JPH08276615A - Charge generation control element for electrostatic image forming apparatus and production thereof - Google Patents

Abstract

PURPOSE: To enhance the durability of a charge generation control element by forming a first insulating film item a plurality of layers set so that a refractive index becomes high successively from a bottom layer to a surface layer and setting the bottom layer low in refractive index to thickness capable of obtaining predetermined withstand voltage. CONSTITUTION: A charge generation control element consists of the line electrode 2 formed on an insulating substrate 1, the first insulating film 3 formed on the line electrode 2, the finger electrode 4 formed on the first insulating film 3 and having a charge forming hole part 7 at the center part thereof and the screen electrode 6 formed on the surface of the finger electrode 4 through a second insulating film 5 having a charge passing hole part at the center part thereof and having a charge outflow hole part 8 at the center part thereof. The first insulating film 3 consists of a bottom layer 3-1 low in refractive index and formed so as to have predetermined thickness obtaining desired insulating withstand voltage, the intermediate layer 3-2 formed on the layer 3-1 and formed from silicon nitride having a refractive index higher than that of the bottom layer 3-l and a surface layer 3-3 made of silicon nitride having a refractive index higher than that of the intermediate layer 3-2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge generation control element for an electrostatic image forming apparatus used for electrostatic printing and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a charge generation control element utilizing corona discharge has been used as a method for forming a latent image by electrostatic charges on a dielectric recording body by the principle of transferring charges directly onto the dielectric recording body and depositing them. Is disclosed in Japanese Patent Publication No. 2-62862, and such a charge generation control element is
A method of forming with high precision using semiconductor microfabrication technology is
It is proposed in Japanese Patent Application No. 6-288580, which is the application of the present applicant.

FIG. 7 is a sectional view showing a part of a configuration example of a conventional charge generator for an electrostatic image forming apparatus. In FIG. 7, 100 indicates one charge generation control element, and the charge generator is configured by arranging a large number of charge generation control elements 100 one-dimensionally or two-dimensionally. The charge generation control element 100 is a substrate 101 made of quartz or glass.
A line electrode 102 made of metal, and a first insulating film 103.
And a finger electrode 104 made of metal and a second insulating film
105 and a screen electrode 106, and finger holes 107 and 108 are formed in the finger electrode 104 and the screen electrode 106, respectively.

Then, the charge generation control element 100 having the above structure
Each of the electrodes constituting is formed by forming a resist pattern on the metal film formed by a method such as a sputtering method or a vacuum deposition method, and then removing the portion not covered by the resist pattern by etching. The first insulating film 103 is a silicon oxide film or a silicon nitride film formed by a method such as a CVD (Chemical Vapor Deposition) method or a sputtering method, or a film having an intermediate property between both insulating films. A material having a high electrostatic withstand voltage is used. A resin having high heat resistance such as polyimide is used for the second insulating film 105.

Next, the operation of the charge generation control element 100 thus constructed will be described. In FIG.
By applying an AC voltage between the line electrode 102 and the finger electrode 104 which are arranged with the first insulating film 103 sandwiched between them, the side wall of the finger hole 107 and the upper part of the first insulating film 103 are affected by a corona discharge phenomenon. A charge group is generated. Negative charges having high mobility in this charge group are used for latent image formation. A second insulating film facing the finger electrode 104.
When the screen electrode 106 formed by interposing 105 is applied with a positive potential higher than the potential applied to the finger electrode 104, the negative charge generated by the corona discharge is extracted from the screen hole 108 formed in the screen electrode 106. It The negative charges extracted from the screen holes 108 are accelerated toward a drum (not shown), which is a dielectric recording body, and are deposited on the drum to form a latent charge image. Conversely, when a negative potential is applied to the screen electrode 106 with respect to the finger electrode 104, extraction of negative charges from the screen hole 108 is blocked, and a latent image is not formed on the drum.

[0006]

When driving the conventional charge generation control element shown in FIG. 7, an electric field of several MV / cm is generated inside the first insulating film 103, and
The surface of the first insulating film 103 is exposed to the plasma generated by the corona discharge, which causes a problem that the surface layer is scraped as indicated by reference numeral 109. Therefore, from the viewpoint of improving reliability, it is necessary to increase the film thickness of the first insulating film 103 or to form a hard insulating film that can withstand corona discharge.

However, if the first insulating film is formed of a hard insulating film that can withstand corona discharge without limitation, it takes a long time to form the insulating film and process the insulating film, and cracks (cracks) due to film stress. 110, the warp of the insulating substrate 101, and problems such as an increase in discharge starting voltage occur.

The present invention has been made to solve the above problems in the conventional charge generation control element. The invention according to claim 1 provides the first insulating film with a predetermined withstand voltage and durability. It is an object of the present invention to provide a charge generation control element capable of improving The invention according to claim 2 aims to provide a material suitable for the first insulating film having high durability. The invention according to claim 3 is the invention according to claim 2.
It is an object of the present invention to provide a manufacturing method for forming an insulating layer made of a highly durable material. It is an object of the present invention to provide a charge generation control element including a thick first insulating film that does not cause cracks in the first insulating film or warpage of the substrate.

[0009]

In order to solve the above problems, the invention according to claim 1 provides a line electrode formed on an insulating substrate and a first electrode formed on the surface of the line electrode. An insulating film, a finger electrode formed on the first insulating film and having a hole for charge generation in the center, and a second hole having a hole for allowing charges to pass through in the center of the finger electrode surface. In the charge generation control element comprising a screen electrode having a hole for discharging charges in the central portion formed through the insulating film, the first insulating film is composed of a plurality of layers, the bottom layer to the surface layer. The bottom layer having a low refractive index is set to have such a thickness that a predetermined withstand voltage can be obtained. In this way, by setting the refractive index sequentially higher from the bottom layer toward the surface layer, a hard surface layer that withstands corona discharge can be obtained,
Further, since the bottom layer having a low refractive index is set to have a thickness capable of obtaining a predetermined withstand voltage, a charge generation control element having a first insulating film having a predetermined withstand voltage and capable of improving durability. Can be realized.

According to a second aspect of the present invention, in the charge generation control element according to the first aspect, the surface layer of the first insulating film is composed of a silicon-rich silicon nitride layer having a refractive index of 2.3 or more. is there. As a result, a charge generation control element having a first insulating film having a surface layer made of a hard and dense material having high durability can be obtained.

According to a third aspect of the present invention, the silicon nitride layer forming the surface layer of the first insulating film of the charge generation control element according to the second aspect is formed by a reaction of monosilane and nitrogen by a plasma CVD method. Is. This makes it possible to easily manufacture the first insulating film having a highly durable surface layer.

According to a fourth aspect of the present invention, a line electrode formed on an insulating substrate, a first insulating film formed on the surface of the line electrode, and an upper portion of the first insulating film are formed. A finger electrode having a hole portion for charge generation in the center portion and a second insulating film having a hole portion for allowing the passage of charges in the center portion formed on the surface of the finger electrode, through which the charge flows out to the center portion. In the charge generation control element comprising a screen electrode having a hole portion, the first insulating film is formed by alternately laminating an insulating layer having a large compressive stress characteristic and an insulating layer having a large tensile stress characteristic. To form. Accordingly, it is possible to realize a charge generation control element including a thick first insulating film that has durability and can obtain a predetermined breakdown voltage without causing a crack in the insulating film or a warp of the substrate.

[0013]

EXAMPLES Next, examples will be described. 1 is a sectional view showing a first embodiment of a charge generation control element for an electrostatic image forming apparatus according to the present invention. In the figure, 1 is an insulating substrate made of quartz or glass, and 2 is a line electrode made of metal formed on the insulating substrate 1. 3-1 is a bottom layer made of low-refractive-index silicon oxide formed on the surfaces of the insulating substrate 1 and the line electrode 2 and formed to a predetermined thickness so that a desired withstand voltage can be obtained. 3-2 is the bottom layer. The intermediate layer 3-3 formed on the layer 3-1 and having a refractive index higher than that of silicon oxide is made of silicon nitride, and the intermediate layer 3-3 formed on the intermediate layer 3-2 is made of silicon nitride having a higher refractive index than the intermediate layer. In the surface layer, the bottom layer 3-1, the intermediate layer 3-2 and the surface layer 3-3 form the first insulating film 3. 4 is the first
Is a finger electrode having a finger hole 7 formed in the center of the insulating film 3 of FIG. Reference numeral 5 is a second insulating film formed in the surface of the finger electrode 4 and having a hole for passing charges in the center, and 6 is a screen hole for discharging charges in the center formed in the surface of the second insulating film 5. 8 is a screen electrode.

In the charge generation control element thus constructed, the surface layer 3-3 made of silicon nitride having a high refractive index is formed on the surface of the first insulating film 3 in the finger hole 7. Plasma CVD shown in FIG.
As can be seen from the characteristic diagram showing the relationship between the refractive index n of the insulating film formed by the method, the film hardness and the wet etching rate, the surface layer 3-3 having a high refractive index is dense and has a high hardness. It is possible to prevent film loss due to corona discharge that occurs within 7, and to provide excellent durability. Further, since the bottom layer 3-1 is formed to have a predetermined thickness capable of obtaining a desired withstand voltage, a charge generation control element including a first insulating film having a desired withstand voltage and durability is realized. be able to.

Next, a first embodiment of the method of manufacturing the charge generation control element according to the present invention will be described with reference to the manufacturing process diagrams shown in FIGS. First, as shown in FIG.
An aluminum film 12-1 having a thickness of about 0.5 μm and a titanium film 12-2 having a thickness of about 0.3 μm are formed on a quartz (glass) substrate 11.
And are successively and sequentially formed in the sputtering apparatus.
At this time, the titanium film 12-2 acts as a hillock (projection) prevention film from the aluminum film 12-1 by heat treatment or the like. Next, as shown in FIG. 3B, a resist pattern 13 is formed, and the aluminum film 12-1 and titanium film 12-2 portions not covered with the resist pattern 13 are isotropically or anisotropically formed. The line electrode 12 is formed by removing the line electrode 12 by selective etching.

Next, as shown in FIG. 3C, after removing the resist pattern 13, a silicon oxide film 14-1 is formed.
It is formed by a method such as a plasma CVD method. The silicon oxide film 14-1 has a refractive index n set to about 1.5 and is formed to have a predetermined thickness (3 μm to 5 μm) that can withstand a high voltage applied between the line electrode 12 and a finger electrode described later.

Next, as shown in FIG. 3D, a silicon nitride film 14-2 having a refractive index of n = 2.0 is formed by the reaction of monosilane (SiH ₄ ) and ammonia (NH ₃ ) by the plasma CVD method. It is formed to a thickness of about 1 μm. next,
As shown in FIG. 3E, a silicon nitride film rich in silicon with a refractive index n = 2.5 due to the reaction of monosilane (SiH ₄ ) and nitrogen (N ₂ ) by plasma CVD method.
14-3 is formed to a thickness of about 0.5 μm. This allows
Silicon oxide film 14-1, silicon nitride film 14-formed so that the refractive index increases from the bottom layer toward the surface layer
2 and the first insulating film 14 made of a silicon nitride film 14-3 rich in silicon are formed.

Next, as shown in FIG. 4, a silicon nitride film is formed.
A finger electrode 15 having a finger hole 18, a second insulating film 16 made of polyimide or the like, and a screen electrode 17 having a screen hole 19 are sequentially formed on the upper part of 14-3 to form the first electrode shown in FIG. A charge generation control element having the same structure as the charge generation control element of the example is completed.

In the embodiment of this manufacturing method,
Although aluminum and titanium are used as the material for the line electrode, the material is not limited to this, and a material having a relatively low resistivity such as copper, molybdenum, or tungsten can also be used. In addition, although a titanium film is used as the aluminum hillock prevention film, titanium nitride, which is a material having a hardness necessary to prevent aluminum hillock, can be used.
In addition to metallic materials such as molybdenum and tungsten, insulating materials such as silicon oxide film can also be used.

The first insulating film 14 is replaced with the silicon oxide film 14
-1, a silicon nitride film 14-2, and a silicon-rich silicon nitride film 14-3 are shown as three layers, but the present invention is not limited to this structure. For example, the silicon oxide film 14-1 may be further composed of a plurality of layers. Can also be formed, phosphorus (P), boron (B)
It is also possible to combine with a relatively soft silicon oxide film containing impurities such as SOG (Spin-On-Glass) film. Further, the silicon-rich silicon nitride film 14-3 may be replaced with an insulating film such as a hard film such as an alumina film or a titanium oxide film.

Further, in an embodiment of this manufacturing method,
As the means for forming the first insulating film, the one using the plasma CVD method has been shown, but the present invention is not limited to this, and the refractive index, that is, the refractive index It is possible to form an insulating layer having different hardness and denseness. In addition, the characteristic diagram shown in FIG. 2A and the same plasma C as shown in FIG.
As can be seen from the characteristic diagram showing the relationship between the refractive index of the insulating film formed by the VD method and the deposition rate and the film stress (compression), the silicon oxide film forming the thick bottom layer having a low refractive index is Since the etching rate is high, the number of steps required for forming and processing the first insulating film can be reduced.

As described above, in the charge generation control element manufactured by this manufacturing method, the first insulating film is formed of a plurality of layers of insulating films having different refractive indexes, and moreover, the corona discharge in the uppermost finger hole is formed. The surface layer exposed to the film is the densest film having the highest refractive index, that is, the hardest, and can be formed relatively thin. As a result, the first by corona discharge
There is no decrease in the insulating film, and a charge generation control element having significantly improved durability can be obtained.

Next, a second embodiment of the charge generation control element and a second embodiment of the manufacturing method thereof will be described with reference to the manufacturing process diagrams shown in FIGS. First, as shown in FIG. 5A, the aluminum film 22-1 having a thickness of about 0.5 μm and the aluminum film 22-1 having a thickness of about 0.3 μm are formed on the quartz (glass) substrate 21 by the same method as in the first embodiment. The titanium film 22-2 and the titanium film 22-2 are successively and sequentially formed in the sputtering apparatus. Next, as shown in FIG. 5B, a resist pattern 23 is formed, and the aluminum film 22-1 and titanium film 22-2 portions not covered with the resist pattern 23 are isotropically or anisotropically formed. The line electrode 22 is formed by removing the line electrode 22 by selective etching.

Next, as shown in FIG. 5C, after removing the resist pattern 23, a silicon oxide film 24-1 having a compressive stress characteristic is formed by a method such as a plasma CVD method. The silicon oxide film 24-1 is formed with a relatively small compressive stress characteristic in consideration of the influence on the line electrode 22. Next, as shown in FIG. 5D, a silicon oxide film 24-2 having a large tensile stress is formed by a method such as atmospheric pressure CVD. The silicon oxide film 24-2 is formed to have a predetermined thickness (3 μm to 5 μm) that can withstand a high voltage applied between the line electrode 22 and a finger electrode described later.

Next, as shown in FIG. 5E, a silicon nitride film 24-3 having a relatively large compressive stress characteristic is formed by a method such as a plasma CVD method. This allows
Silicon oxide film 24-1 having low compressive stress characteristics from the bottom layer to the surface layer, silicon oxide film 24-2 having tensile stress characteristics, and silicon nitride film having high compressive stress characteristics
A first insulating film 24 made of 24-3 is formed.

Next, as shown in FIG. 6, a finger electrode 2 having finger holes 28 on the first insulating film 24.
5, the second insulating film 26 made of polyimide or the like and the screen electrode 27 having the screen hole 29 are sequentially formed to complete the charge generation control element of the second embodiment as shown in FIG.

In this embodiment, since the first insulating film is composed of a plurality of insulating films having different stress characteristics, it is possible to prevent cracks and cracks generated in the first insulating film which is conventionally formed of a thick single layer. It is possible to easily form the first insulating film having a thickness sufficient to obtain a withstand voltage without causing the warp of the quartz substrate, and it is possible to significantly improve the durability.

In the second embodiment, similar to the first embodiment, aluminum and titanium are used as the electrode material of the line electrode, but the present invention is not limited to this.
Materials with relatively low resistivity such as copper, molybdenum, and tungsten can also be used. Further, although the silicon oxide film 24-2 having the tensile stress characteristic which constitutes the first insulating film 24 is shown to be formed by the atmospheric pressure CVD method, the present invention is not limited to this, and the plasma CVD method may be used. By changing the high-frequency frequency, reaction pressure, etc., which are forming conditions, the tensile stress characteristics can be controlled and a silicon oxide film having desired characteristics can be obtained. In addition, organic SOG (Spin-On-Glass)
By thickly applying the film, it is possible to obtain an insulating film having a predetermined thickness and a tensile stress characteristic having a desired withstand voltage.

[0029]

As described above on the basis of the embodiments,
According to the invention of claim 1, it has a predetermined withstand voltage,
In addition, it is possible to realize a charge generation control element having excellent durability without film loss due to corona discharge. According to the second aspect of the present invention, it is possible to provide the first insulating film having the hard, dense and highly durable surface layer. Claim 3
According to the described invention, the first device having the highly durable surface layer is provided.
The insulating film can be easily manufactured. According to the invention described in claim 4, it is possible to realize a charge generation control element including a thick first insulating film having durability and a predetermined withstand voltage without generating cracks or warpage of the substrate. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a charge generation control element according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a refractive index, a film hardness, and a wet etching rate of an insulating film formed by a plasma CVD method, and a relationship between a refractive index and a film stress (compression) and a deposition rate.

FIG. 3 is a diagram showing a manufacturing process for explaining the first embodiment of the method for manufacturing the charge generation control element according to the present invention.

FIG. 4 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 3;

FIG. 5 is a diagram showing a manufacturing process for explaining the second embodiment of the charge generation control element according to the present invention and the second embodiment of the manufacturing method thereof.

FIG. 6 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 5;

FIG. 7 is an explanatory diagram for explaining a problem of the conventional charge generation control element.

[Explanation of symbols]

 1 Insulating Substrate 2 Line Electrode 3 First Insulating Film 3-1 Bottom Layer 3-2 Intermediate Layer 3-3 Surface Layer 4 Finger Electrode 5 Second Insulating Film 6 Screen Electrode 7 Finger Hole 8 Screen Hole 11 Substrate 12 Line Electrode 12-1 Aluminum film 12-2 Titanium film 13 Resist pattern 14 Second insulating film 14-1 Silicon oxide film 14-2 Silicon nitride film 14-3 Silicon-rich silicon nitride film 15 Finger electrode 16 Second insulating film 17 Screen electrode 18 Finger hole 19 Screen hole 21 Substrate 22 Line electrode 22-1 Aluminum film 22-2 Titanium film 23 Resist pattern 24 First insulating film 24-1 Silicon oxide film 24-2 Silicon oxide film 24-3 Silicon nitride film 25 Finger electrode 26 Second insulating film 27 Screen electrode 28 Finger hole 29 Screen hole

Claims (4)

[Claims] 1. A line electrode formed on an insulating substrate,
A first insulating film formed on the surface of the line electrode, a finger electrode formed on the first insulating film and having a hole for charge generation in the center, and a center on the finger electrode surface. In a charge generation control element including a screen electrode having a hole for discharging electric charges at a central portion formed through a second insulating film having a hole for allowing charges to pass therethrough, the first insulating film is It is composed of a plurality of layers, and the refractive index is set to increase sequentially from the bottom layer to the surface layer, and the bottom layer having a low refractive index is set to have a thickness capable of obtaining a predetermined withstand voltage. A characteristic charge generation control element. 2. The surface layer of the first insulating film has a refractive index of
2. The charge generation control element according to claim 1, wherein the silicon of 2.3 or higher is composed of a silicon nitride layer rich in silicon. 3. The method of manufacturing a charge generation control element according to claim 2, wherein the silicon nitride layer forming the surface layer of the first insulating film is formed by a reaction of monosilane and nitrogen by a plasma CVD method. A method of manufacturing a characteristic charge generation control element. 4. A line electrode formed on an insulating substrate,
A first insulating film formed on the surface of the line electrode, a finger electrode formed on the first insulating film and having a hole for charge generation in the center, and a center on the finger electrode surface. In a charge generation control element including a screen electrode having a hole for discharging electric charges at a central portion formed through a second insulating film having a hole for allowing charges to pass therethrough, the first insulating film is A charge generation control element, characterized in that it is formed by alternately laminating insulating layers having a large compressive stress and insulating layers having a large tensile stress.