Characteristics of fluorinated amorphous carbon films and implementation of 0.15 μm Cu/a-C:F damascene interconnection

Fluorinated amorphous carbon films $\mathrm{(a-}\mathrm{C:F})$ deposited by plasma enhanced chemical vapor deposition with low dielectric constant $\text{(K∼2.3),}$ thermal stability (higher than 400 °C) and acceptable adhesion to a cap layer such as SiOF or ${\mathrm{SiO}}_{\mathrm{2}}$ were obtained by varying the range of content ratios between carbon and fluorine, the rf power, the process pressure and the base temperature. Standard x-ray photoelectron spectroscopy and thermal desorption spectroscopy metrologies were employed to characterize the deposited $\mathrm{a-}\mathrm{C:F}$ films. The damascene pattern with 0.15 μm and an etching selectivity of more than 50 $\mathrm{(a-}{\mathrm{C:F/SiOF, SiO}}_{\mathrm{2}})$ was implemented by a mixture of etching gases of ${\mathrm{N}}_{\mathrm{2}}{\mathrm{+O}}_{\mathrm{2}}.$ The bias power, rf power and gas flows were incorporated to optimize the etching recipe for achieving a damascene profile with a high aspect ratio. The scanning electron microscope results showed that a better etch profile can be obtained at higher bias power. In our damascene architecture, the etching stop layer or hard mask of both SiOF and ${\mathrm{SiO}}_{\mathrm{2}}$ was studied. The SiOF, providing a lower dielectric constant than ${\mathrm{SiO}}_{\mathrm{2}},$ would especially reduce the entire effective dielectric constant. Furthermore, we integrated electroplated copper into trenches or vias as small as 0.15 μm, with aspect ratio of 6.