Submicron Optical Lithography: I-Line Lens And Photoresist Technology

This paper presents submicron resolution test data from a wafer-stepper with a prototype Zeiss I-line lens (436 nanometers). The system demonstrates high-quality 0.5-micron lines and spaces on flat surfaces, and easily obtains 0.75-micron lines and spaces on a variety of surfaces. SEM data on step coverage and depth of focus are presented; process dependencies and special features of the 436-manometer light interaction with photoresist are highlighted. Theoretical expectations for resolution and depth of focus are experimentally shown to be valid, and extrapolations for future lenses promise even deeper penetration into the submicron region.