Patent ID: 6291999
Filing Date: 2001-09-18
Classification: H01J,H05H

Abstract:
A plasma monitoring apparatus for monitoring a status of a plasma load, comprising:a high frequency power supply for supplying high frequency power to the plasma load;an impedance matching circuit coupled between the high frequency power supply and the plasma load, said impedance matching circuit having a load-side terminal connected to the plasma load;a voltage detector for detecting a voltage at the load-side terminal of the impedance matching circuit;a current detector for detecting a current at the load-side terminal of the impedance matching circuit;a phase difference detector for detecting a difference in phase between the voltage detected by the voltage detector and the current detected by the current detector;an input impedance calculator for calculating a first impedance at the load-side terminal of the impedance matching circuit, based upon the detected voltage, the detected current and the detected phase difference; anda plasma impedance calculator for calculating a second impedance of the plasma load, based upon both the first calculated impedance and a measured impedance of a line coupled between the load-side terminal of the impedance matching circuit and the plasma load.