3D Simulation Study of Work-Function Variability in a 25 nm Metal-Gate FinFET with Curved Geometry using Voronoi Grains

A full-scale 3D simulation study of the impact of metal gate granularity (MGG) on the off-state of a 25 nm length gate SOI FinFET is carried out. The 3D simulations are performed using a parallel finite-element simulator within the drift-diffusion approximation using density gradient quantum corrections. The shapes in the device are described by using splines, and metal grains are modelled using Voronoi diagrams. We study two different grain sizes and silicon fin corner geometries. While the impact of the geometry is found to be negligible in our simulations due to a relatively large size of the device, the grain size has a large impact on the variability of subthreshold characteristics.