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In the past several years, DFM (design for manufacturability) is widely used in semiconductor process. DFM is to make layout design optimized for manufacturability's sake. Lithography friendly design (LFD) is one branch of DFM. To enhance process margin of photolithography, layout designers typically modify their layout design with the application of DFM or LFD tools. Despites those application, it is still not enough to realize enough process window as technology node goes to beyond 45nm. For these reasons, OPC (Optical proximity correction) engineers apply additional layout treatment prior to applying OPC. That is called as table-driven retarget, which is typically conducted by rule-based table. Similar to rule-based OPC, table-driven retarget also has limitations in its application.In this paper, we presented a model-based retargeting method to overcome the limitation of table-driven retarget. Once the criteria of process window has been set, we let OPC tool simulate the process window of each layout of design firstly. Then, if the output value of the simulated result cannot meet the preset criteria, OPC tool resizes the layout dimension automatically. OPC tool will do retarget-OPC-retarget iterations until process windows of all of designs become within the criteria. After all, the model-based retarget can guarantee accurate retarget and avoid over or under retarget in order to improve process window of full chip design.

In the process of optical proximity correction, layout edge or fragment is migrating to proper position in order to minimize edge placement error (EPE). During this fragment migration, several factors other than EPE can be also taken into account as a part of cost function for optimal fragment displacement. Several factors are devised in favor of OPC stability, which can accommodate room for high mask error enhancement factor (MEEF), lack of process window, catastrophic pattern failure such as pinch/bridge and improper fragmentation. As technology node becomes finer, there happens conflict between OPC accuracy and stability. Especially for metal layers, OPC has focused on the stability by loss of accurate OPC results. On this purpose, several techniques have been introduced, which are target smoothing, process window aware OPC, model-based retargeting and adaptive OPC. By utilizing those techniques, OPC enables more stabilized patterning, instead of realizing design target exactly on wafer.Inevitably, post-OPC layouts become more complicated because those techniques invoke additional edge, or fragments prior to correction or during OPC iteration. As a result, jogs of post OPC layer can be dramatically increased, which results in huge number of shot count after data fracturing. In other words, there is trade-off relationship between data complexity and various methods for OPC stability.In this paper, those relationships have been investigated with respect to several technology nodes. The mask shot count reduction is achieved by reducing the number of jogs with which EPE difference are within pre-specified value. The effect of jog smoothing on OPC output -in view of OPC performance and mask data preparation -was studied quantitatively for respective technology nodes.

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