For gate oxides thinner than 40Å, conventional schemes of incorporating N in the oxides might become insufficient in stopping B penetration. By implanting N into the Si substrates with a sacrificial oxide layer, we have grown 25Å gate oxide and prevented B penetration in the presence of F after 90 min of 850 C and 10 s of 1050 C anneals. SIMS analyses surprisingly reveal a N peak formed within the thin oxide layer, while no N is left in the Si substrate beyond the oxide layer. In addition, no B is seen in the substrate, either. As a consequence, threshold voltage of pMOSFET's is shifted to a more negative value which agrees with calculations assuming no B penetration. Meanwhile, threshold voltage of nMOSFET's is not affected by the N implant, which confirms that B penetration is the only explanation for the pMOSFET data. Prevention of B peneitration also improves the short-channel effects for 0.25-m pMOSFET's, while no difference is seen in nMOSFET's with and without N implant.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.