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Proceedings Paper

ASM stepper alignment through thick epitaxial silicon films
Author(s): Iain Black
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Paper Abstract

High voltage bipolar and BiCMOS processes often use thick epitaxially grown layers of silicon. These films 12-24 micrometers thick offer a considerable challenge to the alignment of subsequent process layers due to the 'wash out' and image distortion, caused to any underlying pattern, which render automatic alignment mark recognition difficult it not impossible. Historically using projection aligner technology these immediately post Epi layers have been manually aligned with future automatic alignment target defined at the first opportunity post Epi. This is not possible using ASM steppers, as these depend upon marks etched into the silicon, before first processing, to create marks, to which all subsequent layers are registered. To allow the stepper to run wafers with these Epi films a new approach was required.

Paper Details

Date Published: 28 April 1999
PDF: 11 pages
Proc. SPIE 3741, Lithography for Semiconductor Manufacturing, (28 April 1999); doi: 10.1117/12.346892
Show Author Affiliations
Iain Black, National Semiconductor Ltd. (United Kingdom)

Published in SPIE Proceedings Vol. 3741:
Lithography for Semiconductor Manufacturing
Chris A. Mack; Tom Stevenson, Editor(s)

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