JP2007196414A - Method for manufacturing droplet ejection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a droplet ejection head capable of preventing cracking in processing of a substrate to improve the yield by enhancing the strength of a portion having a large area such as an electrode extraction portion and improving the processing accuracy without being limited by a shape, a size or the like of a jig when the electrode extraction portion is opened by dry-etching. <P>SOLUTION: In the method for manufacturing the droplet ejection head, a boron diffusion layer 102a is selectively formed to be thick on a portion of a bonding face side of a silicon substrate 100 to be bonded to an electrode substrate 2 corresponding to the electrode extraction portion 26. After the silicon substrate is bonded to the electrode substrate to be a thin plate, a recessed section 26c is formed on the silicon substrate by applying wet-etching thereto. An SiO<SB>2</SB>film 105 is formed on the silicon substrate by using a mask member having an opening at a portion except the electrode extraction portion, and then the bottom of the recessed section of the electrode extraction portion on which the SiO<SB>2</SB>film is not formed, is removed by the dry-etching to make the opening. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a droplet discharge head such as an inkjet head.

As a droplet discharge head for discharging droplets, for example, an inkjet head mounted on an inkjet recording apparatus is known. Ink jet heads generally include a nozzle substrate in which a plurality of nozzle holes for ejecting ink droplets are formed, and ink such as a discharge chamber and a reservoir that are joined to the nozzle substrate and communicate with the nozzle holes. And a cavity substrate on which a flow path is formed, and an ink droplet is ejected from a selected nozzle hole by applying pressure to the ejection chamber by an actuator.
In such an ink jet recording apparatus, in recent years, the number of nozzles has been increased in order to cope with high-speed printing, and a minute actuator has been demanded from the demand for higher resolution.

  When the actuator density is increased, the thickness of the partition wall constituting the discharge chamber is reduced in accordance with the increase in density, so that the rigidity of the partition wall is reduced. As a result, the nozzle holes that are not driven are affected by the adjacent dots. In other words, ink droplets leak out, so-called crosstalk is likely to occur. In order to suppress the occurrence of this crosstalk, if the diaphragm made up of the partition wall of the discharge chamber and its bottom wall is formed after the thickness of the silicon substrate is reduced from the beginning by a conventional method, the handling of the cavity substrate is now performed. There is a problem that the yield is extremely lowered due to cracking or chipping of the cavity substrate.

  In response to this problem, for example, Patent Document 1 forms a diaphragm and a partition wall for a discharge chamber after bonding a silicon substrate serving as a cavity substrate and an electrode substrate including individual electrodes, and then reducing the thickness of the silicon substrate. Thus, the yield is prevented from decreasing, the rigidity of the partition walls is increased, and the occurrence of crosstalk is suppressed.

  Further, for example, Patent Document 2 discloses an opening method of an electrode extraction portion for wiring to individual individual electrodes. Here, the diaphragm is formed to a desired thickness, and at the same time, the electrode extraction portion is used as a vibration plate. Etch to the same thickness. Thereafter, the silicon remaining in the electrode extraction portion is opened by dry etching in a state where the etching metal mask is overlapped.

Japanese Patent Laid-Open No. 11-993 JP 2001-63072 A

  In the processes of Patent Document 1 and Patent Document 2, a thin film portion made of a boron diffusion layer having a thickness equivalent to that of the diaphragm is formed on the portion of the silicon substrate corresponding to the electrode extraction portion for wiring to the individual electrode. Therefore, the thin film portion is removed by dry etching using a metal mask, and the electrode extraction portion is opened. However, if a thin film part with a thickness equivalent to that of the diaphragm is formed on a part having a large area such as an electrode extraction part, the strength of the thin film part is reduced, so it may break during substrate processing, resulting in a decrease in yield. Was invited. In addition, when a metal mask is used for opening the electrode extraction portion, it is necessary to improve the adhesion between the substrate and the metal mask in order to prevent the etching gas from flowing around during dry etching and improve the processing accuracy. . In order to improve the adhesion, there is a method of sandwiching the substrate and the metal mask with a dedicated jig. In this case, there are restrictions on the shape and size of the jig that can be set in the etching chamber. In addition, there is a problem that the structure of the jig becomes complicated.

  In the present invention, by increasing the strength of a portion having a large area such as an electrode extraction portion, it is possible to prevent cracking during substrate processing and improve the yield, and further, the electrode extraction portion is opened by dry etching. It is an object of the present invention to provide a method of manufacturing a droplet discharge head that can improve processing accuracy without being restricted by the shape, size, etc. of a jig.

In order to solve the above problems, a first method for manufacturing a droplet discharge head according to the present invention includes a step of bonding a silicon substrate to an electrode substrate on which individual electrodes have been formed in advance, and a step of processing the silicon substrate into a thin plate. And a method of manufacturing a droplet discharge head, comprising: forming a plurality of recesses including discharge chambers on the thinned silicon substrate; and forming an electrode extraction portion for wiring to each of the individual electrodes. In
A step of selectively and thickly forming a boron diffusion layer in a portion corresponding to the electrode extraction portion on the bonding surface side of the silicon substrate before bonding;
After the silicon substrate is bonded to the electrode substrate and thinned, the silicon substrate is wet etched from the surface until the boron diffusion layer is reached, and a recess is formed in the electrode extraction portion;
Forming a SiO ₂ film on the silicon substrate using a mask member having an opening other than the electrode extraction part;
Removing and opening the bottom of the concave portion of the electrode extraction portion where the SiO ₂ film is not formed by dry etching; and
It is characterized by having.

In the present invention, a boron diffusion layer is selectively formed thick in a portion corresponding to the electrode lead-out portion on the bonding surface side of the silicon substrate before bonding, thereby forming a discharge chamber or a reservoir in the silicon substrate after bonding with the electrode substrate. When wet etching is performed to form a recess, the bottom of the electrode lead-out portion having a large area is a thick boron diffusion layer, so that it is not cracked, so that the yield can be improved.
Moreover, those using a mask member having an opening other than the electrode extraction portion of the SiO ₂ film formed on the silicon substrate, the bottom of the recess of the electrode extraction portion of SiO ₂ film is not formed is removed by dry etching to open Therefore, there is almost no wraparound of the etching gas, and processing with a good shape and high processing accuracy can be realized.
Furthermore, when the bottom of the electrode extraction part is opened by dry etching, the SiO ₂ film serves as a protective mask for the etching gas, so that the shape of the recess that becomes the discharge chamber and the reservoir is not impaired and can be processed with high accuracy. In addition, since the bonded substrate can be set directly in the etching chamber, a jig is not required as in the prior art, and therefore the processing accuracy can be improved without being restricted by the shape, size, etc. of the jig.

The second manufacturing method of the droplet discharge head according to the present invention includes a step of bonding a silicon substrate to an electrode substrate on which individual electrodes are formed in advance, a step of processing the silicon substrate into a thin plate, and the thinning In a method for manufacturing a droplet discharge head, the method includes: forming a plurality of recesses including discharge chambers in the silicon substrate formed; and forming an electrode extraction portion for wiring to each of the individual electrodes.
A step of selectively and thickly forming a boron diffusion layer in a portion corresponding to the electrode extraction portion on the bonding surface side of the silicon substrate before bonding;
After the silicon substrate is bonded to the electrode substrate and thinned, the silicon substrate is wet etched from the surface until the boron diffusion layer is reached, and a recess is formed in the electrode extraction portion;
Forming a SiO ₂ film over the entire surface of the silicon substrate;
Patterning the SiO ₂ film on the bottom surface of the recess of the electrode lead-out portion by photolithography;
Removing and opening the bottom of the recess of the electrode lead-out portion where the SiO ₂ film is opened by dry etching; and
It is characterized by having.

In the second manufacturing method of the present invention, an SiO ₂ film serving as a protective mask for the etching gas is formed on the entire surface of the silicon substrate, and then only the electrode extraction part is patterned and opened by photolithography. This second manufacturing method also has the same effect as the first manufacturing method.

  In the present invention, the step of forming the boron diffusion layer may include forming a thermal oxide film or a TEOS film on the bonding surface side of the silicon substrate, and a portion of the thermal oxide film or TEOS film corresponding to the electrode extraction portion. Then, boron is diffused through the opening and the thermal oxide film or TEOS film.

  When diffusing high-concentration boron on the bonding surface side of the silicon substrate, the thermal oxide film or TEOS film has an action of suppressing the diffusion of boron and has a smaller diffusion constant than silicon, and therefore corresponds to the electrode lead-out portion. The boron diffusion layer can be formed thick in the portion through the opening of the thermal oxide film or the TEOS film, and the boron diffusion layer can be formed thin in the portion corresponding to the other discharge chamber or the like. In addition, since a thin boron diffusion layer in each part can be formed at the same time, the boron diffusion process can be completed once, so that the process can be simplified and the manufacturing cost can be reduced.

Therefore, the bottom of the discharge chamber is formed by a thin boron diffusion layer.
Thereby, the thickness of the diaphragm formed at the bottom of the discharge chamber can be formed into a thin film with high thickness accuracy by an etching stop action during wet etching.

The silicon substrate is preferably a silicon substrate having a plane orientation of (110).
The silicon substrate having a (110) surface orientation can form the wall surface of the recess perpendicular to the substrate surface during anisotropic wet etching, so that the nozzle density can be increased.

  Hereinafter, embodiments of a droplet discharge head manufactured by the manufacturing method of the present invention will be described with reference to the drawings. Here, as an example of a droplet discharge head, a face discharge type electrostatically driven inkjet head that discharges ink droplets from nozzle holes provided on the surface of a nozzle substrate will be described with reference to FIG. Note that the present invention is not limited to the structure and shape shown in the following drawings, and is also applicable to an edge discharge type liquid droplet discharge head that discharges liquid droplets from nozzle holes provided at the end of the substrate. The same can be applied.

  FIG. 1 is a schematic configuration diagram of an ink jet head according to the present embodiment, FIG. 1A is a back view of the ink jet head, and FIG. 1B is a cross section taken along line bb of FIG. FIG. 1C is a longitudinal sectional view, and FIG. 1C is a transverse sectional view of the ink-jet head showing a cc section in FIG.

An ink jet head (an example of a droplet discharge head) 10 according to the present embodiment has a configuration in which a silicon cavity substrate 1 is sandwiched and a glass electrode substrate 2 and a silicon nozzle substrate 3 are stacked on top and bottom thereof. ing. A large number of nozzle holes 31 are opened on the surface of the nozzle substrate 3. A discharge chamber 11 communicating with each nozzle hole 31 is defined between the nozzle substrate 3 and the cavity substrate 1, and each discharge chamber 11 communicates with a common reservoir 13 via an orifice 32. . Ink is supplied to the reservoir 13 from the outside through an ink supply hole 23 penetrating the electrode substrate 2. Moreover, the bottom surface part (upper part of FIG.1 (b)) of each discharge chamber 11 is the diaphragm 12 which can vibrate in an out-of-plane direction.
The discharge chamber 11, the diaphragm 12 and the reservoir 13 at the bottom of the discharge chamber 11 are configured by forming a recess in the silicon substrate by anisotropic wet etching.

The cavity substrate 1 is bonded to the electrode substrate 2 via an insulating film 14 made of a SiO ₂ film or a TEOS (Tetraethylorthosilicate Tetraethoxysilane) film. This insulating film 14 is provided in order to prevent dielectric breakdown and short circuit when the inkjet head 10 is driven. A recess 21 having an elongated groove shape and a constant depth is formed at a position facing each diaphragm 12 on the joint surface of the electrode substrate 2 with the cavity substrate 1. An individual electrode 22 made of, for example, ITO (Indium Tin Oxide) is formed on the bottom surface of the recess 21, and the individual electrode 22 faces the diaphragm 12 with a certain gap (gap G). Further, the end of the gap G is hermetically sealed with a sealing material 24 made of an epoxy adhesive or the like so that foreign matter, moisture, or the like does not enter the gap G.

  The individual electrode 22 is formed so as to extend to the rear end surface 25 of the electrode substrate 2 along the bottom surface of the recess 21, and the rear end portion (terminal portion 22 a) serves as an electrode lead-out portion 26 for external wiring connection. . That is, as shown in FIG. 1B, in the electrode extraction part 26, a flexible wiring board (not shown) on which the driving means 4 made of a driver IC or the like is mounted is connected to the terminal part 22a of each individual electrode 22 and the cavity board 1. Are connected to a common electrode 15 provided in In this way, for each nozzle hole 31, a minute electrostatic actuator section is configured that includes the diaphragm 12 on the bottom surface of the discharge chamber 11 and the individual electrode 15 arranged to face the diaphragm 12 with a certain gap G interposed therebetween. ing.

The ink jet head 10 applies a voltage between the diaphragm 12 and the individual electrode 22 by the driving unit 4 to generate an electrostatic force, deforms the diaphragm 12 toward the individual electrode 22, and then applies the applied voltage. Ink droplets are ejected from the nozzle holes 31 by the pressure generated by the spring force of the diaphragm 12 generated when the ink is removed. Although not shown in FIG. 1, in this embodiment, the diaphragm 12 is composed of, for example, a high-concentration boron-doped layer. In order to form the diaphragm 12 having a desired thickness, a boron doped layer having the same thickness is formed. This is because, when anisotropic wet etching of silicon is performed with an alkaline aqueous solution, the etching rate becomes extremely small in a high concentration region (about 5 × 10 ¹⁹ atoms · cm ⁻³ or more) when boron is used as a dopant. Therefore, in the present embodiment, when the concave portion serving as the discharge chamber 11 and the concave portion serving as the reservoir 13 are formed by anisotropic wet etching, a so-called etching stop that utilizes the fact that the etching rate becomes extremely small when the boron doped layer is exposed. Using technology, the thickness of the diaphragm 12 and the volume of the discharge chamber 11 are formed with high accuracy.

  Next, the manufacturing method of the inkjet head 10 comprised as mentioned above is demonstrated based on FIG. 2 thru | or FIG. In addition, the values such as temperature, pressure, time, and thickness used in the following description are examples, and the present invention is not limited by these values.

First, a manufacturing process of an electrode substrate for use in manufacturing the inkjet head of the present invention will be described with reference to FIG.
First, a Cr / Au film 201 is formed by sputtering on the upper surface of a glass substrate 200 made of borosilicate glass having a thickness of 1 mm (surface to be bonded to a silicon substrate 100 described later) (FIG. 3A). Next, the Cr / Au film 201 is patterned into a shape corresponding to the recess 21 by photolithography, and a portion corresponding to the recess 21 is removed by etching (FIG. 3B). Then, using the Cr / Au film 201 as an etching mask, the glass substrate 200 is etched with a hydrofluoric acid aqueous solution to form a recess 21 having a depth of 0.2 μm (FIG. 3C). Thereafter, the Cr / Au film 201 is completely removed by etching (FIG. 3D), and an ITO film 202 is formed as an electrode material on the entire upper surface of the glass substrate 200 to a thickness of 0.1 μm by sputtering (FIG. 3). (E)). Next, the ITO film 202 is patterned by photolithography, and the ITO film 202 other than the portion that becomes the individual electrode 22 is removed by etching to form the individual electrode 22 on the bottom surface of the recess 21 (FIG. 3F). . Then, a hole is drilled in the glass substrate 200 with a diamond drill to form the ink supply hole 23 (FIG. 3G).
Thus, the electrode substrate 2 is manufactured. The electrode substrate 2 may not be made of glass, and a silicon substrate or other substrate material can be used.

Next, a manufacturing process of the silicon substrate 100 before bonding to the electrode substrate 2 manufactured as described above will be described with reference to FIG.
First, a silicon substrate 100 having a thickness of 525 μm is prepared by polishing one surface (lower surface) on the side to be bonded to the electrode substrate 2 (FIG. 3A). The silicon substrate 100 is preferably a silicon substrate having a plane orientation of (110). This is because when the recess such as the discharge chamber is formed by anisotropic wet etching, the wall surface of the recess can be formed perpendicular to the surface of the substrate, which is suitable for increasing the nozzle density. .

Next, SiO ₂ films 101a and 101b having a thickness of 0.25 μm are formed on the entire surface of the silicon substrate 100 (FIG. 3B). The SiO ₂ films 101a and 101b can be formed by setting the silicon substrate 100 in an oxidation furnace and performing thermal oxidation under conditions of an oxidation temperature of 1100 ° C., an oxidation time of 3 hours and 20 minutes in an oxygen atmosphere.

The SiO ₂ films 101a and 101b are used for limiting the diffusion action of boron with respect to silicon, and may be any film that suppresses the amount of boron diffusion with respect to silicon. In addition to the SiO ₂ film, the TEOS film But you can. Since the diffusion constant of the SiO ₂ film and the TEOS film is about 1/10 that of silicon, the mask effect is used to control the thickness of the boron diffusion amount for each region of the silicon substrate 100 as will be described later. can do. The TEOS film can be formed by plasma CVD (Chemical Vapor Deposition). The method for forming the SiO ₂ film or TEOS film is not particularly limited.

Next, a portion 26a of the SiO ₂ film 101a on the lower surface of the silicon substrate 100 corresponding to the electrode lead-out portion is patterned by photolithography, and the SiO ₂ film 101a on the lower surface of the substrate of this portion 26a is removed by etching to open (FIG. 3 (b)). The electrode lead-out part 26 (see FIG. 1) has the largest bottom area when the concave part corresponding to the electrode lead-out part 26 is formed when the concave part of each part that becomes a discharge chamber or the like is formed in the silicon substrate 100 by wet etching. An opening 26a is provided in the region corresponding to the recess by patterning the SiO ₂ film 101a. However, a portion other than the portion corresponding to the electrode extraction portion, for example, the reservoir portion can be targeted.

Next, boron at a high concentration (about 5 × 10 ¹⁹ atoms · cm ⁻³ or more) is diffused on the lower surface of the silicon substrate 100 through the SiO ₂ film 101a and the opening 26a to form a boron diffusion layer (FIG. 3). (C)). In the diffusion of boron, the silicon substrate and the diffusion source are set in the diffusion furnace so that the diffusion source mainly composed of B ₂ O ₃ faces the lower surface of the silicon substrate 100, the diffusion temperature is 1100 ° C., and the diffusion time is 15 hours. Under the conditions, boron is diffused at a high concentration on the lower surface of the silicon substrate 100 to form boron diffusion layers 102a and 102b. At this time, as shown in FIG. 3C, boron is diffused deeply into the portion (opening) 26a corresponding to the electrode extraction portion from which the SiO ₂ film 101a has been removed, for example, a thick diffusion layer 102a having a thickness of 3 μm. In other portions, the boron reaches the silicon substrate surface after diffusing the SiO ₂ film 101a having a low diffusion constant, so that boron is diffused shallowly, for example, a thin diffusion layer 102b having a thickness of 0.8 μm is formed. Is done.

Further, the boron diffusion method is not limited to the above-mentioned solid phase diffusion method, but a vapor phase diffusion method, an ion implantation method, or a method of spin coating a coating agent in which B ₂ O ₃ is dispersed in an organic solvent is used. May be.

Next, the SiO ₂ films 101a and 101b on the silicon substrate surface are all removed with a hydrofluoric acid aqueous solution (FIG. 3D). Although the surface of the boron diffusion layer boron compound is formed (not shown), in an oxygen and steam atmosphere, to oxidize 1 hour 30 minutes under conditions of 600 ° C., the etching can be B ₂ O ₃ It can be chemically changed to + SiO ₂ . Then, B ₂ O ₃ + SiO ₂ can be removed by etching by immersing the silicon substrate 100 in a hydrofluoric acid aqueous solution for 10 minutes.

Next, an insulating film 14 having a thickness of 100 nm made of a TEOS film is formed on the lower surface of the silicon substrate 100 by plasma CVD (FIG. 3E). The film formation conditions are a temperature of 360 ° C., a high frequency output of 250 W, a pressure of 66.7 Pa (0.5 Torr), a gas flow rate of TEOS flow rate of 100 cm ³ / min (100 sccm), and an oxygen flow rate of 1000 cm ³ / min (1000 sccm).

  As described above, the silicon substrate 100 before being bonded to the electrode substrate 2 described above, that is, the silicon substrate 100 that is the basis of the cavity substrate 1 of FIG. 1 is manufactured.

  Next, a first manufacturing method for manufacturing the ink jet head 10 using the silicon substrate 100 and the electrode substrate 2 will be described with reference to process cross-sectional views of FIGS.

FIG. 4A shows a silicon substrate 100 manufactured through the process of FIG. FIG. 4B shows the electrode substrate 2 manufactured through the process of FIG.
Then, as shown in FIG. 4C, the silicon substrate 100 and the electrode substrate 2 are anodic bonded through the insulating film 14. In anodic bonding, after the silicon substrate 100 and the electrode substrate 2 are heated to 360 ° C., a negative electrode is connected to the electrode substrate 2 and a positive electrode is connected to the silicon substrate 100, and a voltage of 800 V is applied and bonded.

  Next, the upper surface of the silicon substrate 100, that is, the surface opposite to the bonding surface, is ground with a grinder to a thickness of 150 μm. At this time, a trace of grinding so as to draw a parabola from the center remains on the surface of the silicon substrate 100, and the surface roughness (Rmax) of the grinding trace is about 0.1 μm. Subsequently, the entire surface of the silicon substrate 100 is etched by about 10 μm with a 32 wt%, 80 ° C. potassium hydroxide aqueous solution, thereby removing the work-affected layer generated by machining (FIG. 4D). As a result, the thickness of the silicon substrate 100 becomes 140 μm. Here, although the surface is roughened by etching, the surface roughness (Rmax) of the silicon substrate is 1 μm or less, and there is no problem in the adhesion of the nozzle substrate 3 in the subsequent process.

Next, an SiO ₂ film 104 serving as an etching mask is formed with a thickness of 1 μm by plasma CVD on the upper surface of the bonded silicon substrate 100 (FIG. 4E). Then, the SiO ₂ film 104 of the portion 11a serving as the discharge chamber, the portion 13a serving as the reservoir, and the portion 26b serving as the electrode extraction portion is patterned by photolithography (FIG. 4F). The SiO ₂ film 104 of the portion 13a serving as a reservoir is half-etched without being completely removed to delay the start of etching of the silicon substrate 100.

Next, the bonded substrate is dipped in a 35 wt% potassium hydroxide aqueous solution at 80 ° C., and the recess 11 b that becomes the discharge chamber 11 and the recess 26 c that becomes the electrode extraction portion 26 are etched halfway. Further, the SiO ₂ film 104 left on the reservoir portion 13a is removed with a hydrofluoric acid aqueous solution, and etching is continued with a 35 wt% potassium hydroxide aqueous solution at 80 ° C. As a result, since the boron diffusion layers 102a and 102b remain without being etched, the bottom of the recess 11b serving as the discharge chamber 11 becomes the vibration plate 12 made of the boron diffusion layer 102b having a thickness of 0.8 μm and becomes the electrode extraction portion 26. A thin film portion 26d made of a boron diffusion layer 102a having a thickness of 3 μm is formed at the bottom of the recess 26c.
On the other hand, the recess 13b that becomes the reservoir 13 that delayed the start of the silicon etching does not proceed to the boron diffusion layer 102b, and the bottom silicon can be left thick (FIG. 5G).

Next, the bonded substrate is immersed in a hydrofluoric acid aqueous solution, and the SiO ₂ film 104 remaining on the surface of the silicon substrate 100 is removed (FIG. 5H). Here, since the thin film portion 26d forming the bottom of the electrode extraction portion 26 is thick and has high strength, the thin film portion 26d is not cracked in the middle of the process. Accordingly, since the space between the silicon substrate 100 and the electrode substrate 2 is completely sealed from the bonding of the substrate to the present step, it is possible to prevent the processing liquid from entering the actuator part in the middle step. Therefore, the manufacturing yield of the inkjet head can be greatly improved.

Next, as a mask member, a silicon mask (which may be a metal mask) having an opening other than at least the electrode extraction portion 26 is used. A SiO ₂ film 105 is formed with a thickness of 2 μm by a pressure CVD apparatus or the like (FIG. 5I).
Next, using a dry etching apparatus, dry etching is performed on the thin film portion 26d formed of the boron diffusion layer 102a and the insulating film 14 remaining at the bottom of the electrode extraction portion 26 in which the SiO ₂ film 105 is not formed and is open. (Fig. 5 (j)).

Here, a schematic configuration of the jig used in the above-described step (FIG. 5I) is shown in comparison with FIG. (A) of the same figure is a structural example of the conventional jig | tool, (b) is a structural example of the jig | tool used by this 1st manufacturing method.
In the conventional case, as shown in FIG. 8A, a bonded substrate is set in a dry etching lower jig 500 through positioning pins 501 and a portion corresponding to the electrode extraction portion 26 is opened on the metal. The mask 502 is set through the positioning pins 501. Further, an outer periphery pressing jig 503 for pressing the outer peripheral portion of the metal mask 502 is placed thereon, and the substrate and the metal mask 502 are brought into close contact with each other.
Next, the substrate was set together with the jig in the etching chamber of the dry etching apparatus, dry etching was performed, and the electrode extraction portion 26 was opened.

However, the conventional manufacturing method has the following problems.
(1) When the substrate and the metal mask are stacked as shown in FIG. 8A, the adhesion between the substrate and the metal mask has a problem that the pressing by the outer periphery pressing jig is not sufficiently effective. For this reason, the etching gas flows into the gap between the substrate and the metal mask during dry etching, and etching of the portion other than the electrode extraction portion proceeds, resulting in a shape defect.
(2) When etching is performed using this jig, the etching rate is uniform across the wafer surface due to the temperature rise of the jig during etching and the change in the flow of the etching gas in the chamber caused by the jig. Sexually deteriorates. In other words, it is necessary to lengthen the etching time in order to secure a desired etching amount and open the electrode extraction portion. When the etching time is lengthened, the processing capability of the apparatus is lowered and the etching of the gap between the substrate and the metal mask is enlarged, so that the shape is further deteriorated.

On the other hand, in the case of the first embodiment, as shown in FIG. 8B, the substrate is set on the lower jig 510 for CVD apparatus through the positioning pins 501 and silicon other than the electrode take-out portion 26 is opened thereon. Mask 512 is placed through positioning pins 511.
Next, the substrate is set together with the jig in the chamber of the CVD apparatus, and a SiO ₂ film is formed with a thickness of 2 μm (see FIG. 5I).

Therefore, the manufacturing method according to the first embodiment has the following effects.
(1) When forming the SiO ₂ film, gas flows from the gap between the silicon mask and the substrate, and a slight amount of SiO ₂ film is formed in the electrode extraction portion. When the electrode extraction portion is opened by dry etching, Since the slightly formed SiO ₂ film can also be removed by etching, a good opening with high processing accuracy without a shape defect is possible.
(2) Since the protective mask for the discharge chamber and reservoir when dry-etching the electrode lead-out portion is a SiO ₂ film, there is no etching gas wraparound, there is no defective shape of the discharge chamber or reservoir, and processing accuracy is very high high. Further, the substrate can be set directly without setting a jig in the etching chamber, the uniformity of the etching rate within the wafer surface can be improved, and the etching time can be shortened. Therefore, when dry etching the electrode lead-out portion, a jig is not required as in the prior art, and therefore there are no restrictions due to the shape, size, etc. of the jig.

With reference to FIG. 5 again, the manufacturing method of the first embodiment will be described.
The SiO ₂ film 105 remaining on the surface of the silicon substrate 100 is removed by dry etching (FIG. 5 (k)). Here, it is desirable to perform dry etching under selective etching conditions such that the borosilicate glass below the opened electrode extraction portion 26 is not etched as much as possible.

  Next, for example, an epoxy adhesive of the sealing material 24 is used to close a gap formed between the silicon substrate 100 and the electrode substrate 2 from the opening of the electrode take-out portion 26 whose bottom is opened as described above. And the actuator part is sealed (FIG. 6L).

  As described above, after the silicon substrate 100 is bonded to the electrode substrate 2 prepared in advance, the thin cavity substrate 1 is manufactured based on the silicon substrate 100.

  Finally, a separately manufactured nozzle substrate 3 is bonded to the cavity substrate 1 (FIG. 6 (m)) and diced to complete a head chip (a main body of the inkjet head 10) (FIG. 6 (n)).

According to the ink jet head manufacturing method of the first embodiment, in addition to the effect that the processing accuracy can be improved without using a jig when the electrode lead-out portion 26 is opened by dry etching as described above. Furthermore, there are the following effects. That is, SiO ₂ films 101a and 101b having a diffusion constant lower than that of silicon are formed on the surface of the silicon substrate 100 that is the base of the cavity substrate 1 before bonding to the electrode substrate 2 that has been prepared in advance, and then bonded. after opening the corresponding portion 26a to the electrode extraction portion 26 of the SiO ₂ film 101a face side, selectively diffusing a high concentration of boron on the bonding surface side of the silicon substrate 100 through the opening and the SiO ₂ film 101a By doing so, the thick boron diffusion layer 102a can be selectively formed in the portion 26a corresponding to the electrode extraction portion 26, and the thin boron diffusion layer 102b can be selectively formed in the other portions.
Accordingly, the bottom portion of the portion where the bottom area of the concave portion is large and easily breaks like the electrode extraction portion 26 can be thickened, so that the strength is increased and it is difficult to break. As a result, it is possible to prevent the processing liquid from entering the gap between the silicon substrate 100 and the electrode substrate 2 during the processing of the cavity substrate 1, and the yield can be significantly improved.

Further, since the thin boron diffusion layer 102b is formed in the portion other than the electrode extraction portion 26, the vibration plate 12 can be formed of an extremely thin thin film, and the thickness accuracy of the vibration plate 12 can be increased by the etching stop action. Can be formed.
Further, since the partially thick boron diffusion layer 102a and the thin boron diffusion layer 102b are simultaneously formed on the bonding surface side of the silicon substrate 100, the diffusion process can be completed once and the process can be simplified.

Further, as described above, using the silicon substrate 100 in which the partially thick boron diffusion layer 102a and the thin boron diffusion layer 102b are simultaneously formed, the surface on the boron diffusion layer side is bonded to the electrode substrate 2 prepared in advance. After that, since the silicon substrate 100 is processed into a thin plate, the concave portion to be the discharge chamber 11 and the concave portion to be the reservoir 13 are formed by anisotropic wet etching, so that the cavity substrate 1 can be formed thin, Even if the actuator part is miniaturized and densified, the rigidity of the partition wall of the discharge chamber 11 can be increased, and crosstalk can be prevented.
Furthermore, even if the cavity substrate 1 is made thin, it is fixedly supported by the electrode substrate 2 that is much thicker than the cavity substrate 1, so that the handling property of the cavity substrate 1 is remarkably improved, and breakage such as cracks and chips is prevented. The yield is significantly improved.
In addition, it is possible to increase the diameter of the substrate, and it is possible to take out a large number of inkjet heads from a single substrate, so that productivity can be improved.

  Next, a second manufacturing method of the inkjet head 10 will be described with reference to FIG. FIG. 7 is a process cross-sectional view of the second manufacturing method showing differences from the first manufacturing method. Accordingly, FIG. 7 (h) is the same as the first manufacturing method after the steps from FIG. 4 (a) to FIG. 5 (h), and FIG. 7 (k) and thereafter are from FIG. 6 (l). The process up to (n) is performed.

In FIG. 7 (i-1), a SiO ₂ film 105 having a thickness of 2 μm is formed on the entire upper surface of the bonded substrate by a plasma CVD apparatus or an atmospheric pressure CVD apparatus.
Next, a photoresist 106 is applied to the entire upper surface of the bonded substrate by a spray resist coating apparatus, and then a portion of the SiO ₂ film 105 to be the electrode extraction portion 26 is patterned by photolithography (FIG. 7 (i)). -2), (j-1)).
Here, since the upper surface of the silicon substrate 100 has large unevenness due to etching, a spray resist coating apparatus is used instead of a photoresist coating by spin coating.

Next, using a dry etching apparatus, the thin film portion 26d formed of the boron diffusion layer 102a and the insulating film 14 remaining at the bottom of the electrode extraction portion 26 in which the SiO ₂ film 105 is opened is removed by dry etching (FIG. 7 ( k)).
After that, the inkjet head 10 is manufactured through the steps after FIG.

The manufacturing method according to the second embodiment has the following effects.
(1) Since the SiO ₂ film 105 of the electrode extraction portion 26 is patterned by photolithography, the processing accuracy of the electrode extraction portion 26 is high.
(2) Since the SiO ₂ film 105 is used as a dry etching mask, the etching gas does not circulate and an opening with high processing accuracy is possible.
(3) Since it is not necessary to set a jig in the etching chamber, the in-plane uniformity of the etching rate is improved, and the etching time can be shortened.

  In the above embodiment, the ink jet head and the manufacturing method thereof have been described. However, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the idea of the present invention. For example, by changing the liquid material ejected from the nozzle holes, in addition to inkjet printers, the production of color filters for liquid crystal displays, the formation of light-emitting portions of organic EL display devices, the microarray of biomolecule solutions used for genetic testing, etc. It can be used as a droplet discharge device for various uses such as manufacture of

1 is a schematic configuration diagram of an inkjet head according to an embodiment of the present invention. Sectional drawing of the manufacturing process of the electrode substrate in the manufacturing method of the inkjet head of this invention. Sectional drawing of the manufacturing process of the silicon substrate before joining in the manufacturing method of the inkjet head of this invention. Sectional drawing of the manufacturing process which shows the 1st manufacturing method of the inkjet head of this invention. Sectional drawing of the manufacturing process following FIG. Sectional drawing of the manufacturing process following FIG. Sectional drawing of the manufacturing process which shows the 2nd manufacturing method of the inkjet head of this invention. The comparison figure of schematic structure of a jig.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cavity substrate, 2 electrode substrate, 3 nozzle substrate, 4 drive means, 10 inkjet head, 11 discharge chamber, 12 diaphragm, 13 reservoir, 14 insulating film, 15 common electrode, 21 recessed part, 22 individual electrode, 23 ink supply hole 24, sealing material, 26 electrode extraction part, 26a part corresponding to electrode extraction part (opening), 31 nozzle hole, 32 orifice, 100 silicon substrate, 101a, 101b SiO ₂ film, 102a, 102b boron diffusion layer, 105 SiO ₂ film, 200 glass substrate, 512 silicon mask.

Claims (5)

A step of bonding a silicon substrate to an electrode substrate on which individual electrodes are formed in advance, a step of processing the silicon substrate into a thin plate, a step of forming a plurality of recesses including discharge chambers in the thinned silicon substrate, A method of manufacturing a droplet discharge head including a step of forming an electrode extraction portion for wiring to each of the individual electrodes.
A step of selectively and thickly forming a boron diffusion layer in a portion corresponding to the electrode extraction portion on the bonding surface side of the silicon substrate before bonding;
After the silicon substrate is bonded to the electrode substrate and thinned, the silicon substrate is wet etched from the surface until the boron diffusion layer is reached, and a recess is formed in the electrode extraction portion;
Forming a SiO ₂ film on the silicon substrate using a mask member having an opening other than the electrode extraction part;
Removing and opening the bottom of the concave portion of the electrode extraction portion where the SiO ₂ film is not formed by dry etching; and
A method of manufacturing a droplet discharge head, comprising: A step of bonding a silicon substrate to an electrode substrate on which individual electrodes are formed in advance, a step of processing the silicon substrate into a thin plate, a step of forming a plurality of recesses including discharge chambers in the thinned silicon substrate, A method of manufacturing a droplet discharge head including a step of forming an electrode extraction portion for wiring to each of the individual electrodes.
A step of selectively and thickly forming a boron diffusion layer in a portion corresponding to the electrode extraction portion on the bonding surface side of the silicon substrate before bonding;
After the silicon substrate is bonded to the electrode substrate and thinned, the silicon substrate is wet etched from the surface until the boron diffusion layer is reached, and a recess is formed in the electrode extraction portion;
Forming a SiO ₂ film over the entire surface of the silicon substrate;
Patterning the SiO ₂ film on the bottom surface of the recess of the electrode lead-out portion by photolithography;
Removing and opening the bottom of the recess of the electrode lead-out portion where the SiO ₂ film is opened by dry etching; and
A method of manufacturing a droplet discharge head, comprising:   The step of forming the boron diffusion layer includes forming a thermal oxide film or TEOS film on the bonding surface side of the silicon substrate, opening the thermal oxide film or TEOS film corresponding to the electrode extraction portion, and 3. The method of manufacturing a droplet discharge head according to claim 1, wherein boron is diffused through the opening and the thermal oxide film or TEOS film.   4. The method of manufacturing a droplet discharge head according to claim 1, wherein the bottom of the discharge chamber is formed by a thin boron diffusion layer. 5. The method of manufacturing a droplet discharge head according to claim 1, wherein the silicon substrate is a silicon substrate having a plane orientation of (110).

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