Diagnose compound scan chain and system logic defects

Scan based diagnosis can be of great help to guide physical failure analysis, which is critical for the success of silicon debug and yield ramp up. In practice, diagnosis becomes more difficult if scan chain defects and system logic defects co-exist on one die, which are called compound defects in this paper. We first describe the challenges in diagnosing this type of compound defects. A novel diagnosis flow is proposed to diagnose the compound defects on scan chain and system logic. The diagnosis methodology was successfully applied in industrial designs.