JP3942810B2 - Electrostatic ink jet head and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording head for an ink jet printer (electrostatic ink jet head) having an electrostatic actuator utilizing electrostatic force, and more specifically, an electrostatic ink jet head applied to a printer, a copying machine, a facsimile machine and the like. And a manufacturing method thereof.
[0002]
[Prior art]
Conventionally, an electrostatic inkjet head that discharges ink droplets by using electrostatic force is opposed to the vibration plate and a substrate that forms a vibration plate that is part of a liquid chamber communicating with the ink discharge nozzle. And an electrode substrate having individual electrodes disposed opposite to each other with a gap on the opposite side of the liquid chamber, and applying a voltage between the diaphragm and the individual electrodes Then, by deforming the diaphragm and generating pressure in the liquid chamber, the ink operates to be ejected from the nozzles.
[0003]
In an electrostatic inkjet head, in order to improve ink ejection performance, suppress variation in print quality, and reduce the driving voltage, the pressure applied to the diaphragm is applied between the diaphragm and the individual electrodes. Since it is inversely proportional to the square of the gap distance, the structure of the gap is becoming more and more important, such as improving the gap gap dimensional accuracy, narrowing the gap gap, and devising the shape of the gap gap. . Various measures have conventionally been taken with respect to the means for forming such a gap structure.
[0004]
For example, in Japanese Patent Laid-Open No. 6-071882 “Inkjet Head and Manufacturing Method Thereof”, as shown in FIG. 7, any one of bonding surfaces of a substrate 301 forming a diaphragm 305 and an electrode substrate 302 having an individual electrode 321. One or both surfaces are surrounded by SiO 2 so as to surround the vibration chamber 305 and the individual electrode 321 respectively. ₂ Films 341 and 342 are formed, and the SiO 2 ₂ An example is disclosed in which the gap dimension is set to 0.05 to 2.0 μm by maintaining the film thicknesses of the films 341 and 342 with constant accuracy. That is, SiO ₂ Films 341 and 342 are formed as gap spacers, and the SiO 2 ₂ The film is formed with high accuracy using various methods such as a thermal oxidation method, a vapor deposition method, a sputtering method, and a CVD method.
[0005]
In Japanese Patent Laid-Open No. 9-039235, “Inkjet Head and Driving Method Therefor”, as shown in FIG. 8, the gap G between the diaphragm 451 and the individual electrode 410 has a small gap G1, an intermediate gap G2, and a large gap G2. A stepped step is provided on the electrode substrate 404 so as to form a step with the gap G3, and an individual electrode 410 is formed on the step.
Even when the same drive voltage is applied, the portion of the diaphragm 451 corresponding to the gap G1 smaller than the portion of the diaphragm 451 corresponding to the larger gaps G2 and G3 is first attracted to the individual electrode 410 side. Starting from the site, elastic displacement is gradually induced over the entire diaphragm 451. Further, the amount of contact of the vibration plate 451 with the insulating film 415 formed on the individual electrode 410 can be changed stepwise according to the amount of deflection of the vibration plate 451, so that the compliance of the ink vibration system is stepped. By changing the shape, the ejection characteristics such as the ejection amount and size of the ink droplets can be controlled.
The electrode substrate for forming such a stepped step is made of borosilicate glass, and if the step is formed with high dimensional accuracy, excellent ink discharge performance can be achieved.
[0006]
In Japanese Patent Laid-Open No. 9-193375 “Recording Head”, a non-parallel gap is formed between a substrate on which a vibration plate and an electrode substrate having individual electrodes are arranged in non-parallel. Cases have been disclosed. By adopting such a non-parallel arrangement, a large electrostatic force acts on the part with the smallest gap width, so when the position of the diaphragm in the part begins to bend and the gap interval begins to narrow, the part becomes the starting point. As a result, the distance between the peripheral diaphragm and the individual electrodes is gradually reduced. Accordingly, a large displacement can be obtained with a low driving voltage, and variations in the ink ejection amount and ejection speed can be suppressed.
The formation of such a non-parallel gap is realized by forming the electrode substrate in a non-parallel shape and attaching individual electrodes on the non-parallel electrode substrate.
[0007]
Alternatively, a method for realizing low voltage driving by gradually decreasing the gap between the substrate forming the diaphragm and the electrode substrate having the individual electrodes from the central portion toward the peripheral portion of the individual electrodes has already been presented. (Japanese Patent Application No. 11-349783). By optimizing the shape of the non-parallel gap that gradually decreases the gap interval toward the periphery, the driving voltage at which the diaphragm is displaced can be lowered or the amount of displacement can be increased. It is also possible. The non-parallel gap is formed by first forming a photoresist layer formed on the electrode substrate into the gap shape by photolithography, and then using the photoresist layer as a mask to the electrode substrate material. On the other hand, a method for transferring a desired gap shape to the electrode substrate material by simultaneously performing isotropic and / or anisotropic etching on the photoresist layer and the electrode substrate has been proposed.
[0008]
Further, the following example is also presented as a specific example in which the photoresist layer is formed in the non-parallel gap shape. That is, after applying a photoresist on an electrode substrate (or an insulating film on the electrode substrate), using a photomask having a characteristic that scattered light is scattered, the central portion of the photomask is exposed on the exposed region of the photoresist layer. Then, the photoresist layer is exposed deeply and shallowly at the periphery of the photomask to form the non-parallel gap shape. Alternatively, the following example is also presented as another example of forming the non-parallel gap shape. In other words, once the photoresist has been opened, the photoresist is further applied in a stepped shape to form a photoresist layer with a smooth convex shape toward the diaphragm side at the periphery of the opening. Then, heat treatment is performed to form the photoresist layer smoothly. By simultaneously etching the photoresist layer and the electrode substrate having such a shape to transfer the shape of the resist layer to the electrode substrate, an electrode substrate having a highly flexible shape can be formed.
[0009]
Alternatively, the following method may be used as a method of manufacturing the electrode substrate that forms a gap shape non-parallel to the diaphragm.
A photoresist layer is formed on the electrode substrate (or a single insulating film formed on the electrode substrate), and then non-parallel to the photoresist layer by photolithography using a photomask in which the transmittance gradually changes. The photoresist layer and the electrode substrate material (or the insulating film on the electrode substrate) are simultaneously etched to transfer the non-parallel step shape formed on the photoresist layer to the electrode substrate material. Let
[0010]
In the electrostatic ink jet head, as described above, various gap structures are formed using various manufacturing methods to improve ink ejection performance and enable low voltage driving.
[0011]
[Problems to be solved by the invention]
However, it is difficult to accurately form the gap dimension formed between the diaphragm and the individual electrodes in a short time in the configurations and manufacturing methods of various conventional ink jet heads.
For example, in the above-mentioned Japanese Patent Application Laid-Open No. 6-071882, a single-layer SiO 2 is used as a gap spacer for securing the gap. ₂ Although it is disclosed that a film is used and the gap interval is set to 0.05 μm or more and 2.0 μm or less, a method for forming the gap interval dimension and a control means at the time of manufacturing related to the gap interval are not disclosed. In addition, as a material of the gap spacer, a single layer of SiO ₂ Since a film is used, the SiO ₂ Formation of the film requires a thermal oxidation treatment at a high temperature for a long time (for example, about 12 hours at 1100 ° C.).
[0012]
Japanese Patent Laid-Open No. 9-193375 discloses a configuration in which a non-parallel step is formed in an electrode substrate or a single silicon insulating film formed on the electrode substrate in order to form a non-parallel gap shape. It is not intended for multilayer / polycrystalline films. Further, since the control regarding the depth accuracy of the step for forming the non-parallel gap is performed by the etching rate ratio of the single insulating film and the photoresist or the etching rate and the etching time, the dimensional accuracy of the gap interval is related. , With the disadvantage that the variation tends to be large.
[0013]
[Means for Solving the Problems]
The present invention has been made in view of such problems, and has the following four objects.
A first object of the present invention relates to a material for a gap spacer and a method for forming the gap spacer. A conventional gap spacer material often uses a thermal oxide film, and forming a thermal oxide film having a thickness of 2 μm or more requires an oxidation process for a long time at a high temperature, resulting in an increase in manufacturing cost. In order to solve such a problem, the present invention reduces the manufacturing process time and the manufacturing cost by applying polysilicon, which has a higher film growth rate, as a gap spacer material than a single thermal oxide film. It is something to be done. As a future direction of electrostatic inkjet heads, in order to ensure high-speed and high-definition printing quality, the print bit cell is designed so that the discharge nozzle density can be improved with a constant ink droplet volume. There is also a direction to reduce the area, that is, the printed dot cell area as much as possible, and further to adjust the gap interval wide by making the diaphragm thinner, and the material and method for forming such a gap spacer are becoming more important. It is coming.
[0014]
The second object of the present invention relates to a manufacturing method for improving the dimensional accuracy of the gap interval. When forming the gap interval having a great influence on the driving voltage and the ink discharge amount in the electrostatic ink jet head, by stopping the etching of an oxide film or the like that also becomes a gap spacer material, The manufacturing process, such as determining the shape of the electrode substrate for forming the non-parallel gap shape, involves technical difficulties in terms of dimensional accuracy. In the present invention, it is an object of the present invention to provide a manufacturing method that stabilizes the gap interval dimension and reduces the variation of the interval dimension.
[0015]
The third object of the present invention is to provide a gap manufacturing method having a high degree of freedom with respect to the gap shape. In other words, low voltage drive is possible, multi-stage control of ink discharge amount is possible, and the electrostatic type that forms non-parallel gaps has advantages such as the ability to reduce variations in ink discharge amount and discharge speed An inkjet head can be manufactured, and furthermore, a manufacturing method capable of manufacturing such an electrostatic inkjet head at low cost, high reliability, high performance, and low variation is also provided.
[0016]
The fourth object of the present invention relates to the stability of the diaphragm potential. That is, by doping a polysilicon with impurities such as phosphorus or boron to make it conductive, and providing a manufacturing method using such a conductive polysilicon as a gap spacer, On the other hand, it is possible to obtain a stable potential from the electrode substrate side with no variation in diaphragm potential.
[0017]
Specifically, the following means for solving are provided. That is, according to the first aspect of the present invention, a diaphragm that forms part of a liquid chamber that communicates with a nozzle that ejects ink, and an individual electrode that is disposed to face the diaphragm through a gap are disposed. In an electrostatic ink jet head that performs recording on a recording medium by discharging ink from the liquid chamber from the nozzle by deforming the diaphragm by electrostatic force, the diaphragm and the individual substrate The main material of the gap spacer that forms the gap between the electrodes is formed of a polysilicon layer. , Doping the polysilicon layer with phosphorus, arsenic or boron It is characterized by being.
[0018]
According to a second aspect of the invention, in the first aspect of the invention, a silicon oxide film is formed between the polysilicon layer and the electrode substrate.
[0019]
According to a third aspect of the present invention, in the first or second aspect of the present invention, a polysilicon oxide film is formed on an upper surface and a side surface of the polysilicon layer.
[0020]
According to a fourth aspect of the present invention, in the first or second aspect of the invention, the policy Re A thermal CVD oxide film is formed on the upper surface and the side surface of the con layer.
[0022]
Claim 5 The invention includes a diaphragm that forms part of a liquid chamber that communicates with a nozzle that ejects ink, an electrode substrate on which an individual electrode that is disposed to face the diaphragm with a gap interposed therebetween, The electrostatic inkjet head according to claim 1, further comprising a gap spacer that forms the gap between the diaphragm and the individual electrode, wherein the gap spacer material is mainly formed of a polysilicon layer. In the manufacturing method, a step of forming the polysilicon layer on the electrode substrate using a CVD method, and forming a photoresist pattern having a shape corresponding to a desired shape of the individual electrode pattern on the polysilicon layer. Then, by etching the photoresist pattern, the shape of the photoresist pattern is transferred to the polysilicon layer to obtain a desired shape. A step of forming the polysilicon layer And forming the polysilicon layer, and then doping phosphorus, arsenic, or boron on the upper surface of the polysilicon layer and doping the polysilicon layer with phosphorus, arsenic, or boron; It is characterized by having.
[0023]
Claim 6 The invention of claim 5 In the invention, prior to the step of forming the polysilicon layer on the electrode substrate, the step of subjecting the electrode substrate to a thermal oxidation process to form a thin silicon oxide film on the electrode substrate; and the silicon oxide film Forming a polysilicon layer on the polysilicon layer by a CVD method; and forming a photoresist pattern having a shape corresponding to a desired shape of the individual electrode pattern on the polysilicon layer; and etching the photoresist pattern To transfer the shape of the photoresist pattern to the polysilicon layer to form the polysilicon layer having a desired shape.
[0024]
Claim 7 The invention of claim 5 Or 6 In the present invention, the method includes a step of forming a thin polysilicon oxide film on an upper surface and a side surface of the polysilicon layer by performing thermal oxidation after forming the polysilicon layer having a desired shape. Is.
[0025]
Claim 8 The invention of claim 5 Or 6 In the present invention, after the formation of the polysilicon layer having a desired shape, a thin thermal CVD oxide film is formed on the upper surface and side surfaces of the polysilicon layer by a CVD method.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
A configuration of an electrostatic ink jet head according to the present invention and a method for manufacturing the ink jet head will be described below with reference to the drawings.
Each figure shows only one print bit cell (that is, print dot cell) for the sake of simplicity, but in practice, a plurality of print bit cells (print dot cells) are equal on the same substrate. The electrostatic ink jet head is formed at intervals.
First, a first embodiment of an electrostatic ink jet head according to the present invention will be described with reference to FIGS. 1 and 2.
[0028]
FIG. 1 is a cross-sectional view showing a main part of an actuator part relating to an electrostatic ink jet head according to the present invention.
In FIG. 1, reference numeral 210 denotes an electrode substrate serving as a support substrate for disposing the individual electrodes 250. The electrode substrate 210 is opposed to the diaphragm 120 through a gap 300 having a minute width and is covered with an insulating film 260. The electrodes, that is, the individual electrodes 250 are attached to the substrate 100 constituting the diaphragm 120 by direct bonding or the like. Here, a minute gap 300 is formed between the diaphragm 120 and the individual electrode 250 (precisely, the insulating film 260 formed on the individual electrode 250) disposed at a position facing the diaphragm 120. Therefore, when a voltage is applied between the individual electrode 250 and the diaphragm 120, the diaphragm 120 is displaced to the individual electrode 250 side by an electrostatic force. When the applied voltage is restored to the original 0 level, the ink is recorded through the nozzle 10 connected from the liquid chamber 150 by the force of the displaced diaphragm 120 to return to the original position by the elastic force. It is discharged toward the surface.
[0029]
In addition, a polysilicon layer 220 is formed on the electrode substrate 210 as a gap spacer for ensuring a gap interval between the diaphragm 120 and the individual electrode 250. Together with the polysilicon oxide film 230 and the silicon oxide film 240, The polysilicon layer 220 is formed such that the dimensional accuracy of each film thickness is controlled within a certain dimensional error. A method for forming the polysilicon layer 220 and the polysilicon oxide film 230 will be described in detail later.
[0030]
Note that the present invention relates to a method of forming a gap between the diaphragm 120 and the individual electrode 250 facing each other with the gap 300 interposed therebetween, and other components are not shown in FIG. In the same manner as described above, an electrostatic ink jet head is manufactured by assembling components such as an ink supply path and a fluid resistance to the actuator portion having the configuration shown in FIG.
[0031]
Further, in the electrostatic ink jet head shown in FIG. 1, from one end of the individual electrode 250 to the center of the individual electrode 250 for the purpose of lowering the drive voltage and controlling the number of ejected ink droplets in multiple steps. Accordingly, the individual electrode 250 is formed in a shape non-parallel to the diaphragm 120 so that the gap 300 between the diaphragm 120 and the diaphragm 120 at a position facing the individual electrode 250 gradually increases. In the remaining portion, the individual electrode 250 has a shape bent at the center so that the gap shape with the diaphragm 120 is parallel. The insulating film 260 on the individual electrode 250 is for preventing a short circuit between the individual electrode 250 and the diaphragm 120 when the diaphragm 120 is displaced. The insulating film 260 is formed on the diaphragm 120 side. However, the same effect can be achieved. In addition, the insulating film 260 can be omitted when the diaphragm 120 and the individual electrode 250 are operated by a driving method in which the diaphragm 120 and the individual electrode 250 are not in direct contact.
[0032]
Note that the shape of the gap 300 formed using the above-described bent individual electrodes 250 is merely an example, and other gap shapes may be used according to the purpose.
Furthermore, as will be described later, a silicon oxide film may be formed between the polysilicon layer 220 and the electrode substrate 210.
[0033]
Next, a manufacturing method of the electrostatic ink jet head according to the present invention will be described with reference to a manufacturing process step diagram shown in FIG. Here, FIG. 2 shows a process of manufacturing the main part of the actuator part of the electrostatic ink jet head. The actuator part manufactured in the process is subjected to an ink supply path, As described above, the electrostatic ink jet head can be manufactured by assembling the fluid resistance, the nozzle plate and the like.
[0034]
In FIG. 2, first, a polysilicon layer 220 that forms a gap spacer on an electrode substrate 210 made of a silicon wafer having a crystal axis <100> containing phosphorus or boron in an amount of 0.01 to 0.1 Ω · cm. A film is formed to a thickness of 1 μm by the CVD method (FIG. 2A).
[0035]
Next, after forming a photoresist pattern having a shape corresponding to the shape of the formation area of the desired individual electrode pattern on the polysilicon layer 220, a silicon etchant (that is, a solution of hydrofluoric acid: nitric acid = 1: 100) is added. Wet etching is used. When single crystal silicon is used for the electrode substrate 210, the etching rate is different when the etching reaches the interface between the polysilicon layer 220 and the electrode substrate 210 due to the difference in the etching rate between the polysilicon layer 220 and the single crystal silicon. Since it is abruptly delayed, the wet etching is terminated at this point, and the photoresist is removed (FIG. 2B). That is, in this embodiment, desired etching is performed by etching time management, and etching is stopped at a position where a desired gap interval can be secured.
[0036]
Further, the entire electrode substrate 210 having the polysilicon layer 220 is oxidized, and a silicon oxide film 240 that becomes an insulating layer with respect to the electrode substrate 210 is formed on the electrode substrate 210 when the individual electrodes are formed. A polysilicon oxide film 230 serving as an insulating film is formed with a thickness of 0.5 μm on the upper and side surfaces (FIG. 2C).
[0037]
Next, an individual electrode material (TiN or the like) is formed by bending on the silicon oxide film 240, and then patterned into the shape of the individual electrode 250. Further, in order to protect the individual electrode 250, the individual electrode 250 Then, an insulating film 260 is formed and patterned. If the individual electrode material is TiN, the shape of the individual electrode 250 can be etched with ammonia water (added with hydrogen peroxide solution) (FIG. 2D).
[0038]
The substrate 100 of the silicon wafer that forms the vibration plate 120 is attached to the electrode substrate 210 having the individual electrode 250 and the insulating film 260 and having the polysilicon layer 220 and the polysilicon oxide film 230 by direct bonding or the like. Then, the substrate 100 is etched to form a portion that becomes the ink liquid chamber 150. Here, the etching is stopped when the thickness of the diaphragm 120 constituting the bottom surface of the liquid chamber 150 becomes 1 to 3 μm (FIG. 2E).
[0039]
Furthermore, since the present invention relates to a gap forming method between the diaphragm 120 and the individual electrode 250 with the gap 300 interposed therebetween, assembly of other parts is not shown, but an ink supply path, fluid resistance, etc. Then, as shown in FIG. 1, the nozzle plate 50 having the nozzles 10 is joined to the partition walls 110 constituting the substrate 100 by using a manufacturing method similar to that of the conventional type. An ink jet head is formed.
[0040]
As a future direction, there is a direction in which the gap interval 300 is adjusted to be wide as described above in order to improve the ink droplet ejection performance, and the film thickness of the gap spacer is increased in response to the increase in the gap 300 interval. Must. Therefore, when a silicon oxide film is used as a material for the gap spacer as in the prior art, the thickness of the silicon oxide film must be increased. In order to form a silicon oxide film with a thickness of 1.5 μm, however, Oxidation time is required for about 12 hours in a high temperature oxidation environment of 1100 ° C. On the other hand, in the case of using polysilicon, in order to obtain the same gap shape, a polysilicon film having a thickness of 1.2 μm is formed for about 6 hours, and an oxide film serving as an insulating film is formed with a thickness of 0.3 μm. Can be formed in a total of 8 hours. Therefore, the manufacturing period can be shortened and the total manufacturing cost can be reduced.
[0041]
Since the wet etching rate is significantly different between the polysilicon layer 220 and the single crystal silicon of the electrode substrate 210 as described above, only the polysilicon layer 220 can be etched almost selectively. Therefore, the height of the gap spacer for defining the gap 300 is substantially determined by the thickness of the polysilicon layer 220. Even after the oxide films 230 and 240 in the next process are formed, the height of the gap spacer is substantially the same as the height of the gap spacer. The thickness of the silicon film 220 remains as it is. That is, when the substrate 100 constituting the vibration plate 120 is bonded to form the gap 300, the gap 300 is spaced from the thickness of the polysilicon layer 220 to protect the individual electrode 250 and the individual electrode 250. The thickness of the insulating film 260 is subtracted, and the gap 300 can be accurately and quickly formed.
[0042]
Next, a second embodiment of the electrostatic inkjet head according to the present invention will be described based on the manufacturing process step diagram of FIG. The present embodiment is substantially the same as the first embodiment described above, but before forming the polysilicon layer 220 on the electrode substrate 210, first, the silicon oxide film 270 is formed thinly on the electrode substrate 210. Is different. Hereinafter, characteristic points different from the first embodiment in the manufacturing process steps will be described with reference to FIG.
[0043]
First, the electrode substrate 210 made of a silicon wafer is thermally oxidized in an oxygen atmosphere at 1000 ° C. to form a silicon oxide film 270 having a very thin film thickness of about 100 mm on the electrode substrate 210. Thereafter, a polysilicon layer 220 having a thickness of 1 μm is formed on the silicon oxide film 270 by CVD (FIG. 3A).
[0044]
Next, in order to form a shape corresponding to the shape of a desired individual electrode pattern on the polysilicon layer 220, a photoresist layer 280 is formed on the polysilicon layer 220, and the photoresist layer 280 is formed by photolithography. A shape corresponding to a desired individual electrode pattern shape is formed (FIG. 3B).
Here, the case where the shape of the individual electrode pattern is a bent shape bent at the center as shown in FIG. 1 is shown.
[0045]
As another method for forming such a shape, a photomask in which the aperture ratio is changed according to the shape to change the light transmittance can be used. When using such a photomask, first, as described above, after forming a photoresist layer on the polysilicon layer 220 by spin coating, the photoresist layer is exposed and developed using the photomask. By doing so, a photoresist layer having a desired shape can be formed.
[0046]
Next, when the photoresist layer 280 and the polysilicon layer 220 are etched simultaneously in the depth direction by an isotropic and / or anisotropic dry etching method, the photoresist layer 280 is formed in accordance with the progress of the etching. The bent shape is transferred to the polysilicon layer 220. In this embodiment, CF is used as an etching gas. _Four , O ₂ The mixed gas system plasma is used.
[0047]
In addition, by monitoring plasma emission during dry etching, etching can be stopped at an accurate etching depth. That is, since the silicon oxide film 270 is formed on the lower surface of the polysilicon layer 220 in advance, when the etching proceeds, the polysilicon layer 220 disappears and the underlying silicon oxide film 270 is exposed, the wavelength intensity of plasma emission If the light having the intensity of the light emission wavelength inherent to silicon is detected, the polysilicon layer 220 is eliminated and the underlying silicon oxide film is exposed, and etching may be stopped. By using such an etching stop, it is possible to accurately control the gap 300 between the individual electrode 250 shown in FIG. If it is strong, the printing characteristic of each printing dot can be made uniform. When the etching is stopped, the photoresist layer 280 is removed, whereby an electrode substrate 210 having a bent polysilicon layer is obtained (FIG. 3C).
[0048]
After forming the polysilicon layer 220 having a bent shape corresponding to the shape of the individual electrode pattern, the same steps as those in FIGS. 2C to 2E shown in the first embodiment are performed. Thereby, the actuator part of an inkjet head can be comprised. That is, first, by oxidizing the entire electrode substrate 210 on which the bent polysilicon layer 220 is formed, the silicon oxide film 240 serving as an insulating film layer with the electrode substrate 210 is formed in the electrode substrate when the individual electrode 250 is formed. A polysilicon oxide film 230 is formed on the upper surface and side surfaces of the polysilicon layer 220 as well as an insulating film (FIG. 3D).
[0049]
Next, an individual electrode material is folded and formed on the upper surface of the silicon oxide film 240 and the inclined surface of the polysilicon oxide film 230, followed by patterning into the shape of the individual electrode 250 having a bent shape. In order to protect, an insulating film 260 is formed over the individual electrode 250 and patterned (FIG. 3E).
[0050]
After the silicon wafer substrate 100 constituting the vibration plate 120 is attached to the electrode substrate 210 on which the individual electrode 250 is formed by direct bonding or the like, the substrate 100 is etched to form the liquid chamber 150, and the liquid chamber The thickness of the diaphragm 120 at the bottom of the substrate is 1 to 3 μm (FIG. 3F).
[0051]
The gap 300 between the individual electrode 250 and the diaphragm 120 formed by bonding the electrode substrate 210 and the substrate 100 is the polysilicon layer 220 that forms the gap spacer, as in the first embodiment. It is mainly controlled by the film thickness. Therefore, as described above, if the dry etching depth is stopped by monitoring the plasma emission, the accurate film thickness of the polysilicon layer 220 can be obtained, so that a desired gap interval can be realized with high accuracy. Become.
[0052]
Next, a third embodiment of the electrostatic inkjet head according to the present invention will be described with reference to FIG.
FIG. 4 is a cross-sectional view showing the main part of the actuator part relating to the electrostatic ink jet head.
That is, in the first and second embodiments described above, a thermal oxide film (more precisely, the polysilicon layer 220 is formed on the electrode substrate 210 having the polysilicon layer 220 having a shape corresponding to the shape of the individual electrode pattern. A polysilicon oxide film 230 and a silicon oxide film 240) are formed on the upper and side surfaces, and on the electrode substrate 210. In this embodiment, instead of the thermal oxide film, a high temperature of 0.5 .mu.m is formed. An oxide film 295 is formed.
Here, the high temperature oxide film is a thermal CVD oxide film formed at a high temperature of 600 ° C. or higher by an LPCVD apparatus, that is, an HTO (High-Temperature-Oxide) film. Compared with a film, the folding rate is high, and a desired film thickness can be obtained in a short time.
[0053]
The film thickness of the thermal CVD oxide film, which is the high temperature oxide film 295, is formed to the same thickness (0.5 μm thickness) on the polysilicon layer 220 and the electrode substrate 210. Similar to the case of the first and second embodiments, the film thickness is approximately the thickness of the polysilicon layer 220. Accordingly, as in the first and second embodiments described above, the gap 300 between the individual electrode 250 and the diaphragm 120 is formed by accurately controlling the film thickness of the polysilicon layer 220. Can be formed with high accuracy.
[0054]
Also for the manufacturing method of the high-temperature oxide film 295, the electrode substrate 210 having the polysilicon layer 220 is formed at 600 ° C. by the CVD method instead of the entire oxidation process of FIG. 2C showing the manufacturing process in the first embodiment. The manufacturing process in the first embodiment is the same as that in the first embodiment except that the oxidation process is performed at the above high temperature and the thermal CVD oxide film having a thickness of 0.5 μm is formed.
[0055]
Next, a fourth embodiment of the electrostatic inkjet head according to the present invention will be described with reference to FIG.
FIG. 5 is a cross-sectional view showing a main part of an actuator part relating to the electrostatic ink jet head.
First, the crystal axis <100> silicon wafer used as the electrode substrate 210 is one containing phosphorus, arsenic, or boron containing 0.01 to 0.1 Ω · cm. A polysilicon layer 225 patterned in accordance with the pattern shape of the individual electrode 250 is formed on the electrode substrate 210. Phosphorus, arsenic, or boron has a sheet resistance value of 5 to 40Ω / □ on the polysilicon layer 225. Since it is doped at a concentration that is about a level, it is a polysilicon layer having conductivity.
Further, both the substrate 100 and the electrode substrate 210 constituting the vibration plate 120 have the same contact area with respect to the polysilicon layer 220 over all print dots.
Therefore, the potential of the diaphragm 120 can be obtained from the electrode substrate side 210 side with the same low resistance value for all the printing dots, and the potential of the diaphragm 120 can be stabilized. In addition, since it is not necessary to provide a special electrode terminal on the substrate 100 side on which the diaphragm 120 is formed, the degree of freedom of electrical wiring is increased, and a favorable effect can be provided for the design and manufacturing process.
[0056]
A method for manufacturing such an electrostatic inkjet head will be described below with reference to FIG.
First, a polysilicon layer 220 is deposited to a thickness of 1 μm on the entire surface of the electrode substrate 210, which is a silicon wafer containing 0.01 to 0.1 Ω · cm of phosphorus, arsenic, or boron with a crystal axis <100>. And is formed into a film (FIG. 6A).
[0057]
Next, as in the case of the second embodiment, a photoresist pattern is formed on the polysilicon layer 220 and then CF is used as an etching gas. _Four And O ₂ Isotropic and / or anisotropic dry etching is performed using a mixed gas-based plasma and the polysilicon layer 220 is patterned into a shape corresponding to the individual electrode pattern shape. Here, as shown in the second embodiment, the polysilicon layer 220 may have a non-parallel gap shape. After the patterning is completed, the photoresist is removed (FIG. 6B).
[0058]
Next, phosphorus is bent from the upper surface of the polysilicon layer 220, and then phosphor glass etching is performed using hydrofluoric acid. A conductive polysilicon layer 225 having a low resistance property doped with phosphorus is formed in the polysilicon layer 220 (FIG. 6C). The sheet resistance value is measured using a single crystal silicon monitor, and the concentration of doped phosphorus is controlled to be 5 to 40Ω / □. Further, even if arsenic is doped in the polysilicon layer 220 instead of phosphorus, the ohmic characteristics can be given to the polysilicon layer 220 in the same manner. If the electrode substrate 210 is P-type silicon and the substrate 100 constituting the diaphragm 120 is also P-type silicon, boron is folded and the polysilicon layer 220 is doped with boron to form a polysilicon layer. 220 may be a conductive polysilicon layer 225 having an electrically low resistance ohmic characteristic.
[0059]
Thereafter, the entire electrode substrate 210 on which the conductive polysilicon layer 225 having low resistance ohmic characteristics is formed is oxidized, and a polysilicon oxide film 235 is formed on the upper surface and side surfaces of the conductive polysilicon layer 225 on the electrode substrate 210. A silicon oxide film 245 is formed to a thickness of 0.5 μm (FIG. 6D).
Since both the conductive polysilicon layer 225 and the electrode substrate 210 are silicon oxide films containing phosphorus, the oxidation proceeds at an increased speed. However, the conductive polysilicon layer 225 and the electrode substrate 210 are approximately the same. Since the concentration of phosphorus is doped, the polysilicon oxide film 235 and the thermal silicon oxide film 245 have substantially the same thickness.
[0060]
Next, after an electrode material (TiN or the like) is folded on the silicon oxide film 245, patterning is performed on the shape of the individual electrode 250. Further, in order to protect the individual electrode 250, the insulating film 260 is formed on the individual electrode 250. After film formation, patterning is performed.
Thereafter, the polysilicon oxide film 235 formed on the upper surface of the conductive polysilicon layer 225 is removed with a photoresist (FIG. 6E).
[0061]
Next, after the silicon substrate 100 constituting the vibration plate 120 is attached to the conductive polysilicon layer 225 by direct bonding or the like, the substrate 100 is etched to form a portion that becomes the liquid chamber 150. Here, the thickness of the diaphragm 120 constituting the bottom surface of the liquid chamber 150 is controlled to be stopped when the thickness becomes 1 to 3 μm (FIG. 6F).
Note that the silicon substrate 100 constituting the vibration plate 120 has a resistance value of 0.01 to 0.1 Ω · cm, similarly to the electrode substrate 210.
[0062]
【The invention's effect】
Effects of (Claim 1) and (Claim 6)
Since the polysilicon layer is used as the material of the gap spacer, the etching depth of the polysilicon layer that constitutes the height of the gap spacer by utilizing the fact that the wet etching rate is significantly different from the single crystal silicon forming the electrode substrate Therefore, it is possible to improve the dimensional accuracy of the gap between the diaphragm and the individual electrode, and to increase the yield in manufacturing the electrostatic ink jet head. In addition, it is possible to achieve high printing quality with little variation in the size and position of the printing dots of the electrostatic inkjet head.
[0063]
Effects of (Claim 2) and (Claim 7)
Since the silicon oxide film is formed under the polysilicon layer, when dry etching is performed in order to form a polysilicon layer having an inclined shape corresponding to the shape of the individual electrode non-parallel to the diaphragm, When the silicon oxide film under the polysilicon layer is exposed, the etching can be stopped by detecting light having the intrinsic emission wavelength intensity of silicon. Therefore, since the etching depth of the polysilicon layer can be controlled with high accuracy, the same effects as in (Claim 1) and (Claim 6) can be obtained. In addition, the degree of freedom of the individual electrode shape is increased, and the formation of a non-parallel gap with the diaphragm becomes easier, so that low voltage driving of the electrostatic inkjet head can be realized.
[0064]
(Claim 3), (Claim 4), (Claim 8) and (Claim 9)
Since electrical insulation between the polysilicon layer, which is a gap spacer, and the individual electrodes can be obtained, electrically stable high-quality diaphragm driving can be performed. In addition, since an oxide film having the same thickness as the polysilicon oxide film or the thermal CVD oxide film formed on the upper surface of the polysilicon layer can be formed under the individual electrodes, the gap distance between the diaphragm and the individual electrodes can be formed. Can be controlled mainly by the height of the gap spacer of the polysilicon layer, and the same effects as in (Claim 1) and (Claim 6) can be obtained.
[0065]
Effects of (Claim 5) and (Claim 10)
By doping the polysilicon layer with phosphorus, arsenic, or boron, a low-resistance conductive polysilicon layer can be obtained, so that electrical connection between the diaphragm and the electrode substrate is possible, and the potential of the diaphragm is completely reduced. It can be obtained by utilizing the back surface of the electrode substrate over the printed dots. Therefore, it is not necessary to provide a special electrode terminal on the substrate constituting the diaphragm, the degree of freedom of electrical wiring is increased, and a favorable effect on the design and manufacturing process can be obtained. Further, since the potential of the diaphragm can be obtained from the electrode substrate side through the same low resistance value for all the printing dots, the potential of the diaphragm can be stabilized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of a main part of an actuator part related to an electrostatic ink jet head according to the present invention.
FIG. 2 is a manufacturing process step diagram for illustrating a first embodiment of a manufacturing step of an actuator section related to an electrostatic ink jet head according to the present invention.
FIG. 3 is a manufacturing process step diagram for illustrating a second embodiment of a manufacturing step of an actuator section related to the electrostatic ink jet head according to the present invention.
FIG. 4 is a cross-sectional view showing a third embodiment of the main part of the actuator part related to the electrostatic inkjet head according to the present invention.
FIG. 5 is a cross-sectional view showing a fourth embodiment of the main part of the actuator part related to the electrostatic inkjet head according to the present invention.
FIG. 6 is a manufacturing process step diagram for illustrating a fourth embodiment of a manufacturing step of an actuator portion related to the electrostatic ink jet head according to the present invention.
FIG. 7 is a diagram showing a configuration of a conventional electrostatic inkjet head.
FIG. 8 is a diagram illustrating another configuration of a conventional electrostatic inkjet head.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Nozzle, 50 ... Nozzle plate, 100 ... Substrate, 110 ... Partition, 120 ... Vibration plate, 150 ... Liquid chamber, 210 ... Electrode substrate, 220 ... Polysilicon layer, 225 ... Conductive polysilicon layer, 230, 235 ... Polysilicon oxide film, 240, 245 ... Silicon oxide film, 250 ... Individual electrode, 260 ... Insulating film, 270 ... Silicon oxide film, 280 ... Photoresist layer, 295 ... High temperature oxide film (thermal CVD oxide film), 300 ... Gap , 301 ... (first) substrate, 302 ... electrode substrate, 304 ... nozzle hole, 305 ... diaphragm, 306 ... liquid chamber, 321 ... individual electrode, 402 ... (first) substrate, 404 ... electrode substrate (glass) Substrate), 405 ... liquid chamber, 410 ... individual electrode, 411 ... nozzle hole, 415 ... insulating film, 451 ... diaphragm.

Claims (8)

A diaphragm that constitutes a part of a liquid chamber that communicates with a nozzle that ejects ink, and an electrode substrate on which an individual electrode that is disposed to face the diaphragm through a gap is disposed, Forming the gap between the diaphragm and the individual electrode in an electrostatic ink jet head that records on a recording medium by ejecting ink in the liquid chamber from the nozzle by deforming the diaphragm by electrostatic force the main material of the gap spacer cell is formed of a polysilicon layer, the electrostatic ink jet head, characterized in that it is doped with phosphorus or arsenic or boron into the polysilicon layer.   2. The electrostatic ink jet head according to claim 1, wherein a silicon oxide film is formed between the polysilicon layer and the electrode substrate.   3. The electrostatic ink-jet head according to claim 1, wherein a polysilicon oxide film is formed on an upper surface and a side surface of the polysilicon layer. In the electrostatic type ink jet head according to claim 1 or 2, wherein the electrostatic ink jet head, characterized in that on the top and sides of the policy Li Gong layer thermal CVD oxide film is formed. A diaphragm that forms part of a liquid chamber that communicates with a nozzle that ejects ink; an electrode substrate on which an individual electrode that is disposed to face the diaphragm through a gap; and the diaphragm, 2. The method of manufacturing an electrostatic inkjet head according to claim 1, further comprising: a gap spacer that forms the gap between the individual electrodes, wherein the gap spacer material is mainly formed of a polysilicon layer. Forming the polysilicon layer on the electrode substrate using a CVD method, and forming a photoresist pattern having a shape corresponding to a desired shape of the individual electrode pattern on the polysilicon layer; By etching the photoresist pattern, the shape of the photoresist pattern is transferred to the polysilicon layer, and the desired shape of the polysilicon layer is transferred. A step of forming the silicon layer, after forming the polysilicon layer, and phosphorus or arsenic or boron so out folding the upper surface of the polysilicon layer, is doped with the phosphorus or arsenic or boron into the polysilicon layer method for manufacturing an electrostatic type ink jet head, characterized by a step. 6. The method of manufacturing an electrostatic ink jet head according to claim 5 , wherein prior to the step of forming the polysilicon layer on the electrode substrate, the electrode substrate is subjected to a thermal oxidation treatment to form thin silicon on the electrode substrate. A step of forming an oxide film, a step of forming the polysilicon layer on the silicon oxide film by a CVD method, and a photoresist pattern having a shape corresponding to a desired shape of the individual electrode pattern on the polysilicon layer And forming the polysilicon layer having a desired shape by transferring the shape of the photoresist pattern to the polysilicon layer by etching the photoresist pattern. A manufacturing method of an electrostatic ink jet head characterized by the above. In the manufacturing method of the electrostatic type ink jet head according to claim 5 or 6, after forming the polysilicon layer having a desired shape, by performing thermal oxidation treatment, a thin upper and side surfaces of the polysilicon layer A method for manufacturing an electrostatic ink jet head, comprising a step of forming a polysilicon oxide film. In the manufacturing method of the electrostatic type ink jet head according to claim 5 or 6, after forming the polysilicon layer having a desired shape, the thin thermal CVD oxide film on the upper surface and the side surface of the polysilicon layer by the CVD method A method of manufacturing an electrostatic ink jet head, comprising a step of forming the electrostatic ink jet head.

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