Sample inspection system

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 beam of light to impinge at said region on the surface along a first path;
• collecting scattered light caused by the beam at a plurality of locations over a wide angular range and integrating the intensities of the scattered light from said locations to form a first integrated response;
• directing a beam of S-polarized light to impinge at said region on the surface along a second path;
• collecting scattered light caused by the S-polarized beam at said locations and integrating the intensities of the scattered light from said locations to form a second integrated response;
• and
• comparing the first and second integrated responses to determine whether a defect is a particle or a subsurface defect.

An apparatus for detecting a defect at a region on a surface of a substrate and for discriminating between particle defects and subsurface defects, the apparatus comprising:

• at least one light source operable to create a first beam of light and direct the first beam onto the region of the substrate surface at a first incident angle relative to a direction normal to the surface, and operable to create a second beam of P-polarized light and direct the second beam onto the region of the substrate surface at a second incident angle relative to a direction normal to the surface greater than the first incident angle;
• a collection system positioned above the substrate surface for receiving light scattered from the surface to a plurality of locations distributed over a range of angles above the substrate surface, the collection system being operable for integrating intensities of the scattered light over said plurality of locations to produce total integrated response signals corresponding to the first light beam and the second P-polarized light beam;
• and
• a processor in communication with the collection system and operable for comparing the total integrated response signal caused by the first light beam with the total integrated response signal caused by the second P-polarized light beam to determine whether a defect is a particle or a subsurface defect.