A method for timing constrained redundant via insertion

Abstract

Redundant via (RV) insertion is a useful mechanism to enhance via reliability. However, when extra vias are inserted into the design, the circuit timing might be changed. Therefore, how to insert RV under the timing constraints is the main challenge. In this paper, we introduce a new model to compute the distance between a RV and the corresponding single via, put forward a new RV type, which is called the long length via (LLV), and then present an improved RV insertion method considering the timing constraints. This computing model can certify that the timing, which is obtained after inserting a RV, is not greater than the original timing. Meanwhile, the new RV type LLV can increase the possibility of RV insertion; this method provides a global perspective for the RV insertion. Considering the timing constraints, the total redundant via insertion rate is 85.38% in the MIS-based method, while our proposed method can obtain a high insertion rate 88.79% for the tested circuits.