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采用垂直梯度凝固(VGF)法生长单晶时,其温度梯度较低,生长速率较小,目前已成为生长大直径、低位错密度晶体的主流技术之一。在VGF法生长单晶的过程中,籽晶的熔接工艺直接影响着单晶生长的成败。研究了拉速器速度、保温时间及石英棉用量对6英寸(1英寸=2.54 cm)锗单晶VGF生长中籽晶熔接的影响,并确定了最佳的籽晶熔接工艺。研究结果发现,当拉速器速度为3~4 mm/h、保温时间为75~100 min、石英棉用量为15~20 g时,实现了对籽晶熔接工艺的精准控制,熔接长度为12~22 mm,位错密度小于500 cm~(-2),有效地降低了生产成本,提高了生产效率和单晶率。
When single crystals are grown by vertical gradient solidification (VGF), the temperature gradient is lower and the growth rate is smaller. So far, it has become one of the mainstream technologies for growing large diameter and low dislocation density crystals. During the growth of single crystal by the VGF method, the welding process of the seed crystal directly affects the success or failure of single crystal growth. The effects of speed, holding time and dosage of quartz wool on the fusion of seeds in 6-inch (1 inch = 2.54 cm) germanium single crystal VGF were studied, and the best technology of seed fusion was determined. The results show that when the speed of the pull-up device is 3 ~ 4 mm / h, the holding time is 75 ~ 100 min and the dosage of quartz wool is 15 ~ 20 g, the precise control of the seed crystal welding process is realized. The welding length is 12 ~ 22 mm, dislocation density less than 500 cm ~ (-2), effectively reducing the production cost and improving the production efficiency and single crystal rate.