Accurate sizing of deposited PSL spheres from light scatter measurements

This paper reviews a light scatter technique used to size particle depositions of polystyrene latex spheres on silicon wafers. The technique has proved to provide accurate (approximately 1% uncertainty) sizing of PSL sphere depositions. Measurements were made of NIST Standard Reference Materials as a means of checking the technique and an uncertainty analysis was performed using the techniques prescribed by NIST. The technique has the advantage that measurements are made of PSL spheres depositions on a substrate, which is the way in which they are used to calibrate defect scanners. In addition to presenting the details of the sizing technique the paper also discusses implications for scanner calibration accuracy.