Penetration of copper-manganese self-forming barrier into SiO₂ pore-sealed SiCOH during deposition

The incorporation of a self-forming Cu diffusion barrier on pore-sealed SiCOH was investigated. SiCOH films 20% porous and 230 nm thick were capped with 36 nm SiO₂. Fabricated structures (Cu-Mn/SiO₂/SiCOH) were subjected to a back-side Secondary Ion Mass Spectrometry (SIMS) depth profile study to assess the extent of metal migration. SIMS depth profiles revealed that Cu and Mn diffused in significant amounts across the SiO₂ layer during fabrication steps. A mass transport model was used to describe the migration of metal species. The diffusion coefficient for Cu in the SiO ₂ pore-sealing layer is approximately D∼5.62 × 10- ¹⁶ cm²/sec.