Adaptive Diagnosis Points for 100% Chain Diagnosis Coverage

A pre-silicon design-for-diagnosis flow is a critical step in IC manufacturing. It is the key to achieving high diagnosis quality, which is necessary to improve yield and meet time-to-volume business requirements. This paper introduces a novel mechanism that significantly enhances this process. By inserting an XOR gate at scan cells, we enable these cells to operate in an additional mode, thereby improving their diagnosability. The activation of this extra mode is facilitated by a combination of a diagnosis-enable signal bit and the scan-enable signal. A key aspect of our approach is using a local scan cell without an additional input pin to provide the diagnosis-enable signal, a practical innovation that enhances the efficiency of the manufacturing process.