Thermal conductivity of amorphous SiO₂ thin film: A molecular dynamics study

Amorphous SiO₂ (a-SiO₂) thin films are widely used in integrated circuits (ICs) due to their excellent thermal stability and insulation properties. In this paper, the thermal conductivity of a-SiO₂ thin film was systematically investigated using non-equilibrium molecular dynamics (NEMD) simulations. In addition to the size effect and the temperature effect for thermal conductivity of a-SiO₂ thin films, the effect of defects induced thermal conductivity tuning was also examined. It was found that the thermal conductivity of a-SiO₂ thin films is insensitive to the temperature from -55 °C to 150 °C. Nevertheless, in the range of the thickness in this work, the thermal conductivity of the crystalline SiO₂ (c-SiO₂) thin films conforms to the T^-α with the exponent range from -0.12 to -0.37, and the thinner films are less sensitive to temperature. Meanwhile, the thermal conductivity of a-SiO₂ with thickness beyond 4.26 nm has no significant size effect, which is consistent with the experimental results. Compared with c-SiO₂ thin film, the thermal conductivity of a-SiO₂ is less sensitive to defects. Particularly, the effect of spherical void defects on the thermal conductivity of a-SiO₂ is followed by Coherent Potential model, which is helpful for the design of low-K material based porous a-SiO₂ thin film in microelectronics.