Measures and trends in energy use of semiconductor manufacturing

We analyze trends in electricity use to fabricate typical Intel CPUs from 1995 to 2005. Two sets of energy consumption data for semiconductor fabrication were collected: from the annual survey of manufacturers (ASM) of the U.S. Census and annual reports from the Taiwanese semiconductor manufacturer UMC. Analysis indicates that the difference between the two data sources is small despite being very different aggregations of device production and geographical location. We combine this information with technical specifications of Intel CPUs to measure trends in energy use according to two different functional units. The first measure, electricity use per transistor, displays rapid and sustained decreases, with 98% reduction from 1995 to 2005. This behavior is reminiscent of Moorepsilas Law and reflects rapid technological progress in the industry. The second measure, electricity use per typical CPU for a given year (e.g. Pentium II for 1998), displays fluctuations but surprisingly is roughly constant over the 10-year period. The explanation for this constant behavior is that while technological progress reduces the energy use per transistor, it also enables demand for more powerful chips which contain many more transistors. The two effects, according to this analysis, roughly balance. We do not interpret this result as a lack of effort of the industry to pursue energy efficiency, rather as a fundamental dynamic for sectors in which processes and products are co-evolving. This result calls for a rethinking of how we conceptualize and benchmark efficiency improvements in rapidly evolving sectors.