Optimization of Bias Schemes for Long-Term Endurable 1T-DRAM Through the Use of the Biristor Mode Operation

Abstract

The long-term endurance characteristics are investigated for MOSFET-based capacitorless one-transistor DRAM (1T-DRAM) under the conventional versus biristor mode. Based on the experimental results and on a supporting simulation study, it was found that the MOSFET-based 1T-DRAM, when enabled by a biristor mode, is preferred for long-term endurance compared with MOSFET-based 1T-DRAM when operated in a conventional mode. Although a high drain voltage is required in the biristor mode for programming, improved endurance characteristics are observed. The simulation study showed that this feature is achieved by the suppression of hot-hole-induced degradation, which arises from the absence of a gate use at the dynamic cell. Thus, this letter provides a new type of device architecture as well as a novel and innovative operational method pertaining to conventional 1T-DRAM to mitigate the problem of limited endurance.