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Publication Citation: Grating Pitch Measurements With the Molecular Measuring Machine

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Author(s): John A. Kramar; Jay S. Jun; William B. Penzes; Fredric Scire; E C. Teague; John S. Villarrubia;
Title: Grating Pitch Measurements With the Molecular Measuring Machine
Published: November 01, 1999
Abstract: At the National Institute of Standards and Technology, we are building a metrology instrument called the Molecular Measuring Machine (M^3) with the goal of performing nanometer- accuracy two-dimensional feature placement measurements over a 50 mm by 50 mm area. The instrument uses a scanning tunneling microscope to probe the surface and an interferometer system to measure the lateral probe movement, both having sub-nanometer resolution. The continuous vertical measurement range is 5 micrometer, and up to 2 mm can be covered by stitching overlapping ranges. The instrument includes temperature control with millikelvin stability, an ultra-high vacuum environment with a base pressure below 10^(-5) Pa, and seismic and acoustic vibration isolation. Pitch measurements were performed on gratings made by holographic exposure of photoresist and on gratings made by laser-focused atomic deposition of Cr. The line pitch for these gratings ranged from 200 nm to 400 nm with an estimated standard uncertainty of the average pitch of 25 X 10^(-6). This fractional uncertainty is derived from 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. These grating pitch measurements are uniquely accomplished on M^3 because of the combination of probe resolution and long-range interferometer-controlled stage. This instrument could uniquely address certain dimensional metrology needs in the data storage industry.
Conference: Optical Disk Testing Methodologies II and Optical Disk Drive Characterization
Proceedings: Proceedings of SPIE,
Volume: 3806
Pages: pp. 46 - 53
Location: Denver, CO
Dates: July 21, 1999
Keywords: dimensional metrology;Michelson interferometry;scanning tunneling microscopy
Research Areas: Metrology, Manufacturing