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

We present a novel metal gate/high-k complementary metal-oxide-semiconductor (CMOS) integration scheme with symmetric and low threshold voltage (V"t"h) 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"t"h improvement by 420mV and an aggressively scaled capacitance equivalent thickness under channel inversion (T"i"n"v) of 1.3nm is achieved for the pFET by using a replacement process in conjunction with optimized oxygenation process. Immunity of nMOSFET against oxygenation process is demonstrated.