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在选择复盖SiO_2或Si_■N_4的硅衬底上,进行了单晶硅和多晶硅的同步淀积实验。对于SiO_2-Si衬底,在相当广泛的实验条件下,观察到在SiO_2-Si边界附近存在着异常核化现象。即边缘效应,而在Si_3N_4-Si衬底上则不出现边缘效应。本文认为边缘效应的起因在于反应物沿衬底表面的水平扩散流,并提出了一个二维扩散滞流层模型。从这个模型出发,可以半定量地估计各工艺参数与边缘效应的关系,理论与实验观察很好地一致。
Simultaneous deposition experiments of single crystal silicon and polycrystalline silicon were carried out on the silicon substrate covered with SiO_2 or Si_ ■ N_4. For SiO_2-Si substrate, under a wide range of experimental conditions, abnormal nucleation near the boundary of SiO_2-Si was observed. Ie edge effect, while no edge effect appears on Si_3N_4-Si substrate. This paper argues that the origin of the edge effect lies in the horizontal diffusion flow of the reactants along the surface of the substrate and proposes a two-dimensional diffusion stagnation layer model. Starting from this model, we can semi-quantitatively estimate the relationship between the process parameters and the edge effect. The theoretical and experimental observations are in good agreement.