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

首先，提出了一种干燥化学工艺来制备定义良好的硅表面。在不破坏表面均匀性的前提下，成功地对硅表面进行氮化、硫化和氧化，在500℃以下形成氮化、硫化物和氧化物单层。目前的工作表明，这种化学改性方法适用于许多大规模集成电路工艺，因为它不需要超高真空和高温，因此比目前的技术更经济。接下来，采用WF_6和SiH_4的1:1混合物，成功地利用单层处理硅衬底阻止CVD钨生长。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。单分子膜表面处理可以改变基底表面的化学敏感性，同时保持本体性质不变，具有改进和优化薄膜制备工艺的潜力。最后，提出了用成核密度和钨膜表面覆盖率来评价不同基体表面反应性的简单模型。该模型表明，当硅表面有一层氮时，H-Si表面的反应活性降低了3个数量级。

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.