Experimental evidence for the presence of segregation and relaxation gettering of iron in polycrystalline silicon layers on silicon

摘要

Experimental evidence is provided that gettering of iron by polycrystalline silicon (polysilicon) is driven by a combination of two gettering mechanisms, segregation and relaxation. The segregation coefficient of iron in polysilicon in samples annealed at temperatures between 1020 and 1175℃ varied from approximately 16 to 2. The efficiency of relaxation gettering by polysilicon was characterized using Ham's model of diffusion-limited gettering. The product nr_(0) for the 11-μm-thick polysilicon layer was estimated as 10~(6) cm~(-2).