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 method comprising:
irradiating one surface of a reticle with a first inspection light through an optical system of transmitted illumination, wherein the first inspection light is emitted from a light source;
irradiating another surface of the reticle with a second inspection light through an optical system of reflected illumination;
detecting, simultaneously and with a detecting optical system, a transmitted light obtained by the first inspection light being transmitted through the reticle and a reflected light obtained by the second inspection light being reflected by the reticle;
obtaining a first pattern image of the reticle by the transmitted light using a first imaging device;
obtaining a second pattern image of the reticle by the reflected light using a second imaging device; and
correcting a focal point shift of the transmitted light resulting from a thickness of the reticle by moving the focus lens in a direction of an optical axis of the first inspection light, wherein the focus lens is provided in the optical system of transmitted illumination, and the focus lens is located on an optical path between the light source and the reticle.
2. The method according to claim 1 , wherein
the correcting the focal point shift of the transmitted light includes focusing an image of a reference pattern provided in the optical system of transmitted illumination,
the reference pattern is located on an optical path between the light source and the reticle, and
the image of the reference pattern is obtained using a third imaging device.
3. The method according to claim 2 , wherein a transmission field stop is used as the reference pattern.
4. The method according to claim 3 , wherein the image of the reference pattern is focused by making adjustments to achieve a maximum contrast of the image of the reference pattern.
5. The method according to claim 2 , wherein the image of the reference pattern is focused by making adjustments to achieve a maximum contrast of the image of the reference pattern.