Segment Alignment Illumination System
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
In step-and-repeat tools used in photolithographic processes for micro-circuit fabrication, the energy source for exposing photoresist is nearly always a mercury arc lamp because it has a high radiant emittance at several wavelengths that is unmatched by other sources. This property is required in order to make effective use of the high resolution lenses employed in these tools. Normally only one of these wavelengths is used. The undesired wavelengths are filtered out from the system, and are dissipated in some cooling system.