High-k gated metal-oxide-semiconductor field-effect-transistors (MOSFETs) with Cl-2 and CF4 plasma treatments are studied in this work. A higher-k HfON with more tetragonal phase is formed by the halogen plasma treatment on interfacial layer (IL). A low inversion equivalent oxide thickness in MOSFET is obtained with the Cl-2 plasma treated IL In addition, high mobility and transconductance, and low subthreshold swing are obtained by the Cl-2 plasma treatment, which therefore is a promising interface engineering for advanced MOSFETs. (C) 2014 Elsevier Ltd. All rights reserved.