Heat transfer between wafer and electrode in a high density plasma etcher

Heat transfer between a wafer and electrode has been studied in a planar-type inductively coupled plasma reactor in terms of temperatures of wafer, chamber wall and electrode. A substantial increase in the wafer temperature was attributed mainly to bombardment of incident ions onto the wafer surface. The decrease in the wafer temperature at a higher pressure was attributed to the decrease in plasma density and a resistance to heat transfer in a micro gap formed between the wafer and the electrode. Compared to the case of no rf-chuck power applied, the wafer temperature when the electrode was biased with 13.56 MHz if power showed a greater increase mainly due to increased ion bombardment. Since the electrode having a water-cooled-backside geometry gains heat from the bulk plasma, it may lead to fast etch rates of hard materials whose etch products are less volatile at low temperatures, but not be good for photoresist materials.