Structure Characterization of HSQ Films for Low Dielectrics Using D5 as Sacrificial Porous Materials

Low-density materials, commercially available hydrogensilsesquioxane (HSQ) offer a low dielectric constant. HSQ films can be obtained by spin on deposition (SOD). In this work, low-dielectric-constant HSQ films are prepared by using D5 (decamethylcyclopentasiloxane) as sacrificial porous materials. The dielectric constant of silica films significantly changes from 3.0 to 2.4. We report the structural aspects of the films in relation to their composition after annealed at 300°C, 400°C, and 500°C for 1.5h in nitrogen ambient and annealed at 400°C for 1.5h in vacuum. Si--OH appears after annealed at
400°C for 1.5h in vacuum. The results indicate that the proper condition is in nitrogen ambient. Intensity of the Si--H peak increases with the increasing temperature. Fourier transform infrared spectroscopy is used to identify the network structure and cage structure of Si--O--Si bonds and other possible bonds. Dielectric constant k is significantly lowered by annealing at 350°C for 1.5h in nitrogen ambient. The I--V and C--V measurements are used to determine the dielectric constant, the electric resistivity and the breakdown electric field.