Design Optimization of Multigate Bulk MOSFETs

The design optimization of multigate bulk MOSFET structures is investigated for sub-20-nm gate lengths. Three-dimensional device simulations were used to optimize device design parameters such as the retrograde channel doping profile, as well as the length, width, and height of the gated channel region. Compared with the FinFET design, the results indicate that the tri-gate MOSFET design is promising for continued bulk-Si CMOS transistor scaling, because it can achieve similar on-state current performance and intrinsic delay [for the same channel stripe pitch (SP)] at a lower height/width aspect ratio (0.8 versus 2.17) and less aggressive retrograde channel doping gradient for improved manufacturability. Only by increasing the height of the channel region and/or reducing the channel SP can the FinFET bulk MOSFET design achieve better delay, but at the cost of reduced manufacturability.