Transient Analysis of Warm Electron Injection Programming of Double Gate SONOS Memories by means of Full Band Monte Carlo Simulation

TL;DR

This paper explores warm electron injection for programming double-gate SONOS memories using full band Monte Carlo simulations, demonstrating its viability for low-power, reliable, and localized charge storage with potential for multi-level operation.

Contribution

It introduces a time-dependent simulation approach combining continuum and Monte Carlo methods to analyze warm electron injection in SONOS memories, highlighting its advantages over traditional methods.

Findings

Warm electron injection enables low-voltage programming.

It offers localized charge trapping suitable for multi-level storage.

The method reduces power consumption and enhances device reliability.

Abstract

In this paper we investigate "Warm Electron Injection" as a mechanism for NOR programming of double-gate SONOS memories through 2D full band Monte Carlo simulations. Warm electron injection is characterized by an applied VDS smaller than 3.15 V, so that electrons cannot easily accumulate a kinetic energy larger than the height of the Si/SiO2 barrier. We perform a time-dependent simulation of the program operation where the local gate current density is computed with a continuum-based method and is adiabatically separated from the 2D full Monte Carlo simulation used for obtaining the electron distribution in the phase space. In this way we are able to compute the time evolution of the charge stored in the nitride and of the threshold voltages corresponding to forward and reverse bias. We show that warm electron injection is a viable option for NOR programming in order to reduce power supply, preserve reliability and CMOS logic level compatibility. In addition, it provides a well localized charge, offering interesting perspectives for multi-level and dual bit operation, even in devices with negligible short channel effects.