Structure-Property Relationships of Amorphous Hydrogenated Silicon-Carbon Films Produced by Atomic Hydrogen-Induced CVD from a Single-Source Precursor

Amorphous hydrogenated silicon-carbon (a-Si:C:H) films were produced by atomic hydrogen-induced (AH) CVD using hexamethyldisilane (HMDS) as a single-source precursor. Radio frequency (rf) hydrogen plasma was the source of atomic hydrogen. The effect of substrate temperature (T s ) on the chemical structure, composition, surface morphology, mechanical properties (dynamic hardness, total stress), and optical properties (refractive index, optical bandgap) of a-Si:C:H film has been examined. Fourier transform infrared (FTIR) spectroscopy and Auger electron spectroscopy (AES) data revealed a drastic drop in hydrogen content in the film, and a rise of the atomic concentration ratio Si/C with increasing T s , thus accounting for the elimination of organic moieties from the film and the formation of a Si-carbidic structure. In the light of scanning electron microscopy (SEM) and atomic force microscopy (AFM) examinations, the films were found to be morphologically homogeneous materials with a maximum size of surface roughness not exceeding 2 nm at T s = 300 °C. Both hardness and stress (tensile in nature) are strongly affected by the film composition, their values increasing with rising atomic ratio Si/C. The investigated optical properties of a-Si:C:H film, i.e., refractive index (n) and optical bandgap (E 0 ). can be controlled by the atomic ratio Si/C for a wide range of values: n = 1.58-2.02 and E 0 = 2.3-3.2 eV.