Excimer ablation of ITO on flexible substrates for large format display applications

Excimer-based ablative patterning of Indium Tin Oxide (ITO) thin film on flexible substrates has been evaluated for large format display applications. In display package manufacturing, excimer-based ITO ablation can provide a great advantage over conventional photolithographic processing. It can eliminate many steps from the manufacturing cycle, resulting in significant cost reduction. Flexible substrate display packaging is desirable for at least two reasons. It allows roll-to-roll low cost, large volume manufacturing. Its low weight provides for an easy scale up to larger format displays. A XeCl excimer, 1x, amplitude mask pattern projection, scan-and-repeat system was utilized in the evaluation work. The mask pattern had line groupings of line-widths varying from 8 to 30 mum with line length of 44 mm. Lines from all the groupings were simultaneously ablated in 150 nm-thick ITO layer on a flexible 100 mum thick Polyethylene terephtalate (PET) substrate using scanning with optimized dwell duration of 10 pulses and optimized fluence level of 350 mJ/cm(2). Lines ablated with mask line groupings of line-width greater than or equal to 11 mum showed complete electrical isolation indicating complete ITO removal. Scanning Electron Microscopy (SEM) showed the presence of a slight curling effect at ablated line edges. The effect was studied as a function of wavelength and imaging resolution. A CO2 snow cleaning method was evaluated for removing the extruding curled material.