シリコン融液成長における軽元素の偏析現象 : I. 成長誘起不純物偏析現象

抄録

Unintentionally and highly doped impurities in semiconductor silicon crystals are the light elements such as carbon, nitrogen and oxygen, which are typically contained with 〜1x10_16 atoms/cm^3,<2x10^14 atoms/cm^3 (detection limit) and 〜1x10_18 atoms/cm^3, respectively. More precise control of these light element concentrations in silicon wafers will be required for the future LSI fabrications. Incorporation mechanisms of these elements into crystals during growth including the values of segregation coefficients are described which have very different properties from the III and V elements. The characteristics of these elements are as follows: 1. Carbon: There are many sources of CO gas in CZ furnaces and its introduction into the melt will be influenced by the equilibrium reaction of {C} + {O}⇔CO. { } means chemical species in the melt. It seems that carbon is incorporated into crystal as SiC. Because of SiC impurity, carbon has a small equilibrium segregation coefficient. Carbon in crystal enhances the excess vacancy concentration during growth like as boron.