plasma etch and deposition solutions for sic and gan devices...mv/decade) and low-field mobility...

© Oxford Instruments 2018 CONFIDENTIAL

Plasma etch and deposition solutions

for SiC and GaN devices

Oxford Instruments Plasma Technology

TechLounge, Semicon Europa 2018


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


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


• 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 ”


GaN RF Device Solutions


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


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


• 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


• 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

)


• 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

http://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwix37Kbw4TOAhXBLcAKHfcPAnkQjRwIBw&url=http://www.swagelok.com/en/catalog/Product/Detail?part=6LVV-ALD3FR4-P-CV&psig=AFQjCNEq3bOJmb7BEf7GLnx0BtSUof4ZkA&ust=1469189390530629


• 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


• 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.


• 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


SiC Power Device Solutions


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


• 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


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


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

plasma etch and deposition solutions for sic and gan devices...mv/decade) and low-field mobility...

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