EXCIMER LITHOGRAPHY FOR ULSI

A brief review of excimer lithography for ULSI is presented with an em phasis on the recent progress made in KrF excimer stepper technology. In particular, the types of projection optics, excimer laser and the r elated performance of steppers are explained in detail. The resist pat terns obtained with a recent excimer stepper are shown. Although there are many problems to be overcome for future lithography, it is antici pated that not only 0.35 mum design rules but also 0.20 to 0.25 mum de sign rules will be achieved using excimer lasers.