Polycrystalline-Silicon-MOSFET-Based Capacitorless DRAM With Grain Boundaries and Its Performances

Abstract

In this work, a capacitorless one-transistor dynamic random access memory (1T-DRAM) based on a polycrystalline silicon (poly-Si) metal–oxide–semiconductor field-effect transistor was designed and analyzed through a technology computer-aided design (TCAD) simulation. A poly-Si thin film was utilized within the device because of several advantages, including its low fabrication cost and the feasibility of its use in high-density three-dimensional (3D) memory arrays. An asymmetric dual-gate structure is proposed to perform the write “1” operation and achieve high retention characteristics. The proposed 1T-DRAM cell demonstrates a high sensing margin of $8.73~\mu \text{A} / \mu \text{m}$ and a high retention time of 704.4 ms compared to previously reported 1T-DRAMs, even at a high temperature. In addition, the effect of grain boundaries on the memory performance of the proposed device was investigated, and the results validated the excellent reliability of its retention characteristics even in the presence of grain boundaries (>64 ms at $T =358$ K).

Keywords

• Polycrystalline silicon
• one-transistor dynamic random access memory
• grain boundaries
• metal–oxide–semiconductor field-effect transistor
• one transistor dynamic random access memory
• dualgate