摘要 |
An exposure method is described, the method comprising the steps of a) transferring a first pattern onto each of a plurality of target portions of a substrate, the first pattern including at least one alignment mark; b) measuring a position of a plurality of alignment marks and determining an alignment mark displacement (dx, dy) for each of the plurality of alignment marks as a difference between a respective predetermined nominal position of the alignment mark and the respective measured position of the alignment mark; c) fitting a mathematical model to the plurality of alignment mark displacements to obtain a fitted mathematical model, d) determining a position of the first pattern in each of the plurality of target portions, based on the fitted mathematical model; e) transferring a second pattern onto each of the plurality of target portions, using the determined position of the first pattern in each of the plurality of target portions, wherein the mathematical model comprises polynomials Z1 and Z2: Z1 = r 2 cos(2θ) Z2 = r 2 sin(2θ) in polar coordinates (r, θ) or Z1 = x 2 - y Z 2= xy in Cartesian coordinates (x, y). |