Chemical vapor deposition of organosilicon composite thin films for porous low-k dielectrics

Abstract

Pulsed plasma enhanced chemical vapor deposition has produced organosilicon thin films with the potential use as low dielectric constant interconnect materials in microelectronic circuits. Both diethylsilane and octamethylcyclotetrasiloxane precursors were used, with oxygen and hydrogen peroxides oxidants respectively, to deposit low-k organosilicon films. FTIR, nanoindentation, ellipsometry, and dielectric constant measurements were demonstrated as a valuable film characterization tools to understand structure-property-processing fundamentals by quantifying structural bonding environments and relating those to the film properties. Nanocomposites were also produced using two novel techniques. First, crystal colloidal templates of polystyrene nanospheres were fabricated using evaporation-induced self-assembly. OSG was then deposited throughout the templates to create composite materials. Subsequently the polystyrene was removed upon thermal annealing to create highly porous OSG thin films. Second, ultrasonic atomization was used to deliver particles into a vacuum chamber during plasma-enhanced CVD of the organosilicon matrix to create composite thin films using an all-CVD technique. This process could extend CVD to applications currently only possible using wet processing techniques or multi-step processing.