ATPG Constraints: Review Checklist

Review checklist

Review Checklist for ATPG Constraints focuses on constraint consistency errors, illegal state count, pattern abort rate. The goal is to convert metric movement into mechanism, owner, and release decision.

• Run tags and scenario context are explicit.

• Constraints and legality assumptions are documented.

• Quality, timing, and test-power checks are included.

• Diagnosis evidence supports residual-risk decision.

• Owners signed: ATPG owner, RTL owner, DFT owner.

Signoff ownership

OWNERSHIP MAP - ATPG Constraints

artifact              owner
----------------      -----------------
architecture/report ATPG owner
constraints/setup   RTL owner
physical/test       DFT owner

Name an owner for each failing metric cluster.

DFT deep dive

ATPG quality comes from fault model choice plus legal constraints, not raw pattern volume alone.

Concept diagram

ATPG FLOW

fault model -> constraints -> generation -> simulation -> coverage closure -> signoff

Metric graph

COVERAGE GAP

target coverage
  ^
  |      o before closure
  |          o after fixes
  +---------------------> iteration

Reports and artifacts

• fault model coverage

• untestable class report

• constraint legality errors

• pattern signoff memo

Mini case study

Transition coverage stalled due to clock constraints mismatch; updated at-speed capture definitions recovered target.

Debug branches

• Classify untestable faults

• Diff ATPG constraints each run

• Pair coverage with pattern budget

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

ATPG constraints encode legal test-mode behavior, clocks, resets, and masks so generated patterns are both executable and meaningful.

Metric: constraint consistency errors, illegal state count, pattern abort rate