4-Transistor Ternary Content Addressable Memory Cell Design using Stacked Hybrid IGZO/Si Transistors

In this paper, we propose a 4T-based paired orthogonally stacked transistors for random access memory (POST-RAM) cell structure and also suggest ternary content addressable memory (TCAM) applications. POST-RAM cells feature vertically stacked read and write transistors, maximizing area efficiency by utilizing only two transistors' space. POST-RAM employs InGaZnO (IGZO) channels for write transistors and single crystal silicon channels for read transistors, which results in both extremely long memory retention and fast reading performance. A comprehensive 3D-TCAD simulation is conducted to validate the procedural design of the proposed device structure. Furthermore, we introduced a self-clamped searching scheme (SC2S) designed to enhance the efficiency of TCAM operations. The results conclusively demonstrate that operating a TCAM based on the proposed POST-RAM architecture can lead to a 20% improvement in energy-delay product (EDP). Notably, the delay performance can be enhanced by up to 40% when compared to a 16T SRAM-based TCAM. Additionally, the proposed scheme enables a more than sixfold reduction in cell area, demonstrating an efficient use of space.