High-temperature interfacial reaction of an Al thin film with single-crystal 6H-SiC

Interfacial reactions between an Al thin film and a single-crystal (001) 6H-SiC substrate were investigated using x-ray diffraction and cross-sectional transmission electron microscopy. Aluminum thin films were prepared by radio-frequency magnetron sputtering method on 6H-SiC substrates at room temperature and then annealed at various temperatures from 500 to 900 degreesC. A columnar-type polycrystalline Al thin film was formed on a 6H-SiC substrate in the as-deposited sample. No remarkable microstructural change, compared to the as-deposited sample, was observed in the sample annealed at 500 degreesC for 1 h. However, it was found that the Al layer reacted with the SiC substrate at 700 degreesC and formed an Al-Si-C ternary compound at the Al/SiC interface. Samples annealed at 900 degreesC showed a double-layer structure with an Al-Si mixed surface layer and an Al-Si-C compound layer below in contact with the substrate.