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Proceedings Paper

Dimensional metrology with the NIST calibrated atomic force microscope
Author(s): Ronald G. Dixson; Rainer G.J. Koening; Vincent Wen-Chieh Tsai; Joseph Fu; Theodore V. Vorburger
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Paper Abstract

AFMs are increasingly used in the semiconductor industry as tools for sub-micrometer dimensional metrology. The scale of an AFM must be calibrated in order to perform accurate measurements. We have designed and developed the calibrated AFM (C-AFM) at the NIST to calibrate standards. Specifically, our primary calibrations are expected to be of combined pitch/height, or 3D magnification standards for AFM. THe C-AFM has metrology traceable to the International System of Units meter for all three axes. This is accomplished through the integration of a flexure x-y translation stage, heterodyne laser interferometers, and a z-axis piezoelectric actuator with an integrated capacitance sensor. Our first pitch measurements for an outside customer were recently compete, in which we were able to report relative expanded uncertainties as low as 1 percent on sub- micrometer pitches. The uncertainty budget for these measurements includes the effect of sample non-uniformity, which is the dominant contribution for some of the reported uncertainties. Four samples were measured - two with grid patterns and two with grid recently made considerable improvements in our uncertainty budget for step height measurements. For example, we recently achieved 0.2 nm expanded uncertainty on a 20 nm step, and achieved 0.008 nm expanded uncertainty in the measurement of the approximately 0.3 nm single atom step on Si. We also participated in the recently competed first round of the NIST linewidth correlation project, in which linewidht measurements obtained from different methods are compared. In this paper, we will report on the current status of the C-AFM, and on our plans for further development.

Paper Details

Date Published: 14 June 1999
PDF: 15 pages
Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999); doi: 10.1117/12.350822
Show Author Affiliations
Ronald G. Dixson, National Institute of Standards and Technology (United States)
Rainer G.J. Koening, National Institute of Standards and Technology (Germany)
Vincent Wen-Chieh Tsai, National Institute of Standards and Technology (United States)
Joseph Fu, National Institute of Standards and Technology (United States)
Theodore V. Vorburger, National Institute of Standards and Technology (United States)


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

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