F2-laser patterning of indium tin oxide (ITO) thin film on glass substrate

This paper reports the controlled micromachining of 100 nm thick indium tin oxide (ITO) thin films on glass substrates with a vacuum-ultraviolet 157 nm F-2 laser. Partial to complete film removal was observed over a wide fluence window from 0.49 J/cm(2) to an optimized single pulse fluence of 4.5 J/cm(2) for complete film removal. Optical microscopy, atomic force microscopy, and energy dispersive X-ray analysis show little substrate or collateral damage by the laser pulse which conserved the stoichiometry, optical transparency and electrical conductivity of ITO coating adjacent to the trenches. At higher fluence, a parallel micron sized channel can be etched in the glass substrate. The high photon energy and top-hat beam homogenized optical system of the F-2 laser opens new means for direct structuring of electrodes and microchannels in biological microfluidic systems or in optoelectronics.