Cleaning process to remove impurities is one of the essential processes for the fabrication of semiconductor device, where cleaning of trenches with water, replacement with IPA (isopropyl-alcohol) and its removal are iteratively carried out, and this process is still required upon recent reduction of the line width under 10 nm. This size is already at the border of the continuum limit where the theories of fluid mechanics can be applied. Hence, the authors adopted molecular dynamics (MD) simulations to examine the liquid behavior, especially wetting behavior and solid-liquid friction at the nanoscale with respect to simple Lennard-Jones fluid, water, methanol as well as IPA as the liquids, whereas simple non-polar crystal and silica as the solids [1-8]. In these studies, we have shown that surprisingly the liquid behavior even around this continuum border was qualitatively not remarkably different from that expected from a macroscopic point of view. On the other hand, the physical properties of liquids in the so-called adsorption layers formed in the vicinity of the solid typically of a few molecular diameters, are different from those in bulk, and their effects should be extracted and properly connected to the macroscopic scale, e.g. as a boundary condition to predict the liquid behavior.
In the presentation, we will discuss about the MD simulation results of liquid infiltration into a nanoscale slit, effects of gas molecules in the slit as well the diffusion of water and alcohol molecules on OH-terminated silica surfaces. In addition, the replacement procedure of adsorbed water/alcohol by bulk alcohol/water liquid will be discussed.
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[2] D. Surblys, F. Leroy, Y. Yamaguchi, F. Mueller-Plathe, J. Chem. Phys. 148 (2018), 134707.
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[6] S. Nishida, D. Surblys, Y. Yamaguchi , K. Kuroda, M. Kagawa, T. Nakajima and H. Fujimura, J. Chem. Phys. 140 (2014), 074707.
[7] D. Surblys, Y. Yamaguchi , K. Kuroda, T. Nakajima and H. Fujimura, J. Chem. Phys. 140 (2014), 034505.
[8] Y. Yamaguchi, M. Kawakami, D. Yano, Jpn. J. Multiphase Flow 32-2 (2018), 218 (in Japanese).
