Mobility study on RIE etched silicon surfaces using SF/sub 6//O/sub 2/ gas etchants

A methodology for the measurement of the inversion layer mobility on trench gate structures, which allows independent measurement of the sidewall and bottom surface mobilities, is described. Using this method, the inversion layer mobility has been experimentally studied for trenches formed using the SF/sub 6//O/sub 2/ method on diffused base regions of power UMOSFETs. The effect of several post RIE surface treatments on the surface mobility is reported. The measured sidewall mobilities have been found to be comparable to those previously reported for other RIE etchants. These results are of interest for the design of devices using the trench gate (UMOS) technology.>