Impact of Nitrogen Incorporation on Low-Frequency Noise of Polycrystalline Silicon/TiN/HfO2/SiO2 Gate-Stack Metal–Oxide–Semiconductor Field-Effect Transistors

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The impact of nitrogen incorporation into HfO2/SiO2 gate dielectrics in the gate-stack fabrication process on the low-frequency noise of the drain current of polycrystalline silicon (poly-Si)/TiN (10 nm)/HfO2/SiO2 gate-stack metal–oxide–semiconductor field-effect transistors (MOSFETs) is studied, considering the scaling of an equivalent oxide thickness with the reduction in interfacial layer SiO2 thickness and the plasma nitriding of gate dielectrics. The nitriding combined with nitrogen plasma and nitrogen diffusion from a 10-nm-thick TiN layer increases the normalized noise power spectral density owing to carrier mobility fluctuation, and decreases the slope γ of the 1/fγ noise spectrum owing to the increase in the number of trapped carriers at the bulk trap site in the gate dielectric layer. The reduction in SiO2 thickness from 1.5 to 0.8 nm showed less impact on the mentioned phenomena with TiN. These results suggest that nitrogen incorporation into HfO2/SiO2 gate dielectrics in the device fabrication process for poly-Si/metal nitride/HfO2/SiO2 gate stacks requires careful attention to suppress the power density of low-frequency noise.