Mechanistic study of silicon etching in HF-KBrO sub(3)-H sub(2)O solution

The chemical etching of silicon in HF-KBrO sub(3)-H sub(2)O mixed solution has been investigated experimentally. The etch rates were examined with varying HF and KBrO sub(3) 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 K sub(2)SiF sub(6) 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 K sub(2)SiF sub(6) layer. For high HF concentration, we suggest that the rate-determining step of the reaction was the formation of holes at the silicon surface.