JPH03140469A - Device for plasma chemical vapor growth - Google Patents

Abstract

PURPOSE:To prevent the abnormal discharge at the corner and to reduce the deposition of particles and abnormal film thickness by introducing a gas into a chamber from a shower head of the upper electrode with the corner rounded and generating a plasma discharge to cause chemical growth. CONSTITUTION:A wafer 6 is placed on a susceptor 3 which is transiently lowered, then raised and set at a specified position in a reaction vessel 1. A gas is then introduced from the shower head provided to the upper electrode 2. A high-frequency power is supplied to the upper electrode 2 from a high-frequency power source 4 to generate a plasma discharge, the gas is subjected to a reaction, and a thin film is formed on the surface of the wafer 6. The unreacted and reacted gases are discharged from an exhaust line 5 by a vacuum pump. In this plasma chemical vapor growth device, the corner (b) of the upper electrode is rounded, an electric field is concentrated on the corner, and an abnormal discharge such as an arc discharge is not caused. Consequently, the deposition of particles on the wafer 6, abnormal film thickness on the peripheral part of the wafer 6, etc., are reduced, and the yield in the production of a semiconductor device is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a plasma chemical vapor deposition apparatus that utilizes plasma discharge.

<Prior art> Figure 2(a) shows a single wafer type plasma CV according to the conventional technology.
A schematic cross-sectional view of device D, and FIG. 2(b) shows an enlarged view of the corner portion of the upper electrode. The plasma CVD apparatus includes a reaction vessel 1 equipped with a vacuum reaction chamber, a disk-shaped upper electrode 2 formed of aluminum or stainless steel and coated by anodic oxidation, and a lower electrode that faces the upper electrode 2 and is movable up and down. It consists of a susceptor 3, an exhaust line 5 with an exhaust pipe 7, and a high frequency power source 4. As shown in FIG. 2(b), the corners of the upper electrode 20 are steep.

Further, the wafer 6 is placed on the susceptor 3. In order to make the film thickness uniform in this single-wafer type chamber, a method is often used in which the upper electrode 2 is introduced into the chamber by a shower head having a structure with many holes as shown in Fig. 3. .

In this apparatus, first, the susceptor 3 is lowered, and the wafer 6 is placed on the susceptor 3 by a robot (not shown). Next, after the susceptor 3 rises to a preset distance between the susceptor 3 and the upper electrode 2, gas is introduced into the chamber 2 from the shower head of the upper electrode 2, and high-frequency power is applied to the upper electrode 2 and the susceptor 3. As a result, plasma is generated and a thin film is grown on the wafer 6.

Unreacted and post-reacted gases are exhausted from an exhaust pipe 7 by a vacuum pump (not shown) connected to the exhaust line 5. After the thin film has grown in this way, the susceptor 3 descends,
The wafer 6 is placed in a predetermined position again by a robot (not shown).

<Problems to be Solved by the Invention> In the conventional plasma chemical vapor deposition apparatus, when high frequency power is applied to the upper electrode and the susceptor,
As shown in FIG. 3, the electric field concentrates at the corner 10 of the upper electrode, causing abnormal discharge such as arc discharge. This abnormal discharge causes particles and abnormal film thickness around the corners of the upper electrode. The present invention solves these problems.

Means for Solving the Problems> The plasma chemical vapor deposition apparatus of the present invention is a plasma chemical vapor deposition apparatus in which the upper electrode is equipped with a shower head for introducing gas into the chamber. Round (characterized by being processed.

Effect> In the plasma chemical vapor deposition apparatus of the present invention, by rounding the corners of the upper electrode, the electric field is not concentrated at the corners of the upper electrode, and therefore abnormal discharge such as arc discharge does not occur.

<Example> Fig. 1(a) is a schematic cross-sectional view of a single-wafer type plasma CVD apparatus which is an embodiment of the present invention, and Fig. 1(b) is an enlarged view of the corner portion of the upper electrode. . Plasma CVD equipment is
Inside a reaction vessel 1 equipped with a vacuum reaction chamber, a disk-shaped upper electrode 2 made of aluminum or stainless steel and coated by anodization, a susceptor 3 which is a lower electrode that faces the upper electrode 2 and is movable up and down, and It consists of an exhaust line 5 equipped with an exhaust pipe 7 and a high frequency power source 4. Further, the wafer 6 is placed on the susceptor 3. In the 20-sheet type chamber, in order to make the film thickness uniform, gas is introduced into the chamber using a shower head having a structure in which the upper electrode 2 has a large number of holes as shown in FIG. 3.

In this apparatus, first, the susceptor 3 is lowered, and the wafer 6 is placed on the susceptor 3 by a robot (not shown). Next, after the susceptor 3 rises to a preset distance between the susceptor 3 and the upper electrode 2, gas is introduced into the chamber 2 from the shower head of the upper electrode 2, and high-frequency power is applied to the upper electrode 2 and the susceptor 3. By doing so, plasma is generated and a thin film is grown on the wafer 6.

Unreacted and post-reacted gases are exhausted from an exhaust pipe 7 by a vacuum pump (not shown) connected to an exhaust line 5. After the thin film has grown in this manner, the susceptor 3 is lowered, and the wafer 6 is placed at a predetermined position by a robot (not shown).

The difference from the prior art is that the corners of the upper electrode are rounded to prevent the electric field from concentrating on the corners of the upper electrode, as shown in FIG. 1(b).

FIG. 4 shows the number of particles generated according to the present invention in comparison with that of the conventional method. As is clear from this graph, according to the present invention, the number of particles generated is reduced compared to the conventional method.

<Effects of the Invention> As described above, according to the present invention, an electric field is not concentrated at the corners of the upper electrode, so abnormal discharge such as arc discharge does not occur. Therefore, adhesion of particles onto the wafer and film thickness abnormalities occurring in the periphery of the wafer are reduced, and the performance of the semiconductor device is improved, such as the yield in manufacturing the semiconductor device is improved.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic cross-sectional view of a plasma CVD apparatus according to an embodiment of the present invention, FIG. 1(b) is an enlarged view of a corner portion of the upper electrode, and FIG. 2(a) is a conventional plasma CVD apparatus. A schematic cross-sectional view of the CVD apparatus, FIG. 2(b) is an enlarged view of a corner portion of the upper electrode, and FIG. 3 is a front view and a side view of the upper electrode of a conventional plasma CVD apparatus as viewed from the direction of the lower electrode. FIG. 4 is a graph showing the number of particles generated in the conventional method and the present invention.・Reaction vessel, upper electrode, susceptor, high frequency power supply, exhaust line 6 ・Wafer, exhaust pipe, corner of upper electrode

Claims (1)

[Claims] A plasma chemical vapor deposition apparatus comprising a shower head on an upper electrode for introducing gas into a chamber, characterized in that corners of the upper electrode are rounded.