Impact of phase lag on uniformity in pulsed capacitively coupled plasmas

Abstract

Process uniformity of macro-scale parameters such as electron and ion densities is critical during any plasma process. Pulsed operation of multiple frequency capacitively coupled plasmas (CCPs) has been shown to improve profile characteristics of features during plasma etching. In this work, we consider pulsing of both power sources in a dual frequency CCP. The impact of phase lag between the high frequency and low frequency power pulses on plasma uniformity is examined using a two-dimensional computational plasma model. Results for Ar/CF4 gas mixture indicate that phase lag allows one to control plasma uniformity by modulating the time for which the high or low frequency source is on.