by Dr. Paula Doe, SEMI Emerging & Adjacent Markets
June 29, 2011 – At $10, long life and low energy use make LED lighting costs compelling for the consumer. Despite major recent progress, however, current prices are closer to $40.
"Improvements in device efficacy have been driving big improvements in lumens per dollar, but that’s getting close to the theoretical maximum — there’s not room to double it again, but costs still need to come down much more than that," says Bryan Bolt, Cascade Microtech’s director of technology development. "So that means it’s now all about manufacturing efficiency — things like designing devices that are easy to manufacture, and improving cost-of-ownership of equipment." Better wafer-level testing is one area that can have a big impact on reducing costs by avoiding the high cost of packaging for bad die. Also key will be bringing traceability to test, for tracking defects back to root causes. But for test suppliers to deliver traceability, the sector will need to come to some degree of consistency in operating conditions and performance parameters from the wide range of different probers, spectrometers, integrating spheres, and software now put together in different combinations by individual LED makers.
Better measurement of process conditions can also improve yields. Veeco Instruments chief technologist Bill Quinn reports that test results using the near UV pyrometer developed with Sandia National Lab to monitor the temperature of the transparent and often warped sapphire wafer directly during epitaxial deposition — instead of just the temperature in the pocket in which it sits — are showing potential to improve yields even in a well-controlled manufacturing environment. With each 2