Study of chemical reaction and phenomena of heat and mass transfer during CZ-silicon crystal growth

用于生产大规模集成电路衬底的直拉硅单晶生长技术长期依赖于硅片制造者基于实验试验和误差的许多技术。然而，为了更灵活地适应更复杂的晶体生产操作，更有必要对直拉硅单晶的生长进行科学的探讨和讨论。本文研究了CZ-Si晶体生长过程中的高温热化学反应和热质传递现象，并注意到生长界面的氧输运和位错现象。主要研究结果如下：(1)针对石英玻璃/硅熔体界面，提出了一种新的研究直拉硅单晶生长过程中氧输运过程的方法--滴法。用滴法精确测量了石英玻璃在硅熔体中的溶解速率，得到的溶解速率比常规测量高出近一个数量级。(2)用SiO_2玻璃/硅熔体/SiO气体平衡体系测量了与直拉硅单晶生长有关的SiO蒸汽压。(3)用B原子浓度为1~7×10~(-18)原子/厘米~3的晶种，在晶种/生长界面上没有因热冲击和晶格失配而产生位错。因此，提出了无位错、无短颈生长重掺硼硅晶种的设想。

Czochralski (CZ) silicon crystal growth technology for production of LSI substrates depends on much technique based on experimental trials and errors at Si maker for a long time. However, it is more necessary to approach and discuss scientifically the CZ-Si crystal growth for corresponding flexibly to more complex operation of crystal production. In the present study, the thermochemical reaction at high temperature and the phenomenorr of heat and mass transfer during CZ-Si crystal growth have been investigated, and we noticed the oxygen transport and the dislocation at growth interface. Typical results are as follows,(1) Concerning the interface of silica glass/Si melt, a new method called drop method is proposed for understanding oxygen transportation process in the CZ-Si crystal growth. Dissolution rate of silica glass in Si melt is precisely measured using the drop method and can be obtained almost one order larger than that obtained from the conventional measurement.(2) SiO vapor pressure concerning CZ-Si crystal growth is measured by an SiO_2 glass/Si melt/SiO gas equilibrium system. It is found that the dependence of the SiO vaper pressure on temperature is good agreement with the calculated results using some thermochemical data.(3) It is found that no dislocations due to both thermal shock and lattice misfit form at a seed/grown crystal interface using a seed with 1〜7x10^<18> atoms/cm^3 of B concentration. So, dislocation-free CZ-Si crystal growth without Dash necking is proposed using the heavily B-doped Si seed.