MECHANISM OF HF ETCHING OF SILICON SURFACES - A THEORETICAL UNDERSTANDING OF HYDROGEN PASSIVATION

Ab initio molecular-orbital theory is used to unravel the mechanism of HF etching leading to hydrogen-passivated silicon surfaces as observed experimentally. Total-energy calculations on transition states of model silicon compounds suggest that the activation barriers for HF attack of the Si surface determine the resulting surface termination. In particular, the H passivation results from efficient removal of fluorine-bonded surface silicon as SiF4 leaving behind hydrogen. © 1990 The American Physical Society.