Model-Based Retarget for 45nm Node and Beyond

摘要

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.