The structural and dielectric properties of SiOx/a-C,F/SiOx multi-layer thin films deposited by microwave electron cyclotron resonance plasma method

SiOx/a-C,F/SiOx multi-layer films were prepared by microwave electron cyclotron resonance plasma method using SiH4 (20% diluted by Ar) and O2, CHF3 and CH4 as precursor gases, respectively. The Fourier transform infrared (FTIR) absorption spectroscopy shows the typical C-F, CC, Si-O, and C-H configurations in the multi-layer films. Meanwhile, because of the “history effect” of the chamber wall rather than interface reaction between a-C,F film and SiOx film, a small amount of Si-C and Si-F components exists in the middle a-C,F film layer, which is confirmed by profile analysis of Auger electron spectroscopy. Furthermore, no obvious structural changes occur for SiOx/a-C,F/SiOx multi-layer films in the FTIR spectra after thermal annealing, while only 8% of increase in the film dielectric constant happens due to some expansion for the film thickness after 400 °C annealing. SiOx/a-C,F/SiOx sandwich structure might be regarded as one of the low-k dielectric candidates for interlayer dielectrics in ultra-large-scale integrated circuit.