Case studies in energy use to realize ultra-high purities in semiconductor manufacturing

With increasing sophistication of products, there is a general trend towards higher purity (lower tolerances) in materials and parts. The purification of input materials and the need to create low-entropy environments in manufacturing lead to significant energy and materials use - referred to as secondary materialization. In this article we explore secondary materialization in semiconductor manufacturing by characterizing energy use trends for three cases: cleanrooms, producing ultrapure water (UPW), and purifying elemental gases. For purification of water and elemental gases, increasing purity standards are correlated with dramatic increases in energy use. For cleanrooms, while electricity use per square foot tends to increase with increasing air purity, this growth is cancelled by the evolution towards larger wafers and mini-environments. The net result is reductions in energy use per area of wafer processed when moving from 200 mm to 300 mm wafer processing. Given the continuing trend towards higher purity standards and growth in high-tech manufacturing, the high growth in secondary energy use suggests that the characterization and management of energy and materials use for purification deserves increased attention.