APPARATUS AND METHOD FOR MEASURING THE POSITIONS OF MARKS ON A MASK

摘要

An apparatus (1 ) for measuring the positions of marks (M) on a mask (2) is provided, said apparatus comprising a mask holder (3) for holding the mask (2), a recording unit (7) for recording the marks (M) of the mask (2) held by the mask holder (3), an actuating module (12) for moving the mask holder (3) and the recording unit (7) relative to each other, and an evaluating module (17), which numerically calculates the gravity-induced sagging of the mask (2) in the mask holder (3) and determines the positions of the marks (M) on the mask (2), based on the calculated sagging, the recordings made by the recording unit (7) and the relative movement between the mask holder (3) and the recording unit (7), wherein, prior to calculating said sagging, the present position of the mask (2) in the mask holder (3) is determined and is taken into consideration in said numerical calculation, and/or the geometrical dimensions of the mask (2) are taken into consideration in said numerical calculation of sagging.