Comprehensive Study of Contact Length Scaling Down to 12 nm With Monolayer MoS2 Channel Transistors

The 2-D transition metal dichalcogenides (2-D TMDs) have emerged as a promising channel material for postsilicon applications for their ultrathin structure and excellent electrostatic control. However, achieving low contact resistance at scaled contact length remains a challenge. This article overcomes this challenge through optimized deposition of a semimetal/metal stack in monolayer MoS2 channel transistors and obtains a low contact resistance of \sim 300 \Omega \cdot \mu \text{m} at an extreme contact length of 12 nm at carrier concentration around 10^{{13}}\mathrm {cm}^{-{2}} (based on the best data from transmission line measurement extraction). Similar ON-currents are maintained across a range of contact lengths from 1000 to 12 nm. Our calibrated TCAD model also validates that the tunneling distance at the metal-TMD interface exhibits a strongest positive correlation to the contact resistance. Doping in contact is then proposed and simulated as a potential solution for achieving a target corner of contact resistance and contact length defined by the International Roadmap for Devices and Systems (IRDS) for 2037.