Application of modified Jog-fill DRC rule on LFD OPC flow

摘要

The methodology of lithography friendly design (LFD) has been widely adopted since it dramatically reduces cycle of design revision as well as number of learning cycles to reach acceptable yield. LFD is, for example, the reduction number of small jogs and notches in original, pre-OPC layouts. We can call them as OPC-unfriendly patterns since they create unnecessarily complicated OPC patterns. They usually meet design rule so that DRC does not detect or screen them out. Also, they make many errors after OPC because OPC model recognizes just as one of small features that it should care. This generates many false alarms at OPC verification and mask rule check. General approach to implement LFD is to update rule table or design rule by taking actual yield and failure analysis data into consideration of database handling flow. Another method is the utilization of simulation to predict lithography unfriendly designs. It takes time to setup excellent rule for accurate prediction even if they are very good approach as fundamental solution for LFD. It will be better to have a simple solution with fast setup and improvement on major lithography unfriendly designs such as small jogs and notches. In this paper, we proposed new type of LFD flow which is the application of modified DRC step on LFD flow. This modified DRC identifies OPC-unfriendly patterns, and changes to "OPC-friendly" as well as fixing design rule violations. It is a pre-OPC layout treatment to remove small jogs and notches. After finding small jogs or notches, DRC software removes jogs and notches. In this case, unnecessary OPC fragments could be avoided. Using this jog-fill technique, we can dramatically reduce the incidence of necking or bridging, improve contact coverage, and, as a result, it enhances the final yield and reliability of circuit.