JPS582032A - Organic thin film formation - Google Patents

Abstract

PURPOSE:To improve the adhesive force of an organic thin film onto a surface of a substrate, by exposing the surface of the substrate to the plasma of non thin film forming gas in a device used for plasma polymerization process before the process. CONSTITUTION:After the Si substrate is washed by ultrasonic wave with trichloroethylene, it is contained in a reactor for plasma polymerization for exhaust to a fixed value of vacuum degree in the reactor. CF4 gas is introduced into this reactor for a fixed internal pressure, then to impress high frequency power on the electrode in the reactor. Thereafter, the reactor is exhausted again to a fixed value of vacuum degree for plasma polymerization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an organic thin film, and more specifically, to a method for forming an organic thin film by plasma polymerization, in which the formed organic thin film has excellent adhesion to a substrate.

It is well known that plasma polymerization is used as one of the methods for forming organic thin films on substrates in the manufacture of electronic devices, optical components, and the like. The plasma polymerization method generally consists of exciting a monomer gas by glow discharge to form an organic thin film, thereby polymerizing the monomer. However, it has been found that when an organic thin film of a polymer is deposited on a substrate in this manner, the adhesion of the organic thin film to the substrate may be poor in the conventional method. One of the possible causes of such a decrease in adhesion is the cleaning process performed on the substrate surface prior to the plasma polymerization process. This is because cleaning with an organic solvent such as acetone or a detergent such as a surfactant is necessary to remove contamination such as oil film, dust, hand grime, etc. adhering to the surface of the substrate. Although cleaning is being carried out,
This is because it is difficult to completely remove adhered contamination with such cleaning. A decrease in adhesion of the substrate also means a decrease in yield.

The present inventors have conducted research to develop a new pretreatment method that can replace and complement the conventional cleaning method, which has the drawbacks mentioned above. We have discovered a new pre-treatment method for chemical treatment that can be carried out in the same equipment. In the method according to the present invention, when plasma polymerization is performed to form an organic thin film on a substrate, prior to the polymerization step, but in the same apparatus, the surface thl of the substrate is treated with a non-thin film-forming material. Consists of exposure to Garth's plasma. ζHere,′
"Non-film-forming", as that term is used herein, refers to the inability to form a thin film on the surface of a substrate, or rather the ability to etch the surface.

When carrying out the present invention, an etching gas commonly used in plasma etching or nupatta etching can be advantageously used as a gas for converting into a product (the pretreatment process according to the present invention is included in the cleaning process). This is because it introduced the idea of Goodsma Etching and #i Nupatta Etching).

Specifically, cr4 is used as a non-thin film forming gas.

CFA 10 02 m 02 1 F2 e
CxWb r ClF5 e C11F1
゜CClF5 −' CCl2F3, CC
l3 a BCl2 e PCti @A
You can give t- such as r. This specific gas depends on the nature of the substrate used and the subsequent f-raz temperature.
They can be appropriately selected and used in consideration of the details of the polymerization process. For example, in the case of CF4 gas, it is thought that the following reaction progresses on a silicon substrate to simultaneously achieve cleaning of the surface of the silicon substrate and slight bifurcation of the surface.

CF4 → CFy, 10F 81 + 4F-+ SiF4 ↑further 1
In the present invention, the type of substrate does not matter at all. So, for example gl e 8102 *At + C
r t Au*Ti, W*GaAs,
The present invention can be applied to various substrates such as various types of glass. The conditions for exposing the surface of the substrate to non-thin film-forming gas plasma are similar to those for the above-mentioned glazma etching or double-volume ivy etching, provided that excessive etching is not possible. It is possible to consider and decide not to do so.

According to the present invention, since contaminants adhering to the substrate can be completely removed prior to the plasma polymerization process, the adhesion of the organic thin film to the substrate surface can be significantly improved. Since it can be used as a contamination removal device for subsequent plasma polymerization, the pretreatment process can be simplified. As a result, the reliability and productivity of the resulting product can be significantly increased.

Next, the present invention will be further explained with reference to the following examples.

Example 1: In this example, cleaning of the St substrate will be explained.

After the prepared St substrate was ultrasonically cleaned with trichlorethylene for 10 minutes, it was placed in a reactor for subsequent Goodsma polymerization. The degree of vacuum inside the reactor is 10''T
evacuate to orr and then charge the reactor with CF
4 gases were introduced to bring the internal pressure to 0.5 Torr. Subsequently, a high frequency of 13.56 MHz was applied to the RF electrode in the reactor at an applied power of 100 W for 20 minutes. After that, the vacuum inside the reactor was reduced to 10-' Torr.
The reactor was evacuated again so that Ic was reached, and then plasma polymerization was carried out according to a conventional method. In this example, styrene was used as the monomer for forming the thin film, and the internal pressure was 0.4 Torr.
and then the RF electrode again until 13.
A high frequency of 56 MHz was applied at an applied power of 30 W for 30 minutes. Plasma 1: After completion of the process, the film thickness is 1μln.
of polymethylene! A film was formed.

For comparison, the above procedure was repeated without exposing the surface of the 81 substrate to the CF4 gas plasma. The adhesion of the I-restyrene thin film thus obtained was compared with that of the thin film produced by the method of the present invention described above. To evaluate the adhesion, a so-called peeling method was used, which is determined from the relationship between the degree of peeling of the thin film and the load used for peeling.

Comparative tests have shown that the adhesion of the thin film produced by the method of the present invention is approximately twice that of the prior art described above.

Example 2: In this example, cleaning of an St substrate having a 1 μmo8302 film with a film thickness will be explained.

The guarded 81 substrate with the 5so2 film was ultrasonically cleaned with trichlorethylene for 10 minutes, and then placed in a reactor for subsequent glazma polymerization. The reactor was evacuated until the temperature at 62 degrees became 10-' Torr, and then a mixed gas of CF4 and 02 (mixture ratio 90:
10) was introduced to bring the internal pressure to 0.4 Torr. Subsequently, a high frequency of 13,56 MHX was applied to the RF [electrode] in the reactor at an applied power of 150 W for 30 minutes. After that, the vacuum inside the reactor was reduced to 10-'Torr.
The inside of the vessel was evacuated again, and then plasma polymerization was carried out according to a conventional method. In this example, methyl methacrylate was used as a seven-layer for forming a thin film, and it was introduced until the pressure inside the chamber reached 0.2 Torr, and then R
A high frequency wave of 13.56 kn (zO) was again applied to the F electrode at an applied power of 20 W for 30 minutes. After the plasma polymerization was completed, a thin film of polymethyl methacrylate with a thickness of 1 μm was formed.

For comparison, the surface of one straw attached to 5i02 was treated with CF4 +
The above procedure was repeated without exposure to the 02 gas mixture. The adhesion test of the obtained thin film of polymethyl methacrylate revealed that the adhesion of the thin film obtained by the method of the present invention was approximately 2.5@ compared to that obtained by this conventional method.

patent applicant Fujitsu Limited patent application agent Patent attorney Tomiki Akira Patent Attorney Kazuyuki Nishi Patent attorney 1) Yukio Patent Attorney Yamaguchi An

Claims (1)

[Claims] 1. When forming an organic thin film on a substrate by the plasma polymerization method, before the plasma polymerization step, the surface of the substrate is heated with a non-thin film forming gas in the same equipment used in that step. An organic thin film formation method characterized by exposure to plasma.