A practical approach to static signal electromigration analysis

Some literature suggests that sweep back effects may make electromigration (EM) a non-issue in signal lines. However this is only the case when the shape of the positive and negative current pulses are closely matched. Moreover, as performance pressures increase, the peak current values are exceeding the range for which electromigration models are valid. Thus, during the design of TI´s TMS320c6201 DSP chip, it was determined that limits needed to be placed on the current densities in signal-line segments, and that every net in the design should be checked. Dynamic current density analysis on all nets of a large design is computationally very expensive. In this paper, we describe a practical CAD methodology for a static, signal electromigration analysis for large cell-based designs. We present results and some observations from application of this methodology on the TMS320c6201.