A new caged structure spin-on-silica for multilevel interconnect application

A unique, carbon-free silica material, based on a new concept of converting caged (HSiO_3/2)_n structures by eliminating the hydrogens and cross-linking the caged structures with oxygen, was characterized for ILD (interlayer dielectric) applications. The films show excellent uniformity as well as good planarity. At temperatures below 600°C, no volume shrinkage is observed. However, above this temperature, volume losses of as much as 30% can be observed. FTIR (Fourier transform infrared) spectroscopy data and film stress measurements (used to determining film stability) show that a stable crack-free oxide (SiO₂) can be obtained with a high-temperature oven bake or with an optimized process combining low-temperature oven baking and exposure to oxygen plasma. These early results show that this spin-on-silica precursor is suitable for nonetchback processes such as those that involve oxide deposition between polysilicon and the first level of metal. With processing improvements at lower temperatures, the precursor also shows promise for intermetal oxide applications