This work examines boron penetration from p(+) polysilicon through 50-70 Angstrom gate dielectrics following B or BF2 implantation. Gate oxides were grown in N2O/O-2 mixtures with average nitrogen contents varying from 0 to 1.4%. A series of capacitance-voltage measurements were used to determine the amount of boron penetration, and secondary ion mass spectroscopy measurements were carried out to measure the depth profiles of incorporated nitrogen and fluorine. In addition, to better understand the role of fluorine, experiments were carried out to investigate the redistribution of fluorine in the poly/SiO2/Si system.