Integration of NiSix based fully silicided (FUSI) metal gates with HfO2 high-k gate dielectrics offers promise for further scaling of complementary metal-oxide-semiconductor (CMOS) devices. A combination of High Resolution TEM (HRTEM) and small probe electron energy loss spectroscopy (EELS) and energy dispersive x-ray (EDX) analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSix film. Ni content varies near the NiSi/HfOx interface whereby both Ni-rich and monosilicide phases were observed. Spatially Non-uniform distribution of oxygen along NiSix/HfO2 interface was observed by dark field STEM imaging and EELS. Interfacial roughness of NiSix/HfOx was found higher than that of poly-Si/HfO2, likely due to compositional non-uniformity of NiSix. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.
By: M. A. Gribelyuk; C. Cabral Jr.; E. P. Gusev; V. Narayanan
Published in: RC23794 in 2005
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