Suboxide characteristics in ultrathin oxides grown under novel oxidation processes

Interfacial suboxide (SiOx,0<x<2) between Si and its stable SiO2 is observed to be a key factor to affect the ultrathin-oxide quality. SiO2 grown by anodic oxidation (anodization) or by repeated-spike oxidation (RSO) presents a better dielectric characteristic than conventional rapid-thermal oxidation (RTO). This improvement can be attributed to two reasons: (1) A thinner transition region and/or (2) more stoichiometric S–O bonds under the same oxide thickness. Anodic SiO2 presents a thinner suboxide width (interface region) and RSO SiO2 demonstrates the existence of less suboxide existence at the near-surface region (oxide bulk). The reduction of the imperfect bonding structure in suboxide gives an abrupt Si–SiO2 interface and consequently, the reduction of electron tunneling probability through oxide.