RESIDUAL DAMAGE EFFECTS ON GATE CONTACTS FORMED ON SIC SURFACES ETCHED BY USING THE AMORPHIZATION TECHNIQUE

A trench fabrication process has been proposed and experimentally demo nstrated for silicon carbide using the amorphization technique. In the present work, the quality of gates [oxide for metal oxide semiconduct or field-effect transistors (MOSFETs) and Schottky barrier contacts fo r metal semiconductor field-effect transistors (MESFETs)] fabricated o n the etched surfaces are compared with those formed on the as-grown s ilicon carbide surface. The resistivity and breakdown electric field o f the thermal oxide grown on the etched surface was found to be compar able to that of thermal oxide grown on silicon. However, a large conce ntration of acceptor type interface states (0.5-1 x 10(13) cm(-2)eV(-1 )) was observed. This results in a large negative interface charge at room temperature and a significant shift, in flat band voltage as a fu nction of temperature, which makes the process unsuitable for formatio n of gates in UMOSFETs. Titanium Schottky contacts formed on the etche d surface showed superior reverse current voltage characteristics and higher breakdown voltages than the Schottky diodes formed on unetched surface with similar doping concentrations. This indicates that the ar gon implant process for trench formation is suitable for fabrication o f gate regions in high voltage vertical MESFETs (or SITs).