Page 1© Oxford Instruments 2018 CONFIDENTIAL
Plasma etch and deposition solutions
for SiC and GaN devices
Oxford Instruments Plasma Technology
TechLounge, Semicon Europa 2018
Page 2© Oxford Instruments 2018 CONFIDENTIAL
Oxford Instruments Plasma Technology
• Unrivalled plasma processing knowledge
• Install base > 3000
End market segments
Academic
51%
Commercial
49%
We take cutting edge research technology to production
Lab
✓ Leading technology
enabling new applications
✓ Maximised device
performance
Fab
✓ High reliability on high end
platforms
✓ Low Cost of ownership with
maximised yield
✓ Responsive service
Design leading plasma processing
etch and deposition solutions for
Lab to Fab
Page 3© Oxford Instruments 2018 CONFIDENTIAL
Discrete
GaN SiC material for RF and
Power devices. Failure
analysis (Metal, polymer, Si)
Sensors
IR sensors, VOx, Si, Quartz
MEMS
Optoelectronics
Laser and LED based on
InP, GaN, GaAs
Nanotechnology
Graphene, MoS2, WS2 …
Biomedicals
Micro fluidics coating and
new materials
OI market overview
Page 4© Oxford Instruments 2018 CONFIDENTIAL
• Adoption of wide band gap power conversion devices
with improved efficiency over silicon.
• OIPT solutions developed to support fabrication of
HEMTs, Inverter, MOSFET, IGBT, rectifier, filters…
• Processing solutions tailored to Compound
semiconductor requirements with patented clamping
technology and optimised chemistry.
Automotive – Power conversion
“ Smart Green World for a more sustainable energy and
better device energy efficiency ”
Page 5© Oxford Instruments 2018 CONFIDENTIAL
GaN RF Device Solutions
Page 6© Oxford Instruments 2018 CONFIDENTIAL
Front end processing solution for e mode GaN HEMT
Our offering
✓ Gate recess and passivation on
same platform using ALE and
ALD.
✓ Control of material quality at gate
interface.
✓ Fast Via process selective to
GaN
Recessed gate
After etching, RMS~0.43nm
Before etching, RMS~0.41nm
Simplified Front end process flowOIPT solutions shown in orange
SiC via
dry etching
Gate recess
ALE dry etchGate passivation
Page 7© Oxford Instruments 2018 CONFIDENTIAL
Atomic Layer Etching
• Single atomic layers etching
• Precise control of etching depth
• Extremely low damage
• Plasma Technology large experience in providing
ALD equipments makes us a supplier of choice for
ALE.
• PlasmaPro 100 customized for ALE processing
• Patent application EP16187143
Low damage etch solution for very thin layers
Plasma Pro 100 ALE
configuration
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• Cyclical ALE process enables
precise control and low damage
• Plasma can be on throughout
cycle (or be switched on/off)
ALE of AlGaN and GaN
Oxidising dose gas,
e.g. N2O for
controlled oxidation
Cl2 etch gas removes
the oxidised layer
Oxidation is
self-limiting
AlGaN
Oxidised surface
AlGaN
Oxidised surface
AlGaN
Oxidised surface
AlGaN
Oxidised surface
O O
Cl Cl Cl
1
2
3
4
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• Etch rate 1.5-3 Å/cycle
• up to 18 Å/min
• Uniformity <±5% over 200mm
• Added roughness <<1nm
• AFM data indicates a smoothing effect
AlGaN/GaN ALE results: Ar/Cl2
0
1
2
3
4
5
6
7
0 10 20 30 40
AlG
aN E
PC
(Å/c
ycle
)
DC bias (V)
with Cl2
No Cl2
AlGaN surface roughness after 200 cycles,
left = before etching, right = after etching
AFM data courtesy of Paolo Abrami in Collaboration with Bristol
University
(pm
)
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• Specially configured for ALE:
• Fast recipe control down to 10ms
• ALD-style gas dose delivery using
“ALD valves” with 10ms open-close
response
• Ability to operate as a standard etch
tool or in fast low power ALE mode.
Mode selection via software recipe
control
• PlasmaPro100 Cobra300
Oxford Instruments ALE tool
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• Key application: ALD of high-quality Al2O3 to control GaN interface
• Effective passivation and isolation through excellent electrical properties
• Optimized for sensitive interfaces to minimize interface states and border
traps
ALD of gate dielectric for low Dit
GaN
buffer
AlGaN
Si substrate
S DG
ALD materials of interest for
GaN passivation and dielectric
deposition:
• Al2O3
• AlN, SiNx, GaN
• HfO2, SiO2
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• Use plasma treatments to form high-quality nitride interlayer.
Nitride interlayer as pretreatment for HEMTs
Yang et al., IEEE Electron Device Lett. 34, 1497 (2013)
Chen et al., Phys. Status Solidi A (2014) / DOI 10.1002/pssa.201431712
Strong reduction of Ga-O bonds
Electrical characteristics:
• small sub-threshold swing 64 mV/dec
• a small hysteresis of 0.09 V
• low interface trap density of 1-6×1012 cm-2
eV-1.
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• Epitaxial growth of ALD AlN using
TMA and H2/N2 plasma at 300 °C.
Followed by ALD Al2O3 gate
dielectric.
• TFTs with good gate control with
low subthreshold swing (∼85
mV/decade) and low-field mobility
(∼27 cm2/(V·s)).
Epitaxial AlN for GaN thin-film transistor
Liu et al., IEEE Electron Device Lett. 34, 1106
(2013)
Liu et al., Phys. Status Solidi C 11, 953 (2014)
Epitaxial 4 nm AlN on GaN
close to AlN
composition
Thin-film transistor design
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SiC Power Device Solutions
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Our offering
✓ Controlled roughness for
improved leakage current
✓ Excellent profile from vertical to
sloped with no micro-trenching for
better device breakdown
✓ Conformal coatings with
exceptional fill capability
Front end processing solution for SiC MOSFET
SiC based inverter
Simplified Front end process flowOIPT solutions shown in orange
Hardmask
dry etching
SiC features
dry etching
Feature refill
ALD
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• Challenges• Reducing Surface Roughness
• Improve leakage current
• Reducing Micro-trenching
• Improve Device Breakdown
• Sidewall Angle control
• From vertical to sloped profile
Challenges in SiC Trench Etch
Micro-trenching
Sidewall
Roughness
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SiO2 Hard Mask and SiC Trench Etch
Befo
re E
tch
Afte
r Etc
h o
f SiO
2and S
iC
• Process Results• No Micro Trench
• Etch Rate > 700
nm/min
• Sel SiC:SiO2 > 2.1:1
• Profile ~ 86°
• Uniformity > +/- 2.2%
• Extremely smooth
Page 18© Oxford Instruments 2018 CONFIDENTIAL
RF and Power Semiconductor Summary
• Market leading solutions for high volume manufacturing
• Process and equipment designed to provide maximum yield up to 150mm
wafer size at market leading cost of Ownership
• Global Support infrastructure to satisfy production customer’s
requirements
Page 19© Oxford Instruments 2018 CONFIDENTIAL