Defect inspection apparatus
First Claim
1. A defect inspection apparatus comprising:
- a stage on which a plate to be inspected having a circuit pattern is mounted and which is movable in an X direction and in a Y direction perpendicular to the X direction;
a sensor which optically scans the circuit pattern to obtain scanned image data;
a scanned image data memory which stores the scanned image data in digital form;
a normal image data generator which generates normal image data expressed by use of multiple values based on computer-aided design data relating to the circuit pattern;
a reference data generator which corrects the normal image data to generate reference data, the reference data generator including a positional corrector which corrects a position data of the normal image data, a filtering part which subjects the normal image data to a filtering process, and a filter coefficient selector which has a plurality of sets of filter coefficients, selects one of the sets of filter coefficients and extracts a desired filter coefficient data used in the filtering part from the one selected from the plurality of filter coefficient sets; and
a comparator which compares the reference data with the scanned image data, wherein the filtering part comprises a first finite response filter having substantially symmetrical coefficients and a second finite response filter having a first-order lag function, the first and second finite response filters having respective transfer functions which are subjected to convolution.
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Abstract
A defect inspection apparatus includes a sensor which optically senses a circuit pattern formed on a plate to be inspected to obtain scanned image data thereof while moving relatively to the plate, an AD converter which converts the scanned image data into digital form, a normal image data generator which generates normal image data expressed by use of multiple values based on CAD data relating to the circuit pattern, a reference data generator which filters the normal image data to generate reference data while selecting filter coefficients according to the moving direction of the plate to be inspected by use of a finite response filter having asymmetrical coefficients, and a comparator which compares the reference data with the scanned image data.
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Citations
16 Claims
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1. A defect inspection apparatus comprising:
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a stage on which a plate to be inspected having a circuit pattern is mounted and which is movable in an X direction and in a Y direction perpendicular to the X direction;
a sensor which optically scans the circuit pattern to obtain scanned image data;
a scanned image data memory which stores the scanned image data in digital form;
a normal image data generator which generates normal image data expressed by use of multiple values based on computer-aided design data relating to the circuit pattern;
a reference data generator which corrects the normal image data to generate reference data, the reference data generator including a positional corrector which corrects a position data of the normal image data, a filtering part which subjects the normal image data to a filtering process, and a filter coefficient selector which has a plurality of sets of filter coefficients, selects one of the sets of filter coefficients and extracts a desired filter coefficient data used in the filtering part from the one selected from the plurality of filter coefficient sets; and
a comparator which compares the reference data with the scanned image data, wherein the filtering part comprises a first finite response filter having substantially symmetrical coefficients and a second finite response filter having a first-order lag function, the first and second finite response filters having respective transfer functions which are subjected to convolution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A defect inspection apparatus comprising:
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a sensor which optically senses a circuit pattern formed on a plate to be inspected to obtain scanned image data of the circuit pattern while moving relatively to the plate to be inspected;
an analog-to-digital converter which converts the scanned image data into digital form;
a normal image data generator which derives normal image data expressed by use of multiple values based on computer-aided design data relating to the circuit pattern;
a reference data generator which processes the normal image data to generate reference data while selecting filter coefficients according to a moving direction of the plate to be inspected by use of a finite response filter having asymmetrical coefficients; and
a comparator which compares the reference data with the scanned image data, wherein the finite response filter includes a first finite response filter having substantially symmetrical coefficients and a second finite response filter having a first-order lag function, the first and second finite response filters having respective transfer functions which are subjected to convolution. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification