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Proceedings Paper

Line-profile and critical-dimension correlation between a normal-incidence optical CD metrology system and SEM
Author(s): Weidong Yang; Roger Lowe-Webb; Rahul Korlahalli; Vera Guorong Zhuang; Hiroki Sasano; Wei Liu; David Mui
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Paper Abstract

Process tolerances for critical dimensions are becoming increasingly severe as lithographic technology drives the minimum integrated-circuit feature size toward 0.1 micrometers and below. In response, Optical Critical Dimension metrology (OCD), an optical-wavelength light-diffraction technique, is currently undergoing an industry-wide evaluation as a fast, accurate, and non-destructive sub-100nm line-width monitor. As such, effective process monitoring requires detailed understanding of the correlation between CD-SEM and the OCD measurements. Correlation in CD measurements between the OCD technique and SEM techniques is investigated in this paper by measuring photo-resist gratings on a polysilicon gate film stack. Intra-grating CD variation is shown to account for scatter in the correlation plot. A positive offset in the correlation is also observed and a mechanism is proposed to account for the discrepancy. Correlation between CD-SEM and OCD is also demonstrated for samples with three different pitch sizes. A qualitative line-profile correlation between cross-section SEM (X-SEM) and OCD is presented for photoresist gratings in a Focus Exposure Matrix (FEM).

Paper Details

Date Published: 16 July 2002
PDF: 11 pages
Proc. SPIE 4689, Metrology, Inspection, and Process Control for Microlithography XVI, (16 July 2002); doi: 10.1117/12.473425
Show Author Affiliations
Weidong Yang, Nanometrics Inc. (United States)
Roger Lowe-Webb, Nanometrics Inc. (United States)
Rahul Korlahalli, Nanometrics Inc. (United States)
Vera Guorong Zhuang, Nanometrics Inc. (United States)
Hiroki Sasano, Applied Materials, Inc. (United States)
Wei Liu, Applied Materials, Inc. (United States)
David Mui, Applied Materials, Inc. (United States)

Published in SPIE Proceedings Vol. 4689:
Metrology, Inspection, and Process Control for Microlithography XVI
Daniel J. C. Herr, Editor(s)

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