부산대학교 도서관

The diffusion of boron from polycrystalline silicon into single crystal silicon has been measured for average boron concentrations in the polysilicon ranging from 1 X 10/sup 20/ to 7 X 10/sup 20/ atoms/cm/sup 3/. Oxygen and carbon contamination levels at the poly/single crystal silicon interface were also measured and were found to be low enough so that the boron diffusion is not affected. The boron concentration, C/sub s/ on the single crystal silicon side of the interface is independent of the diffusion time when either boron-implanted or in situ doped polysilicon is used. For highly doped polysilicon films, C/sub s/ is also independent of the boron concentration in the polysilicon and in good agreement with the boron solubility in the range from 800/sup 0/ to 1000/sup 0/C. For diffusions at 950/sup 0/C, C/sub s/ decreases slightly when the boron concentration in the polysilicon is decreased below 2.5 X 10/sup 20/ atoms cm/sup 3/. However, large changes in the boron penetration depth, x/sub j/, in the single crystal were measured for small changes in C/sub s/.