JPH08258326A - Charge generation control element for electrostatic image-forming apparatus - Google Patents

Abstract

PURPOSE: To improve the durability of a first insulating film while preventing the generation of cracks or warping of an insulating substrate, by selectively forming a different insulating film which is harder and finer than the first insulating film on a front face and in the vicinity of the insulating film (first insulating film) located at a hole part of a finger electrode. CONSTITUTION: In order to form the charge generation control element, a metallic line electrode 2 is set on an insulating substrate 1 of glass, alumina or the like, and a first insulating film 3 is formed on a front face of the line electrode 2. A finger electrode 5 with a finger hole 8 at a central part thereof is set at an upper part of the insulating film 3, and a second insulating film 6 with a charge pass hole at a central part thereof and a screen electrode 7 with a charge discharge screen hole 9 at a central part thereof are provided on a front face of the finger electrode 5. A third insulating film 4 which is harder and finer than the insulating film 3 is formed on a front face of the insulating film 3 corresponding to the finger hole 8 of the finger electrode 5 in a manner to be held between the finger electrode 5 and insulating film 3.

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.

[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. 9 is a cross-sectional view showing a part of a configuration example of a conventional charge generator for an electrostatic image forming apparatus. In FIG. 9, reference numeral 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. For the first insulating film 103, a material having a high electrostatic withstand voltage such as 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 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, electric charges are generated on the side wall of the finger hole 107 and on the first insulating film 103 due to a corona discharge phenomenon. Swarms occur. Negative charges having high mobility in this charge group are used for latent image formation. The second insulating film 105 is opposed to the finger electrode 104.
When a positive potential higher than the potential applied to the finger electrodes 104 is applied to the screen electrode 106 formed by interposing, the negative charge generated by the corona discharge is generated.
It is extracted from the screen hole 108 formed in 106. 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]

By the way, when the conventional charge generation control element shown in FIG. 9 is driven, in addition to the electric field of several MV / cm generated inside the first insulating film 103,
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. It is also conceivable to form an insulating film that withstands corona discharge on the entire surface of the first insulating film 103, but the problem of cracks or warpage of the insulating substrate due to film stress cannot be avoided.

The present invention has been made to solve the above problems of the conventional charge generation control element.
It is an object of the present invention to provide a charge generation control element for an electrostatic image forming apparatus, which can improve the durability of the first insulating film while preventing the generation of cracks and the generation of warpage of the insulating substrate. And A fifth aspect of the present invention is to provide a material suitable for forming the third insulating film according to the first to fourth aspects of the invention.

[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 a charge generation control element comprising a screen electrode having a hole for discharging charges in the central portion formed through the insulating film of, the surface of the first insulating film located in the hole of the finger electrode and its surface In the vicinity, the first
The third insulating film, which is harder and more dense than the insulating film, is selectively formed. The invention according to claim 2 is the same as claim 1.
In the charge generation control element for the electrostatic image forming apparatus described,
The third insulating film is formed such that its peripheral portion is sandwiched between the first insulating film and the finger electrode.
According to a third aspect of the invention, in the charge generation control element for an electrostatic image forming apparatus according to the first aspect, the third insulating film is formed in a state of being embedded in the first insulating film. . According to a fourth aspect of the present invention, there is provided the charge generation control element for an electrostatic image forming apparatus according to the first aspect, wherein
Is formed on the surface of the first insulating film located in the hole of the finger electrode and the peripheral wall surface of the hole of the finger electrode.

By thus providing the hard and dense third insulating film, the first insulating film in the hole portion of the finger electrode is formed.
The surface of the first insulating film is not scraped by corona discharge, and the durability of the first insulating film is significantly improved. Further, since the third insulating film is selectively formed on the surface of the first insulating film located in the hole of the finger electrode and in the vicinity thereof,
The generation of cracks in the first insulating film and the warp of the insulating substrate can be completely eliminated, and a charge generation control element that performs stable operation can be realized.

Further, the invention according to claim 5 is defined by claims 1 to 4.
In the charge generation control element for the electrostatic image forming apparatus described,
The third insulating film is made of SiN, SiON, Al ₂ O ₃ , TiO ₂ , Mg
O, BN, P ₂ O ₅ , B ₂ O ₃ , PbO, Ta ₂ O ₅ , ZnO
₂ , ZrO ₂ , Al ₆ Si ₂ O ₁₃ , CaF ₂ , SiC, or DLC. Thereby, the hard and dense third insulating film can be easily formed.

[0012]

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, glass, or alumina, 2 is a line electrode made of metal formed on the insulating substrate 1, and 3 is a first electrode formed on the surfaces of the insulating substrate 1 and the line electrode 2. The insulating films 5 are finger electrodes having a finger hole 8 formed in the center of the first insulating film 3. 4 is formed on the surface of the first insulating film 3 corresponding to the finger holes 8 of the finger electrode 5,
Is a third insulating film selectively formed before the formation of the first insulating film and is made of a harder and denser material than the first insulating film, and its peripheral portion is sandwiched between the first insulating film 3 and the finger electrodes 5. It is arranged in a closed state. Reference numeral 6 is a second insulating film formed in the surface of the finger electrode 5 and having a hole for passing charges in the center, and 7 is a screen hole for discharging charges in the center formed in the surface of the second insulating film 6. 9 is a screen electrode having 9.

In the charge generation control element thus constructed, since the hard and dense third insulating film 4 is formed on the surface of the first insulating film 3 in the finger hole 8,
The first insulating film 3 is reinforced, the film reduction due to the corona discharge generated in the finger holes 8 is prevented, and excellent durability can be provided. Further, since the third insulating film 4 is selectively formed in the portion corresponding to the finger holes 8, the occurrence of cracks in the first insulating film 3 and the insulating substrate 1
It is possible to effectively prevent the occurrence of warpage.

Next, a method of manufacturing the charge generation control element of the first embodiment shown in FIG. 1 will be described with reference to the manufacturing process diagrams shown in FIGS. As shown in FIG. 2A, a titanium film 12a for a line electrode having a thickness of about 0.5 μm is formed on a quartz (glass, alumina) substrate 11. Next, as shown in FIG. 2B, a resist pattern 13 is formed on the titanium film 12a, and a portion of the titanium film 12a not covered with the resist pattern 13 is isotropically or anisotropically. The line electrode 12 is formed by removing it by etching. Next, as shown in FIG. 2C, after removing the resist pattern 13, a silicon oxide film is formed.
14 is formed by a method such as a plasma CVD method, for example, by reacting silane (SiH ₄ ) with nitrous oxide (N ₂ O). The silicon oxide film 14 is formed to have a predetermined thickness (3 μm to 6 μm) capable of withstanding a high voltage applied between the line electrode 12 and a finger electrode described later.

Next, as shown in FIG. 2D, for example, silane (SiH ₄ ) is formed by a plasma CVD method or the like.
The reaction between ammonia and NH ₃ forms a silicon nitride film 15 a having a thickness of about 1 μm. This silicon nitride film is a denser and harder film than the silicon oxide film from the viewpoint of etching rate and film hardness, and also has excellent characteristics in corona discharge resistance. Next, as shown in (A) of FIG.
A resist pattern 16 having an overlap amount of about μm is formed on the silicon nitride film 15a, and a silicon nitride film portion not covered by the resist pattern 16 is formed.
By removing it by isotropic or anisotropic etching, the third insulating film 15 made of a silicon nitride film harder than the first insulating film 14 is selectively formed in the finger hole portion.

Next, as shown in FIG. 3B, the resist pattern 16 is removed, and a titanium film 17a for finger electrodes is formed to a thickness of about 1 μm on the entire surface by a sputtering method or the like. Next, as shown in FIG.
A finger hole pattern is formed by 18, and the titanium film 17a is selectively formed by isotropic or anisotropic etching.
Are removed to form a finger electrode 17 made of a titanium film having finger holes 19. Next, as shown in FIG. 4, after removing the resist 18, a second insulating film 20 having a charge passage hole in the center is formed using a material having excellent heat resistance such as polyimide, and the like. Screen hole 22
By sequentially forming the screen electrode 21 having
A charge generation control element similar to that shown in FIG. 1 is completed.

In the present embodiment, titanium is used as the line electrode material, but the line electrode material is not limited to this, and aluminum, copper, molybdenum,
A material having a relatively low resistivity such as tungsten can also be used. Further, although the silicon oxide film is used as the first insulating film, the first insulating film is not limited to this, and the silicon oxide film or SOG containing impurities such as phosphorus (P) and boron (B) is not limited to this.
(Spin-On-Glass) film etc. can also be used

In this embodiment, plasma CVD is used as the third insulating film having a property different from that of the first insulating film.
Although the one using the silicon nitride film formed by the method is shown, the invention is not limited to this, and alumina films (Al ₂ O ₃ ) and
Magnesium oxide (MgO), titanium oxide (TiO ₂ ), boron nitride (BN), phosphorus pentoxide (P ₂ O ₅ ), boron oxide (B ₂ O ₃ ), lead oxide (PbO), aluminosilicate glass (Al ₆ An insulating film made of Si ₂ O ₁₃ ), diamond-like carbon (DLC), zinc oxide (ZnO ₂ ), zirconium oxide (ZrO ₂ ), calcium fluoride (CaF ₂ ), silicon carbide (SiC), etc. can also be used. .

Next, among these, the forming method in the case of using the alumina film as the third insulating film will be described.
There are three types of methods for forming an alumina film: a CVD method, a PVD (physical reaction) method, and an oxidation method. CVD in it
Taking the method as an example, triethoxyaluminum [Al (OC
₂ H ₅ ) ₃ ] or trimethoxy aluminum [Al
(OCH ₃ ) ₃ ] or the like is formed by thermal decomposition at a reaction temperature of about 350 ° C., or trimethylaluminum [Al (CH ₃ ) ₃ ] and oxygen (O ₂ ) are also formed at a reaction temperature of about 350 ° C. Form. Then, for the purpose of removing the products in the process of decomposition contained in the film, a heat treatment is performed at about 800 ° C. to promote crystallization of the alumina film and form a film having high hardness.

According to the above manufacturing method, the finger holes 19
A third insulating film made of a hard and dense insulating film such as a silicon nitride film and an alumina film can be selectively formed only in a portion exposed to corona discharge. As a result, there is no reduction in the thickness of the first insulating film due to corona discharge, and no cracking of the first insulating film or warpage of the insulating substrate occurs, so durability can be greatly improved.

Next, the structure of the second embodiment will be described with reference to the manufacturing process drawings shown in FIGS. First, as shown in FIG. 5A, a titanium film 32a for a line electrode is sputtered on a quartz (glass) substrate 31 to a thickness of about 0.5 μm by the same method as the manufacturing method of the first embodiment. It is formed by the method. Next, as shown in FIG. 5B, a resist pattern 33 is formed, and a portion of the titanium film 32a not covered with the resist pattern 33 is removed by isotropic or anisotropic etching. The line electrode 32 is formed. Next, as shown in FIG. 5C, after removing the resist pattern 33, a first insulating film 34 made of a silicon oxide film is formed on the entire surface by a method such as plasma CVD and the line electrode 32 and Predetermined thickness (3 μm to 6 μm) that can withstand high voltage applied between finger electrodes
To form.

Next, as shown in FIG. 5D, a resist pattern 35 having an overlap portion which is larger by about 1 μm with respect to a finger hole described later is formed, and the first insulating film not covered with the resist pattern 35. The portion is removed by isotropic or anisotropic etching to a depth of about 1 μm to form a recess 36 in the first insulating film 34. Next, as shown in FIG. 6A, after removing the resist pattern 35, a silicon nitride film 37a for a third insulating film is formed by a method such as a plasma CVD method.
Next, a resist 38 is applied on the entire surface of the silicon nitride film 37a. Next, as shown in FIG. 6B, by anisotropic etching, for example, using a mixed gas of carbon tetrafluoride (CF ₄ ) and oxygen (O ₂ ), the first insulating layer other than the recess 36 is formed. Etching is performed until the film 34 appears. As a result, a third insulating film 37 made of a silicon nitride film is formed in the recess 36.

Next, as shown in FIG. 6C, a titanium film for finger electrodes is formed to a thickness of about 1 μm by a sputtering method or the like, and then a finger hole pattern is formed by a resist 40 to form an isotropic or The titanium film is removed by anisotropic etching to form finger electrodes 39 and finger holes 41. Next, as shown in FIG.
After removing the resist 40, a second insulating film 42 having a charge passage hole in the center is formed of a material having excellent heat resistance such as polyimide, and then a screen electrode 43 having a screen hole 44 in the center is sequentially formed. By doing so, the charge generation control element of the second embodiment is completed.

In this embodiment, titanium is used as the line electrode material, but the material is not limited to this, and a material having a relatively low resistivity such as aluminum, copper, molybdenum, or tungsten can be used. is there. Further, although the silicon oxide film is used as the first insulating film, the present invention is not limited to this, and the silicon oxide film containing impurities such as phosphorus (P) and boron (B) or SOG (Spin-On-Glass) is used.
s) Membranes can be used.

Also in this embodiment, plasma CV is used as the third insulating film having a property different from that of the first insulating film.
Although the one using the silicon nitride film formed by the D method is shown, the invention is not limited to this, and alumina film (Al ₂ O ₃ ), magnesium oxide (MgO), titanium oxide (Ti
O ₂ ), boron nitride (BN), phosphorus pentoxide (P
₂ O ₅ ), boron oxide (B ₂ O ₃ ), lead oxide (PbO),
Aluminosilicate glass (Al ₆ Si ₂ O ₁₃ ), diamond-like carbon (DLC), zinc oxide (ZnO ₂ ),
Zirconium oxide (ZrO ₂ ), calcium fluoride (CaF
₂ ), an insulating film made of silicon carbide (SiC) or the like can also be used.

In this embodiment, the finger holes 41
A third insulating film 37 made of a hard and dense insulating film such as a silicon nitride film or an alumina film is selectively embedded in the first insulating film 34 only in the portion exposed to the corona discharge. Since the first insulating film 34 is arranged, the first insulating film 34 is not thinned by corona discharge, and the first insulating film 34 is not cracked or the insulating substrate 31 is not warped, so that the durability can be significantly improved. . In addition, the third insulating film 37 is the first
Since it is embedded in the insulating film 34 of the
39 can maintain the same shape as the conventional one, and can prevent the occurrence of abnormal discharge due to the protruding portion or the like.

Next, a third embodiment will be described with reference to FIG. Also in this embodiment, the line electrode is formed on the quartz (glass) substrate 51 by the same method as in the first and second embodiments.
After forming 52, a first insulating film 53 made of a silicon oxide film is formed, and subsequently, a finger electrode 54 having a finger hole 58 in the central portion is formed. Then plasma C
A silicon nitride film (or an alumina film) is formed on the entire surface by a method such as the VD method, and 1 μm is formed from the finger holes 58.
After forming a resist pattern having a large size of about m, the silicon nitride film portion not covered with the resist pattern is removed by etching, whereby the finger holes 58 are formed.
A third insulating film 55 made of a hard and dense silicon nitride film is selectively formed on the bottom portion and the peripheral wall portion of the. Then the second
The insulating film 56 is formed of a material having excellent heat resistance such as polyimide, and then a screen electrode having a screen hole 59.
By sequentially forming 57, the charge generation control element having the structure shown in FIG. 8 can be obtained.

Also in this embodiment, since the hard and dense third insulating film such as the silicon nitride film is selectively formed only on the portions of the finger holes exposed to corona discharge, the first by corona discharge is formed. Since there is no reduction in the thickness of the insulating film and no cracking of the first insulating film or warpage of the insulating substrate occurs, durability can be significantly improved.

[0029]

As described above on the basis of the embodiments,
The invention according to claims 1 to 4 selectively forms a third insulating film, which is harder and denser than the first insulating film, on the surface of the first insulating film located in the hole of the finger electrode and in the vicinity thereof. Therefore, the film loss due to corona discharge is eliminated, and the durability of the first insulating film can be significantly improved. In addition, a stable operation can be performed without cracks in the first insulating film or warpage of the insulating substrate. According to the invention of claim 5, the hard and dense third insulating film can be easily formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a charge generation control element for an electrostatic image forming apparatus according to the present invention.

FIG. 2 is a manufacturing process diagram for explaining the manufacturing method of the charge generation control device of the first embodiment shown in FIG.

FIG. 3 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 2;

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 present invention.

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

FIG. 7 is a diagram showing a manufacturing process that follows the manufacturing process shown in FIG. 6;

FIG. 8 is a sectional view showing a third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a problem of the conventional charge generation control element.

[Explanation of symbols]

 1 Insulating Substrate 2 Line Electrode 3 First Insulating Film 4 Third Insulating Film 5 Finger Electrode 6 Second Insulating Film 7 Screen Electrode 8 Finger Hole 9 Screen Hole 11 Substrate 12a Titanium Film 12 Line Electrode 13 Resist Pattern 14 First Insulation film 15a Silicon nitride film 15 Third insulation film 16 Resist pattern 17a Titanium film 17 Finger electrode 18 Resist 19 Finger hole 20 Second insulation film 21 Screen electrode 22 Screen hole 31 Substrate 32a Titanium film 32 Line electrode 33 Resist pattern 34 First insulating film 35 Resist pattern 36 Recess 37a Silicon nitride film 37 Third insulating film 38 Resist 39 Finger electrode 40 Resist 41 Finger hole 42 Second insulating film 43 Screen electrode 44 Screen hole 51 Substrate 52 Line electrode 53 First insulating film 54 Finger electrode 55 Third insulating film 5 6 Second insulating film 57 Screen electrode 58 Finger hole 59 Screen hole

Claims (5)

[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 comprising a screen electrode having a hole for discharging charges in the center formed through a second insulating film having a hole for allowing charges to pass therethrough, An electrostatic image forming apparatus characterized in that a third insulating film, which is harder and denser than the first insulating film, is selectively formed on the surface of the first insulating film located and in the vicinity thereof. Charge generation control element. 2. The electrostatic image according to claim 1, wherein the third insulating film is formed such that a peripheral portion thereof is sandwiched between the first insulating film and the finger electrode. A charge generation control element for a forming device. 3. The charge generation control element for an electrostatic image forming apparatus according to claim 1, wherein the third insulating film is formed by being embedded in the first insulating film. 4. The third insulating film is formed on the surface of the first insulating film located in the hole of the finger electrode and the peripheral wall surface of the hole of the finger electrode. Item 1. A charge generation control element for an electrostatic image forming apparatus according to Item 1. 5. The third insulating film is SiN, SiON, Al
₂ O ₃ , TiO ₂ , MgO, BN, P ₂ O ₅ , B ₂ O ₃ , Pb
O, Ta ₂ O ₅ , ZnO ₂ , ZrO ₂ , Al ₆ Si ₂ O ₁₃ , Ca
F _2, SiC, one of the claims 1 to 4, characterized in that it is composed of a thin film formed by any one of DLC 1
A charge generation control element for an electrostatic image forming apparatus according to the item.