Very high registration accuracy is required for 5:1 wafer steppers used in V-LSI production. The image quality of an alignment mark is affected by illumination wavelength, photoresist thickness, light absorption in the photoresist, and by the characteristics of the alignment mark itself. Reflection Modeling and image profile analysis are applied to evaluate the influence of the alignment geometry and image quality on the ability to align the wafer. As a result of this study, ideal image quality is observed by optimization of the step height, and the influence of background noise is studied on rough aluminum surfaces. Degradation of the image profile and edge contrast are observed on rough aluminum surfaces.

Date Published: 29 June 1984
PDF: 7 pages
Proc. SPIE 0470, Optical Microlithography III: Technology for the Next Decade, (29 June 1984); doi: 10.1117/12.941890

Published in SPIE Proceedings Vol. 0470:
Optical Microlithography III: Technology for the Next Decade
Harry L. Stover, Editor(s)