Epitaxial growth of SiC on SiC nanocrystals 1 E-MRS 2007 – Strasbourg – Symposium GG. Battistig,...

Epitaxial growth of SiC on SiC nanocrystals

1E-MRS 2007 – Strasbourg – Symposium G G. Battistig, MTA – MFA Budapest, Hungary

Epitaxial growth of SiC on Si Epitaxial growth of SiC on Si covered by SiC nanocrystals covered by SiC nanocrystals

G. Battistig, Zs.E. Horváth, L. DobosG. Battistig, Zs.E. Horváth, L. DobosMTA MFA Research Institute for Technical Physics and Materials

Science,P.O.Box 49, H-1525 Budapest, Hungary

G. Attolini, M. Bosi, B.E. WattsG. Attolini, M. Bosi, B.E. WattsImem-CNR Institute, Parco Area delle Scienze 37 A, 43010

Fontanini, Parma, Italy



OutlineOutline

Motivation Motivation SiC epitaxy on Si :SiC epitaxy on Si : poor crystalline quality, poor crystalline quality, important stress inside the 3Cimportant stress inside the 3C--SiCSiC layerslayers, , presence of voids presence of voids at the 3C-SiC/Si interfaceat the 3C-SiC/Si interface

SiC nanocrystals at SiOSiC nanocrystals at SiO22/Si interface/Si interface The growth process The growth process

Investigation of the SiC nanocrystalsInvestigation of the SiC nanocrystals

SiC epitaxySiC epitaxy



GGrowth of the SiC nanocrystalsrowth of the SiC nanocrystals

(100) (100) Silicon with thermally grown SiOSilicon with thermally grown SiO22

Quartz furnaceQuartz furnace 100% CO100% CO Temperature above 900Temperature above 900°°CC 30min - 8h30min - 8h



The carbon accumulation at the interface is independent from The carbon accumulation at the interface is independent from the thickness of the oxide layer the thickness of the oxide layer fast diffusionfast diffusion

Above 900Above 900°°C from the 3 steps of the carbon transport (CO C from the 3 steps of the carbon transport (CO entering the oxide, diffusion through the SiOentering the oxide, diffusion through the SiO22, reaction in the Si) , reaction in the Si) the the reaction at the interfacereaction at the interface supposed tosupposed to controlcontrol the the mechanismmechanism

2 CO + 2 SiO2 2 SiO2:Ci,Oi [Köhler, 2001] + 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

Growth mechanismGrowth mechanism



3C-SiC crystallites gr3C-SiC crystallites grow ow epitaxially with the Si matrixepitaxially with the Si matrix (001) Si (001) Si |||| (001) SiC and (001) SiC and

[100] Si [100] Si |||| [100] SiC [100] SiC no voids at the SiC/Si interfaceno voids at the SiC/Si interface faster lateral growth faster lateral growth

TEM measurementsTEM measurements



0 20 40 60 80 100

0

2

4

6

8

10

z [n

m]

d [nm]

0 20 40 60 80 100

0

2

4

6

8

10

12

z [n

m]

d [nm]

18nm

Shape and size of SiC nanocrystalsShape and size of SiC nanocrystals grown on grown on ((100)100) Si Si

400nm

(100)(100)



SEM images of the (100) planeSEM images of the (100) plane

plan view images after plan view images after removing the protective 100 removing the protective 100 nm thick SiOnm thick SiO22 layer with HF layer with HF

100 nm SiO100 nm SiO22 / Si / Si

1150°C - 100% CO - 90 mins1150°C - 100% CO - 90 mins

100 nm SiO100 nm SiO22 / Si / Si

1150°C - 100% CO - 8 hours1150°C - 100% CO - 8 hours



The SiC/Si interfaceThe SiC/Si interface

SiOSiO22

SiSi

SiCSiC

Cross sectional TEM image of a (100) Si/SiOCross sectional TEM image of a (100) Si/SiO22 system annealed in system annealed in 100% CO, 1 Bar at 1100100% CO, 1 Bar at 1100ooC for 2hrsC for 2hrs



SiOSiO22

(100) Si(100) Si

SiCSiC SiCSiC

SiSi

Si

SiC



0 10 20 30 40

RT

400

800

1200

Time

Tem

pe

ratu

re

Heat treatment Carbonisation Growth Final etch

H2 H2+

C3H8

H2

H2H2+C3H8+SiH4

HHorizontal Vapour Phase Epitaxyorizontal Vapour Phase Epitaxy - - reactor at atmospheric reactor at atmospheric pressure, using propane and silane diluted in hydrogenpressure, using propane and silane diluted in hydrogen, , induction heating with a growth temperature of 1200°Cinduction heating with a growth temperature of 1200°C

SiC epitaxySiC epitaxy

The growth The growth process:process: - - thermal treatmentthermal treatment (H (H22) ) - - carbonisationcarbonisation (H (H22+C+C33HH88))- - SiC growthSiC growth (H(H22+C+C33HH88+SiH+SiH44))- Etch- Etch (H (H22))



Microscopic structure of epi-SiCMicroscopic structure of epi-SiC#1: 90 mins nc-SiC – low density#1: 90 mins nc-SiC – low density

- polycrystalline 3C-SiC is formed polycrystalline 3C-SiC is formed (X-ray diffraction) (X-ray diffraction)- well oriented crystals (e-diffraction)well oriented crystals (e-diffraction)- ~ 70 nm SiC, rough surface and ~ 70 nm SiC, rough surface and interfaceinterface- Void – micropipe formation Void – micropipe formation

SiCSiC

SiSi



#2: 8 h nc-SiC – high density#2: 8 h nc-SiC – high density- polycrystalline 3C-SiC layerpolycrystalline 3C-SiC layer- well oriented crystals (e-diffraction)well oriented crystals (e-diffraction)- ~ 70 nm SiC, smooth surface and interface~ 70 nm SiC, smooth surface and interface- NO pit - void – micropipe formation NO pit - void – micropipe formation

SiCSiC

SiSi



ConclusionConclusion

3C-SiC nanocrystals formed at SiO3C-SiC nanocrystals formed at SiO22/Si interface/Si interface Seeds for SiC epitaxySeeds for SiC epitaxy High nc-SiC density – No pits, voids, micropipes High nc-SiC density – No pits, voids, micropipes Improvement of the quality of SiC layer is needed Improvement of the quality of SiC layer is needed Possible lateral structuring Possible lateral structuring



Thank you for your Thank you for your attention!attention!

Epitaxial growth of SiC on SiC nanocrystals 1 E-MRS 2007 – Strasbourg – Symposium GG. Battistig,...

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