Interface formation between metals (Cu, Ti) and low dielectric constant organic polymer (FLARE™ 1.0)

The continuing trend toward miniaturization of integrated circuits is driving the development of low dielectric constant materials $\text{(k<3)}$ and their integration with copper metallization. In this work, the interface formed between copper or titanium and low dielectric constant polymer was explored. Fluorinated poly(arylene ether) (FLARE™ 1.0) was studied as an example of fluorinated organic polymers. X-ray photoelectron spectroscopy (XPS) was used to study the chemical interactions between the metal and FLARE™ 1.0 during interface formation. XPS revealed that copper is relatively unreactive with FLARE™ 1.0 compared to titanium. However, depositing the copper by rf sputtering caused significant defluorination of the FLARE™ 1.0 surface, which was not evident for thermally evaporated copper. No copper fluoride formation was observed for either deposition. Evaporation of titanium does cause defluorination of the polymer, with subsequent formation of titanium fluoride. Titanium is more reactive than copper and forms bonds of T–C, Ti–O, and Ti–F at the interface.