US Patent 7224568 Plasma processing method and plasma processing apparatus

In a plasma processing apparatus using electrostatic chuck, increase of plasma potential is prevented and abnormal discharge is avoided. The plasma processing apparatus comprises an RF source for generating plasma in a vacuum container, another RF source for applying an RF bias power to a sample, a sample stage having an electrostatic chuck electrode, a DC power supply for applying an electrostatic chuck voltage to the electrode, and a controller for shifting the electrostatic chuck voltage to negative by a potential difference of quarter to half of peak-to-peak voltage of the RF bias power for suppressing increase of plasma potential.