14 June 1999 Toward nanometer accuracy measurements
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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.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John Kramar, John Kramar, Edward Amatucci, Edward Amatucci, David E. Gilsinn, David E. Gilsinn, Jau-Shi Jay Jun, Jau-Shi Jay Jun, William B. Penzes, William B. Penzes, Fredric Scire, Fredric Scire, E. Clayton Teague, E. Clayton Teague, John S. Villarrubia, John S. Villarrubia, } "Toward nanometer accuracy measurements", Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999); doi: 10.1117/12.350791; https://doi.org/10.1117/12.350791

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