Selection of Calibration Particles for Scanning Surface Inspection Systems.
Selection of Calibration Particles for Scanning Surface
Inspection Systems.
(13917 K)
Mulholland, G. W.; Bryner, N. P.; Liggett, W.; Scheer,
B. W.; Goodall, R. K.
Flatness, Roughness, and Discrete Defect
Characterization for Computer Disks, Wafers, and Flat
Panel Displays. International Society for Optical
Engineering (SPIE). Proceedings. Volume 2862. August
8-9, 1996, Denver, CO, Society of Photo-Optical
Instrument Engineers, WA, 104-118 pp, 1996.
Keywords:
differential mobility analyzer; electrical mobility;
light scattering intenstiy; microcontamination;
nomodisperse spheres; polystyrene latex spheres; real
world particles; wafer scanner; width of size
distribution; suspensions
Abstract:
In response to the semiconductor industry's need for
both smaller calibration particles and more accurately
sized larger particles, a joint SEMATECH, National
Institute of Standards and Technology, and VLSI
Standards, Inc. project was initiated to accurately
characterize 10 monodisperse polystyrene sphere
suspensions covering the particle diameter range from 70
to 900 nm. The sizing analyis is being performed by
electrical mobility analysis with a modified flow system
to enable the measurement of the width of narrow size
distributions. Results are presented on the mean size
and the width of the distribution for candidate samples
provided by five suppliers. The target sizes for the
first set of particles are 72 nm, 87 nm, 125 nm, and 180
nm. Challenges for detecting "real world" particles are
discussed including quantitative examples of the effects
of refractive index, layered structure, and
non-spherical shape on the light scattered by a
particle.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899