CONTROL OF IMPLANT-DAMAGE-ENHANCED BORON-DIFFUSION IN EPITAXIALLY GROWN N-SI P-SI1-XGEX/N-SI HETEROJUNCTION BIPOLAR-TRANSISTORS/

Boron out-diffusion in epitaxially grown n-Si/p(+)-Si1-xGex/n-Si heter ojunction bipolar transistors is significantly enhanced during 850 deg rees C, 10 s rapid thermal annealing following arsenic emitter contact implantation. In this paper, we introduce three techniques which dram atically reduce boron out-diffusion during implant activation. Limitin g the post-implant processing to 600 degrees C for 2 min results in mi nimal diffusion giving acceptable device performance. A second techniq ue involves pulsed laser annealing of the As implant, which removes re sidual defects and eliminates enhanced diffusion during subsequent the rmal processing. Finally, we show that high bulk concentrations of oxy gen in the Si1-xGex (similar to 10(20) cm(-3)) dramatically reduce the implant-damage-enhanced boron diffusion. In addition to the depth pro files, electrical measurements performed on heterojunction bipolar tra nsistors, incorporating these fabrication techniques, show ideal colle ctor current characteristics and confirm the absence of deleterious bo ron out-diffusion effects.