Screening Candidates for 30 nm Spheres.
Screening Candidates for 30 nm Spheres.
(103 K)
Donnelly, M. K.; Yang, J. C.
NISTIR 7345; 7 p. August 2006.
Keywords:
spheres; particles; calibration; particle size
distribution; uncertainty; Standard Reference Materials
Abstract:
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.
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