Preparation and Characterization of Ultralow-Dielectric-Constant Porous SiCOH Thin Films Using 1,2-Bis(triethoxysilyl)ethane, Triethoxymethylsilane, and a Copolymer Template

摘要

Ultralow-dielectric-constant (k) porous SiCOH films have been prepared using 1,2-bis(triethoxysilyl)ethane, triethoxymethylsilane, and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer template by means of spin-coating. The resulting films were characterized by cross-section scanning electron microscopy, small-angle x-ray diffraction, atomic force microscopy, Fourier-transform infrared spectroscopy, nanomechanical testing, and electrical measurements. Thermal treatment at 350 deg C for 2 h resulted in the formation of ultralow-k films with k of approx2.0, leakage current density of 3 X 10~(-8) A/cm~(2) at 1 MV/cm, reduced modulus (E_(r)) of approx4.05 GPa, and hardness (H) of approx0.32 GPa. After annealing between 400 deg C and 500 deg C for 30 min, the resulting films showed fluctuant k values of 1.85 to 2.22 and leakage current densities of 3.7 X 10~(-7) A/cm~(2) to 3 X 10~(-8) A/cm~(2) at 0.8 MV/cm, likely due to the change of the film microstructure. Compared with 350 deg C annealing, higher-temperature annealing can improve the mechanical strength of the ultralow-k film, i.e., E_(r) approx= 5 GPa and H approx= 0.56 GPa after 500 deg C annealing.