DOPANT INTERACTIONS DURING THE DIFFUSION OF ARSENIC AND BORON IN OPPOSITE DIRECTIONS IN POLYCRYSTALLINE MONOCRYSTALLINE SILICON STRUCTURES

Experimental results of the effects of the arsenic doping concentratio n on the boron outdiffusion in n-polycrystalline/p-monocrystalline sil icon structures are presented. The boron diffusivity is only 30 times larger ii polycrystalline silicon than in monocrystalline silicon if t he arsenic doping is high enough to cause enhanced grain growth. The d iffusivity increase is about 130 if the polycrystalline silicon has sm all grains due to low arsenic doping. The boron loss from the base reg ion of an advanced bipolar transistor doping profile by outdiffusion i nto the emitter polycrystalline silicon is of the order of 20% and nee ds to be considered for accurate device modeling. (C) 1995 American In stitute of Physics.