| 摘要 |
PURPOSE:To remove impurities in gas introduced into a vacuum chamber and improve the uniformity of an etching rate by a method wherein the gas is preliminarily cooled to a temperature below the temperature of a sample before the gas is introduced into the vacuum chamber or the gas to be introduced into a treatment chamber is made to form a plasma by discharge before the gas is introduced into the treatment chamber. CONSTITUTION:A parallel plate type radio frequency discharge plasma etching system is composed of a low temperature sample table 7 which controls the temperature of a sample 8 below the temperature of water, a plasma generating part and a post- treatment chamber 2. When gas is introduced, the gas is preliminarily supplied to a gas cooling part 24 from a gas supply system 25 before the gas is supplied to the plasma generating part. While the sample temperature is maintained at -160 deg.C, the number of impurity particles which are deposited on the surface of the sample and obtained when F2 gas is introduced over the sample is obtained as a function of the temperature of the gas cooling part 24. The most of the impurity particles are made of ice. As a result, the closer to -160 deg.C the temperature, the fewer the number of impurity particles. Therefore, the method wherein the gas introduced into the low temperature etching chamber after it is cooled is very effective for reducing impurity particles.
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