Patent ID: 6618276
Filing Date: 2003-09-09
Classification: H01J,H02M

Abstract:
A plasma control system comprising:a plasma chamber excited by a radio frequency (RF) signal; a plasma controller for measuring operating conditions of the plasma chamber and generating control signals for varying conditions within the plasma chamber; and a RF generator for generating an RF signal to the plasma chamber, the RE generator including: a RF controller, the RF controller receiving the control signal from the plasma controller and generating a power supply control signal, and a power supply for receiving the power supply control signal and generating a RF signal in accordance with the power supply control signal, the power supply further including: a source of direct current (DC) voltage; a half-bridge inverter for receiving the DC input voltage and for generating an alternating current (AC) output signal; a first harmonic filter at the output of the inverter, the first harmonic filter filtering out predetermined harmonic components of the AC signal to generate a filtered AC signal; and an output circuit at the output of the first harmonic filter for receiving the filtered AC signal and feeding the filtered AC signal to a load, wherein the output circuit includes first and second rectifiers connected relative to a point in the output circuit such that if the inverter attempts to drive the point to a voltage which exceeds one of a predetermined first and second voltage, a respective one of the first and second rectifiers conducts to cause at least one of voltage and current to return to the source of DC voltage.