Laser patterning of very thin indium tin oxide thin films on PET substrates

C. McDonnell, D. Milne, C. Prieto, H. Chan, D. Rostohar, G. M. O'Connor

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

This work investigates the film removal properties of 30 nm thick Indium Tin Oxide (ITO) thin films, on flexible polyethylene terephthalate (PET) substrates, using 355, 532 and 1064 nm nanosecond pulses (ns), and 343 and 1064 nm femtosecond pulses. The ablation threshold was found to be dependent on the applied wavelength and pulse duration. The surface topography of the laser induced features were examined using atomic force microscopy across the range of wavelengths and pulse durations. The peak temperature, strain and stress tensors were examined in the film and substrate during laser heating, using finite element computational methods. Selective removal of the thin ITO film from the polymer substrate is possible at all wavelengths except at 266 nm, were damage to substrate is observed. The damage to the substrate results in periodic surface structures (LIPPS) on the exposed PET, with a period of twice the incident wavelength. Fragmented crater edges are observed at all nanosecond pulse durations. Film removal using 1030 nm femtosecond pulses results in clean crater edges, however, minor 5 nm damage to the substrate is also observed. The key results show that film removal for ITO on PET, is through film de-lamination across all wavelengths and pulse durations. Film de-lamination occurs due to thermo-elastic stress at the film substrate interface region, as the polymer substrate expands under heating from direct laser absorption and heat conduction across the film substrate interface.

Original languageEnglish
Pages (from-to)567-575
Number of pages9
JournalApplied Surface Science
Volume359
Early online date19 Oct 2015
DOIs
Publication statusPublished - 30 Dec 2015
Externally publishedYes

Funder

Laser-Connect is a Marie Curie Industry-Academia Partnership and Pathways (IAPP) project funded under EU FP7 (contract 251542). Support from Science Foundation Ireland grant 1319 is also acknowledge

Keywords

  • Ablation
  • Delamination
  • Finite element model
  • Flexible substrate
  • ITO
  • Nanosecond
  • Thin films
  • Transparent conductive layers

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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