JPH0315198A - High frequency power induction device for generating reactive plasma - Google Patents

Abstract

PURPOSE:To reduce deterioration due to the deposition of reactive particles onto an air tight window as well as to improve working efficiency with cleaning reduced in number by interchangeably providing plural numbers of shielding plates for wall surfaces faced with each other between the air tight window provided for a high frequency power induction passage and the side of an output end. CONSTITUTION:One circular shield plate 71 and the other circular shield plate 72 are interchangeably disposed fixedly from the inner side of an outer conductive body 61 and the outside of a coaxial tube inner conductive body 4 respectively in a space between the air tight window 2 of a plasma furnace and the side of an output end 3. This therefore prevents reactive particles from coming to the air tight window 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-frequency power introduction device for plasma generation in a reactive plasma device widely used, for example, in the semiconductor industry and the surface treatment industry. [Prior Art] Conventionally, in this type of high-frequency power introduction device, a coaxial pipe or a waveguide is used as the introduction line, and an airtight window made of a dielectric material is provided in the line (pipe). ．． [Problems to be Solved by the Invention] However, there is no shielding between the output side of the above-mentioned airtight window, for example, the power radiation antenna in the case of a coaxial pipe, or the output aperture in the case of a waveguide. Due to exposure to the plasma atmosphere, reactive particles of the plasma constantly collide with the airtight window at high speed, and reactive substances gradually accumulate on the surface of the window, reducing the transmission efficiency of high-frequency power. There is a risk that the high-frequency power may eventually be short-circuited on the airtight window surface. Therefore,
It is necessary to frequently disassemble the airtight window and clean the deposited material on the surface after each use, exposing the inside of the plasma container to the atmosphere each time, which significantly reduces work efficiency. An object of the present invention is to reduce the number of times of cleaning and improve work efficiency by minimizing contamination caused by vapor deposition of reactive substances on the airtight windows. [Means for Solving the Problems] In order to achieve the above objectives, the present invention has the following precepts. That is, the opposing wall surfaces in the introduction line between the airtight window and the output tip of the high frequency power introduction line, for example, the inner surface of the outer conductor and the outer surface of the inner conductor in the case of a coaxial tube line, and the outer surface of the inner conductor in the case of a waveguide line. It is characterized in that a plurality of shielding plates made of a conductor or dielectric for preventing contamination of the airtight window are alternately provided on the inner wall surfaces facing each other. [Function] As mentioned above, a plurality of shielding plates for preventing contamination of the airtight window are alternately installed on the opposing walls of the introduction line between the airtight window of the high frequency power introduction line and the output tip. The path of reactive particles traveling straight from the plasma generation region on the output end side of the introduction line toward the airtight window is blocked by the shielding plate, thereby reducing contamination of the airtight window by the reactive particles as much as possible. becomes possible. [Example] FIG. 1 is an example in which the present invention is implemented in a high-frequency power introduction section for reactive plasma generation using a coaxial tube circuit. In the diagram, 1 is the plasma reactor container? , 2 is an airtight window made of a dielectric material, 3 is an output hole, 4 is a coaxial tube conductor, and 5 is a power radiation antenna. High frequency output power is guided into the plasma reactor through the airtight window 2. An annular shielding plate 7 is inserted from the inside of the outer conductor 61 between the airtight window 2 and the output end 3 side. In addition, a large number of disc-shaped shielding plates 7■ are alternately implanted from the outside of the coaxial pipe inner conductor 4. The adjacent shielding plate 7.・7■ is the second
As shown in the figure, they overlap each other when viewed from the tube axis direction, so that the airtight window 2 is not visible from the output hole 3. Therefore, even if reactive particles traveling in a straight line pass through a small gap, they will be blocked by the next shielding plate.
Most of it does not reach the airtight windows. Note that the above-mentioned temporary shields 7 and 7 may be made of a metal conductor or a dielectric material. Furthermore, if their thickness is thin relative to the frequency used, they will have little effect on high frequency transmission characteristics. At the commonly used industrial frequency of 13.56MHz, the frequency is 0.
A 5-open metal plate could be used without any problems. ? However, when used at high frequencies such as microwaves, the thickness of the shielding plate may affect the transmission characteristics. In such a case, the spacing and dimensions of the shielding plates may be changed to provide filter characteristics. The airtight window 2 is attached with flanges 8 and 8, and is kept airtight by a packing 9 in a circumferential groove provided in the inner and outer conductors. When used in the microwave band, a waveguide circuit is often used. Figures 3 and 4 show an example of such a case, in which a large number of flat shielding plates 7I and 7■ are alternately implanted from opposite surfaces of a waveguide 6t attached to the plasma reactor wall 1. be. As shown in Fig. 4, each of the shielding plates 7I and 7t extends close to the opposing surfaces, and any reactive particles that leak through the small gaps are blocked by the next shielding plate and do not reach the airtight window. , it becomes only a very small amount.
Therefore, contamination of the airtight window is greatly reduced, and work efficiency is greatly improved. Is there a possibility that the thickness of the shielding plate may have an adverse effect? In this case, for example, the spacing between one group of shielding plates 7l and the thickness of the other shielding plate 7■ placed between them are adjusted so as to exhibit filter characteristics. [Effects of the Invention] As explained above, the present invention achieves the above-mentioned effect by alternately providing a plurality of shielding plates on the opposing wall surface in the introduction line between the airtight window provided in the high frequency power introduction line and the output tip. Since the path of reactive particles traveling straight toward the airtight window is blocked, it is possible to minimize the contamination of the airtight window by reactive particles, and the number of cleaning times for the airtight window can be significantly reduced. Can be done. In fact, for example, in the semiconductor manufacturing industry, where work is often continuous for 24 hours, it is extremely important to improve the work efficiency of reactive plasma furnaces, and it is desirable to minimize the number of cleanings mentioned above. However, according to the present invention, the number of times of cleaning was reduced to several tenths of that of the conventional method, and work efficiency and productivity were significantly improved.

[Brief explanation of drawings]

? Figure 1 is a longitudinal sectional view of an embodiment in which the present invention is applied to a power introduction part of a plasma device using a coaxial tube circuit, Figure 2 is a side view thereof, and Figure 3 is a power introduction part using a waveguide circuit. Fig. 4 is a longitudinal cross-sectional view of an embodiment to which the present invention is applied. 1 is the vessel wall of the plasma reactor, 2 is the airtight window, 3 is the output hole,
4 is a coaxial pipe inner conductor, 5 is a power radiation antenna, 6 is a coaxial pipe outer conductor, 6■ is a waveguide, 7, 72 is a shielding plate, 8,
・8. 9 is the mounting tsuba, and 9 is the airtight backing.

Claims (1)

[Claims] (1) A plurality of shielding plates made of a conductor or dielectric to prevent contamination of the airtight window are alternately provided on the opposing walls in the introduction line between the airtight window of the high frequency power introduction line and the output tip. A high-frequency power introduction device for reactive plasma generation characterized by the following.