Modeling the temporal evolution and stability of thin evaporating films for wafer surface processing.

Area of Science:

• Materials Science
• Surface Science
• Computational Chemistry

Background:

• Understanding fluid-solid interactions is crucial for thin film applications.
• Lithium tantalate (LTO) is a material with diverse electronic and optical properties.
• Accurate modeling of water adsorption and evaporation on LTO is needed.

Purpose of the Study:

• To investigate the interaction of thin evaporating water films with LiTaO3 (LTO).
• To develop a method for calculating disjoining pressure parameters using ab initio DFT.
• To model the temporal evolution of water layers during evaporation and spin drying.

Main Methods:

• Ab initio density functional theory (DFT) for computing adsorption energies.
• Calculation of Gibbs free energy of adsorption for water on LTO.
• Integration of disjoining pressure (molecular and structural components) with film thickness.
• Fitting disjoining pressure integral to DFT-derived Gibbs free energy.
• Modeling temporal evolution using spin drying and evaporation models.
• Diffusion and mass balance for water vapor above the film.

Main Results:

• Adsorption energies and Gibbs free energy of adsorption for water on LTO were computed.
• A method to determine disjoining pressure parameters from ab initio calculations was established.
• Temporal evolution of water layers was modeled using established evaporation and spin drying techniques.
• An analytical approximation for thick films was derived, independent of substrate properties.

Conclusions:

• The study provides a robust method for parameterizing disjoining pressure models using DFT.
• The findings enhance the understanding of water-thin film interactions on LTO.
• The derived approximation simplifies modeling for specific initial water layer conditions.