Defect inspection apparatus and defect inspection method
An imaging portion acquires first sample-images of a first sample under optical-conditions, the first sample having a defect, and acquires second sample-images of a second sample under optical-conditions, the second sample having no defects. An arithmetic portion calculates a first difference between a first sample-image taken under a first optical-condition and the first sample-image taken under a second optical-condition, calculates a second difference between a second sample-image taken under the first optical-condition and a second sample-image taken under the second optical-condition, and selects the first and second optical-conditions under which a difference between the first and second differences becomes largest, as a first and a second inspection-condition. The imaging portion takes images of the target to be inspected under the first and second inspection-conditions to acquire a first and second inspection-images. The arithmetic portion performs inspection based on the difference between the first and second inspection-images.
1. A defect inspection apparatus comprising:
an illuminating portion emitting light to a pattern;
an imaging portion acquiring a plurality of first sample images by taking images of the pattern in a first sample under a plurality of optical conditions, the first sample having a defect in a first area of the pattern, and acquiring a plurality of second sample images by taking images of the pattern in a second sample under a plurality of optical conditions, the second sample having no defects in the first area of the pattern; and
an arithmetic portion calculating a first difference between a first sample image taken under a first optical condition and a first sample image taken under a second optical condition, among the plurality of optical conditions, calculating a second difference between a second sample image taken under the first optical condition and a second sample image taken under the second optical condition, and selecting the first and second optical conditions under which a difference between the first and second differences becomes largest, as a first and a second inspection condition,
wherein the imaging portion takes images of the pattern in a target to be inspected under the first and second inspection conditions to acquire a first and a second inspection image, and
the arithmetic portion determines whether there is a defect in the first area of the pattern in the target based on a difference between the first and second inspection images.
2. The defect inspection apparatus according to claim 1 , wherein the arithmetic portion determines that there is no defect in the first area if the difference between the first and second inspection images is smaller than a threshold value, whereas determines that there is a defect in the first area if the difference between the first and second inspection images is equal to or larger than the threshold value.
3. The defect inspection apparatus according to claim 2 , wherein the plurality of optical conditions are different from one another in any one of a wavelength of the light from the illuminating portion, polarization of the illuminating portion, an aperture of a lens provided to the illuminating portion, and an imaging plane location.
4. The defect inspection apparatus according to claim 2 , wherein the first and second optical conditions are different from each other in height of a stage on which the target to be inspected is placed.
5. The defect inspection apparatus according to claim 2 , wherein the first and second differences are calculated based on a brightness difference between the first and second sample images.
6. The defect inspection apparatus according to claim 1 , wherein the plurality of optical conditions are different from one another in any one of a wavelength of the light from the illuminating portion, polarization of the illuminating portion, an aperture of a lens provided to the illuminating portion, and an imaging plane location.
7. The defect inspection apparatus according to claim 1 , wherein the first and second optical conditions are different from each other in height of a stage on which the target to be inspected is placed.
8. The defect inspection apparatus according to claim 1 , wherein the first and second differences are calculated based on a brightness difference between the first and second sample images.
9. A defect inspection method using a defect inspection apparatus comprising an illuminating portion emitting light to a pattern, an imaging portion taking an image of the pattern, and an arithmetic portion inspecting a defect of the pattern, comprising:
acquiring a plurality of first sample images by taking images of the pattern in a first sample under a plurality of optical conditions, the first sample having a defect in a first area of the pattern;
acquiring a plurality of second sample images by taking images of the pattern in a second sample under a plurality of optical conditions, the second sample having no defects in the first area of the pattern;
calculating a first difference between a first sample image taken under a first optical condition and a first sample image taken under a second optical condition, among the plurality of optical conditions;
calculating a second difference between a second sample image taken under the first optical condition and a second sample image taken under the second optical condition;
selecting the first and second optical conditions under which a difference between the first and second differences becomes largest, as a first and a second inspection condition;
taking images of a location of the target to be inspected under the first and second inspection conditions to acquire a first and a second inspection image, and
determining whether there is a defect in the first area of the pattern in the target based on a difference between the first and second inspection images.
10. The defect inspection method according to claim 9 , wherein the arithmetic portion determines that there is no defect in the first area if the difference between the first and second inspection images is smaller than a threshold value, whereas determines that there is a defect in the first area if the difference between the first and second inspection images is equal to or larger than the threshold value.
11. The defect inspection method according to claim 10 , wherein the plurality of optical conditions are different from one another in any one of a wavelength of the light from the illuminating portion, polarization of the illuminating portion, an aperture of a lens provided to the illuminating portion, and an imaging plane location.
12. The defect inspection method according to claim 10 , wherein the first and second optical conditions are different from each other in height of a stage on which the target to be inspected is placed.
13. The defect inspection apparatus according to claim 9 , wherein the plurality of optical conditions are different from one another in any one of a wavelength of the light from the illuminating portion, polarization of the illuminating portion, an aperture of a lens provided to the illuminating portion, and an imaging plane location.
14. The defect inspection method according to claim 13 , wherein the first and second optical conditions are different from each other in height of a stage on which the target to be inspected is placed.
15. The defect inspection method according to claim 9 , wherein the first and second optical conditions are different from each other in height of a stage on which the target to be inspected is placed.
16. A semiconductor device manufacturing method using a defect inspection apparatus comprising an illuminating portion emitting light to a pattern formed with a mask on a semiconductor substrate, an imaging portion taking an image of the pattern, and an arithmetic portion inspecting a defect of the pattern, comprising:
acquiring a plurality of first sample images by taking images of the pattern in a first sample under a plurality of optical conditions, the first sample having a defect in a first area of the pattern;
acquiring a plurality of second sample images by taking images of the pattern in a second sample under a plurality of optical conditions, the second sample having no defects in the first area of the pattern;
calculating a first difference between a first sample image taken under a first optical condition and a first sample image taken under a second optical condition, among the plurality of optical conditions;
calculating a second difference between a second sample image taken under the first optical condition and a second sample image taken under the second optical condition;
selecting the first and second optical conditions under which a difference between the first and second differences becomes largest, as a first and a second inspection condition;
taking images of a location of the target to be inspected under the first and second inspection conditions to acquire a first and a second inspection image, and
determining whether there is a defect in the first area of the pattern in the target based on a difference between the first and second inspection images.