JPS63245891A - Method of forming insulating film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is used in a light emitting element that extracts light through a transparent conductive film, a light receiving element that takes in light, and the like. The present invention relates to a method of forming an insulating film on a transparent substrate on which a transparent conductive film is formed.

(Prior Art) Conventionally, silicon nitride, silicon oxide,
The method for forming a silicon oxynitride film is as follows:
Resistance heating vacuum evaporation method, electron beam heating vacuum evaporation method, sputtering method and plasma CVD (Chemical
There was a vapor deposition method.

(Problems to be solved by the invention) In the vacuum evaporation method, many low-resistance parts occur in the manufactured film due to pinholes and compositional deviations, and between the transparent conductive film and the conductive film formed on the back side of the insulating film. When an electric field is applied to these insulating films, leakage current flowing through the insulating films becomes large, and when the electric field becomes large, dielectric breakdown occurs at the defective portions. In addition, the stamp coverage is poor for protrusions existing on the transparent conductive film, end faces of the patterned transparent conductive film, and minute dust on the transparent conductive film, and the insulating film becomes thin in these areas. This has caused problems such as misalignment, lowering electrical resistance, increasing leakage current, and causing dielectric breakdown.

In addition, although the sputtering method has better sputter coverage than the vacuum evaporation method, it is still not sufficient, the deposition time is long and productivity is low, and the transparent conductive film is exposed to high-energy plasma, so it is not easily damaged by electricity. There are many problems such as increased resistance.

Although most of the above problems are solved by plasma CVD film formation, cranking or peeling of the insulating film occurs when the film is subjected to a heating process after film formation. There is a problem in that this phenomenon becomes more pronounced as the heating temperature in the heating step after film formation is higher and as the film formation area becomes larger. Another problem is that the film is often opaque. This is because the leakage current is abnormally large in this part and the film is not uniform.

The present invention provides a method for forming a transparent and uniform insulating film that has excellent insulating properties (stencil coverage), can withstand a heating process after film formation, and has high productivity.

(Means for Solving the Problems) The present invention involves depositing an insulating film of silicon nitride, silicon oxide, or silicon oxynitride by plasma CVD on a transparent substrate such as a glass plate on which a transparent conductive film is formed. When doing so, the transparent substrate should be
The temperature shall be 0°C.

The plasma CVD method is a method that activates one or more compounds or single gases of the elements constituting the thin film material to be formed at a lower temperature than using heat by exposing them to plasma discharge. This is a vapor deposition method that forms a desired thin film by causing a reaction in the gas phase or on the surface of a substrate.

In general, the plasma CVD method is characterized by low-temperature deposition using plasma, and the substrate temperature is 200 to 300°C. In the present invention, the substrate temperature is raised to 350-550°C. When the substrate temperature is raised, thermal CVD occurs and various side reactions occur, so it is difficult to set the temperature.
C. to 420.degree. C. is preferable; within this range, a uniform film can be obtained with few adverse effects caused by thermal CVD.

As a result, the film deposited in this range can be heated to 550°C after deposition.
No cracks or peeling of the film occurs even through the thermal process.

This was investigated up to a substrate with an area of 1000 m2, and the results were good. Also, if the temperature is outside this range, if it is low, cranking and film peeling will occur during the subsequent thermal process, and if it is high, insulator particles formed at the gas inlet and on the hot plate due to thermal CVD will adhere to the substrate. . Furthermore, when the substrate is returned to room temperature after vapor deposition, the film peels off and cranks occur, and this phenomenon becomes particularly noticeable around the aforementioned deposits. Therefore, the substrate temperature range in which a good film can be obtained is very narrow.

Further, in this method as well, it is preferable that the number of times of continuous vapor deposition is up to 10 times and that the gas inlet is cleaned by sandblasting or the like.

To make the transparent substrate surface 350 to 550℃, the temperature is 0℃ to 5℃.
This can be done by controlling the temperature of a metal plate of about 2 to 5 Qmm to tightly fix a transparent substrate of about mm to 350 to 550°C.

Furthermore, when heating the transparent substrate surface with radiant heat, the temperature of the transparent substrate surface can be measured and controlled with a thermocouple.

Silicon nitride using plasma CVD method.

When forming a thin film of silicon oxide or silicon oxynitride, the gas type is + as a silicon source.
Hydride such as S iH4+ S i2 H6.

S iF t+ S t Cl 4 and other halides, nitrogen sources include NHs, Nz, etc., oxygen sources include N20,02, and diluent gases include N z + A.
r etc. are used. The St/N ratio and the 5i10 ratio are each expressed as a volume ratio of 0 parts of silicon source gas to 100 parts of nitrogen gas.
．． 5 to 80 parts, and 20 to 300 parts of silicon source gas per 100 parts of oxygen source gas. The total pressure of the gas is 0.
1 to 5 t o r r, input power is 0.05 to l O
W/cm2. A frequency of 10 KHz to 50 GHz is used.

Silicon nitride formed by plasma CVD method,
The thickness of the silicon oxide or silicon oxynitride thin film is 0.1 to 3 μm.

As a transparent conductive film, I nz 03 (S n)
+5nOz(Sb), 5nOz(P), 5nOz(Te
).

5nOz(W), 5nOz(CI), 5nOz(F)
Oxide semiconductor films such as 1Cdz 5n04, CdSn0z, CdO, Au, Ag, Cu, Pd,
Pt.

A metal film such as AI, Cr, Rh, etc. is used. The expansion coefficients of these oxide semiconductor films and metal films are twice to several times higher than those of silicon nitride, silicon oxide, and silicon oxynitride formed thereon.

Furthermore, silicon nitride, silicon oxide, and silicon oxynitride generally cause residual stress in the film when deposited by plasma CVD.

Since tensile stress remains, the apparent coefficient of thermal expansion becomes smaller, and from this point of view as well, film peeling and cranking are likely to occur during post-process heat treatment.

In the present invention, when depositing an insulating film of silicon nitride, silicon oxide, or silicon oxynitride by plasma CVD method.

By setting the temperature of the transparent substrate to 350-550°C.

Even if heat treatment is performed as a post-process, the film will not peel off or cracks will occur.

Even if the total area of the transparent conductive film on the transparent substrate is 5a+I or more, according to the present invention, the film will not peel off or cracks will occur even if heat treatment is performed as a post-process.

The transparent conductive film on the transparent substrate can be striped or
Even those formed on the entire surface of a transparent substrate.

Any shape is fine.

Silicon nitride formed by plasma CVD method,
Insulating films made of silicon oxide and silicon oxynitride often exhibit a whitening phenomenon (opacity). As a result of examining this whitening using an electron microscope, it was found that particles of abnormal particle size grew on the transparent conductive film, and a uniform film did not grow. This phenomenon is often seen when the transparent conductive film is thoroughly cleaned, and is considered to be a reaction that occurs on the very surface of the transparent conductive film. In addition, the higher the substrate temperature, the more the whitening phenomenon appears on the face. This is thought to be due to the above-mentioned reaction being promoted, but the cause of particle growth is not clear. Therefore, as a pretreatment for the transparent conductive film, the substrate was subjected to oxygen plasma treatment in a plasma CVD chamber. Conditions are oxygen partial pressure 0.05-1.0t
orr, the injection type varies depending on the device, but the electrode area is 0.05 to IW/cm2, and the substrate temperature is 200 to 550.
A treatment time of several minutes is sufficient. By applying this treatment, no whitening of the membrane was observed at all. Furthermore, even if oxygen gas was replaced with an inert gas such as nitrogen gas or argon, the same effect, although inferior to oxygen plasma, was obtained. Therefore, it is desirable to replace it with nitrogen or an inert gas only when there is a substance on the same substrate that is damaged by oxygen plasma.

In addition, as another treatment method, an insulating material of 1 to 10% is applied on a transparent conductive film.
Having people evaporated was also effective. In such vapor deposition, the insulating material does not cover the transparent conductive film uniformly, but is scattered in an island-like structure.

Eliminating the bleaching phenomenon even in such an island-like structure
It can be seen that this whitening phenomenon is a special phenomenon on the substrate surface. In addition, the insulating film to be thinly applied can be made of any type, such as silicon nitride film by plasma CVD.
When forming a film using D, first, approximately several angstroms of silicon nitride is deposited on the substrate by plasma CVD, and the input power is temporarily turned off.

Even if a silicon nitride film of a predetermined thickness is formed thereon, the whitening phenomenon will not occur. In addition, as an insulator,
Insulating film of silicon oxide and silicon oxynitride by plasma CVD method.

Alternatively, a evaporated film of Al2O3 by about 3 to 10 people may be used.

Example I About 20 In 203 (S n) in borosilicate glass
After forming a film by electron beam heating vacuum evaporation method,
A substrate etched into stripes was used. The substrate was cleaned and placed in a plasma CVD apparatus using a debodown method, the temperature was set to 400° C., and the pressure inside the chamber was reduced to 1.5×10 −6 torr. Afterwards Si
Ha, NZ, and NHs were introduced at a volume ratio of 1:2, the total pressure was Q, 8 torr, and silicon nitride was evaporated for about 5 minutes with an input power of O-18 w/cm2. The obtained silicon nitride film is transparent and has a thickness of approximately 300 mm.
0 people and the leakage current is small (DC voltage 1'OOV
at lo-5, c+A/mm”) 1.OX 107V/
No dielectric breakdown was observed even when an electric field of cm was applied.

Example 2 In the same manner as in Example 1, SiH4 and N20 were introduced at a volume ratio of 25 near 5, the total pressure was Q, 8 torr, and 0.06 W.
Silicon oxide was evaporated for about 1 minute and 30 seconds at a substrate temperature of 410° C. with an input power of /cm 2 to obtain a transparent film with a thickness of about 3000 μm. The leakage current is 10- at a DC voltage of 100
'7 in μA/mm2. No dielectric breakdown was observed even when an electric field of 06 V/cm was applied.

Example 3 SiH4, N2. NH3゜N, O
were introduced at a volume ratio of 9:17:70:4.

Silicon oxynitride was deposited for about 10 minutes at a substrate temperature of 390° C. and an input power of O, I W/cm2.

The thickness of the obtained film was approximately 3000 mm, and the leakage current was 10-5μA/mm2゜1.0xlO'V at a DC voltage of 100cm.
No dielectric breakdown was observed even when an electric field of /cm was applied.

Example 4 A substrate was placed in a chamber in the same manner as in Example 1, the substrate temperature was set at 400°C, and the pressure was reduced to 1.5X10-'torr, then oxygen was introduced and the chamber was heated to Q, 15torr.
After oxygen plasma treatment for about 3 minutes with input power of 0.2 W/cm2 as r, Example 1. 2. Silicon nide, silicon oxide, and silicon oxynitride were deposited in the same manner as in 3. By applying this treatment, the whitening phenomenon that often occurs was completely eliminated, and no change in electrical characteristics was observed.

Further, even when oxygen gas was replaced with nitrogen gas, no whitening phenomenon was observed, but the electrical properties deteriorated by about 5%. However, there are no practical problems.

Example 5 A1□0 was formed on the substrate of Example 1 by electron beam heating vacuum evaporation method.
After depositing Example 3 for about 3 seconds (5 people in terms of monitor), Example 1,
Each film was formed in the same manner as in 2.3. Examples 1 and 2.
Before forming each film in Example 3, plasma was generated for about 2 seconds using the same gas composition and input power as in each example, and then each film was formed in accordance with Example 1, 2, and 3.

By these pretreatments, no whitening phenomenon was observed at all, and a film with excellent electrical properties similar to those obtained by nitrogen plasma treatment was obtained.

(Effects of the Invention) The present invention is suitable for heat treatment. Silicon nitride, silicon oxide, and silicon oxynitride films that do not cause whitening and have good electrical properties can be obtained by plasma CVD. Moreover, this method is excellent in mass production.

Claims (5)

[Claims] 1. An insulation characterized by depositing at least one thin film of silicon nitride, silicon oxide, or silicon oxynitride on a transparent substrate on which a transparent conductive film is formed, by plasma CVD at a temperature of 350 to 550°C. Membrane formation method. 2. 2. The method of forming an insulating film according to claim 1, wherein the transparent substrate is treated in oxygen plasma at 200 to 550° C. and then vapor deposited. 3. 2. The method of forming an insulating film according to claim 1, wherein the transparent substrate is treated in an inert gas plasma at 200 to 550° C. and then vapor deposited. 4. 2. The method of forming an insulating film according to claim 1, wherein the insulating material is deposited on the transparent substrate by 1 to 10 Å, and then the insulating material is deposited. 5. Claim 4, wherein the vapor-deposited insulator with a thickness of 1 to 10 Å is at least one of silicon nitride, silicon oxide, silicon oxynitride, or alumina.
A method for forming an insulating film as described in .