Channel Length Scaling Limit for LDMOS Field-Effect Transistors: Semi-classical and Quantum Analysis

We find a fundamental limit of channel-length scaling for Laterally Diffused Metal-Oxide-Semiconductor (LDMOS) FETs. We optimize a set of devices with different channel lengths, from 10 nm to 100 nm, through an optimization algorithm to meet a pre-determined criterion for drain-to-source subthreshold leakage-current and breakdown voltage. We identify an optimum channel length of 40 nm for both 5V and 3.3V planar LDMOS devices. To assess the possible importance of source-to-drain tunneling in short-channel LDMOS devices, we also perform a quantum mechanical study of 5 nm to 15 nm channel length LDMOS devices. We find that classical effects, rather than quantum tunneling, determine the scaling limit of LDMOS.