Laser structuring of conducting films on transparent substrates for electronics devices

Abstract

Flat panel displays (FPD), flexible electronics and thin-film photovoltaics are booming in the last few years. Permanent annual growth and huge expectations in the market in the near future stimulate the development of versatile technologies for patterning thin-film materials on rigid and flexible substrates. Utilization of laser radiation provides diversity of processing means for structuring deposited films. The high selectivity and diminishing effect on the surrounding material as well as high speed are required in processing complex multilayered systems in the thin-film photovoltaics. Organic electronics imposes special requirements on the geometrical quality of conductors. The current situation with laser direct writing of thin-films in the production of FPD and solar cells as well as our results are presented. High repetition rate lasers with a short pulse duration offer new possibilities for high efficiency structuring of conducting, semi-conducting and isolating films. Laser structuring with the picosecond and nanosecond pulse duration was applied in shaping the thin films deposited on polymers and glass substrates. Absorption of laser radiation by the film material was essential to initiate its controllable removal. Use of UV laser radiation with fluences close to the ablation threshold made it possible to minimize surface contamination and the recast ridge formation during the ablation process. The flexible technique of patterning was applied in prototyping the components for the OLED matrix, RFID antennas and the thin-film solar cells. Well-defined shapes of isolating trenches and conductor lines were produced by laser ablation with the picosecond pulse duration.