The Path to Climate-neutral Semiconductor Manufacturing:
Achieving 100% Destruction and Removal Efficiency (DRE) for CF₄ Emissions
The CF₄ Challenge
Tetrafluoromethane (CF₄) is one of the biggest challenges to climate protection facing the semiconductor industry. Effective destruction of CF₄ is therefore crucial for environmental and climate protection. Efficient treatment is also a key ESG goal for many companies. DAS EE offers effective solutions to help companies achieve these goals.
CF₄ is one of the most damaging industrial gases for the climate, as it has a very high global warming potential (GWP) of around 7,380 over a 100-year reference period, and it remains present in the atmosphere for at least 50,000 years, making it extremely long-lived. Therefore, even small emissions have a major impact over many millennia and contribute significantly to global warming. The global warming potential (GWP) of a greenhouse gas is a measure of how much it contributes to the warming of the Earth’s atmosphere compared to carbon dioxide (CO₂). This is typically considered over a period of 100 years.
The gas itself does not pose an acute health risk to humans. At normal concentrations, it does not irritate or poison the respiratory tract and is non-flammable. However, the real danger of CF₄ lies in its impact on the climate and the fact that it remains in the atmosphere for a significant length of time (‘climatic immortality’).
Example calculation: If one kilogram of CF₄ has a GWP₁₀₀ of 7,380, it will have the same effect in 100 years as 7,380 kilograms of CO₂.
Global Regulation of CF₄ Emissions in the Semiconductor Industry
Semiconductor manufacturing is a relevant source of CF₄ (tetrafluoromethane) emissions, which arise primarily from plasma etching and chamber cleaning processes. CF₄ is a fluorinated greenhouse gas with an extremely high global warming potential and is therefore subject to increasing regulatory scrutiny. However, CF₄ emissions are generally not regulated through CO₂ pricing mechanisms such as carbon taxes or emissions trading schemes. Instead, they are addressed through specific regulations on fluorinated greenhouse gases, mandatory reporting under national greenhouse gas inventories, and industry-specific reduction commitments (e.g. abatement requirements, best available techniques, or voluntary agreements).
In the European Union, CF₄ falls under the scope of the F‑Gas Regulation, which focuses on monitoring, reporting and the reduction of emissions of fluorinated greenhouse gases, including process gases used in semiconductor manufacturing, rather than direct carbon pricing.
In the United States, CF₄ emissions from semiconductor fabs are covered by mandatory reporting under the EPA Greenhouse Gas Reporting Program, complemented by long-standing voluntary reduction agreements between the industry and regulators.
In Taiwan, a key global hub for semiconductor manufacturing, CF₄ emissions are addressed through national greenhouse gas reporting requirements and sector-specific mitigation measures under the Climate Change Response Act, while CO₂ pricing instruments target energy-related emissions separately.
In Japan and South Korea, CF₄ and other fluorinated process gases are similarly regulated through reporting obligations, technology standards and industry guidelines, with a strong emphasis on abatement technologies.
Why is 100% Destruction and Removal Efficiency (DRE) Important in Semiconductor Manufacturing?
CF4 is primarily used in semiconductor manufacturing for plasma etching and plasma cleaning processes. Immediately after applying and exposing the photoresist to the wafer during photolithography, all areas of the wafer surface not protected by the photoresist are removed by plasma etching. Plasma cleaning is used at several points within the manufacturing process, e.g. as pre-cleaning before coating processes or after etching processes to prevent possible contamination from etching residues. CF4 is also used in the so-called dry cleaning of process chambers (chamber cleaning) in clean room manufacturing facilities to remove reaction products. Conventional thermal waste gas treatment systems achieve up to 95% DRE, but this is not enough in view of the aforementioned increasing regulatory pressure – next-generation chip fabs are striving for zero-emission subfabs.
The Technical Challenges
The destruction of CF₄ in the waste gas streams of semiconductor manufacturing requires the solution of two core problems: the extreme bond stability and the tendency of incompletely split CF₄ molecules (radicals) to recombine into CF₄. At 486 kJ/mol, the C–F bond in CF₄ is one of the strongest bonds in chemistry. It can therefore only be cleaved under extreme conditions, such as at temperatures above 1000 °C or in high-energy plasmas. At lower temperatures, there is a risk that the bonds will only be incompletely cleaved and that these radicals (fragments) will recombine to form new CF₄. Without countermeasures, the DRE can be practically zero.
Innovative Solutions for Highly Effective CF₄ Waste Gas Treatment
DAS Environmental Experts offers two technologically different but complementary processes for the near-complete destruction of highly stable process gases such as CF₄: Plasma-Wet and Burn-Wet. Both approaches pursue the same goal – a destruction and removal efficiency of over 99.9% – but use different physical-chemical mechanisms and thus meet different ecological and strategic requirements of the semiconductor industry.
Plasma-Wet: Future-proof Technology for Emission-free Manufacturing
Plasma-wet technology is based on the generation of a high-energy plasma state characterised by temperatures of around 10,000 Kelvin and high-energy electrons and ions. This plasma is generated by an electric arc between two electrodes and transferred to a flowing carrier gas, typically nitrogen. In this environment, the extremely stable CF₄ molecules are thermally broken down and converted into reactive fragments.
Through the controlled addition of oxygen and hydrogen (in the form of water), these fragments are completely converted into CO₂ and hydrofluoric acid (HF); the HF is then washed out and neutralised. The combination of high temperature, plasma activity and targeted oxidation prevents reactions back to undesirable starting compounds and enables high degrees of destruction.
STYRAX plasma wet systems already impress with DRE values well above 95%, low energy consumption and a small carbon footprint. As they do not require natural gas, they are considered particularly future-proof – a decisive advantage in view of global net-zero strategies and the increasing demand for a completely renewable energy supply in chip manufacturing. Ongoing research projects and collaborations with universities are actively driving further development towards an efficiency of >99.9%.
Burn-Wet: Maximum Efficiency for Highest Destruction Rates
The burn-wet process relies on the thermal oxidation of process gases in a burner-based system. The TILIA burn-wet system from DAS Environmental Experts has been independently validated and already achieves a destruction and removal efficiency of over 99.9% for CF₄ and other fluorinated greenhouse gases – significantly exceeding the target values of >95% and >99% DRE recommended in the SEMI SCC white paper (2024).
Both systems are extremely reliable and are particularly suitable for applications where maximum waste gas treatment performance is required regardless of process fluctuations.
Conclusion: The Path to Zero-emission Subfab is Achievable
Both plasma-wet and burn-wet technologies provide an effective foundation for significantly reducing fluorinated greenhouse gases in semiconductor manufacturing. While burn-wet systems such as TILIA already achieve destruction and removal efficiencies (DRE) close to 100%, plasma-wet opens up a sustainable path that supports the industry’s net-zero strategies by operating without fossil fuels. Both approaches thus form a powerful portfolio that covers both high technical effectiveness and environmental compatibility.
To completely eliminate the remaining residual emissions of highly stable molecules such as CF₄, DAS Environmental Experts is developing a catalytic process that achieves the last few percentage points of CF₄ decomposition at around 720 °C. Integrated into a multi-stage overall system – consisting of point-of-use exhaust gas treatment, central catalytic post-cleaning and downstream wet scrubbers – the result is an energy-optimised, resource-saving abatement concept. Water recycling and the minimisation of the carbon footprint make a particular contribution to sustainability.
This technology-based approach shows that zero CF4 emissions can already be considered an achievable process level today with the use of modern abatement technologies. By combining plasma technology, thermal catalysis and intelligent process control, even extremely climate-active F‑gases can be completely destroyed. At the same time, the drastic reduction in F‑gas emissions reduces future carbon tax burdens and strengthens manufacturers’ regulatory resilience.
DAS Environmental Experts thus offers not only individual solutions, but a holistic emissions strategy – from the optimisation of existing plants to the integration of renewable energies. The zero-emission subfab thus becomes a key component of climate-neutral semiconductor production and prepares manufacturers for the requirements of a sustainable industrial transformation.
“Whoever successfully treats CF4, successfully treats all other process gases. In the semiconductor industry, sustainability begins with the destruction of the most stable chemical compounds in waste gas treatment, which is made possible by our technologies and solutions.”
Dr. Guy Davies, CBDO, DAS Environmental Experts
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Director Sales Global