シリコン結晶成長時の気液界面の新たな理解と制御に向けて : シリコン(<特集>21世紀を担うバルク単結晶)

抄録

Silicon melt surface plays a significant role as a drain for oxygen transport from the melt to space during crystal growth by the Czochralski method. Also at the melt surface Marangoni flow takes place. However, there has been no microscopic explanation on behavior of the melt surface. Marangoni convection visualization experiment under microgravity and precise measurement of surface tension and its temperature coefficient in an ambient atmosphere with various oxygen partial pressures show possibility that the silicon melt surface can be modified with adsorbed oxygen atoms or a thin oxide layer depending on oxygen partial pressure. Marangoni flow might be different between crystal growth by the Czochralski method with a SiO_2 Crucible and that by the floating zone method free from crucible. In order to obtain a microscopic understanding of the silicon melt surface, several novel techniques should be employed, so that a new technology to control oxygen behavior during crystal growth can be obtained.