Analysis of 80-MeV Carbon and 80-MeV Nitrogen Ion Irradiation Effects on N-Channel MOSFETs

Abstract

N-channel depletion MOSFETs were irradiated with 80 MeV Carbon (C6+) and 80 MeV Nitrogen (N6+) ions in the dose range from 100 krad (Si) to 30 Mrad (Si). The electrical characteristics of MOSFET such as threshold voltage (Vth), density of interface trapped charges ( ${{\Delta }}\text{N}_{\mathrm{ it}}$ ), density of oxide trapped charges ( ${{\Delta }}\text{N}_{\mathrm{ ot}}$ ), transconductance (gm), mobility ( ${{\mu }}$ ), leakage current (IL) and drain saturation current (IDSat) were studied as a function of dose. A considerable increase in ${{\Delta }}\text{N}_{\mathrm{ it}}$ and ${{\Delta }}\text{N}_{ot}$ and decrease in $\text{V}_{\mathrm{ th,}}\text{g}_{\mathrm{ m}}$ , ${{\mu }}$ , and $\text{I}_{\mathrm{ D~Sat}}$ was observed after irradiation. The ${{\mu }}$ was correlated with ${{\Delta }}\text{N}_{\mathrm{ it}}$ and it is found that the contribution of ${{\Delta }}\text{N}_{\mathrm{ ot}}$ in degrading the mobility of charge carriers is negligible.The ion irradiated results were compared with Co-60 gamma irradiated results and found that the degradation is more for Co-60 gamma irradiated devices at lower doses, whereas at higher doses, the degradation is more for heavy ion irradiated devices.