High Power Probe Cards - COMPASScompass.formfactor.com/wp-content/uploads/High...T.I.P.S. Messtechnik GmbH. 2 High Power Probe Cards 1. Overview 2. ... • Limiting: Probe tip heating

High Power Probe Cards

for engineering and production test – A survey.

Speaker: Georg FRANZ

Co-author: Rainer GAGGL

T.I.P.S. Messtechnik GmbH

22

High Power Probe Cards

1. Overview

2. Power devices – Test requirements

3. High Voltage Probe Cards

4. High Temperature HV Probe Cards

5. High Current Probe Cards

6. Conclusion

33

Power devices – Test requirements

Power devices

• Applications

• Device types

• Rated Voltage

• Rated Current

image source: Tsunenobu Kimoto, Japanese Journal of Applied Physics 54, 040103, 2015

44


Typical 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

55


Typical engineering test requirements

6

6.2

6.4

6.6

6.8

7

7.2

7.4

7.6

7.8

8

-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.

66


Wafer 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

77


Typical power devices

• Diodes

• Mosfet

• IGBT

Example: IGBT

Collector

Emitter Gate

Emitter

CollectorGate

Passivation

Pad Metallization

Backside Metallization

88


High Voltage test – Flash-over risk

• Test voltage higher than insulation strength of ambient air

• High discharge current

• Device damage

C

E G E G

Floating (HV) GND

HV

6 kVDUT2 DUT1

Dicing frame

Reverse voltage test

99

High Voltage Probe Cards

Flash-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 f

lash

-ove

r [k

V]

p*d [bar mm]

Paschen law

1010


Flash-over suppression: principle

• Increase breakdown strength of air

• Local application of higher pressure

• Chip-scale pressure chamber

C

E G E G

Floating (HV) GND

HV

6 kVDUT2 DUT1

Compressed Air

1111


“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

1212


“Lupo” pressurized air chambermoveable „Lupo“ seal ring

1313


“Lupo” probe card in Tesla Prober

1414


“Lupo” contactless operation

1515

High Voltage Probe Cards“Lupo” contactless operation

1616

High Temperature HV Probe Crads

HV 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

1717


HT 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 contact

seal ring

1818


HT Engineering Probe Cards

• Non-hovering air chamber seal

• Large flat contact surface

• Seal still moveable

• Seal adjusts to probe wear/overtravel

Contact face

1919


HT 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

2020


HT Production Probe Cards

• production wafer sort

• hot wafer chuck 150°C

• hot compressed air 150°

• non-contact Lupo seal

2121


High 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

2222


Impact 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!

2323

High Current Probe Cards

High 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

2424


Challenges 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

2525


Probe current balancing 1

Electrical characteristics of"SmartClamp" module

"SmartClamp" module "SmartClamps“ integrated on probe card

2626


Probe current balancing 2

• For high pin counts / currents

• Resistors have value in range of CRES

Balancing resistors

R

R

R

R

R

R

R

R

R

R

2727

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

2828

Thank You!

For questions, please contact:

Georg FRANZ

T.I.P.S. Messtechnik GmbH

[email protected]

+43 4242 319 720 19

Documents

High Power Probe Cards - COMPASScompass.formfactor.com/wp-content/uploads/High...T.I.P.S. Messtechnik GmbH. 2 High Power Probe Cards 1. Overview 2. ... • Limiting: Probe tip heating