A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Parallel High Throughput WLR Testing for Advanced Gate Dielectrics
P. Meyer
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Agenda
• Summary of new test challenges– Large sample size
– Highly dynamic degradation mechanisms
• Conventional system and NBTI• Conventional system and TDDB• New concept
– Improved NBTI testing
– Improved TDDB testing
– How it works
• Hybrid architecture• S510 and automated WLR test
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Reliability test challenges
• Higher throughput required– Need larger sample size for testing thinner oxide
• Minimizes error in Weibull distribution for thin oxide reliability test• Determines cross wafer variation due to increasing wafer size
– Due to the nature of reliability tests, parallel test is a must for statistical analysis and lifetime prediction
• New reliability issues = New test requirements– Minimize stress measure delay in NBTI test due to
degradation recovery when stress is off
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Increasing sampling size for thin oxide
• For thinner gate oxide, decreases, representing increasing randomness in device failure
• Statistical error increases with the same sample size for thinner oxide– Increase in sample size to
maintain statistical error
Rolf-Peter Vollertsen IRPS 2004 Tutorial
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
New test challenge: NBTI - Degradation Relaxation
• Device degradation may recover when stress is turned off
• Relaxation depends on temperature
• Device may reach 100% recovery at room temperature
• Degradation resumes after stress is reapplied
S. Rangan et al, IEDM 2003
Stress time (log)
1st stress
2nd Stress
% I
d d
egra
dat
ion
Stress OffRelaxation
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Time Dependent Relaxation
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
What tests do you run?
HCI/CHC TDDB EM NBTI/PBTI QBD BTS
Submit Clear
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Agenda
• Summary of new test challenges– Large sample size
– Highly dynamic degradation mechanisms
• Conventional system and NBTI• Conventional system and TDDB• New concept
– Improved NBTI testing
– Improved TDDB testing
– How it works
• Hybrid architecture• S510 and automated WLR test
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Conventional setup – stress, switch, and measure
WAFER
Switch Matrix
SMU1
Probe Card InterfaceProbeCard
SMU3
SMU2
SMUn
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Shared Stress SMU
SMU n
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
NBTI: The problem
stress
IV sweep
switch matrix Connection,
SMU assignment
stressswitch matrix Connection,
SMU assignment
Device relaxation
Minimize the device relaxation time
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Drawbacks of Conventional WLR Solutions
• Sequential device measuring
• Uncontrolled relaxation time: variable from device to device
• Test one structure at a time for meaningful NBTI measurement resultsTiming diagram for conventional WLR
multiplexed SMU solution performing NBTI
Switch SMU
2
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Agenda
• Summary of new test challenges– Large sample size
– Highly dynamic degradation mechanisms
• Conventional system and NBTI• Conventional system and TDDB• New concept
– Improved NBTI testing
– Improved TDDB testing
– How it works
• Hybrid architecture• S510 and automated WLR test
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
TDDB: Configuration 1
• Drawback– Voltage disruption during device breakdown
SM
U 1
SM
U 2
...
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
TDDB – Modified configuration 1
• Adding series resistors to eliminate stress voltage disturbance when one device breaks down
• Drawbacks – Effect of size of resistor on oxide breakdown to be examined– Time resolution depends on number of devices in parallel– Number of different stress conditions is limited to number of SMUs in system
SM
U 1
SM
U 2
...
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
TDDB: Configuration 2
• Advantages– Simple setup, easy to
implement
– Good time to breakdown accuracy
– Independent device control
• Drawback– Number of devices in
parallel is limited by cost, rack space, and instrumentation
SM
U 1
SM
U n
SM
U 4
SM
U 3
SM
U 2
...
...
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Conventional WLR Solution Fails to Monitor Leakage Current During Stress
Switch SMU
• Sequential device measuring
• Cannot continuously monitor devices during stress
• Misses soft breakdown events
• All devices must be placed under same stress conditionsTiming diagram for conventional WLR
multiplexed SMU solution performing TDDB
Initial MeasureInterval (pre-
characterization)
Final MeasureInterval (post-
characterization)
StressInterval
Vg-Ig
0 V
Vstress
Vgate 1
TimeMeasure Stress (infrequent readings)
Vg-Ig
0 V
Vstress
Vgate 2
VgatenVg-Ig
0 V
Vstress
Sw
itch
Sw
itch
Sw
itch
Sw
itch
Sw
itch
Sw
itch
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
What node is currently in technology development at your company?
Larger than 130nm 130nm 90nm 65nm
Submit Clear
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Agenda
• Summary of new test challenges– Large sample size
– Highly dynamic degradation mechanisms
• Conventional system and NBTI• Conventional system and TDDB• New concept
– Improved NBTI testing
– Improved TDDB testing
– How it works
• Hybrid architecture• S510 and automated WLR test
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
New Reliability Test Concept:SMU-per-Device
• Source-measure unit (SMU) per device provides:
• Device-independent stress conditions
• Precision measurement capability
• Simultaneous measurement
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Parallel SMU-per-Device Solution Controls Relaxation and Monitors During Stress
• Seamless transition between stress and measure cycles
• No uncontrolled relaxation time
• Continuous and independent device monitoring during stress
• Precise stress timing maximizes reliability modeling
Timing diagram for new SMU-per-device (pin) architecture performing NBTI
A
A
A
A
A
A
VST1 Measure Measure
VST2 Measure Measure
VSTN Measure Measure
Stress(with readings)
Stress(with readings)
Stress(with readings)
Vol
tage
app
lied
to D
UT
pin
TSTNa
TST2a
TST1a
Time
TST1b
TST2b
TSTNb
Stress(with readings)
Stress(with readings)
Stress(with readings)
Measure Stress (with readings)
Vgate1
Vgate2
VgateN
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Parallel SMU-per-device Solution Provides Independent Stress and Continuous Measurements During Stress
• Continuous measurements for maximum visibility into device failure
• Soft breakdown noise not compounded by devices SMU sharing
• Soft breakdown events always captured
• Independent stress conditions for every device
Timing diagram for new SMU-per-device (pin) architecture performing TDDB
DUTVstress
AIleak
DUTVstress
AIleak
DUTVstress
AIleak
Initial MeasureInterval (pre-
characterization)
Final MeasureInterval (post-
characterization)
Vg-Ig
0 V
StressInterval
Vstress
TimeMeasure Stress (with monitor)
Vgate1
Vg-Ig
0 V
Vstress
Vgate2
Vg-Ig
0 V
Vstress
VgateN
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
High Speed Parallel SMU Architecture
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Agenda
• Summary of new test challenges– Large sample size
– Highly dynamic degradation mechanisms
• Conventional system and NBTI• Conventional system and TDDB• New concept
– Improved NBTI testing
– Improved TDDB testing
– How it works
• Hybrid architecture• S510 and automated WLR test
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Combining High Speed Parallel with High Resolution SMUs
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
High Resolution and High Speed Parallel
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
What kind of reliability testing do you do now?
One structure/device at a time (serial) More than one structure/device at a time
(parallel) All structures in a site (parallel) Multi site (massively parallel)
Submit Clear
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Agenda
• Summary of new test challenges– Large sample size
– Highly dynamic degradation mechanisms
• Conventional system and NBTI• Conventional system and TDDB• New concept
– Improved NBTI testing
– Improved TDDB testing
– How it works
• Hybrid architecture• S510 and automated WLR test
A G R E A T E R M E A S U R E O F C O N F I D E N C E
a
www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
A new system…
• 4200-SCS - high resolution SMUs
• 4500-MTS - high speed parallel SMUs
• 707A - switch control• 7174A – low leakage switch
matrix• 7136 – bypass switch
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
S510 Software Capability
• KTE for automation– Complex sample plans– Standard output file format– Handles large quantities of data– Automatic wafer prober drivers
• Eases parallel test setup • Provides real time
NBTI/TDDB test monitoring• Provides either interactive
GUI or fully automatic operation
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
High Throughput and Flexibility for Wafer-Level Reliability Testing
• Dig out from ultra thin gate dielectric modeling backlog
• Accelerate reliability modeling with high throughput parallel automated testing
• Optimized for 65nm gate dielectric NBTI and TDDB reliability testing
• Scalable: Starting at 20 parallel source/measure channels
• Independent stress/measure channel for each structure
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
S510 is the Latest in a Continuum ofScalable WLR Solutions
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
Extending into the Fab with the S680
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
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• 001-440-248-0400 Outside the USA
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See www.keithley.com for additional worldwide offices
Via e-mail to [email protected]
Contact Keithley with Your Questions:
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www.keithley.comK E I T H L E Y C O N F I D E N T I A L – P R O P R I E T A R Y
© Copyright 2004 Keithley Instruments, Inc.
A Greater Measureof Confidence
