Study of well adherent DLC film deposited on piezoelectric LiTaO3 substrate

A well adherent diamond-like carbon (DLC) film was deposited on piezoelectric LiTaO3 substrate using PECVD by inserting SiO2 interlayer. DLC film was characterized using Raman spectroscopy and AFM. Physical and mechanical properties were measured using XRR, ellipsometry, scratch test and nano-indentation. The DLC film exhibits the characteristics of hydrogenated amorphous carbon and a very smooth surface with a 0.25 nm RMS. Scratch test shows that critical load (Lc) is 18 N, which is good enough for applying DLC film to SAW device. The measured mass density, refractive index, hardness and Young's modulus of DLC film deposited on LiTaO3 are comparable to the reported values for hydrogenated amorphous carbon film, irrespective of substrates on which the films were deposited.