Patent ID: 7002675

Claim:
A method for locating/sizing contaminants on a bare, highly polished, and planar surface of a dielectric or semiconductor material, comprising the steps of: focusing a coherent beam of diffraction limited monochromatic P-polarized light from a solid-state (no gas plasma involved) light source and directed specifically at Brewster's angle (principal angle) to form a quasi-elliptical illuminated spot on the material surface which specularly reflects a circular minimal power beam from the surface of the material the cross-section of which has a dark (no-light) central band and two outer low light lobes; causing a contaminant on the material surface to pass multiple times through the quasi-elliptical illuminated spot incident on the material surface so that the contaminant, on each pass through the illuminated spot, scatters the light in a quasi-hemispherical pattern; and disposing a high numerical aperture light collector, focused on the center of the quasi-elliptical illuminated spot, above and in close proximity to the material surface so as to redirect essentially all the light scattered (with effectively no secondary redirection) from the contaminant to a detector capable of converting the light collected to an electrical signal proportional to the light intensity.