JPH10247004A - Charge generation control element for electrostatic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the crack or the cut of a finger electrode and to improve the uniformity of an ion current between plural charge generation control elements or to improve yield in the production of the element by selectively forming a dielectric protective film only on the surface of the hole part of the finger electrode of the dielectric film. SOLUTION: The dielectric film 13 is formed on the surfaces of an insulating substrate 11 and a line electrode 12, and the finger electrode 14 having the finger hole 17 at the center part is formed on the film 13. The dielectric protective film 16 selectively formed on the surface of the film 13 in the finger hole 17 of the electrode 14 is constituted of harder and finer material than the film 13. An insulating film 15 having a charge passing hole part at the center part is formed on the surface of the electrode 14. Thus, the film 13 is reinforced by the film 16 in the hole 17, and film wear due to corona discharge generated in the hole 17 is prevented and excellent durability is obtained.

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 Heretofore, a charge generation control element utilizing corona discharge has been used as a method for forming a latent image by electrostatic charge on a dielectric recording medium based on the principle of directly transferring and depositing electric charges on a dielectric recording medium. Is disclosed in Japanese Patent Publication No. 2-62862. The charge generation control device has a structure in which the charge generation control element is manufactured with high definition using a semiconductor fine processing technology and a dielectric protection film is provided for a long life. One of them is disclosed in Japanese Patent Application Laid-Open No. Hei 8-258326 filed by the present applicant.

FIG. 7 is a sectional view showing a charge generation control element disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-258326. In FIG. 7, reference numeral 100 denotes one charge generation control element, and a charge generator for an electrostatic image forming apparatus is constructed by arranging the charge generation control elements 100 one-dimensionally or two-dimensionally. Have been. The charge generation control element 100 includes a substrate 101 made of quartz or glass, a line electrode 102 made of metal, a dielectric film 103, a dielectric protection film 107, a finger electrode 104 made of metal, an insulating film 105, and a screen electrode. 110. The finger electrode 104 has a finger hole 108 formed therein, and the screen electrode 110 has a screen hole 109 formed therein.

The electrodes constituting the charge generation control element 100 are formed by forming a resist pattern on a metal film formed by a sputtering method or a vacuum evaporation method, and then etching a portion not covered by the resist pattern by etching. It is formed by removing. The dielectric film 10
For 3, a material having a high electrostatic withstand voltage, such as silicon oxide or silicon nitride, formed by a method such as a CVD (chemical vapor deposition) method or a sputtering method is used. For the insulating film 105, a resin having high heat resistance such as polyimide is used. The dielectric protection film 107 is made of silicon oxide (Si
A film of aluminum oxide (Al ₂ O ₃ ) or the like having higher hardness and denser properties than O ₂ ) is formed by sputtering or plasma CVD, and selectively etched using a resist pattern in the same manner as the electrodes. It is formed by removing and patterning. At the edge of the finger hole 108 of the finger electrode 104, a step 104a formed by the edge of the dielectric protection film 107 is formed.

Next, the operation of the thus-configured charge generation control device 100 will be described. In FIG.
When an AC voltage is applied between the line electrode 102 and the finger electrode 104 disposed with the dielectric film 103 interposed therebetween, a corona discharge is generated between the side wall of the finger hole 108 and the dielectric protection film 107, and positive and negative corona ions are generated. Occur at high density. A screen electrode 110 formed with an insulating film 105 interposed between the finger electrode 104 and a finger electrode
When a potential higher than the potential applied to 104 is applied, the negative corona ions generated by the corona discharge
It is extracted from a screen hole 109 formed in 110. The negative corona ions extracted from the screen holes 109 are accelerated toward a drum (not shown) which is a dielectric recording medium, and are deposited on the drum to form a charge latent image. Conversely, when a negative potential is applied to the screen electrode 110 with respect to the finger electrode 104, extraction of negative charges from the screen hole 109 is prevented, and no latent image is formed on the drum.

The corona ions generated by the corona discharge generated between the side wall of the finger hole 108 and the dielectric protection film 107 collide with the surface of the dielectric protection film 107 near the corona discharge portion. Due to the high hardness characteristics of 107, the life characteristics of the element and the current stability are improved.

[0007]

By the way, in the structure of the conventional charge generation control device shown in FIG.
The thickness of 107 is 0.5 to 1.0 μm,
Has a thickness of about 1.0 to 7.0 μm, and generally has a thick film structure as a thin film element. Therefore, the distortion of the substrate 101 due to the stress of each film and electrode is relatively large. Therefore, the step portion of the finger electrode 104 due to the dielectric protection film 107 is formed.
Boundary portion 106 of 104a (hereinafter this portion is easily cut
(Referred to as a starting point), cracks occur in the finger electrodes 104. As a result, the electrical resistance of the easy-to-cut portion 106 increases, or in some cases, conduction cannot be obtained, and the state of corona discharge in the finger holes 108 becomes non-uniform between the charge generation control elements 100, or partially corona. There are charge generation control elements 100 from which discharge cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the charge generation control element proposed in the related art, and suppresses cracking or cutting of a finger electrode to reduce the ionic current between a plurality of charge generation control elements. It is an object of the present invention to provide a charge generation control element for an electrostatic image forming apparatus capable of improving the uniformity or the element production yield.

[0009]

Means for Solving the Problems In order to solve the above problems, the invention according to claim 1 comprises a line electrode formed on an insulating substrate, a dielectric film formed on the surface of the line electrode, A finger electrode formed on the top of the dielectric film and having a hole for charge generation in the center and a center formed on the surface of the finger electrode via an insulating film having a hole in the center for allowing charge to pass therethrough. In the charge generation control element comprising a screen electrode having a hole for charge outflow in the portion, only on the surface of the hole of the finger electrode of the dielectric film,
The dielectric protection film is selectively formed.

According to a second aspect of the present invention, there is provided a line electrode formed on an insulating substrate, a dielectric film formed on a surface of the line electrode, and a charge formed in an upper portion of the dielectric film and having a central portion. A finger electrode having a hole for generation, and a screen electrode formed on the surface of the finger electrode via an insulating film having a hole for allowing electric charges to pass through the center, and having a hole for discharging charges in the center. In the charge generation control device, a dielectric protection film is selectively provided on the surface of the hole of the finger electrode of the dielectric film and in the vicinity of the periphery thereof, and the peripheral portion of the dielectric protection film includes the dielectric film and the finger electrode. And the thickness of the peripheral portion is gradually reduced.

By forming the dielectric protection film in this manner, since there is no easy-to-cut portion near the finger hole of the finger electrode, variation in electric resistance of the finger electrode or cutting does not occur. Current generation characteristics can be obtained.

[0012]

Next, an embodiment will be described. FIG. 1 is a sectional view of a first embodiment of a charge generation control element for an electrostatic image forming apparatus according to the present invention. In FIG. 1, reference numeral 10 denotes a single charge generation control element, and a large number of such charge generation control elements are arranged one-dimensionally or two-dimensionally to constitute a charge generator. . 11 is an insulating substrate made of quartz, glass or alumina, 12 is a line electrode made of a metal formed on the insulating substrate 11, 13 is a dielectric film formed on the surface of the insulating substrate 11 and the line electrode 12, and 14 is a dielectric film. It is a finger electrode having a finger hole 17 at the center formed on the dielectric film 13. Reference numeral 16 denotes a dielectric protection film selectively formed on the surface of the dielectric film 13 in the finger hole 17 of the finger electrode 14, and is made of a material that is harder and more dense than the dielectric film 13. Reference numeral 15 denotes an insulating film having a charge passing hole at the center formed on the surface of the finger electrode 14, and 19 denotes a screen electrode having a charge outflow hole 18 at the center formed on the surface of the insulating film 15. It is.

In the charge generation control device thus configured, the dielectric film 13 is reinforced by the dielectric protection film 16 in the finger hole 17, and the film is prevented from being reduced by corona discharge generated in the finger hole 17. Excellent durability can be provided. And since the dielectric protection film 16 is selectively formed only in the finger hole 17,
The finger electrode 14 does not have a portion similar to the easy-to-cut portion (the portion indicated by reference numeral 106 in FIG. 7) as in the above-mentioned conventional proposal. As a result, variations in the electric resistance of the finger electrode 14 or disconnection do not occur, and good ion current generation characteristics can be obtained.

Next, a method of manufacturing the charge generation control element for an electrostatic image forming apparatus according to the first embodiment shown in FIG. 1 will be described with reference to FIGS. 2A to 2G. It will be described based on. First, as shown in FIG. 2A, a titanium film 22a for a line electrode having a thickness of 0.5 μm is formed on a quartz (or glass or alumina) substrate 21. Then, FIG.
As shown in (B), a resist pattern 23 is formed on the titanium film 22a, and portions of the titanium film 22a that are not covered with the resist pattern 23 are removed by etching with a mixed aqueous solution of hydrofluoric acid and nitric acid. I do. Next, as shown in FIG. 2C, after removing the resist pattern 23, a silicon oxide film 24 is formed by a plasma CVD method. The silicon oxide film 24 is formed to a thickness of 5 μm so as to withstand a voltage applied between the line electrode 22 and a finger electrode described later. Next, as shown in FIG. 2D, an aluminum oxide film 25a having a thickness of 1 μm is formed by a sputtering method. The aluminum oxide film 25a has characteristics such as a low etching rate and high film hardness, and is a denser and harder film than the silicon oxide film 24.

Next, as shown in FIG. 2E, a resist pattern 26 having a diameter equal to or smaller than the diameter of a finger hole to be described later is formed on the aluminum oxide film 25a, and the resist pattern 26 is covered. The unexposed portion of the aluminum oxide film 25a is removed by reactive ion etching. As a result, an aluminum oxide film, which is harder than the silicon oxide film 24 as the dielectric film and is to be the dielectric protection film 25, is selectively formed only inside the finger holes. Next, as shown in FIG. 2F, the resist pattern 26 is removed, and a titanium film 27a for a finger electrode is formed in a thickness of 1 to 5 μm on the entire surface by a sputtering method. Next, as shown in FIG.
To form a finger hole pattern, and selectively remove the titanium film 27a by etching with a mixed aqueous solution of hydrofluoric acid and nitric acid to form a finger electrode 27 made of a titanium film having finger holes 29. Thereafter, after removing the resist 28, an insulating film having a charge passing hole in the center is formed using polyimide, and subsequently, a screen electrode having a screen hole is sequentially formed, and the charge generation control shown in FIG. Complete the device.

In the above-described manufacturing method, the case where titanium was used as the line electrode material was described. However, the line electrode material is not limited to this, and materials having relatively low resistivity such as aluminum, copper, molybdenum, and tungsten are used. Can also be used. In addition, although a film using a silicon oxide film as the dielectric film has been described, the present invention is not limited to this, and a silicon oxide film containing impurities such as phosphorus (P), boron (B), or SO
A G (Spin-On-Glass) film can also be used. Also,
As a dielectric protective film having a property different from that of a dielectric film, a dielectric protective film using an aluminum oxide film formed by a sputtering method has been described. However, the present invention is not limited to this, and a silicon nitride film (Si ₃ N
₄ ), magnesium oxide (MgO), titanium oxide (TiO ₂ ), boron oxide (B ₂ O ₃ ), lead oxide (Pb
O), aluminosilicate glass (Al ₆ Si ₂ O ₁₃ ), diamond-like carbon (DLC), zinc oxide (ZnO
₂ ), zirconium oxide (ZrO ₂ ), calcium fluoride (CaF ₂ ), silicon carbide (SiC) or the like can be used as the dielectric protection film.

According to the above manufacturing method, the finger hole
A dielectric protection film 25 made of a hard and dense film such as an aluminum oxide film or a silicon nitride film can be selectively formed on a portion of the film 29 exposed to corona discharge. This eliminates the loss of the dielectric film (silicon oxide film 24) due to corona discharge, and greatly improves the durability of the element. In addition, the finger electrode 27 does not have an easy-to-cut portion, so that a charge generation control element having stable ion current generation characteristics and capable of obtaining an extremely uniform and high-quality electrostatic image can be obtained.

In the first embodiment shown in FIG. 1, the side wall of the finger hole 17 of the finger electrode 14 and the outer peripheral wall of the dielectric protection film 16 are slightly separated from each other, as shown in FIG. As described above, the diameter of the dielectric protection film 16 and the diameter of the finger hole 17 may be the same. In this case, when the dielectric protection film 16 is manufactured based on the manufacturing process shown in FIG. Are substantially thicker as shown for edge coverage.

Next, a second embodiment will be described with reference to FIG. In FIG. 4, reference numeral 30 denotes a single charge generation control element, 31 denotes an insulating substrate made of quartz, glass or alumina, 32 denotes a line electrode made of a metal formed on the insulating substrate, and 33 denotes the insulating substrate 31 A dielectric film 34 formed on the surface of the line electrode 32 is a finger electrode having a finger hole 37 at the center formed on the dielectric film 33. 36 is the finger electrode on the surface of the dielectric film 33 corresponding to the finger hole 37 of the finger electrode.
Dielectric protective film selectively formed before forming 34
It is made of a material that is harder and denser than 33, and its peripheral part is formed so that its thickness gradually decreases, and the dielectric film
It is arranged in a state of being sandwiched between 33 and finger electrodes 34. Reference numeral 35 denotes an insulating film having a charge passage hole at the center formed on the surface of the finger electrode 34, and 39 denotes an insulating film.
This is a screen electrode having a screen hole 38 for discharging charges in the center formed on the surface of 35.

In the charge generation control device thus constructed, the hard and dense dielectric protection film 36 is formed on the surface of the dielectric film 33 in the finger hole 37, so that the dielectric film 33
Are prevented from being reduced by corona discharge generated in the finger holes 37, and excellent durability can be provided. Further, the substrate 31 caused by the stress of each film layer
The occurrence of cracks on the finger electrode 34 caused by the distortion of the finger electrode 34 can be suppressed because there is no step on the finger electrode 34 equivalent to the easy-to-cut portion in the above-mentioned conventional proposal. As a result, variations in the electric resistance of the finger electrode 34, disconnection, and the like do not occur, and good ion current generation characteristics can be obtained.

Next, a method of manufacturing the charge generation control device according to the second embodiment shown in FIG. 4 will be described with reference to FIGS.
Description will be made based on the manufacturing process diagram of (D). First, as shown in FIG. 5A, a quartz substrate 41, a line electrode 42, a silicon oxide film 44, and an aluminum oxide film 45a are formed by the same method as the manufacturing method of the first embodiment shown in FIG. Is formed, and a resist 50a is formed on the aluminum oxide film 45a.
Only the regions (a) and (b) are selectively irradiated with exposure light via a photomask (not shown). Since the resist 50a used here is a positive type, after development, the resist pattern 50 has a shape as shown in FIG. 5B. If the amount of exposure to the resist 50a is set to five times the proper value, the exposure light is excessively scattered inside the resist 50a, and a region that is blocked by a photomask (not shown) is also slightly exposed. As a result, the resist pattern 50
Has a gently shaped end. Using the resist pattern 50 thus formed as a mask, the aluminum oxide film 45a is selectively removed by a reactive ion etching method or an ion milling method, and is made of an aluminum oxide film as shown in FIG. The dielectric protection film 51 is formed. The thickness of the dielectric protection film 51 in the peripheral portion is gradually reduced. This is because, as described above, the resist pattern 50 formed so as to have a gentle edge is used as an etching mask.

According to "Semiconductor Research Vol. 14" (edited by the Semiconductor Research Promotion Association, published by the Industrial Research Council on December 5, 1997, page 210), the angle on the substrate 60 as shown in FIG. When a resist pattern 61 having an end inclined at θ is formed and the substrate 60 is selectively ion-etched, FIG.
As shown in the figure, the resist pattern
61 is subjected to side etching, and as a result, the substrate 60 is also etched into a pattern having a shape with an inclined end.
This is because the dependence of the S value of the resist material on the angle θ is
It is derived from having characteristics as shown in FIG.
Here, the S value is a value defined as the number of atoms etched by one incident ion, and S (θ)
Cos θ is proportional to the probability that the inclined surface having the angle θ is side-etched in the horizontal direction. From FIG. 6C, when θ is around 60 degrees, the value of S (60 °) · cos (60 °) is S (0 °).
°), the amount of side etching of the mask pattern is large, the dimension of the substrate pattern is reduced,
In addition, the gentleness of the end is most noticeable.

After the step shown in FIG. 5C, a titanium film is formed on the entire surface by a sputtering method as shown in FIG. 5D, and the first embodiment shown in FIG. A finger electrode 47 having a finger hole 49 is formed on the aluminum oxide film 51 in the same manner as in the method of manufacturing the charge generation control element according to the embodiment. Further thereon, an insulating film 52 having a charge passage hole in the center is formed using a material having excellent heat resistance such as polyimide, and subsequently, a screen electrode 54 having a screen hole 53 is sequentially formed. A charge generation control device having the same configuration as that shown in FIG. 4 is completed.

In the above-mentioned manufacturing method, the case where titanium was used as the line electrode was described. However, the material of the line electrode is not limited to this, and aluminum, copper, molybdenum,
A material having a relatively low resistivity such as tungsten can also be used. In addition, although a film using a silicon oxide film as the dielectric film is shown, the present invention is not limited to this, and phosphorus (P), boron (B)
Silicon oxide film containing impurities such as SOG (Sp
In-On-Glass) membranes can also be used. Further, as the dielectric protection film having a property different from that of the dielectric film, a film using an aluminum oxide film formed by a sputtering method has been described, but is not limited thereto, and a silicon nitride film (Si ₃ N ₄ ) may be used.
, 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 ), a dielectric protective film made of silicon carbide (SiC) or the like can also be used.

A dielectric protective film having a gentle peripheral portion.
As another processing method 51, there is over-etching by a wet etching method. For example, when a silicon nitride film is used for the dielectric protection film 51, the substrate with the resist pattern 50 formed (FIG. 5B) is immersed in a phosphoric acid aqueous solution heated to 80 ° C. 51 can be selectively etched. In this case, if the etching time is twice as long as a normal appropriate etching time, a dielectric protection film having a gentle peripheral portion can be formed as in the case of the ion etching. This is because the etching progresses isotropically, so that the side etching is excessively performed by the long-time etching, and the amount of the side etching progresses more in the portion near the surface.

According to the method of manufacturing the charge generation control element according to the second embodiment, the portion exposed to the corona discharge in the finger hole is selectively made of a hard dense film such as a silicon nitride film or an alumina film. It is possible to form a dielectric protection film made of a simple film. As a result, the thickness of the dielectric film is not reduced by corona discharge, and the durability of the element is greatly improved. In addition, since the thickness of the peripheral portion of the dielectric protection film is gradually reduced, no steep step occurs in the finger electrode formed thereon. Therefore, a charge generation control element which does not generate an easily cut portion unlike the conventional proposals, has stable ion current generation characteristics, and can obtain an extremely uniform and high-quality electrostatic image can be obtained.

[0027]

As described above with reference to the embodiments, according to the present invention, since there is no easy-to-cut portion in the finger electrode, there is no variation in the electric resistance of the finger electrode, no cutting, etc. It is possible to realize a charge generation control element having ion current generation characteristics and capable of suppressing its time variation to be small.

[Brief description of the drawings]

FIG. 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.

FIG. 2 is a manufacturing process diagram for explaining a method of manufacturing the charge generation control element for an electrostatic image forming apparatus according to the first embodiment shown in FIG.

FIG. 3 is a cross-sectional view showing a modification of the first embodiment shown in FIG.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a manufacturing process diagram for explaining a method of manufacturing the charge generation control element for an electrostatic image forming apparatus according to the second embodiment shown in FIG.

FIG. 6 is an explanatory diagram for explaining a mode in which a pattern having a shape whose end is inclined is etched.

FIG. 7 is a cross-sectional view illustrating a charge generation control element for an electrostatic image forming apparatus proposed in the past.

[Explanation of symbols]

 10, 30 Charge generation control element 11, 31 Insulating substrate 12, 32 Line electrode 13, 33 Dielectric film 14, 34 Finger electrode 15, 35 Insulating film 16, 36 Dielectric protective film 17, 37 Finger hole 18, 38 Screen hole 19, 39 Screen electrode 21, 41 Quartz substrate 22a, 27a Titanium film 22, 42 Line electrode 23, 26, 28, 50 Resist pattern 24, 44 Silicon oxide film 25a, 45a Aluminum oxide film 25, 51 Dielectric protective film 27, 47 Finger electrode 29,49 Finger hole 50a Resist 52 Insulation film 53 Screen electrode 54 Screen hole 60 Substrate 61 Resist pattern

Claims (3)

[Claims] A line electrode formed on an insulating substrate;
A dielectric film formed on the surface of the line electrode, a finger electrode formed on the dielectric film and having a hole for charge generation in the center, and allowing the charge to pass through the finger electrode surface to the center In a charge generation control element comprising a screen electrode having a hole for charge outflow in the center formed on an insulating film having a hole, only on the surface of the hole of the finger electrode of the dielectric film, A charge generation control element for an electrostatic image forming apparatus, wherein a dielectric protection film is selectively formed. 2. A line electrode formed on an insulating substrate,
A dielectric film formed on the surface of the line electrode, a finger electrode formed on the dielectric film and having a hole for charge generation in the center, and allowing the charge to pass through the finger electrode surface to the center In a charge generation control element comprising a screen electrode having a hole for discharging charges in the center formed through an insulating film having a hole, a surface of the hole of the finger electrode of the dielectric film and a vicinity thereof. A dielectric protection film is selectively provided, a peripheral portion of the dielectric protection film is sandwiched between the dielectric film and the finger electrode, and a thickness of the peripheral portion is gradually reduced. Charge generation control element for electrostatic image forming apparatus. 3. The charge generation control element for an electrostatic image forming apparatus according to claim 1, wherein the dielectric protection film is harder and more dense than the dielectric film.