Effects of High Phosphorus Concentration on Diffusion into Silicon

Abstract

Phosphorus diffusion into silicon has been explored near and above the solubility limit by radiochemical profiling and compared with crystal damage by x-ray diffraction microscopy and SirtI etch techniques. An apparent dif- fusion retardation has been found for very high source concentrations that results in a shallowed junction penetration for certain higher surface con- centrations. The retardation phenomenon occurs over a narrow range of sur- face concentrations, within which diffused junctions are nonuniform, or ragged. This effect can be correlated with large amounts of crystal disorder inside the diffused area and dislocation loops outside at the peripheries. These outside loops have been found to degrade transistor gain. Phosphorus