Abstract

Over the past 16 years, eight generations of dynamic random access memory (DRAM) have been manufactured with each new generation delivering 4× more bits than the last. The 1-kbit DRAM of 1975 has steadily evolved into the 16-Mbit DRAM of today, driving steady advances in lithographic technology. Optical lithography has been used to manufacture all these DRAM generations, and is likely to extend another two or three generations. Optical lithographic tools are marvels of precision engineering with optics capable of projecting 2 billion pixels (distorted by <1/10 pixel) and with stages capable of positioning a 200-mm wafer to within 20 nm of any desired location.

© 1991 Optical Society of America