Enhanced adhesion of plasma-sputtered copper films on polyimide substrates by oxygen glow discharge for microelectronics

• Published in: Thin solid films 2008-02, Vol.516 (8), p.1773-1780
• Main Authors: Lin, Y.-S., Liu, H.-M.
• Format: Article
• Language: English
• Subjects: Adhesion; Atomic force microscopy; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Exact sciences and technology; Ion and electron beam-assisted deposition; ion plating; Materials science; Mechanical and acoustical properties; Metallization; Methods of deposition of films and coatings; film growth and epitaxy; Oxygen plasma; Physical properties of thin films, nonelectronic; Physics; Polymer; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; X-ray photoelectron spectroscopy; XPS
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.07.162

Enhanced plasma-sputtered copper film adhesion onto polyimide substrates treated by oxygen glow discharge was investigated. The peel test demonstrates this improvement, with peel strengths of 0.7–1.2 g/mm for copper films prepared on un-modified polyimide substrates and 195.5–262.2 g/mm for copper films on oxygen plasma-modified polyimide substrates at certain plasma conditions. The enhanced adhesive strengths of plasma-sputtered copper films onto polyimide substrates by oxygen plasmas are due mainly to the increased surface energies of the polyimide substrates. Contact angle measurements indicate that the surface energies of polyimide substrates were greatly increased by oxygen plasmas. X-ray photoelectron spectroscopy analysis shows that the increased surface energies of polyimide substrates using oxygen plasmas occur because of the increased oxygen surface concentration and the increased C–O bond proportion.