APPARATUS AMD METHOD FOR MASK METROLOGY

摘要

There is provided a mask metrology apparatus (1) comprising: a mask holder (2) for holding a mask (3) having an object plane with a plurality of marks (4), a mask positioning device (5) for positioning the mask holder in a predetermined position, measurement optics (6) for measuring the position of the marks (4) of the mask (3) held by the mask holder (2), wherein the mask holder (2) holds the mask (3) with the object plane substantially parallel to the direction of gravity and supports the mask (3) along a horizontal edge (13, 35) of the mask (3) with a uniformly distributed force against gravity.