摘要:
A method is provided for modifying an image of a pattern during a lithographic imaging process, where the pattern is arranged on a mask for imaging by a projection system on a surface, and the image is an image formed from the pattern by the projection system. In this method the imaging quality of the projection system is described by selected imaging quality parameters, and the image is adjustable by image adjustment parameters of the projection system. The method comprises the steps of determining an ideal image of the pattern, determining a simulated distorted image of the pattern based on the selected imaging quality parameters; determining a deviation between the simulated distorted image and the ideal image, and adapting the image adjustment parameters during the imaging process to minimize the deviation between the simulated distorted image and the ideal image on the basis of the selected imaging quality parameters.
摘要:
A mask pattern for imaging a marker structure on a substrate with a lithographic apparatus, the marker structure being configured to determine optical alignment or overlay, includes constituent parts to define the marker structure. The constituent parts include a plurality of segments, each segment having substantially a size of a device feature and a segment shape. The mask pattern includes at least one assist feature located at a critical part of the segment shape. The at least one assist feature has substantially a size below a resolution of the lithographic projection and is configured to counteract optical aberrations or optical limitations generated in the lithographic projection at the critical part.