JP2000133649A - Formation of insulating film on element circuit substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of an insulating film, which can readily form the insulating film having the excellent insulating characteristics on a substrate with less process number. SOLUTION: The forming method of an insulating film 2 contains the process which discharges the sol containing the material of an insulating film on a substrate 1 by an ink jetting device 3, and the process for baking this sol- attached substrate. Before the discharging process, the process which applies a surface-quality improving film on the substrate 1 is included. In this case, by providing a surface-quality improving film between the substrate 1 and an insulating film 2, a contact angle θ between the end part of the insulating film and the substrate can be made small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an insulating layer on a circuit board of an electric element, a glass substrate of quartz glass, soda glass, lead glass, or the like, or a substrate of silicon, ceramic, etc. The present invention relates to a method for manufacturing an insulating layer used for an emission element circuit board.

[0002]

2. Description of the Related Art Conventionally, an insulating film is formed on a substrate by a screen printing method using a glass paste, a CVD method (chemical vapor deposition method), an LPD method (liquid phase deposition film forming method), or a sol-gel method. This was done by various coatings.

[0003] In the printing method, a commercially available glass paste (for example, manufactured by Noritake Co., Ltd.) is applied on a substrate by a method such as a screen printing method, and is then heated to 500 ° C.
A film is formed by firing at 600 ° C. The formed insulating film has a thickness of about 20 to 50 μm and a relative dielectric constant of 10 to 3
It is about 0.

In the CVD method, a substrate is placed under reduced pressure using a vacuum apparatus, and a silicon-based gas is vapor-deposited or silicon is oxidized by a carrier gas such as argon, helium, oxygen or the like and a reaction gas to a thickness of about 1 μm. An SiO ₂ film is formed.

In the LPD method, SiO ₂ is dissolved at low temperature in an aqueous solution of hydrofluoric acid to form a supersaturated solution, and the substrate is immersed in the solution and heated to about 30 to 40 ° C. to deposit SiO ₂ on the substrate ( Temperature method) or aluminum
The chemical equilibrium is shifted by adding water and boric acid, and SiO ₂ is deposited on the substrate to form a film.

In the sol-gel method, commercially available sol-gel liquids (eg, Atron manufactured by Nippon Soda Co., Ltd., Tosgard manufactured by Toshiba Silicone Co., Ltd.), and a preparation prepared by dissolving a silane compound such as tetraethoxysilane in a suitable solvent such as ethanol. Is applied on a substrate by using a technique such as dipping, spraying or spin coating, and is baked at about 300 ° C. to form a film. The film thickness is 1 to 3 μm, and the relative dielectric constant is about 3 to 15.

On the other hand, as an application of a circuit board having such an insulating film formed thereon, there is an image forming apparatus using a surface conduction electron-emitting device. Hereinafter, the surface conduction electron-emitting device will be briefly described.

[0008] As electron-emitting devices, there are roughly two types of thermionic and cold-cathode electron-emitting devices. The cold cathode electron emitting device includes a field emission type (hereinafter, referred to as “FE type”), a metal / insulating layer / metal type (hereinafter, referred to as “MIM type”), a surface conduction type electron emitting device, and the like. Surface-conduction electron-emitting devices consist of a small-area thin film formed on a substrate,
This utilizes the phenomenon that electron emission occurs when a current flows in parallel to the film surface. This surface conduction electron-emitting device is disclosed in I. Elinson et al. Using a SnO ₂ thin film, Au thin film (M. Hartw
ell and C.I. G. FIG. Fonstad. , IEEE
Trans. ED conf. , 519 (197)
5)), those using a carbon thin film (Hisashi Araki et al., Vacuum, Vol. 26, No. 1, Item 22 (1983)) and the like are already known.

A typical device configuration of these surface conduction electron-emitting devices is described in the above-mentioned Hartwell (M. Hart).
FIG. 5 schematically shows the device configuration of the present invention. In the figure, reference numeral 51 denotes a substrate. Numeral 54 denotes a conductive thin film, which is made of a metal oxide thin film or the like formed by sputtering in an H-shaped pattern, and the electron emitting portion 55 is formed by an energization process called energization forming. The distance L between the device electrodes 52 and 53 in the figure is 0.5 to 1 mm, and W is 0.1
mm.

In these surface conduction electron-emitting devices, before the electron emission, the conductive thin film 54 is generally subjected to an energization process called energization forming in advance to form an electron emission portion 55. That is, energization forming means applying a DC voltage or a very slowly increasing voltage, for example, about 1 V / min, to both ends of the conductive thin film 54 and energizing the conductive thin film 54 to locally destroy, deform or alter the conductive thin film. Emitter 55 in a state of high resistance
Is to form In the electron emitting portion 55, a crack is generated in a part of the conductive thin film 54, and electrons are emitted from the vicinity of the crack. In the surface conduction type electron-emitting device subjected to the energization forming process, a voltage is applied to the conductive thin film 54 and a current is caused to flow through the device to cause the electron-emitting portion 55 to emit electrons.

The above-described surface conduction electron-emitting device has a simple structure and is easy to manufacture, and thus has an advantage that a large number of devices can be arranged and formed over a large area. Therefore, taking advantage of this feature, application studies of this element to an electron beam source, a display device, and the like have been made.

An image forming apparatus using a surface conduction electron-emitting device is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-299136.

[0013]

The above-described conventional methods for forming an insulating film have the following problems, respectively. That is, in the printing method, since a glass paste is used, only a thick film having a thickness of several tens of μm or more is formed. In addition, since there are many components such as PbO, the relative dielectric constant is increased and the insulating characteristics are deteriorated. there were.

The CVD method has the drawbacks that it is difficult to increase the area of the substrate because a vacuum apparatus is used and a high vacuum is required, the cost of the apparatus is high, and the throughput is small.

The LPD method has the disadvantage that the film forming speed is very slow and the throughput decreases in proportion to the film thickness. There is also a disadvantage that an insulating layer can be formed only on SiO ₂ .

The sol-gel method requires a process of forming a solid film by a technique such as dip, spin, spray and the like, and then forming a pattern by a technique such as photolithography and etching. Was.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an insulating film which is suitable for easily forming an insulating film having good insulating properties at a required place on various substrates with a small number of steps. .

[0018]

The above object can be achieved by the present invention described below. That is, a first aspect of the present invention is a method for forming an insulating film on a substrate by a sol-gel method, wherein (1) a step of discharging an insulating film material-containing sol onto the substrate by inkjet, and (2) A step of firing the attached substrate to form an insulating film over the substrate.

The second invention includes a step (0) of applying a surface modifier on a substrate before the discharging step (1),
Next, in the method (1), the sol is discharged onto the surface-modified substrate.

According to a third aspect of the present invention, there is provided the insulating film forming method according to the first or second aspect, wherein in the firing step (2), first, the preliminary firing is performed, and then the main firing is performed at a temperature higher than the temperature of the temporary firing. It is.

In a fourth aspect, the sol has a viscosity of 1.0 to 1.0.
An insulating film forming method according to the first or second aspect of the present invention, which is adjusted to a range of 10.0 cps.

A fifth invention is the method for forming an insulating film according to the second invention, wherein the surface modifier is a silane coupling agent.

A sixth invention is the method of forming an insulating film according to any one of the first to fifth inventions, wherein a contact angle between an end of the insulating film and the substrate is controlled to be less than 90 degrees.

According to a seventh aspect of the present invention, there is provided the insulating film according to any one of the first to sixth aspects, wherein the insulating film is formed as an interlayer insulating film for a surface conduction electron-emitting device or an image forming apparatus using the device. This is a film formation method.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments. FIG. 1 is a schematic diagram of a cross section (a) and an upper surface (b) of an insulating film formed on a substrate by the method of the present invention. In FIG. 1, reference numeral 1 denotes a substrate, 2 denotes an insulating layer, 3 denotes an ink discharge portion of an ink jet device, and θ denotes a contact angle between the end of the insulating layer and the substrate.

The substrate 1 used in the present invention is appropriately selected from, for example, glass substrates such as silicate glass, soda-lime glass, lead glass and borosilicate glass, ceramic substrates such as alumina, metals, and silicon.

The insulating layer 2 according to the present invention is formed by loading a sol containing an insulating layer material as an ink into an ink jet apparatus, discharging the sol from an ink discharging section 3 and attaching the ink to a substrate, and then performing a firing step. The insulating film material-containing sol used in the present invention may be a preparation prepared by dissolving a silane compound such as tetraethoxysilane in an appropriate solvent such as ethanol, or a commercially available sol-gel solution (Atron manufactured by Nippon Soda Co., Ltd., Toshiba Silicone Co., Ltd.). And HAS-10) manufactured by Colcoat Co., Ltd. may be used. Further, a composition containing a chelate salt, an organic alkali metal salt, an organic alkaline earth metal salt, or the like of aluminum, which may be prepared so that it becomes only an inorganic oxide when fired (eg, manufactured by Toray Dow Corning Co., Ltd.) AY-49-208). That is, a liquid composition that forms an insulating film by firing is preferably used.

The above-mentioned sol containing the insulating film material may have a certain degree of viscosity, but is preferably about 1.0 to 10 cps from the suitability of the ink jet apparatus.

As the ink jet device used in the present invention, a bubble jet type using an electrothermal converter or a piezo jet type using a piezoelectric element can be used as an energy generating element. Can be set arbitrarily.

The contact angle θ between the end of the insulating layer and the substrate
Is desirably controlled to be smaller than 90 degrees. This is to improve the step coverage when forming the wiring on the insulating layer. In order to control the contact angle θ to be small, the substrate must be U-shaped before the sol containing the insulating layer material is discharged.
It is necessary to clean the surface by V ozone treatment or the like.
Further, as a method for ensuring the controllability, a thin silane coupling agent is preferably applied in advance to a portion where the sol containing the insulating layer material is discharged.

The sol is not required to be ejected only once by ink jet, but may be overprinted. This method is effective for forming a thick film.

The sol containing the insulating film material discharged onto the substrate as described above is then fired. In this step, temporary firing is performed as necessary, and then main firing is performed. The pre-baking temperature is usually lower than the boiling point of the active ingredient (for example, silicone compound) of the insulating film material-containing sol, and is preferably about 60 to 200 ° C., more preferably 60 to 100 ° C., because there is no volatilization of the active ingredient. . In addition, the main baking is preferably performed at a temperature at which the alkoxy group of the silicone compound is eliminated and the dehydration reaction sufficiently proceeds.
Perform at or above ° C.

When an interlayer insulating layer of an image forming apparatus using a surface conduction electron-emitting device is formed by the method of the present invention, a dense insulating film can be formed in a small number of steps with less material and cost. Is advantageous.

[0034]

EXAMPLES Hereinafter, the present invention will be further described with reference to examples and the like, but the present invention is not limited to these examples. Embodiment 1 FIG. 2 is a schematic sectional view of a matrix wiring board forming step according to an embodiment of the present invention.

First, as shown in FIG. 2 (a), 230 μm
Every 1 μm thick and 100 μm wide, silver paste wiring 22
Was formed.

Another wiring 24 is formed on the wiring 22 so as to be perpendicular to the wiring 22. Before that, the position (interlayer insulating portion) of the wiring 22 where the wiring 24 should intersect is insulated using an ink jet device. The sol containing the film material was discharged. As this sol, a sol-gel liquid Atron (manufactured by Nippon Soda Co., Ltd.) whose viscosity was adjusted to 3.5 (cps) was used. Then 14
Preliminary baking was performed at 0 ° C. for 15 minutes, and further baking was performed at 450 ° C. for 1 hour to form the interlayer insulating film 23 of FIG. 2B.
This film was a dense film having a thickness of 2 μm. The dielectric constant was 4.3, and a film very close to SiO ₂ was obtained.

Subsequently, as shown in FIG. 2C, a silver paste wiring 24 having a thickness of 1 μm and a width of 100 μm was formed every 230 μm as an upper wiring.

In this embodiment, the matrix wiring circuit board insulated by the interlayer insulating film 23 can be manufactured by the above-mentioned few simple steps. No short circuit between these wirings and no disconnection of the wirings were observed.

Example 2 In the same manner as in Example 1, as shown in FIG.
The silver paste wiring 22 was wired with a thickness of 1 μm and a width of 100 μm every μm.

Next, at a position (interlayer insulating portion) at which the wiring is to intersect with the wiring 24 which is to be disposed later so as to be orthogonal to the upper part of the wiring 22,
Using an inkjet device, the viscosity is 5.0 (cps)
The ethyl silicate 40 (manufactured by Colcoat Co., Ltd.) is discharged, and then calcined at 140 ° C. for 15 minutes and further calcined at 450 ° C. for 1 hour to form the interlayer insulating film 23 shown in FIG. did. The film thickness at this time is 3 μm
It was a dense film. The dielectric constant is 4.5 and SiO
_A film very close to ₂ was obtained.

Finally, as shown in FIG. 2 (c), a silver paste wiring 24 having a thickness of 1 μm and a width of 100 μm is formed every 230 μm as an upper wiring, and a matrix wiring substrate insulated by an interlayer insulating film 23 is formed as described above. It was able to be created with few simple steps as described above. Short-circuiting between these wirings, disconnection of the wirings, and the like were not observed as in Example 1.

Embodiment 3 FIG. 3 is a schematic sectional view of a step of forming a matrix wiring board according to an embodiment of the present invention. First, as shown in FIG. 3A, a soda-lime glass 31 of A4 size and 2 mm thick is used.
Then, a silver paste wiring 32 having a thickness of 1 μm and a width of 100 μm was formed every 230 μm. Next, a silane coupling agent KBM502 (manufactured by Shin-Etsu Chemical Co., Ltd.) having methacryloxy as a functional group was diluted to 10% with alcohol, and this was thinly coated on the entire surface of the substrate with a spinner to form a ground surface modified film 33. .

Next, an expected crossing position (interlayer insulating portion) with the wiring 35 disposed orthogonally to the upper part of the wiring 32
In addition, using an inkjet device, the viscosity is 3.5 (cp)
The sol-gel liquid Atron (manufactured by Nippon Soda Co., Ltd.) adjusted in step s) is discharged, and then calcined at 140 ° C. for 15 minutes, and further calcined at 450 ° C. for 1 hour, and the interlayer insulating film shown in FIG. 34 were formed. The contact angle of the end of the interlayer insulating film 34 with the substrate (silane coupling agent) was controlled in the range of 60 to 70 degrees. The thickness of the insulating film 34 was 2 μm and a dense film. The dielectric constant was 4.3, and a film very close to SiO ₂ was obtained.

Finally, as shown in FIG. 3C, a silver paste wiring 35 having a thickness of 1 μm and a width of 100 μm is formed every 230 μm as an upper wiring, and the matrix wiring substrate insulated by the interlayer insulating film 34 is formed as described above. It was able to be created with few simple steps as described above. No short circuit between these wirings and no disconnection of the wirings were observed.

Comparative Example 1 FIG. 4 is a schematic sectional view of a matrix wiring substrate forming step according to a comparative example of the present invention. First, as shown in FIG. 4A, a silver paste wiring 42 having a thickness of 1 μm and a width of 100 μm was formed every 230 μm on an A4 size soda lime glass 41 having a thickness of 2 mm.

Next, as shown in FIG. 4B, a positive resist OMR-800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was spin-coated and prebaked at 80 ° C. for 30 minutes. Next, after performing mask exposure and development to remove excess resist, post-baking is performed at 140 ° C. for 30 minutes, and FIG.
A resist 43 was formed as shown in FIG.

Next, the entire substrate was immersed in a sol-gel liquid Atron (manufactured by Nippon Soda Co., Ltd.) whose viscosity was adjusted to 5.5 (cps) for 10 minutes, and pulled up at a pulling rate of 600 mm / min (FIG. 4 (d)). )). Then, after sufficiently waiting until the dripping of the liquid disappeared, it was calcined at 140 ° C. for 15 minutes. Thereafter, the resist 43 is stripped with a resist stripper,
The main baking was performed at 50 ° C. for 1 hour to form an interlayer insulating film 44 as shown in FIG. The contact angle of the end of the interlayer insulating film 44 with the substrate was as large as 90 degrees to 100 degrees. The film thickness was 2 μm and the dielectric constant was 4.5.

Finally, as shown in FIG. 4F, a silver paste wiring 45 is formed as a top wiring at a thickness of 1 μm and a width of 100 μm every 230 μm to form a matrix wiring substrate insulated by an interlayer insulating film 44. did.

As described above, the conventionally used method requires twice or more steps as compared with the method of the present invention. Also,
In the substrate of this comparative example, there was no short circuit between the wirings, but several disconnections of the upper wiring as indicated by 46 in FIG. 4F were observed.

[0050]

As is apparent from the above description, according to the method of the present invention, a sol-gel agent such as a metal alkoxide is discharged onto a substrate by using an ink jet and baked, thereby obtaining a dense and good insulating material. There is an effect that a film can be easily formed with a small number of steps, and a formation area and a formation pattern can be easily changed.

Further, according to the present invention, the surface of the substrate is modified with a silane coupling agent or the like before the insulating material is formed by discharging, so that the contact angle of the end portion of the insulating film with the substrate is reduced to about 60 degrees. This has the effect of improving the step coverage when forming the wiring on the upper part thereof and preventing the wiring from being disconnected.

[Brief description of the drawings]

FIG. 1 is a schematic view of an insulating layer formed on a substrate by a method of the present invention.

FIG. 2 is a schematic sectional view illustrating a method for manufacturing an insulating layer according to the present invention.

FIG. 3 is a schematic sectional view illustrating a method for manufacturing an insulating layer according to the present invention.

FIG. 4 is a schematic cross-sectional view illustrating a method for manufacturing an insulating layer of a comparative example.

FIG. 5 is a plan view of a surface conduction electron-emitting device.

[Explanation of symbols]

1, 21, 31, 41, 51: substrate, 2, 23, 34,
44: insulating film, 3: inkjet device, 22, 24,
32, 35, 42, 45: silver paste wiring layer, 33: surface modified film, 43: resist, 46: disconnection, 52, 5
3: device electrode, 54: conductive thin film, 55: electron emitting portion.

Claims (7)

[Claims] 1. A method for forming an insulating film on a substrate by a sol-gel method, comprising: (1) a step of discharging an insulating film material-containing sol onto the substrate by ink jet; and (2) a step of: Baking to form an insulating film over the substrate. 2. The method according to claim 1, further comprising: a step (0) of applying a surface modifying agent on the substrate before the discharging step (1). 2. The method of forming an insulating film according to claim 1, wherein the liquid is discharged. 3. The insulating film forming method according to claim 1, wherein in the firing step (2), first, preliminary firing is performed, and then main firing is performed at a temperature higher than the temperature of the temporary firing. 4. The viscosity of the sol is 1.0 to 10.0 cp.
3. The method for forming an insulating film according to claim 1, wherein the value is adjusted to a range of s. 5. The method according to claim 2, wherein the surface modifier is a silane coupling agent. 6. The insulating film forming method according to claim 1, wherein a contact angle between an end of said insulating film and said substrate is controlled to be less than 90 degrees. 7. The method for forming an insulating film according to claim 1, wherein said insulating film is formed as an interlayer insulating film for a surface conduction electron-emitting device or an image forming apparatus using said device.