on-wafer probing best practices for power electronics...test system probing system discharge circuit...
TRANSCRIPT
On-Wafer Probing Best Practices for Power Electronics
Michael Lyman Market Development Manager August 2014 GSA Working Group
Agenda
Market drivers & trends MOSFET vs. IGBT device test & yield challenges Differing substrate materials Thinned/warped wafers & handling Arcing prevention for high-voltage testing Wafer interface options Chuck contact resistance minimization Safety (system, device, operator) Test-cell integration.
August 22, 2014
Power device production wafer-level test Much faster than individual package test
Save time and $ by not testing bad die
Save $$ by not packaging bad die
Identify process excursions real-time. Potential to save $$$!
Use to sort/bin while at the wafer level
Wafer–Level Test Advantages
August 22, 2014
Market Drivers & Trends
August 22, 2014
https://www.furukawa.co.jp/english/museum/floor3/04/10.htm
(USD 9.8B) (USD 3.9B) (USD 2.0B)
Time-to-Market Cost Customer quality demands (automotive, grid, etc.)
MOSFET vs. IGBT Device Test & Yield Challenges
Yield – MOSFET:
Relatively low-power Small die = many die on wafer Volume yield absorption Thorough & “easy” package test
– IGBT High-power Large die = few die on wafer Greater performance therefore test
sensitivity Greater yield sensitivity
August 22, 2014
Power Electronics Substrate Challenges
Si, GaN, GaN on Si(?), SiC
August 22, 2014
• 3yr: GaN $$ < Si • In production for low-voltage
applications now
High-End Solutions
Mid-Range Solutions
Low-End Solutions
600V 1,000V 1,800V+
Thinned & Warped Wafers
Some magic is required: – Handling – Vision – Vacuum/Cres/release
August 22, 2014
Arcing
Dft – Die size, pad distance, scribe line pathways,
passivation, neighbor die potential System
– System-level arcing prevention Design considerations Shielding Grounding
August 22, 2014
Wafer Interface
Probe-based – Fluid-based anti-arcing
Works, but messy on many levels
Probe-Card-based – Pressure-based anti-arcing
Pressure chamber covers entire DUT die and high electric field area
Increase pressure inside chamber, increase air breakdown voltage from DUT to adjacent dies
Additional pressure also decreases chuck/wafer resistivity
August 22, 2014
V= voltage d=distance a/b = environmental p= pressure
Paschen’s Law:
Air bearing
Air chamber
Chuck Interface Resistance
August 22, 2014
MicroVac™ High-Power Chuck 10.5 kV DC(coax mode), 400 A
(pulse) Typical is 5 mΩ resistance 500 vacuum holes with 100 - 300
µm diameter for thin-wafer handling down to ≤ 50 µm
Independently-controlled vacuum lines for 3”,4”,6” and 8” wafers; conventional and Taiko wafer support
Some more magic is needed…
Safety
Operator Safety Device Safety Integrated Test Cell
Safety
August 22, 2014
HV moduleSW
LV module
LV module
Test instrumentBreeder resistor
Discharge Switch
High voltage chuck
Test system Discharge circuitProbing system
< 5 msec discharge time
Applicable standards: – CAN/CSA C22.2 No 61010
- 1/R: 2009 – UL 61010 - 1/R: 2008-10 – EN 61010 - 1: 2001 – EN 61326:2006 – EN61000 - 3 - 3: 2008 – FCC 15.109(g): 2012 – CISPR 22:1997 Class A – FCC 15.107: 2012 Class A – SEMI S2 - 0703 – SEMI S8 - 0701
Die to die
Time
N+2th die
N+1th dieNth die N+4th
dieN+3th die
Test complete
Die sequence
ON Discharge
OFF
Dis
-cha
rge
Dis
-cha
rge
Dis
-cha
rge
Dis
-cha
rge
Dis
-cha
rge
Test Cell Integration
#1 request – it’s painful! – Somewhat “greenfield” application space & solutions
Complex & often unique interfaces – Cabling, connectors, etc. – Application-specific testers
Safety integration Test Executive
– Prober as Master or Slave? – Facility integration
Host, other databases, etc.
August 22, 2014
TESLA Product Family Overview (Blatant Advertising)
Power
150 mm 200 mm
300 mm
ENGINEERING Probes
APS200 TESLA
PRODUCTION
August 22, 2014
THANK YOU!
Additional questions, please contact: Michael Lyman [email protected] 503-601-1501
August 22, 2014
Extending system capabilities to 600 A / 10 kV
TESLA200 / 300 Update
• UHP probe for Ultra High Power capability
• New chucks with advanced current handling capability
Available June ‘14
August 22, 2014
Unique probe to allow testing High Voltage (10 kV) and High Current (300 A) all in one
Allows parallel configuration for 600 A
1 - 12 tines comb to address different pad sizes and test currents
Durable comb design for >100,000 touchdowns
Field replaceable comb
<2 mΩ low contact resistance, >10 TΩ insulation resistance
Ultra High Power Probe
August 22, 2014