Grating Pitch Measurements With the Molecular Measuring Machine
John A. Kramar, Jay S. Jun, William B. Penzes, Fredric Scire, E C. Teague, John S. Villarrubia
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.
Proceedings of SPIE,
July 21, 1999
Optical Disk Testing Methodologies II and Optical Disk Drive Characterization
, Jun, J.
, Penzes, W.
, Scire, F.
, Teague, E.
and Villarrubia, J.
Grating Pitch Measurements With the Molecular Measuring Machine, Proceedings of SPIE,, Denver, CO
(Accessed June 5, 2023)