Wafer Contamination and Defect Size Measurement Using Temporal Reflectance Variation From a Spatially Patterned Excitation
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18
A method of measuring the size of particles in a bare wafer scanner is provided whereby the wavelength of the incident light is used to determine an absolute length scale. Two plane waves are combined near the surface of wafer 11 to produce a sinusoidal interference pattern, thus producing nodes of spatially varying irradiance. The bare wafer behaves primarily as a mirror, except for the presence of particulates or other surface imperfections that scatter light in all directions. Some of the scattered light is received by the detector 12.