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

Paper Number: 143402

143402 - Mechanical Property Evaluation of Sublimation Agents on Nanostructure Stability in Semiconductor 

In the realm of semiconductor device manufacturing, the ongoing trend towards miniaturization has introduced significant challenges, particularly during the drying phase of fabrication, where the collapse of nanostructures has emerged as a critical issue. This collapse is largely attributed to the surface tension forces applied by the residual liquid trapped within the nanostructures throughout the drying process. To counteract this problem, the method of sublimation drying has been proposed as an effective strategy. In this process, a sublimating agent is deposited on a silicon (Si) substrate to form a solid film by cooling and solidifying or precipitation. This is followed by the application of an inert gas spray, aimed at drying the substrate while ensuring the sublimating agent remains in a solid state.

Despite the adoption of sublimation drying, instances of nanostructure disintegration continue to be reported, suggesting that this issue is not fully resolved by current methodologies. This persistence of nanostructure collapse has been linked to the uneven properties of the film across the substrate, indicating a complex interplay of factors that contribute to the disintegration of nanostructures. A significant gap in current understanding is the exact relationship between the properties of the sublimator film on the substrate and the occurrence of pattern collapse, pointing to a need for further investigation into the conditions necessary to prevent such collapses.

The presented research aims to fill this gap by exploring the relationship between the collapse rate of nanostructures during sublimation drying and the mechanical properties of the sublimator thin films. Various mechanical properties such as Young's modulus, viscosity, flexibility, and rapture stress of thin films prepared by cooling and solidifying eight different sublimation agents were evaluated by indentation testing using a spherical indenter. Following this assessment, the pattern collapse rate of nanostructures on Si substrates treated with sublimation drying with cooled and solidified films of these different sublimation agents was examined. These findings reveal a notable correlation between the rate of viscosity change as the sublimation agent transitions from a liquid to a solid state and the pattern collapse rate of nanostructures, while no significant correlation is found with other mechanical properties. This underscores the vital role played by the rate of viscosity change in the collapse of nanostructures, suggesting that the stress induced during the agent's solidification process is a key factor in this phenomenon.

These findings not only develop a basis for selecting appropriate sublimation agents and optimizing solidification conditions to avert pattern collapse but also contribute to a broader understanding of the stress mechanisms involved during the solidification of sublimation agents on nanostructures, offering potential pathways for future research and technological advancements in semiconductor fabrication.

Presenting Author: Yosuke Hanawa SCREEN Holdings Co., Ltd.

Presenting Author Biography: Yosuke Hanawa is a semiconductor cleaning process researcher at SCREEN Holdings Corporation, where he is working on the development of drying techniques to suppress pattern collapse and the analysis of interfacial phenomena in the wet. He likes to commute by bicycle.

Authors:

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