Quantitative structure and property analysis of nanoporous low dielectric constant SiCOH thin films

We have carried out grazing incidence X-ray scattering measurements and specular X-ray reflectivity analysis of the nanoporous structures of low dielectric constant (low k) carbon-doped silicon oxide (SiCOH) films, which were prepared with plasma-enhanced chemical vapor deposition (PECVD) from vinyltrimethylsilane, divinyldimethylsilane, and tetravinylsilane as silane precursors and oxygen gas as an oxidant and then thermally annealed under various conditions. In addition, we measured the refractive indices and dielectric constants of the dielectric films. The nanoporous SiCOH thin films produced in the present study were homogeneous and had well-defined structures, smooth surfaces, and excellent properties and, thus, are suitable for use as low k interdielectric layer materials in the fabrication of advanced integrated circuits. In particular, the vinyltrimethylsilane precursor, which contains only one vinyl group, was found to produce SiCOH films after PECVD and annealing at 450°C for 4 h with the highest population of nanopores and the lowest electron density, refractive index, and dielectric constant.