Cell-Aware Scan Diagnosis Using Partially Synchronous Set and Reset

Many defects affecting the inside of the cells cannot be identified, limiting yield improvement. To overcome the limit, cell-aware diagnosis has been introduced, but it is rarely used in the scan chain domain due to the characteristics of a scan cell. The design of the scan cell is complex, but there are few I/O pins to control and observe. In this paper, the scan cell design is modified, and partially synchronous set and reset are used. In the proposed design, during the set/reset operation, some regions of the design are isolated and not propagated to any output. Thus, a large amount of equivalent defects in the regions will be excluded from the diagnosis process, increasing the performance, and reducing the cost of the diagnosis.