JP2002096480A - Liquid drop discharge head and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly join a flow channel substrate and an electrode substrate with high-reliability. SOLUTION: Both the flow channel substrate 1 equipped with a diaphragm 10 and the electrode substrate 3 equipped with an electrode 15 consist of a silicon substrate. An insulating film 20 is formed by grinding an electrode side surface of the diaphragm 10 of the flow channel substrate 1. The flow channel substrate 1 and the electrode substrate 3 are directly joined.

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 for manufacturing the same, and more particularly to an electrostatic droplet discharge head and a method for manufacturing the same.

[0002]

2. Description of the Related Art An ink jet head, which is a droplet discharge head used in an image recording apparatus such as a printer, a facsimile, a copying apparatus, a plotter or the like, or an ink jet recording apparatus used as an image forming apparatus, comprises a nozzle for discharging ink droplets, Liquid chamber with which the nozzle communicates (also referred to as a pressurized liquid chamber, a pressure chamber, a discharge chamber, an ink flow path, etc.)
A diaphragm forming a wall surface of the liquid chamber, and an electrode opposed to the diaphragm, wherein the diaphragm is deformed and displaced by electrostatic force to pressurize the liquid chamber ink to discharge ink droplets from the nozzles. There is an electric inkjet head.

In such an electrostatic ink jet head, the mechanical displacement characteristics of the vibration plate greatly affect the ink picking and discharging characteristics. Must be secured with high precision.

Therefore, in the conventional electrostatic ink jet head, Japanese Patent Application Laid-Open Nos. Hei 6-23986 and Hei 6
As described in JP-A-7-18882 or JP-A-9-267479, a high-concentration boron diffusion layer in which boron is diffused is formed on a silicon substrate on which a diaphragm is formed, and this silicon substrate is anisotropically etched. As a result, since the etching is stopped at the high-concentration boron diffusion layer, a diaphragm made of the high-concentration boron diffusion layer is formed, and the silicon substrate provided with the diaphragm and the silicon substrate provided with the electrodes are directly bonded. I have.

Further, as described in JP-A-6-71882, after an oxide film is formed on a silicon substrate, a portion corresponding to the shape of the diaphragm is opened by photolithography and etching techniques. There is also an ink jet head in which high-concentration boron is doped only in a portion so that boron is not diffused to a bonding surface with a silicon substrate provided with an electrode. Further, JP-A-10-44
As described in Japanese Patent Publication No. 406, SOI (Silicon
There is also an ink jet head that forms a diaphragm using an oxide film (insulator) as an etching stop layer using a substrate on an insulator.

[0006]

By the way, the bonding surface in the direct bonding is required to have an extremely good surface property.
As described above, when the vibration plate is formed of the high-concentration boron diffusion layer, direct bonding is performed via the high-concentration boron diffusion surface, so that highly reliable bonding is difficult.

That is, a high-concentration boron etch stop layer is formed by a solid diffusion method using a plate-like diffusion source (BN or B ₂ O ₃ ), a gas phase diffusion method using BBr ₃ , an ion implantation method, or the like. There is a coating diffusion method in which B ₂ O ₃ is dispersed in an organic solvent and spin-coated on a wafer, but a glass layer (a buffer before ion implantation in the case of ion implantation) An oxide film, etc.), and an alloy (Si) between the glass layer and the silicon layer.
_B4-6 ) A layer is formed. The glass layer can be removed with a hydrofluoric acid aqueous solution, but the alloy layer cannot be removed. This alloy layer is hydrophilic and has a large surface roughness, which hinders direct bonding. Although the alloy layer can be removed by etching with a hydrofluoric / nitric acid solution or the like, the reliability of bonding is reduced because the surface roughness of the boron diffusion surface after the removal of the alloy layer is large.

Further, the surface of the deposition surface formed by the CVD method, the sputtering method or the like often has a surface roughness of a level which is difficult to obtain a reliable and strong bonding force by the direct bonding method. It is difficult to directly join these surfaces as a joining surface, and it is not possible to perform highly reliable direct joining.

Further, after an oxide film is formed on the silicon substrate as described above, a portion corresponding to the shape of the diaphragm is opened by photolithography and etching techniques, and only the opening is doped with boron to form boron on the junction. Although it is possible to prevent diffusion, this leads to an increase in process cost due to an increase in the number of steps, and extra dimensions such as an alignment margin at the time of joining must be taken, which hinders high density.

The present invention has been made in view of the above problems, and has as its object to provide a droplet discharge head capable of obtaining high density and high reliability and a method of manufacturing the same.

[0011]

According to a first aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate. Process, the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate and the silicon layer.
A step of polishing and removing the boron alloy layer, a step of directly bonding the high-concentration P-type impurity diffusion layer of the first silicon substrate and the second silicon substrate provided with the electrodes by direct bonding, and a step of bonding the second silicon substrate. Forming a diaphragm by performing anisotropic alkali etching of the combined first silicon substrate.

According to a second aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; Removing the glass layer formed on the surface of the diffusion layer by wet etching, polishing and removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate; A step of directly bonding a high-concentration P-type impurity diffusion layer of the substrate and a second silicon substrate provided with electrodes by direct bonding, and an alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate. And forming a vibration plate.

According to a third aspect of the invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; Removing the glass layer formed on the surface of the diffusion layer by wet etching, oxidizing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate; Removing the oxide layer of the alloy layer, polishing the high-concentration P-type impurity diffusion surface, and facing the high-concentration P-type impurity diffusion layer of the first silicon substrate with the second silicon substrate provided with the electrodes. It is configured to include a step of bonding by direct bonding, and a step of forming a diaphragm by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate. .

According to a fourth aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate and oxidizing a silicon-boron alloy layer; Removing the glass layer and the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate by wet etching, and polishing the high-concentration P-type impurity diffusion surface; A step of directly bonding the high-concentration P-type impurity diffusion layer of the first silicon substrate and the second silicon substrate provided with the electrodes by direct bonding, and bonding the first silicon substrate bonded to the second silicon substrate with an alkali. And forming a diaphragm by anisotropic etching.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; A step of polishing and removing a part of the glass layer formed on the surface of the diffusion layer, and bonding the high-concentration P-type impurity diffusion layer of the first silicon substrate to the second silicon substrate provided with the electrodes by direct bonding. And a step of forming a vibrating plate by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; Removing the glass layer formed on the surface of the diffusion layer by wet etching; removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer by wet etching; Polishing the surface, bonding the high-concentration P-type impurity diffusion layer of the first silicon substrate to the second silicon substrate provided with the electrodes by direct bonding, and bonding the second silicon substrate. Forming a vibration plate by subjecting the first silicon substrate to alkali anisotropic etching.

According to a seventh aspect of the invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; A step of polishing and removing the glass layer and the silicon-boron alloy layer on the surface of the diffusion layer, a step of forming an insulating film on the surface of the high-concentration P-type impurity diffusion layer, and a second silicon substrate provided with a first silicon substrate and an electrode And a step of forming a diaphragm by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate.

According to a eighth aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; Removing the glass layer on the surface of the diffusion layer by wet etching, polishing and removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate; A step of forming an insulating film on the surface of the diffusion layer, a step of bonding the first silicon substrate and the second silicon substrate provided with the electrodes by direct bonding, and a step of bonding the first silicon substrate bonded to the second silicon substrate with an alkali. And forming a diaphragm by anisotropic etching.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; Removing the glass layer on the surface of the diffusion layer by wet etching, oxidizing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate, and removing the silicon-boron alloy layer. Removing the oxide layer; polishing the high-concentration P-type impurity diffusion surface; forming an insulating film on the surface of the high-concentration P-type impurity diffusion layer; A step of bonding the silicon substrate by direct bonding, and a step of forming a diaphragm by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate. Than it is.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate and oxidizing a silicon-boron alloy layer; Removing the glass layer and the silicon-boron alloy layer on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate by wet etching,
Polishing the high-concentration P-type impurity diffusion surface, forming an insulating film on the surface of the high-concentration P-type impurity diffusion layer, and bonding the first silicon substrate and the second silicon substrate provided with the electrodes by direct bonding It is configured to include a joining step and a step of forming a diaphragm by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate.

According to an eleventh aspect of the present invention, there is provided a method of manufacturing a droplet discharge head, comprising: forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; Removing the glass layer on the surface of the diffusion layer by wet etching, removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer by wet etching, and polishing the high-concentration P-type impurity diffusion surface A step of forming an insulating film on the surface of the high-concentration P-type impurity diffusion layer; and a step of directly bonding the first silicon substrate and the second silicon substrate provided with the electrodes by bonding.
Forming a vibration plate by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate.

In the method of manufacturing a droplet discharge head according to the present invention including the step of forming these insulating films, it is preferable that at least the insulating film at the junction with the second silicon substrate is removed. Preferably, the insulating film is a thermal oxide film. Further, the surface roughness of the insulating film is Ra = 0.
Preferably it does not exceed 5 nm.

In the method of manufacturing a droplet discharge head according to each of the above-mentioned inventions, it is preferable that the high-concentration P-type impurity is high-concentration boron. In the polishing step, it is preferable to perform polishing by a chemical mechanical polishing method using an aqueous solution having a hydroxyl group in the slurry liquid. Alternatively, in the polishing step, polishing is preferably performed by a spin etching method.

In the droplet discharge head according to the present invention, the first substrate provided with the vibrating plate and the second substrate provided with the electrodes are both formed of a silicon substrate, and the first and second substrates are formed by polishing at least one of the substrates. The machined surface is used as a joining surface to directly join.

Here, it is preferable that an insulating film having a polished surface is formed on the surface of the diaphragm facing the electrode.
Further, it is preferable that the diaphragm is formed of a high-concentration P-type impurity silicon layer. Further, it is preferable that the surface roughness of the polished surface does not exceed Ra = 0.5 nm.

The droplet discharge head according to the present invention has a laminated structure in which at least a first substrate provided with a vibration plate and a second substrate provided with electrodes are overlapped and joined, and the first substrate is made of a silicon substrate; It has a polished P-type impurity diffusion layer, and an insulating film formed on the polished surface of the P-type impurity diffusion layer is provided on the surface of the diaphragm facing the electrode.

Here, it is preferable that at least the insulating film at the joint with the second substrate is removed. Preferably, the insulating film is a thermal oxide film. Further, it is preferable that the surface roughness of the insulating film does not exceed Ra = 0.5 nm.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of an electrostatic inkjet head as a droplet discharge head according to the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the head, FIG. 2 is a top view showing the nozzle plate of the head in a transparent state, FIG. 3 is a schematic cross-sectional view of the head along the diaphragm longitudinal direction, and FIG. FIG. 3 is a schematic cross-sectional explanatory view along the liquid chamber short direction of the head.

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

As the flow path substrate 1, a silicon substrate (first silicon substrate) is used, and a liquid chamber 6 and a vibration plate 10 that forms a bottom wall of the liquid chamber 6, and a partition wall 1 that separates the liquid chambers 6.
1 and a recess forming the common ink chamber 8 and the like.

The flow path substrate 1 diffuses boron, which is a high-concentration P-type impurity, into a silicon substrate to a thickness (depth) to be a diaphragm, and anisotropically etches the high-concentration boron diffusion layer as an etching stop layer. By performing a predetermined process while forming a concave portion or the like that becomes the liquid chamber 6 by performing the above process, the diaphragm 10 having a desired thickness is obtained by performing a predetermined process while leaving the high-concentration boron diffusion layer. Note that gallium, aluminum, or the like can be used as the high-concentration P-type impurity in addition to boron. Further, using a silicon oxide film or a silicon nitride film as an alkali anisotropic etching stop layer, and using a single crystal silicon (a substrate having this structure is generally called an SOI structure) or polycrystalline silicon as a main material of the diaphragm may be used. it can.

Further, an insulating film 20 is formed on a surface of the vibration plate 10 facing an electrode 15 described later. Here, the surface of the high-concentration boron diffusion layer on the electrode side is a polished surface, and the insulating film 20 is a 0.1 μm thick SiO ₂ film formed by thermal oxidation on the polished surface of the high-concentration boron diffusion layer. is there.

By providing the insulating film 20 in this manner, the reliability against dielectric breakdown and short circuit during driving is improved, and the electrode 15 is formed by repeating driving.
Charging of the insulating film 17 formed thereon can be suppressed, and a stable diaphragm displacement can be obtained.

Further, by using the insulating film 20 as a thermal oxide film, it is possible to improve insulation resistance and reliability (by reducing charge trapping and being excellent in moisture absorption resistance).
Further, since the insulating film 20 is formed by oxidizing the surface of the polished high-concentration B diffusion layer having a very small surface roughness, the surface of the insulating film 20 has a good surface property (atomic atom) having a very small surface roughness. Ra value is 0.5 nm or less as measured by an atomic force microscope). Thereby, it becomes easy to directly join the flow path substrate 1 and the electrode substrate 3.

The electrode substrate 3 has a thickness of 2 μm by a thermal oxidation method or the like.
An oxide film 3a having a depth of 0.1 m is formed on the oxide film 3a.
A recess 14 having a thickness of 3 μm is formed, and an electrode 15 is formed on the bottom surface of the recess 14 with a predetermined (0.2 μm) gap 16 provided on the diaphragm 10.
The diaphragm 15 is displaced by the
Constitutes an actuator section for changing the internal volume of the actuator.

The diaphragm 1 is provided on the electrode 15 of the electrode substrate 3.
In order to prevent the electrode 15 from being damaged by contact with 0, an insulating film (insulating layer) 17 such as a 0.1 μm thick silicon oxide film is formed. The electrode 15 has a lead portion 15a and an electrode pad portion 15b which extend to near the end of the electrode substrate 3 and are connected to an external drive circuit via connection means.

The electrode substrate 3 has a recess 14 formed on a silicon substrate (second silicon substrate) on which a thermal oxide film 3a is formed by etching with an HF solution or the like.
4, 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 to form recesses 14. Only the electrode 15 is formed.

Here, the electrode 15 is formed by sputtering titanium nitride to a thickness of 0.1 μm in a concave portion 14 having a depth of 0.4 μm formed by etching a silicon substrate.
Further, as described above, the insulating film 20 (here, a thermal oxide film having a thickness of 0.1 μm)
m). Therefore, in this head, the length of the gap 16 (the effective distance between the diaphragm 10 and the electrode 15) after joining the electrode substrate 3 and the flow path substrate 1 is:
It is 0.2 μm.

The channel substrate 1 as the first silicon substrate and the electrode substrate 2 as the second silicon substrate are directly joined. In this case, the electrode side surface (bonding surface) of the diaphragm 10 of the flow path substrate 1 is polished to reduce the surface roughness to R.
a = 0.5 nm or less. Thereby, the flow path substrate 1 and the electrode substrate 2 can be bonded firmly and with high reliability.

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.

In this ink jet head, a voltage of 0 V to 3 is applied to the electrode 15 by a driving circuit (driver IC).
When a pulse potential of 5 V is applied and the surface of the electrode 15 is positively charged, the corresponding lower surface of the diaphragm 10 is charged to a negative potential. Therefore, the diaphragm 10 bends downward due to the static electricity suction action. Next, the potential of the electrode 15 is turned off.
Then, the diaphragm 10 is restored. As a result, the pressure in the pressurizing chamber 6 sharply increases, and ink droplets are ejected from the nozzles 5. Next, when the diaphragm 10 bends toward the electrode 15 again, ink is supplied from the common liquid chamber 8 into the pressurizing chamber 6 through the fluid resistance part 7.

In this case, the diaphragm 10 is made of the electrode side insulating film 17.
When driven by the contact driving method of displacing until contact is made, the surface of the diaphragm 10 facing the electrode 15, that is, the surface contacting the insulating film 17 is a polished surface having very small surface roughness and good surface properties. Therefore, high reliability against dielectric breakdown of the insulating film 17 can be guaranteed.

Next, a first embodiment of a method for manufacturing an ink jet head (droplet discharge head) according to the present invention will be described with reference to FIGS. FIG.
(A), (b) and (c) and subsequent figures are shown with different scales. First, as shown in FIG. 5A, boron (B) is diffused to one side of a first silicon substrate 31 having a thickness of 200 μm and a crystal plane orientation (110) which has been mirror-polished on both sides, for example, by a solid state diffusion method. In addition, as the diffusion method, a vapor phase diffusion method using BBr ₃ , an ion implantation method, and a coating diffusion method in which B ₂ O ₃ is dispersed in an organic solvent and spin-coated on a wafer can be used.

As this solid diffusion, 1150 ° C. (O_Two:
N_Two= 0.25: 1) for 1 hour.
Peak value is 2E20 / cm³1E20 at 2.0 μm depth
/ Cm ³High-concentration B-doped silicon layer 41
In forming the high concentration B-doped silicon layer 41,
Glass layer 4 having a thickness of about 150 nm on the outermost surface of
3 is formed, the glass layer 43 and the high concentration B-doped silicon
Between layer 41 and silicon-boron about 30 nm thick
Alloy (SiB_4-6) Layer 42 was formed. In addition, glass
The layer can be removed with a hydrofluoric acid aqueous solution, as is well known.
The layer 42 cannot be removed with a hydrofluoric acid aqueous solution, and the alloy layer 42
Indicates hydrophilicity, and is directly exposed on the surface where the alloy layer 42 is exposed.
Cannot be joined.

Then, as shown in FIG. 3B, the CMP (CMP) is applied from the surface side of the glass layer 43 of the first silicon substrate 31.
The glass layer 43 and the alloy layer 42 are completely removed by performing chemical-mechanical-polishing (Ng).

In this CMP, as shown in FIG. 6, a wafer W attached to a polishing head 53 rotating at a predetermined carrier speed is rotated against a polishing pad 52 provided on a polishing plate 51 rotating at a predetermined table speed. Here, the surface to be polished of the first silicon substrate 31) is pressed with a predetermined pressure, and the polishing is performed while the slurry liquid 54 is dropped.

Here, as the slurry liquid 54, a KOH-based slurry containing colloidal silica diluted 1: 5 with deionized water was used. The pH value of the slurry liquid after dilution was 10.5. Polishing pad 5
For No. 2, a soft polishing pad used for mirror polishing of a silicon wafer was used.

The polishing conditions were as follows: table speed / carrier speed = 38 rpm / 25 rpm, polishing pressure = 100 g / cm ² polishing time = 5 minutes (the polishing rate was 65 nm / min. In the glass layer). After polishing, cleaning of wafer (RCA cleaning)
Was done.

The glass layer 43 and the alloy layer 42 were completely removed by the CMP, and the polished surface (the surface of the high-concentration B-doped silicon layer 41) after polishing showed water repellency. The polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) enabling direct bonding with high reliability was obtained.
I got

Then, the thermal oxide film (insulating film) 20 is
A wet oxidation ( ₆ sccm of O ₂ gas, 9 sccm of H ₂ gas) at 500 ° C. on the high-concentration boron-doped silicon layer 41 to a thickness of 500
Å formed. The surface of the thermal oxide film 20 was measured with an atomic force microscope, and as a result, a surface roughness value (Ra = 0.19 nm) was obtained at which highly reliable direct bonding was possible.

Next, as shown in FIG. 5C, the high-concentration B-doped silicon layer 41 of the first silicon substrate 31 was directly joined to the second silicon substrate 32 on which the electrode 15 was formed. Note that the gap dimension G of the second silicon substrate 32 is formed to be 0.2 μm.

This joining step is as follows. The first and second silicon substrates 31 and 32 are mixed with sulfuric acid and hydrogen peroxide (a mixture of sulfuric acid and hydrogen peroxide at a volume ratio of 2: 1) at a temperature of 1: 1.
After washing at 00 ° C. and drying, the first silicon substrate 31 and the second silicon substrate 32 are overlaid and
Heat treatment is performed at 00 ° C. for 2 hours. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Thereafter, as shown in FIG. 3D, the first silicon substrate 31 of the bonded substrate 33 is LP-CV
A silicon nitride film 44 is formed by D, and liquid chamber patterns such as the pressure chamber 6 and the common liquid chamber 8 are patterned on the silicon nitride film 44 by photolithography and etching techniques.

Next, the substrate 33 is made of KOH (10 wt /
%) Dipped in aqueous solution to etch silicon. Etching proceeds from the opening of the silicon nitride film 44, and when the boron concentration reaches a depth of 1E2- / cm ³ , the etching is stopped (etch rate is extremely reduced), and a diaphragm made of high-concentration boron-doped silicon 10 are formed. The thickness of the diaphragm 10 is 2 μm ± within the wafer plane.
The variation was reduced to 0.1 μm. Note that the variation caused by the CMP process is ±
Contains 0.05 μm.

As described above, after the high-concentration P-type impurity is diffused, the glass layer and the silicon-boron alloy layer are polished and removed by a polishing method such as CMP to remove the glass layer and the alloy layer and to form a diffusion surface serving as a bonding surface. The surface properties that can be directly bonded can be collectively formed, and highly reliable direct bonding can be performed in a short process.

Next, a second embodiment of the method for manufacturing an ink jet head according to the present invention will be described with reference to FIG. First, in the same manner as in the first embodiment, as shown in FIG. 7A, a double-sided mirror-polished first silicon substrate 31 having a thickness of 200 μm and a crystal plane orientation (110) is placed on one side by, for example, a solid diffusion method ( Boron (B) may be diffused by a gas phase diffusion method, an ion implantation method, a coating diffusion method, or the like.)

Next, as shown in FIG. 2B, the first silicon substrate 31 is placed in a hydrofluoric acid (HF: 10%) aqueous solution for 15 minutes.
After the glass layer 43 is removed by immersion for a minute, the alloy layer 42 is completely removed by performing CMP as shown in FIG.
The CMP used herein was the same as the first, except that a KOH-based slurry containing colloidal silica was diluted 1:10 with deionized water as a slurry liquid, and the polishing time was set to 2 minutes. This was performed in the same manner as in the embodiment. As a result, the polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) capable of highly reliable direct bonding was obtained.

Then, as shown in FIG. 4D, the thermal oxide film 20 is wet-oxidized at 900 ° C. (O ₂ gas 6 sccm, H ₂
High-concentration boron-doped silicon layer 41
It was formed on top with a film thickness of 500 °. The surface of the thermal oxide film 20 was measured with an atomic force microscope, and as a result, a surface roughness value (Ra = 0.19 nm) was obtained at which highly reliable direct bonding was possible.

Thereafter, as in the first embodiment (FIG. 5C)
), The high-concentration B-doped silicon layer 41 of the first silicon substrate 31 and the second silicon substrate 32 on which the electrode 15 was formed were directly joined to each other. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the first embodiment (FIG. 5D,
(See (e)) to form the diaphragm 10. Thereby, the variation caused by the CMP process is ± 0.02 μm.
Was suppressed. This is because the CMP is performed after the glass layer 43 is completely removed, so that the initial thickness of the glass layer 43 and the polishing variation of the glass layer 43 can be eliminated. As a result, the thickness of the diaphragm 10 is 2 μm in the wafer plane.
Variation of ± 0.07 μm could be suppressed.

As described above, after the high-concentration P-type impurity is diffused, the glass layer is removed by wet etching, and the silicon-boron alloy layer is polished and removed by a polishing method such as CMP. Control and highly reliable direct bonding are possible.

Next, a method for manufacturing an ink jet head according to a third embodiment of the present invention will be described with reference to FIG. First, as in the respective embodiments, as shown in FIG. 8A, a double-sided mirror-polished first silicon substrate 31 having a thickness of 200 μm and a crystal plane orientation (110) is placed on one side by, for example, a solid diffusion method (gas diffusion). Boron (B) may be diffused by a phase diffusion method, an ion implantation method, a coating diffusion method, or the like.

Next, as shown in FIG. 2B, the first silicon substrate 31 is immersed in a hydrofluoric acid (HF: 10%) aqueous solution for 15 minutes.
After the glass layer 43 is removed by immersion for a minute, the alloy layer 42 is thermally oxidized (oxygen and water vapor atmosphere, 750 ° C.-1 hr) as shown in FIG. (B ₂ O ₃ and SiO ₂ ) to form an oxide layer 45 that can be removed by etching with a hydrofluoric acid aqueous solution.

Then, as shown in FIG. 6D, the oxide layer 45 is removed with a hydrofluoric acid (HF: 10%) aqueous solution to expose the high-concentration B-doped silicon layer 41, The surface of No. 41 was polished by performing CMP. Note that the CMP conditions are the same as those described in the second embodiment. As a result, the polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) capable of highly reliable direct bonding was obtained.

Then, as shown in FIG. 5E, the thermal oxide film 20 is wet-oxidized at 900 ° C. (O ₂ gas 6 sccm, H ₂
High-concentration boron-doped silicon layer 41
It was formed on top with a film thickness of 500 °. The surface of the thermal oxide film 20 was measured with an atomic force microscope, and as a result, a surface roughness value (Ra = 0.19 nm) was obtained at which highly reliable direct bonding was possible.

Thereafter, as in the first embodiment (FIG. 5C)
), The high-concentration B-doped silicon layer 41 of the first silicon substrate 31 and the second silicon substrate 32 on which the electrode 15 was formed were directly joined to each other. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the first embodiment (FIG. 5D,
(See (e)) to form the diaphragm 10. As a result,
The thickness of the diaphragm 10 is 2 μm ± 0.0 in the wafer plane.
The variation was 7 μm.

As described above, the high concentration P of the first silicon substrate
The glass layer formed on the surface of the type impurity diffusion layer is removed by wet etching, the silicon-boron alloy layer is oxidized, and polished and removed by a polishing method such as CMP. Highly reliable direct bonding is possible.

Next, a method for manufacturing an ink jet head according to a fourth embodiment of the present invention will be described with reference to FIG. First, as shown in FIG. 9A, when boron is diffused to one side of a first silicon substrate 31 having a thickness of 200 μm and a crystal plane orientation of (110) which has been mirror-polished on both sides by a solid diffusion step, 1150 ° C. Of the one-hour drive, the first 50 minutes were mainly nitrogen gas (gas flow ratio O ₂ : N ₂ =
0.25: 1) drive, the remaining 10 minutes, and the drive during cooling down (cooling down to 750 ° C. at 3 ° C./min.) Were performed mainly with oxygen gas (gas flow ratio O ₂ : N ₂ = 1: 0). At a peak value of 2E20 / cm ³ and a depth of 2.0 μm,
A high concentration B-doped silicon layer 41 having a density of cm ³ is obtained,
About 200 nm thick on the high concentration B-doped silicon layer 41
Only the glass layer 43 is formed.

At this time, the reason why the above-mentioned alloy layer is not formed on the glass layer 43 is that the alloy layer is oxidized during the driving mainly with the oxygen gas (gas flow ratio O ₂ : N ₂ = 1: 0),
This is because it becomes a part of the glass layer 43.

Next, as shown in FIG. 2B, the first silicon substrate 31 is immersed in a hydrofluoric acid (HF: 10%) aqueous solution for 15 minutes.
The glass layer 43 was removed by immersion for a minute to expose the high-concentration B-doped silicon layer 41, and the surface of the high-concentration B-doped silicon layer 41 was polished by CMP as in the third embodiment. Note that the CMP conditions are the same as those described in the second embodiment. As a result, the polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) capable of highly reliable direct bonding was obtained.

Then, as shown in FIG. 3C, the thermal oxide film 20 is wet oxidized at 900 ° C. (O ₂ gas 6 sccm, H ₂
High-concentration boron-doped silicon layer 41
It was formed on top with a film thickness of 500 °. The surface of the thermal oxide film 20 was measured with an atomic force microscope, and as a result, a surface roughness value (Ra = 0.19 nm) was obtained at which highly reliable direct bonding was possible.

Thereafter, as in the first embodiment (FIG. 5C)
), The high-concentration B-doped silicon layer 41 of the first silicon substrate 31 and the second silicon substrate 32 on which the electrode 15 was formed were directly joined to each other. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the first embodiment (FIG. 5D,
(See (e)) to form the diaphragm 10. As a result,
The thickness of the diaphragm 10 is 2 μm ± 0.0 in the wafer plane.
The variation was 9 μm. It is considered that the reason why the variation slightly increases as compared with the third embodiment is that when the oxidation process of the alloy layer is in the course of diffusion, instability occurs in the gas flow at the time of gas switching.

As described above, while forming a high-concentration P-type impurity diffusion layer on one side of the first silicon substrate, the silicon-boron alloy layer is oxidized, and the glass layer and the silicon-boron alloy layer are oxidized. Polishing the high-concentration P-type impurity diffusion surface after removal by etching makes it possible to control the thickness of the diaphragm with high accuracy and to achieve highly reliable direct bonding.

Next, a method of manufacturing an ink jet head according to a fifth embodiment of the present invention will be described with reference to FIG. First, similarly to each embodiment, as shown in FIG. 10A, a double-sided mirror-polished first silicon substrate 31 having a thickness of 200 μm and a crystal plane orientation of (110) is placed on one side by, for example, a solid diffusion method (gas diffusion). Boron (B) may be diffused by a phase diffusion method, an ion implantation method, a coating diffusion method, or the like.

Next, as shown in FIG. 7B, the first silicon substrate 31 is immersed in a hydrofluoric acid (HF: 10%) aqueous solution for 15 minutes.
After the glass layer 43 is removed by immersion for a minute, the alloy layer 42 is thermally oxidized (oxygen and water vapor atmosphere, 750 ° C.-1 hr) as shown in FIG. (B ₂ O ₃ and SiO ₂ ) to form an oxide layer 45 that can be removed by etching with a hydrofluoric acid aqueous solution.

Therefore, as shown in FIG.
The oxide layer 45 is removed with a mixture of HNO ₃ : H ₂ O at a volume ratio of 1: 100: 100, and the high-concentration B-doped silicon layer 4 is removed.
1 was exposed and polished by CMP from the surface of the high concentration B-doped silicon layer 41. The condition of CMP is the second
This is the same as described in the embodiment. As a result, the polished surface was measured by an atomic force microscope, and as a result, the surface roughness value (Ra = 0.17 n
m) was obtained.

Then, as shown in FIG. 7E, the thermal oxide film 20 is wet oxidized at 900 ° C. (O ₂ gas 6 sccm, H ₂
High-concentration boron-doped silicon layer 41
It was formed on top with a film thickness of 500 °. The surface of the thermal oxide film 20 was measured with an atomic force microscope, and as a result, a surface roughness value (Ra = 0.19 nm) was obtained at which highly reliable direct bonding was possible.

Thereafter, as in the first embodiment (FIG. 5C)
), The high-concentration B-doped silicon layer 41 of the first silicon substrate 31 and the second silicon substrate 32 on which the electrode 15 was formed were directly joined to each other. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the first embodiment (FIG. 5D,
(See (e)) to form the diaphragm 10. As a result,
The thickness of the diaphragm 10 is 2 μm ± 0.0 in the wafer plane.
The variation was 9 μm.

As described above, the high concentration P of the first silicon substrate
By removing the glass layer formed on the surface of the impurity diffusion layer by wet etching and removing the silicon-boron alloy layer by wet etching and polishing, the highly accurate control of diaphragm thickness and high reliability Joining becomes possible.

Although it has been confirmed that a surface roughness value (Ra = 0.19 nm) that can be directly bonded can be obtained by forming the insulating film 20 on the polished surface by thermal oxidation as described above. In the case where a surface roughness value (Ra = 0.5 nm or less) that enables direct bonding cannot be obtained by using, the surface of the insulating film 20 can be polished by CMP or the like.

Next, a second embodiment of the ink jet head according to the present invention will be described with reference to FIGS. FIG. 11 is a schematic cross-sectional view of the head along the longitudinal direction of the diaphragm, and FIG. 12 is a schematic cross-sectional view of the head along the short side of the liquid chamber. The ink jet head includes the electrode substrate 3 of the insulating film (thermal oxide film) 20 formed on the electrode side surface of the diaphragm 10 in the first embodiment.
A portion corresponding to a joint with the (second silicon substrate) is removed. Other configurations are the same as those of the first embodiment.

By removing the thermal oxide film 20 at the joint between the flow path substrate 1 and the electrode substrate 3 as described above, an additional step such as a patterning step is required. Further improvement can be achieved.

Next, a third embodiment of the ink jet head according to the present invention will be described with reference to FIGS. FIG. 13 is a schematic cross-sectional view of the head along the longitudinal direction of the diaphragm, and FIG. 13 is a schematic cross-sectional view of the head in the lateral direction of the liquid chamber. This ink jet head does not form the insulating film (thermal oxide film) 20 on the electrode side surface of the vibration plate 10 in the first embodiment. Other configurations are the same as those of the first embodiment.

In the case of the head of this embodiment, the diaphragm 10
When driven by a contact driving method in which the diaphragm 10 is displaced until it comes into contact with the electrode-side insulating film 17, the surface of the diaphragm 10 facing the electrode 15, that is, the surface in contact with the insulating film 17 has a very small surface roughness and a good surface property. Therefore, high reliability can be guaranteed against dielectric breakdown of the insulating film 17.

Accordingly, a manufacturing method according to the present invention for manufacturing the ink jet head of the third embodiment is shown in FIG.
This will be described with reference to 5 and subsequent figures. First, a sixth embodiment of the method for manufacturing an ink jet head (droplet discharge head) according to the present invention will be described with reference to FIG. 15A, 15B and 15C are shown on different scales. First, as shown in FIG. 15 (a), both sides were mirror-polished, the thickness was 200 μm, and the crystal plane orientation (11
0) Boron (B) is diffused to one side of the first silicon substrate 31 by, for example, a solid state diffusion method. The diffusion method is
In addition, a gas phase diffusion method using BBr ₃ , an ion implantation method,
A coating diffusion method or the like in which B ₂ O ₃ is dispersed in an organic solvent and spin-coated on a wafer can also be used.

As this solid diffusion, 1150 ° C. (O_Two:
N_Two= 0.25: 1) for 1 hour.
Peak value is 2E20 / cm³1E20 at 2.0 μm depth
/ Cm ³High-concentration B-doped silicon layer 41
In forming the high concentration B-doped silicon layer 41,
Glass layer 4 having a thickness of about 150 nm on the outermost surface of
3 is formed, the glass layer 43 and the high concentration B-doped silicon
Between layer 41 and silicon-boron about 30 nm thick
Alloy (SiB_4-6) Layer 42 was formed. In addition, glass
The layer can be removed with a hydrofluoric acid aqueous solution, as is well known.
The layer 42 cannot be removed with a hydrofluoric acid aqueous solution, and the alloy layer 42
Indicates hydrophilicity, and is directly exposed on the surface where the alloy layer 42 is exposed.
Cannot be joined.

Therefore, as shown in FIG. 9B, the CMP (C
The glass layer 43 and the alloy layer 42 are completely removed by performing chemical-mechanical-polishing (Ng). This CMP
This method is the same as that described with reference to FIG.

The glass layer 43 and the alloy layer 42 were completely removed by the CMP, and the polished surface (the surface of the high-concentration B-doped silicon layer 41) after polishing showed water repellency. The polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) enabling direct bonding with high reliability was obtained.
I got

Next, as shown in FIG. 15C, a high concentration B-doped silicon layer 41 of the first silicon substrate 31 is formed.
The second silicon substrate 32 on which the electrode 15 was formed was directly faced and joined. Note that the gap dimension G of the second silicon substrate 32 is formed to be 0.2 μm.

This joining step is as follows. The first and second silicon substrates 31 and 32 are mixed with sulfuric acid and hydrogen peroxide (a mixture of sulfuric acid and hydrogen peroxide at a volume ratio of 2: 1) at a temperature of 1: 1.
After washing at 00 ° C. and drying, the first silicon substrate 31 and the second silicon substrate 32 are overlaid and
Heat treatment is performed at 00 ° C. for 2 hours. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Thereafter, as shown in FIG. 11D, the first silicon substrate 31 of the bonded substrate 33 is LP-CV
A silicon nitride film 44 is formed by D, and liquid chamber patterns such as the pressure chamber 6 and the common liquid chamber 8 are patterned on the silicon nitride film 44 by photolithography and etching techniques.

Next, the substrate 33 is made of KOH (10 wt /
%) Dipped in aqueous solution to etch silicon. Etching proceeds from the opening of the silicon nitride film 44, and when the boron concentration reaches a depth of 1E2- / cm ³ , the etching is stopped (etch rate is extremely reduced), and a diaphragm made of high-concentration boron-doped silicon 10 are formed. The thickness of the diaphragm 10 is 2 μm ± within the wafer plane.
The variation was reduced to 0.1 μm. Note that the variation caused by the CMP process is ±
Contains 0.05 μm.

As described above, after the high-concentration P-type impurity is diffused, the glass layer and the silicon-boron alloy layer are polished and removed by a polishing method such as CMP to remove the glass layer and the alloy layer and to form a diffusion surface serving as a bonding surface. The surface properties that can be directly bonded can be collectively formed, and highly reliable direct bonding can be performed in a short process.

Next, a seventh embodiment of the method for manufacturing an ink jet head according to the present invention will be described with reference to FIG. First, as in the sixth embodiment, FIG.
(A) As shown in FIG.
m, one side of the first silicon substrate 31 having the crystal plane orientation (110), for example, a solid state diffusion method (a gas phase diffusion method, an ion implantation method,
A coating diffusion method may be used. ) To diffuse boron (B).

Next, as shown in FIG. 9B, the first silicon substrate 31 is placed in a hydrofluoric acid (HF: 10%) aqueous solution for 15 minutes.
After the glass layer 43 is removed by immersion for a minute, the alloy layer 42 is completely removed by performing CMP as shown in FIG.
The CMP used herein was the same as the slurry except that a KOH-based slurry containing colloidal silica was diluted 1:10 with deionized water as a slurry liquid, and the polishing time was changed to 2 minutes. This was performed in the same manner as in the embodiment (quoting the first embodiment). As a result, the polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) capable of highly reliable direct bonding was obtained.

Then, similarly to the sixth embodiment (FIG. 15)
(C), the high concentration B of the first silicon substrate 31
The doped silicon layer 41 and the second silicon substrate 32 on which the electrode 15 was formed faced and directly joined. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the sixth embodiment (FIG. 15)
(See (d) and (e)) to form the diaphragm 10. As a result, the variation caused during the CMP process is ± 0.0
It was suppressed to 2 μm. This is because the glass layer 43 is completely removed and then subjected to CMP, so that the initial film thickness of the glass layer 43,
This is because variations in polishing of the glass layer 43 can be eliminated. As a result, the thickness of the diaphragm 10 could be suppressed to a variation of 2 μm ± 0.07 μm in the wafer plane.

As described above, after the high-concentration P-type impurity is diffused, the glass layer is removed by wet etching, and the silicon-boron alloy layer is polished and removed by a polishing method such as CMP. Control and highly reliable direct bonding are possible.

Next, a method for manufacturing an ink jet head according to the eighth embodiment of the present invention will be described with reference to FIG. First, as in the above embodiments, FIG.
(A) As shown in FIG.
m, one side of the first silicon substrate 31 having the crystal plane orientation (110), for example, a solid state diffusion method (a gas phase diffusion method, an ion implantation method,
A coating diffusion method may be used. ) To diffuse boron (B).

Next, as shown in FIG. 3B, the first silicon substrate 31 is immersed in a hydrofluoric acid (HF: 10%) aqueous solution for 15 minutes.
After the glass layer 43 is removed by immersion for a minute, the alloy layer 42 is thermally oxidized (oxygen and water vapor atmosphere, 750 ° C.-1 hr) as shown in FIG. (B ₂ O ₃ and SiO ₂ ) to form an oxide layer 45 that can be removed by etching with a hydrofluoric acid aqueous solution.

Therefore, as shown in FIG. 10D, the oxide layer 45 is removed with a hydrofluoric acid (HF: 10%) aqueous solution to expose the high-concentration B-doped silicon layer 41, The surface of No. 41 was polished by performing CMP. The conditions for CMP are the same as those described in the seventh embodiment. As a result, the polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) capable of highly reliable direct bonding was obtained.

Then, as in the sixth embodiment (FIG. 15)
(C), the high concentration B of the first silicon substrate 31
The doped silicon layer 41 and the second silicon substrate 32 on which the electrode 15 was formed faced and directly joined. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the sixth embodiment (FIG. 15)
(See (d) and (e)) to form the diaphragm 10. As a result, the thickness of the diaphragm 10 is 2 μm in the wafer plane.
Variation of ± 0.07 μm could be suppressed.

As described above, the high concentration P of the first silicon substrate
The glass layer formed on the surface of the type impurity diffusion layer is removed by wet etching, the silicon-boron alloy layer is oxidized, and polished and removed by a polishing method such as CMP. Highly reliable direct bonding is possible.

Next, a method of manufacturing an ink jet head according to the ninth embodiment of the present invention will be described with reference to FIG. First, as shown in FIG. 18 (a), when boron is diffused into one side of the first silicon substrate 31 having a thickness of 200 μm and a crystal plane orientation (110) which has been mirror-polished on both sides by a solid diffusion step, 1150 ° C. Of the one-hour drive, the first 50 minutes were mainly nitrogen gas (gas flow ratio O ₂ : N
₂ = 0.25: 1), drive for the remaining 10 minutes and during cooling down (cooling down to 750 ° C. at 3 ° C./min.) With a drive mainly composed of oxygen gas (gas flow ratio O ₂ : N ₂ = 1: 0). As a result, the peak value was 2E20 / cm ³ , and the peak value was 1E20 / 2.0 μm.
/ Cm ³ of the high-concentration B-doped silicon layer 41, and a thickness of about 200
Only the glass layer 43 of nm is formed.

At this time, the reason that the above-mentioned alloy layer is not formed on the glass layer 43 is that the alloy layer is oxidized during the driving mainly using the oxygen gas (gas flow ratio O ₂ : N ₂ = 1: 0), This is because it becomes a part of the glass layer 43.

Next, as shown in FIG. 13B, the first silicon substrate 31 is immersed in an aqueous solution of hydrofluoric acid (HF: 10%) for 15 minutes.
The glass layer 43 was removed by immersion for a minute to expose the high-concentration B-doped silicon layer 41, and the surface of the high-concentration B-doped silicon layer 41 was polished by CMP as in the third embodiment. The conditions for CMP are the same as those described in the sixth embodiment. Thereby, the polished surface is
As a result of measurement with an atomic force microscope, a surface roughness value (Ra = 0.17 nm) capable of highly reliable direct bonding was obtained.

Then, similarly to the sixth embodiment (FIG. 15)
(C), the high concentration B of the first silicon substrate 31
The doped silicon layer 41 and the second silicon substrate 32 on which the electrode 15 was formed faced and directly joined. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the sixth embodiment (FIG. 15)
(See (d) and (e)) to form the diaphragm 10. As a result, the thickness of the diaphragm 10 is 2 μm in the wafer plane.
The variation was ± 0.09 μm. It is considered that the reason why the variation slightly increases as compared with the third embodiment is that when the oxidation process of the alloy layer is in the course of diffusion, instability occurs in the gas flow at the time of gas switching.

As described above, while forming the high-concentration P-type impurity diffusion layer on one side of the first silicon substrate and oxidizing the silicon-boron alloy layer, the oxidized layer of this glass layer and silicon-boron alloy layer is wetted. Polishing the high-concentration P-type impurity diffusion surface after removal by etching makes it possible to control the thickness of the diaphragm with high accuracy and to achieve highly reliable direct bonding.

Next, a method for manufacturing an ink jet head according to the tenth embodiment of the present invention will be described with reference to FIG. First, in the same manner as described above, as shown in FIG. , An ion implantation method, a coating diffusion method, etc.).

Next, as shown in FIG. 13B, the glass layer 43 is polished by performing CMP from the surface of the glass layer 43 of the first silicon substrate 31. The polishing time was one minute. At this time, the glass layer 43 is left on the entire surface of the wafer. As a result, the polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17 nm) capable of highly reliable direct bonding was obtained.

Then, as shown in FIG. 19C, the glass layer 43 of the first silicon substrate 31 and the second silicon substrate 32 on which the electrode 15 was formed were directly joined to each other. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the sixth embodiment (FIG. 15)
(See (d) and (e)) to form the diaphragm 10. As a result, the thickness of the diaphragm 10 is 2 μm in the wafer plane.
Variation of ± 0.05 μm could be suppressed. However, gap length (distance between diaphragm 10 and electrode 15)
Of the other embodiment is 0.2 ± 0.
In this embodiment, 0.2 ± 0.1 μm.
It was as large as 0.04 μm.

As described above, the high concentration P of the first silicon substrate
By polishing and removing part of the glass layer formed on the surface of the impurity diffusion layer and bonding it directly to the second silicon substrate, high-precision control of diaphragm thickness and direct bonding with high reliability are possible. Become.

Next, a method for manufacturing an ink jet head according to the eleventh embodiment of the present invention will be described with reference to FIG. First, as in the above embodiments, FIG.
(A) As shown in FIG.
m, one side of the first silicon substrate 31 having the crystal plane orientation (110), for example, a solid state diffusion method (a gas phase diffusion method, an ion implantation method,
A coating diffusion method may be used. ) To diffuse boron (B).

Next, as shown in FIG. 13B, the first silicon substrate 31 is immersed in a hydrofluoric acid (HF: 10%) aqueous solution for 15 minutes.
After the glass layer 43 is removed by immersion for a minute, the alloy layer 42 is thermally oxidized (oxygen and water vapor atmosphere, 750 ° C.-1 hr) as shown in FIG. (B ₂ O ₃ and SiO ₂ ) to form an oxide layer 45 that can be removed by etching with a hydrofluoric acid aqueous solution.

Therefore, as shown in FIG.
The oxide layer 45 is removed with a mixture of HNO ₃ : H ₂ O at a volume ratio of 1: 100: 100, and the high-concentration B-doped silicon layer 4 is removed.
1 was exposed and polished by CMP from the surface of the high concentration B-doped silicon layer 41. The conditions for CMP are the same as those described in the seventh embodiment. This allows
The polished surface was measured by an atomic force microscope, and as a result, a surface roughness value (Ra = 0.17) allowing direct bonding with high reliability was obtained.
nm).

Then, similarly to the sixth embodiment (FIG. 15)
(C), the high concentration B of the first silicon substrate 31
The doped silicon layer 41 and the second silicon substrate 32 on which the electrode 15 was formed faced and directly joined. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as in the sixth embodiment (FIG. 15)
(See (d) and (e)) to form the diaphragm 10. As a result, the thickness of the diaphragm 10 is 2 μm in the wafer plane.
The variation was ± 0.09 μm.

As described above, the high concentration P of the first silicon substrate
By removing the glass layer formed on the surface of the impurity diffusion layer by wet etching and removing the silicon-boron alloy layer by wet etching and polishing, the highly accurate control of diaphragm thickness and high reliability Joining becomes possible.

Next, a method for manufacturing an ink jet head according to the twelfth embodiment of the present invention will be described. In this embodiment, in the polishing step in the seventh embodiment (see FIG. 16), instead of the CMP, a spin etching method (spin etching is a method in which a desired etching solution is applied to a rotating wafer and uniform over the entire surface. This is a wet processing method capable of performing various types of processing.). Polishing by the spin etching method involves applying H
A mixture of F: HNO ₃ : H ₂ O at a volume ratio of 1: 100: 100 is applied, and the alloy layer 42 and the high-concentration B-doped silicon layer 4 are applied.
1 was etched by about 1 μm. The uniformity of the etching amount is ± 5% over the entire surface of the wafer, and the surface roughness of the high-concentration B-doped silicon layer 41 after etching is Ra.
= 0.50 nm was obtained. The other steps and functions and effects are the same as in the seventh embodiment, and a description thereof will be omitted.

Next, a thirteenth embodiment of the method of manufacturing an ink jet head according to the present invention will be described with reference to FIGS.
This will be described with reference to FIG. First, as shown in FIG. 21A, boron (B) is diffused to one side of a first silicon substrate 61 having a thickness of 500 μm and a crystal plane orientation (110), which has been mirror-polished on both sides, for example, by a solid state diffusion method. In addition, as the diffusion method, a vapor phase diffusion method using BBr ₃ , an ion implantation method, and a coating diffusion method in which B ₂ O ₃ is dispersed in an organic solvent and spin-coated on a wafer can be used.

As this solid diffusion, 1150 ° C. (O ₂ :
(N ₂ = 0.25: 1), the diffusion was performed for 1 hour. As a result, the peak value was 1.5E20 / cm ³ , and the peak value was 1E at 2.0 μm.
A high-concentration B-doped silicon layer 71 having a thickness of 20 / cm ³ is obtained. When the high-concentration B-doped silicon layer 71 is formed, a glass layer 73 having a thickness of about 150 nm is formed on the outermost surface of the silicon substrate 61. A silicon-boron alloy (SiB _4-6 ) layer 72 having a thickness of about 30 nm was formed between the layer 73 and the high concentration B-doped silicon layer 71.

Therefore, as shown in FIG. 14B, the first silicon substrate 61 is immersed in a hydrofluoric acid (HF: 10%) aqueous solution.
After the glass layer 73 is removed by immersion for a minute, the alloy layer 72 is completely removed by performing CMP from the surface side of the glass layer 73 of the first silicon substrate 61 as shown in FIG.

In this CMP, a KOH-based slurry containing fumed silica diluted 1: 2 with deionized water was used as a slurry liquid. The pH value of the slurry liquid after dilution was 10.8. In addition, a soft polishing pad used for mirror polishing of a silicon wafer was used as the polishing pad.

Since the polishing rate of the slurry varies depending on the material to be polished, it is preferable to select an optimum slurry for the material to be polished. It is also preferable to select a polishing pad to be used depending on the substrate to be polished. For example, IC1000 / SUBA, which is often used for polishing an oxide film, may be used. However, in order to further reduce the surface roughness, a soft polishing pad (such as surfing) used for mirror polishing or finish polishing of a silicon wafer. It is preferable to use On the other hand, when the substrate to be polished is patterned, if the bottom surface of the concave pattern is not polished due to the softness of the pad and the concave shape is not allowed to change, the IC1000 / S
It is possible to polish only the bonding surface by using a pad of a UBA or harder type.

The polishing conditions were as follows: table speed / carrier speed = 38 rpm / 25 rpm, polishing pressure = 100 g / cm ² polishing time = 2 minutes (the polishing rate was 45 nm / min. For the glass layer). After polishing, the wafer was washed.

In this cleaning, scrub cleaning (1% HF dip) was performed for 1 minute, and pure water rinse was performed for 20 minutes. If cleanliness is further required, sulfuric acid and hydrogen peroxide (H ₂ SO ₄ : H ₂ O ₂ :: H ₂ O = 1: 1) is used to remove contaminants.
1: 5) Cleaning and cleaning with ammonia and hydrogen peroxide (NH ₄ OH: H
₂ O: H ₂ O = 1: 1: 5) and the like are preferably added to this.

By this polishing, the alloy (SiB _4-6 )
While the layer 72 is polished and removed, the surface roughness enabling direct bonding with high reliability (measured by an atomic force microscope,
Surface roughness (Ra = 0.2 nm: measurement area is 10 μm
A high concentration B-doped silicon layer 71 having □)) is obtained.

In this polishing process, the alloy layer 72 and a part of the high-concentration B-doped silicon layer 71 thereunder were polished and removed, but the polishing removal amount (thickness) of the high-concentration B-doped silicon layer 71 was reduced. Since the fluctuation directly changes the thickness of the diaphragm, it is necessary to control the polishing removal amount with high accuracy. For this purpose, the polishing amount is kept small (preferably 2,000 ° or less). Here, the high concentration B-doped silicon layer 71
Polishing amount (storage allowance) is 900 mm and the variation of polishing amount is ±
It was 150 ° or less.

Next, as shown in FIG.
4, a second silicon substrate 62 on which the electrodes 15 and the like are formed;
The high-concentration boron-doped silicon layer 71 obtained by polishing the surface of the first silicon substrate 61 was directly bonded as a bonding surface. Specifically, the first and second silicon substrates 61 and 62 are mixed with sulfuric acid / hydrogen peroxide (sulfuric acid and hydrogen peroxide at a volume ratio of 2: 1 at a temperature of 1: 1).
After cleaning and drying, the first and second silicon substrates 61 and 62 are overlapped under reduced pressure (room temperature) and subjected to a heat treatment in a nitrogen atmosphere at 900 ° C. for 1 hour.
1, 62 were directly joined. As a result, a strong bonding state without voids and maintaining the gap dimension with high precision was obtained.

Next, as shown in FIG.
The first silicon substrate 61 of 00 μm is thinned by polishing to a thickness of 100 μm. Thereafter, as shown in FIG. 2C, a silicon nitride film 74 is formed on the entire bonded substrate 63 by LP-CVD, a resist is coated on the silicon nitride film 74, and the discharge chamber 6 and the common A resist pattern having a liquid chamber shape such as the ink chamber 8 is formed. At this time, alignment is performed by IR light so that the position of the electrode 15 of the second silicon substrate 62 and the position of the pattern of the ejection chamber coincide. Then, as shown in FIG. 4D, the silicon nitride film 74 in the opening of the resist is removed by dry etching to remove the resist.

Then, the substrate 63 is made of KOH (10 wt%).
Immerse in an aqueous solution and etch silicon. Etching proceeds from the opening on the patterned side and the boron concentration is 1
When the depth reaches E20 / cm ³ , the etching is stopped (the etch rate is extremely lowered), and as shown in FIG. Are formed.

The thickness of the diaphragm 10 thus formed could be suppressed to 2 μm ± 0.1 μm in the wafer plane. In addition, this variation includes CMP
The variation (± 0.015 μm) due to the process is included.

Next, a fourteenth embodiment of the method for manufacturing an ink jet head according to the present invention will be described with reference to FIG. First, as shown in FIG. 1A, boron (B) is diffused to one side of a first silicon substrate 61 having a thickness of 500 μm and a crystal plane orientation (110), which has been mirror-polished on both sides, for example, by a solid state diffusion method.

As this solid diffusion, 1150 ° C. (O ₂ :
(N ₂ = 0.25: 1), the diffusion was performed for 1 hour. As a result, the peak value was 1.5E20 / cm ³ , and the peak value was 1E at 2.0 μm.
A high-concentration B-doped silicon layer 71 having a thickness of 20 / cm ³ is obtained. When the high-concentration B-doped silicon layer 71 is formed, a glass layer 73 having a thickness of about 150 nm is formed on the outermost surface of the silicon substrate 61. A silicon-boron alloy (SiB _4-6 ) layer 72 having a thickness of about 30 nm was formed between the layer 73 and the high concentration B-doped silicon layer 71.

Therefore, as shown in FIG. 14B, the first silicon substrate 61 is immersed in a hydrofluoric acid (HF: 10%) aqueous solution.
After the glass layer 73 is removed by immersion for a minute, the alloy layer 72 and a silicon layer under the alloy layer 72 containing many crystal defects are oxidized to form an oxide film 75 as shown in FIG. The oxidation was performed at 800 ° C. (O ₂ gas 6 sccm, H ₂ gas 9 sccm) for 60 minutes. This oxidation step is preferably performed at a low temperature of 800 ° C. or lower. Accordingly, it is possible to suppress a change in the boron concentration profile that affects the stop position of the alkali anisotropic etching in the subsequent process, and to suppress the propagation of crystal defects that easily occur at high temperatures. Here, an oxide film 75 of 1200 ° was formed. Therefore,
The oxide film 75 is removed with a hydrofluoric acid (HF: 10%) aqueous solution, and the surface roughness (Ra = 0.9 nm: measurement area is 10 μm).
A high concentration B-doped silicon layer 71 having m □) is obtained.

In this state, the surface is not polished to such a level that a highly reliable direct bonding can be performed. Since the alloy layer 72 and the defect layer are removed by the oxidation process, the polishing rate can be kept extremely stable, and the polishing accuracy can be improved as compared with the eighth embodiment. The polishing conditions here are such that the slurry liquid is a KOH-based slurry containing fumed silica (SEMI-SPRESE25: trade name)
Was diluted 1: 1 with deionized water.

The polishing conditions here were as follows. Table speed / Carrier speed = 38 rpm / 25 rpm Polishing pressure = 125 g / cm ² Polishing time = 1 minute (The polishing rate was 70 nm / min.)

By this polishing, the surface roughness (Ra = 0.15 nm, as measured by an atomic force microscope, which enables highly reliable direct bonding)
A high-concentration B-doped silicon layer 71 having μm □)) was obtained. In this embodiment, the polishing amount (storage allowance) is 700.
Although the polishing time was 1 minute in Å, the variation in the polishing amount was ± 50 ° or less in the wafer surface.

Hereinafter, a diaphragm was formed in the same manner as in the thirteenth embodiment (see FIG. 22).

[0146]

In each of the embodiments described above, the present invention is applied to an electrostatic ink jet head. However, in addition to the ink jet head for discharging ink droplets, for example, a liquid droplet discharge for discharging a liquid resist may be used. The same can be applied to a head and the like.

[0148]

As described above, according to the method of manufacturing a droplet discharge head according to the first aspect of the present invention, the glass layer and the silicon layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate are formed. -Since the boron alloy layer is polished and removed, direct bonding with high reliability can be performed in a short process, the density of the head can be increased, and the reliability is improved.

According to the method of manufacturing a droplet discharge head according to the present invention, the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate is removed by wet etching. Since the alloy layer is polished and removed, the thickness of the diaphragm can be controlled with high precision, and direct bonding can be performed with high reliability, so that the density of the head can be increased and the reliability of the head can be improved.

According to the third aspect of the present invention, the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate is removed by wet etching. Since the alloy layer is oxidized to remove the oxide layer and the high-concentration P-type impurity diffusion surface is polished, the thickness of the diaphragm can be controlled with high accuracy, and the direct bonding with high reliability can be performed. The density of the head can be increased, and the reliability can be improved.

According to the method of manufacturing a droplet discharge head according to the fourth aspect of the present invention, a silicon-boron alloy layer is oxidized while forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate. Since the glass layer and the layer formed by oxidizing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate are removed by wet etching and polished, the thickness of the diaphragm can be controlled with high precision. At the same time, direct bonding with high reliability can be performed, the density of the head can be increased, and the reliability can be improved.

According to the method of manufacturing a droplet discharge head according to the fifth aspect of the present invention, a part of the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate is polished and removed.
Since the polished surface is used as the bonding surface, the thickness of the diaphragm can be controlled with extremely high precision, the density of the head can be increased, and the reliability can be improved.

According to the method of manufacturing a droplet discharge head according to the sixth aspect of the present invention, the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate is removed by wet etching. Since the alloy layer is removed by wet etching and polished, highly reliable direct bonding can be performed, the density of the head can be increased, and the reliability of the head can be improved.

According to the method of manufacturing a droplet discharge head according to the present invention, the glass layer and the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate are polished and removed. Since an insulating film is formed on the polished surface,
High reliability direct bonding can be performed in a short process, and the density of the head can be increased, reliability is improved, and reliability against dielectric breakdown and short circuit is improved, resulting in stable diaphragm displacement characteristics. Can be

According to the method of manufacturing a droplet discharge head according to the eighth aspect of the present invention, the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate is removed by wet etching. Since the alloy layer is polished and removed, and an insulating film is formed on the polished surface, the thickness of the diaphragm can be controlled with high precision, and direct bonding with high reliability can be performed. As the reliability of the head is improved, the reliability against dielectric breakdown and short circuit is also improved, and stable diaphragm displacement characteristics can be obtained.

According to the ninth aspect of the present invention, the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate is removed by wet etching. The alloy layer is oxidized to remove the oxide layer, the high-concentration P-type impurity diffusion surface is polished, and the insulating film is formed on the polished surface. Bonding can be performed, the density of the head can be increased, reliability can be improved, and reliability against dielectric breakdown and short-circuit can be improved, and stable diaphragm displacement characteristics can be obtained.

According to the method of manufacturing a droplet discharge head according to the tenth aspect of the present invention, the high concentration P is formed on one side of the first silicon substrate.
A silicon-boron alloy layer is oxidized while forming a p-type impurity diffusion layer, and a glass layer and a silicon-boron alloy layer formed on the surface of the high-concentration p-type impurity diffusion layer of the first silicon substrate are wetted. Since it is removed by etching and polished, and an insulating film is formed on the polished surface, the thickness of the diaphragm can be controlled with high precision, and highly reliable direct bonding can be performed, and the density of the head can be increased. In addition, the reliability is improved, and the reliability against dielectric breakdown and short circuit is also improved, so that stable diaphragm displacement characteristics can be obtained.

According to the method of manufacturing a droplet discharge head according to the eleventh aspect, the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate is removed by wet etching. Since the alloy layer is removed by wet etching and polished, and an insulating film is formed on the polished surface, high-reliability direct bonding becomes possible, and the density of the head is increased, and the reliability of the head is improved. The reliability against dielectric breakdown and short circuit is also improved, and stable diaphragm displacement characteristics can be obtained.

In the method of manufacturing a droplet discharge head according to the present invention including the step of forming these insulating films, by removing at least the insulating film at the joint with the second silicon substrate, it is possible to lower the bonding temperature and to reduce the bonding temperature. The joint reliability can be further improved. Further, since the insulating film is a thermal oxide film, insulation resistance and further reliability can be improved. Further, when the surface roughness of the insulating film does not exceed Ra = 0.5 nm, direct bonding with high reliability is facilitated.

In the method of manufacturing a droplet discharge head according to each of these inventions, the use of high-concentration boron as the high-concentration P-type impurity simplifies the manufacturing process. In the polishing step, a highly accurate surface property can be obtained by polishing by a chemical mechanical polishing method using an aqueous solution having a hydroxyl group in the slurry liquid. In the polishing step, polishing is performed by a spin etching method, so that the process becomes simple and inexpensive, and the cost of the head can be reduced.

According to the droplet discharge head of the present invention, both the first substrate provided with the vibration plate and the second substrate provided with the electrodes are made of a silicon substrate, and the first and second substrates are at least one of them. The surface that has been polished is used as the bonding surface, and it is configured to be directly bonded, enabling direct bonding with high reliability, achieving higher precision and higher density of the head, and improving high reliability. can do.

Here, by forming an insulating film having a polished surface on the surface of the diaphragm facing the electrode, dielectric breakdown,
The reliability against short-circuit is improved, and stable diaphragm displacement characteristics can be obtained. Further, since the diaphragm is composed of the high-concentration P-type impurity silicon layer, the thickness of the diaphragm can be controlled with high accuracy. Furthermore, direct bonding can be performed with high reliability because the surface roughness of the polished surface does not exceed Ra = 0.5 nm.

According to the droplet discharge head of the present invention, a layered structure is formed in which at least the first substrate provided with the diaphragm and the second substrate provided with the electrodes are overlapped and joined, and the first substrate is formed of a silicon substrate. And a polished P-type impurity diffusion layer, and an insulating film formed on the polished surface of the P-type impurity diffusion layer is provided on the surface of the diaphragm facing the electrode, thereby achieving high reliability. Can be directly bonded, the reliability against dielectric breakdown and short circuit can be improved, the head can be made more accurate and the density can be increased, and the reliability can be improved.

Here, since the insulating film at least at the joint portion with the second silicon substrate is removed, the joining temperature is lowered and the joining reliability is further improved. Further, since the insulating film is a thermal oxide film, insulation resistance and reliability are further improved. Further, when the surface roughness of the insulating film does not exceed Ra = 0.5 nm, direct bonding with high reliability is facilitated.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of an electrostatic inkjet head as a droplet discharge head according to the invention.

FIG. 2 is an explanatory top view showing a nozzle plate of the head in a transmission state;

FIG. 3 is a schematic cross-sectional explanatory view of the head along a longitudinal direction of a diaphragm.

FIG. 4 is a schematic cross-sectional explanatory view of the head along a lateral direction of a diaphragm.

FIG. 5 is an explanatory diagram for explaining a first embodiment of a method for manufacturing a head according to the present invention;

FIG. 6 is an explanatory view for explaining the polishing step of FIG. 5;

FIG. 7 is an explanatory diagram for explaining a second embodiment of the method for manufacturing a head according to the present invention;

FIG. 8 is an explanatory diagram for explaining a third embodiment of the method for manufacturing a head according to the present invention;

FIG. 9 is an explanatory view for explaining a fourth embodiment of the method for manufacturing a head according to the present invention;

FIG. 10 is an explanatory view which is used for describing a fifth embodiment of the method for manufacturing a head according to the present invention.

FIG. 11 is a schematic cross-sectional explanatory view showing a second embodiment of an electrostatic inkjet head as a droplet discharge head according to the present invention, taken along a longitudinal direction of a diaphragm.

FIG. 12 is a schematic cross-sectional explanatory view of the head along the transverse direction of the diaphragm.

FIG. 13 is a schematic cross-sectional explanatory view showing a third embodiment of an electrostatic inkjet head as a droplet discharge head according to the present invention, taken along the longitudinal direction of the diaphragm.

FIG. 14 is a schematic cross-sectional explanatory view of the same head along the transverse direction of the diaphragm.

FIG. 15 is an explanatory view which is used for describing a sixth embodiment of the method for manufacturing a head according to the present invention.

FIG. 16 is an explanatory view serving to explain a seventh embodiment of the method for manufacturing a head according to the present invention;

FIG. 17 is an explanatory view which is used for describing an eighth embodiment of the method for manufacturing a head according to the present invention.

FIG. 18 is an explanatory diagram for explaining a ninth embodiment of a method for manufacturing a head according to the invention;

FIG. 19 is an explanatory view serving to explain a tenth embodiment of a method for manufacturing a head according to the present invention;

FIG. 20 is an explanatory view serving to explain an eleventh embodiment of a method for manufacturing a head according to the present invention;

FIG. 21 is an explanatory view serving to explain a thirteenth embodiment of a head manufacturing method according to the present invention;

FIG. 22 is an explanatory diagram provided for description of a process following FIG. 21;

FIG. 23 is an explanatory view serving to explain a fourteenth embodiment of a method for manufacturing a head according to the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flow path substrate, 3 ... Electrode substrate, 4 ... Nozzle plate, 5 ... Nozzle, 6 ... Liquid chamber, 10 ... Vibration plate, 15 ... Electrode, 20 ... Insulating film, 31, 61 ... First silicon substrate, 32, 62: second silicon substrate, 41, 71: high-concentration boron-doped silicon layer, 42, 72: silicon-boron alloy layer, 43, 7
3 ... Glass layer.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Makoto Tanaka 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C057 AF93 AG54 AP02 AP26 AP33 AP34 AP56 AQ02 BA05 BA14 BA15

Claims (25)

[Claims] A nozzle for discharging a droplet, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Polishing and removing the glass layer and the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate; and a step of providing the high-concentration P-type impurity diffusion layer of the first silicon substrate and the electrode. A step of bonding the two silicon substrates facing each other by direct bonding, and a step of forming the vibration plate by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate. Of manufacturing a droplet discharge head. 2. A nozzle for discharging droplets, a liquid chamber to which the nozzle communicates, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Removing the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate by wet etching; and removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate. A step of polishing and removing, a step of directly bonding the high-concentration P-type impurity diffusion layer of the first silicon substrate and the second silicon substrate provided with the electrodes, and bonding the second silicon substrate by direct bonding; Forming the vibrating plate by subjecting the first silicon substrate to alkali anisotropic etching. 3. A nozzle for discharging liquid droplets, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Removing the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate by wet etching; and removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate. A step of oxidizing; a step of removing the oxide layer of the silicon-boron alloy layer; a step of polishing the high-concentration P-type impurity diffusion surface; and a high-concentration P-type impurity diffusion layer of the first silicon substrate and the electrode. Bonding the first silicon substrate bonded to the second silicon substrate by direct bonding and facing the second silicon substrate provided with And forming the vibration plate by performing etching. 4. A nozzle for discharging droplets, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
In a method of manufacturing a droplet discharge head for discharging a droplet from the nozzle by displacing and deforming the diaphragm, a silicon-boron alloy is formed while forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate. A step of oxidizing the layer; a step of oxidizing the glass layer and the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate by wet etching; Polishing the type impurity diffusion surface; bonding a high-concentration P-type impurity diffusion layer of the first silicon substrate to the second silicon substrate provided with the electrodes by direct bonding; Forming the vibrating plate by alkali anisotropic etching of the first silicon substrate bonded to the liquid droplet discharging head. Manufacturing method. 5. A nozzle for discharging liquid droplets, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Polishing and removing a part of the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate; and a second silicon substrate provided with the high-concentration P-type impurity diffusion layer of the first silicon substrate and the electrode. And a step of bonding the first silicon substrate bonded to the second silicon substrate by alkali anisotropic etching to form the vibration plate. A method for manufacturing a droplet discharge head. 6. A nozzle for discharging droplets, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Removing the glass layer formed on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate by wet etching; and removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer by wet etching. Polishing the high-concentration P-type impurity diffusion surface; and bonding the high-concentration P-type impurity diffusion layer of the first silicon substrate to the second silicon substrate provided with the electrodes by direct bonding. And a step of forming the diaphragm by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate. Method for manufacturing a droplet discharge head according to symptoms. 7. A nozzle for discharging droplets, a liquid chamber to which the nozzle communicates, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Polishing and removing the glass layer and the silicon-boron alloy layer on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate; forming an insulating film on the surface of the high-concentration P-type impurity diffusion layer; And bonding the first silicon substrate bonded to the second silicon substrate with the second silicon substrate provided with the electrodes, and forming the diaphragm by alkali anisotropic etching of the first silicon substrate bonded to the second silicon substrate. A method for manufacturing a droplet discharge head. 8. A nozzle for discharging droplets, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Removing the glass layer on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate by wet etching; and polishing and removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate. A step of forming an insulating film on the surface of the high-concentration P-type impurity diffusion layer; a step of directly bonding the first silicon substrate and a second silicon substrate provided with electrodes; Forming the vibrating plate by subjecting the bonded first silicon substrate to alkali anisotropic etching. 9. A nozzle for discharging droplets, a liquid chamber communicating with the nozzle, a diaphragm forming a wall surface of the liquid chamber,
Forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate in a method of manufacturing a droplet discharge head that discharges droplets from the nozzle by displacing and deforming the vibration plate; Removing the glass layer on the surface of the high-concentration P-type impurity diffusion layer of the silicon substrate by wet etching; and oxidizing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate Removing the oxide layer of the silicon-boron alloy layer; polishing the high-concentration P-type impurity diffusion surface; forming an insulating film on the surface of the high-concentration P-type impurity diffusion layer; A step of directly bonding the first silicon substrate and the second silicon substrate provided with the electrodes, and a step of bonding the first silicon substrate bonded to the second silicon substrate with an alkali anisotropic material. Forming the vibrating plate by reactive etching. 10. A nozzle for discharging droplets, a liquid chamber to which the nozzle communicates, a vibration plate forming a wall surface of the liquid chamber, and a liquid droplet from the nozzle by displacing and deforming the vibration plate. A method of manufacturing a droplet discharge head for discharging, a step of forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate and oxidizing a silicon-boron alloy layer; Removing, by wet etching, a layer obtained by oxidizing the glass layer and the silicon-boron alloy layer on the surface of the high concentration P-type impurity diffusion layer; polishing the high concentration P-type impurity diffusion surface; Forming an insulating film on the first silicon substrate and bonding the first silicon substrate and the second silicon substrate provided with the electrodes by direct bonding; and bonding the first silicon substrate and the second silicon substrate to the second silicon substrate. Method for manufacturing a droplet discharge head, wherein a silicon substrate with an alkali anisotropic etching and forming the diaphragm. 11. A nozzle for discharging droplets, a liquid chamber to which the nozzle communicates, a vibration plate forming a wall surface of the liquid chamber, and a displacement of the vibration plate to cause droplets to be discharged from the nozzle. In a method for manufacturing a droplet discharge head for discharging, a step of forming a high-concentration P-type impurity diffusion layer on one side of a first silicon substrate; and a step of wetting the glass layer on the surface of the high-concentration P-type impurity diffusion layer of the first silicon substrate. A step of removing the silicon-boron alloy layer formed on the surface of the high-concentration P-type impurity diffusion layer by wet etching; a step of polishing the high-concentration P-type impurity diffusion surface; Forming an insulating film on the surface of the concentration P-type impurity diffusion layer; bonding the first silicon substrate and a second silicon substrate provided with electrodes by direct bonding; Forming the vibrating plate by subjecting the first silicon substrate bonded to the plate to alkaline anisotropic etching. 12. The method of manufacturing a droplet discharge head according to claim 7, wherein at least the insulating film at a joint portion with a second silicon substrate is removed. A method for manufacturing a discharge head. 13. The method for manufacturing a droplet discharge head according to claim 7, wherein the insulating film is a thermal oxide film. 14. The method according to claim 7, wherein the surface roughness of the insulating film does not exceed Ra = 0.5 nm. Manufacturing method. 15. The method for manufacturing a droplet discharge head according to claim 1, wherein said high-concentration P-type impurity is high-concentration boron. 16. The method for manufacturing a droplet discharge head according to claim 1, wherein in the polishing step, polishing is performed by a chemical mechanical polishing method using an aqueous solution having a hydroxyl group in a slurry liquid. A method for manufacturing a droplet discharge head, comprising: 17. The method for manufacturing a droplet discharge head according to claim 1, wherein the polishing step is polished by a spin etching method. 18. A nozzle for discharging droplets, a liquid chamber to which the nozzle communicates, a vibration plate forming a wall surface of the liquid chamber, and a displacement of the vibration plate to cause droplets to be discharged from the nozzle. In the droplet discharge head for discharging, both the first substrate provided with the vibration plate and the second substrate provided with the electrodes are made of a silicon substrate, and the first and second substrates are polished by at least one of them. A droplet discharge head, which is directly bonded with the surface as a bonding surface. 19. The droplet discharge head according to claim 18, wherein an insulating film having a polished surface is formed on a surface of the diaphragm facing the electrode. 20. The droplet discharge head according to claim 18, wherein the diaphragm is formed of a high-concentration P-type impurity silicon layer. 21. The droplet discharge head according to claim 18, wherein a surface roughness of the polished surface does not exceed Ra = 0.5 nm. . 22. A nozzle for discharging droplets, a liquid chamber to which the nozzle communicates, a vibration plate forming a wall surface of the liquid chamber, and a droplet being displaced from the nozzle by displacing and deforming the vibration plate. In the droplet discharge head to be discharged, at least a first substrate provided with the vibration plate and a second substrate provided with an electrode have a laminated structure in which the first substrate is formed of a silicon substrate and is polished. A droplet discharge head having a P-type impurity diffusion layer, wherein an insulating film formed on a polished surface of the P-type impurity diffusion layer is provided on a surface of the diaphragm facing the electrode. 23. The droplet discharge head according to claim 22, wherein at least the insulating film at the joint with the second substrate is removed. 24. The droplet discharge head according to claim 22, wherein the insulating film is a thermal oxide film. 25. The droplet discharge head according to claim 22, wherein the surface roughness of the insulating film is R.
A droplet discharge head, wherein a does not exceed 0.5 nm.