Atomic structure and optical properties of plasma enhanced chemical vapor deposited SiCOH low-k dielectric film

Аннотация

The SiCOH low-k dielectric film was grown on Si substrate using plasma enhanced chemical vapor deposition method. Atomic structure and optical properties of the film were studied with the use of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) absorption spectroscopy, Raman spectroscopy and ellipsometry. Analysis of XPS data showed that the low-k dielectric film consists of Si-O4 bonds (83%) and Si-SiO3 bonds (17%). In FTIR spectra some red-shift of Si-O-Si valence (stretching) vibration mode frequency was observed in the low-k dielectric film compared with the frequency of this mode in thermally grown SiO2 film. The peaks related to absorbance by C-H bonds were observed in FTIR spectrum. According to Raman spectroscopy data, the film contained local Si-Si bonds and also C-C bonds in the s-p3 and s-p2 hybridized forms. Scanning laser ellipsometry data show that the film is quite homogeneous, homogeneity of thickness is ~ 2.5%, and homogeneity of refractive index is ~ 2%. According to analysis of spectral ellipsometry data, the film is porous (porosity is about 24%) and contains clusters of amorphous carbon (~ 7%).