JPS62177189A - Method for local reforming of solid surface by plasma - Google Patents

Abstract

PURPOSE:To permit a necessary treatment only on the specific part of a solid surface by applying a required magnetic field from the atmospheric pressure side to the local part on the solid surface in a low gaseous pressure and forming electron cyclotron resonance plasma near the same. CONSTITUTION:The atm. and the low gaseous pressure part are partitioned by a wall W and microwaves are made incident on the low gaseous pressure side. A disk-shaped permanent magnet PM1 having prescribed intensity is made near to a position P1 from the atm. side, then the value of the magnetic field near the same in the low gaseous pressure part increases gradually. The gaseous molecules in the low gaseous pressure are electrolytically ionized and plasma PL (hatched part) is generated when the value of the magnetic field attains the electron cyclotron resonance (ECR). the carbon film formed to an observation window in the stage of subjecting, characteristic for example, the 1st wall of a nuclear fission synthesizing device to carbonization is removed by making use of such local plasma reaction.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for locally modifying a solid surface (etching, deposition, etc.), and is applicable to a wide range of industries such as semiconductors, plastics, and optical machinery. related to the field.

(Prior Art) In plasma processing, it is generally difficult to perform specific operations locally without applying a mask or the like. For example, when forming a carbon film on the first wall of a nuclear fusion device (the wall directly facing the plasma), it is desirable to avoid forming it on the surface of the plasma observation window (quartz, sapphire, etc.), but I can't avoid it. If the film is formed without a shutter, etc., it can be removed using plasma chemistry (using hydrogen plasma or oxygen plasma), but if you try to remove the carbon film on the window, it will also remove the carbon film on other necessary parts. It disappears and ends.

(Problems to be Solved by the Present Invention) In the present invention, by generating a required processing plasma at a fixed position and controlling it,
The idea is to make it possible to apply different treatments to different locations using solid wall soil.

This will be explained by taking as an example a carbon oxide (a process in which carbon oxide is formed on the first wall surface) of a nuclear fusion device. Since the first wall of the fusion device is exposed to high-energy particles coming out of the high-temperature plasma, material atoms on the wall surface are sputtered.

When operated for a long time, acid particles and metal atoms in the form of sputtered particles enter the plasma and cool it radiatively, causing the plasma to collapse. Therefore, reduction of these impurities is of essential importance.

Recently, as one of the measures to reduce the above-mentioned impurities, hydrocarbons such as C11 are introduced prior to high-temperature plasma generation, and carbonization is performed by performing glow discharge, etc., and the purity in high-temperature plasma is significantly improved. are doing. However, when this method is carried out, the observation window, high-voltage insulator surface, and high-frequency introduction window, where carbon film η is not desirable, are also carbonized, so a complicated and expensive coating is required to prevent this.

In the present invention, for example, after carbonation/ion is performed, a removal plasma (hydrogen or oxidized plasma) is generated in the local vicinity of an observation window, etc., and the carbon film is removed only in this part, and the necessary parts of the pond are: It provides a method to minimize changes.

(Means for Solving the Problem) In the present invention, processing plasma is generated by electron cyclotron resonance (ECR) method. ECR plasma produces an ECR6+' field in the discharge space (a magnetic field flC with a relationship between the microwave frequency f and r - c [lC/2πm).
In 1 ko 5, e and m do not occur unless the electron's charge and quality 1 ko exist. Furthermore, since plasma is generated near the [EC1'1 plane and the generated plasma moves along the lines of magnetic force, the range in which the plasma exists is determined and localized by the ECR plane and the lines of magnetic force. For example, as shown in FIG. 1, it is assumed that the atmosphere and the low gas pressure area are separated by a wall W, and the microwave is incident on the low gas pressure side. When a disk-shaped permanent magnet PM1 with a predetermined strength is brought closer to position P from the atmospheric pressure side,
The value of the magnetic field near this area of low gas pressure gradually increases, and the BCR
When the magnetic field is reached, the gas molecules in the low gas pressure section are electrically charged and plasma PL is generated. The magnetic field lines of PM are roughly shown in the figure (they have a white shape, so they are indicated by diagonal lines in the figure) (·, 'ρ plasma appears.

(Function) By localizing the plasma, the solid surface undergoes local modification through reaction with the plasma. For example, the supply gas when PM is placed at Pl in Figure 1 is [
11, a carbon film will be generated on the surface near P, and if the magnet is then transferred to B2 and 02 is supplied, an oxide layer will be formed on the surface near B2.

(Effect) By using this local plasma reaction, the functionality of the entire solid surface can be enhanced.

Taking the example of the nuclear fusion device δ, the entire first wall is covered with a carbon film, which helps reduce impurities, and removes the local carbon (IQ) necessary for measurements, etc., so that it operates rationally as a whole. It is.

(Example) FIG. 2 is an explanatory diagram of a carbon removal experiment according to the present invention.

A branch pipe BT was attached to the discharge tube DT, which was evacuated using a vacuum pump, and gas was introduced into the tube to maintain a pressure on the order of 10-'Pa. The microwave has a frequency of 2-45 Gllz, and a resonant magnetic field B is applied to the discharge tube DT.

is applied. The sample is a quartz plate CP. First, the light transmission characteristics are measured, and then it is placed at position P3 inside the discharge tube. B5 is applied, and a discharge is performed with a mixed gas of CI+ and H2, and carbon is formed on the surface of the quartz plate CP. Apply a membrane.

The light transmission characteristics are measured again, and then the sample is placed at position P of the branch pipe BT, and a ferrite lid is placed between the samples.
Stones PM2 and PM2' are placed opposite each other and a magnetic field is applied to station F;13. In this case, the magnetic field inside the branch pipe BT is assumed to be 0. Pure H2 is supplied and plasma PL is applied locally to remove the carbon film, after which a smooth light transmission characteristic is obtained. The results of the above three measurements of the light transmission characteristics are shown in FIG. It can be seen that when a carbon film is attached, the absorption of ultraviolet 2JlS increases greatly, but this is removed by hydrogen plasma and almost returns to its original state.

This result proves the correctness of the idea that necessary processing can be performed locally by creating a local processing plasma.

As is already clear from the above-mentioned example, in addition to removing the carbon film formed also on the observation window by carbonizing the first wall of the nuclear fusion device, the present invention also applies to semiconductors. It is similarly effective for cleaning observation windows of manufacturing equipment and for cleaning semiconductor substrates themselves. When etching or forming a film on a semiconductor substrate, it is possible to perform etching or film formation only on the substrate, so there is no possibility of contamination of the substrate by the vacuum chamber wall material or deposition of the film forming material on the vacuum chamber wall. can be avoided as much as possible. Furthermore, different material films can be formed on each of a plurality of substrates installed in the same reaction chamber.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the principle of creating localized plasma using the ECR method, and Figure 2 is a schematic diagram of an embodiment, or the first example of a nuclear fusion device. 'i
When a carbon film is applied to the σII+ window, stains will occur on the window, but this is a schematic diagram of the experimental equipment carried out with the idea of removing this using localized water plasma, Figure 3, and the results of the example Figure 7 shows that when a carbon film is attached to a quartz plate, the absorption of ultraviolet light increases, and when this is removed by local plasma, it is recovered. DT...Discharge tube, py+, P'vI2, PM2'...Magnet,
BT...Branch pipe, PL...Plasma, W
・・・・・・zu:1te.

Claims (1)

[Claims] A method of applying a required magnetic field from the atmospheric pressure side to a local part of the solid surface to be modified, generating electron cyclotron resonance plasma in the vicinity, and modifying only that part.