Life cycle inventory analysis and identification of environmentally significant aspects in semiconductor manufacturing

Intrinsically, semiconductor fabrication processes contain expensive and environmentally sensitive processes. The high purity requirements of input materials coupled with the extreme cleanliness of the processing environment provide a great challenge in managing the potential environmental impacts of this industry. High energy and water consumption and the throughput of hazardous auxiliaries give rise to additional environmental concerns. This paper presents a methodology for a life cycle inventory analysis (LCI) employed for a Motorola wafer fab. The LCI focuses on the generation of a complete data set of mass and energy flows for a wafer fab and the identification of environmentally significant aspects in wafer processing. Process modules within the infrastructure and the fab processes are identified as environmentally significant according to the consumption of energy, raw water, chemicals, gases and the origin of waste, wastewater, and emissions. The use of infrastructure facilities by fab processes is taken into account. The practical methodology worked out by Fraunhofer IZM and Motorola is a guideline to combine ecological and economical aspects and can be applied to realize environmental improvements within a company. The LCI data set is a basis for an impact assessment to gain LCA data for one of the most important processes in semiconductor fabrication. Corresponding methodologies for impact assessments are discussed.