Results are presented for the etching of W and
WSix
in
Cl2
and
Cl2/BCl3
plasmas. Etch rates were measured for conditions ranging from 0.1 to 1.0 torr pressure, 30° to 170°C electrode temperature, 0.2 to 1.0 W/cm2 power density, and 3 to 200 sccm flow rate. Etch rates varied from below 10 nm/min to 90 nm/min for tungsten and to 450 nm/min for the silicide. Residence time effects on tungsten etching were also studied. Small additions of
BCl3
significantly increased the etch rates of both W and
WSix
and improved the reproducibility. Results suggest that chemical processes have a significant effect on etch characteristics, despite the low vapor pressure of
WCl5
and
WCl6
.