Si의 식각반응을 HF-산화제-H₂O 혼합용액에서 HF 농도, 산화제 농도, 교반속도 및 식각온도 등 여러 가지 실험변수를 변화시키면서 연구하였다. 산화제의 농도에 따른 식각반응속도를 조사한 결과 KIO₃, K₂Cr₂O₇의 경우는 농도가 증가함에 따라서 식각속도가 증가하였으나, KBrO₃의 경우는 농도가 증가함에 따라서 식각속도가 증가하다가 어느 농도 이상부터는 식각된 표면에 K₂SiF₆가 성장하여 식각속도가 감소함을 알 수 있었다. 낮은 HF 농도에서는 식각속도가 낮게 일정히 유지되고, 높은 HF 농도에서는 식각속도가 갑자기 증가하는 것을 알 수가 있었다. 이로부터 HF가 식각반응동안 형성된 K₂SiF₆의 제거뿐만 아니라 Si표면에 정공(hole)의 생성속도 증가에도 영향을 미침을 확인할 수 있었다. Si식각반응의 율속단계는 Si표면에 생성되는 정공의 생성속도였으며, 식각반응속도식은 E_v-E_abs, 산화제와 HF의 농도 및 반응온도의 함수로 표시할 수 있었으며, 각 식각용액에 대해 실험적으로 결정할 수 있었다.

The reaction kinetics of silicon etching in HF-oxidizing agent-H₂O solutions has been investigated experimentally. The etch rates were examined varying HF and oxidizing agent concentrations, agitation speed, and etching temperature. The etch rates increased with increasing the concentration of oxidizing agent. In a KBrO₃-12M HF-H₂O solution, however, the rates increased to a maximum at 0.05M KBrO3 and then decreased as the KBrO₃ concentration increased. A K₂SiF₆ layer was found to be deposited on the silicon surface at high KBrO₃ concentrations. HF played an important role for accelerating the formation rate of holes at the silicon surface and for the removal rate of K₂SiF₆ formed on the wafer surface during the reaction. At low HF concentrations, the etch rate increased slightly since the formation rate of holes was very slow. Under the condition of sufficiently high HF concentrations, the higher was the energy difference between the valence band of Si and the solution potential of etchant, the lower was the activation energy and thus faster was the etch rate of Si. The rate limiting step of the silicon etching reaction was proved to be the formation of holes at the surface. The rate law of the silicon etching reaction was determined experimentally.

Silicon Wafer Wet Etching Solution Potential Reaction Kinetics K₂SiF₆

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