Simulation of capacitorless dynamic random access memory based on junctionless FinFETs using grain boundary of polycrystalline silicon

In this paper, we report a junctionless FinFET-based capacitor less dynamic memory by using three-dimensional technology computer-aided design simulations. To realize the 1T-DRAM, the proposed device has been designed as a structure in which a poly-si layer is deposited on the fins of a typical junctionless FinFET. Poly-si has one or more grain boundaries (GB). A GB contains multiple traps, and these traps generally degrade device performance. Also, when poly-si is grown and utilized in semiconductor devices, non-uniform GB is formed across the entire wafer. Therefore, devices manufactured using poly-si have different GBs for each device and the performance of devices fabricated on the same wafer is different. Therefore, it is essential to design a device that can operate normally regardless of GB. The 1T-DRAM proposed in this study was simulated with the existence of GB and the direction of GB differently. Finally, a device that operates normal memory regardless of GB was designed. According to the simulation results, the retention time of the proposed 1T-DRAM has a margin of more than 10 uA/um and a retention time of more than 64 ms, regardless of the presence or absence of GBs.