Amorphous SiO₂ Surface Irregularities and their Influence on Liquid Molecule Adsorption by Molecular Dynamics Analysis

Abstract

As the semiconductor industry relentlessly reduces device sizes, efficient and precise cleaning processes have become increasingly critical to address challenges such as nanostructure stiction. Gaining insight into the molecular behavior of water and isopropyl alcohol (IPA) on silicon dioxide (SiO2) surfaces is essential for controlling semiconductor wet cleaning processes. This study investigated the interactions between these liquids and SiO2 surfaces. Using molecular dynamics (MD) simulations, we examined the adsorption behavior of water and IPA molecules on both amorphous and crystalline SiO2 (a-SiO2 and c-SiO2) surfaces. Our findings reveal a preferential adsorption of water molecules on a-SiO2 surfaces compared to c-SiO2. This preference can be ascribed to the irregularity of the a-SiO2 surface, which results in the presence of silanol groups that remain inaccessible to the liquid molecules. In contrast, the c-SiO2 surface exhibits a more uniform and accessible structure. This study not only imparts crucial insights into the molecular behavior of water and IPA on SiO2 surfaces but also provides valuable information for future enhancements and optimization of semiconductor wet surface preparation, cleaning, etching and drying.