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22 March 2011 Evaluation of a new model of mask topography effects
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A new method capable of fast and accurate computation of mask topography effect was described and evaluated using a broad range of test structures. Results are presented for 1D and 2D test structures as well as for advanced OPC masks such as the one generated by inverse lithography or source-mask optimization software tools. The 1D test structures is a line and space test pattern with line width of 40nm, 60nm, 80nm, 100nm, 120nm the space width varying from 40nm to 1000nm. The RMS of the difference between the model and rigorous simulations is 3.6E-3 for 27,420 points correspond to all the combinations of line widths and space widths. The standard deviation of the CD difference between the model and the rigorous calculation, calculated for 5 thresholds (0.1, 0.11, 0.12, 0.13, and 0.14) and for all the structures, is 0.48nm. For a simple 2D test pattern, the mask fields are computed using rigorous calculation and compared to the model. The difference between the fields is within the error of the rigorous calculation. The resulting wafer images are almost identical with no re-scaling of the data was applied to either the mask fields or the wafer images. To study the applicability of the model to more complex patterns we have converted a contact level layout into an inverse mask and the new mask model was applied to the data in order to simulate the wafer image.
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Christophe Pierrat "Evaluation of a new model of mask topography effects", Proc. SPIE 7973, Optical Microlithography XXIV, 797317 (22 March 2011);


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