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THOUSAND OAKS, Calif., and HSINCHU TAIWAN, AUGUST 22, 2002 - Rockwell Scientific Company LLC (RSC) and UMC (NYSE: UMC) today announced the successful development of the HAWAII-2RG, a readout integrated circuit (ROIC) designed by RSC and fabricated by UMC based on its cutting edge mixed-mode CMOS process and precision stitching technique. The project was funded by the NASA Ames Research Center through a contract with the University of Hawaii.
The 40 mm x 40 mm chip is being used with infrared detectors developed by RSC to produce astronomy focal plane arrays (FPAs) with a base resolution of 4.2 million pixels and mosaic resolution of 16.8 million pixels. Applications that will utilize the infrared imaging sensor include several of the world's largest ground-based telescopes; the arrays are also one of the candidates for NASA's Next Generation Space Telescope (NGST).
RSC produces the FPA by bonding the HAWAII-2RG readout to a matching 2048 by 2048 infrared detector array fabricated in Mercury Cadmium Telluride (HgCdTe). The result is one of the world's largest and highest performance infrared sensors, with 60 percent larger area than 35 mm film.
"UMC did a fantastic job of fabricating the HAWAII-2RG, which is one of the largest single chips ever produced with high yield. More impressively, the device worked successfully upon its first silicon pass. We are committed to further efforts with UMC as the foundry continues to enable the evolution of our large imaging sensors that require many millions of pixels for ground- and space-based astronomy," commented Kadri Vural, vice president of the imaging division at Rockwell Scientific. RSC already has several orders for the Hawaii-2RG sensors from the world's most advanced ground-based observatories.
NASA is also seeking a way to produce infrared sensor mosaics for its Next Generation Space Telescope (NGST). The NGST, the successor to the Hubble Space Telescope, is planned for launch in 2010. The project will orbit a six-meter class telescope at the Lagrangian L-2 point, far beyond the moon's orbit. If selected for flight, sets of four HAWAII-2RG infrared FPAs would be closely butted to make 4096 x 4096 mosaics for NGST, the most advanced infrared mosaics ever made.
Because state-of-the-art CMOS wafer foundries can only fabricate ICs that are about a quarter of the area of the HAWAII-2RG, UMC's engineers "stitch" the large CMOS readout using a series of exposures, each of which captures a section of the entire readout. The result is a 40 mm x 40 mm die with an ultra-precise alignment of the sub-micron electrical lines between adjacent sections to seamlessly transmit signals across the many stitching boundaries.
While large CCDs and CMOS ICs have been made using less sophisticated forms of photolithographic stitching, UMC used its deep submicron expertise and tools to achieve alignment accuracy better than 0.1 micron with unprecedented production yield. Scanning electron microscopy confirmed the astoundingly accurate and precise alignment achieved by UMC. Each 200 mm silicon wafer holds only twelve of the very large ICs.
"UMC is committed to expanding its foundry business with emerging products such as CMOS-based imaging sensors with innovators such as RSC. In fact, we have already engaged with RSC on technical developments for its potential involvement in the Next Generation Space Telescope, and CMOS sensors for HDTV cameras," said Fu Tai Liou, chief officer of worldwide marketing and sales at UMC.
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