シリコンの融液成長(<特集>Growth and Characterization of Silicon Crystals)

抄録

Crystal growth of silicon is discussed on the basis of in situ X-ray topographic observation in order to obtain a general view of interface structure in melt growth. The effect of dislocations on the faceted growth indicates that Si crystals (Jackson's parameter = 2.7) grow with singular sharp interfaces. However, the in situ observation of the growth interfaces and the dependence of impurity incorporation on the interface orientation lead to the conclusion that a supercooled layer with an intermediary structure between the crystal and melt exists on the melt-side of the interface in growth processes. This layer seems to play an important role in formation of growth bandings and propagation of dislocations. The in situ observation shows that dislocations generally cannot intersect with growth interfaces. This fact is probably due to the presence of the supercooled layer. Dislocations propagate into newly grown dislocation-free regions after the interface proceeds. On the other hand, melting interfaces have a superheated layer on their crystal-side where crystal perfection is degraded : An example is the formation of liquid droplets in the layer which results in microdefects, i.e., swirl defects in dislocation-free crystals are considered to be formed during remelt periods of the growth.