Improvement of microstructure property of low dielectric constant nanoporous SiOF thin films prepared by sol–gel method

Using hydrofluoric acid (HF) as acid catalyst, F doped nanoporous low-k SiO2 thin films were prepared through sol–gel method. Compared with the hydrochloric acid (HCl) catalyzed film, the films showed better micro-structural and dielectric properties. The improvements were investigated by high-resolution scanning electron microscopy (HR-SEM), Fourier transform infrared spectroscopy (FTIR), and capacitance–voltage (C–V) and current–voltage (I–V) techniques. The results of N2 adsorption/desorption further confirmed the HR-SEM morphologies and indicated that the suited introduction of HF increased the porosity and decreased the pore size distribution (about 10 nm). The incorporation of HF effectively adjusts the microstructures and the chemical bonds, and thus significantly improves the dielectric properties of the films; the dielectric constant was reduced to 1.5.