DOPING AND DAMAGE DOSE DEPENDENCE OF IMPLANT INDUCED TRANSIENT ENHANCED DIFFUSION BELOW THE AMORPHIZATION THRESHOLD

Special test structures were used to isolate the dependence of transie nt enhanced diffusion on damage dose and on doping concentration. The structures consisted of 200 nm boron-doped layers with an undoped sili con capping layer 300 nm thick. The boron concentrations varied from 5 x 10(16) to 5 x 10(18)/cm3. Damage was introduced by 75 ke V, Si impl ants with doses ranging from 1 x 10(12) to 5 x 10(13)/cm2. Annealing a t 750-degrees-C for 120 min produced a large enhancement in the boron diffusivity. The enhancement increased with increasing Si dose, but in a sublinear manner. The enhancement decreased with increasing boron d oping concentration, even for doping concentrations below the intrinsi c electron concentration. A phenomenological defect-doping reaction mo del is described which predicts both of these essential features of da mage enhanced diffusion. We conclude that it will be necessary to trea t the full coupling between defects and dopant atoms in order to model damage enhanced diffusion effects.