O. Yavas et M. Takai, Effect of substrate absorption on the efficiency of laser patterning of indium tin oxide thin films, J APPL PHYS, 85(8), 1999, pp. 4207-4212
Maskless laser patterning of indium tin oxide thin films for flat panel dis
play applications was studied as a function of wavelength using different h
armonics of a diode-pumped Q-switched Nd:YLF laser. Electrically isolating
lines could be written at all wavelengths used. However, while lines writte
n at the infrared and the visible wavelengths exhibited a ripplelike morpho
logy due to incomplete material removal, ultraviolet laser irradiation prod
uced residue-free etch lines with superior smoothness even at higher scan s
peeds. The threshold fluences for material removal at different wavelengths
were found to correlate with the optical properties of the indium tin oxid
e film. In addition, numerical simulations of laser-induced temperature ris
e yielded peak surface temperatures well above the vaporization temperature
of the indium tin oxide film, indicating that, at all wavelengths studied,
material removal occurs via thermal vaporization. The calculations also re
vealed that the absorption of the ultraviolet laser light by the glass subs
trate is the key factor for the residue-free removal of the indium tin oxid
e film. Moreover, using a flashlamp-pumped Nd:yttrium-aluminum-garnet laser
and a galvanometric scanning system, high process speeds in excess of 1 m/
s could be achieved. (C) 1999 American Institute of Physics. [S0021-8979(99
)03608-7].