Effect of Oxygen Plasma on Low Dielectric Constant HSQ (Hydrogensilsesquioxane) Films

The commercially available hydrogensilsesquioxane (HSQ) offers a low dielectric constant. In this paper, the impact of oxygen plasma treatment has been investigated on the low-k HSQ films. Fourier transform infrared (FTIR) spectroscopy was used to identify the network structure and cage structure of Si-O-Si bonds and other possible bonds after treatments. C-V and I-V measurements were used to determine the dielectric constant, the electronic resistivity and the breakdown electric field, respectively. The result indicates that oxygen plasma treatment will damage the HSQ films by removing the hydrogen content. Both dielectric constant and leakage current density increase significantly after oxygen plasma exposure. The dielectric constant and leakage current density can both be decreased by annealing at 350°C for 1.5 h in nitrogen ambient. The reason is that the open porous of the external films can be modified and density of thin film be increased. The rough surface can be smoothed.