Model-Based Insertion of Assist Features Using Pixel Inverstion Method: Implementation in 65nm Node
Sub-resolution assist feature (SRAF) is widely used to improve lithographic performance. Rule-based SRAF insertion has been working well for one dimensional cases but becomes quite complex for 2-dimentional arbitrary layout. In addition, the best rule generation involves a large amount of simulation and empirical data collection. Therefore model-based SRAF insertion is much more desirable especially for 65nm node and below. In this work we use the newly developed pixel inversion method for a true model-based SRAF insertion. We’ll extend our work from contact layer to lines and spaces layer to demonstrate the capability of this method for all critical layers of 65nm node. This method will be used in combination with model-based OPC to achieve the required overlapping process window and CD control. Furthermore, the manufacture issues such as mask making time and mask inspection will be examined and reported.
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