Solid state: X-ray lithography breaks the submicrometer barrier; A new X-ray lithography system allowed Bell Labs engineers to make the smallest, fastest MOSFETs yet reported

Describes an X-ray lithography system which allowed Bell Labs. engineers to make MOSFETs with channel lengths of 0.3 to 0.4 micrometers, switching speeds of 30 to 75 picoseconds, and speed-power products of 5 femtojoules (5×10^-15 Ws) to 50 femtojoules. The X-ray system is smaller, less expensive, and more reliable than previous X-ray systems, and it also has a higher throughput-potentially 75 wafers per hour. It uses an exposure power of 4.5 kW, compared to the 20 to 40 kW in other systems. The key to a short exposure time with a low power source is the use of a novel resist that is more radiation-sensitive than conventional resists. Another advantage of the system is exceptional linewidth control-better than 0.1 micrometer across the wafer.