Swift heavy-ion induced trap generation and mixing at Si/SiO2 interface in depletion n-MOS

Large channel depletion n-channel MOSFET (Metal oxide semiconductor field effect transistor) is a basic Si-SiO2 structure to understand irradiation-induced modifications. The contribution of interface and oxide states denoted as Delta N-IT and Delta N-OT, respectively, was separated out by using I-D-V-DS, I-D-V-GS measurements. The threshold voltage shift Delta V-T (VT-irrad - VT-virgin) increased for all ions (50 MeV Li, B, F, P and Ni) over the fluence of 2 x 10(11)-2 x 10(13) ions/cm(2). The increase in Delta N-IT was associated to trap generation at Si-SiO2 interface, but a small change in Delta N-OT indicate less charge trapping in oxide. The electronic energy loss S, induced increase in Delta N-IT is not adequate to explain the large shift in threshold voltage. A rough estimate shows that the channel width, W should decrease by 40% for a large increase in Delta N-IT. Thus, the possible factor affecting reduction of W may be ion beam mixing induced broadening of Si-SiO2 interface. (c) 2005 Elsevier B.V. All rights reserved.