What is it about?
The issue of pattern collapse in device fabrication is one of the most important challenges facing integrated circuit manufacturers. While it is generally assumed that device scaling has exacerbated this problem due to the increasing device aspect-ratios, the many other factors that influence this complex dynamic phenomenon are not well understood. In a macroscopic scale, the two key forces involved in the bending of the solid structures are the Laplace pressure, due to the formation of the liquid meniscus; and the elastic restoring force of the solid material. It is common to analyze this problem with a static beam bending model, namely, a completely formed meniscus bridging across the device features and pulling them toward each other. In this paper, the importance of the transition from the planar to the curved air/liquid interfaces during drying is illustrated by a dynamic drying model. It is shown that in the presence of even partially formed menisci, the system of solid structures with bridging menisci is inherently unstable in a mechanical sense. By optical video imaging of the drying process in micron-sized features, the phenomenon of pattern collapse was observed in real-time. Interestingly and unexpectedly, the liquid menisci are observed to reconfigure themselves geometrically along the length of the structure. This results in the drying front moving laterally across the length of the structure rather than the conventionally expected top-to-bottom drying. To the best of the authors’ knowledge, this type of drying behavior has never been published before. The meniscus reconfiguration appeared to place an upper limit on the Laplace pressure that the liquid film sustained in the given geometry and drying condition. The impact of this phenomenon on pattern collapse will be discussed in more detail in the full paper.
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Why is it important?
Pattern collapse is an important issue to resolve in advanced semiconductor manufacturing.
Perspectives
This paper discusses the behavior of liquid meniscus in confined structures leading to pattern collapse. We observed that the liquid column inside a narrow trench does not dry from top of the trench to its bottom as one may expect in a large container. The meniscus reconfigured geometrically and the drying proceeds laterally along the length of the trench. We also discussed the Physics that governs the bending of high aspect ratio beams and how meniscus reconfiguration puts a cap on the Laplace pressure experienced by the liquid column.
David Mui
Lam Research Corp
Read the Original
This page is a summary of: Factors Influencing Drying Induced Pattern Collapse, Solid State Phenomena, August 2018, Trans Tech Publications,
DOI: 10.4028/www.scientific.net/ssp.282.201.
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