Pattern inspection apparatus and method

1. A pattern inspection apparatus comprising:

a stage configured to mount thereon a target workpiece to be inspected where patterns are formed;

at least one sensor configured to move relatively to the stage and capture optical images of the target workpiece to be inspected;

a first comparing unit configured to compare first pixel data of an optical image captured by one of the at least one sensor with first reference data at a position corresponding to a position of the first pixel data; and

a second comparing unit configured to compare second pixel data of an optical image captured by one of the at least one sensor at a position shifted by a sub-pixel unit from the position where the optical image of the first pixel data is captured, with second reference data at a position corresponding to the position of the second pixel data.

2. The apparatus according to claim 1 , wherein when the optical image of the first pixel data and the optical image of the second pixel data are captured by one sensor, after the optical image of the first pixel data is captured, the one sensor is shifted in a second direction by a sub-pixel unit, and then, the optical image of the second pixel data is captured, and the one sensor includes a plurality of light receiving elements arrayed in the second direction orthogonal to a first direction to which the one sensor moves relatively to the stage.

3. The apparatus according to claim 1 , wherein when the optical image of the first pixel data and the optical image of the second pixel data are captured by a plurality of sensors, the optical image of the second pixel data is captured by one of the plurality of sensors which is different from one of the plurality of sensors having captured the optical image of the first pixel data.

4. The apparatus according to claim 1 , wherein the at least one sensor includes a plurality of light receiving elements arrayed in a second direction orthogonal to a first direction to which the at least one sensor moves relatively to the stage, and the first pixel data is acquired by one of the plurality of light receiving elements and the second pixel data is acquired by one of the plurality of light receiving elements arranged at a position which is different from a position where the first pixel data has been acquired.

5. The apparatus according to claim 4 , wherein when the optical image of the first pixel data and the optical image of the second pixel data are captured by one sensor, after the optical image of the first pixel data is captured, the one sensor is shifted in the second direction by a pixel unit and a sub-pixel unit, and then, the optical image of the second pixel data is captured.

6. The apparatus according to claim 1 , further comprising: a merge processing unit configured to merge a comparison result by the first comparing unit and a comparison result by the second comparing unit.

7. The apparatus according to claim 6 , wherein when the optical image of the first pixel data and the optical image of the second pixel data are captured by one sensor, after the optical image of the first pixel data is captured, the one sensor is shifted in a second direction by a sub-pixel unit, and then, the optical image of the second pixel data is captured, and the one sensor includes a plurality of light receiving elements arrayed in the second direction orthogonal to a first direction to which the one sensor moves relatively to the stage.

8. The apparatus according to claim 6 , wherein when the optical image of the first pixel data and the optical image of the second pixel data are captured by a plurality of sensors, the optical image of the second pixel data is captured by one of the plurality of sensors which is different from one of the plurality of sensors having captured the optical image of the first pixel data.

9. The apparatus according to claim 6 , wherein the at least one sensor includes a plurality of light receiving elements arrayed in a second direction orthogonal to a first direction to which the at least one sensor moves relatively to the stage, and the first pixel data is acquired by one of the plurality of light receiving elements and the second pixel data is acquired by one of the plurality of light receiving elements arranged at a position which is different from a position where the first pixel data has been acquired.

10. The apparatus according to claim 9 , wherein when the optical image of the first pixel data and the optical image of the second pixel data are captured by one sensor, after the optical image of the first pixel data is captured, the one sensor is shifted in the second direction by a pixel unit and a sub-pixel unit, and then, the optical image of the second pixel data is captured.

11. A pattern inspection method comprising:

capturing overlappingly optical images of a target workpiece to be inspected at positions shifted each other by a sub-pixel unit;

comparing first pixel data of an optical image which has been captured with first reference data at a position corresponding to a position of the first pixel data;

comparing second pixel data of an optical image captured at a position shifted by a sub-pixel unit from the position where the optical image of the first pixel data is captured, with second reference data at a position corresponding to the position of the second pixel data; and

outputting comparison results.

12. A pattern inspection method comprising:

capturing overlappingly optical images of a target workpiece to be inspected at positions shifted each other by a sub-pixel unit;

comparing first pixel data of an optical image which has been captured with first reference data at a position corresponding to a position of the first pixel data;

comparing second pixel data of an optical image captured at a position shifted by a sub-pixel unit from the position where the optical image of the first pixel data is captured, with second reference data at a position corresponding to the position of the second pixel data; and

merging comparison results and outputting a merged result.