A simplified but general model of wafer throughput for wafer steppers has been developed. The model shows clearly the throughput dependence on full-wafer overhead time, area of exposure field, alignment times, exposure time, and stage stepping time; trends are quite clear as to which parameters carry the most leverage, and which should therefore receive the resources for development. The model is used to compare the relative merits of two Zeiss lens series, a 5X wide-field lens and the standard 10X lens with regard to the anticipated IC production demands over the next five years. A case is made for the 5X lens, which can then later be replaced by the 10X lens.
Harry L. Stover,
"Near-Term Case For 5x Versus 10x Wafer Steppers", Proc. SPIE 0334, Optical Microlithography I: Technology for the Mid-1980s, (13 September 1982); doi: 10.1117/12.933561; https://doi.org/10.1117/12.933561