Channel count, masking, and compaction trade tester cost and diagnosis precision.
+------------------+----------------+----------------+----------------+
| Approach | Strength | Weakness | Best when |
+------------------+----------------+----------------+----------------+
| Conservative | safe | higher cost | ramp-sensitive |
| Balanced | practical | needs rigor | production |
| Aggressive | fast | escape risk | schedule pressure |
| Architecture | durable | slow | repeated pain |
+------------------+----------------+----------------+----------------+Tie approach to product risk and tester constraints
Optimizing one metric only
No regression ownership
DFT EVIDENCE MATRIX - Diagnosis & Yield Learning
+-------------------+------------------------+--------------------------+-------------------------+
| Evidence | Tells you | Does not prove | Next action |
+-------------------+------------------------+--------------------------+-------------------------+
| coverage report | fault detect trends | silicon root cause | inspect bucket details |
| pattern diff | generation changes | architecture quality | replay suspect patterns |
| timing/power report| test closure margin | diagnosis confidence | correlate fail logs |
| diagnosis summary | likely defect classes | ownership decision | assign action owner |
| signoff checklist | process completeness | correctness of evidence | peer review artifacts |
+-------------------+------------------------+--------------------------+-------------------------+Compression saves tester time only when diagnosis observability remains credible.
COMPRESSION LOOP
EDT/decompressor -> compressed patterns -> compactor responses -> diagnosisPATTERN vs COVERAGE
coverage up -> pattern count up
compression up -> pattern count down (until aliasing risk)compression ratio dashboard
pattern count trend
X-source report
diagnosis bucket summary
Compactor overflow plus unknown inflation caused false diagnosis; masking policy and channel map corrected.
Separate X issues from silicon defects
Replay failing patterns uncompressed
Track tester memory budget
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.
Fail logs and diagnosis map failing signatures back to likely defect sites, enabling systematic yield learning loops with design and process teams.
Metric: diagnosis resolution, top failing buckets, yield learning turnaround
This content block can't be displayed here.
Block type: unknown
This content block can't be displayed here.
Block type: unknown
This content block can't be displayed here.
Block type: unknown