| 摘要 |
The invention relates to a method for producing a two-dimensional photomask. Said photomask comprises a plurality of transparent zones with one or more mask elements each that are disposed in such a manner that, when a target is exposed through the photomask, an exposure image is produced on the target, said image being adapted to a defined halftone image. The number, geometry and/or positions of the mask elements are determined by means of an evolutionary selection procedure that comprises a multitude of mutation steps. Starting from an initial distribution of mask elements a distribution of mask elements is successively produced, until a termination criterion is fulfilled, by using an operator that is selected from a group of statistical operators. For every actual distribution, the respective exposure image is determined that would result from the exposure of the target through a photomask with the actual distribution. The termination criterion is fulfilled when an approximative quality that is characteristic for the adaptation of the exposure image to the halftone image, reaches a threshold value or does not improve over a number of mutation steps. |
