Characterization of an ultra-low k SiO2 thin film prepared by molecular template

Using the molecular template method, we synthesized a nanoporous SiO2 thin film with ultra-low dielectric constant (k). Fourier transform infrared spectroscopy and differential thermal analysis were carried out to investigate the effect of n-hexane washing on the film properties before and after the surface modification process. The results showed the important role of the washing process, and revealed that –CH3bonds substituted for –OH bonds in the films modified by trimethylchlorosilane (TMCS)/n-hexane solution, which avoided the destruction of the network structure of the thin films. The nanometre pore size (10–20 nm), good network structure and thickness of SiO2 films were observed by scanning electron microscopy (SEM). The effects of the post-treatment conditions on the dielectric constant (1.5) and the porosity (78%) of the films were also investigated.