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Proceedings Paper

Contact hole characterization by SEM waveform analysis
Author(s): Douglas G. Sutherland; Andrei Veldman; Zoe A. Osborne
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Paper Abstract

A new algorithm for an Applied Materials CD-SEM metrology tool has been developed which gives a quantitative characterization of the quality of contact holes in photoresist. This is a non-destructive technique that allows users to assess the cross sectional profile of a contact hole from top-down measurements thus avoiding the time- consuming and expensive task of measuring cross sections. This analysis is based on the shape of the SEM waveform that is created when a contact hole is measured. The algorithm generates a numerical grade for the contact profile, which is based on the shape of the waveform. The classification of the contact hole into different Profile Grades can then be determine due to the strong correlation between the shape of the waveform and the cross-section profile of the contact hole. The Profile Grades have been found to be in excellent agreement with SEM cross-sections. When this technique is applied to contact holes across a focus-exposure matrix wafer, the algorithm gives grades which clearly delimit the domain in which the process parameters produce open, sharp- edged contacts. In many cases it was found that the CD measurement alone was insufficient to determine if a given contact hole was actually open. The combination of the CD measurements with the profile grades is a particularly powerful tool to determine ideal process parameters for lithography, and determination of the profile grades becomes essential as tool-sets are pushed toward the limits of their capability. The following paper contrast on 250 nm contact holes but presents data on contact holes ranging in size from 200 nm to 500 nm.

Paper Details

Date Published: 14 June 1999
PDF: 6 pages
Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999); doi: 10.1117/12.350819
Show Author Affiliations
Douglas G. Sutherland, Cypress Semiconductor (United States)
Andrei Veldman, Applied Materials (Israel) (United States)
Zoe A. Osborne, Applied Materials (United States)

Published in SPIE Proceedings Vol. 3677:
Metrology, Inspection, and Process Control for Microlithography XIII
Bhanwar Singh, Editor(s)

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