MECHANISTIC STUDY OF SILICON ETCHING IN HF-KBRO3-H2O SOLUTION

The chemical etching of silicon in HF-KBrO3-H2O mixed solution has been investigated experimentally. The etch rates were examined with varying HF and KBrO3 concentrations, agitation speed, and etching temperature. The etch rates were similar for both n- and p-type Si(100). HF played an important role for accelerating the formation rate of holes at the silicon surface and the removal rate of K2SiF6 formed on the wafer surface during the reaction. A comprehensive mechanism for the surface species formation and the silicon etching as a function of etchant concentration was developed. The holes formed at the silicon surface accelerated the etch rate and the formation of the K2SiF6 layer. For high HF concentration, we suggest that the rate-determining step of the reaction was the formation of holes at the silicon surface.