JP2002036541A - Liquid jet head and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jet head wherein a diaphragm can be driven by a low voltage and the durability is improved. SOLUTION: The diaphragm is formed of a silicon layer having a high concentration P type impurity and the peak concentration of the P type impurity is set in the inner section of the diaphragm in the depth direction of the diaphragm. It is preferable that the diaphragm has a concentration inclination of the P type impurity that becomes lower as it goes toward the liquid chamber and a concentration inclination thereof that becomes lower as it goes toward the opposite the liquid chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet discharge head and a method of manufacturing the same.

[0002]

2. Description of the Related Art An ink jet head, which is a liquid drop discharge head used in an image recording apparatus such as a printer, a facsimile, a copying apparatus, or the like, is used as an ink jet recording apparatus. A pressure chamber including a communicating liquid chamber (also referred to as a pressurized liquid chamber, a pressure chamber, a discharge chamber, an ink flow path, etc.) and pressure generating means for generating pressure for pressurizing the ink in the liquid chamber; The ink droplets are ejected from the nozzles by pressurizing the liquid chamber ink with the pressure generated in step (1).

A conventional ink jet head is of a piezo type which discharges ink droplets by deforming and displacing a diaphragm forming a wall surface of a liquid chamber by using a piezoelectric element, and a heating resistor disposed in the liquid chamber. Bubble type that generates bubbles by ink film boiling using a body and ejects ink droplets, and vibrates with electrostatic force using a vibrating plate (or an electrode integrated therewith) that forms the wall surface of the liquid chamber and electrodes There is an electrostatic type in which ink droplets are ejected by deforming and displacing a plate.

In an ink jet head using a diaphragm such as the piezo type or the electrostatic type described above, the mechanical displacement characteristics of the diaphragm greatly affect the ink picking and discharging characteristics. Is required.

Therefore, in the conventional ink jet head, Japanese Patent Application Laid-Open Nos. Hei 6-23986 and Hei 6-71
As described in Japanese Patent Application Laid-Open No. 882 or Japanese Patent Application Laid-Open No. 9-267479, a high-concentration boron diffusion layer in which boron is diffused is formed on a silicon substrate forming a diaphragm, and this silicon substrate is anisotropically etched. As a result, the etching is stopped at the high concentration boron diffusion layer,
A diaphragm made of a high-concentration boron diffusion layer is formed.

As described above, as a method of forming a high-concentration boron layer serving as a diaphragm on a silicon substrate, a solid diffusion method using a plate-like diffusion source (BN or B ₂ O ₃ ), or a method of diffusing Br ₃ is used. There are known a gas phase diffusion method, an ion implantation method in which boron is implanted with high energy, and a coating diffusion method in which B ₂ O ₃ is dispersed in an organic solvent and spin-coated on a wafer.

[0007]

However, in the above-described solid diffusion method, vapor phase diffusion method and coating diffusion method, boron is diffused from the surface of the silicon substrate (the surface facing the electrode surface). Therefore, when the diaphragm is formed, a high-concentration region (peak concentration region) is likely to be generated on the surface opposite to the liquid chamber in the thickness direction of the diaphragm. In addition, even in the ion implantation method, the thickness of the diaphragm and the space on the apparatus are limited, and similarly, a peak concentration region is likely to be formed on the surface opposite to the liquid chamber.

In the case of a boron-doped layer, the higher the boron concentration, the higher the tensile stress. Therefore, if the peak concentration region is located on the surface opposite to the liquid chamber as described above, the vibration plate will A force to warp convexly acts on the liquid chamber side.

As described above, in the conventional ink jet head, since the diaphragm is subjected to the tensile stress acting in the direction of warping toward the liquid chamber, the driving voltage for displacing the diaphragm toward the electrode by a predetermined amount is applied. In addition, there is a problem that the durability (repeated vibration characteristics) of the diaphragm is lowered because the diaphragm is deformed against the stress.

The present invention has been made in view of the above problems, and has as its object to provide a droplet discharge head with improved durability by improving the durability of a diaphragm.

[0011]

In order to solve the above-mentioned problems, in the droplet discharge head according to the present invention, the diaphragm is made of a high-concentration P-type impurity silicon layer, and the diaphragm is arranged in the thickness direction of the diaphragm. The structure has a peak concentration of a P-type impurity therein.

Here, the diaphragm is arranged in the thickness direction of the diaphragm.
It is preferable to have a concentration gradient of the P-type impurity that decreases in the liquid chamber direction and in the direction opposite to the liquid chamber. Further, it is preferable that the P-type impurity concentration on the surface of the diaphragm opposite to the liquid chamber does not exceed 1 * 10 ²⁰ (atom / cm ³ ).

Further, the difference between the concentration of the P-type impurity on the surface of the vibration plate on the liquid chamber side and the concentration of the P-type impurity on the surface on the side opposite to the liquid chamber may not exceed 1 * 10 ²⁰ (atom / cm ³ ). preferable. In this case, it is more preferable that the difference between the concentration of the P-type impurity on the surface of the vibration plate on the liquid chamber side and the concentration of the P-type impurity on the surface on the side opposite to the liquid chamber does not exceed 3 * 10 ¹⁹ (atom / cm ³ ). . Furthermore, high-concentration boron can be used as the high-concentration P-type impurity. Further, it is preferable that the droplet discharge head has an electrode facing the diaphragm and discharges the droplet by deforming and displacing the diaphragm with electrostatic force.

A method for manufacturing a droplet discharge head according to the present invention is a method for manufacturing a droplet discharge head according to the present invention,
After the boron is diffused into the silicon substrate, the surface of the boron diffusion layer is oxidized. Here, it is preferable that after the boron is diffused into the silicon substrate, the surface of the boron diffusion layer is polished, and then the surface of the boron diffusion layer is oxidized.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of an electrostatic ink jet head to which the present invention is applied, FIG. 2 is a top view illustrating the head in a transparent state, and FIG. 3 is a schematic cross-sectional view of the same head along a long side of a liquid chamber. FIG. 4 is a schematic cross-sectional explanatory view along the liquid chamber short side direction of the head.

This ink jet head includes a diaphragm / liquid chamber substrate 1 as a first substrate, an electrode substrate 3 as a second substrate provided below the diaphragm / liquid chamber substrate 1, and a diaphragm / liquid chamber. It is a laminated structure in which a nozzle plate 4 which is a third substrate provided on the upper side of the substrate 1 is overlapped and joined, whereby a plurality of nozzles 5, a liquid chamber 6 which is an ink flow path communicating with each nozzle 5, A common ink chamber 8 and the like communicating with the liquid chamber 6 via a fluid resistance portion 7 are formed.

The vibration plate / liquid chamber substrate 1 includes a liquid chamber 6, a vibration plate 10 forming a bottom wall of the liquid chamber 6, a recess forming a partition 11 separating each liquid chamber 6, and a common ink chamber 8. Are formed. The diaphragm / liquid chamber substrate 1 diffuses boron, which is a high-concentration impurity, to a thickness (depth) serving as a diaphragm on a silicon substrate, and performs anisotropic etching using the high-concentration boron-doped layer as an etching stop layer. Thus, a diaphragm 5 having a desired thickness is obtained when forming a concave portion or the like that becomes the liquid chamber 6 by the method described above. Note that gallium, aluminum, or the like can be used as the high-concentration P-type impurity in addition to boron.

An insulating film of 0.1 μm SiO ₂ or the like is formed on the entire surface of the vibration plate / liquid chamber substrate 1 by thermal oxidation in order to prevent dielectric breakdown and short circuit during ink jet driving. .

A concave portion 14 is formed in the electrode substrate 3, and a counter electrode 15 is formed on the bottom surface of the concave portion 14 with a predetermined gap 16 in the diaphragm 10. An actuator unit that changes the internal volume of the liquid chamber 6 by displacing the diaphragm 15 is configured. To prevent the electrode 15 from being damaged by contact with the diaphragm 10 on the electrode 15 of the electrode substrate 3, for example, 0.1
An insulating layer 17 such as SiO _{2 having a} thickness of μm is formed. The electrode 15 extends to near the end of the electrode substrate 3 to form an electrode pad portion 15a for connecting to an external drive circuit via a connection means.

The electrode substrate 3 has a concave portion 14 formed on a glass substrate or a Si substrate having a thermal oxide film 3a formed on the surface thereof by etching with an HF aqueous solution or the like.
An electrode material having high heat resistance such as titanium nitride is formed to a desired thickness by a film forming technique such as sputtering, CVD, or vapor deposition, and then a photoresist is formed and etched, so that only the concave portion 14 is formed. The electrode 15 is formed. The electrode substrate 3 and the diaphragm / liquid chamber substrate 1 are joined by processes such as anodic joining and direct joining.

Here, the electrode 15 is formed by sputtering titanium nitride to a thickness of 0.1 μm in a recess 14 having a depth of 0.3 μm formed by etching a silicon substrate.
Therefore, in this head, the length of the gap 16 after the electrode substrate 3 and the diaphragm / liquid chamber substrate 1 are joined (the distance between the diaphragm 10 and the electrode 15) is 0.2 μm.

The nozzle plate 4 is made of stainless steel (SUS) having a thickness of 50 μm.
And an ink supply port 19 for supplying ink from outside to the common ink liquid chamber.

Next, a first embodiment of the manufacturing process of the ink jet head according to the present invention will be described with reference to FIGS. First, using a 500 μm-thick Si substrate 20 having a crystal plane orientation (110) as shown in FIG. 5A, boron is diffused into the surface of the Si substrate 20 by a solid state diffusion method. A high-concentration boron diffusion layer 21a is formed as shown in FIG.

More specifically, the Si substrate 20 and a solid diffusion source (BN or B ₂ O ₃ ) are set in a furnace at a temperature of 750 ° C. so as to face each other. In this furnace, 0.25% of oxygen is mixed and nitrogen is allowed to flow. Then, the temperature of the furnace is raised to a temperature of 1150 ° C. at a rate of 7 ° C./min, and the state is maintained for 50 minutes, and then lowered to a temperature of 750 ° C. at a rate of 7 ° C./min. As shown in (b), a high-concentration boron diffusion layer 21 is formed.

In addition, a vapor phase diffusion method using BBr ₃ , an ion implantation method in which boron is implanted with high energy, or a coating diffusion method in which B ₂ O ₃ is dispersed in an organic solvent and spin-coated on a wafer is also used. The concentration boron diffusion layer 21a can be formed.

Thereafter, the B formed on the surface of the Si substrate 20 is
By removing the ₂ O ₃ layer with hydrofluoric acid, a high-concentration boron-doped layer is formed.

The high-concentration boron-doped layer 21a (range of 2 μm in the thickness direction from the surface of the Si substrate 20) obtained at this stage has a surface (surface opposite to the liquid chamber side) as shown by a short broken line a in FIG. ) Has the highest concentration distribution.

Then, the surface of the Si substrate 20 is oxidized to form an oxide film 22 as shown in FIG. Here, the oxidation conditions were O ₂ gas 6 sccm, H ₂
Gas: 9 sccm, 900 ° C for 60 minutes, approx.
An oxide film 22 having a thickness of 5 mm was formed. Thereafter, as shown in FIG. 3D, the oxide film 22 formed on the surface of the Si substrate 20 was removed with hydrofluoric acid to form a surface layer of the Si substrate.

At this time, the oxide film 22 is removed from the surface of the Si substrate 20.
7, the high-concentration boron diffusion layer 21 forming the surface of the Si substrate 20 has a high-concentration boron concentration inside the diaphragm in the thickness direction of the diaphragm, as indicated by the solid line b in FIG. Distribution.

After that, it is rough due to the diffusion of boron.
To enable direct bonding of the surface of the Si substrate 20, C
A high-concentration boron diffusion layer 21 having a surface roughness Ra = 0.5 nm or less was obtained by MP (chemical-mechanical-polishing). In this CMP, since the outermost layer of the Si substrate 20 can be uniformly polished in a plane with a polishing amount of 1000 ° or less, the change of the high-concentration boron diffusion layer 21 is very small. In this case, diffusion conditions for diffusing boron and oxidation conditions for oxidizing the surface of the Si substrate 20 may be determined in consideration of the polishing amount.

Next, the silicon substrate 20 obtained as described above is directly bonded onto the separately manufactured electrode substrate 3 as shown in FIG. Here, the pre-bonded material under reduced pressure was subjected to a heat treatment at a temperature of 900 ° C. for one hour to be joined.

Then, as shown in FIG.
The upper surface of the 00 μm Si substrate 40 was polished to a thickness of 1 μm.
After that, the silicon nitride film 24 is formed on the entire surface of the bonded electrode substrate 3 and Si substrate 20 by LP-CVD as shown in FIG.

Next, a resist is coated on the silicon nitride film 24 formed on the Si substrate 20 and exposed,
By performing the phenomenon, a resist pattern corresponding to the liquid chamber 6 and the common ink chamber 8 is formed. At this time, alignment is performed by IR light so that the electrode 15 of the electrode substrate 3 and the resist pattern of the liquid chamber 6 match. Next, the Si substrate 20
The upper silicon nitride film 24 is removed by dry etching,
By removing the resist, a pattern 25 of the silicon nitride film 24 is formed as shown in FIG.

When the Si substrate 20 is etched by immersion in a KOH (10 wt%) aqueous solution, the etching proceeds from the opening on the patterned side, and when the boron concentration reaches a depth of 1E20 / cm ³ , the etching is performed. Is stopped (the etch rate becomes extremely low), and as shown in FIG. 3E, a concave portion serving as the liquid chamber 6 and a diaphragm 10 made of high-concentration boron-doped silicon (high-concentration boron diffusion layer 21) are formed. . By joining the nozzle plate 4 to this, the above-described ink jet head is obtained.

As described above, the vibration plate 10 in this ink jet head is the same as that shown in FIG.
Has a peak concentration inside the diaphragm as shown by a solid line b,
There is a concentration gradient of high-concentration boron that becomes lower in concentration toward the liquid chamber 6 and the electrode 15 side opposite to the liquid chamber 6.

Accordingly, the tensile stress caused by the high-concentration boron acting on the diaphragm 10 becomes strongest inside the diaphragm 10, so that the force for warping the diaphragm 10 to the liquid chamber 6 side in a convex shape is reduced. The driving voltage required for deforming and displacing the diaphragm 10 toward the electrode 15 is reduced, so that low-voltage driving becomes possible, and the durability (repeated vibration characteristics) is also improved.

Then, an evaluation test was performed on the high-concentration boron concentration (unit: atom / cm ³ ) and durability on the surface of the diaphragm 10 on the electrode 15 side. Example 1 A diaphragm having an electrode-side surface concentration of 1.00E + 20 as shown by a solid line b in FIG. 8 was manufactured by anisotropic etching using a KOH aqueous solution and using the above-described manufacturing method. Note that FIG. 9 shows the concentration profile in the thickness direction of the diaphragm 10 with the surface of the diaphragm 10 on the electrode 15 side being “0 μm” as shown in FIG. 9 (the same applies to FIG. 7 described above). .

Example 2 In the same manner as in Example 1, a diaphragm having an electrode-side surface concentration of 1E18 was manufactured as shown by a dashed line c in FIG. Example 3 In the same manner as in Example 1, a diaphragm having an electrode-side surface concentration of 1.00E + 19 was produced as shown by a two-dot chain line d in FIG.

Comparative Example 1: A diaphragm having a peak concentration on the electrode side surface as shown by a short broken line a in FIG.

Then, the inkjet head having each of the diaphragms of Examples 1 to 3 and Comparative Example 1 was driven at a drive frequency of 10 kHz, and the number of times of driving at which characteristic deterioration occurred was measured. Properties) were evaluated. This result is shown in FIG.

As can be seen from FIG.
While the characteristic degradation occurred at 0 * 10 ⁹ times or less, in the case of the first embodiment, 1.0 * 10 ⁹ times or more to 5.0 * 10 ⁹ times, and in the case of the second embodiment, 1.0 * 10 ⁹ times. ^{In the} case of Example 3, the characteristics did not deteriorate even with the number of driving times of 5.0 * 10 ⁹ times or more and 1.0 * 10 ¹⁰ times.

Therefore, by setting the concentration of high-concentration boron on the surface of the electrode 15 to a concentration not exceeding 1 * 10 ²⁰ , the stress of the diaphragm 10 can be further reduced, and low-voltage driving and durability can be achieved. Can be improved. More preferably, electrode 1
The durability can be further improved by making the concentration not exceeding the high-concentration boron concentration of 8 * 10 ¹⁹ on the 5-side surface.

Next, an evaluation test was conducted on the relationship between the concentration of high-concentration boron on the surface of the vibration plate 10 on the liquid chamber 6 side and the concentration of high-concentration boron on the surface of the electrode 15 side. Example 4: EDP (ethylenediamine pyrocatechol)
A diaphragm having a surface concentration on the liquid chamber side higher than that on the electrode side by 1E20 or more as shown by a solid line b in FIG. 11 was manufactured by anisotropic etching using an aqueous solution and using the above-described manufacturing method.

Example 5 In the same manner as in Example 4, a diaphragm having a surface concentration on the liquid chamber side approximately 3E19 higher than the surface concentration on the electrode side was manufactured as shown by a long broken line c in FIG. Example 6 In the same manner as in Example 4, a diaphragm having substantially the same liquid chamber-side surface concentration and electrode-side surface concentration as shown by the dashed line d in FIG.

Example 7: In the same manner as in Example 4, a diaphragm having an electrode-side surface concentration lower by approximately 3E19 than a liquid-chamber-side surface concentration as shown by a two-dot chain line e in FIG. Example 8: In the same manner as in Example 4, FIG.
As shown in the figure, a diaphragm having the electrode-side surface concentration lower by about 1E20 than the liquid-chamber-side surface concentration was manufactured.

Comparative Example 2: Anisotropic etching using an aqueous solution of EDP (ethylenediamine pyrocatechol)
A diaphragm having a peak concentration on the electrode side surface as shown by a short broken line a in FIG.

Then, the inkjet head having each of the diaphragms of Examples 4 to 8 and Comparative Example 2 was driven at a driving frequency of 10 kHz, and the number of times of driving at which characteristic deterioration occurred was measured. Properties) were evaluated. This result is shown in FIG.

As can be seen from FIG.
0 * 10⁹In contrast to the example in
1.0 * 10 for 4⁹More than 5.0 * 10⁹Turn
In Examples 5 to 7, 1.0 * 10^TenMore than once, real
5.0 * 10 in Example 8 ⁹1.0 * 10^TenTimes
No characteristic degradation occurred even with the number of driving times up to.

Accordingly, the difference between the concentration of high-concentration boron on the surface of the diaphragm 10 on the liquid chamber 6 side and the concentration of high-concentration boron on the surface of the electrode 15 does not exceed 1 * 10 ^20, thereby improving durability. The durability is further improved by preventing the difference in density from exceeding 3 * 10 ¹⁹ .

Next, a process of forming a high-concentration boron diffusion layer in a second embodiment of the method for manufacturing an ink jet head according to the present invention will be described with reference to FIG. In this embodiment, as shown in FIGS. 5A and 5B, the high-concentration boron diffusion layer 21a is formed on the surface of the silicon substrate 20 in the same process as that described in FIGS. 5A and 5B. Is formed, the surface of the high-concentration boron diffusion layer 21a is polished by CMP as shown in FIG.

Thereafter, by oxidizing the surface of the Si substrate 20, an oxide film 25 including the surface of the high-concentration boron diffusion layer 21 is formed on the surface of the silicon substrate 20 as shown in FIG. Thereafter, an ink jet head can be manufactured through the same steps as those described with reference to FIG.

[0052] That is, B ₂ O ₃ layer is formed by diffusing high-concentration boron into the silicon substrate 20, Part B ₂
A boron and silicon compound layer is formed below the O ₃ layer. Therefore, as shown in FIG. 5C, the surface of the oxide film 22 obtained by oxidizing this compound layer is rough,
Direct bonding with the liquid chamber substrate 1 is difficult, and since the oxide film 22 contains B ₂ O ₃ , it has a low withstand voltage and cannot be used as an insulating film.
After the removal, polishing is performed so that direct bonding can be performed.

On the other hand, in this embodiment, first,
Since the boron and silicon compound layer is removed by polishing by CMP, it is possible to obtain a silicon surface (the surface of the high-concentration boron diffusion layer 21) having a surface property capable of directly bonding. Since the surface of the oxide film 26 obtained by oxidizing the silicon surface has a surface roughness Ra of 0.5 nm or less, the oxide film 26 can be directly bonded to the electrode substrate with the oxide film 26 remaining. . Moreover, this oxide film 26 is made of B
_Since the content of ₂ O ₃ is small, the withstand voltage is high, and the electric charge is suppressed from remaining on the electrode, the durability can be improved and stable driving can be performed.

In each of the embodiments described above, the present invention is applied to an electrostatic ink jet head. However, the present invention can also be applied to a piezo ink jet head. In addition, the present invention can be similarly applied to, for example, a droplet discharge head for discharging a liquid resist.

[0055]

As described above, according to the liquid droplet ejection head of the present invention, the diaphragm has a peak impurity concentration in the diaphragm in the thickness direction of the diaphragm composed of the high-concentration P-type impurity silicon layer. Accordingly, the stress of the diaphragm can be reduced, and low-voltage driving and improvement in durability (repeated vibration characteristics) can be achieved.

Here, in the thickness direction of the diaphragm, there are concentration gradients in which the concentration becomes lower in the liquid chamber direction and in the direction opposite to the liquid chamber, so that the stress of the diaphragm can be reduced. Low voltage driving and improved durability can be achieved.

By controlling the P-type impurity concentration on the surface of the diaphragm opposite to the liquid chamber not to exceed 1 * 10 ²⁰ (atom / cm ³ ), the stress of the diaphragm can be more reliably suppressed. In addition, it is possible to further improve the durability by driving at a lower voltage.

Further, the difference between the P-type impurity concentration on the surface of the diaphragm on the liquid chamber side and the P-type impurity concentration on the surface on the side opposite to the liquid chamber is 1
By not exceeding * 10 ²⁰ (atom / cm ³ ), the durability can be further improved. In this case, the difference between the concentration of P-type impurities (high-concentration boron) on the surface of the diaphragm on the liquid chamber side and the concentration of P-type impurities on the surface on the side opposite to the liquid chamber is 3 * 10.
^By not exceeding ¹⁹ (atom / cm ³ ), the durability can be further improved.

This head has an electrode facing the diaphragm, and the diaphragm is deformed and displaced by electrostatic force to discharge droplets, thereby providing a highly reliable and excellent electrostatic droplet discharge. You can get a head.

According to the method of manufacturing a droplet discharge head according to the present invention, the surface of the boron diffusion layer is oxidized after diffusing boron into the silicon substrate, so that the droplet discharge head according to the present invention can be easily obtained. Can be. In this case, after the boron is diffused into the silicon substrate, the surface of the boron diffusion layer is polished, and then the surface of the boron diffusion layer is oxidized, thereby improving reliability and stably driving by reducing residual charges. A possible droplet discharge head can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electrostatic inkjet head to which the present invention is applied.

FIG. 2 is an explanatory top view showing the transmission state of the head.

FIG. 3 is a schematic cross-sectional explanatory view along a long side direction of a liquid chamber of the head.

FIG. 4 is a schematic cross-sectional explanatory view of the head along a liquid chamber short side direction.

FIG. 5 is an explanatory view illustrating a step of forming a high-concentration boron diffusion layer in a first embodiment of a method for manufacturing an ink jet head to which the present invention is applied.

FIG. 6 is an explanatory view illustrating a manufacturing process of the head according to the first embodiment.

FIG. 7 is a diagram showing the concentration distribution of the high-concentration boron diffusion layer in the stages shown in FIGS. 5 (b) and 5 (e).

FIG. 8 is a graph showing the concentration distribution of high-concentration boron on the electrode-side surface of the diaphragm and a concentration distribution chart for explaining an evaluation test of durability;

FIG. 9 is an explanatory diagram for explaining a density distribution diagram.

FIG. 10 is an explanatory diagram for explaining a result of a durability evaluation test of the diaphragm having each concentration distribution of FIG. 8;

FIG. 11 is a diagram illustrating a difference between the concentration on the liquid chamber side surface of the vibration plate and the concentration on the electrode side surface, and a concentration distribution diagram for explaining a durability evaluation test.

FIG. 12 is an explanatory diagram for explaining a result of a durability evaluation test of the diaphragm having each concentration distribution of FIG. 11;

FIG. 13 is an explanatory view illustrating a process of forming a high-concentration boron diffusion layer in a second embodiment of the method of manufacturing an ink jet head to which the present invention is applied.

[Explanation of symbols]

1: diaphragm / liquid chamber substrate, 3: electrode substrate, 4: nozzle plate,
5 nozzle, 6 liquid chamber, 10 diaphragm, 15 electrode, 2
0: Si substrate, 21: high concentration boron diffusion layer, 22, 26
... an oxide film, 23 ... a silicon nitride film.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Taro Kihata 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C057 AF65 AG12 AG54 AG55 AP02 AP11 AP22 AP56 AP58 BA04 BA15 5D107 AA09 BB20 CC01 CC10

Claims (9)

[Claims] A nozzle for discharging a droplet, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
In a droplet discharge head that discharges droplets from the nozzles by displacing and deforming the vibration plate, the vibration plate is formed of a high-concentration P-type impurity silicon layer, and is placed inside the vibration plate in the thickness direction of the vibration plate. A droplet discharge head having a peak concentration of the P-type impurity. 2. The droplet discharge head according to claim 1, wherein the vibration plate has a low concentration in a liquid chamber direction and in a direction opposite to the liquid chamber in a thickness direction of the vibration plate. An ink jet head having a P-type impurity concentration gradient. 3. The droplet discharge head according to claim 1, wherein the P-type impurity concentration on the surface of the diaphragm opposite to the liquid chamber does not exceed 1 * 10 ²⁰ (atom / cm ³ ). Characteristic inkjet head. 4. The droplet discharge head according to claim 1, wherein said P on the liquid chamber side surface of said vibrating plate.
A droplet discharge head, wherein a difference between the concentration of the type impurity and the concentration of the P-type impurity on the surface opposite to the liquid chamber does not exceed 1 * 10 ²⁰ (atom / cm ³ ). 5. The droplet discharge head according to claim 4, wherein the difference between the concentration of the P-type impurity on the surface of the vibration plate on the liquid chamber side and the concentration of the P-type impurity on the surface on the side opposite to the liquid chamber is three. * 1
0 ¹⁹ (atom / cm ³ ). 6. The droplet discharge head according to claim 1, wherein the high-concentration P-type impurity is high-concentration boron. 7. The droplet discharge head according to claim 1, further comprising an electrode facing the diaphragm, wherein the diaphragm is deformed and displaced by electrostatic force to discharge the droplet. A droplet discharge head characterized in that: 8. The method for manufacturing a droplet discharge head according to claim 1, wherein the surface of the boron diffusion layer is oxidized after boron is diffused into the silicon substrate. A method for manufacturing a droplet discharge head. 9. The method of manufacturing a droplet discharge head according to claim 8, wherein after the boron is diffused into the silicon substrate, the surface of the boron diffusion layer is polished, and then the surface of the boron diffusion layer is oxidized. A method for manufacturing a droplet discharge head, comprising: