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Proceedings Paper

Scatterometric sensor for lithography
Author(s): Christopher J. Raymond; Michael R. Murnane; S. Sohail H. Naqvi; John Robert McNeil
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Paper Abstract

Scatterometry, the analysis of light scattered by diffraction from periodic structures, is shown to be a versatile process control and metrology technique for use in microelectronics manufacturing. Contemporary inspection technologies, such as scanning force microscopy (SFM) and scanning electron microscopy (SEM), in general cannot be performed in-situ and are slow for real-time process control. Scatterometry, on the other hand, is rapid, nondestructive, inexpensive and might be used on-line. This paper will discuss applications of 2 - (Theta) scatterometry to developed photoresist focus/exposure matrices, often related to the manufacture of microelectronic devices. To test this technique we obtained and measured five identically processed wafers with nominal 0.5 micrometers line/0.5 micrometers space grating patterns. Each wafer is comprised of gratings created in Shipley 89131 negative photoresist and arranged in a matrix of incremental exposure doses and focus settings. The scatterometric CD measurements are consistent in comparison to cross- section and top-down SEM measurements of the same structures. The average deviation of 11 linewidth measurements from top down SEM measurements, over a broad exposure range, is 14.5 nm. In addition, the repeatability (1 - (sigma) ) of the 2 - (Theta) scatterometer is shown to be excellent: 0.5 nm for consecutive measurements and 0.8 nm for day to day measurements.

Paper Details

Date Published: 16 September 1994
PDF: 13 pages
Proc. SPIE 2336, Manufacturing Process Control for Microelectronic Devices and Circuits, (16 September 1994); doi: 10.1117/12.186798
Show Author Affiliations
Christopher J. Raymond, Univ. of New Mexico (United States)
Michael R. Murnane, 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. 2336:
Manufacturing Process Control for Microelectronic Devices and Circuits
Anant G. Sabnis, Editor(s)

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