Characterization of modified surface of indium tin oxide film during process of laser patterning

Abstract

Effect of excimer laser irradiation at different fluences on Indium-Tin-Oxide films has been studied with use of optical transmission, XRD, Micro-Raman spectra and XPS. Surface modification at low fluence of 154 mJ/cm2 is observed to cause the increase of optical transmittance at initial several pulses of UV laser. At moderate fluence of 239 mJ/cm2, UV laser irradiation results in apparent coloration and chemical compositional change on the ITO surface. XRD results show the grain size of ITO tends to decrease after irradiation. Novel features appear in Raman spectra, which involve the change of surface crystallinity and composition induced by UV laser irradiation. XPS analysis indicates peak shape of O bond is modified post irradiation and Sn/In ratio presents maximum corresponding to dark coloration. ITO films have also been patterned at high fluence of 1-2J/cm2 using simple masks. The ablation rate on laser pulse demonstrates linear change. An alternative method for laser patterning is proposed by combination of excimer laser coloration and visible laser patterning.