Soft Error in Saddle Fin-Based DRAM at Cryogenic Temperature

Abstract

This study examines the impact of soft error by heavy ions on saddle fin-based dynamic random access memory (DRAM). The investigation is conducted using technology computer-aided design (TCAD) simulation at different temperatures ranging from 77 to 300 K. At 300 K, charge sharing is greater compared to 77 K due to the increased prominence of the bipolar amplification effect. The decrease in storage node potential ( $V_{SN}$ ) caused by charge sharing varies by up to 1.31% between 77 and 300 K. Nevertheless, if the linear energy transfer (LET) of the ion is below 1 MeV $\cdot $ cm2/mg, temperature increase does not result in enhanced charge sharing. This is because there is an insufficient generation of electron-hole pairs (EHPs) to trigger a bipolar amplification effect. On the other hand, the amount collected charge is greater at 77 compared to 300 K because the mobility of the carriers increased as the temperature decreased. The variation in $V_{SN}$ due to the collected charge is as high as 13.19% between 77 and 300 K. When comparing the reduction in $V_{SN}$ caused by collected charge and charge sharing, it is seen that the influence of collected charge is more pronounced at 77 and 300 K. TCAD simulations are used to investigate strategies for mitigating the heavy ion effect. Enhancing the bit-line junction can reduce the impact of heavy ions on the saddle fin-based DRAM. As a result, several EHPs generated by heavy ions can be moved towards the junction of the bit-line.