Plasma-enhanced atomic layer deposition of Ir thin films for copper adhesion layer

• Published in: Surface & coatings technology Vol. 205; no. 21; pp. 5009 - 5013
• Main Authors: Jeong, Seong-Jun, Shin, Yu-Ri, Kwack, Won-Sub, Lee, Hyung Woo, Jeong, Young-Keun, Kim, Doo-In, Kim, Hyun Chang, Kwon, Se-Hun
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.08.2011; Elsevier
• Subjects: ADHESION; Adhesion layer; Copper; Cross-disciplinary physics: materials science; rheology; Crystallinity; Cu interconnection; DEPOSITION; DIFFUSION BARRIERS; Exact sciences and technology; INFRARED RAYS; Iridium; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; PLASMAS; SURFACE FINISH; Surface roughness; Surface treatments; THIN FILMS; Cu interconnection; Adhesion layer; Iridium; Thin films; Multilayers; Plasma; Surface treatments; Adhesion; Interconnections
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2011.04.094

The crystallinity of a Cu seed layer and its adhesion to a 3 nm-thick TaN diffusion barrier metal were improved by introducing a 3 nm-thick Ir adhesion layer prepared by plasma-enhanced atomic layer deposition (PEALD) using an alternating supply of (ethylcyclopentadienyl)(1,5-cyclooctadien) iridium [Ir(EtCp)(COD)] and NH 3 plasma at 290 °C. The properties of the Ir adhesion layer were carefully compared with those of a Ru adhesion layer. The surface roughness of the Cu layer deposited on the 3 nm-thick Ir adhesion layer improved significantly compared with the 3 nm-thick Ru adhesion layer. Furthermore, the preferential orientation of Cu (111) on the Ir layer was more enhanced than that on the Ru layer due to the low lattice misfit. Consequently, a 10 nm-thick continuous Cu film with root-mean-squared (RMS) surface roughness of 0.7 nm was successfully prepared on a 3 nm-thick Ir film. Also, the 3 nm-thick Ir layer was found to be sufficient as a Cu adhesion layer. ► PEALD-Ir film was prepared as an adhesion layer between Cu and TaN films. ► Cu (111) preferential growth was greatly improved by 3 nm-thick Ir thin film. ► The 3 nm-thick Ir film remarkably enhanced the adhesion between Cu and TaN barrier.