RF SYSTEMS AND METHODS FOR FREQUENCY MODULATION OF RADIOFREQUENCY POWER SUPPLY FOR CONTROLLING PLASMA INSTABILITY

摘要

The wafer is positioned on a wafer support device beneath the electrode so that the plasma generation region is between the wafer and the electrode. The RF signals of the first signal frequency are fed into the plasma generation region to produce a plasma within the plasma generation region. The formation of plasma instability is detected in the plasma based on the supply of RF signals at the first signal frequency. After detection of the formation of the plasma instability, RF signals of a second signal frequency are supplied into the plasma generation region in place of RF signals of the first signal frequency to generate a plasma. The second signal frequency is set to be greater than the first signal frequency and cause a corresponding decrease in secondary electron emission from the wafer caused by ion energy reduction in the plasma and ion interaction with the wafer.