This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Among the gases used in semiconductor manufacturing, tetrafluoromethane (CF₄) is a greenhouse gas more than 6,000 times as potent as carbon dioxide. A KAIST research team has developed a technology that removes this gas with high efficiency while extending the usable lifetime of the catalyst that helps break it down by harnessing the "power of disorder," in which mixing multiple metal atoms stabilizes the catalyst's structure.
A research team led by Professor Minkee Choi from the Department of Chemical and Biomolecular Engineering, working in collaboration with researchers from Samsung Electronics, has developed a new catalyst capable of efficiently removing CF₄, a greenhouse gas used in processes such as the fabrication of fine semiconductor circuits, over long periods of use. The findings were published in June in the international chemistry journal Angewandte Chemie International Edition. CF₄ is used in processes such as dry etching, in which unwanted portions of a semiconductor wafer are selectively removed to create fine circuit patterns.
The problem lies in the CF₄ left over after use. Because its carbon and fluorine atoms are bound together extremely tightly, the gas does not easily decompose, and once released into the atmosphere, it can persist for roughly 50,000 years. Its impact on global warming is also more than 6,000 times greater than that of carbon dioxide.
To prevent CF₄ from being released unchanged, semiconductor manufacturing sites currently decompose it at high temperatures using steam and a catalyst. A catalyst speeds up chemical reactions, much like those used to reduce pollutants in car exhaust. However, conventional catalysts have suffered from declining performance with use.
This is because hydrogen fluoride (HF), generated as CF₄ decomposes, combines with moisture to create a highly corrosive environment, causing the catalyst's fine particles to aggregate or its structure to change. When small catalyst particles clump together into larger masses, the surface area in contact with the CF₄ to be treated shrinks, and performance declines accordingly. The research team solved this problem, paradoxically, by harnessing the "power of disorder." Mixing multiple types of atoms creates a complex, disordered structure that resists phase changes and remains stable.
This process is called entropy stabilization. In simple terms, it is a principle in which evenly mixing multiple kinds of atoms makes it difficult for a catalyst to clump together or change into another structure. Using this principle, the research team evenly incorporated multiple metals—aluminum (Al), zinc (Zn), gallium (Ga), nickel (Ni) and cobalt (Co)—into a single aluminate crystal structure.
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