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Physical DFT Debug: Step-by-Step Walkthrough

Step-by-Step Walkthrough for Physical DFT Debug.

Step-by-step analysis walkthrough

Use when you own Physical DFT Debug in a DFT closure review.

  1. Open release criteria and failing metric dashboard.

  2. Partition failures by pattern family and operating context.

  3. Inspect constraints, clocks, masks, and unknown handling.

  4. Check architecture assumptions against implementation reality.

  5. Review diagnosis evidence for repeatability.

  6. Assign owner and propose smallest high-confidence change.

  7. Run timing, power, and quality regressions.

  8. Capture final signoff or waiver decision.

Artifacts to collect

  • physical debug log, failing path snapshots, fix validation report

  • pattern tag manifest

  • tester program revision

  • signoff checklist

  • owner tracker

Decision memo template

diagram
DFT DECISION MEMO - Physical DFT Debug
scenario:
metric:
hypothesis:
fix:
regression:
owners: PD owner, STA owner, DFT owner

Reference visuals

Physical DFT flow

diagram
chain planning -> floorplan -> route/timing debug -> closure

DFT deep dive

Physical integration quality decides whether DFT architecture survives implementation realities.

Concept diagram

diagram
PHYSICAL DFT FLOW

chain planning -> floorplan placement -> route -> test timing/power validation

Metric graph

diagram
ROUTING BURDEN

poor chain order -> longer routes -> more hold buffers

Reports and artifacts

  • scan physical wirelength

  • congestion heatmap

  • test clock skew

  • handoff issue tracker

Mini case study

Late scan reorder reduced route detours and eliminated a major shift hold cluster before signoff.

Debug branches

  • Correlate chain order with congestion

  • Place compression logic near chain clusters

  • Keep DFT-PD handoff versioned

Senior review question

Ask: what evidence proves this DFT decision is safe for production?

Key takeaways

  • State metric, lot/corner context, and pattern tag with every claim.

  • Treat timing, power, and quality as one signoff problem.

Common pitfalls

  • Chasing coverage without legality checks.

  • Ignoring test-power side effects of pattern changes.

  • Debugging silicon without reproducible tags.

Principal DFT review addendum

Physical DFT debug traces violations to chain ordering, buffering strategy, clock topology, or extraction/view mismatches.

Metric: physical root-cause turnaround, repeat DFT route violations, signoff escape risk

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