Synthesis and Characterization of Siof Thin Films Deposited by Ecrcvd for Ulsi Multilevel Interconnections

Abstract

AbstractLow dielectric constant fluorine doped silicon oxide films were deposited by using ECR plasma CVD with SiF4 and O2 as source gases diluted in Ar gas. Characterization of films was carried out in terms of various gas flow ratios (SiF4/O2 = 0.2 ∼ 1.6). The microwave power and substrate temperature during deposition were fixed at 700W and 300°C, respectively. The chemical bonding structure of the films was evaluated by Fourier transform infrared spectroscopy (FTIR), fluorine concentration by X-ray photoelectron spectroscopy (XPS) and refractive index by ellipsometry. Dielectric constant was determined from C-V measurements at 1MHz. FTIR spectra shows that as the fluorine concentration increases, peak intensities of Si-F bonding and shoulder peak at around 1160cm−1 of Si-O stretching mode increased. Moreover, with increasing the fluorine concentration in the SiOF film, the peak position of Si-O stretching mode shifts to the higher wavenumber side. The Si-F2 bond peak is observed to rise when the SiF4/O2 gas flow ratio is larger than 1.0. Refractive index and film density decreased with increasing the SiF4/O2 gas flow ratio. The SiOF film deposited at SiF4/O2 gas flow ratio of 1.0 exhibited fluorine content of 11.8 at.% and dielectric constant of 3.14.