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US 2006/0233434 A1Published application
Method and apparatus for inspection
OwnerAkira Hamamatsu, Hisae Shibuya +1inventors
InventorsAkira Hamamatsu, Hisae Shibuya, Shunji Maeda
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Abstract
This invention relating to an inspection apparatus capable of classifying defects at high accuracy makes it possible to accurately extract various characteristic quantities of each defect by using the images obtained by imaging a semiconductor wafer under dark-field illumination, and providing, with respect to a differential image signal between the image signals obtained from dies near to each other in image brightness, a defect detection threshold and a characteristic quantity extraction threshold lower than the defect detection threshold.
Claims17
An inspection apparatus comprising:
- a stage system which mounts a target substrate with a plurality of dies arrayed thereon and moves at least in an XY direction;
- an illumination optical system which irradiates the substrate with illumination light;
- a detection optical system which acquires image signals by detecting reflected light obtained from the substrate;
- and
- an image processing unit which processes the image signals that have been acquired by the detection optical system;
- wherein the image processing unit further includes:
- a data storage adapted to store therein the image signals acquired by the detection optical system;
- a differential signal processing unit which obtains differential image signals by calculating differential between image signals obtained for each die in the image signals stored within the data storage;
- a threshold setting unit which sets a first threshold and a second threshold higher than the first threshold;
- a comparison unit which compares the differential image signals obtained from the differential signal processing unit, with each of the first threshold and second threshold set by the threshold setting unit so as to obtain defect image signals and defect data;
- a characteristic quantity extraction unit which extracts various characteristic quantities of defects based on the defect image signals obtained from the comparison unit, so as to obtain various characteristic quantity data of defects;
- and
- a defect classifying processing unit which classifies kind of defects, based on the various characteristic quantity data of defects obtained from the characteristic quantity extraction unit and the defect data obtained from the comparison unit.
10 more elements
An inspection apparatus comprising:
- a stage system which mounts a target substrate with a plurality of dies arrayed thereon and moves at least in an XY direction;
- an inspection conditions setting unit which sets a plurality of inspection conditions for controlling an irradiation angle and irradiation luminous quantity of illumination light onto the target substrate;
- an illumination optical system which irradiates the substrate with the illumination light under various inspection conditions set by the inspection conditions setting unit;
- a detection optical system which acquires image signals by detecting reflected light obtained from the substrate;
- and
- an image processing unit which processes the image signals that have been acquired by the detection optical system;
- wherein the image processing unit further includes:
- a data storage adapted to store therein the image signals acquired by the detection optical system for each of the inspection conditions;
- a comparative image process-processing unit including:
- a sort operation unit which the image signals stored within the data storage for each of the inspection conditions, rearranges the image signals obtained for each die, in order of brightness;
- and
- a differential signal processing unit which obtains a differential signal image for each of the inspection conditions by calculating differential between image signals of dies in which image brightness are near to each other, in image signals for each of dies rearranged for each of the inspection conditions by the sort operation unit;
- a threshold setting unit which sets for each of the inspection conditions a second threshold and a first threshold lower than the second threshold;
- a first comparison unit which compares the differential image signal obtained from the differential signal processing unit for each of the inspection conditions, with the first threshold set by the threshold setting unit for each of the inspection conditions, so as to obtain, for each of the inspection conditions, defect image signals exceeding the first threshold;
- a characteristic quantity extraction unit which extracts various characteristic quantities of defects based on the defect image signals obtained from the first comparison unit for each of the inspection conditions, so as to obtain various characteristic quantity data of defects;
- a second comparison unit which obtains defect data by comparing the differential image signal obtained from the differential signal processing unit for each of the inspection conditions, with the second threshold set by the threshold setting unit for each of the inspection conditions, so as to detect, for each of the inspection conditions, defects exceeding the second threshold;
- and
- a defect classifying processing unit which classifies kind of defects, based on the various characteristic quantity data of defects obtained for each of the inspection conditions from the characteristic quantity extraction unit and the defect data obtained for each of the inspection conditions from the second comparison unit.
15 more elements
An inspection method comprising the steps of:
- irradiating onto a target substrate with illumination light while moving a stage in one direction on which the target substrate with a plurality of dies arrayed thereon is mounted;
- acquiring image signals by detecting reflected light obtained from the substrate during the irradiation with the illumination light;
- and
- processing the acquired image signals;
- wherein the step of processing the image signals further includes the steps of:
- storing the acquired image signals;
- obtaining differential image signals by calculating differential between the images signals obtained for each die in the image signals stored by the storing step;
- setting a first threshold and a second threshold higher than the first threshold;
- comparing the differential image signals independently with each of the set first threshold and second threshold;
- and
- classifying kind of defects based on defect signals obtained in the comparing step by conducting the comparisons between the differential image signal and the first threshold and between the differential image signal and the second threshold.
8 more elements
Dependencies are inferred from the claim text.