Reduction of layout complexity for shorter mask writetime
As tolerance requirements for the lithography process continue to shrink, the complexity of the optical proximity correction is growing. Smaller correction grids, smaller fragment lengths and the introduction of pixel-based simulation lead to highly fragmented data fueling the trend of larger file sizes as well as increasing the writing times of the vector shaped beam systems commonly used for making advanced photomasks. This paper will introduce an approach of layout modifications to simplify the data considering both fracturing and mask writing constraints in order to make it more suitable for these processes. The trade-offs between these simplifications and OPC accuracy will be investigated. A data processing methodology that allows preserving the OPC accuracy and modifications all the way to the mask manufacturing will also be described. This study focuses on 65nm and 45nm designs.
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