Process Latitude Modeling For Submicron G- And I-Line Lithography

We have evaluated both present and future G-- and I--line lenses by considering their process sensitivity in 0.9-micron lithography. This was accomplished using a modified and automated version of the U. C. Berkeley simulation program SAMPLE. Our results indicate that resist development latitudes are much more sensitive indicators of lens performance than sidewall angle and thickness contrast. When properly defined, they are also relatively insensitive to standing wave effects. Using a single layer of the AZ1350J 6-line resist for all our comparisons, we find the 0.38 numerical aperture 6-line and the 0.42 I-line lenses give superior latitudes. The 0.28 6-line lense provides inadequate development latitudes for reliable submicron patterning. Details regarding opening latitude, base latitude, top latitude, metrology ratio, sidewall angle, thickness contrast, and exposure dose in response to variations in numerical aperture, wavelength, base nodality, and top nodality are presented.