초록 ▼

Particles are distinguished from pits, voids, scratches, and other subsurface defects in a surface of a substrate by impinging the defect with polarized light and integrating light scattered by the defect over a wide angular range to produce a total integrated response. Using a P-polarized incident

Particles are distinguished from pits, voids, scratches, and other subsurface defects in a surface of a substrate by impinging the defect with polarized light and integrating light scattered by the defect over a wide angular range to produce a total integrated response. Using a P-polarized incident light beam, particles are distinguished from subsurface defects by comparing the total integrated responses, which vary with changes in the incident angle. Alternatively, the defect is impinged with a P-polarized incident beam at a defined incident angle, and is then impinged with an S-polarized beam at the same incident angle. Total integrated responses are measured for both beams and a P-to-S ratio of the responses is calculated. Particles are distinguished from subsurface defects by comparing the P-to-S ratio to a predetermined threshold value which separates particles from subsurface defects.

대표청구항 ▼

[ What is claimed is:] [1.] A method for detecting a defect at a region on a surface of a substrate and for discriminating between particle defects and subsurface defects, the method comprising:directing a first beam of P-polarized light to impinge at said region on the surface at a first incident a

[ What is claimed is:] [1.] A method for detecting a defect at a region on a surface of a substrate and for discriminating between particle defects and subsurface defects, the method comprising:directing a first beam of P-polarized light to impinge at said region on the surface at a first incident angle;collecting scattered light caused by the first beam over a predetermined area and integrating the intensities of the scattered light over said area to form a first integrated response;directing a second beam of the P-polarized light to impinge at said region on the surface at a second incident angle which is greater than the first incident angle;collecting scattered light caused by the second beam over said area and integrating the intensities of the scattered light over said area to form a second integrated response; andcomparing the first and second integrated responses to determine whether a defect is a particle or a subsurface defect.