Parametric studies and the operating latitude of a spectrally narrowed KrF excimer laser for the deep-UV stepper

With the near certainty that the excimer stepper will become one of the lithography tools for printing sub -0.4 micrometers design rule features, it has now become imperative to better understand the performance characteristics of the excimer laser in the context of the total lithography process. It is no longer possible to treat the laser in isolation from the stepper or the resist. The cost of operation for the laser is integrally tied with the stepper specifications, design rule requirements, and resist characteristics. This paper discusses the dependence of laser parameters on stepper performance, and the relationship between various laser operating parameters and specification. In addition, it analyzes the combination of the laser to the lithography process cost per wafer level in terms of design rule requirements and resist characteristics. 15