Bridging Fault is a defect model where two signal lines are unintentionally connected (shorted) — causing incorrect logic behavior by creating a wired-AND or wired-OR between the two signals, depending on the driving strengths.

What Is a Bridging Fault?

• Physical Cause: Metal particles, lithography defects, or over-etching creating a conductive bridge between two nets.
• Behavior:
• Dominant Driver: The stronger driver wins (wired logic).
• Feedback Bridges: Can create sequential behavior (latches) in combinational circuits.
• Detection: Requires patterns that drive the two bridged nets to opposite values.

Why It Matters

• Prevalence: Bridging faults account for a significant fraction of real manufacturing defects.
• Stuck-At Limitations: A stuck-at test set alone may miss ~15% of bridging faults.
• IDDQ Sensitivity: Bridging faults often cause elevated quiescent current, making IDDQ testing very effective.

Bridging Fault is the short circuit of logic — modeling the most common physical defect in modern dense interconnect metallization.