Experimental and Theoretical Studies on the Solidification of Cyclohexane on Silicon (Si) Substrate

The semiconductor industry continually seeks optimal methods to avoid nanostructure collapse during the drying process of semiconductor device manufacturing. Despite the effectiveness of sublimation drying, the phenomenon of solidification with nonuniform crystal morphology remains a challenge associated with nanostructure collapse. Therefore, successful implementation of sublimation drying necessitates high-resolution frameworks to predict the freezing behavior of sublimating chemicals at various stages. In this study, we developed a unified and versatile numerical framework to model the solidification process of sublimating agents on silicon (Si) substrates. The enthalpy method was employed to capture the liquid supercooling, equilibrium freezing, and solid subcooling stages, while a two-dimensional (2D) phase-field method was used to capture the crystal growth stage, coupled with a one-dimensional (1D) kinetics model. Classical nucleation theory (CNT) was also calibrated to calculate the nucleation time and temperature. Furthermore, a laboratory-scale experiment was designed to investigate the solidification process of cyclohexane on a bare Si substrate, accurately characterizing the temperature transition and crystal morphology. The developed numerical framework showed excellent agreement with the experimental data regarding the temperature profile and crystal morphology. The results suggested that nonuniform crystal morphology and stochastic nucleation can be delicately controlled by adjusting the cooling conditions of Si substrates, thus preventing the collapse of nanostructure patterns during the semiconductor device manufacturing process.