Reticle defect inspection apparatus and reticle defect inspection method
View Patent ↗A reticle defect inspection apparatus that can carry out a defect inspection with high detection sensitivity are provided. The apparatus includes an optical system of transmitted illumination for irradiating one surface of a sample with a first inspection light, an optical system of reflected illumination for irradiating another surface of the sample with a second inspection light, and a detecting optical system that can simultaneously detect a transmitted light obtained by the first inspection light being passed through the sample and a reflected light obtained by the second inspection light being reflected by the sample. And the optical system of transmitted illumination includes a focusing lens driving mechanism for correcting a focal point shift of the transmitted light resulting from thickness of the sample.
1. A reticle defect inspection apparatus for inspecting for defects on a sample using a pattern image obtained by irradiating the sample on which patterns are formed with light, comprising:
a light source;
an optical system of transmitted illumination configured to irradiate one surface of the sample with a first inspection light;
an optical system of reflected illumination configured to irradiate another surface of the sample with a second inspection light;
a detecting optical system configured to simultaneously detect a transmitted light obtained by the first inspection light being transmitted through the sample and a reflected light obtained by the second inspection light being reflected by the sample;
a first imaging device configured to inspect the pattern image obtained by the transmitted light; and
a second imaging device configured to inspect the pattern image obtained by the reflected light, wherein
the optical system of transmitted illumination comprises a focusing lens being located on an optical path between the light source and the sample, and a focusing lens driving mechanism configured to correct a focal point shift of the transmitted light resulting from a thickness of the sample by moving the focusing lens.
2. The apparatus according to claim 1 , further comprising:
a reference pattern configured to correct a focal point shift of the transmitted light resulting from the thickness of the sample, the reference pattern being provided in the optical system of transmitted illumination, and the reference pattern being located on the optical path between the light source and the sample; and
a third imaging device configured to observe an image of the reference pattern.
3. The apparatus according to claim 2 , further comprising a correcting mechanism configured to make corrections using the focusing lens driving mechanism so that a maximum contrast of a reference pattern image obtained by imaging the reference pattern is achieved.
4. The apparatus according to claim 1 , further comprising a correcting mechanism configured to correct a focal point shift of the transmitted light using thickness information of the sample, which is measured in advance, and the focusing lens driving mechanism.