Modeling Dynamic Parasitic Loading Effects on Scan Network Timing Margins
Dynamic parasitic extraction during ATPG shift prevents false timing violations by accounting for state-dependent capacitance and power rail collapses.
Structural Test Yield
Manufacturing Metric
Ratios comparing the number of units passing manufacturing defect screens to the total number of units processed indicate the health of the production line. A high structural test yield suggests that the fabrication and assembly processes are stable and that the design is robust against typical variations. This metric is used by production managers to identify trends and to trigger investigations into process shifts.
Yield Calculation
Data is collected from the automated test equipment at the end of the production line for each batch of components. To calculate structural test yield, the system counts the number of devices that pass all scan, memory, logic, and io tests. These results are then analyzed to determine the root causes of any failures, such as bridge defects, open circuits, or parametric variations.
This information is shared with the foundry to help optimize the manufacturing process and improve future yields. Statistical software processes these figures to detect subtle shifts in the production environment.
Operational Impact
Maintenance of a high yield is necessary to minimize the cost of production and to meet customer demand. When the structural test yield falls below a certain threshold, the production line may be halted to perform a detailed audit of the equipment and materials. This continuous monitoring ensures that only high-quality parts are shipped to customers while providing a clear picture of the manufacturing performance.