PURPOSE: To improve a throughput in the case of a gas chopping process by providing a moving means, through which a sample is alternately moved to and from between an etching gas plasma and a deposition gas in a treatment chamber.

CONSTITUTION: A gas introduction into a treatment chamber 1 is separately carried out through induction ports 30 and 31 and then upper and lower electrodes are periodically ascended or descended by a driving gear 4 that makes the upper electrode 2 go up and down as well as the driving gear 5 that makes the lower electrode 3 go up and down. A wafer 7 is periodically moved to and from between one region rich in the gas A and other region rich in the gas B. Since the above mechanical operation eliminates the need for changing over the gas inside of the treatment chamber and can perform continuously a gas chopping process, this approach helps improve a throughput in the case of the gas chopping process.