Anomalous diffusion of arsenic in silicon during low-temperature heat treatment

Abstract

It was found that diffusion of arsenic, and boron underneath the arsenic-diffused layer, was accelerated during low-temperature heat treatment. This diffusivity is extremely large in comparison to the normal one, and depends on the treatment time. The effective diffusion coefficients of arsenic at 700 °C are 1×10−16 cm2/sec for 5 h and 7×10−18 cm2/sec for 170 h. Such a phenomenon may be due to the excess vacancies formed during these treatments. This effect also causes the emitter dip effect in the npn transistor using arsenic for the emitter impurity.