Extending the life of N/O stack gate dielectric with gate electrode engineering

Nitride/oxynitride (N/O) stack gate dielectrics show significant leakage reduction and strong boron penetration resistance as compared to oxynitrides. The life of the N/O stack can be further extended by gate electrode engineering. With pre-doped poly-Si gates for both N- and P-MOS devices, poly-Si gate depletion can be minimized and inversion Tox can be reduced. Employment of NiSi can further reduce inversion Tox by minimizing gate dopant deactivation. In addition, a fully-silicided (FUSI) NiSi metal gate electrode totally eliminates poly-Si gate depletion and reduces the inversion Tox by 4-6A. Both FDSOI devices and strained Si devices with N/O stack and FUSI metal gate showed performance improvements and no degradation in gate dielectric reliability.