Patent ID: 7224437

Claim:
A method for characterizing an illumination pupil of an exposure tool, comprising: processing a plurality of pinhole test patterns formed at a plurality of test site locations to facilitate locating edges; and extracting illumination pupil characteristics in response to locating contour edges during said step of processing; wherein said step of processing includes: printing individual test patterns at said plurality of test site locations; wherein said step of printing includes: changing dose and defocus conditions at each individual one of said plurality of test site locations to obtain a focus exposure matrix; wherein said step of extracting includes: sampling edge contour points; and aligning the sampled edge contour points with respect to each other; obtaining a weighted summation of aerial image values at each sampled edge contour point over an illumination pupil plane; and using a predefined formula to extract the illumination pupil characteristics; and wherein said predefined formula is: D 0 D ij ⁢ = LSQ ⁢ ∑ x , y ⁢ Δ ⁢ ⁢ k x ⁢ Δ ⁢ ⁢ k y ⁢ I ⁡ ( k x , k y ) ⁢  U ⁡ ( x ijk , y ijk , z ij ; k x , k y )  2 I(k x ,k y )≧0 where D 0 is a dose to clear, D ij is a dose value for corresponding x ijk and y ijk sampled edge contour points, z ij is a defocus value for corresponding x ijk and y ijk sampled edge contour points, k x and k y are illumination pupil plane coordinates, and I is a value of the illumination pupil intensity at the points k x and k y .