METHOD TO REMOVE AND COMPENSATE STATION-INDUCED ERROR PATTERN FROM MEASURED OBJECT CHARACTERISTICS

摘要

In the measurement of the surface of a wafer mounted on a mounting device, a method of removing the errors induced by the mounting device from the measurement data. The method includes the steps of 1) measuring a plurality of points on the surface to obtain a first matrix which contains the device induced errors and the proper surface of the object; 2) rotating the object independently of the mounting device; 3) measuring the rotated object to obtain a second matrix which contains the device induced errors and the proper surface of the objects as transformed by a rotation matrix; 4) obtaining the difference of the second matrix and the first matrix thereby eliminating the device induced error; and 5) applying the inverses of LU matrices on the difference of the rotation matrix and an identity matrix to obtain the proper surface. In step 5, the process involves flipping the wafer and measuring the surface as flipped.