TWI627674B

A plasma processing method which performs plasma processing on a sample by a plurality of steps includes a first step of stopping supply of gas of one step while supplying an inert gas and a second step stopping the supply of the inert gas of the first step while as supplying a gas of the other step after the first step. An amount of the gas of the one step remaining inside a process chamber in which the sample is plasma-processed is detected in the first step. An amount of the gas of the other step reached inside the process chamber is detected in the second step. The one step is switched to the other step based on the amount of the gas of the one step detected in the first step and the amount of the gas of the other step detected in the second step.