This slides are introductory slides for the course testing and verification of VLSI Design which cover the basics of Why, Where, When and How of VLSI design testing
2. Acknowledgement…..
This presentation has been summarized from various
books, papers, websites and presentations on VLSI
Design and its various topics all over the world. I
couldn’t item-wise mention from where these large pull
of hints and work come. However, I’d like to thank all
professors and scientists who created such a good work
on this emerging field. Without those efforts in this very
emerging technology, these notes and slides can’t be
finished.
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3. Agenda
• Philosophy of Testing
• Why to test
• Do you love to be tested?
• Where do bugs come from?.
• When to test
• When should be your test scheduled?
• How to test
• Verification and Testing in context of VLSI
Design
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4. Murphy’s Law…….
- Edward Murphy, An American aerospace engineer who worked
on safety-critical systems
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25. • Intel, producer of the affected chip, claims that the
common user would experience it once every 27,000
years while IBM, manufacturer of a chip competing
with Intel's Pentium, claims that the common user
would experience it once every 24 days
• Loss of $475 million
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29. Defective Parts Per Million (DPPM)
• key metrics used to measure quality in many
semiconductor segments
• For mission-critical segments such as automotive and
medical
• Defective Parts Per Billion (DPPB)
• For a premium vehicle
• more than 7,000 semiconductor devices
• If you assume a DPPM rate of 1 for all the semiconductor
devices
• it equates to seven failures for every 1,000 cars
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30. • For Digital
• 100 to 1000 DPM
• For Analog and Mission Critical
• Zero DPM
• For 10nm Technology, 20% yield for many years for
Intel
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31. If testing is so important, why do people
not test it thoroughly?
• To save money
• To save time
• To hide the inefficiencies
• ….
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32. Tester…from Designer point of view…..
• The relationship between the tester and
everyone else in the project team has been like
….
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33. Why so love-hate relationship?
Can you prove the lion exists ?
Can you prove the ghost does exits ? Or does not
exist?
Testing can only show
the presence of errors,
never their absence.
-Edsger Djikstra
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34. Tester…..
From Production House point of view…..
“Bugfree Design”
does not give any extra revenue
but
bugs in design are very costly!!!!
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35. • Costly re-spin(s)
• Companies may miss out
market window
• Large companies can have
reputation at stake – e.g.
Pentium Bug
• Smaller companies can have
hard to recover financial
implications
• For start-ups, their existence
itself can be at stake!
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Respin….
65 % of chips fail at first silicon
Tester…..
From Production House point of view…..
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Tester…..
From User Point of View…..
Does user really value testing?
38. Even though…..
testing is important…..
•Does testing directly generate any
revenue?
•Does designer like testing?
•Does it generate “trust” ?
•Does trust generate “reusability”?
•Does reusability generate “revenue”?
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39. Why testing is of too much importance in
today’s semiconductor world…..
• In Earlier days, design had all the glamour and testing
was considered to be a dirty job, but now…
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[Courtesy: ITRS]
40. Testing and Verification in Current
Scenario
• While the silicon capacity continues to increase along the
Moore’s law, the efforts required to verify these designs have
increased even a greater rate : doubling roughly every six to
nine months.
• In the era of multimillion gate Asics, reusable IPs, and SoC
designs, 70% of the total efforts consumed by verification and
testing.
• Number of verification, validation, testing engineer is three
the number of RTL design engineer
• When design projects are completed, test benches makes up
80% of the total code volume.
• Most of the job openings in India is in this field.
• Design Hubs in Ahmedabad/Gujarat???
• Verification Hubs in Ahmedabad/Gujarat???
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42. Once they grow……
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Cost – Rule of 10
It costs 10 times more to test a device as we move to higher
level in the product manufacturing process
44. •Design Errors
• Misinterpretation of specification
•Fabrication Errors
• Wrong component
• Incorrect Wiring
•Fabrication Defects
• Imperfect Process Variations
•Physical Failure
• During life time of a system
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