Improved Lithographic Accuracy Using Image Registration Technology

In order to improve lithographic accuracy, an image registration method based on spatial moments is suggested in this paper. First, match the reference image and the floating one using Fourier descriptors. This step is coarse matching. Second, locate edge accurately using spatial moments method and extract corner points. Finally, match the tow images according to the corner points extracted. This step is refine match. Experimental results show that accuracy of sub-pixel edge location can reach to 0.09 pixel and that of image registration can reach to 0.1 pixel.