Modeling solid source boron diffusion for advanced transistor applications

In this paper, experimental results for B indiffusion from borosilicate glass (BSG) for formation of extremely shallow, highly doped regions are presented. The effects of BSG film concentration, anneal temperature and anneal time are presented. It is shown, for the first time, that the presence of excess silicon interstitials in the silicon substrate can strongly retard B indiffusion. In addition, the B indiffusion process from BSG is seen to enhance B diffusivity. These effects are modeled using B/Si interstitial interactions. This doping technique is integrated into a 0.15 /spl mu/m gate, 1.8 V CMOS process for PMOS source and drain extension (SDE) formation resulting in drive currents of 0.35 mA//spl mu/m at an off current of 1 nA//spl mu/m.