| Abstract: |
We at the National Institute of Standards and Technology are building a metrology instrument called the Molecular Measuring Machine (M3) with the goal of performing nanometer-accuracy, two-dimensional, point-to-point 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 vertical measurement range is 5 ?m using a calibrated capacitance gage sensor. The instrument includes temperature control with millidegree K 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 expanded uncertainty of the average pitch of 50 x 10-6. This fractional uncertainty is derived from an analysis of the sources of uncertainty for a 1 mm measurement, including the effects of alignment, Abb? errors, motion cross-coupling, and temperature variations. |
