Contact engineering is of critical importance for two-dimensional (2D) transition metal dichalcogenide (TMD)-based devices.However,there are only a few solutions to overcome this obstacle because of the complexity of the TMD-contact interface.In this work,we propose a novel method using a soft plasma treatment followed by the seamless deposition of a metal electrode to reduce the contact resistance of MoS2 field effect transistors (FETs).The treated FETs exhibit three times higher mobility than the control FETs without plasma treatment.The soft plasma treatment can remove the facial sulfur atoms and expose the middle Mo atoms so that they come into direct contact with the metal electrode,thus greatly improving the contact behavior.First-principles calculation is also performed to support the experimental results.Our potentially scalable strategy can be extended to the whole family of TMD based FETs to provide a possible route of device processsing technology for 2D device application.