Quasi-damascene metal gate/high- k CMOS using oxygenation through gate electrodes

Abstract

We present a novel metal gate/high- k complementary metal–oxide–semiconductor (CMOS) integration scheme with symmetric and low threshold voltage ( V th) for both n-channel (nMOSFET) and p-channel (pMOSFET) metal–oxide–semiconductor field-effect transistors. The workfunction of pMOSFET is modulated by oxygen in-diffusion (‘oxygenation’) through the titanium nitride metal gate without equivalent oxide thickness (EOT) degradation. A significant V th improvement by 420 mV and an aggressively scaled capacitance equivalent thickness under channel inversion ( T inv) of 1.3 nm is achieved for the pFET by using a replacement process in conjunction with optimized oxygenation process. Immunity of nMOSFET against oxygenation process is demonstrated.