A physical-location-aware X-filling method for IR-drop reduction in at-speed scan test

IR-drop problem during test mode exacerbates delay defects and results in false failures. In this paper, we take the X-filling approach to reduce IR-drop effect during at-speed test. The main difference between our approach and the previous X-filling methods [7]–[9] lies in two aspects. The first one is that we take the spatial information into consideration in our approach. The second one is how X-filling is performed. We propose a backward-propagation approach instead of a forward-propagation approach taken in previous work. The experimental results show that we have 42.81% reduction for the worst IR-drop and 45.71% reduction in the average IR-drop as compared to random fill method.