A CONTINUOUS AND GENERAL-MODEL FOR BORON-DIFFUSION DURING POSTIMPLANTANNEALING INCLUDING DAMAGED AND AMORPHIZING CONDITIONS

A model is presented for boron diffusion after ion implantation, The a im is to derive a formulation valid for a large range of implantation doses and annealing temperatures, In particular, it allows for the fir st time a continuous simulation of the transition between amorphizing and nonamorphizing conditions, Transient-enhanced diffusion and activa tion aspects are addressed through a physical approach, This includes a point-defect based formulation with a special emphasis on the initia l conditions in order to reproduce the effects of damaging or amorphiz ing implants, with, in the latter case, solid-phase epitaxy, It is the n shown that the initial level of activation is one of the most import ant parameters in such an analysis, in some cases overriding the influ ence of the initial amount of point-defects, On the other hand, a prec ipitation model describes the evolution of the active boron concentrat ions during the diffusion steps, The calculation results are compared satisfactorily with numerous experimental profiles, suggesting that th e overall approach enables a correct modeling of the involved phenomen a, without an explicit formulation of the extended defects kinetics, F inally, the model is validated through the simulation of the emitter/b ase region of PNP devices, with the emitter formed by various BF2 impl ant doses.