IBA STUDY OF THE GROWTH MECHANISMS OF VERY THIN SILICON-OXIDE FILMS -THE EFFECT OF WAFER CLEANING

The growth mechanisms of very thin silicon oxide films formed during r apid thermal oxidation were studied using ion beam analysis and O-18 i sotopic tracing methods. In this paper we report on the effects of dif ferent cleaning procedures of silicon wafers prior to oxidation in dry oxygen (O-16(2) followed by O-18(2)) on the growth mechanisms and kin etics. Typical oxide thicknesses ranging from 0.2 to 10 nm were studie d. The O-18 and O-16 isotopic profiles were determined by ion beam ana lysis methods, namely: the O-18(p, alpha)N-15 narrow resonance at 151 keV, and the O-18(p, alpha)N-15 and the O-16(d, p)O-17 reactions assoc iated with step-by-step chemical dissolution. The profiles could be re lated to current theories on the initial stages of thermal growth of s ilicon oxide layers allowing us to draw some conclusions regarding the role of surface cleaning of the silicon wafers on the formation of si licon fragments in the volume of the very thin oxide layer. The influe nce of rapid thermal processing parameters like temperature, time and oxygen partial pressure on the growth mechanisms were also studied and discussed here.