Charge retention of scaled SONOS nonvolatile memory devices at elevated temperatures

Abstract

The charge retention characteristics in scaled SONOS nonvolatile memory devices with an effective gate oxide thickness of 94 Å and a tunnel oxide of 15 Å are investigated in a temperature range from room temperature to 175°C. Electron charge decay rate is sensitive to the temperature, whereas hole charge decay rate remains essentially constant. Based on experimental observations and an amphoteric trap model for nitride traps, an analytical model for charge retention of the excess electron state is developed. Using this thermal activated electron retention model, the trap distribution in energy within the nitride film is extracted.