Patent ID: 7536660

Claim:
A computer-implemented method for estimating image intensity expected on a wafer when the wafer is exposed to an image of a reticle or mask, the method comprising: dividing, by a computer, layout data for the reticle or mask into windows, wherein each window includes one or more features; determining, by the computer, an estimate of image intensity associated with the area of the features in at least one respective window by: applying a decomposition algorithm to the features in the respective window to define primitives representative of the area; for each primitive, accessing area lookup tables, each storing pre-calculated data for a convolution of a sum of coherent systems (SOCS) kernel and the primitive; and using the data from the area lookup tables to determine the estimate of the image intensity associated with the area of the features in the respective window; determining, by the computer, an estimate of image intensity associated with the edges of the features in the at least one respective window by: applying a decomposition algorithm to the features in the respective window to define a number of edge segments; for each edge segment, accessing edge lookup tables, each storing pre-calculated data for a convolution of a SOCS kernel and the edge segment; and using the pre-calculated data from the edge lookup tables to determine the estimate of the image intensity associated with the edges of the features in the respective window; and combining the estimate of the image intensity associated with the area of the features with the estimate of the image intensity associated with the edges of the features to determine an overall estimate of image intensity in the at least one respective window.