Control of plasma density with broadband RF sensor

摘要

A plasma processing system has a chamber, a workpiece holder in an interior of the chamber, a first power circuit, a second power circuit, and a feedback circuit. The first power circuit has a first power supply coupled to a first matching network. The first matching network is coupled to a coil adjacent to the chamber. The second power circuit has a second power supply coupled to a second matching network. The second matching network is coupled to the workpiece holder. The feedback circuit includes a radio frequency (RF) probe and a controller. The RF probe is partially disposed in an interior of the chamber. The controller is coupled to the RF probe and the first power circuit. The RF probe measures a change in plasma density in the interior of the chamber and the controller adjusts the first power supply in response to the change in plasma density.