Influence of silicon wafer surface orientation on very thin oxide quality

Effects of silicon wafer surface orientation on very thin oxide quality were studied, testing Si(100) and (111) wafers. It has been found that the very thin oxide quality is determined by the silicon wafer surface orientation, and that when Si(111) is oxidized, SiO2/Si(111) interface microroughness increases as oxide becomes thicker than 10 nm, resulting in a degradation of oxide films quality on Si(111). When oxide thickness is decreased less than 10 nm, Si/SiO2 interface smoothness is maintained similar for Si(100) and (111) but SiO2/Si interface for Si(111) exhibits larger interface charges and larger threshold-voltage shift due to hot-electron injection than that for Si(100).