Effect of Plasma Heat flux on Cryogenic Substrate Temperature in an Inductive Discharge with RF bias power*

The effect of plasma heat flux on the substrate temperature is investigated in an inductively coupled plasma with an RF-biased substrate. The substrate temperature is determined by liquid nitrogen cooling, plasma-generated heat flux, and the thermal conductivity of the gas. It is observed that the substrate temperature increases with increasing plasma heat flux. At 5 mTorr, When the bias power is increased from 0 W to 300 W, the substrate temperature increases by 40 °C. It is due to the ion heat flux as a result of the increased bias power. However, at 60 mTorr, although the ion heat flux increases, the substrate temperature increases less than at 5 mTorr. This is because the thermal conduction cooling increases due to more gas atoms striking the substrate at 60 mTorr. These show a relationship between plasma heat flux and substrate temperature.