Sensitivity of PNP Doping Profiles to Annealing Conditions - Role of Dynamic Clustering Phenomena

It is well-known that doping profiles of PNP transistors are extremely sensitive to the exact annealing conditions, in particular to the ramp-up procedure. This is essentially due to the strong response of boron and phosphorus to transient-enhanced diffusion and the coupling between the two dopants [1]. In this paper, it is shown that for high boron concentration in the emitter, the dynamic behaviour of the boron cluster is responsible for die observed degradation in the base pinched resistance. Moreover, it is possible to minimize these effects by a proper choice of ramp-down conditions.