BEHAVIOR OF ACTIVE AND INACTIVE BORON IN SI PRODUCED BY VAPOR-PHASE DOPING DURING SUBSEQUENT HYDROGEN ANNEALING

The behavior of active and inactive boron produced by vapor-phase dopi ng during subsequent hydrogen annealing is investigated. In samples do ped at 800 degrees C, there is a great deal of inactive boron at the s urface, which gives an exponential profile just after doping. For thes e samples, fast out-diffusion of inactive boron is observed during sub sequent hydrogen annealing at 800 degrees C. After 20 min of subsequen t annealing, almost all of the inactive boron diffuses out and the she et boron concentration becomes identical to the carrier concentration. The out-diffusion of inactive boron does not follow a Gaussian distri bution. In samples doped at 900 degrees C, almost complete activation is achieved just after doping. The diffusion of active boron during su bsequent annealing can be described as Gaussian: the surface carrier c oncentration decreases in proportion to the square root of the anneali ng time. This behavior is not affected by the existence of inactive bo ron.