Patent ID: 7426011
Filing Date: 2008-09-16
Classification: G03F

Abstract:
1. A method of calibrating a lithographic projection apparatus having a projection system, the method comprising: printing a first set of test structures on a substrate, the substrate traveling a first course relative to the projection system to effect the printing of the first set of test structures; printing a second set of test structures on a substrate, the substrate traveling a second course relative to the projection system to effect the printing of the second set of test structures, the second course being different than the first course; measuring positional errors in the first set of test structures to obtain a first set of position error data; measuring positional errors in the second set of test structures to obtain a second set of position error data; calculating a third set of position error data from the first and second sets of position error data; and calibrating the lithographic projection apparatus using the third set of position error data.