COMPARING REACTIVE ION ETCHING OF III-V COMPOUNDS IN CL-2/BCL3/AR AND CCL2F2/BCL3/AR DISCHARGES

The reactive ion etching (RIE) of GaAs, AlGaAs, InP, InGaAs, InGaAsP in Cl-2/BCl3/Ar or CCl2F2/BCl3/Ar discharges is investigated as a function of the plasma parameters: power, pressure, and relative composition as well as etching time. For the reason of In-based fluoride with high boiling point, the etching rates of all of these materials are faster in Cl-2/BCl3/Ar in comparison to CCl2F2/BCl3/Ar. The In-based compounds show a similar dependence on power density and discharge composition, but it is quite different from GaAs. When discharges containing CCl2F2 are used, the surface morphologies are quite rough after the treatment of RIE with either type of discharge, although smooth etching surfaces can be obtained under appropriate conditions. Using BCl3 containing gas discharges will enhance smooth surface and maintain high etching rate. For selective etching of GaAs on AlGaAs, gas mixtures containing CCl2F2 are used. High performance and high selective etching can be obtained by using CCl2F2/BCl3/Ar gases mixtures. Photoresist or SiO2 were used as etching masks. Silicon dioxide is better than the photoresist mask for its low etching rate and sputtering to III-V compounds, and it could be in situ removed by CF4 plasma. The photoluminescence measurements show high performance of etched results when the power density was maintained at less than 0.6 W/cm(2).