Multi-Bit Unified Memory Concept in FinFETs with ONO Buried Insulator

Abstract

Transient mechanisms in SOI FinFETs fabricated on ONO buried insulator were investigated for multi-bit unified memory operation. In nonvolatile memory applications, charges are trapped/detrapped in the nitride buried layer by back-gate or drain bias and are sensed at the front-channel. Volatile charges are generated by impact ionization and stored in the silicon body of the transistor. The volatile charges are sensed at the back-channel. Our experimental results demonstrate multi-bit unified memory by advantageously combining the two memory modes. Systematic measurements reveal that the impact of the nonvolatile charges located near the drain side on the volatile sensing margin is larger than the charges located at the opposite side.