Patent ID: 8029874

Claim:
A gas supply method in a plasma processing apparatus, wherein the plasma processing apparatus includes a processing chamber for processing an object to be processed, a turbo molecular pump for decompressing the processing chamber, a sample holding electrode being provided in the processing chamber, a gas supply system for supplying a gas into the processing chamber, a high frequency electromagnetic radiation power supply for generating plasma in the processing chamber, and a control computer, wherein the gas supply systems includes a first gas supply path for supplying a gas into the processing chamber by way of a shower plate provided in the processing chamber, the shower plate having a back side facing the first gas supply path, and a second gas supply path for supplying a gas into the processing chamber directly, without passing through the shower plate; wherein the control computer is configured so as to be capable of adjusting flow rates of the gases from the first and second gas supply paths and selectively supplying a processing gas or a vent gas into the processing chamber; and wherein in a condition where decompressing operation for the processing chamber by the turbo molecular pump is stopped when the processing chamber in vacuum atmosphere is to be vented to atmosphere, the method comprises steps of: supplying the vent gases into the processing chamber from both the first gas supply path and the second gas supply path, while suppressing a differential pressure between a pressure in the processing chamber and a pressure on the back side of the shower plate to a pressure less than a withstand pressure of the shower plate.