Patent ID: 7767053

Claim:
A substrate processing apparatus, which has a high frequency power supply part with a controllable high frequency power source, applies a high frequency power from the high frequency power source to a discharge electrode provided in a processing chamber through a matching unit, and generates a plasma in the processing chamber, comprising: a detector that detects a traveling wave of the high frequency power applied to the discharge electrode and a reflected wave of the high frequency power reflected from the discharge electrode between the high frequency power source and the matching unit, or between the matching unit and the discharge electrode; and a controller that controls the high frequency power source so as to temporarily stop or temporarily decrease an application of the high frequency power to the discharge electrode, in accordance with a detection result of the reflected wave, wherein the detector: outputs a level detection signal when the level of a detection output of the reflected wave is more than a level set value, and outputs a differential detection signal when the level obtained by differentiating a detection output of the reflected wave is more than the differential set value, and a fluctuation of the reflected wave is thereby detected, and delays a detection output of the traveling wave for a predetermined time period, and the controller: controls the high frequency power source so as to temporarily stop or temporarily decrease an application of the high frequency power to the discharge electrode, when the level detection signal and the differential detection signal are simultaneously output from the same detector, and when the high frequency power is applied again after temporarily stopping or temporarily decreasing the application of the high frequency power to the discharge electrode, controls the high frequency power source so as to continuously apply the high frequency power without temporarily stopping or temporarily decreasing the application of the high frequency power before the predetermined time period passes in accordance with a delaying result of the traveling wave, and after the predetermined time period passes, temporarily stop or temporarily decrease the application of the high frequency power to the discharge electrode when the level detection signal and the differential detection signal are simultaneously outputted from the detector.