SiO2 etching using M=0 helicon wave plasma

When applying high-density plasma to SiO2 etching, the ability to control the degree of dissociation is critical. In this study, two methods for controlling the degree of dissociation were evaluated using M = 0 helicon wave plasma. One method was time-modulated discharge and the other adjusting the source power in the conventional continuous discharge. It was concluded that almost identical etching characteristics could be obtained, at least in M = 0 helicon wave plasma, if and only if the applied source power in the continuous discharge was equal to the net source power in the time-modulated discharge. The probe measurement revealed that the electron temperature did not change with increasing source power; however, the emission spectroscopic study indicated that the high-energy tail of the electron-energy distribution function grew with increasing source power. This is considered to be the cause of the high degree of dissociation.