Advantages of Fluorine Introduction in Boron Implanted Shallow p+/n-Junction Formation

Abstract

The advantages of fluorine introduction on fabrication of shallow p⁺/n-junctions have been demonstrated. This was done by implanting fluorine onto the boron implanted p⁺/n-junction area prior to annealing. By introducing optimized amounts of fluorine, (1) the boron redistribution after annealing is suppressed, (2) the concentration of activated boron becomes higher, and (3) the leakage current level of the p⁺/n-junction decreases. These behaviors may be due to interactions between fluorine and defects in the silicon substrate or at the SiO₂/Si interface.