In this study, we employ TCAD (Technology Computer-Aided Design) simulations to comprehensively investigate the influence of process-induced variations on the electrical parameters of 3D NAND flash memory string. While prior research has extensively addressed dimensional variability, this work uniquely emphasizes the impact of material and transport level fluctuations, particularly focusing on oxide fixed charge (Qf), interface trap charge (Qtrap) and electron mobility (μn). Our simulations are designed to assess the variability in key electrical parameters, on-current (Ion), threshold voltage (Vth), maximum transconductance (Gm) and subthreshold swing (SS). Results indicate that Vth is significantly influenced by variations in Qf and Qtrap leading to a 36% change, while μn has a substantial impact on Ion and Gm with changes of 21% and 19%, respectively. These findings underscore the critical importance of process stability and variability-aware circuit design methodologies, particularly in the context of aggressively scaled, high-density vertical NAND architectures. As device integration continues to expand into the hundreds of layers, understanding and mitigating the impact of non-idealities such as charge fluctuation and mobility degradation becomes essential for maintaining reliability, yield, and overall system performance. Our results offer valuable insights for device engineers and memory architects aiming to enhance the robustness of next-generation 3D NAND technologies.