Modeling and Optimization of 3-D Bandgap-Engineered NAND Flash for Program Operation by Multilayer Tunneling With Trap Physics of Tunneling Nitride

A physics-based program model for bandgap-engineered (BE) 3-Dnandflash memory is presented, where multilayer tunneling (MLT) serves as the principal programming mechanism. The model derives effective tunneling fields across tunneling oxide (O1) and nitride (N1) in realistic 3-D structures, enabling precise calculation of MLT current and program transients. Bulk N1 trap states, represented by trap densities extracted from various measurements, are incorporated to evaluate their effects on programming efficiency and threshold voltage ($\text {V}_{\text {T}}$) shifts. Model predictions are validated through experimental results under various program bias conditions, with technology computer-aided design (TCAD) simulations conducted for different N1 trap densities and device geometries. Incremental step pulse programming (ISPP) results, including slope behavior, are analyzed to investigate the influence of N1 traps on programming efficiency. The model further enables optimization of O1 thickness, providing design guidance and physical insight for 3-D BEnanddevice programming.