Session: 11-09-02: Phase-Change Processes: Fundamentals and Applications

Paper Number: 143552

143552 - Solidification of Cyclohexanol in Sublimation Drying for Enhancing Semiconductor Manufacturing: Experimental and Mathematical Studies 

Solidification, as one of the phase transitions, involves the freezing of a liquid when the temperature drops below its fusion point. It is an omnipresent phenomenon in nature and industry. Specifically, solidification is applied as an important part of the sublimation drying process of semiconductors to avoid nanostructure collapse, thus optimizing semiconductor device manufacturing. The current advancement of this topic in the literature has been extensive on the mechanical characteristics of sublimation drying while neglecting the effect of the non-uniformity of the crystal morphology during solidification. For crystal morphology, the literature is rife with the ice/water phase change, binary solution (e.g., sucrose and salt aqueous solutions), and binary alloys.

Despite great efforts, the solidification phenomenon with non-uniform crystal morphology plays a vital role in nanostructure collapse. Meanwhile, the solidification behavior of commonly used sublimation chemicals, such as cyclohexane and cyclohexanol, was not well understood. The optimization of freezing sublimation chemicals at multiple spatio-temporal scales on silicon substrate during sublimation drying is therefore of great interest in both fundamental and applied research.

In this study, a well-thermally controlled experimental chamber was designed and used for investigating the solidification behavior of cyclohexanol with both testing and observed samples. High-speed cameras, thermocouples, and advanced image analysis were employed to characterize the temperature transition, nucleation, crystal growth, and crystal morphology. Additionally, a multi-scale mathematical model was developed to capture the solidification behavior of cyclohexanol at macro-, meso-, and micro-scales. The model is a hybrid framework incorporating various analytical and numerical schemes, such as exact solutions using the separation of variables for macro-scale heat conditions without phase change, numerical enthalpy method for macro-scale phase change heat conduction, phase field modeling using the finite-difference method coupled with a simplified kinetics equation at meso-scale, and empirically expression for heterogeneous nucleation at micro-scale.

The comparisons were made between the experimental and simulated results regarding temperature profile, nucleation time and temperature, crystal growth rate, and crystal morphology at different cooling conditions for comprehensive validation. The results demonstrated a good agreement between the experimental and simulated data. Optimization for freezing cyclohexanol on silicon substrate was statistically conducted through the Monte-Carlo method. The optimized results suggested a specific cooling condition for cyclohexanol at a particular size of the silicon substrate for optimal performance of sublimation drying without any nanostructure collapse.

The presented framework involves experimental, mathematical, and optimization methods and provides a comprehensive guideline for analyzing the sublimation drying process for semiconductors from a thermal perspective. Furthermore, the framework also has the capacity to evaluate other sublimation chemicals and their optimized conditions.

Presenting Author: Minghan Xu McGill University

Presenting Author Biography: I am a Ph.D. Candidate in the Department of Mining and Materials Engineering at McGill University, specializing in the field of phase change heat transfer. My research employs physics-based modeling, sensitivity analysis, and experiments with the overarching goal of advancing our fundamental understanding of phase change phenomena, particularly for the freezing process. I apply my fundamental research to engineering applications (e.g., civil and mining), including but not limited to: phase change materials for thermal energy storage, artificial ground freezing for permafrost protection, and droplet and spray freezing for renewable heating and cooling.

I have working experience as a researcher at CanmetENERGY, a national laboratory under Natural Resources Canada, where I focused on CO2 ground source heat pump systems for space heating applications. I am a Vanier Scholar and a recipient of Fonds de recherche - Nature et technologies (FRQNT) Doctoral and Master's scholarships. I obtained my Bachelor of Engineering (First Class Honours) in Bioresource Engineering from McGill University.

Authors:

Minghan Xu McGill University
Mohammaderfan Mohit McGill University
Yosuke Hanawa SCREEN Holdings Co., Ltd
Jianliang Zhang SCREEN Holdings Co., Ltd
Junichi Yoshida SCREEN Holdings Co., Ltd.
Koichi Sawada SCREEN Holdings Co., Ltd.
Yuta Sasaki SCREEN Holdings Co., Ltd.
Atsushi Sakuma Kyoto Institute of Technology
Agus Sasmito McGill University