CHF_3BCl_3 reactive ion etching if AlGaAs/GaAs heterostructures

摘要

SThe selective dry etching between the AlGaAs and gaAs heterostructures in an essential issue for process controllability in heterojunction device fabrication. The mixture of CF_4 and BCl_3 has been recently proposed to replace the role of CCL_2F_2 used in AlGaAs/GaAs heterostructure etching process, where the nonvolatile AlF_3 compound is formed to prevent the further etching in AlGaAs films. In this study, we systematically changed the mixing gas ratio between chlorine-base and florine-base gases, and investigated this influence on etching selectivity in alGaAs and gaAs materials. Both CF_4+BCl_3 and CHF_3+BCl_3 gas ixtures were used, and the surface damage cuased by the plasma bombardment in these two individual gas system was also included. Finally, we used these two characterized gas mixtrues to etch away the n~+ GaAs layer in gate recess process or conventional GaAS MESFET fabrication. The result shows that CHF_3+BCl_3 gas mixture has demonstrated a lower surface damage, and was more suitable for the ate recess process.