Mechanical properties of low k SiO₂ thin films templated by PVA

Porous silica films as low-k interlayer dielectric were prepared via a sol-gel method. Tetraethoxysilane (TEOS) was used as raw material and polyvinyl alcohol (PVA) with different degrees of polymerization as molecular template. The precursor was deposited on to coated platinum silicon substrates and annealed at different temperatures. The films were modified with trimethylchlodrosilane (TMCS) for hydrophobicity, which can make the porous films present a stable characteristic of low k. The effects of annealing temperature and polymerization degree of PVA on mechanical properties were investigated. Significant improvement occurred for the sample annealed at 700 °C, the hardness and the Young modulus of the silica film templated by HPVA are 0.91 GPa and 15.37 GPa, respectively. These values are comparable with that of MOCVD low k silica sample.