Unique optical design features were incorporated into the Model 900 Projection Stepper. The f/4 illuminator uses a pulsed 200 w mercury short arc lamp and a glass light pipe to achieve a uniform intensity of .5 w/cm² at the reticle. The 1:1 projection lens is a folded, double-pass design which consists of a concave mirror and a cemented achromat-prism assembly. With a numerical aperture of .30, the lens achieves diffraction-limited performance at both the g and h mercury lines. Reticle to wafer alignment is detected through the lens and corrected automatically at each exposure step.

Date Published: 5 September 1980
PDF: 7 pages
Proc. SPIE 0221, Developments in Semiconductor Microlithography V, (5 September 1980); doi: 10.1117/12.958622

Published in SPIE Proceedings Vol. 0221:
Developments in Semiconductor Microlithography V
James W. Dey, Editor(s)