Epitaxial growth of SiC on Si covered by SiC nanocrystals G 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

Outline Motivation SiC epitaxy on Si : poor crystalline quality, important stress inside the 3C-SiC layers, presence of voids at the 3C-SiC/Si interface SiC nanocrystals at SiO2/Si interface The growth process Investigation of the SiC nanocrystals SiC epitaxy

Growth of the SiC nanocrystals (100) Silicon with thermally grown SiO2 Quartz furnace 100% CO Temperature above 900°C 30min - 8h

Growth mechanism 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  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

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

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

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

SiO2 SiC Si The SiC/Si interface Cross sectional TEM image of a (100) Si/SiO2 system annealed in 100% CO, 1 Bar at 1100oC for 2hrs

SiC SiO2 Si SiC Si SiC (100) Si

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 The growth process: - thermal treatment (H2) - carbonisation (H2+C3H8) - SiC growth (H2+C3H8+SiH4) - Etch (H2)

Microscopic structure of epi-SiC #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 SiC Si

SiC Si #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

Conclusion 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

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