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 ΔN IT and ΔN OT, respectively, was separated out by using I D-V DS, I D-V GS measurements. The threshold voltage shift ΔV T (V T-irrad - V T-virgin) increased for all ions (50 MeV Li, B, F, P and Ni) over the fluence of 2 x 1011-2 x 1013 ions/cm2. The increase in ΔN IT was associated to trap generation at Si-SiO2 interface, but a small change in ΔN OT indicate less charge trapping in oxide. The electronic energy loss S e induced increase in ΔN 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 ΔN IT. Thus, the possible factor affecting reduction of W may be ion beam mixing induced broadening of Si-SiO2 interface