Stability of Cu/Ir/Si trilayer structure to moderate annealing

• Published in: Materials science in semiconductor processing Vol. 12; no. 4; pp. 151 - 155
• Main Authors: Leu, L.C., Norton, D.P., Anderson, T.J., McElwee-White, L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2009; Elsevier
• Subjects: Annealing; Applied sciences; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Compound structure devices; Copper; Cross-disciplinary physics: materials science; rheology; Cu-interconnects; Deposition; Deposition by sputtering; Diffusion barrier; Electronics; Exact sciences and technology; Heat treatment; Iridium; Magnetron sputtering; Materials science; Metals. Metallurgy; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Production techniques; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductors; Silicon; Thin films; Treatment of materials and its effects on microstructure and properties; Diffusion barrier; Cu-interconnects; Iridium; Ultrathin films; Annealing; Material processing; Stacking sequence; Stacking; In situ; Sandwich structure; Multiple layer; X ray diffraction; Thin film; Transmission electron microscopy; Energy dispersion; Interconnection; Integrated circuit; Silicon; Cathodic sputtering; Copper; Diffusion; Interface
• DOI: 10.1016/j.mssp.2009.09.008
• ISSN: 1369-8001

The properties and behavior of trilayer structures consisting of ultrathin iridium thin films sandwiched between Cu and Si have been examined. Iridium thin films (5 nm thick) were deposited on Si substrates using magnetron sputtering, followed by in situ deposition of Cu. The film stacks were examined both as-deposited and after annealing in vacuum over a temperature range of 300–600 °C for 1 h. X-ray diffraction indicates that there is no copper silicide formation upon annealing up to 400 °C. Cross-section HRTEM and EDS line-scans on the sample annealed at 400 °C show the out-diffusion of iridium and the onset of copper diffusion across the interface. The results indicate that iridium is moderately effective as a copper diffusion barrier so long as the processing temperatures remain relatively low.