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TUG 2011 - Glenn Plowman, Staff Engineer, Qualcomm Adaptive Testing Techniques at Qualcomm, a Fabless Experience
Citation preview
Adaptive Testing Techniques at
Qualcomm, a Fabless Experience
Glenn Plowman
Qualcomm Inc.
glennp@qualcomm.com
Michael Schuldenfrei
OptimalTest
Michael.Schuldenfrei@optimaltest.com
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
Abstract
Adaptive testing techniques are becoming more and more popular as a
means to reduce cost of test.
This paper explores adaptive testing challenges and benefits at
Qualcomm.
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Executive Summary
Traditional methods of test time reduction are both volume and man
power intensive.
OptimalTest Adaptive TTR (ATTR) can help achieve TTR savings while
reducing manpower for TTR in high volume manufacturing.
Test programming and use of concurrency features must be reviewed
to avoid interference with ATTR.
Data collection, simulation and review processes must be put in place
to define ATTR rules.
Infrastructure is required to deliver, execute and monitor ATTR rules in
production.
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Overview
What is OT ATTR?
Benefits
Challenges
ATTR Rule Logistics: simulation, definition, deployment and execution.
Tester Integration
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
What is Adaptive Test?
•“Adaptive Test is a broad term used to describe methods that change
test conditions, test flow, test content and test limits (potentially at the
die/unit or sub-die level) based on manufacturing test data and statistical
data analysis.” (ITRS Definition)
Feed-forward data from in-line test
Feed-back data from post-test statistical analysis
Real-time & near real-time data analysis
Statistical Process Control (SPC)
Adjust test limits and content on-the-fly.
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
OptimalTest Adaptive TTR
OptimalTest has 2 Advanced Adaptive TTR (ATTR) methodologies
Parametric Method – performed on parametric tests while analyzing
& evaluating, in real-time, the process stability and making test time
reduction decisions
P/F Method – performed on low fallout tests
Leverage information from actual & historic device test results
Applicable at WS and FT
Selection is based on device & test characteristics and needs
Can be applied simultaneously or individually
No modifications required to existing test programs
Patents pending & issued
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
linked
reports
OPTIMALTEST
Database
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Overview
What is OT ATTR?
Benefits
Challenges
ATTR Rule Logistics: simulation, definition, deployment and execution.
Tester Integration
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Lower test costs – Reduce TTR manpower
Better Quality - Test sampling not
test removal
Achieved without changing
test programs
Benefits of Advanced Adaptive Test
9
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
Qualcomm TTR
• OT TTR Simulation reports help guide engineering to optimal and
automated TTR faster than engineers using manual techniques and
the results have a higher degree of statistical rigor.
Example: Half of the manual TTR savings obtained on a product
was attributed to information found in the simulation reports.
• OT is used to produce rules (recipes) for ATTR on testers with much
lower PTE time commitment.
Impact: EVEN AFTER manual TTR additional saving can be
obtained using ATTR rules with no loss to product quality.
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Overview
What is OT ATTR?
Benefits
Challenges
ATTR Rule Logistics: simulation, definition, deployment and execution.
Tester Integration
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
Challenges for ATTR –Deferred Calculation
Tests like DSP are farmed out to special processors that calculate
results in the background.
When test results are available the test record is generated with the
correct instance and test.
Test instance integrity is preserved but test order is not.
Deferred tests with low failure rates and high test times can be
TTRed.
The current TTR Simulator will be overly pessimistic (see COF).
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
Challenges for ATTR –Concurrent Test
Concurrent test is coming in IGXL 8.0.
Concurrent execution of instances will require novel solutions.
As of Jan 2011 Teradyne and OptimalTest are actively discussing
the topic of concurrent test.
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
Challenges for ATTR –Instance/Variable Dependencies
Setup Instances cannot be removed.
Instances that output information cannot be removed.
Instances that create any dependencies for following Instances must
not be removed (e.g. global variables).
TE must decide whether to support ATTR by minimizing inter-
instance dependencies during programming.
TE must identify instances which are not ATTR candidates due to
inter-instance dependencies during simulation.
Instances coded in VBT must also be included in the flow sheet.
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
Challenges – Continue on Fail
• Test 1 - Pass
• Test 2 - PassInstance A
• Test 3 – Fail => SBIN 1234, HBIN 4
• (TP stops here with Stop On Fail)Instance B
• Test 4 – Pass
• Test 5 – PassInstance C
• Test 6 – Fail
• Test 7 - FailInstance D
• Test 8 – Pass
• Test 9 - PassInstance E
Tests 6 & 7 each
have an
additional failure
if COF is used.
Fails for tests 6
& 7 are over-
reported.
TTR opportunity
for Instance D is
missed.
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Overview
What is OT ATTR?
Benefits
Challenges
ATTR Rule Logistics: simulation, definition, deployment and execution
Tester Integration
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Process Flow for Test Time Reduction
AnalysisHistorical Data
Test
Candidates
TTR RecipeAdaptive TTR
Rule
TTR Rule in
Real TimeTTR Results
OTPortal
17
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
ATTR Simulation at Qualcomm
Get TT Profile
Run Simulation
Review Results
Revise Test Candidates
Select TP
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
ATTR Rule Checkout at Qualcomm
Keith Barnes, Mike Campbell of Qualcomm, Pascal Ronde
Rule Editing and
Duplication
Correlation
Validation
PTE Review
Simulation Generated
Rule
Publish Correlation ATTR Rule
Publish Validation ATTR Rule
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
ATTR Rule Deployment
Qualcomm
Subcon 1
Publish Production
ATTR Rule
Rule Statuses
Datalogs w/ TTR
Feedback
Activate /Deactivate
Rule
Publish Validation
ATTR Rule
1 lot
Datalog w/ TTR
Feedback
Publish Production
ATTR Rule
Rule Statuses
Datalogs w/ TTR
Feedback
Subcon 2
ATTR Monitors
Publish Validation
ATTR Rule
2-3 lots
Datalog w/ TTR
Feedback
ATTR Monitors
Activate /Deactivate
Rule
Publish Correlation
ATTR Rule
The same rule may be deployed more quickly at additional subcons (e.g. Subcon 2)
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Overview
What is OT ATTR?
Benefits
Challenges
ATTR Rule Logistics: simulation, definition, deployment and execution.
Tester Integration
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
ATTR Rule Example
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
OptimalTest – Teradyne Interface for TTR
Before injection of Enable Words
After injection of Enable Words
23
Glenn Plowman: Qualcomm Inc.
Michael Schuldenfrei: Optimal Test
Executive Summary
Traditional methods of test time reduction are both volume and man power intensive.
OptimalTest Adaptive TTR (ATTR) can help achieve TTR savings while reducing manpower for TTR in high volume manufacturing.
Test programming and use of concurrency features must be reviewed to avoid interference with ATTR.
Data collection, simulation and review processes must be put in place to define ATTR rules.
Infrastructure is required to deliver, execute and monitor ATTR rules in production.
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