Toward the global optimum in lithographic lens design

Abstract

Significant advances have been made in recent years in the development of lithography optics. The resolution of structures smaller than 45 nm demanded a new class of catadioptric objective lenses whose design and construction is the result of decades of development in lithography optics. This article describes the best-performing lens types and design principles of the catadioptric concept of these lenses.

Aberration theory: still the key to designing superior optical systems

“…Many designs encompassing refractive, reflective, and catadioptric (combining both) systems have been proposed since the onset of lithographic lens design in the early 1960s. 8 Correction of Petzval, a type of third-order aberration, is a major limitation of purely refractive designs. It is commonly corrected using a negative-powered lens near the focal plane.…”