ABSTRACT
Photolithography allows very complex micro- and nanostructures to be built by copying a pattern from a photomask to a wafer. For both shadow printing and projection lithography systems, the shaping of the illumination light is based on micro-optical components. Micro-optical components like refractive microlens arrays and diffractive optical elements allow the illumination light to be freely shaped with little loss. This chapter discusses the design, manufacturing, testing, and system integration of the micro-optical key components used for light shaping in photolithography. It explains the early days of photolithography and its decisive role for semiconductor industry. The filament lamps used in early mask aligners did not provide enough light. They were replaced by more powerful high-pressure gas-discharge lamps. In early mask aligners, a ground glass diffuser was placed in or near the secondary focal point of the ellipsoid mirror for light mixing. A significant advance on the glass-molded integrator was lens array integrators, comprising some individual lenses mounted in a frame.
