Suppression of topography dependent charging using a phase-controlled pulsed inductively coupled plasma

The topography dependent charging (TDC) potential on the bottom of an oxide contact is measured with an in-situ charge-up monitoring wafer during plasma processing. The effects of the contact aspect ratio and the bias power on the TDC are investigated from the potentials measured on that wafer. By analyzing the potentials, we correlate the TDC to the difference of the charging potentials between a shading and a blank probe. We can suppress TDC considerably using a phase-controlled pulsed inductively coupled plasma, especially when the phase delay of the bias power relative to the source power is near 180° (out-of-phase condition)