Subtractive Etch of Ruthenium for Sub-5nm Interconnect

Ruthenium has been recently considered as a promising candidate to replace copper as the BEOL interconnect material for sub-5nm technology nodes. In this work, single level Ru interconnects were fabricated in imec's 300-mm pilot line using EUV lithography and the subtractive etch of Ru films. Lines with critical dimension smaller than 10.5 nm were formed and electrically tested to assess the line resistance of patterned Ru. Using the TCR method, structures with resistivity of 15 μΩ.cm and cross-sectional area of 200 nm² were obtained and benchmarked against analogous Ru and Cu damascene processes. Ru lines with aspect ratio up to 3.8 were fabricated and measured having line resistance below 500 Ω/μ m at 12 nm CD. Ru is expected to outperform damascene Cu at this scale, supporting the potential insertion of Ru metal patterning for advanced technology nodes.