Researchers at the University of Arizona sponsored by Semiconductor Research Corporation have developed new sensor and metrology technology that they say significantly reduces water usage and related energy usage in the manufacturing of semiconductors.
The SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing at the University of Arizona has created what the team calls “a sensor-based approach” that delivers a 30 percent savings in water and energy in the rinse and cleaning of “wafer” semiconductor materials.
According to SRC, surface preparation is one of the largest uses of water in semiconductor production and typically consists of three steps: 1) cleaning with specific chemicals suitable for the surface and materials that are being processed, 2) rinsing to remove the chemicals and by-products from the cleaning process, and 3) drying to remove water from the surface.
The current practice is recipe-based and not controlled with real-time, in-line monitoring of the progress of the process steps, the group says. Since there is no in-line, real-time metrology, there is no real-time feedback, nor control. The processes are typically conducted with a very large cushion of safety to overcome lack of regulation. This sizeable safety factor creates unnecessary waste of chemicals, water and energy—much more than what the processes actually need when controlled properly, SRC says.
The ERC’s new approach uses real-time monitoring of the wafer’s surface to curb excessive use of resources. The water use figures currently apply to current cleaning processes for 300 millimeter silicon wafers, but SRC expects improvements to be especially beneficial to chipmakers as they enter into fabrication with much larger, next-generation 450mm surface areas.
According to SRC, the collective chip industry’s International Technology Roadmap for Semiconductors has an agreed goal of lowering resource utilization for both immediate and next-generation fabrication processes. Among the environmental challenges that the industry will face in the move to 450mm wafers is how to hold down costs and materials needed for cleaning and preparing a surface that’s more than twice the size of the current state-of-art wafer, SRC says.
A report released in June showed that semiconductor manufacturing plants dramatically reduced their average energy use from 1997 to 2011.
Worldwide Fab Energy Study by the International Sematech Manufacturing Initiative found that energy consumed by process equipment in 2011 was half that of 1997 levels.