Method for discriminating between holes in and particles on a film covering a substrate
AssigneeADE Corporation
InventorsJohn C. Stover, Yuri A. Eremin
Life of this patent
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Abstract
P-polarized light or having a strong P-polarized component is directed onto a filmed substrate at two (or more) different incidence angles, one angle being relatively large and the other angle being relatively small as measured from a surface normal. Light that is scattered into a back region of the hemispherical space above the substrate surface is collected and the intensity of the collected light is measured for each of the two incident angles. A defect can be classified as either a hole in the film or a particle on the film based on the relative intensities of the collected light.
Claims7
A method for detecting defects on a surface of a film-covered substrate and for discriminating between particles on the film and holes in the film, the method comprising:
- directing a first beam of light having a predominant P-polarized component onto the substrate at a first incident angle such that the light is scattered by any defect present at or in the film;
- detecting a first intensity of light back-scattered over one or more regions of space caused by the first beam;
- directing a second beam of light having a predominant P-polarized component onto the substrate at a second incident angle that is angularly displaced substantially farther from a surface normal than the first beam;
- detecting a second intensity of light back-scattered over said one or more regions caused by the second beam;
- and
- classifying a detected defect as either a particle on the film or a hole in the film based on relative magnitudes of the first and second intensities.
Dependencies are inferred from the claim text.