Annealing behavior of implanted BF2 in buried channel PMOS

Abstract

As devices are scaled down to sub-100 nm size, additional implant parameters such as instantaneous dose rate and wafer temperature as well as dose, energy, and implant angle have become increasingly important for controlling dopant profiles. The peak height of the concentration profiles for both boron and fluorine in BF2 implanted silicon, corresponding to the location of the amorphous/crystalline (a/c) interface, was observed to increase with increasing wafer temperature and to a lesser degree with increasing instantaneous dose rate. By increasing the wafer temperature, the threshold voltage (V-t) decreased dramatically while the sheet resistance (R-s) of the active area remained constant. The high peak height resulted in enhanced lateral diffusion, shorter effective channel length, and a lower threshold voltage in a buried channel p-type metal-oxide-semiconductor (PMOS).