Patent ID: 7244475

Claim:
A plasma processing apparatus comprising: a vacuum container ( 2 ) in which a substrate is processed with use of a plasma gas; a plasma generation electrode ( 5 ) which is provided in said vacuum container; a high frequency power source ( 51 ) which generates a high frequency electricity to be supplied to said plasma generation electrode ( 5 ); an impedance matching device ( 34 ) which matches an input impedance of said plasma generation electrode ( 5 ) and an output impedance of said high frequency power source ( 51 ); an impedance sensor ( 42 ) which measures a level of an input impedance of said impedance matching device; a frequency control circuit ( 45 ) which controls an oscillation frequency of said high frequency power source based on a measurement result from said impedance sensor; and a phase difference sensor ( 41 ) which measures a phase difference between a voltage component and a current component of an electricity to be supplied to said impedance matching device, wherein said frequency control circuit ( 45 ) controls the oscillation frequency of said high frequency power source based on measurement results from said phase difference sensor and said impedance sensor.