Patent ID: 7558045

Claim:
An electrostatic chuck assembly comprising: a platen configured to receive a workpiece; a clamping voltage power supply configured to generate a direct current (DC) clamping voltage for the electrostatic chuck assembly; an electrode assembly for the platen, the electrode assembly being configured to receive the DC clamping voltage to electrostatically adhere the workpiece to the platen; and a capacitive sensor subsystem coupled to the electrode assembly, the capacitive sensor subsystem being configured to generate an alternating current (AC) excitation signal for the electrode assembly, and analyze electrical characteristics of the excitation signal that are influenced by changes in capacitance between the workpiece and the platen; wherein the clamping voltage power supply comprises the capacitive sensor subsystem; and the clamping voltage power supply further comprises an adjustable DC offset voltage source configured to generate a DC offset potential for the electrode assembly.