Modeling study of capacitance characteristics in strained High-K Metal gate technology: impact of Si/SiO_2/HK interfacial layer and band structure model

摘要

The importance of developing predictive modeling tools has considerably increased with the diffusion of nanoscale technologies, in which strained layers and he-terojunctions determine the materials modeling complexity. A self-consistent Poisson-Schroedinger solver based on a full-band (FB) k.p method has been developed and validated on large test structures, studying the oxide capacitance for various gate stacks. Among the effects governing the electrostatics of the devices, the impact of band structure models of the oxide, of the semiconductor, and the effects of the Si/SiO_2 interfacial layers have been studied. The predictions of FB k.p models are compared a tight binding model and to simpler effective mass approximation (EMA) models. The oxides have been treated as pseudo zinc-blend materials, adjusting the model parameters using ab-initio simulations. The importance of having such accurately calibrated models relies in the reduced computational time of EMA models with respect to FB models. Additionally 2D TCAD simulations have been performed using a commercial simulation package to assess the predictions of these simpler models.