bridging fault

**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.