Real-time monitoring of plasma flickering in high pressure electronegative discharge

As plasma process is widely used for semiconductor fabrication, various kind of abnormal characteristics of the discharge is observed. In a high pressure discharge with electronegative gas, plasma flickering was observed and it was suspicious to cause a certain type of device failure. To understand the mechanism and to monitor its behavior according to chamber RF time, real-time monitoring using OES has been performed. Also, numerical algorithms to evaluate the degree of flickering was proposed and confirmed to be useful for monitoring wafer to wafer variation of the plasma status. A probable mechanism based on the electronegative discharge characteristics, was suggested and the plasma stability could be improved by following guidelines which was suggested through the understanding of the mechanism.