Point Defect Injection and Enhanced Sb Diffusion in Si During Co-Si and Ti-Si Reactions

Abstract

ABSTRACTThe effects of Co and Ti silicide film formation on diffusion of buried Sb-doped layers in Si have been investigated. Sb profile analysis by secondary ion mass spectrometry shows that greatly enhanced, non-uniform Sb diffusion occurs during reactions of various thicknesses (30- 300 nm) of Co and Ti by rapid thermal annealing. A simple non-equilibrium intrinsic diffusion model is invoked to estimate time-averaged excess vacancy concentrations. Vacancy concentrations of about 107 times equilibrium values are shown to exist during CoSi2 formation by reaction of a 30 nm Co film at 700°C for 5 min in Ar.Diffusion enhancements at large distances from silicide stripe edges are observed by bevel and etch techniques. These effects tend to decrease with increasing annealing time, indicating that film stresses may play an important role in the interfacial point defect injection process.