Reactive Ion Etching of GaN using Cl/BCl3

Both the improvement of GaN etching rates and the etching effect on photoresist are mainly emphasized. RF power, which is 100 W for this experiment, is determined because the surface of n-GaN wafer after dry etching process turns out fair and smooth. The n-GaN etch rate for 40 seem of BCl₃ is rapidly increased to 67 run/min when 5 seem of Cl₂ is added to the gas. The etching rate is continuously increased from Cl₂/BCl₃ = 0 to Cl₂/BCl₃ = 0.125 and then, decreased. Observation of decrease of n-GaN etch rate above Cl₂/BCl₃ = 0.125 is maybe due to retarded chemical reactions such as saturation and crowding of active ion species of Cl₂ on the GaN surface. If Cl₂ gas is added to BCI3 gas, then the etching rate of photoresist, which is even higher than the etching rate of n-GaN, is rapidly increased. This is one of the drawbacks for the dry etching process with Cl₂ gas, which is the shortcoming much attention has to be paid.