Patent Application
20080057732
1. Technical Field
The present invention relates to a method for manufacturing a silicon substrate, a method for manufacturing a droplet discharging head, and a method for manufacturing a droplet discharging apparatus.
2. Related Art
A droplet discharging head driven by electrostatic force is required to be compact, low cost, densely fabricated, and have stable discharging characteristics. In order to satisfy these requirements, some droplet discharging heads have a four-layer structure composed of an electrode substrate, a cavity substrate, a reservoir substrate, and a nozzle substrate. Among these heads, there are a few cases in which a silicon base material is used as a reservoir substrate. Hence, process stability and yield improvement are required in manufacturing such a few droplet discharging heads in which the above reservoir substrate is used.
Some documents disclosed a droplet discharging head having a four-layer structure, provided with an electrode substrate, a cavity substrate, a reservoir substrate, and a nozzle substrate, and a method for manufacturing the head. For example, JP-A-2006-103167 (in pages 9 and 10, in FIGS. 8 and 9) indicated a method for manufacturing a reservoir substrate in which the reservoir substrate made of a silicon base material is manufactured by etching the silicon base material from the both sides.
The method for manufacturing a droplet discharging head disclosed in the above document, however, in which a reservoir (common droplet chamber) and a nozzle communicating hole are dry etched, has a problem in that a large etching area yields a wide variation in an etched depth and it's shape collapses easily. In addition, a nozzle communicating hole is formed through a silicon base material by etching the both sides of the material. This process easily forms a step inside the nozzle communicating hole due to misalignment. Further, the step sometimes yields a flight curve during a droplet discharging.
There are other examples of methods for manufacturing a droplet discharging head including a reservoir substrate made of a silicon base material. Among them, in a method in which a laser is not used for forming a nozzle communicating hole, a reservoir and the like is patterned after forming the nozzle communicating hole.
The above method needs to protect the nozzle communicating hole with resist to prevent a silicon oxide film formed inside the nozzle communicating hole from being etched. The process of covering the nozzle communicating hole with resist is, however, cumbersome and sometimes lowers a yield. Further, in a method in which a nozzle communicating hole is formed by using a laser, it takes a long time in processing.
An advantage of the invention is to provide a method for manufacturing a silicon substrate that can pattern a silicon base material without using resist, a method for manufacturing a droplet discharging head, and a method for manufacturing a droplet discharging apparatus, and especially, to provide a method for manufacturing a silicon substrate that can pattern a reservoir and an individual electrode terminal part without using resist after forming a nozzle communicating hole and prevent incomplete resist coverage of the nozzle communicating hole, a method for manufacturing a droplet discharging head having the substrate, and a method for manufacturing a droplet discharging apparatus having the head.
A method for manufacturing a silicon substrate according to a first aspect of the invention includes forming a silicon nitride (SiN) film on a patterning area on a surface of a silicon base material, forming a silicon oxide (SiO2) film on an area excluding the patterning area on the surface of the silicon base material after forming the silicon nitride film, removing the silicon nitride film to expose the silicon base material of the patterning area, and etching the silicon base material of the patterning area.
The method enables the patterning area, on which the silicon nitride film is formed, to be patterned without using resist.
A method for manufacturing a silicon substrate according to a second aspect of the invention includes forming a first silicon oxide film on a surface of a silicon base material, forming a silicon nitride film on the first silicon oxide film corresponding to a patterning area on the surface of the silicon base material, forming a second silicon oxide film on the first silicon oxide film excluding the silicon nitride film after forming the silicon nitride film, removing the silicon nitride film, exposing the silicon base material of the patterning area, and etching the silicon base material of the patterning area.
The method enables the patterning area, on which the silicon nitride film is formed, to be patterned without using resist. In addition, the method can prevent the silicon base material from being roughed during a patterning when resist patterning is carried out on the silicon nitride film since the first silicon oxide film is formed under the silicon nitride film.
In this case, the silicon nitride film may be subjected to a resist patterning and etched so as to be formed in a shape of the patterning area.
The method can prevent the silicon base material from being roughed during the patterning since the resist patterning is carried out on the silicon nitride film with the first silicon oxide film formed under the silicon nitride film.
A method for manufacturing a droplet discharging head according to a third aspect of the invention includes a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes forming a silicon nitride film on a patterning area on a surface of a silicon base material, forming a silicon oxide film on an area excluding the patterning area on the surface of the silicon base material after forming the silicon nitride film, removing the silicon nitride film to expose the silicon base material of the patterning area, and etching the silicon base material of the patterning area.
The method can provide the droplet discharging head including the silicon substrate manufactured by the method in which the patterning area, on which the silicon nitride film is formed, is patterned without using resist.
A method for manufacturing a droplet discharging head according to a fourth aspect of the invention includes a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes forming a first silicon oxide film on a surface of a silicon base material, forming a silicon nitride film on the first silicon oxide film corresponding to a patterning area on the surface of the silicon base material, forming a second silicon oxide film on the first silicon oxide film excluding the silicon nitride film after forming the silicon nitride film, removing the silicon nitride film, exposing the silicon base material of the patterning area, and etching the silicon base material of the patterning area.
The method can provide the droplet discharging head including the silicon substrate manufactured by the method in which the patterning area, above which the silicon nitride film is formed, is patterned without using resist, and the surface of which can be prevented from being roughed during the patterning.
According to a fifth aspect of the invention, a method for manufacturing a droplet discharging head that is provided with a nozzle substrate having a nozzle hole, a cavity substrate having a nozzle communicating hole communicating with the nozzle hole and a discharge chamber discharging a droplet from the nozzle hole by pressure produced inside the discharge chamber, and a reservoir communicating with the discharge chamber includes a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes forming a silicon nitride film on a patterning area on a surface of a silicon base material, forming a silicon oxide film on an area excluding the patterning area on the surface of the silicon base material after forming the silicon nitride film, removing the silicon nitride film to expose the silicon base material of the patterning area, and etching the silicon base material of the patterning area. The reservoir substrate is made of the silicon base material.
The method can provide the droplet discharging head including the reservoir substrate that is made of the silicon base material and manufactured by the method in which the patterning area, on which the silicon nitride film is formed, is patterned without using resist.
According to a sixth aspect of the invention, a method for manufacturing a droplet discharging head that is provided with a nozzle substrate having a nozzle hole, a cavity substrate having a nozzle communicating hole communicating with the nozzle hole and a discharge chamber discharging a droplet from the nozzle hole by pressure produced inside the discharge chamber, and a reservoir communicating with the discharge chamber includes a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes forming a first silicon oxide film on a surface of a silicon base material, forming a silicon nitride film on the first silicon oxide film corresponding to a patterning area on the surface of the silicon base material, forming a second silicon oxide film on the first silicon oxide film excluding the silicon nitride film after forming the silicon nitride film, removing the silicon nitride film, exposing the silicon base material of the patterning area, and etching the silicon base material of the patterning area. The reservoir substrate is made of the silicon base material.
The method can provide the droplet discharging head including the reservoir substrate that is made of the silicon base material and is manufactured by the method in which the patterning area, on which the silicon nitride film is formed, is patterned without using resist and roughing the surface of the silicon base material.
In the fifth aspect of the invention, the patterning area may serve to form the reservoir and an individual electrode terminal part, and in the etching step, the silicon base material of the patterning area may be etched to form the reservoir and individual electrode terminal part.
The method can provide the droplet discharging head including the silicon substrate manufactured by the method in which the patterning area, on which the silicon nitride film is formed, is patterned without using resist and etched to form the reservoir and the individual electrode terminal part.
According to a seventh aspect of the invention, a method for manufacturing a droplet discharging head that is provided with a nozzle substrate having a nozzle hole, a cavity substrate having a nozzle communicating hole communicating with the nozzle hole and a discharge chamber discharging a droplet from the nozzle hole by pressure produced inside the discharge chamber, and a reservoir communicating with the discharge chamber includes a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes: forming a silicon nitride film on a patterning area on a first surface of the silicon base material, the patterning area serving to form the reservoir and an individual electrode terminal part; forming a silicon oxide film on an area excluding the patterning area on the first surface of the silicon base material after forming the silicon nitride film; etching the silicon base material from a second surface opposite to the first surface to form the nozzle communicating hole; removing the silicon nitride film to expose the silicon base material of the patterning area after forming the nozzle communicating hole; and etching the silicon base material of the patterning area to form the reservoir and individual electrode terminal part. The reservoir substrate is made of the silicon base material.
This method allows the patterning area serving to form the reservoir and the individual electrode terminal part on the reservoir base material to be patterned without using resist, and also the nozzle communicating hole to be prevented from incomplete resist coverage.
According to an eighth aspect of the invention, a method for manufacturing a droplet discharging head that is provided with a nozzle substrate having a nozzle hole, a cavity substrate having a nozzle communicating hole communicating with the nozzle hole and a discharge chamber discharging a droplet from the nozzle hole by pressure produced inside the discharge chamber, and a reservoir communicating with the discharge chamber includes a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes: forming a first silicon oxide film on a first surface of a silicon base material, forming a silicon nitride film on the first silicon oxide film corresponding to a patterning area on the first surface of the silicon base material, the patterning area serving to form the reservoir and an individual electrode terminal part; forming a second silicon oxide film on the first silicon oxide film excluding the silicon nitride film after forming the silicon nitride film; etching the silicon base material from a second surface opposite to the first surface to form the nozzle communicating hole; removing the silicon nitride film to expose the silicon base material of the patterning area after forming the nozzle communicating hole; and etching the silicon base material of the patterning area to form the reservoir and individual electrode terminal part. The reservoir substrate is made of the silicon base material.
This method allows the patterning area serving to form the reservoir and the individual electrode terminal part on the reservoir base material to be patterned without using resist, and also the nozzle communicating hole to be prevented from incomplete resist coverage. In addition, the first silicon oxide film formed under the silicon nitride film can prevent the surface of the reservoir base material from being roughed when the silicon nitride film is patterned. The first silicon oxide film also can prevent cooling gas from being leaked when the nozzle communicating hole is formed by dry etching.
A method for manufacturing a ninth aspect of the invention includes a method for manufacturing a droplet discharging apparatus including a method for manufacturing a droplet discharging head including a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes forming a silicon nitride film on a patterning area on a surface of a silicon base material, forming a silicon oxide film on an area excluding the patterning area on the surface of the silicon base material after forming the silicon nitride film, removing the silicon nitride film to expose the silicon base material of the patterning area, and etching the silicon base material of the patterning area.
The method can provide the droplet discharging apparatus including the droplet discharging head having the silicon substrate manufactured by the method in which the patterning area, on which the silicon nitride film is formed, is patterned without using resist.
A method for manufacturing a tenth aspect of the invention includes a method for manufacturing a droplet discharging apparatus including a method for manufacturing a droplet discharging head including a method for manufacturing a silicon substrate. The method for manufacturing a silicon substrate includes forming a first silicon oxide film on a surface of a silicon base material, forming a silicon nitride film on the first silicon oxide film corresponding to a patterning area on the surface of the silicon base material, forming a second silicon oxide film on the first silicon oxide film excluding the silicon nitride film after forming the silicon nitride film, removing the silicon nitride film, exposing the silicon base material of the patterning area, and etching the silicon base material of the patterning area.
The method can provide the droplet discharging apparatus including the droplet discharging head having the silicon substrate manufactured by the method in which the patterning area, on which the silicon nitride film is formed, is patterned and etched without using resist and roughing the surface of the silicon base material.
The invention will be described with reference to the accompanying drawings, wherein like number reference like elements.
Although it will be described that the nozzle substrate having the nozzle hole is located on an electrode substrate, the nozzle substrate is mostly located under the electrode substrate in actual use.
As shown in
The electrode substrate 2 has a thickness of about 1 mm and is made of heat resistance hard glass such as borosilicate glass having an approximate linear expansion coefficient to that of silicon, for example. In addition, a plurality of concave parts (electrode groove) 20, serving as an electrode chamber and having a depth of about 0.2 μm, for example, is formed by etching corresponding to respective discharge chambers (described later) formed in the cavity substrate 3. The concave parts 20 are formed in facing two lines, in each of which they are arranged with a constant interval. Inside each concave part 20, an individual electrode 22 and a terminal part 23 continuously formed from the individual electrode 22 are formed by sputtering indium tin oxide (ITO), for example. The individual electrodes 22 and the terminal parts 23 form electrode lines E1 and E2, in each of which, each long side of the individual electrodes 22 and the terminal parts 23 is in parallel each other. Each individual electrode 22 also arranged so as to face respective vibration plates (described later) prepared in the cavity substrate 3. Here, the pattern shape of the concave part 20 disposed in the electrode substrate 2 is made slightly larger than the shape of an electrode (the individual electrode 22 and the terminal part 23) since the electrode is prepared inside the concave part 20.
In the first embodiment, ITO, which is transparent and includes tin oxides doped as an impurity, is used for the material of the electrode prepared inside the concave part 20. ITO is deposited inside the concave part 20 as a film with a thickness of 0.1 μm by sputtering, for example. Therefore, a gap G formed between a vibration plate (described later) and the electrode depends on the depth of the concave part 20, the thickness of the electrode, and the vibration plate (TEOS film). The gap G greatly influences on discharge characteristics. The material for the electrode is not limited to ITO, but metal such as chromium may be used. The reason why ITO is used in the first embodiment is that the inside of the gap G is easily observed, discharge is easily checked due to its transparency and the like. The electrode substrate 2 also has a liquid supply hole 70a communicating with a reservoir (described later).
Between the electrode lines E1 and E2, an IC mount concave part (mount groove) 21 is formed orthogonally with respect to the long side direction of the individual electrode 22 so as to have a depth similar to that of the concave part 20 serving as the electrode chamber. In the IC mount concave part 21, three mount lead wires 26 are formed parallel reach other in the groove direction of the IC mount concave part 21 by sputtering ITO.
The driver IC 60 is mounted to the IC mount concave part 21 and connected to the terminal part 23 of the individual electrode 22 included in the electrode lines E1 and E2, allowing a driving signal to be supplied to the electrode lines E1 and E2 to control an actuator. While the droplet discharging head 1 has two driver ICs 60, the number of driver ICs 60 may be one or more than two.
The cavity substrate 3 is made of monocrystalline silicon having a (110) plane direction with a thickness of about 50 μm. In the cavity substrate 3, a concave part 32a is formed that serves as a discharge chamber 32 having a vibration plate 30 as the bottom wall thereof. The concave parts 32a are formed in two lines corresponding to individual electrodes 22 (in the electrode lines E1 and E2) of the electrode substrate 2. The cavity substrate 3 also has a first hole 33 passing through the cavity substrate 3 between two lines composed of the concave part 32a, and a common electrode 34 for applying voltage to the vibration plate 30. The common electrode 34 connects to an FPC 35a.
The vibration plate 30, prepared as the bottom wall of the concave part 32a serving as the discharge chamber, is a highly boron-doped layer. In order to form the vibration plate 30 having a desired thickness, boron-doped layer having the same thickness is formed. The thickness of the vibration plate 30 and the volume of the concave part 32a serving as the discharge chamber 32 are formed with high accuracy by using a called etching stop technique. The etching stop technique utilizes that an etching rate is enormously decreased in a highly doped region (about 5×1019 atoms·cm−3 or more) of boron serving as a dopant when silicon is subjected to an anisotropic wet etching with an alkaline aqueous solution.
The cavity substrate 3 has an insulation film 31 made of tetra-ethyl-ortho-silicate or tetra-ethoxy-silane (TEOS) with a thickness of 0.1 μm on the lower surface (the surface facing the electrode substrate 2). The insulation film 31 is formed by plasma chemical vapor deposition (CVD). The insulation film 31 prevents insulation breakdown and short circuits when the vibration plate 30 is driven. The cavity substrate 3 also has a liquid supply hole 70b, corresponding to the liquid supply hole 70a of the electrode substrate 2, passing through the cavity substrate 3. In addition, between the first hole 33 of the cavity substrate 3 and the concave parts 20 of the electrode substrate 2, a sealing member 71 is disposed to prevent the gap G from penetration of moisture or the like. The sealing member 71 can prevent the vibration plate 30 from adhering to the individual electrode 22.
The reservoir substrate 4 is made of monocrystalline silicon having a thickness of 180 μm, for example. The reservoir substrate 4 has two concave parts 40a, located at both sides thereof in the width direction so as to face each other. Each of the concave parts 40a serves as a reservoir 40 that supplies, for example, liquid like ink (hereinafter, referred to as ink) to the discharge chamber 32 of the cavity substrate 3. The concave part 40a has a supply inlet 41 on the bottom surface thereof to transfer ink from the reservoir 40 to each discharge chamber 32. The concave part 40a has a liquid supply hole 70c on the bottom surface thereof. The liquid supply hole 70c passes through the bottom surface of the concave part 40a. The liquid supply hole 70c formed in the reservoir substrate 4, the liquid supply hole 70b formed in the cavity substrate 3, and the liquid supply hole 70a formed in the electrode substrate 2 communicate each other to form a liquid supply hole 70 that supplies ink from an external source to the reservoir 40 when the reservoir substrate 4, the cavity substrate 3, and the electrode substrate 2 are bonded. In addition, between the reservoirs 40 facing each other in the reservoir substrate 4, a second hole 42 passing through the reservoir substrate 4 is formed.
The first hole 33 prepared in the cavity substrate 3 communicates with the second hole 42 prepared in the reservoir substrate 4 and further the resulting holes connect the IC mount concave part 21 prepared on the electrode substrate 2 to form an individual electrode terminal part 72. Inside the individual electrode terminal part 72, the driver IC 60 is housed while it is fixed to the IC mount concave part 21.
In addition, between the concave part 40a and the second hole 42 of the reservoir substrate 4, a nozzle communicating hole 35 communicating with the discharge chamber 32 is disposed to transfer ink from the discharge chamber 32 to a nozzle hole (described later) of the nozzle substrate 5.
The reservoir substrate 4 has a second concave part 39b on the surface thereof facing the concave part 32a of the cavity substrate 3 (on the bottom surface of the reservoir substrate 4). The second concave part 39b serves as a second discharge chamber 39 and form the discharge chamber 32 together with the concave part 32a of the cavity substrate 3 when the reservoir substrate 4 and the cavity substrate 3 are bonded.
The nozzle substrate 5 is made of a silicon base material having a thickness of about 50 μm, for example. The nozzle substrate 5 has a plurality of nozzle holes 43, each communicating with the respective nozzle communicating holes 35 of the reservoir substrate 4. Each of the nozzle holes 43 has a large-diameter part and a small-diameter part as two steps to improve straight flying property when a droplet is discharged.
In the droplet discharging head 1 structured as described above, the driver IC 60 fixed to the IC mount concave part 21 prepared in the electrode substrate 2 is housed in the individual electrode terminal part 72, which is closed by the nozzle substrate 5, the cavity substrate 3, the reservoir substrate 4 and the electrode substrate 2. That is, the individual electrode terminal part 72 is closed by the nozzle substrate 5 covering the upper surface of the individual electrode terminal part 72, the electrode substrate 2 covering the lower surface of the individual electrode terminal part 72, and the cavity substrate 3 and the reservoir substrate 4 both of which cover respective side surfaces of the individual electrode terminal part 72.
Next, the operation of the droplet discharging head 1 will be described with reference to
For example, the driver IC 60 oscillates at 24 kHz and applies a pulse voltage of 30V between the electrodes to supply electric charges. When the individual electrode 22 is charged positive by supplying electric charges, the vibration plate 30 is charged negative and thereby is attracted to the individual electrode 22 to bend. This bending increases the volume of the discharge chamber 32. When electric charge supply to the individual electrode is stopped, the vibration plate 30 returns to the original shape. At the same time, the volume of the discharge chamber 32 also returns to the original one, resulting pressure discharging a droplet equivalent to the difference in the volume of the discharge chamber 32. The discharged droplet is landed on, for example, a recording paper as a recoding object to perform a recoding. Here, such method is a called drawing shot. There is also a called pushing shot discharging a droplet by using a spring or the like. Again, electric charges are supplied to the individual electrode 22 by applying a pulse voltage, so that the vibration plate 30 bends toward the individual electrode 22. As a result, ink is resupplied from the reservoir 40 into the discharge chamber 32 through the supply inlet 41.
In the droplet discharging head 1, ink is supplied to the reservoir 40 through a droplet supply tube (not shown) connected to the liquid supply hole 70, for example.
Also, in the first embodiment, the FPC 35a is connected to the driver IC 60 so that the longitudinal direction of the FPC 35a is in parallel with the short side direction of the individual electrode 22 included in the electrode lines. This structure allows the droplet discharging head 1 including the electrode lines E1 and E2, and the FPC 35a to be compactly connected.
Next, manufacturing steps of the droplet discharging head 1 will be described with reference to
First, the manufacturing steps of a reservoir base plate 4 made of a silicon base material will be described with reference to
(b) As shown in
In the above steps, the silicon nitride film 402 is formed in step (b) after step (a). Here, in step (a), the silicon oxide films 401a and 401b are formed on the surfaces A and B of the silicon base material 400, respectively, while in step (b), the silicon nitride film 402 is formed on the surface A of the silicon base material 400 by plasma CVD. However, the silicon nitride film 402 can be formed on the surface A of the silicon base material 400 by plasma CVD after mirror polishing the surfaces A and B of the silicon base material 400 without forming the silicon oxide films 401a and 401b on the surfaces A and B, respectively.
(c) A resist is coated on the silicon nitride film formed on the surface A. Then, as shown in
In the process, in which the silicon nitride film 402 is formed after forming the silicon oxide films 401a and 401b on the silicon base material 400 and then resist patterning is carried out on the silicon nitride film 402, the surface of the silicon base material 400 is prevented from being etched by etching gas since the silicon oxide film 401a, the layer under the silicon nitride film 402, functions as a mask.
(d) Then, as shown in
(e) A resist is coated above the surfaces A and B of the silicon base material 400. Then, resist patterning is carried out for a part 350, in which the nozzle communicating hole 35 will be formed, on the surface B. Next, the silicon oxide film 401b is patterned by etching with a fluoric acid aqueous solution as shown in
(f) A resist is coated above the surfaces A and B of the silicon base material 400. Then, resist patterning is carried out for a part 410 in which the supply outlet 41 through which the reservoir 40 communicates with the discharge chamber 32 will be formed, a part 700c in which the liquid supply hole 70c to supply ink from the cavity substrate 3 will be formed, and a part (not shown) in which the hole 42 included in the individual electrode terminal part 72 will be formed, above the surface B in which the part 350 serving to form the nozzle communicating hole 35 is formed. Next, the silicon oxide film 401b is patterned by etching with a fluoric acid aqueous solution by about 0.8 μm deep so as to leave the silicon oxide film having a thickness of about 0.4 μm, as shown in
(g) A resist is coated above the surfaces A and B of the silicon base material 400. Then, resist patterning is carried out for a part 391b, in which a second concave part 390b will be formed, above the surface B in which the part 350 serving to form the nozzle communicating hole 35 is formed. Next, the silicon oxide film 401b is patterned by etching with a fluoric acid aqueous solution by about 0.5 μm deep so as to leave the silicon oxide film 401b having a thickness of about 0.7 μm, as shown in
(h) The part 350 serving to form the nozzle communicating hole 35 is etched by about 150 μm deep as shown in
(i) A resist is coated above the surface A. The silicon oxide film 401b that remains at the part 410, in which the supply inlet 41 will be formed, and the like is etched as shown in
(j) The part 410 serving to form the supply inlet 41 is etched by about 20 μm deep (the part 350 serving to form the nozzle communicating hole 35 is etched by about 170 μm deep) as shown in
(k) A resist is coated above the surface A. The silicon oxide film 401b that remains at the part 391b, in which the second concave part 390b will be formed, and the like is etched as shown in
(l) The part 391b, in which the second concave part 390b will be formed, is etched by about 10 μm deep (the part 350 corresponding to the nozzle communicating hole 35 is etched by about 180 μm deep and the part 410 serving to form the supply inlet 41 and the like are etched by about 30 μm deep) as shown in
(m) The silicon oxide films 401a and 401b are etched as shown in
(n) As shown in
(o) Silicon oxide film slightly formed on the surface of the silicon nitride film 402 is removed by soaking the silicon base material 400 in a fluoric acid aqueous solution (not shown). Then, the silicon base material 400 is soaked in a heated phosphoric acid aqueous solution (180° C.) to remove the silicon nitride film 402 that remains on the part 400a in which the reservoir 40 will be formed and a part (not shown) in which the second hole 42 included in the individual electrode terminal part 72 will be formed, as shown in
(p) The silicon base material 400 is soaked in a fluoric acid aqueous solution to etch the silicon oxide film 401a that covers the part 400a in which the concave part 40a of the reservoir 40 will be formed and a part (not shown) in which the second hole 42 included in the individual electrode terminal part 72 will be formed so that the surface of the silicon base material 400 is exposed as shown in
(q) The silicon base material 400 is soaked in a potassium hydrate aqueous solution of a concentration of 25 wt % to etch the part 440a in which the concave part 40a of the reservoir 40 will be formed and the part (not shown) in which the second hole 42 included in the individual electrode terminal part 72 as shown in
(r) The silicon oxide films 401a and 401b are removed as shown in
Through the above manufacturing steps from (a) to (r), the reservoir substrate 4 is achieved as shown in
In the manufacturing steps, the concave part 40a of the reservoir 40 is formed by etching the part 440a serving to form the concave part 40a of the reservoir 40 while the second hole 42 included in the individual electrode terminal part 72 is formed by etching the part serving to form the second hole 42 included in the individual electrode terminal part 72. The etching process is carried out after the nozzle communicating hole 35 is passed through (
The cathode 52 has a concave part 56, which is filled with base material cooling gas such as helium to prevent the silicon base material 400 from being over heated. Overheating the silicon base material 400 may affect an etching speed and the oxidization process of the silicon base material 400. If a resist is used as a mask, the resist may get burned. Thus, the temperature of the silicon base material 400 is maintained with base material cooling gas. In this regard, the silicon base material 400 functions as a called lid to prevent base material cooling gas from leaking in the inside of the chamber 51.
For dry etching the silicon base material 400, the silicon base material 400 is placed inside the chamber 51 of the dry etching apparatus 50 as shown in
Next, steps to manufacture the droplet discharging head 1 by using the reservoir substrate 4 manufactured as described above will be described.
While the component of droplet discharging head 1 is simultaneously formed in a plurality of numbers from a silicon wafer in practice, only a part of them is shown in
(a) As shown in
(b) A cavity base material 300 is prepared. The cavity base material 300 is formed to have a thickness of 220 μm by mirror polishing one surface of a silicon base material having a (110) plane direction and low oxygen concentration. To the mirror polished surface of the cavity base material 300, a highly boron doped layer (not shown) is formed with a thickness equal to that of the vibration plate. In addition, on the surface of the boron doped layer, a TEOS insulation film (not shown) is formed with a thickness of 0.1 μm.
Next, the cavity base material 300 and the electrode substrate 2 on which a pattern has been formed are heated at 360° C. Then, the cavity base material 300 and the electrode substrate 2 are anodic bonded by applying a voltage of 800 V after the electrode substrate 2 is connected to a negative pole while the cavity base material 300 is connected to a positive pole, as shown in
(c) After the anodic bonding, the surface of the cavity base material 300 is grinded to a thickness of about 60 μm. Then, the cavity base material 300 is etched by about 10 μm with a potassium hydrate aqueous solution of a concentration of 32 wt % to remove a work-affected layer. As a result, the cavity base material having a thickness of about 50 μm is achieved as shown in
(d) The cavity base material 300, which has been subjected to the anodic bonding, is etched by using a potassium hydrate aqueous solution to form the concave part 32a serving to form the discharge chamber 32. In this silicon etching process, etching is stopped at the boron doped layer due to decreasing of the etching rate. This process suppresses the surface of the vibration plate 30 from being roughed to increase the thickness accuracy, allowing the discharge performance of the droplet head 1 to be stabilized. In this regard, silicon thin film remains in the through holes such as the first hole 33 included in the individual electrode terminal part 72. In order to remove the film, plasma is applied only to the through hole for RIE dry etching after fixing a silicon mask on the surface of the cavity base material 300. As a result, the film is removed to form an opening whereby the cavity substrate 3 is achieved as shown in
(e) The bonded base materials shown in
(f) The reservoir substrate 4, which has been manufactured in steps shown in
(g) As shown in
(h) As shown in
The droplet discharging head 1 according to the invention can be easily handled since parts such as the concave part 32a serving to form the discharge chamber 32 are formed in the cavity base material 300 after the cavity base material 300 and the electrode substrate 2 are bonded. The easy handling can reduce the breakage of the base material and achieve a larger size base material. The larger size base material allows the larger number of droplet discharging heads 1 to be manufactured from a single base material, enabling the productivity to be increased. In addition, stacking the reservoir substrate 4 thicker than the cavity substrate 3 on the cavity substrate 3 reduces the flow path resistance of the reservoir 40, allowing discharge capacity to be improved and a head to be downsized.
The reservoir substrate 4 of the droplet discharging head 1 is processed as follows: the silicon nitride film 402 is formed on the patterning areas for the concave part 40a of the reservoir 40 and the second hole 42 of the individual electrode terminal part 72; the silicon oxide film 401a is formed as a mask in silicon etching; the silicon nitride film 402 is removed; and the concave part 40a of the reservoir 40 and the second hole 42 of the individual electrode terminal part 72 are patterned. Using such manufacturing method allows the concave part 40a of the reservoir 40 and the second hole 42 of the individual electrode terminal part 72 to be patterned without resist after forming the nozzle communicating hole 35. As a result, incomplete resist coverage of the nozzle communicating hole 35 can be prevented.
Also, in manufacturing the reservoir substrate 4 of the droplet discharging head 1, the silicon oxide film 401a can be formed thin as an underlayer prior to forming the silicon nitride film 402. The underlayer can prevent the surface of the reservoir base material 400 from being roughed in patterning the silicon nitride film 402, and also prevent cooling gas from being leaked when the nozzle communicating hole 35 is passed through during the dry etching.
As shown in
On the other hand, the drum 601 is rotary driven by a motor 606 with a belt 605 and the like. In addition, printing control means 607 drives the lead screw 604 and the motor 606 based on printing image data and a control signal, and an oscillation circuit (not shown) to vibrate the vibration plate 30. As a result, a printing is carried out on the printing paper 610 under the control of the printing control means 607.
While liquid is discharged to the printing paper 610 as ink in this case, liquid discharged from the droplet discharging head 1 is not limited to ink. A variety of liquid may be discharged from a droplet discharging head provided in respective apparatuses used in the following exemplary cases. In an application where liquid is discharged to a substrate serving as a color filter, liquid containing a pigment may be used. In another application where liquid is discharged to a substrate serving as a display panel (such as OLED) using an electroluminescent element such as an organic compound, liquid containing a compound serving as an light-emitting element may be used. In another application where liquid is discharged on a substrate for forming electrical wire lines, liquid containing conductive metal may be used. When liquid is discharged to a substrate serving as a biomolecule micro array by using the droplet discharging head as a dispenser, liquid may be discharged that contains a probe such as deoxyribo nucleic acids (DNA), other nucleic acids such as ribo nucleic acids and peptide nucleic acids, and other proteins. The apparatus also can be used to discharge a dye for clothes or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-232596 | Aug 2006 | JP | national |
