High Power Probe Cardsfor engineering and production test – A survey.
Speaker: Georg FRANZCo-author: Rainer GAGGL
T.I.P.S. Messtechnik GmbH
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High Power Probe Cards1. Overview
2. Power devices – Test requirements
3. High Voltage Probe Cards
4. High Temperature HV Probe Cards
5. High Current Probe Cards
6. Conclusion
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Power devices – Test requirementsPower devices
• Applications
• Device types
• Rated Voltage
• Rated Current
image source: Tsunenobu Kimoto, Japanese Journal of Applied Physics 54, 040103, 2015
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Power devices – Test requirementsTypical production test requirements
• Reverse Voltage (Breakdown Voltage) -> Up to several kV
• Forward Current (On-state resistance) -> Up to several kA
• Reverse Current (Leakage Current at high reverse voltage)
• Dynamic switch test (max power dissipation) -> Up to several kA / kV
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Power devices – Test requirementsTypical engineering test requirements
66,26,46,66,8
77,27,47,67,8
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-50 -25 0 25 50 75 100 125
UR
[kV]
Temperature [°C]
Reverse current IR for IGBTs with different termination structures as a function of temperature – at different Reverse voltages.
Reverse Voltage UR as a function of temperature.
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Power devices – Test requirementsWafer Tests
• Production: Reverse Voltage -> High Voltage
• Production: Reverse Current -> High Voltage
• Production: Forward Current -> High Current
• Production: Dynamic Switch -> High Current & High Voltage
• Engineering: Reverse Voltage -> High Voltage & High Temperature
• Engineering: Reverse Current -> High Voltage & High Temperature
• Engineering: Dynamic Switch -> High Current & High Voltage & High Temperature
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Power devices – Test requirementsTypical power devices
• Diodes
• Mosfet
• IGBT
Example: IGBT
Collector
Emitter Gate
Emitter
CollectorGate
Passivation
Pad Metallization
Backside Metallization
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Power devices – Test requirements
C
E G E G
Floating (HV) GND
HV
6 kVDUT2 DUT1
High Voltage test – Flash-over risk
• Test voltage higher than insulation strength of ambient air
• High discharge current
• Device damage
Dicing frame
Reverse voltage test
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High Voltage Probe CardsFlash-over suppression: theory
• Empirical Paschen law
• For breakdown strength of air
• breakdown voltage increases with pressure
• Higher pressure -> higher test voltage
-> Safe test voltage rises appr. linearly with pressure!
0,1
1
10
100
0,001 0,01 0,1 1 10 100
U fl
ash-
over
[kV]
p*d [bar mm]
Paschen law
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High Voltage Probe Cards
C
E G E G
Floating (HV) GND
HV
6 kVDUT2 DUT1
Flash-over suppression: principle
• Increase breakdown strength of air
• Local application of higher pressure
• Chip-scale pressure chamber
Compressed Air
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High Voltage Probe Cards“Lupo” pressurized air chamber design
• Non-contact seal
• Seal hovers above wafer
• Compressed Air expands in gap
• Air exhausts through gap
• Pressure constant over chamber
moveable „Lupo“ seal ring
gap ~ 80micron
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High Voltage Probe Cards“Lupo” pressurized air chamber
moveable „Lupo“ seal ring
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High Voltage Probe Cards“Lupo” probe card in Tesla Prober
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High Voltage Probe Cards“Lupo” contactless operation
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High Voltage Probe Cards“Lupo” contactless operation
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High Temperature HV Probe CradsHV Wafer probing at higher temperatures
• Hot chuck 150°C
• TIPS Lupo air chamber
• Cooling effect on wafer
• Local cooling can disturbChuck temperature control
compressed air
hot chuck
probe needles
wafer
pressure chamber
gap ~ 80 micron
PCBmovable side wall
Strong local cooling !!
150°C
25°C
moveable „Lupo“ seal ring
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High Temperature HV Probe CradsHT Engineering Probe Cards
• device characterizationand development
• hot wafer chuck 150°C
• compressed air 25°
• Contact Lupo seal :-> low air flow-> low cooling
compressed air
hot chuck
probe needles
wafer
pressure chamber
PCB
no gap,leaking air
Almost no cooling!
150°C
25°C
moveable contactseal ring
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High Temperature HV Probe CradsHT Engineering Probe Cards
• Non-hovering air chamber seal
• Large flat contact surface
• Seal still moveable
• Seal adjusts to probe wear/overtravel
Contact face
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High Temperature HV Probe CradsHT Production Probe Cards
• Hot compressed air supply
• dual hot-cold air streamto protect probe card
• reduced breakdown strengthat higher temperatures
hot compressed air inlet
hot chuck
probe needles
wafer
pressure chamber
gap ~ 80 micron
PCB moveable Lupo seal ring
cold airflow
hot airflow
150°C
150°C
25°C
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High Temperature HV Probe CradsHT Production Probe Cards
• production wafer sort
• hot wafer chuck 150°C
• hot compressed air 150°
• non-contact Lupo seal
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High Temperature HV Probe CradsHigh Temperature Pressurized Air Supply
• Electrical heater
• Heats cold compressed air to 150°C
• closed-loop temperature control
• temperature sensor in probe card
• fast settling, stable operation
• integrated air cooling for probe card
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High Temperature HV Probe CradsImpact of Temperature on Breakdown Voltage
• Breakdown strength (Paschen law) for 25°C
• Hot air has lower density-> pressure must be increased to get same
breakdown strength-> compensation factor is ratio of absolute
temperatures
At 150°C -> 33% higher pressure needed!
• Hot air stream: blows up to 600 W into proberprober thermal management!
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High Current Probe CardsHigh current test
• Forward current test
• Up to 1200 Ampere on a single die!
• Pulsed currents 5A/probe for 200µs
• Limiting: Probe tip heating
• Copper-Beryllium probes
IGBT, 1200 Ampere, 250 probes
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High Current Probe CardsChallenges in high current testing
• Strong probe tip heating
• Heating depends on CRES
• Non-uniform current distribution
• Probe / tip overheating
• Pad melting!current per probe
melting limit
source
CRES per probe
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High Current Probe CardsProbe current balancing 1
Electrical characteristics of"SmartClamp" module
"SmartClamp" module "SmartClamps“ integrated on probe card
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High Current Probe CardsProbe current balancing 2
• For high pin counts / currents
• Resistors have value in range of CRES
Balancing resistors
RR
RR
RR
RR
RR
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Conclusion
• High power testing is feasible, limits pushed to 10kV / 1000A and beyond
• Trend to ever higher temperatures (125…150…175…200°C)
• Trend to production wafer sort at high temperatures-> hot air testing is feasible but very costly
• Full coverage of test requirements is difficult to achieve, especially at higher temperatures
-> physics are imposing the limits
• We recommend to use “engineering” probe cards for highest temperature / voltage requirements
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Thank You!
For questions, please contact:Georg FRANZ
T.I.P.S. Messtechnik [email protected]
+43 4242 319 720 19
High Power Probe Cards�for engineering and production test – A survey.High Power Probe CardsPower devices – Test requirementsPower devices – Test requirementsPower devices – Test requirementsPower devices – Test requirementsPower devices – Test requirementsPower devices – Test requirementsHigh Voltage Probe CardsHigh Voltage Probe CardsHigh Voltage Probe CardsHigh Voltage Probe CardsHigh Voltage Probe CardsHigh Voltage Probe CardsHigh Voltage Probe CardsHigh Temperature HV Probe CradsHigh Temperature HV Probe CradsHigh Temperature HV Probe CradsHigh Temperature HV Probe CradsHigh Temperature HV Probe CradsHigh Temperature HV Probe CradsHigh Temperature HV Probe CradsHigh Current Probe CardsHigh Current Probe CardsHigh Current Probe CardsHigh Current Probe CardsConclusionThank You!