Going for the green
07/01/2007
By Hank Hogan
Semiconductor wafer fabs tend to be one color, but now the industry wants another-green. At one of two back-to-back meetings held in mid-May in Austin, TX, members of the International SEMATECH Manufacturing Initiative (ISMI) agreed to draft a green fab standard, one designed expressly for semiconductor manufacturing. In the other workshop, ISMI members compiled a list of best practices to conserve energy in current fabs.
By going green, the industry could save substantial sums of money, notes ISMI’s environment, safety, and health technology project manager James Beasley. Estimates are that a one percent reduction in energy use in a standard facility can save $100,000 annually. “For the larger facilities, it may be even more. As the trend is toward ever larger facilities, there’s even more gain,” he says.
For existing facilities, recommendations included replacing compressor-based chillers with their solid-state counterparts. The switch would save energy while improving process control. Savings could also come from idling inactive vacuum pumps and from switching to electric pump motors. Right-sizing exhaust and air handling could also save energy, along with the use of more efficient equipment.
For new facilities, one possibility would be to incorporate advanced HVAC and heat recovery technologies. High-efficiency lighting could be another area that pays off.
One of the reasons why the industry is coming up with its own guidelines is that the Leadership in Energy and Engineering Design (LEED®) rating system established by the U.S. Green Building Council is intended for office buildings and the like. A wafer fab, assembly and test site, or flat-panel manufacturing plant is not your normal office building.
“A technology facility uses more ventilation, more energy, more water, and more resources per square foot than the typical building,” says Beasley.
Plans call for the new standard to complement LEED®, with specific additions that address the semiconductor area. The goal is to complete a draft and present the proposal to the council this year, with implementation in 2008.
Paul Westbrook, sustainable development manager for Texas Instruments (Dallas, TX), notes that TI ran into some issues regarding the current standard when the company constructed a LEED® certified facility in Richardson. With that fab commissioned and awaiting tool installation, Westbrook is now working on doing something similar in a test and assembly facility in the Philippines.
When going green, there are a number of similarities between a wafer fab and a test area. Both are controlled contamination environments, although fabs at ISO Class 3-5 are much more stringent in terms of cleanliness than ISO Class 6-8 test areas. Both have process tools, although test facilities pack in row after row of electricity-hungry probers. As a result, test areas face an added green challenge. “They can have a higher energy intensity than a cleanroom,” says Westbrook.
He adds, though, that green test and assembly areas could pay big dividends. Due to the growth in wafer size and shrinkage of devices, the number of new fabs needed won’t climb as fast as overall device output. The same, however, won’t be true in test and assembly areas.