Aerial image simulation.

A graphical user interface (GUI) including post-processing tools is necessary to achieve a user-friendly and task-oriented operation control. First steps have been realized by linking the aerial image simulator to the VISTA layout library [242] and integrating lithographically relevant functionality into the PIF editor [243,244]. Of great interest is the optimization of layouts with respect to optical proximity correction. By parameterizing the mask patterns such tasks could be readily done with the optimization package [245,246] available in the VISTA TCAD framework [243,247,248].

For optimization problems the run-time of the aerial image simulator is of crucial importance. By implementing acceleration techniques like Karhunen-Loève expansions [249, pp. 109-111] of the imaging kernel instead of Fourier expansions a considerable speed-up could be achieved [168]. Such expansions are better matched to the solution and thus fewer coefficients suffice for the same accuracy. In case of large area simulations the storage of the result on an equally spaced ortho-product-tensor-grid is very memory-intensive. An unstructured triangular grid keeps the memory demands small and makes the visualization faster. Especially for a sparse layout the storage would be reduced by several orders speeding up the whole simulator.