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

首先，提出了一种用于制备轮廓分明的Si表面的干化学工艺。在低于500 ℃的温度下，氢封端的硅表面被成功地氮化、硫化和氧化，以形成氮化物、硫化物和氧化物的单层，而不破坏表面均匀性。本工作表明，这种化学改性方法适用于许多LSI工艺，因为它不需要超高真空或高温，因此比现有技术更经济。其次，使用WF_6和SiH_4的1：1混合物，单层处理的硅衬底成功地用于防止CVD钨生长。衬底的XPS分析表明，在单层氮化硅上的沉积速率与在热生长的mm氧化硅膜上的沉积速率一样低。单层表面处理可以在保持衬底本体性质不变的情况下改变衬底表面的化学敏感性，具有改善和优化薄膜制备工艺的潜力。最后，提出了一个简单的模型，通过钨膜的成核密度和表面覆盖率来评价不同衬底的表面反应性。该模型表明，H-Si表面的反应性降低了3个数量级的硅表面上的氮单层。

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.