Motorola's strategy for reducing PFC emissions

PFCs are used in the semiconductor industry for plasma etching and chamber cleaning. They were embraced because of their process performance and their low impact on employee safety. Etching high aspect ratio wafer features requires a source of fluorine ions and radicals, and carbon. Carbon is necessary to form F-C polymers which are deposited on feature walls to ensure anisotropic etching and on different substrates to provide etch selectivity. PFCs contain the right ratio of carbon and fluorine to etch substrates and deposit polymer. Chemistries such as F-2 and HF cannot be utilized by themselves for high aspect ratio plasma etching because they do not contain carbon necessary for polymer deposition. The Kyoto Protocol, the DuPont policy, and the Memorandum of Understanding (MOU) that many semiconductor manufacturers signed with the U.S. Environmental Protection Agency (EPA) are driving forces behind the reduction of PFC emissions. The Kyoto Protocol includes perfluorocarbons (PFCs), hydrofluorocarbons (HFCs) and sulfur hexafluoride (SF6 in the basket of greenhouse gases which are subject to emissions reduction requirements during 2008-2012. DuPont, the sole U.S. manufacturer of C2F6, issued a policy which requires industry to implement emissions reduction solutions in 1999. The EPA/MOU requires a two year technology development period tending Spring, 1998), after which time the industry will meet with EPA to discuss establishment of specific reduction targets. Japan, Europe and Korea have developed voluntary PFC emissions reduction initiatives for semiconductor operations in their countries similar to the EPA MOU. Motorola has worked proactively over the past five years to understand it's contribution to PFC emissions and to identify means for controlling emissions. This paper will summarize Motorola's research and development of PFC emissions reduction techniques. It will also discuss the factors that affect the application of reduction technologies. It will conclude with a discussion of Motorola's strategy for reducing PFC emissions.