Radiation-induced trapped charge in metal-nitride-oxide-semiconductor structure

Abstract

The radiation-induced trapped charge in the insulation layer of metal-nitride-oxide-semiconductor (MNOS) structure has been investigated. The mechanism of charge trapping under irradiation is studied by the radiation-induced mid-gap voltage shift using a simple charge trap model. The depth profile of fixed charge in the insulator before irradiation was evaluated by the mid-gap voltage of MNOS structures with varying insulator thicknesses using slanted etching. The irradiation tests were carried out using a Co-60 gamma ray source up to 1 Mrad(Si) with a gate voltage of +6 or -6 V. The calculated results using the model can be fitted well to the experimental results, and we confirmed the model is very useful to discuss the radiation-induced trapped charge. By simulating the mid-gap voltage shift of MNOS structures, we considered the possibility of a radiation hardened device.