The saturation effect of etch depth at high RF power in CF/sub 4/ plasma RIE silicon etching

The work presented here shows the effects of RF power of an RIE system on silicon etching. A p-type silicon [100] wafer is etched under four RF power levels, which are 40, 60, 80 and 100 W. The etch depth plotted shows a linear increase with RF power for a fixed etch time at low RF power. However, the etch depth shows a tendency to saturate at a higher RF power level. The behaviour is believed to be caused by the existence of a sheath layer when plasma is generated in the process chamber.