Micro-Raman spectroscopy as a tool to analyze mechanical stress in nano-structured diamond-like carbon films

In this work, we deposited nano-structured diamond-like carbon (DLC) films by high density plasma chemical vapour deposition system (HDPCVD) and the study of mechanical stress of these films has been made using micro-Raman spectroscopy. Recently developed high-density plasma chemical vapour deposition techniques have made it possible to produce nano-structured DLC films with low surface roughness and high sp(3)/sp(2) hybridization ratio. Thus, these parameters have been studied in this work. Nano-structured DLC films were obtained using four methods for the surface modification of the silicon wafers: diamond powder, surface roughness generated by plasma etching, surface roughness generated by wet chemical etching solution and reference sample (silicon wafer only submitted to a chemical clean). The samples were analysed by AFM and SEM, too. We related the mechanical stress with the position of G and D bands, creating a new method to analyze these films (analyzing the displacement of central position G band). Thus, the results obtained in this work, related the Raman spectroscopy bands with the mechanical stress in DLC films obtained with different surface topographies.