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Epitaxial growth of SiC on SiC nanocrystals
Epitaxial growth of SiC on Si
covered by SiC nanocrystals
G. Battistig, Zs.E. Horváth, L. Dobos
MTA MFA Research Institute for Technical Physics and Materials
Science,
P.O.Box 49, H-1525 Budapest, Hungary
G. Attolini, M. Bosi, B.E. Watts
Imem-CNR Institute, Parco Area delle Scienze 37 A, 43010 Fontanini,
Parma, Italy
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
Outline
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Motivation
SiC epitaxy on Si : poor crystalline quality, important
stress inside the 3C-SiC layers, presence of voids at
the 3C-SiC/Si interface
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SiC nanocrystals at SiO2/Si interface
The growth process
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Investigation of the SiC nanocrystals
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SiC epitaxy
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
Growth of the SiC nanocrystals
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(100) Silicon with thermally grown SiO2
Quartz furnace
100% CO
Temperature above 900°C
30min - 8h
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
Growth mechanism
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The carbon accumulation at the interface is
independent from the thickness of the oxide layer
 fast diffusion
Above 900°C from the 3 steps of the carbon
transport (CO entering the oxide, diffusion through
the SiO2, reaction in the Si) the reaction at the
interface supposed to control the mechanism
2 CO + 2 SiO2

[Köhler, 2001]
2 SiO2:Ci,Oi
+ 7eV
2 (CO)g + 2 <SiO2>s

2 <SiC>s + 3 (O2)g
+ 8eV
4 (CO)g + 6 <Si>s

4 <SiC>s + 2 (SiO2)s
exoterm,
- 6 eV
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
TEM measurements
3C-SiC crystallites grow
 epitaxially with the Si matrix
(001) Si || (001) SiC and
[100] Si || [100] SiC
 no voids at the SiC/Si interface
 faster lateral growth
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
Shape and size of SiC nanocrystals grown on (100) Si
(100)
400nm
10
12
10
8
8
z [nm]
z [nm]
6
6
4
4
2
2
18nm
0
0
0
20
40
60
d [nm]
E-MRS 2007 – Strasbourg – Symposium G
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100
0
20
40
60
80
100
d [nm]
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
SEM images of the (100) plane
100 nm SiO2 / Si
1150°C - 100% CO - 90 mins
plan view images after removing
the protective 100 nm thick SiO2
layer with HF
100 nm SiO2 / Si
1150°C - 100% CO - 8 hours
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
The SiC/Si interface
SiO2
SiC
Si
Cross sectional TEM image of a (100) Si/SiO2 system annealed in 100% CO,
1 Bar at 1100oC for 2hrs
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
SiO2
SiC
Si
SiC
(100) Si
E-MRS 2007 – Strasbourg – Symposium G
SiC
Si
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
SiC epitaxy
Horizontal Vapour Phase Epitaxy - reactor at atmospheric pressure,
using propane and silane diluted in hydrogen, induction heating
with a growth temperature of 1200°C
(H2+C3H8+SiH4)
- Etch
(H2)
Temperature
The growth process:
- thermal treatment
(H2)
- carbonisation
(H2+C3H8)
- SiC growth
He at tr e atm ent Car bonis ation
Gr ow th
Final e tch
1200
800
H2+C3H8+Si H4
H2
400
H2
H2+
C3H8
RT
0
E-MRS 2007 – Strasbourg – Symposium G
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H2
20
30
40
Tim e
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
Microscopic structure of epi-SiC
No67
No68
No69
SiC3C
0.045
0.040
0.035
0.030
Counts
#1: 90 mins nc-SiC – low density
- polycrystalline 3C-SiC is formed
(X-ray diffraction)
- well oriented crystals (e-diffraction)
- ~ 70 nm SiC, rough surface and interface
- Void – micropipe formation
0.050
0.025
0.020
0.015
0.010
0.005
0.000
10
20
30
40
50
60
70
80
2-Theta
SiC
Si
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
#2: 8 h nc-SiC – high density
- polycrystalline 3C-SiC layer
- well oriented crystals (e-diffraction)
- ~ 70 nm SiC, smooth surface and interface
- NO pit - void – micropipe formation
SiC
Si
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
Conclusion
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3C-SiC nanocrystals formed at SiO2/Si interface
Seeds for SiC epitaxy
High nc-SiC density – No pits, voids, micropipes
Improvement of the quality of SiC layer is needed
Possible lateral structuring
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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Epitaxial growth of SiC on SiC nanocrystals
Thank you for your
attention!
E-MRS 2007 – Strasbourg – Symposium G
G. Battistig, MTA – MFA Budapest, Hungary
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