Test-Mode SDC turns DFT intent into measurable release confidence. Dedicated test SDC captures scan clocks, test enables, and exceptions needed to analyze shift and capture behavior correctly. The senior challenge is proving whether a metric move came from real quality gain, setup drift, or hidden regression.
When test SDC completeness, false test-path violations, test constraint audit score moves, can you identify mechanism, evidence quality, owner, and the minimum safe next action?
DFT CLOSURE FLOW - Test-Mode SDC
scan/test architecture
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v
ATPG constraints + fault models
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v
pattern generation + compression
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timing/power/physical validation
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v
silicon diagnosis and release signoff
Debug rule: always state metric, run tags, and owning team with any claim.Draw the causal flow before opening tools. Use these diagrams to anchor architecture, constraints, and silicon behavior discussions.
test clocks + test enables + mode exceptions
-> shift/capture timing checks
-> legal test closureDFT FLOW - Test-Mode SDC
scan insertion -> chain stitch -> compression map -> ATPG -> tester apply -> diagnosis
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controllability shift balance channel use coverage silicon correlation
Primary metric: test SDC completeness, false test-path violations, test constraint audit scoreDFT OWNERSHIP LAYERS - Test-Mode SDC
layer owns failure mode
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rtl/architecture scanability hooks uncontrollable logic
atpg/constraints legal pattern intent aborts, low coverage
physical/clocking chain route + test clocks shift hold/timing escapes
tester/program pattern apply integrity false binning / bad fails
quality signoff release criteria escapes or schedule slipPrimary metric: test SDC completeness, false test-path violations, test constraint audit score.
Primary artifact: test-mode SDC, constraint audit report, test path summary.
Owners to bring into review: STA owner, DFT owner, ATPG owner.
One failing signature and one reduced reproduction path.
Exact run tags for constraints, patterns, and tester program.
OWNERSHIP MAP - Test-Mode SDC
artifact owner
---------------- -----------------
architecture/report STA owner
constraints/setup DFT owner
physical/test ATPG owner
Name an owner for each failing metric cluster.Each topic includes mechanism, inputs/outputs, reports, debug, worked example, pitfalls, interview, checklist, theory, design space, expanded case study, walkthrough, comparison matrix, software view, and silicon impact.
State metric and run tags with every claim.
Connect every fix to a regression matrix.
Treat quality, timing, and power as coupled.
Coverage-centric decisions without legality checks.
Pattern changes without tester correlation.
Release calls without owner signoff.
Test signoff fails when shift/capture timing and test power are treated independently.
TEST SIGNOFF LOOP
test SDC -> shift/capture timing -> power-aware ATPG -> IR validation -> releaseTEST CURRENT
functional current baseline
scan shift current peak-risk zonetest-mode STA report
shift/capture split
test power IR map
waiver tracker
At-speed patterns passed timing but failed in production due to peak shift IR; staggered capture and power-aware fill resolved.
Tag test and functional corners separately
Check hold in shift mode
Correlate fail bins with power hotspots
Ask: what evidence proves this DFT decision is safe for production?
State metric, lot/corner context, and pattern tag with every claim.
Treat timing, power, and quality as one signoff problem.
Chasing coverage without legality checks.
Ignoring test-power side effects of pattern changes.
Debugging silicon without reproducible tags.