SiC @ Infineon - Freephilippe.perdu.free.fr/workshops/workshop2012/SmartFA/pdf/3 - FA... · etching...
Transcript of SiC @ Infineon - Freephilippe.perdu.free.fr/workshops/workshop2012/SmartFA/pdf/3 - FA... · etching...
SiC @ Infineon
An insight in the analysis for SiC
André KabakowInfineon Technologies [email protected]
Copyright © Infineon Technologies 2011. All rights reserved.
Content
General information
Examples of analysis
6/19/2013 Page 2
Summary and Outlook
Copyright © Infineon Technologies 2011. All rights reserved.
Content
General information
Examples of analysis
6/19/2013 Page 3
Summary and Outlook
Copyright © Infineon Technologies 2011. All rights reserved.
Purpose
Infineon is one of the key player in SiC power technology.
Understanding the material is essential to keep this role.
SiC is about 30 years behind Si (taking wafer size as a basis ). SiC is about 30 years behind Si (taking wafer size as a basis ).
fundamental research is still ongoing
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Material properties
very hard
high temperature stability
high thermal conductivity
excellent chemical and radiation resistance
more than 250 known polytypes
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more than 250 known polytypes
most common structures: 6H, 4H and 3C
only 4H SiC used for IFX power devices
100 mm (4-inch) wafers available today
150 mm wafers available since August 2012
4H structure - ABCB
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Physical and electrical properties
wide energy bandgap (eV)
4H-SiC: 3.26 Si: 1.12
high breakdown electric field [V/cm]
4H-SiC: 2.2 x 106 Si: 2.5 x 105
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high thermal conductivity (W/cm · K @ RT)
4H-SiC: 3.0-3.8 Si: 1.5
high saturated electron drift velocity [cm/sec (@ E ≥ 2 x 105 V/cm)]
4H-SiC: 2.0 x 107 Si: 1.0 x 107
SiC is very suitable for power devices
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SiC market and potential
SiC power technology has the potential tostart to play a major role next to conventionalSi in the current decade
estimated worldwide annual sales 100-150 Mio. €
estimated growth rate 30-40% p.a.
key applications
hybrid and electric vehicles
renewable energies (wind energy plants and solarconverter)
switching power supplies
uninterruptable power supplies
drives
key drivers
efficiency
low system costs
power density
6/19/2013 Page 7Copyright © Infineon Technologies 2011. All rights reserved.
SiC related issues
defect density (104-105 cm-2) affects the performance andreliability of SiC devices
influence of crystal defects on functionality and reliability ofSiC devices is barely understood
characterization and analysis necessary to develop failure
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characterization and analysis necessary to develop failuremechanisms
formation of a MOS structure not as easy as for Si
new challenges for FA
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Content
General information
Examples of analysis
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Summary and Outlook
Copyright © Infineon Technologies 2011. All rights reserved.
in principle as for Si power devices
high current measurements
High Power Curve Tracer (pulsed measurement)
¬ avoids overheating of the device
partial backside opening of the device for
Electrical characterization
partial backside opening of the device forfurther characterization
¬ BS contact with probe needle not necessary
¬ ensures a good BS contact
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package
leadframe
solder
die
Copyright © Infineon Technologies 2011. All rights reserved.
Emission Microscopy - EMMI
SiC is transparent not only to IR, but alsoto the visible light spectrum
SiC merged pn-Schottky-Diode
Schottky diode for normal current
pn diode for surge current
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Emission Microscopy - EMMI
higher Vf after extreme stress at high current densities beyondspecification
EMMI shows a reduced effective area
EMMI signature points to extensive crystal defects
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reference fail
Bipolar Degradation
Stacking faults can grow at high current densities triggered byelectron hole recombination.
p+
forwardcharacteristics
before and
curr
entdensi
ty[A
/cm
2]
400
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J.P. Bergmann et al., Mat. Sci. For. Vols. 353-356 (2001), pp 299-302
n- drift layer
cathode
n+ substrate
BPD
growth of stacking faults triggeredby electron-hole-recombination
growth of stacking faults triggeredby electron-hole-recombination
before andafter stress
curr
entdensi
ty[A
/cm
voltage[V]
10 2 3 4
100
0
200
300
Copyright © Infineon Technologies 2011. All rights reserved.
Crystal defect etching
etching in molten KOH at 500°C under a fume hood
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bigger Ni cupsmaller Ni cup withmolten KOH
Ni foil
Ni wire
Ni cage with thesample
tube furnace at IFX
crystall defect etching
size and shape of the etch pits depend on the defect type
no easier procedure is known to decorate crystal defects till now
threading edgedislocation
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Yukari Ishikawa et al., Mat. Sci. For. Vols. 645-648 (2010), pp 351-354
threading screwdislocation
basal planedislocation
dislocation
mechanical cross section is required
saves further investigation with e.g. SCM (ScanningCapacitance Microscopy)
SEM to visualize p doped areas
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misaligned p doping of a JFET
Content
General information
Examples of analysis
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Summary and Outlook
Copyright © Infineon Technologies 2011. All rights reserved.
FA methods, well-known for Si, still applicable for SiC
some work better: “p doped areas under SEM”
some work worse: “crystal defect etching”
Analysis, with all of its methods, can contribute to a betterunderstanding of the material and its failure mechanisms.
Summary and outlook
What is the correlation between the EMMI signature of “bipolardegraded” devices and the triggered crystal defects?
Find an easier method for defect etching
6/19/2013 Page 18Copyright © Infineon Technologies 2011. All rights reserved.
Picture credits
page 4:
http://www.nature.com/nature/journal/v430/n7003/images/430974a-f1.2.jpg
http://atecom.en.alibaba.com/viewimg/picture.html?picture=http://i00.i.aliimg.com/photo/v2/525568278/EPI_Ready_Polish_Wafer_4H_6H_Silicon.jpg
page 5:
https://apec-conf.org/2012/images/PDF/2012/Industry_Sessions/is1.5.5.pdf
http://upload.wikimedia.org/wikipedia/commons/1/15/Toyota_Prius_Plug-In_Hybrid_IAA_2009.jpg
http://www.quantrimang.com.vn/photos/image/032011/29/Us-nasa-columbia.jpg
http://www.greenology.co.za/images/windturbine.jpg
6/19/2013 Copyright © Infineon Technologies 2009. All rights reserved. Page 19