Edwards Responds To UN Greenhouse Gas Guidelines
More stringent IPCC guidelines include accounting for CF4 by-product formation and emissions.
The Intergovernmental Panel on Climate Change (IPCC), the United Nations' body for assessing the science related to climate change, has just released the latest refinement to its 2006 Guidelines. As part of an effort to tackle climate change, the refined regulations tighten control on new greenhouse gases used in semiconductor manufacturing and increase requirements for reporting and accountability for manufacturers.
“The IPCC has recognised that there is a gap between the amount of greenhouse gas measured in the atmosphere and the amount calculated from the inventory of known sources of emission,” said Mike Czerniak, visiting industrial professor, Bristol University, and environmental solutions business development manager, Edwards. “The gap is of particular concern for gases such as perfluoro compounds (PFCs), which not only have extraordinarily high global warming potentials (GWP) but also extremely long lifetimes in the atmosphere, as long as 50,000 years.”
Two new mechanisms for PFC formation during semiconductor manufacturing have been identified and emission factors have been added to the latest IPCC refinement:
- CF4 formation when cleaning chemical vapor deposition (CVD) chamber deposits.
- CF4 formation by reaction of fluorine with hydrocarbon fuel in combustion-based abatement in systems that mix the fuel and process chamber effluent.
“For the first time ever, there is a new emission factor for combustion-based abatement of fluorine - direct accountability is now required, in the form of a data-backed certification from the equipment manufacturer that the reaction is minimised,” said Czerniak. “PFC formation can be minimised by appropriate combustor design.”
Edwards' inward-fired combustor avoids the mixing of chamber exhaust and fuel that, in other designs, can lead to the production of PFCs where they did not exist in the original exhaust stream. The lower, more uniform temperature profile of the inward-fired combustor ensures a high destruction removal efficiency (DRE), with low NOx generation. Inward-fired combustors have been standard on Edwards' abatement systems since the company started developing them in the 1990s.