Study of copper silicide retardation effects on copper diffusion in silicon

A B-buried layer with a dose of 1 x 10(14) atoms/cm(2) was introduced into p-doped Si at a depth of 2.2 Am to enhance copper diffusion via its inheren t gettering effect. Copper was then introduced into silicon either via a lo w-energy implantation followed by a thermal anneal, or through the thermal drive in of physical vapor deposited (PVD) copper film. Secondary ion mass spectrometry depth profiling of both annealed samples later indicated that while substantial amounts of copper was gettered by the B layer in the form er sample, no copper was gettered by the B-buried layer in the latter sampl e. Further analysis with an x-ray diffraction technique showed that copper silicide, Cu3Si was formed in the latter sample. It is thus surmised that t he formation of this silicide layer impeded the diffusion of copper towards the B-buried layer. This work investigates the cause of CuSix formation an d the underlying reasons for the lower mobility of Cu in PVD Cu film sample s. (C) 2001 American Institute of Physics.