Monolayr Treatment of Silicon Surfaces for Controlling the lnitial Stages of Thin Film Preperation

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First, a dry chemical process for preparing well-defined Si surfaces is proposed. Hydrogen-teminated silicon surfaces were successfully nitrided, sulfided, and oxdized to form monolayr of nitride, sulfide, and oxide below 500ﾟC,without destroying the surface uniformity. The present work suggests that this chemical modification method is applicable to many LSI processes because it does not require ultra-high-vacuum nor high temperatures, thus making it more economical than current techniques.Next, monolayr treated silicon substrates were successfully used to prevent CVD tungsten growth, using a 1 : 1 mixture of WF_6 and SiH_4. XPS analysis of the substrates showed that the deposition rate on the monolayr nitrided silicon was as low as that on the thermally grown mm silicon oxide film. Monolayr surface treatment, which modifies the chemical sensitivity of substrate surfaces while keeping the bulk properties unchanged, has potential to improve and optimize thin-film preparation processes.At last, a simple model was proposed to evaluate the surface reactivity of the different substrate using the nucleation density and the surface coverage by tungsten film. This model showed that the reactivity of H-Si surface decreases by a order of 3 with a monolayr of nitrogen on the silicon surface.