Title: Impact of stress induced by stressors on hot carrier reliability of strained nMOSFETs

Authors: K.C. Lin; M.J. Twu; P.C. Juan; H.W. Hsu; H.S. Huang; M.C. Wang; C.H. Liu

Addresses: Department of Electronic Engineering, Ming Chuan University, Taoyuan 33348, Taiwan ' Department of Mechatronic Technology, National Taiwan Normal University, Taipei 10610, Taiwan ' Department of Materials Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan ' Institute of Mechatronic Engineering, National Taipei University of Technology, Taipei 10608, Taiwan ' Institute of Mechatronic Engineering, National Taipei University of Technology, Taipei 10608, Taiwan ' Department of Electronic Engineering, Minghsin University of Science and Technology, Hsinchu 30401, Taiwan ' Department of Mechatronic Technology, National Taiwan Normal University, Taipei 10610, Taiwan

Abstract: In this study, the nMOSFETs with contact-etch-stop-layer (CESL) stressor and SiGe channel have been fabricated with a modified 90 nm technology. The performance of nMOSFETs has been measured. And the hot carrier reliability of the SiGe-channeled nMOSFETs with various CESL nitride layers has also been extensively studied. In addition, the impact of stress induced by CESL stressor and SiGe-channel on hot-carrier reliability of the strained nMOSFETs has been analysed through experimental investigation. The shift in threshold voltage (ΔV_th) vs. stress time (t) under different stress temperatures was measured. Furthermore, according to the reliability results, both the interface states (N_it) and oxide trapped charges (N_ot) increased after hot-carrier stress. With regard to the hot-carrier reliability, for all stress conditions the degradation of strained nMOSFETs with compressive CESL stressor is more serious than the degradation of those with tensile CESL stressors. The nMOSFET devices with tensile CESL have better performance and hot-carrier reliability than those with compressive CESL. Moreover, it is suggested that the CESL-induced damages (N_it) located at the interface between gate dielectric and underlying channel be responsible for the hot-carrier reliability.

Keywords: CESL stressor; contact etch stop layer; SiGe channel; silicon germanium; hot carrier reliability; nanoelectronics; nanotechnology; strained nMOSFETs; hot carrier stress.

DOI: 10.1504/IJNT.2014.059807

International Journal of Nanotechnology, 2014 Vol.11 No.1/2/3/4, pp.27 - 39

Published online: 15 Nov 2014 *

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