Modeling and analysis of grain-orientation effects in emerging metal-gate devices and implications for SRAM reliability

This work introduces an analytical approach to model the random threshold voltage (V_th) fluctuations in emerging high-k/metal-gate devices caused by the dependency of metal work-function (WF) on its grain orientations. It is shown that such variations can be modeled by a multi-nomial distribution where the key parameters of its probability distribution function (pdf) can be calculated in terms of the physical dimensions of the devices and properties of the materials. It is highlighted for the first time that such variations can have significant implications for the performance and reliability of minimum sized circuits such as SRAM cells.