Novel Double-Gate 1T-DRAM Cell Using Nonvolatile Memory Functionality for High-Performance and Highly Scalable Embedded DRAMs

摘要

We proposed for the first time a new double-gate 1T-DRAM cell to be applicable to sub-80-nm DRAM technology that has a silicon-oxide–nitride-oxide–silicon type storage node on the back gate (control gate) for nonvolatile memory (NVM) functionality. An NVM functionality is achieved by Fowler–Nordheim tunneling of electrons into the nitride storage node. Then, holes are accumulated on the back-channel, which makes 1T-DRAM operation in fully depleted silicon-on-insulator (SOI) MOSFETs possible and enhances retention characteristics. We investigated the effect of the NVM functionality on 1T-DRAM performance in nanoscale 1T-DRAM cells through device simulation and verified the effect in 0.6-$muhbox{m}$ devices fabricated on SOI wafers.