Greenhouse gases from semiconductor processes, efficiently decomposed with high-durability catalyst

Dr. Ryi Shin-kun and his research team from the CCS Research Department at the Korea Institute of Energy Research (President Yi, Chang-Keun, hereinafter referred to as KIER) have succeeded in developing a new catalyst capable of stably decomposing greenhouse gases generated in semiconductor and display manufacturing processes, even at low temperatures.

Flagship industries of the Republic of Korea, semiconductors and displays, are expected to continue their growth as the importance of AI and virtual reality increases. However, during semiconductor and display production, gases such as carbon tetrafluoride (CF₄) and hexafluoroethane (C₂F₆), which have a greenhouse effect more than 5,000 times greater than carbon dioxide, are emitted, causing negative impacts on the environment.

To address this issue, the industry has been using technologies such as burners or plasma to eliminate greenhouse gases. However, combustion methods using burners have the drawback of generating carbon dioxide, while plasma methods require large amounts of electricity, limiting their applicability for large-scale processing.

In response, the United States and Japan have been actively researching catalytic decomposition methods since the 1990s that can handle large-scale breakdown without emitting carbon dioxide. However, the catalysts developed so far operate only at high temperatures above 750 °C, requiring significant amounts of energy, and have a short lifespan of less than 1,000 hours, creating the need for technologies that can overcome challenges in cost-effectiveness and durability.

To address these limitations, the research team optimized the catalyst composition and created a catalyst that remains effective for over 4,000 hours of continuous operation at lower temperatures than conventional catalysts.

Fluorinated gases such as carbon tetrafluoride are decomposed through hydrolysis reactions with water. For fluorinated gases to react quickly and extensively with water even at low temperatures, the catalyst must provide ample space for the gases to enter. This concept is called “Lewis acid sites,” and increasing the number of Lewis acid sites requires technology to optimize the zinc content within the catalyst.

The research team maximized the number of Lewis acid sites by adjusting the content of zinc, alumina, and phosphorus in the catalyst to optimal levels. The catalyst they developed stably decomposed more than 98% of high-concentration carbon tetrafluoride (over 5,000 ppm) even at 700 °C, which is 50 °C lower than the operating temperature of conventional catalysts. By lowering the operating temperature, energy efficiency increased by more than 10% compared to existing catalysts.

Testing of the developed catalyst showed that its performance did not deteriorate even after 4,000 hours of continuous operation at 5,000 ppm, demonstrating long-term durability. This represents more than twice the performance of the commercial standard, which is 1,000 hours of continuous operation at 2,000 ppm. In addition, the catalyst was confirmed to simultaneously decompose sulfur hexafluoride (SF₆) and nitrogen trifluoride (NF₃) simultaneously, which are emitted from semiconductor processes, as well as refrigerant gases such as pentafluoroethane, thereby broadening its potential applications.

The research team has also prepared a method for mass-producing the developed catalyst. By applying an extrusion process to catalyst production, they made it possible to adjust the shape and size of the catalyst depending on its application. In particular, the catalyst can be produced in a honeycomb structure, which offers a large reaction surface area and advantages in weight reduction, thereby enhancing its commercialization potential.*

Dr. Ryi Shin-kun, the lead researcher, stated, “The developed catalyst is a versatile catalyst capable of treating not only various fluorine-based compounds emitted from semiconductor and display processes, but also waste refrigerants. It can be applied not only to semiconductors and displays, but also to junkyards and discarded home appliances, and thus contribute greatly to achieving the national greenhouse gas reduction targets.”

Meanwhile, this research was carried out with support from KIER’s research program and the World Class Plus Program of the Ministry of Trade, Industry and Energy.