Comprehensive Study of Contact Length Scaling Down to 12 nm With Monolayer MoS <sub>2</sub> Channel Transistors
Wen-Chia Wu, Terry Y.T. Hung, D. Mahaveer Sathaiya, Goutham Arutchelvan, Chen-Feng Hsu, Sheng‐Kai Su, Ang Sheng Chou, Edward Chen, Yun-Yang Shen, San Lin Liew, Vincent Hou, T. Y. Lee, Jin Cai, Chung-Cheng Wu, Jeff Wu, H.‐S. Philip Wong, Chao-Ching Cheng, Wen‐Hao Chang, Iuliana Radu, Chao-Hsin Chien
Abstract
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 300 \Omega \cdot \mu \text{m}$ </tex-math></inline-formula> at an extreme contact length of 12 nm at carrier concentration around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{13}}\mathrm {cm}^{-{2}}$ </tex-math></inline-formula> (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.