Patent attributes
Methods of monitoring a plasma while processing a semiconductor substrate are described. In embodiments, the methods include determining the difference in power between the power delivered from the plasma power supply and the power received by the plasma in a substrate processing chamber. The power received may be determined using a V/I sensor positioned after the matching circuit. The power reflected or the power lost is the difference between the delivered power and the received power. The process may be terminated by removing the delivered power if the reflected power is above a setpoint. The VRF may further be fourier transformed into frequency space and compared to the stored fourier transform of a healthy plasma process. Missing frequencies from the VRF fourier transform may independently or further indicate an out-of-tune plasma process and the process may be terminated.
