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Proceedings Paper

Physical matching versus CD matching for CD SEM
Author(s): Roman Kris; Galit Zuckerman; Elad Sommer; Zion Hadad; Shalev Dror; Aviram Tam; Naftali Shcolnik
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Paper Abstract

CD-SEMs fleet matching is a widely discussed subject and various approaches and procedures to determine it were described in the literature. The different approaches for matching are all based on statistical treatment of regular CD measurements that are performed on dedicated test structures. The test structures are a limited finite set of features, thus the matching results should be treated as valid only for the specific defined set of test features. The credibility of the matching should be in question for different layers and specifically production layers. Since matching is crucial for reliable process monitoring by a fleet of CD-SEMs, the current matching approaches (such as TMU) must be extended so that the matching will be only tool dependent and reproducible on all layers regardless their specific material or topographic characteristics. In this work the term "Physical Matching" is introduced and a new matching procedure based on physical parameters is described. This approach extends the conventional matching methods to enable significant improvement of the matching between CD-SEM tools in production environment. To study and demonstrate the physical matching, we focus on the limited parameters set - the image brightness and Signal/Noise ratio(SNR). We test the sensitivity of CD measurements to changes in these parameters both on different test layers - Etch and Litho. We show that sensitivity of CD based measurements is low and reasonable change of the image brightness or SNR has small effect. The advantage of the physical matching approach for case study is demonstrated. The improved matching procedures are based on new targets that are used to measure the above image parameters directly. This way it is possible to characterize correctly the physical state of the measurement tool and guarantee the same image characteristics which in turn guarantee improved matching on all layers. In the framework of the proposed matching approach a proper determination of the minimal set of physical parameters that is needed to guarantee CD-SEM tools stability and matching should be included.

Paper Details

Date Published: 12 April 2007
PDF: 12 pages
Proc. SPIE 6518, Metrology, Inspection, and Process Control for Microlithography XXI, 65180O (12 April 2007); doi: 10.1117/12.711768
Show Author Affiliations
Roman Kris, Applied Materials Israel (Israel)
Galit Zuckerman, Applied Materials Israel (Israel)
Elad Sommer, Applied Materials Israel (Israel)
Zion Hadad, Applied Materials Israel (Israel)
Shalev Dror, Applied Materials Israel (Israel)
Aviram Tam, Applied Materials Israel (Israel)
Naftali Shcolnik, Applied Materials Israel (Israel)

Published in SPIE Proceedings Vol. 6518:
Metrology, Inspection, and Process Control for Microlithography XXI
Chas N. Archie, Editor(s)

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