Carbonization and transition layer effects on 3C-SiC film residual stress

In this work an extended study of the carbonization process of the silicon surface and of a low temperature transition layer in the temperature rump on the 3C-SiC epitaxial growth has been reported. It has been observed that increasing the C/H2 ratio the voids density decreases, the thickness of the carbonization layer and the density increase and the morphology improves. The low temperature transition layer, grown during the ramp between the carbonization step and the real growth process, produce a further reduction of the voids at the 3C-SiC/Si interface and a considerable reduction of the stress of the 3C-SiC film. This stress reduction is related to a large change of the film morphology. No effect of the interface silicon layer on the stress is observed. This study has shown the complex connection between the first steps of the 3C-SiC growth process and the properties of the film in term of stress and superficial morphology. The residual stress has important implications with regard to the processing (wafer bow) and quality of the epitaxy. Residual stress also changes the mechanical response and/or the resonant frequency of the thin-film structure and may degrade the performance in MEMS-based devices. Therefore, a better understanding of the stress relaxation mechanism could improve the performances of 3C-SiC devices and sensor technologies.