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Screening Candidates for 30 nm Spheres.

pdf icon Screening Candidates for 30 nm Spheres. (103 K)
Donnelly, M. K.; Yang, J. C.

NISTIR 7345; 7 p. August 2006.


spheres; particles; calibration; particle size distribution; uncertainty; Standard Reference Materials


This paper describes the preliminary screening process that was conducted to identify potential candidate particles available from commercial sources to be used as National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for 30 nm spheres. Five different samples were obtained and measured using the NIST particle calibration facility. The sample with the narrowest size distribution and a preliminary peak particle diameter of 30.1 nm was identified as a potential candidate to become the NIST 30 nm SRM. A secondary candidate, with a fairly narrow distribution and a peak particle diameter of 24.2 nm was also identified. Further studies to address accuracy issues and ensure repeatability are recommended. An initial screening process to identifY candidate particles that could be used as the NIST Standard Reference Material (SRM) 30 om spheres was conducted. NIST currently has polystyrene latex (PSL) spheres available as SRMs as small as 60 om. The SRM particles are used primarily by the semiconductor industry to calibrate and test metrology instruments. The Semiconductor Industry Association has developed an International Technology Roadmap for Semiconductors (ITRS) specifying the need for smaller reference materials as semiconductor components and devices become smaller. The ITRS discusses critical semiconductor components scaling to 32 nm or smaller by as early as 2008.