, aluminum, and the like are used as the impurities forming the high-concentration p-type impurity layer, boron is generally used as the impurity forming the p-type impurity layer in the semiconductor field, and also in this embodiment. Boron was used as an impurity. Therefore, the case where the high-concentration p-type impurity layer is a high-concentration boron-doped layer will be described below. The etching rate in Si etching with alkali is high (about 5 × 10 ¹⁹⁾ when the dopant is boron.
The etching rate becomes very small in the region of (cm ⁻³ or more) (FIG. 6). In this embodiment, by utilizing this, the diaphragm forming region is a high-concentration boron-doped layer, and the etching rate at the time when the boron-doped layer is exposed when the ejection chamber and the ink cavity are formed by alkaline anisotropic etching. The vibrating plate 5 is manufactured to have a desired plate thickness by the so-called etch stop technique, which is extremely small.

In the method for manufacturing the first substrate 1 of the ink jet head in this embodiment, the 2 μm vibrating plate 5 is used as the impurity diffusion source of B ₂ O ₃ in the diffusion process diagram of the first substrate of FIG. The case of forming will be described in detail.

First, both surfaces of a Si substrate having a (110) plane orientation are mirror-polished to form a substrate 41 having a thickness of 180 μm.
Is produced (FIG. 4A). The Si substrate 41 is set in a thermal oxidation furnace, and the temperature is set to 1100 degrees Celsius in an atmosphere of oxygen and water vapor.
A thermal oxidation process is performed for 4 hours to form an oxide film 42 of 1.2 μm on the surface of the substrate 41 (FIG. 4B). Next, in order to remove the oxide film 42 on the surface 43 on which the boron-doped layer is formed, the surface 4 on which the boron-doped layer is formed on the substrate 41 is removed.
3 is coated with a resist on the surface 44 on the opposite side, and the oxide film 4 on the surface 43 on which a boron-doped layer is formed using the resist as a protective film
2 is removed by etching with a hydrofluoric acid aqueous solution, and the resist is peeled off (FIG. 4C). A diffusion agent 45 in which 3.15% by weight of B ₂ O ₃ as a diffusion source is dispersed in an organic solvent is added to the oxide film 4.
The surface 43 from which 2 was removed was spin-coated at 2000 rpm for 1 minute, and the temperature was adjusted to 14 degrees Celsius in a clean oven.
Bake at a temperature of 0 degrees for 30 minutes (FIG. 4 (d)). At this time, the thickness of the diffusing agent is 1.2 μm.

The substrate 41 coated with the diffusing agent 45 is set in a thermal oxidation furnace and heated in an oxygen atmosphere at 600 ° C. to oxidize and remove the organic binder in the diffusing agent 45 and bake B ₂ O ₃ . . Subsequently, the inside of the furnace is made into a nitrogen atmosphere, the temperature is raised to 1100 degrees Celsius, the temperature is maintained for 12 hours, and boron is diffused into the Si substrate to form the boron-doped layer 46. At this time, the boron compound 47 is formed at the interface between B ₂ O ₃ and the substrate surface boron-doped layer (FIG. 4E).

A resist is coated on the side 44 opposite to the surface on which the boron-doped layer 46 is formed, and the diffusing agent 45 is removed by etching with a hydrofluoric acid aqueous solution (FIG. 4 (f)). The boron compound 47 appearing on the substrate surface has high etching resistance and cannot be removed by wet etching. Therefore, the following measures are taken. First, after removing the resist on the substrate 41,
The substrate 41 is set in an oxidation furnace, and an atmosphere of oxygen and water vapor,
Boron compound 47 is oxidized under the condition of 600 degrees Celsius for 1 hour, and can be etched with an aqueous solution of hydrofluoric acid. B ₂ O ₃ +
Chemically change to SiO ₂ . Since the oxidation temperature is low, diffusion does not progress, and the boron compound 47 can be removed by dry etching without being oxidized.
By oxidizing the boron compound 47 on the diffusion surface, B ₂ O ₃ + SiO
Thermal oxidation is further performed in the state of being chemically changed to ₂ to form a 1.2-micron oxide film 48 on the boron-doped layer side (FIG. 4G). Subsequently, resist patterning for forming the discharge chamber 6 and the ink cavity 10 is performed on the oxide film side 44, and the oxide film 42 is patterned by etching with a hydrofluoric acid aqueous solution. Then, the resist on the substrate 41 is removed (FIG. 4 (h)).

The above is the case where the high-concentration boron-doped layer is formed by the coating method, and as another means for forming the high-concentration doped layer, the boron diffusion plate is opposed to the Si substrate for thermal diffusion. There is.

After the Si substrate etching process, the oxide film 42 remaining on the substrate 41 is removed by etching using an aqueous solution of hydrofluoric acid, and then the oxide film 12 is formed on the surface of the substrate 41 by thermal oxidation to a thickness of 0.1 μm. , The first substrate 1 is manufactured.

A case where the etching process of the first embodiment of the present invention is performed in an etching solution which is a potassium hydroxide aqueous solution having a concentration of 5 w% will be described with reference to the etching process diagram of the first substrate of FIG. The substrate 41 (FIG. 5A) on which the oxide film 42 is patterned is immersed in an aqueous potassium hydroxide solution having a concentration of 10 w%, and Si etching is performed. When the substrate 41 is etched from the exposed portion 51 of Si on the side where the oxide film 42 is patterned and reaches the boron-doped layer 46, the etching is stopped and the boron-doped layer 46 remains so that the boron-doped layer 46 vibrates. It becomes the plate 5 (FIG. 5B). However, since the surface roughness of the etching surface 52 that occurs before reaching the boron-doped layer 46 is 10 μm, even if the surface roughness is reduced by the etching stop due to the decrease of the etching rate in the boron-doped layer 46, the etching stop Etching surface 53 on the surface of diaphragm 5 at the time (FIG. 5C)
The surface roughness is 1 micron. Therefore, the vibration plate 5 has a plate thickness unevenness of 1 micron due to the surface roughness of the etching surface 53. Here, the etching stop is defined as a state in which the bubbles generated from the etching surface are stopped during etching, and the stop of the generation of bubbles in the actual etching is determined as the etching stop.

State of the etching stop (FIG. 5)
Etching is further continued from (c)), and the etching amount is controlled so that the diaphragm 5 has a predetermined thickness (FIG. 5).
(D)). Boron-doped layer 4 as etching progresses
The boron concentration of 6 also increases toward the surface of the diffusion surface, and the etching rate also decreases as the boron concentration increases, so that the surface roughness of the etching surface 54 becomes smaller. Needless to say, the thickness of the boron-doped layer 46 is ensured by adjusting the diffusion conditions by predicting the etching amount of the additional etching.

By the additional etching from the state where the etching is stopped, the thickness accuracy of the diaphragm 5 is 2 ± 0.
It can be reduced to 3 microns or less, and the ink ejection performance of the inkjet head can be stabilized.

(Embodiment 2) Regarding the case where the etching step which is the second embodiment of the present invention is carried out in an etching solution which is a potassium hydroxide aqueous solution having a concentration of 35 w% and a potassium hydroxide aqueous solution having a concentration of 5 w% , First of FIG.
This will be described with reference to the substrate etching step diagram.

The boron-doped layer 46 is formed by the method described in the first embodiment, and the Si substrate 41 (FIG. 7A) in which the oxide film 42 is patterned is formed. However, the diffusion time will be changed to 8 hours. Next, the Si substrate 41 is 35w
% Potassium hydroxide aqueous solution, and etching is performed until just before reaching the boron-doped layer 46 (remaining about 10 μm) (FIG. 7B). In the etching with the 35 w% potassium hydroxide aqueous solution, the surface roughness of the etching surface 71 is suppressed to 1 micron or less. Next, the etching solution is changed to a 5 w% potassium hydroxide aqueous solution, and the etching is continued to stop the etching (FIG. 7C). In the case of this example, since the surface roughness of the etching surface up to the boron-doped layer 46 is suppressed to 1/10 or less as compared with the case where the 5w% potassium hydroxide aqueous solution alone is used for etching, the etching surface 72 at the time of etching stop is Surface roughness is less than 0.1 micron. By performing etching using the above two kinds of etching solutions, the thickness accuracy of the diaphragm 5 can be set to 2 ± 0.05 μm, and an inkjet head having excellent ejection stability can be provided.

(Embodiment 3) A state in which the etching step of the third embodiment of the present invention is performed by using an aqueous solution of potassium hydroxide having a concentration of 35% by weight and an aqueous solution of potassium hydroxide having a concentration of 5% by weight, and etching is stopped. The case where additional etching is performed will be described with reference to the first substrate etching process diagram in FIG.

As described in the first embodiment, the Si substrate 41 (FIG. 8A) on which the boron-doped layer 46 is formed and the oxide film 42 is patterned is etched with a 35 w% potassium hydroxide aqueous solution. Is a boron-doped layer 46
Until just before (about 10 microns remaining) (Fig. 8
(B)) The etching is continued and stopped with a 5w% potassium hydroxide aqueous solution (FIG. 8C).
Further, the etching is continued from the etching stopped state, and etching is performed until the thickness of the diaphragm is reached (FIG. 8D). By the above-mentioned etching method, the surface roughness of the etching surface 81 up to the etching stop is suppressed, and the surface roughness is reduced by the additional etching from the etching stop surface 82. The roughness was further reduced, and the diaphragm thickness accuracy could be set to 2 ± 0.025 μm. Further, by further improving the accuracy of the diaphragm thickness, the ejection stability of the inkjet head is further increased.

(Embodiment 4) Regarding the concentration of the low-concentration potassium hydroxide aqueous solution which is the fourth embodiment of the present invention, the etching solution concentration and the etching stop selection ratio (undoped Si to the etching rate of boron-doped Si) The etching rate ratio) of FIG. 9 will be described with reference to FIG.

The point of selecting the concentration of the low-concentration etching solution of the potassium hydroxide aqueous solution is how to obtain a large etching stop selection ratio. That is, it means how much the etching stop can absorb the surface roughness and the variation in the thickness of the Si substrate that occur until the etching stop, and it is desirable that the etching stop selection ratio be high. Considering that the surface roughness of the etching surface up to the boron-doped layer 46 is about 10 μm in the low-concentration etching solution, in order to suppress the diaphragm thickness accuracy within ± 0.3 μm at worst,
A selection ratio of 16 or more is required. That is, in order to secure the selection ratio of 16 or more, it can be seen from FIG. 9 that the concentration of the aqueous potassium hydroxide solution is 10 w% or less. On the other hand, if the concentration of the potassium hydroxide aqueous solution is extremely low, the etching ability for Si tends to be unstable, and if the concentration is lower than 0.5 w%, it is not practical. Therefore, the optimum concentration of the low-concentration potassium hydroxide aqueous solution for the purpose of stopping the etching in forming the vibration plate in the inkjet head manufacturing method is 0.5 to 10 w%, and the low-concentration potassium hydroxide causes surface roughness of the vibration plate. As a result, the inkjet head with stable print quality can be provided. .

(Embodiment 5) The concentration of a high-concentration aqueous potassium hydroxide solution, which is the fifth embodiment of the present invention, will be described with reference to FIG. 10 showing the relationship between the etching amount and the surface roughness.

A major purpose of using a high-concentration potassium hydroxide aqueous solution as an etching solution is to suppress the surface roughness of the etching surface until just before reaching the boron-doped layer 46. In selecting the concentration, only the surface roughness generated by etching is used. You should pay attention to. From FIG. 10, it can be seen that the roughness of the etching surface with the low concentration etching solution is about 10 μm in the state of 170 μm etching just before reaching the boron-doped layer 46. Roughness of 10 μm generated in low-concentration potassium hydroxide aqueous solution is 3 with etching solution of 30 w% or more.
Since the surface roughness is suppressed to a micron or less, the surface roughness when etching is performed up to the etching stop with low-concentration potassium hydroxide can be suppressed to a maximum of 0.2 micron. Therefore, in order to reduce the surface roughness of the diaphragm, it is understood that the concentration of the potassium hydroxide aqueous solution should be increased, but the maximum adjustable concentration of the potassium hydroxide aqueous solution is 55 w%.
Therefore, in order to form a diaphragm having a thickness accuracy required to realize an inkjet head having excellent printing performance, the optimum concentration of the high-concentration potassium hydroxide aqueous solution used in the initial etching step is 30 to 5
Must be 5 w%.

[0037]

EFFECTS OF THE INVENTION In forming a vibration plate of an ink jet head, when etching is performed only with a low-concentration potassium hydroxide aqueous solution, surface roughness of the vibration plate remaining at the time of etching stop is improved by performing additional etching from the etching stop state. As a result, the thickness accuracy of the diaphragm was improved, and an inkjet head with stable ink ejection performance could be provided. In addition, it was possible to improve the thickness accuracy of the diaphragm by improving the surface roughness of the diaphragm by initial etching using a high-concentration potassium hydroxide aqueous solution to suppress surface roughness and by continuing etching stop with a low-concentration potassium hydroxide aqueous solution. It is possible to improve the quality of the inkjet head, and an inkjet head having excellent printing quality is obtained.

Furthermore, initial etching with a high-concentration potassium hydroxide aqueous solution and etching stop with a low-concentration potassium hydroxide aqueous solution are performed to form a vibration plate, and then the vibration plate is further additionally etched with a low-concentration potassium hydroxide aqueous solution. By doing so, it is possible to suppress the surface roughness of the diaphragm to a low level, so that it is possible to further increase the thickness accuracy of the diaphragm, and to provide an inkjet head and an inkjet printer with better printing quality. became.

[Brief description of drawings]

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

FIG. 2 is a sectional side view of the inkjet head according to the first embodiment of the present invention.

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

FIG. 4 is a diffusion process diagram that constitutes a manufacturing process of the first substrate of the inkjet head according to the first embodiment of the present invention.

FIG. 5 is a process drawing of etching that constitutes a manufacturing process of the first substrate of the inkjet head according to the first embodiment of the present invention.

FIG. 6 is a relationship diagram between a boron concentration and an etching rate in the first embodiment of the present invention.

FIG. 7 is a process drawing of etching that constitutes a manufacturing process of a first substrate of an inkjet head according to a second embodiment of the present invention.

FIG. 8 is an etching process diagram that constitutes a manufacturing process of a first substrate of an inkjet head according to a second embodiment of the present invention.

FIG. 9 is a diagram showing the relationship between potassium hydroxide concentration and selectivity in the fourth example of the present invention.

FIG. 10 is a relationship diagram between the etching amount and the surface roughness in the fifth embodiment of the present invention.

[Explanation of symbols]

 1 First Substrate 2 Second Substrate 3 Third Substrate 5 Vibrating Plate 6 Discharge Chamber 7 Recess 8 Recess 8 Orifice 9 Fine Groove 10 Ink Cavity 11 Recess 12 Oxide Film 13 Electrode 14 Recess 15 Lead 16 Terminal 17 Nozzle 18 Ink supply port 19 Transmitting circuit 20 Ink droplet 21 Recording paper 41 Substrate 42 Oxide film 43 Surface on which boron dope layer is formed 44 Opposite surface 45 Diffusing agent 46 Boron dope layer 47 Boron compound 48 Oxide film 51 Exposed portion 52, 53 Etched surface 54 Etching surface 71,72 Etching surface 81,83 Etching surface 82 Etching stop surface G Gap

Claims (7)

[Claims] 1. A single or a plurality of nozzle holes for ejecting ink droplets, a discharge chamber connected to each of the nozzle holes, a vibration plate constituting at least one wall of the discharge chamber, and the vibration plate. And a drive unit that causes deformation, the drive unit including an electrode that deforms the diaphragm by an electrostatic force,
In the method of manufacturing an inkjet head, wherein the diaphragm is a Si substrate including a high-concentration p-type impurity layer, etching is performed with a low-concentration potassium hydroxide aqueous solution from a surface of the Si substrate opposite to a surface on which the high-concentration p-type impurity layer is formed. The high concentration p
A method for manufacturing an ink jet head, characterized in that a diaphragm is formed by leaving the mold impurity layer left, and the remaining diaphragm is etched by the low-concentration potassium hydroxide aqueous solution. 2. A single or a plurality of nozzle holes for ejecting ink droplets, a discharge chamber connected to each of the nozzle holes, a vibration plate forming at least one wall of the discharge chamber, and the vibration plate. And a drive unit that causes deformation, the drive unit including an electrode that deforms the diaphragm by an electrostatic force,
In the method of manufacturing an inkjet head, wherein the diaphragm is a Si substrate made of a high-concentration p-type impurity layer, the high-concentration p-type impurity layer opposite to the surface of the Si substrate on which the high-concentration p-type impurity layer is formed. The etching of the Si substrate up to the vicinity of the high concentration potassium hydroxide aqueous solution is performed, and the etching from the vicinity of the high concentration p type impurity layer to the high concentration p type impurity layer is performed using the low concentration potassium hydroxide aqueous solution. A method of manufacturing an inkjet head, characterized in that a vibration plate is formed by leaving a concentration p-type impurity layer. 3. The manufacturing of an ink jet head according to claim 2, wherein the diaphragm formed using the high-concentration potassium hydroxide and the low-concentration potassium hydroxide is etched with a low-concentration potassium hydroxide aqueous solution. Method. 4. The low-concentration aqueous potassium hydroxide solution has a concentration of 0.5 to 10 w%.
4. The method for manufacturing an inkjet head according to any one of 3 to 3. 5. The method for manufacturing an inkjet head according to claim 2, wherein the concentration of the high-concentration potassium hydroxide aqueous solution is 30 to 55% by weight. 6. The method of manufacturing an inkjet head according to claim 1, wherein the high-concentration p-type impurity layer is a high-concentration boron-doped layer. 7. An inkjet printer having an inkjet head obtained by the manufacturing method according to claim 1.