Deep-ultraviolet lithography for 500-nm devices

Each DRAM design generation has required higher reoiution imaging and overlay capability. The 500-nm lithographic ground rules of a 16-Mb chip make deep-UV (DUV) an attractive alternative to,thc more stanth,rd mid-UV (MUV) photolithography presently practiced for less demanding technologies. The shorter wavelength permits an unproved depth of focus by allowing the same resolution at smaller numerical apertures. This approach retains the simplicity of single-layer-resist processing rather th a ii forcing conversion to m ultilayer imaging.