Fabrication of Cu(Ti) Alloy Interconnects with Self-Formation of Thin Barrier Metal Layers Using a High-Pressure Annealing Process

Copper interconnects with self-formed thin TiSixOy barrier layers were successfully fabricated by sequentially depositing Cu(7 at.%Ti) alloys and pure Cu films on SiO2-based substrates with 0.1-μm-wide trenches, and embedding the samples using a high-pressure annealing technique at 550°C and 195 MPa. Microstructural analyses revealed that the self-formed Ti-rich layers with thicknesses of about 5 nm were uniformly formed on the trench bottom and sidewall. In addition, these layers were thermally stable against Cu diffusion into the SiO2-based interlayers. The present study suggests that the Cu-Ti alloy is one of the best candidates among possible interconnect and/or seed layer materials.