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  1. Epitaxial growth of SiC on Si covered by SiC nanocrystals G. Battistig, Zs.E. Horváth, L. DobosMTA MFA Research Institute for Technical Physics and Materials Science,P.O.Box 49, H-1525 Budapest, HungaryG. Attolini, M. Bosi, B.E. WattsImem-CNR Institute, Parco Area delle Scienze 37 A, 43010 Fontanini, Parma, Italy

  2. Motivation SiC epitaxy on Si : poor crystalline quality, important stress inside the 3C-SiClayers, 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 Outline

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

  4. 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 interfacesupposed tocontrolthe mechanism Growth mechanism 2CO + 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)sexoterm, - 6 eV

  5. 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

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

  7. 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

  8. 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

  9. SiC Si SiC SiO2 Si SiC (100) Si

  10. 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)

  11. 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

  12. #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

  13. 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

  14. Thank you for your attention!

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