Study of leakage mechanism and trap density in porous low-k materials

The field and temperature dependence of the leakage current of low-k material is studied by using planar capacitors. First it is shown that our planar capacitors are suitable test vehicles to analyze the intrinsic properties of low-k materials. Then an evaluation of the trap density of the investigated low-k material is performed. Eventually different models such as Poole-Frenkel emission, Schottky emission and trap-assisted Fowler-Nordheim tunneling are analyzed in a temperature range from 80 K to 473 K and in a field range from 4.2 MV/cm to 6.6 MV/cm. It is found that Poole-Frenkel emission and Schottky emission do not fit the experimental data, whereas trap-assisted Fowler-Nordheim tunneling exhibits an adequate match between the extracted parameters and the theoretical predictions.