JP2001001515A - Method for machining silicon basic body, ink jet head employing silicon basic body and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrostatic ink jet head in which a common liquid chamber and ink channels having high sealing performance can be formed and mountability is enhanced by making possible to supply ink from the rear side of head. SOLUTION: A silicon substrate 1 and a thermally oxidized silicon substrate 2 are bonded directly under a low temperature of 5000-1000 deg.C (Fig. (A)) and then a mask layer 36 for wet etching is formed (Fig. (B)). The mask layer is then patterned on the side of the silicon substrate 2 previously applied with a thermal oxidation film 3 and through holes 52 are opened in the silicon substrate 2 with high concentration alkaline liquid of KOH, for example, (Fig. (C)). Since the thermal oxidation film 3 serving as the end point of the through holes 52 is the interface of thermal oxidation, high sealing performance is ensured and side etching is blocked. Subsequently, a through hole pattern 12 is opened in the silicon substrate 1 with high concentration alkaline liquid of KOH, for example, (Fig. (D)). Finally, the oxide film is removed by wet etching with hydrofluoric acid thus obtaining through holes (Fig. (E)).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet head suitable for use in an ink-jet printer or the like which performs recording by ejecting ink onto paper, and more specifically, a diaphragm provided in an ink liquid chamber is electrostatically charged. The present invention relates to an inkjet head that performs ink ejection by deforming with force, a method for manufacturing the same, and a method for manufacturing a silicon substrate suitable for the inkjet head.

[0002]

2. Description of the Related Art The most important features of an ink jet head printer are that it is smaller and less expensive than a recording device for electrophotography, etc., is excellent in personalization, and has been recognized as the most familiar recording device in recent years. And spread rapidly. There are two types of printing methods for inkjet printers: a continuous method that deflects ink jets that are always ejected to determine whether or not recording is performed, and an on-demand method that ejects ink only when recording is desired. Is the mainstream. The present invention relates to an ink-jet head, and can be used in both of the above-described methods. However, since each bit for ink ejection can be constituted by an individual electrode pair, it is naturally advantageous to use an on-demand method.

[0003] Typical types of ink jet heads include a thermal head (bubble head), a piezoelectric head, and an electrostatic head. In the thermal head, an individual heater is provided for each bit for ejecting ink. The individual heater instantly boiles the ink, and ejects the ink by the pressure of bubbles generated at that time. A piezoelectric head literally uses a piezoelectric body. A piezoelectric head is used to eject ink by applying a displacement in the thickness direction of the piezoelectric body as it is or through a diaphragm to an ink pressure chamber. There is a method in which a diaphragm is bent using (surface bending) to eject ink. The electrostatic head performs ink ejection by bending the vibration plate using electrostatic attraction. Although the thermal head and the piezoelectric head have already been put into practical use in mass production, it is necessary to individually incorporate a heater element and a piezoelectric element into each bit. In the way. On the other hand, an electrostatic head is expected as a next-generation device capable of achieving the highest density by using fine processing technology of a semiconductor or a micromachine.

In recent years, the image quality of an ink jet head printer has been recognized as having a quality equal to or higher than that of an electrophotograph, and a high-speed alternative to a recording apparatus such as an electrophotograph is required. I was like. Accordingly, there is an increasing demand for a line type head in which printing / recording is only required in the sub-scanning direction, and accordingly, a technique for easily and inexpensively line mounting an ink jet head has become an important issue.

Regarding the mounting of the head, it is important to mount not only the electrodes but also the ink supply. In the type of shuttle type head for a personal user who is less frequently used, there are many cases where the head is mounted on an ink cartridge and is disposable. However, in the case of a line type head conceived for general shared use in offices in the future, the head cost will increase, and the stationary type will be the mainstream. Therefore, it is also an important issue to make the head configuration easy to mount the ink supply port. A representative example of the electrostatic head system is disclosed in Japanese Patent Application Laid-Open No. H5-50601.
JP, JP-A-5-57887, JP-A-6-71
No. 882, for example.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made in consideration of the above-described circumstances. An ink-jet head using a silicon substrate, more specifically, a solid vibration substrate is deformed using electrostatic attraction ( A common liquid chamber (common ink chamber) and ink flow path (ink pressurizing chamber) having high sealability can be formed in an electrostatic ink jet head that ejects ink by bending the surface (surface bend), and the head can be formed from the back of the head. An object of the present invention is to provide a highly reliable and low-cost ink jet head which enables ink supply and facilitates mounting.

[0007]

According to the present invention, a silicon substrate on which a thermal oxide film is formed in advance and a silicon substrate on which a thermal oxide film is not formed are bonded to a silicon substrate bonded via the thermal oxide film. A method of processing a silicon substrate in which a through hole is formed by opening the silicon substrate by wet etching from both sides, wherein the silicon substrate is 500 to
In the method of processing a silicon substrate in the case where the silicon substrate is formed by thermal baking at a low temperature of about 1000 ° C., a silicon substrate on which a thermal oxide film has been formed before the bonding, The method is characterized in that the through-hole is formed first, and when the through-hole is formed in a silicon substrate directly joined to two silicon substrates at a temperature of about 500 to 1000 ° C., the sealing property of the joined portion and the liquid contact It does not impair the sex.

According to the first aspect of the present invention, 500 to 100
When a through-hole is made in a silicon substrate in which two silicon substrates are directly joined at a temperature of about 0 ° C., and when a through-hole / opening on one of the substrates is used as a common liquid chamber (common ink chamber), the surface thereof is used. Must be sealed in a later step. The invention of claim 2 is the invention of claim 1 as described above,
In a method of processing a silicon base, wherein one or a plurality of through-holes are formed in an opening region on one silicon substrate side of the silicon base from the other silicon substrate, the silicon base is sandwiched between the two silicon substrates. The oxide film is removed from the other substrate side by dry etching, so that not only the surface of the substrate is not damaged but also etching can be performed without a mask.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet head which is currently being developed and prototyped uses a silicon substrate in which a silicon substrate is bonded (bonded) by wafer-to-wafer. Specifically, a silicon substrate (hereinafter referred to as a silicon substrate B) on which individual electrodes for individually driving each bit are formed, and an individual diaphragm and an individual pressurized liquid chamber (ink pressurized chamber) ) (Hereinafter referred to as silicon substrate A)
) To form an electrostatic actuator portion.

[0010] The reason for bonding by wafer-to-wafer is to avoid individual assembly and to improve yield and reduce cost. Silicon substrate A and silicon substrate B
Wafer-to-wafer bonding is based on the silicon direct bonding (Si-Direct-bond) method used to form SOI substrates.
ing). In the case of an electrostatic head, the distance between the individual electrodes and the diaphragm (hereinafter, referred to as gap length) is as small as about 1 μm or less. Are suitable. For example, in the method using an adhesive, it is difficult to control the gap because an adhesive layer of at least a micron order is required, and the adhesive is applied thinly and uniformly on the entire surface of the wafer,
This is because it is very difficult to uniformly press-bond without causing air voids.

Also, the bonding method called direct bonding is
It is used because the gap length can be controlled precisely and the throughput is good. However, unlike the SOI substrate, the bonding interface does not need to be dense and uniform at the atomic level. In this case, it is necessary that there is no large void (gap) at the bonding interface that changes the gap length, that the bonding interface has sufficient strength so that it does not separate during the process (for example, dicing when forming into chips), and that the printer is driven. Is strong enough to withstand the shock of vibration and human error.

In a normal silicon direct bonding process, 1
The reason why thermal baking at a high temperature of 000 to 1200 ° C. (generally performed in a mixed atmosphere of oxygen and nitrogen) is required is not only bonding strength but also void-free (air gap between bonding substrates). Is to prevent the occurrence of). It is generally well known that void generation increases rapidly at a low temperature of about 1000 ° C. or lower.

Although the generation of voids as described above is a problem even in the case of using it for manufacturing an electrostatic ink jet head, the head according to the present invention has a gap formed on the silicon substrate B side as described above. This serves as a buffer so that voids are less likely to occur. In detail, void-free at low temperatures has been realized by devising and optimizing the dimensions of the gap pattern (including the size of the adhesive margin at the junction, the aperture ratio, etc.), the uniformity of the substrate surface, and the surface treatment method. I have. Since this point is outside the scope of the present invention, further detailed description is omitted, but until now, void-free bonding at a low temperature of at least about 500 ° C. has been possible. In this case, although the bonding strength is slightly lower than that of the SOI substrate, it has been confirmed by various strength tests that the ink jet head has sufficient bonding strength.

In the above, a case has been described in which a gap and individual electrodes are provided on the silicon substrate B side and the diaphragm on the silicon substrate A side is a common electrode (reference electrode).
The gap may be formed on the diaphragm side, the individual electrodes may be provided on the diaphragm side, and the common electrode may be formed on the silicon substrate B,
It is not limited to this.

The present invention, as described above,
The present invention relates to a method of forming a through passage in a silicon substrate bonded to silicon by direct bonding at a low temperature of 0 ° C., that is, a substrate of an ink jet head, and an effect obtained by the method. Hereinafter, the configuration and operation of the embodiment of the present invention will be described.

FIG. 1 and FIG. 2 are diagrams schematically showing an embodiment of the invention described in claim 1 of the present invention.
FIG. 2 shows a second embodiment. Thus, Example 1 shown in FIG. 1 is a case where the thermal oxide film 3 is formed on the silicon substrate B (2 in the figure), and Example 2 shown in FIG. In FIG. 1, 1) shows a case where a thermal oxide film 3 is formed. In the second embodiment shown in FIG. 2, the etching of the silicon substrates 1 and 2 is different from that of the first embodiment shown in FIG. Since only the order is changed,
The embodiment of FIG. 1 will be described, and the description of FIG. 2 will be omitted.

First, the silicon substrate 1 and the thermally oxidized silicon substrate 2 are directly bonded at a low temperature of 500 to 1000 ° C. (FIG. 1A), and then a wet etching mask layer 36 is formed (FIG. 1A). 1 (B)). In this embodiment, the best LP-CVD nitride film is used as the mask layer 36, but a thermal oxide film, tantalum pentoxide, or the like may be used, and the present invention is not limited to this.

Next, the mask layer 36 on the side of the silicon substrate 2 on which the thermal oxide film 3 has been previously formed is patterned by a known photolithography technique and etching technique, and is penetrated into the silicon substrate 2 with a high-concentration alkaline solution such as KOH. Is opened (FIG. 1 (C)). At this time, the thermal oxide film 3 is
Work as an endpoint for Since that portion is an interface of thermal oxidation, the sealing property is good and no side etch or the like is formed. Since the selection ratio is high, time management is sufficient.

Next, the mask layer 36 on the side of the silicon substrate 1 is patterned by a known photolithography technique and etching technique, and a pattern 12 for a through hole is opened in the silicon substrate 1 with a high-concentration alkaline solution such as KOH. FIG.
(D)). At this time, the oxide film in the through-hole portion on the silicon substrate 2 side is also slightly etched, but as described above, since it is an interface of thermal oxidation, the sealing property is good and no side etching or the like is formed. Next, if the oxide film 3 is wet-removed with hydrofluoric acid, a through hole is obtained (FIG. 1E).

The process (procedure) such as the above operation is performed by direct bonding at a temperature of about 500 to 1000 ° C., so that the bonding strength is slightly low and the bonding interface is microscopically one.
Since it is not as dense as that under a high temperature of 000 to 1200 ° C., as shown in FIG.
A side etch may enter the side, and in severe cases, the joint may peel off. As will be described later in the example of the third aspect of the present invention, it is important that the sealing property of this portion is important, and it is important that the interface is not damaged during the process. In the case where the bonding interface portion of the substrate is patterned as in the present head, it is necessary to pay attention to the bonding area (glue allowance), although the generation of voids is small.

FIGS. 1 and 2 show the simplest example of the first aspect. For example, when the silicon substrates 1 and 2 have the same substrate orientation and thickness, the silicon substrates are simultaneously subjected to opening etching. There is almost no problem. If it is necessary to reduce the thickness of the oxide film 3 on the bonding surface, the thermal oxide film 3 is formed on the substrate on the side where the penetration etching takes a long time,
It is good to adopt a method in which the thicker substrate is first etched partway, and the remaining portion is compensated by etching the other thinner substrate.

In this embodiment, the silicon substrate 1 has
A 625 μm thick Si (110) substrate was used, and a vertical opening was formed. A 600 μm Si (100) substrate was used as the silicon substrate 2 to form a 54.7 deg taper opening. In this case, the silicon substrate 2 has a lower etch rate, and
Since the plate thickness is large, the surface on which the thermal oxide film 3 is formed is
, The silicon substrate 2 side was etched first, and then the silicon substrate 1 side was etched.

FIGS. 4 and 5 schematically show an embodiment (Embodiment 3) according to claims 2 and 3, which is an improvement of Embodiment 2. FIG. FIG. 4 shows an example of the case where the oxide film at the junction is removed by wet etching using hydrofluoric acid or the case where the oxide film is removed from the silicon substrate 1 side by dry etching. FIG. 5 shows an example in which the oxide film at the junction is removed by dry etching from the silicon substrate 2 side (the surface with the smaller through hole). Note that FIG. 4C is the same as FIG.
5 (C) is a cross-sectional view taken along the line CC of FIG. 5 (A).

As will be described later in the fourth and fifth embodiments of the present invention, in the case of an ink jet head using the opening 12 on the silicon substrate 1 side as a common liquid chamber (common ink chamber), The surface must be sealed in a later step, so a mask for protecting the surface is required when dry etching is performed from the surface side, but a maskless mask is required when dry etching is performed from the silicon substrate 2 side. There is an advantage that it can be performed in. In the former case where a mask is used, the step of the opening 12 is several tens μm or more, so that ordinary resist work (photolithography technology) is difficult. Further, even when an individual mask is used instead, there is also a problem that the surface is damaged to a considerable extent due to plasma wraparound during dry etching. In addition, as shown in the example of FIG. 5, when the oxide film 3 is formed on the silicon substrate 1 side (when the oxide film 3 and the silicon substrate 2 are bonded surfaces), the bonding area (glue allowance) is reduced. )
Has the advantage that the sealing performance is also high.

In this embodiment, in order to obtain a vertical wall on the silicon substrate 1, the silicon substrate 1 is made of Si (110).
The substrate is made of silicon (100) of low cost for the silicon substrate 2.
A substrate is used. Since the openings 12 and the through holes 52 are formed by anisotropic etching, the side walls are all S-shaped.
It is formed on the i (111) plane (claim 3). Si (11
1) Since the surface is also a stop surface for etching, it has high alkali resistance and excellent liquid contact property (ink resistance). Therefore, only the surface of the joint (the interface of the silicon substrate) (10
0) surface, which is a surface with poor wettability. That is, as shown in FIG. 5, by leaving the oxide film 3 on the surface having poor liquid contact property, an ink liquid chamber / flow path excellent in liquid contact property can be formed.

FIG. 6 schematically shows an embodiment (Embodiment 4) according to claims 4 and 5, wherein FIG. 6 (A) is a plan view of a main part and FIG. 6 (B) is a plan view of FIG. In the figure, 1, 2 and 3 denote silicon substrates 1 and 2 and a thermal oxide film 3 similar to those in the above-described embodiment, 10 denotes a silicon diaphragm serving also as a common electrode, 11 Is a pressurized liquid chamber for ink ejection, 12 is a common liquid chamber, and 13 is a fluid resistance (the ink is supplied from the common liquid chamber 12 to the pressurized liquid 11 chamber when not pressurized, and the backflow of the ink is reduced when pressurized. , 21 is an individual electrode for driving the diaphragm, 22 is an individual electrode protective film, 31 is an electrostatic gap between the diaphragm and the individual electrode, and 52 is an ink supply path also serving as an ink supply port (the above-described through-hole). 4 is a nozzle plate for ejecting ink (also serves as a sealing lid for various liquid chambers), 4
1 is an injection nozzle.

By adopting the configuration shown in FIG. 6 and the manufacturing method described above, a series of head-to-wafer head forming processes becomes possible (a series of processes will be described later). From the surface (rear surface) opposite to the ink ejection port (nozzle) 41. Since the ink supply port 52 is provided on the back surface, die bonding at the time of electrode mounting or production of a line type head is easy. Also,
Since there is no ink supply port on the nozzle surface, wiping (removal of unnecessary ink on the nozzle surface and other cleaning)
This also facilitates installation of a reliability maintenance mechanism such as the above.

The example of FIG. 6 is an example in which each bit is arranged in a staggered manner on the left and right, and is not symmetrical. Also,
It should be added that the shapes and the like of the fluid resistance portion 13 and the various liquid chambers 11 and 12 are schematically drawn, and that the actual shapes are slightly different. FIG. 6 specifically explains the invention of claim 5, and the invention of claim 5 is a special case of the invention of claim 4. Although the detailed description of the general embodiment of claim 4 is omitted, the ink jet head is characterized in that the opening 12 is used as a common liquid chamber and the through hole 52 is used as an ink supply port. .

FIG. 7 schematically shows an embodiment (Embodiment 5) of the method for manufacturing an ink jet head according to claim 6, in which a part of the bonding surface side of the silicon substrate 1 is left, and the remaining part is vibrated in a solid state. It shows a process flow when used as a plate. In the case of the example shown in FIG. 7, a high-concentration boron layer 10 of about 1E19 to 5E20 / cm ³ is formed in advance on the bonding surface side of the silicon substrate 1 (FIG. 7).
(A)). The high-concentration boron layer has a low etching rate and serves as an etching end point. As in the first and second embodiments, the silicon substrate 1 on which the boron layer 10 is formed and the silicon substrate 2 on which the thermal oxide film 3 is formed are directly bonded, and then a wet etching mask layer 36 is formed.
(B)), the mask layer 36 on the side of the silicon substrate 2 is patterned, and a through hole 52 is opened in the silicon substrate 21 (FIG. 7C). FIG. 7D shows a state where the etching is stopped at the high-concentration boron layer 10. The remaining silicon substrate 10 (boron layer 10) is used as a solid vibration plate. Next, FIG. 7E shows that the remaining silicon was removed by dry etching from the silicon substrate 1 side, and FIG. 8 (Claim 6) shows that the remaining silicon was removed by dry etching from the silicon substrate 2 (back surface) side. is there. Here, in the case of FIG. 7 (E), a mask is required so that the diaphragm in the pressurized liquid chamber is not removed, but in the case of FIG. 8, it can be performed without a mask.

In the former case using a mask (FIG. 7 (E)), a normal resist work (photoengraving technique) is difficult because the step of the opening 12 is on the order of several 100 μm. Further, even when a solid mask is used instead, there is also a problem that the surface of the substrate 1 is damaged to a considerable extent due to plasma wraparound during dry etching. In addition, as in the embodiment of FIG. 7, when the thermal oxide film 3 is formed on the silicon substrate 2 side (when the oxide film 3 and the remaining silicon substrate 10 are at the bonding interface), the bonding area is increased. There is also an advantage that the sealing performance is high because the (glue allowance) increases.

In the above description, the high-concentration boron layer 10 is taken as an example of a method for leaving a part of the silicon substrate 1 on the bonding surface. However, the method may be performed by controlling the time without forming the high-concentration boron layer. Alternatively, instead of the silicon substrate 1, SO
An I wafer may be used. SOI wafers are costly but easier to process.

FIGS. 9A and 9B schematically show an embodiment (Embodiment 6) of the seventh aspect of the present invention. FIGS. 9A and 9B show FIGS. 1 and 2 and FIGS. 9 (C) shows the state after oxidation in each case of FIG. By performing the oxidizing process 62 after penetrating the silicon substrate 1 and the silicon substrate 2 in this manner, a protective layer can be easily formed on the front surface of the ink jet head before liquid contact, and the silicon walls of various liquid chambers and flow paths can be formed. It is needless to say that the liquid contact property is improved, but it is particularly effective in improving the sealing property of the joint surface.

FIG. 10 shows a series of wafer forming process flows of wafer-to-wafer in the present invention. Details of the effects and processes of each part are as described above, and the details are omitted. 10A to FIG.
In (D), the left side (a ₁ -d ₁ ) is a plan view, and the right side (a ₂ -d ₂ ) is a ₁ -a in the left side figure (a ₁ -d ₁ ).
₂ , b ₁ -b ₂ , c ₁ -c ₂ , and d ₁ -d ₂ are sectional views.

FIG. 10A shows a state before the bonding, in which a thermal oxide film 3 for bonding, an individual electrode 21 and an individual electrode protection film 22 are formed on the silicon substrate 2. Further, a high-concentration boron layer 10 is formed on the silicon substrate 1. Here, the method of forming the thermal oxide film 3, the electrostatic gap 31, the individual electrodes 21, and the protective film 22 and their procedures are not described because they depart from the invention of the present invention, but the illustrated example is merely an example. Yes, the present invention is not limited to this.
In addition, gaps, electrodes, and the like may be provided on the silicon substrate 1 side, and are not limited to the illustrated example. Further, although a high-concentration boron layer is formed as the diaphragm stop layer, the present invention is not limited to this, as long as the diaphragm portion 10 can be satisfactorily left.

FIG. 10B shows that after bonding, a mask layer 36 is formed, and the mask layer on the silicon substrate 2 side is patterned to form a through hole 52.

FIG. 10C shows that the mask layer on the silicon substrate 1 side is patterned to form openings such as the common liquid chamber 12, the pressurized liquid chamber 11, the fluid resistance section 13, and the like. . In this embodiment, the opening is formed by one patterning and one anisotropic etching.

FIG. 10D shows that the oxide film 3 in the portion of the through hole 52 on the silicon substrate 2 side is removed by wet etching or from the silicon substrate 2 side by dry etching without using a mask. 10 shows that the silicon wafer 10 was removed from the silicon substrate 2 side by dry etching without using a mask, the surface to be in contact with the liquid was oxidized, and the remaining silicon 10 in the electrode pad part 20 was removed by dry etching. . Here, the oxidation treatment may be performed after the opening of the electrode pad portion 20, but in this case, it is better to keep the oxidation light.

[0038]

(Effect of Claim 1) The invention of Claim 1 is
A silicon substrate on which a thermal oxide film is formed in advance and a silicon substrate on which a thermal oxide film is not formed are opened to the silicon substrate bonded via the thermal oxide film by wet etching from both sides. A method of processing a silicon substrate, wherein the silicon substrate is bonded by thermal sintering at a low temperature of about 500 to 1000 ° C. A through-hole is formed before the other silicon substrate on the silicon substrate on which the thermal oxide film has been previously formed. In this case, two silicon substrates are formed at a temperature of about 500 to 1000 ° C. When a through hole is made in the silicon substrate directly bonded to the
Does not impair wettability.

(Effect of Claim 2) 500 to 1000 ° C.
When a through-hole is made in a silicon substrate directly joined to two silicon substrates at a temperature of about the same, when the through-hole / opening on one of the substrates is used as a common liquid chamber (common ink chamber), the surface thereof is placed behind. According to the invention of claim 2, the oxide film sandwiched between the two silicon substrates is removed from the other substrate side by dry etching. In addition to not damaging the mask, etching can be performed without a mask.
Therefore, the area of the joint area (glue allowance) is large, and the sealing property and strength are high. Furthermore, the liquid contact property is high because the oxide film remains on the silicon portion having low liquid contact property.

(Effect of Claim 3) According to the invention of Claim 3, since the side walls are all formed of the Si (111) surface, the alkali resistance is high and the liquid contact property (ink resistance) is excellent.

(Effects of Claims 4 and 5) According to the inventions of Claims 4 and 5, since the ink supply port can be taken from the surface (back surface) opposite to the ink ejection surface, the electrode mounting and the Die bonding at the time of manufacturing a line type head is easy. Also,
Since there is no ink supply port on the nozzle surface, wiping (removal of unnecessary ink on the nozzle surface and other cleaning)
This also facilitates installation of a reliability maintenance mechanism such as the above.

(Effect of Claim 6) According to the invention of Claim 6, the portion corresponding to the solid diaphragm in the common liquid chamber region is removed from the back surface side of the other silicon substrate by dry etching. Therefore, through etching can be performed without using a mask without damaging the surface serving as the liquid chamber sealing surface (without removing the diaphragm in the pressurized liquid chamber, maskless etching can be performed only on the through portion).
There are advantages such as. Sealing and strength are high due to the large area of bonding (glue allowance).

(Effect of Claim 7) According to the invention of claim 7, since the oxidation treatment is performed after penetrating between the one silicon substrate and the other silicon substrate,
A protective layer can be easily formed on the entire surface of the ink jet head that comes in contact with the liquid, and it is needless to say that the liquid contact of the silicon walls of the various liquid chambers and the flow paths is improved. Effective for improvement.

[Brief description of the drawings]

FIG. 1 is a view schematically showing one embodiment of the first aspect of the present invention.

FIG. 2 is a diagram schematically showing another embodiment of the first aspect of the present invention.

FIG. 3 is a view showing an example in which a side etch is formed in the silicon substrate 1 in the embodiment shown in FIGS. 1 and 2;

FIG. 4 is a diagram showing an example of a case where an oxide film at a junction is removed by wet etching using hydrofluoric acid or a case where the oxide film is removed by dry etching from the silicon substrate 1 side.

FIG. 5 is a diagram showing an example in which an oxide film at a bonding portion is removed by dry etching from the silicon substrate 2 side (the surface with a smaller through hole);

FIG. 6 is a diagram schematically showing an embodiment (Embodiment 4) of Claims 4 and 5;

FIG. 7 is a view schematically showing an embodiment (Embodiment 5) of claim 6;

FIG. 8 is a diagram showing an example of a case where the embodiment shown in FIG. 7 is performed without a mask.

FIG. 9 is a diagram schematically showing an embodiment (Embodiment 6) of claim 7;

FIG. 10 is a view showing a series of wafer-to-wafer head forming process flows in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Silicon substrate, 3 ... Thermal oxide film,
10 high concentration boron layer (vibration plate), 11 pressurized liquid chamber, 1
2 ... through-hole pattern (opening, common liquid chamber), 13 fluid resistance part, 20 ... electrode pad part, 21 ... individual electrode for driving diaphragm, 22 ... individual electrode protective film, 31 ... gap, 36
... mask layer, 40 ... penetrating part, 41 ... injection nozzle, 52 ...
Through-hole (ink supply port), 62: oxide film.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C057 AF65 AF93 AG14 AG54 AP02 AP13 AP14 AP32 AP33 AP34 AQ02 BA04 BA15 5F043 AA02 AA31 BB02 BB22 DD01 DD15 DD30 FF06 GG10

Claims (7)

[Claims] 1. A silicon substrate on which a thermal oxide film is formed in advance and a silicon substrate on which a thermal oxide film is not formed are bonded to a silicon substrate bonded via the thermal oxide film from both sides. A method for processing a silicon substrate, wherein a through hole is formed by opening by wet etching,
In the method for processing a silicon substrate, in which the silicon substrate is bonded and formed by thermal firing at a low temperature of about 500 to 1000 ° C., the silicon substrate on the side on which a thermal oxide film is formed in advance before the bonding is formed. Forming a through hole before forming another silicon substrate. 2. The method for processing a silicon substrate according to claim 1, wherein one or a plurality of through holes are formed in the opening region of the silicon substrate on one silicon substrate side from the other silicon substrate side. A silicon substrate processing method, wherein an oxide film sandwiched between the two silicon substrates is removed from the other substrate side by dry etching. 3. A method for processing a silicon substrate, comprising: forming a through hole by opening silicon from both sides by anisotropic etching on a silicon substrate to which two silicon substrates are joined via a thermal oxide film. A method for processing a silicon substrate, wherein an end point of the anisotropic etching is the thermal oxide film or the Si (111) plane. 4. An electrostatic ink-jet head using the silicon substrate according to claim 1, wherein said ink-jet head is provided in an opening region of said silicon substrate on one silicon substrate side. A silicon substrate having one or a plurality of through holes formed therethrough from one silicon substrate side, wherein the opening area on the one silicon substrate side is a common liquid chamber (common ink chamber), and the other silicon substrate is The through-hole on the side is used as an ink supply port from the outside, a pressurized liquid chamber and a vibration plate are formed on the one silicon substrate, and individual electrodes for actuators are formed on the other silicon substrate. Inkjet head. 5. The electrostatic ink jet head according to claim 4, wherein an ink ejection surface is on the one silicon substrate side, and an ink supply port is a surface of the other silicon substrate opposite to the ink ejection surface. (An underside) an ink jet head. 6. The method for manufacturing an ink jet head according to claim 4, wherein a part of the one silicon substrate on a bonding surface side is left and used as the diaphragm. A method for manufacturing an ink jet head, wherein a portion corresponding to the vibration plate in a common liquid chamber region is removed from a back surface side of the other silicon substrate by dry etching. 7. The method for manufacturing an ink jet head according to claim 6, wherein an oxidation treatment is performed after penetrating between the one silicon substrate and the other silicon substrate.