Effect of DC negative bias on microstructure and surface morphology of amorphous silicon carbide films prepared by HWP-CVD

Abstract

The effect of DC negative bias (− Vs) on microstructure and surface morphology of amorphous silicon carbide thin films prepared by helicon wave plasma chemical vapor deposition is reported. Microstructure and surface morphology were obtained by scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the increase of − Vs on the substrate make a more compact film and lower surface roughness, which can reach 0.56 nm. The XRD analysis reveals that the SiC thin films are of an amorphous structure. Percentages of carbon and silicon atoms (C/Si) were measured by energy dispersive spectrometer (EDS), and the C/Si ratio can reach 1.45. The structural properties of the films were studied by Raman spectroscopy techniques and Fourier transform infrared (FTIR). It is found that the films contain not only Si–C bonds but also Si–CHx bonds. Raman spectra results show that the proportion of disordered carbon in the films decreases with the increase of − Vs. The results of ultra-microhardness tester show that the hardness of the films increases with the increase of − Vs and the maximum mechanical hardness can reach 18.5 GPa at − Vs = − 60 V.