Effects of geometric parameters and wettability on pattern collapse in nanoscale systems

Pattern collapse during the drying process following wet cleaning in semiconductor manufacturing has emerged as a critical challenge, significantly impacting chip yield and device reliability. To better understand the nanoscale collapse mechanisms, we performed molecular dynamics simulations on isolated, parallel double cantilever nanopillars with varying high aspect ratios (ARs)-representative nanostructures in semiconductor processes. The results reveal that at the nanoscale, pattern collapse is driven by a complex interplay of Laplace pressure, surface tension, and interatomic interactions. For nanopillars with relatively low ARs, deflection remains minimal. However, near the critical AR, the restoring force sharply diminishes, causing a pronounced deflection surge and eventual pattern collapse. Wettability strongly affects drying dynamics, leading to two distinct modes. Under weak wettability, drying proceeds top-down. In contrast, strong wettability induces inside-out drying. Due to the significant influence of interatomic interactions at the nanoscale, the critical AR obtained from molecular dynamics simulations for different contact angles is slightly smaller than the theoretical predictions. Overall, this study reveals the drying mechanisms and the final collapse configurations at the microscopic scale, while providing a useful supplement to theoretical models in predicting the critical aspect ratio, thereby offering guidance for the design of micro/nano devices and their drying processes.