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Interfacial transition layer in thermally grown SiO2 film on 4H-SiC

The uniformity of SiO2 films thermally grown on 4H-SiC was characterized by atomic force microscopic observation of the SiO2 surface after each step-etching with HF solution. It was found that roughness of the emerged SiO2 surface drastically increases near the SiO2/SiC interface, which indicates that the film quality near the interface is not two-dimensionally uniform. The film density profile led to the model that the non-uniformity was generated by segregation of C impurities followed by CO adsorption, and the film uniformity was gradually improved during the subsequent oxidation by shrinkage of open spaces.