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Selection of Calibration Particles for Scanning Surface Inspection Systems.


pdf icon 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.