Journal article
Orientation-dependent etching of silicon by fluorine molecules: A quantum chemistry computational study
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, v 41(5), 52602
Sep 2023
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Anisotropic etching is a widely used process in semiconductor manufacturing, in particular, for micro- and nanoscale texturing of silicon surfaces for black silicon production. The typical process of plasma-assisted etching uses energetic ions to remove materials in the vertical direction, creating anisotropic etch profiles. Plasmaless anisotropic etching, considered here, is a less common process that does not use ions and plasma. The anisotropy is caused by the unequal etching rates of different crystal planes; the etching process, thus, proceeds in a preferred direction. In this paper, we have performed quantum chemistry modeling of gas-surface reactions involved in the etching of silicon surfaces by molecular fluorine. The results confirm that orientation-dependent etch rates are the reason for anisotropy. The modeling of F-2 dissociative chemisorption on F-terminated silicon surfaces shows that Si-Si bond breaking is slow for the Si(111) surface, while it is fast for Si(100) and Si(110) surfaces. Both Si(100) and Si(110) surfaces incorporate a larger number of fluorine atoms resulting in Si-Si bonds having a larger amount of positive charge, which lowers the reaction barrier of F-2 dissociative chemisorption, yielding a higher etch rate for Si(100) and Si(110) surfaces compared to Si(111) surfaces. Molecular dynamics modeling of the same reactions has shown that the chosen reactive bond order potential does not accurately reproduce the lower reaction barriers for F-2 dissociative chemisorption on Si(100) and Si(100) surfaces. Thus, reparameterization is necessary to model the anisotropic etching process that occurs at lower temperatures.
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Details
- Title
- Orientation-dependent etching of silicon by fluorine molecules: A quantum chemistry computational study
- Publication Details
- JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, v 41(5), 52602
- Publisher
- A V S AMER INST PHYSICS; MELVILLE
- Grant note
- The research described in this paper was conducted under the Laboratory Directed Research and Development (LDRD) Program at Princeton Plasma Physics Laboratory, a national laboratory operated by Princeton University for the U.S. Department of Energy under Prime Contract No. DE-AC02-09CH11466. The United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Drexel University
- Web of Science ID
- WOS:001136502800002
- Scopus ID
- 2-s2.0-85169977417
- Other Identifier
- 991021861171804721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Materials Science, Coatings & Films
- Physics, Applied