| 摘要 |
The invention discloses a computer implemented method of fracturing a free form target design into elementary shots to get a minimum number of shots for a defined roughness of the contour. The method includes determining a first set of shots which pave the target design, except for gaps, and then determining a second set of shots to fill or cover the gaps. The dose levels of the overlapping shots in the first or second sets of shots are determined so that the compounded dose is adequate in view of the resist threshold, taking into account the proximity effect which affects the actual imprint of the shots on the insulated target. Advantageously, a dose geometry modulation is applied. Advantageously, rounded shot prints are produced by shots which are not circular. Shots and rounded shot prints may or may not overlap. The degree of overlap may be determined as a function of a desired optimization of a fit criteria between a printed contour and the contour of the desired pattern. Placements and dimensions of the shots may be determined by a plurality of fit criteria between said printed contour and said contour of the desired pattern. |
