Hierarchical optical proximity correction on contact hole layers

As the size of contact holes shrinks below 0.2 /spl mu/m, optical proximity correction (OPC) on contact hole layers becomes essential. When correcting contact holes, 1-dimensional correction is not applicable, and 2-dimensional correction is required, which needs much more intensive computation. To reduce computation, it is very effective to take advantage of the hierarchy of the input data. In order to further accelerate the OPC calculation, we adopted pattern matching into the OPC system, which can extract the hierarchy implicit in the layout data.