Electron Trap Characteristics of Silicon Rich Silicon Nitride Thin Films

Abstract

Charge localization causes initial retention loss and memory window narrowing after write/erase cycling in a nonvolatile memory device using a metal–oxide–nitride–oxide–semiconductor (MONOS) structure. To overcome these problems, we propose the use of silicon-rich silicon nitride (SRN) thin film as a charge-trapping layer. It was found that most of the electrons injected from the substrate were trapped at the interface between the SRN film and the top oxide and the number of electrons captured by bulk traps of the nitride is negligible. When negative bias is applied to the gate electrode, the electrons trapped at the top interface move back to the bottom interface with SRN. The high effective mobility of the electrons is presumably due to donor-like traps at 0.8 eV below the conduction band bottom of SRN.