Patent ID: 6361645
Filing Date: 2002-03-26
Classification: H01J,H01L

Abstract:
A bias compensation device for compensating a bias voltage on a wafer disposed in place over an electrostatic chuck in a processing chamber of a plasma processing system, the plasma processing system including an electrostatic and RF power supplies that are coupled to the electrostatic chuck, the bias compensation device comprising:a voltage converter coupled to the electrostatic chuck for detecting a voltage Vpp of the electrostatic chuck, the voltage converter converting the detected voltage to a lower voltage Vref; a storage unit for storing a predetermined slope and a predetermined offset of a calibration curve, the calibration curve derived by fitting a plurality of wafer bias voltages as a function of electrostatic chuck voltages from a test wafer; and a voltage adjusting circuitry coupled to receive Vref from the voltage converter, the voltage adjusting circuitry also being coupled to receive the slope and the offset from the storage unit such that the voltage adjusting circuitry modifies Vref by the slope and the offset to compensate for the bias voltage, the voltage adjusting circuitry transmitting the modified Vref to the electrostatic chuck power supply, which converts the modified Vref into a bias compensated voltage for input to the electrostatic chuck so as to substantially compensate for the bias voltage on the wafer.