JPS6187872A - Anode electrode in parallel plane sheet type plasma cvd apparatus - Google Patents

Abstract

PURPOSE:To give arbitrary concn. distribution to hole for blowing out raw material gas, by providing a cylinder for supplying gas into anode electrode, communicating small hole of the cylinder and that of anode electrode, and sliding a piston in the cylinder. CONSTITUTION:A porous sheet 4 is provided to an outer wall 1 of anode electrode, and a cylinder 7 is embedded at the center part. Pores of the sheet 4 care communicated to pores of side wall of the cylinder 7 by partitions 6. Carrier gas is introduced from a pipe 9 at upper part of the cylinder 7. A piston 5 attached with a pipe 8 is slid in the cylinder 7, and gaseous raw material is introduced from a pipe 8, blown out from inside holes of the sheet 4, and carrier gas is blown out from outside holes thereof. Blowing out radius of both gases are varied by sliding the piston 5. Thus, arbitrary gas concn. distribution can be given to gas blowing hole corresponding to variation in film forming condition, and uniform concn. distribution can be realized.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to uniform film formation using a parallel plate plasma CVD apparatus, and is particularly suitable for achieving uniform film formation in response to changes in other film formation conditions. This invention relates to a gas outlet with variable concentration distribution.

[Background of the invention]

As described in Japanese Patent Application Laid-open No. 56-94748, the conventional apparatus has a partition plate fixed within the anode electrode, and is adapted to only meet certain specific film-forming conditions. but,
No consideration was given to adapting the same device to other film forming conditions without disassembling or performing additional work.

[Purpose of the invention]

An object of the present invention is to provide a gas outlet that provides an arbitrary concentration distribution to the raw material gas outlet in response to changes in film-forming conditions and achieves a uniform film thickness distribution even when the film-forming conditions change. be.

[Summary of the invention]

When raw material gas is blown out at a uniform concentration, the concentration is almost uniform in the area between the two parallel plate electrodes, but the concentration of radicals generated due to variations in plasma electron density and differences in flow velocity may vary. A distribution occurs. Therefore, if the concentration of the source gas is distributed in advance so as to offset variations in electron density and flow rate, the concentration of generated radicals can be made uniform, and a uniform film thickness distribution can be obtained. At this time, since the distribution that should be given to the concentration of the raw material gas differs depending on the film forming conditions, the gas outlet is partitioned by several concentric plates, and the positions of the high-concentration raw material gas and inert carrier gas are simplified. I made it possible to change it with a mechanism.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a sectional view showing the structure inside a vacuum chamber of a parallel plate type plasma CVD apparatus. High-frequency power is applied to the anode electrode 1 and the cathode electrode 2 to generate a plasma region between them. The raw material gas blown out from the anode electrode is activated as it passes through the plasma region and deposits a film on the substrate 3. do.

FIG. 2 shows a gas outlet and an anode electrode for imparting an arbitrary concentration distribution to the raw material gas. A porous plate 4 is attached to the outer wall 1 of the electrode, and a cylinder 7 is installed in the center. The holes in the perforated plate communicate with holes provided in the side wall of the cylinder 7 by means of several conical partitions 6. Again, cylinder 7 l! Pipe 9 is attached to the top of Im.
Inert carrier gas is introduced through this pipe. On the other hand, the piston 5 to which the pipe 8 is attached slides inside the cylinder 7. A highly concentrated raw material gas is introduced through the pipe 8.

Therefore, the raw material gas comes out from the hole in the cylinder side wall below the piston 5, passes through the area narrowed by the conical partition 6, and is blown into the chamber from the hole in the perforated plate 2. On the other hand, the carrier gas It exits from a hole in the cylinder side wall located higher up and blows out into the chamber as well. Among the holes in the perforated plate, high-concentration raw material gas is blown out from holes located inside a certain radius, and carrier gas is blown out from holes outside this radius, and this radius can be changed by sliding the piston. be able to.

Generally, the central part has a high gas flow rate and the residence time of the plasma region is short, so it is activated and it is necessary to make the central part a high concentration.
It is also possible to introduce a carrier gas into the pipe 9 and a highly concentrated raw material gas into the pipe 9 to make the peripheral area of the porous plate highly concentrated.

〔Effect of the invention〕

According to the present invention, in accordance with changes in plasma electron density and flow velocity due to changes in film forming conditions (for example, changes in pressure, changes in RF power, changes in raw material gas, etc.), these can be offset. The concentration distribution of the source gas at the gas outlet can be changed. Further, in this case, there is no need to disassemble the device or perform additional work, and adjustment can be made only by sliding the piston, which has the effect of easily realizing uniform film formation. Furthermore, since the sliding surfaces between the piston and the cylinder do not move during film formation, there is no particular technical problem with the sealing.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure inside a chamber of a parallel plate plasma CVD apparatus according to the present invention, and FIG. 2 is a cross-sectional view of a gas outlet and anode electrode according to an embodiment of the present invention. 1... Anode electrode, 2... Cathode electrode,
311. Substrate, 4... Perforated plate, 5...
・Piston, 6... Conical upper partition, 7...
・Cylinder, 8...Gas introduction pipe, 9・
...1 gas introduction pipe

Claims (1)

[Claims] 1. A parallel plate type having a vacuum evacuation means, a gas supply means, an anode electrode having a porous gas outlet, a cathode electrode opposite to the anode electrode with a substrate attached thereto, and a chamber containing these electrodes and maintaining a predetermined low-pressure atmosphere. In a plasma CVD apparatus, a cylinder having a gas supply port in an anode electrode having a porous gas outlet and a porous outlet on the side surface, and a flow connecting the small hole of the small hole hyanodic electrode of the cylinder. A parallel plate type plasma CV characterized by having a plurality of members forming passages and a piston slidable within the cylinder and equipped with a gas supply port in the center.
Anode electrode of D device.