GAS-PHASE ROOM-TEMPERATURE OXIDATION OF (100) SILICON

A microscopic model is proposed for explaining the kinetics of gas-pha se (O-2 or O-2:H2O) room-temperature oxidation of single crystalline ( 100) silicon. The formation of the first oxide layer is described in t erms of oxidation by O-2 of weak Si-Si backbonds to surface = Si(OH)(2 ) groups, The growth of a thicker oxide, which occurs in a layer-by-la yer fashion, is described as the final result of a set of hydroxylatio n-oxidation cycles, whose rate-determining step is cleavage by water o f peroxidic bridges at the Si-SiO2 interface, After the first monolaye r, this process requires thermally assisted tunnelling of the proton f rom an adsorbed H2O molecule at the SiO2 surface to an oxygen bridge a t the interface followed by OH- drift to the proton-hosting site.