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Proceedings Paper

Scatterometry for 0.24-0.70 um developed photoresist metrology
Author(s): Michael R. Murnane; Christopher J. Raymond; Steven L. Prins; S. Sohail H. Naqvi; John Robert McNeil
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Paper Abstract

Scatterometry, the characterization of periodic structures via diffracted light analysis, is shown to be a viable and versatile metrology for critical dimensions as small as 0.24 micrometers . Scatterometry is rapid, nondestructive, inexpensive, and potentially useful for on- line control during several microlithographic processing steps. This paper discusses two recent studies in which scatterometry was applied to the measurement of developed photoresist patterns. First, scatterometric measurements of developed resist lines in the 0.38 micrometers to 0.70 micrometers range will be presented. Results from four sample wafers are shown to be consistent with SEM measurements. For one wafer, the average deviation of scatterometry linewidth measurements form top-down SEM measurements, over a broad exposure range, is 14.5 nm. Moreover, our scatterometer is shown to be highly linear with the SEM; linearity coefficients have typically been above 0.99. The goal of our second project has been to determine whether scatterometry measurements are affected by variations in the integrated circuit production process. A set of twenty-five wafers was fabricated with deliberate variations in the exposure dose and the underlying film thicknesses. We are presently investigating the effects of the film thicknesses on the measurements of critical dimensions (CDs) as small as 0.24 micrometers . Preliminary results indicate that CDs and multiple thin films can be simultaneously measured by applying multi-parameter prediction algorithms to the scattered light data. Results from four different prediction algorithms are given. Finally, the repeatability of the scatterometer is shown to be excellent: 0.5 nm for consecutive measurements and 0.8 nm for day-to-day measurements. The results of an extensive repeatability/precision experiment are presented.

Paper Details

Date Published: 22 May 1995
PDF: 10 pages
Proc. SPIE 2439, Integrated Circuit Metrology, Inspection, and Process Control IX, (22 May 1995); doi: 10.1117/12.209227
Show Author Affiliations
Michael R. Murnane, Univ. of New Mexico (United States)
Christopher J. Raymond, Univ. of New Mexico (United States)
Steven L. Prins, Univ. of New Mexico (United States)
S. Sohail H. Naqvi, Univ. of New Mexico (United States)
John Robert McNeil, Univ. of New Mexico (United States)

Published in SPIE Proceedings Vol. 2439:
Integrated Circuit Metrology, Inspection, and Process Control IX
Marylyn Hoy Bennett, Editor(s)

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