Novel Method Puts CMOS Imagers in Stitches

In the battle of the image sensors, Tower Semiconductor Inc. of Migdal Haemek, Israel, has developed a production method that should help complementary metal oxide semiconductor (CMOS) sensors compete with charge-coupled devices (CCDs). The foundry has introduced a stitching process that allows CMOS sensors to avoid size limitations imposed in production by the exposure field in photolithography equipment, enabling higher resolutions through a chip's higher pixel count.
The method lines up several design exposures on a wafer, fusing them into a single sensor. Although similar stitching methods are used for CCD arrays, noted Reuven Marko, Tower's vice president of marketing and sales, this is the first development of the method for CMOS technology. Also, large CMOS arrays should produce better yields than the CCD sensors, he said, because the CMOS pixels are not electrically coupled.