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Reducing PFC emissions

IBM releases some perfluorocompounds (PFCs) from its semiconductor manufacturing operations. Although the releases are in relatively small amounts (in carbon dioxide equivalents, when compared to the company's indirect CO2 emissions), IBM was the first semiconductor manufacturer to set a numeric reduction target for PFCs in 1998.

We subsequently set a second generation goal to achieve an absolute reduction in PFC emissions from semiconductor manufacturing of 25 percent by 2010 against a base year of 1995. We exceeded this goal by reducing IBM's PFC emissions by 36.5 percent at year-end 2010.

IBM is presently evaluating a third generation goal for PFC emissions reduction. A separate but relevant activity is the Semiconductor Industry Association's current work with the United States Environmental Protection Agency (EPA) to update various parameters (e.g., process emissions factors, emissions abatement system destruction efficiencies) and methodologies for estimating PFC emissions from semiconductor operations. IBM plans to incorporate, as appropriate, the updated factors and methodologies at the conclusion of this industry and EPA effort in establishing its next generation PFC emissions reduction goal.

While our goal-setting process is underway, we continue to take actions to reduce our PFC emissions and monitor performance. Between 2010 and 2011, we reduced our PFC emissions by 2.8 percent -- primarily as a result of work at the Burlington, Vermont, facility where C2F6 was substituted by C4F8 in several chamber clean processes in the 200 mm fab. C4F8 is more fully utilized in the clean process and has a lower global warming potential than C2F6.

IBM also monitors two other materials with global warming potentials that are used in connection with manufacturing operations: 1) nitrous oxide (N2O), which is used in the manufacture of semiconductors but has lower global warming potential than the PFC gases; and 2) heat transfer fluids that are primarily used in tool-specific chiller units associated with manufacturing processes.

In addition to monitoring emissions, IBM continues to evaluate preferable replacements for these materials. At IBM's Burlington facility, a wafer test team completed a two-year project to qualify a new non-conductive heat transfer fluid used in tool-specific chiller units. The new fluid fills the microscopic air gaps between the wafer chuck and the physical wafer, on wafer test equipment. It has a lower vapor pressure and a lower global warming potential, resulting in fewer process fluid losses and reducing the metric tons of CO2e emitted from the process by more than two orders of magnitude and the fluid expense by over $100,000 a year.