Wj Semiconductor Equipment Group, Inc.

Andrew J Graven

Yunju Ra

Melvin Schmidt

Kenneth A McCuen

A method and apparatus for securely clamping a substrate to an electrostatic chuck during processing of a substrate. The method generally includes the steps of forming an initial electrostatic clamping force between the electrostatic chuck and the substrate, modifying the initial electrostatic clamping force when an rf voltage is applied to the electrostatic chuck during processing, and restoring the initial electrostatic clamping force with an offset voltage applied to the electrostatic chuck. The present invention also includes an electrostatic chuck having at least one electrode and a dielectric on the surface of the electrode for supporting a substrate. A voltage source is coupled to the electrode for electrostatically clamping the substrate to the surface of the electrostatic chuck with an initial electrostatic force. An rf source is coupled to the electrode for applying rf voltage to the electrostatic chuck and causing a change in the initial electrostatic force. A control system is coupled to the rf source and voltage source for producing an offset voltage in response to the change in the initial electrostatic force thereby restoring the initial electrostatic force.

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San Jose, CA, United States of America

Andrew J Graven