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Publication Citation: Toward Nanometer Accuracy Measurements

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Author(s): John A. Kramar; E Amatucci; David E. Gilsinn; Jay S. Jun; William B. Penzes; Fredric Scire; E C. Teague; John S. Villarrubia;
Title: Toward Nanometer Accuracy Measurements
Published: June 01, 1999
Abstract: We at NIST are building a metrology instrument called the Molecular Measuring Machine (MMM) with the goal of performing 2D point-to-point measurements with one nanometer accuracy cover a 50 mm by 50 mm area. The instrument combines a scanning tunneling microscope (STM) to probe the surface and a Michelson interferometer system to measure the probe movement, both with sub-nanometer resolution. The instrument also feature millidegree temperature control at 20 degrees C, an ultra-high vacuum environment with a base pressure below 10^(-5) Pa, and seismic and acoustic vibration isolation. High-accuracy pitch measurements have been performed on 1D gratings. In one experiment, the MMM STM probe imaged an array of laser-focused, atomically deposited chromium lines over an entire 5 micrometers by 1 mm area. Analysis of the data yielded an average line spacing of 212.69 nm with a 5 pm standard uncertainty. The uncertainty estimate is derived for an analysis of the sources of uncertainty for a 1 mm point-to-point measurement, including the effects of alignment, Abbe offset, motion cross-coupling, and temperature variations. In another measurement, the STM probe continuously tracked a holographically-produced grating surface for 10 mm, counting out 49,996 lines and measuring an average line spacing of 200.011 nm with a 5 pm standard uncertainty.
Conference: Poster Session
Proceedings: Proceedings of SPIE, Metrology, Inspection, and Process Control for Microlithography XIII, Bhanwar Singh, Editor
Volume: 3677
Pages: pp. 1017 - 1028
Location: Santa Clara, CA
Dates: March 15, 1999
Keywords: length metrology,Michelson interferometry,scanning tunneling microscopy
Research Areas: Metrology, Manufacturing