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.