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Proceedings Paper

Alignment performance versus mark quality
Author(s): Joseph P. Kirk; Jung H. Yoon; Timothy J. Wiltshire
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Paper Abstract

A procedure is described for preparing relief alignment marks with precisely degraded quality that are then used to calibrate alignment performance. Alignment degrades with mark quality, eventually failing when the marks are no longer found. Using conventional processes it is difficult to accurately find this threshold and virtually impossible to experimentally establish the functional relationship between alignment mark quality and alignment precision. Marks that simulate a full range of process conditions, including planarization and granularity, are formed utilizing the continuous tone relief response of I-line photoresist to (lambda) equals 248 nm dose, thereby avoiding the complication of fabricating wafers through selective steps of the actual semiconductor manufacturing process. The usual box in box overlay measurement problem, caused by boxes formed by different processes, is avoided by printing high contrast overlay evaluation structures regardless of the alignment mark quality. Overlay is measured and plotted as a function of mark quality and the lithography engineer knows precisely the condition of the alignment system. For example; it is easily established by direct measurement the alignment system's ability to control magnification as the relief of the alignment marks change.

Paper Details

Date Published: 29 June 1998
PDF: 6 pages
Proc. SPIE 3334, Optical Microlithography XI, (29 June 1998); doi: 10.1117/12.310777
Show Author Affiliations
Joseph P. Kirk, IBM Microelectronics Div. (United States)
Jung H. Yoon, IBM Microelectronics Div. (United States)
Timothy J. Wiltshire, IBM Microelectronics Div. (United States)

Published in SPIE Proceedings Vol. 3334:
Optical Microlithography XI
Luc Van den Hove, Editor(s)

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