ECR/MAGNETIC MIRROR COUPLED PLASMA-ETCHING OF GAAS USING CH4-H-2-AR

A study of CH4:H2:Ar microwave ECR-plasma etching of GaAs is presented. GaAs etch rates are measured as a function of the constituent gas flow rates, applied RF and microwave powers, substrate temperature and magnetictable separation. The results indicate that for CH4:H2:Ar ECR etching of GaAs, etch rates of 25 nm min-1 can be achieved. The electrical 'damage' in a GaAs/AlGaAs HEMT Hall bar structure was investigated by etching off the GaAs capping layer. Results indicate that ECR-plasma etching with an additional RF-table bias in the range of -40 to 0 V does not significantly increase the source-drain resistances, measured at 300 K, to that of a wet etched sample. Some degradation in n and mu was found at 1.2 K.