Conditions for the Generation of Slip by Diffusion of Phosphorus into Silicon

Abstract

On the basis of theoretical considerations it is shown that the critical surface-impurity concentration Nscrit for the generation of slip during diffusion, as well as the depth η0 to which dislocations will move, depend strongly on the impurity concentration profile. A weak dependence of Nscrit on crystal orientation has to be expected also. Nscrit has been calculated for phosphorus diffusing into silicon to be 4.11×1020 cm−3 with the reasonable assumption of a complementary error-function impurity profile. The experimental value is 2.0×1020 cm−3 <Nscrit <2.5×1020 cm−3. The theory has been used to explain details in slip patterns displayed on a {110} surface after etching the sample. Finally the markedly different appearance of slip patterns due to apparently small variations in diffusion parameters is demonstrated and discussed.