Mask limitations to VLSI: overlay accuracy and linewidth variation : Monroe J. Cowan. Solid St. Technol., 55 (May 1982)

Abstract

The lithographic performance of IBM Spectralith, Hoechst AZ 7110, and Hoechst AZ 5214E in image reversal mode was evaluated on a Nikon body 7 0.45NA i-line stepper. All 3 resists are capable of resolving 0.45 μm lines and spaces, printing linearly down to 0.45 μm with zero bias, and show at least 1.5 μm depth of focus. The photospeed of Spectralith and AZ 7110 is around 150 mJ/cm2, and their exposure latitude is 32 %, for 0.5 μm lines/spaces. AZ 5214E in image reversal mode is 3 times faster, prints 0.5 μm patterns to nominal at only 45 mJ/cm2, and also shows a significantly wider exposure latitude of 52 % (again for 0.5 μm patterns). In conclusion a 0.5 μm technology can be run on today's i-line steppers with these resists.