I n s i t u patterning of GaAs by focused ion beam

Abstract

We have investigated the characteristics of ion beam induced spontaneous etching (IBISE) of GaAs by 15 keV Ga focused ion beam (FIB) irradiation and Cl2 gas. The area irradiated by the FIB showed high spontaneous etch rate to the exposure to Cl2 ambient. It was observed that the spontaneous etching depends on the residual H2O partial pressure. At H2O partial pressure less than 6×10−7 Torr, the threshold dose to observe IBISE was about 1015 ions/cm2 at a substrate temperature of 100 °C. However, at H2O partial pressure of 3×10−6 Torr, the threshold dose decreased below 1014 ions/cm2 at a substrate temperature of 90 °C. The small amount of H2O in Cl2 gas effectively decreases the threshold dose resulting in a reduction of radiation damage of the substrate and increasing the processing rate.