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The effect of the growth rate on the microstructureof multi-crystalline silicon
This paper presents an experimental study of the influence of the growth rate on the microstructure ofmulti-crystalline silicon (mc-Si). Crystals with a diameter of 105 mm were grown from an inductivelyheated, well-mixed melt by the conventional vertical Bridgman technique. Axial and vertical samples wereprepared from the crystals to analyze the grain structure as well as the distribution of dislocations and precipitates. The results show that the growth rate influences the microstructure of the crystals mainly atthe beginning of the solidi?cation process. Growth with a low growth rate, for instance, favors theformation of radially elongated grains near the bottom of the crystal and suppresses the heterogeneousnucleation of SiC precipitates at the inner crucible wall. The effect on the grain shape is restricted to thebottom region of the crystals, whereas the precipitates are identi?ed to be the origin of dislocations ordislocation clusters propagating throughout the crystal during growth. As a consequence, the dislocationdensity in a slowly grown crystal is found to be signi?cantly lower than in a fast grown crystal.

本文提出了一項(xiàng)多晶硅晶體生長(zhǎng)速率對(duì)微觀結(jié)構(gòu)影響的實(shí)驗(yàn)性的研究，直徑105mm的晶體在感應(yīng)加熱并采用傳統(tǒng)的垂直布里奇法，混合良好的熔體中生長(zhǎng)。該樣品軸向和垂直方向被用于分析晶粒的結(jié)構(gòu)還有位錯(cuò)及沉積物的分布。結(jié)果表明生長(zhǎng)速率對(duì)于晶體微觀結(jié)構(gòu)主要在于凝固過(guò)程開(kāi)始的時(shí)候。例如，較慢的生長(zhǎng)速率容易在晶體底部生長(zhǎng)出放射狀、細(xì)長(zhǎng)的晶粒，同時(shí)會(huì)抑制碳化硅沉淀在坩堝壁上異質(zhì)形核。對(duì)晶粒形狀的影響只限于晶體的底部區(qū)域，然而，沉淀物被指出是晶體生長(zhǎng)過(guò)程中遍及晶體內(nèi)部的位錯(cuò)或者位錯(cuò)族增殖的起源。因而發(fā)現(xiàn)，緩慢生長(zhǎng)的晶體的位錯(cuò)密度顯著地低于快速生長(zhǎng)的晶體。