JP2009260199A - Plasma cvd device, and plasma cvd method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma CVD device capable of manufacturing a semiconductor thin film having excellent film quality by reducing generation of SiH<SB>2</SB>radicals degrading power generation performance in silane plasma, and preventing drop of the temperature of a substrate during film formation. <P>SOLUTION: This plasma CVD device is configured to include: a chamber 1; an exhaust device keeping the inside of the chamber 1 in a depressurized condition; a plurality of discharge electrodes 15a and 15b generating plasma in a material gas by being supplied with power; a power source applying A.C. or high-frequency voltages different in polarity to the respective discharge electrodes 15a and 15b adjacent to each other; material gas supply tubes 17 introducing the material gas between the discharge electrodes 15a and 15b adjacent to each other; and barrier ribs arranged from the exits of the material gas supply tubes 17 to a location which is located on the extension line in the material gas flow direction and at which a film formation object substrate 10 is arranged. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a plasma film forming apparatus for forming a thin film, and particularly for forming a thin film suitable as an apparatus using a plasma enhanced chemical vapor deposition method used for manufacturing a semiconductor thin film such as an amorphous silicon thin film solar cell and a display thin film transistor. The present invention relates to a plasma film forming apparatus.

Several apparatuses for producing an amorphous silicon thin film using a plasma-enhanced chemical vapor deposition (CVD) method (hereinafter referred to as plasma CVD method) have been known. Conventionally, a discharge electrode is disposed opposite to a stage on which a film formation substrate is placed, and discharge is performed by supplying a source gas from a number of holes provided on the surface of the discharge electrode. In this technique, the distance between the deposition target substrate on the stage and the plasma is reduced, and the deposition target substrate is damaged by electric discharge, thereby degrading the characteristics of the amorphous silicon thin film. Further, since the distance between the plasma and the deposition target substrate is short, SiH ₂ radicals unnecessary for the deposition of high-quality amorphous silicon are deposited on the substrate.

Therefore, a source gas is supplied between a plurality of electrodes at a predetermined position from the deposition substrate, plasma is generated at a predetermined position from the deposition substrate, and only radicals necessary for film formation of high-quality amorphous silicon are obtained. Has been disclosed (Patent Document 1).
JP 2001-338885 A

  However, in the technique of Patent Document 1, since the source gas reaches the deposition target substrate directly, the temperature decrease near the deposition target substrate is promoted, and the defect density of the amorphous silicon film is increased. It becomes difficult to make silicon.

Therefore, the present invention provides a manufacturing apparatus capable of manufacturing a semiconductor thin film having excellent film quality by making it difficult for SiH ₂ radicals, which reduce power generation performance in silane plasma, to be deposited on a substrate and further controlling the substrate temperature. The purpose is to provide.

In order to solve the above problems, the plasma CVD apparatus of the present invention has the following configuration. That is,
A chamber;
An exhaust device for keeping the inside of the chamber under reduced pressure;
A plurality of discharge electrodes for generating plasma in the source gas by being supplied with electric power;
A power supply for applying alternating current or high frequency voltage of different polarity to each of the adjacent discharge electrodes;
A source gas supply pipe for introducing a source gas between the adjacent discharge electrodes;
And a barrier provided between an outlet of the source gas supply pipe and an extension line in the source gas flow direction and a position where the deposition target substrate is placed.

Further, the plasma CVD method of the present invention is performed by the following procedure. That is,
Hold the inside of the chamber under reduced pressure,
Introducing source gas from the source gas supply pipe between adjacent discharge electrodes,
Applying alternating current or high frequency voltage with different polarity to each of the adjacent discharge electrodes to generate plasma in the source gas,
A barrier is provided between the outlet of the source gas supply pipe and an extension line in the source gas flow direction and a position where the deposition target substrate is placed,
This is a plasma CVD method in which the source gas is made to collide with the barrier and then reach the deposition target substrate to form a thin film on the deposition target substrate.

According to the present invention, a semiconductor thin film having excellent film quality is manufactured by reducing the deposition of SiH ₂ radicals on the substrate, which lowers the power generation performance in silane plasma, and further preventing the substrate temperature from dropping during film formation. A manufacturing apparatus that can be provided can be provided.

  The plasma CVD apparatus of the present invention will be described with reference to the drawings.

The plasma CVD apparatus of the present invention is an apparatus having a configuration as shown in FIG. 1, FIG. 3, or FIG. 1, 3 and 4 are schematic cross-sectional views of a plasma CVD apparatus according to the present invention as seen from the side. This apparatus includes a chamber 1 for generating plasma therein. A plurality of discharge electrodes 15 are arranged inside the chamber 1. There are two types of discharge electrodes 15, and two types of discharge electrodes are alternately arranged. A source gas supply pipe is provided between the discharge electrodes 15 as shown in FIGS. 1 and 3 or in the discharge electrode 15 itself as shown in FIG. The distance between the discharge electrode 15 and the substrate stage 11 on which the deposition target substrate 10 is placed is a predetermined distance apart. For this reason, a horizontal discharge occurs between a plurality of electrodes and plasma is generated. However, this plasma is less likely to directly hit the deposition target substrate 10, and damage to the deposition target substrate 10 due to plasma is reduced. Can do. In addition, since the deposition target substrate 10 and the plasma are separated from each other, it is possible to prevent deposition of SiH ₂ radicals, which reduce power generation performance generated in the plasma, on the deposition target substrate 10.

  The plasma CVD apparatus according to the present invention has a barrier for receiving the source gas as shown in FIG. 3 on the extension line of the source gas flow direction from the source gas supply pipe 17 and a discharge instead of the barrier as shown in FIGS. It is characterized by the presence of the electrode 15. With such a configuration, since the source gas does not directly hit the deposition target substrate 10, the deposition target substrate 10 is less likely to be cooled by the source gas supplied into the chamber 1, thereby reducing power generation performance. The occurrence of defects can be suppressed.

  Hereinafter, specific examples of the plasma CVD apparatus according to the present invention will be described in detail with reference to the drawings.

[First Plasma CVD Apparatus of the Present Invention]
FIG. 1 is a schematic sectional view of the first plasma CVD apparatus of the present invention as seen from the side. The plasma CVD apparatus includes a chamber 1, a source gas supply pipe 17 that supplies a source gas into the chamber 1, a vacuum exhaust device 13, a discharge electrode 15 and a substrate stage 11 that are accommodated in the chamber 1, The high-frequency power supply 14 supplies power to the discharge electrode. A film formation substrate 10 is set on the substrate stage 11 and a thin film is formed on the surface of the film formation substrate. The outlet of the source gas supply pipe 17 is located between the discharge electrodes 15, and the source gas supply pipe 17 is inclined obliquely when viewed from the front. By tilting the source gas supply pipe 17 not directly below, the source gas supplied into the chamber hits the discharge electrode 15 first, not the deposition target substrate 10. That is, the discharge electrode 15 serves as a barrier. In this way, since the supplied source gas does not directly reach the deposition target substrate 10, the vicinity of the deposition target substrate 10 is not cooled by the source gas, and defects that reduce power generation performance can be formed on the substrate. It becomes difficult. It is sufficient that the source gas hits the discharge electrode 15 once, but it is also preferable to repeat that the source gas once bounced off the discharge electrode 15 hits the opposing discharge electrode 15 again. This is because when the source gas strikes the discharge electrode 15 two or more times, the source gas is diffused between the electrodes, making it difficult to reach the deposition target substrate 10. FIG. 2 is a schematic view of the discharge electrode of the plasma CVD apparatus of FIG. 1 as viewed from above. The source gas supply pipe 17 exists in a slit shape between the discharge electrodes 15. Of course, the source gas supply pipe 17 may not have a slit shape, but may have a configuration in which a plurality of holes are provided with a minimum interval.

[Second Plasma CVD Apparatus of the Present Invention]
FIG. 3 is a schematic cross-sectional view of one of the second plasma CVD apparatuses of the present invention as seen from the side. The difference from the first plasma CVD apparatus described above is that a barrier 18 exists on the extended line in the direction of flow of the source gas from the source gas supply pipe 17 and above the deposition target substrate 10. The source gas flowing in from the source gas supply pipe 17 first hits the barrier 18 without hitting the deposition target substrate. Plasma is generated above the barrier 18 and between the discharge electrodes 15. Since plasma does not directly hit the deposition target substrate 10, SiH ₂ radicals that reduce power generation performance are less likely to be deposited on the deposition target substrate 10. Further, since the source gas flowing into the chamber 1 first hits the barrier 18, the source gas does not directly hit the deposition target substrate 10, so the probability that the deposition target substrate 10 is cooled by the source gas is reduced.

[Third plasma CVD apparatus of the present invention]
FIG. 4 is a schematic cross-sectional view of one of the third plasma CVD apparatuses of the present invention as seen from the side. The difference from the first plasma CVD apparatus described above is that the source gas supply pipe 17 is in the discharge electrode 15 as shown in FIG. 5, and the outlet of the source gas supply pipe exists on the surface of the discharge electrode. The source gas that has passed through the source gas supply pipe 17 is supplied to the plasma generation space 2 between the discharge electrodes 15. There are opposing discharge electrodes on an extension line in the direction of flow of the raw material gas from the raw material gas supply pipe 17. Thereby, the plasma can be confined in the vicinity of the discharge electrode 15. In addition, since the supplied source gas first hits the other discharge electrode 15 and does not directly hit the deposition target substrate 10, the probability that the deposition target substrate 10 is cooled by the supplied source gas is reduced.

  In FIG. 5, the raw material gas is supplied from both of the two discharge electrodes 15 facing each other, but the supply of the raw material gas may be one of the discharge electrodes facing each other. Preferably one is good. When gases are supplied from both electrodes, the supplied gases collide with each other, the pressure in the vicinity of the electrodes rises, and good quality amorphous silicon may not be obtained. Further, if there is a discharge electrode facing the extension line in the direction of flow of the raw material gas, the raw material gas may be discharged obliquely with respect to the surface of the discharge electrode. However, as shown in FIG. It is preferred to release in the vertical direction. This is because the source gas is discharged in the vertical direction, so that the source gas more reliably hits the opposing discharge electrodes.

[Preferred Discharge Electrode Shape 1 of Plasma CVD Apparatus of the Present Invention]
FIG. 6 is a schematic view of the discharge electrode support plate 16 and the discharge electrode 15 of the preferred plasma CVD apparatus according to the present invention as seen from below. Since the discharge electrodes 15a and 15b are installed in a double vortex on the electrode support plate 16, radicals generated from the uniformly generated plasma are uniformly transported onto the deposition target substrate 10. Thus, a uniform semiconductor thin film can be obtained.
Since plasma is generated on the electrode surface both in the vertical direction (vertical direction in FIG. 6) and in the horizontal direction (horizontal direction in FIG. 6), the plasma can be more uniformly distributed in the plane.

[Preferred Discharge Electrode Shape 2 of Plasma CVD Apparatus of the Present Invention]
FIG. 7 is a schematic view of the discharge electrode support plate 16 and the discharge electrode 15 of the preferred plasma CVD apparatus according to the present invention as seen from below. Since the comb-shaped discharge electrodes 15a and 15b are alternately arranged on the electrode support plate 16, radicals generated from the uniformly generated plasma are uniformly transported onto the deposition target substrate 10. A uniform semiconductor thin film can be obtained.
Since plasma is generated on the electrode surface both in the vertical direction (vertical direction in FIG. 7) and in the horizontal direction (horizontal direction in FIG. 7), the plasma can be distributed more uniformly in the plane.

According to the present invention described in detail above, it is possible to reduce the deposition of SiH ₂ radicals, which reduce power generation performance in the silane discharge plasma, on the deposition target substrate, and it is difficult for the source gas to cool the substrate. Since defects are less likely to be generated, an excellent semiconductor thin film can be manufactured. As a result, an amorphous silicon thin film useful for a solar cell, a thin film transistor of a liquid crystal display device, or the like can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The general | schematic sectional drawing which looked at the 1st plasma CVD apparatus of this invention from the front. Schematic which looked at the discharge electrode of the 1st plasma CVD apparatus of this invention from right below. The general | schematic sectional drawing which looked at the 2nd plasma CVD apparatus of this invention from the front. The general | schematic sectional drawing which looked at the 3rd plasma CVD apparatus of this invention from the front. Schematic which looked at the discharge electrode of the 3rd plasma CVD apparatus of this invention from the cross section. The schematic which looked at the discharge electrode of the double spiral shape concerning this invention from the lower side. Schematic which looked at the comb-shaped discharge electrode concerning this invention from the lower side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Chamber, 2 ... Plasma production space, 3 ... Radical transport space, 4 ... Film growth surface, 10 ... Substrate to be formed, 11 ... Substrate stage, 12 ... Substrate heater, 13 ... Vacuum exhaust apparatus, 14 ... High frequency power supply, DESCRIPTION OF SYMBOLS 15 ... Discharge electrode, 16 ... Discharge electrode support plate, 17 ... Raw material gas supply pipe, 18 ... Barrier

Claims (8)

A chamber;
An exhaust device for keeping the inside of the chamber under reduced pressure;
A plurality of discharge electrodes for generating plasma in the source gas by being supplied with electric power;
A power supply for applying alternating current or high frequency voltage of different polarity to each of the adjacent discharge electrodes;
A source gas supply pipe for introducing a source gas between the adjacent discharge electrodes;
And a barrier provided between the outlet of the source gas supply pipe and an extended line in the source gas flow direction and a position where the deposition target substrate is placed. The source gas supply pipe is directed so that an outlet of the source gas supply pipe is between the adjacent discharge electrodes, and one discharge electrode of the adjacent discharge electrode is on an extension line in the source gas flow direction. ,
The plasma CVD apparatus according to claim 1, wherein the one discharge electrode itself also serves as a barrier instead of the barrier.   The outlet of the source gas supply pipe is located between the adjacent discharge electrodes, and the source gas supply pipe is directed so that none of the adjacent discharge electrodes is on an extension line in the source gas flow direction. 2. The plasma CVD apparatus according to 1. The source gas supply pipe is directed so that the outlet of the source gas supply pipe is on the surface of at least one discharge electrode of the adjacent discharge electrodes, and the other discharge electrode is on an extension line in the source gas flow direction. And
The plasma CVD apparatus according to claim 1, wherein the other discharge electrode itself serves as a barrier instead of the barrier.   The plasma CVD apparatus according to any one of claims 1 to 4, wherein a shape of the discharge electrode when the discharge electrode is observed from a position where the deposition target substrate is placed is a double spiral shape.   The plasma CVD apparatus according to any one of claims 1 to 4, wherein a shape of the discharge electrode when the discharge electrode is observed from a position where the deposition target substrate is placed is a comb shape. Hold the inside of the chamber under reduced pressure,
Introducing source gas from the source gas supply pipe between adjacent discharge electrodes,
Applying alternating current or high frequency voltage with different polarity to each of the adjacent discharge electrodes to generate plasma in the source gas,
A barrier is provided between the outlet of the source gas supply pipe and an extension line in the source gas flow direction and a position where the deposition target substrate is placed,
A plasma CVD method in which the source gas is made to collide with the barrier and then reach the deposition target substrate to form a thin film on the deposition target substrate;   A substrate with a thin film manufactured using the plasma CVD method according to claim 7.

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