Investigation of the Electrical Coupling Effect for Monolithic 3-Dimensional Nonvolatile Memory Consisting of a Feedback Field-Effect Transistor Using TCAD

Abstract

In this study, the electrical characteristics and electrical coupling effect for monolithic 3-dimensional nonvolatile memory consisting of a feedback field-effect transistor (M3D-NVM-FBFET) were investigated using technology computer-aided design. The M3D-NVM-FBFET consists of an N-type FBFET with an oxide–nitride–oxide layer and a metal–oxide–semiconductor FET (MOSFET) in the top and bottom tiers, respectively. For the memory simulation, the programming and erasing voltages were applied at 18 and −18 V for 1 μs, respectively. The memory window of the M3D-NVM-FBFET was 1.98 V. As the retention simulation was conducted for 10 years, the memory window decreased from 1.98 to 0.83 V. For the M3D-NVM-FBFET, the electrical coupling that occurs through an electrical signal in the bottom-tier transistor was investigated. As the thickness of the interlayer dielectric (TILD) decreases from 100 to 10 nm, the change in the VTH increases from 0.16 to 0.87 V and from 0.15 to 0.84 V after the programming and erasing operations, respectively. M3D-NVM-FBFET circuits with a thin TILD of 50 nm or less need to be designed considering electrical coupling.