Patterning of Crystalline ITO Using Infrared Nanosecond Fiber Laser Pulses

Abstract

A method is proposed for patterning crystalline indium tin oxide (c-ITO) patterns from amorphous ITO (a-ITO) thin films on glass substrate, using infrared nanosecond fiber laser-induced crystallization followed by chemical etching. In the proposed approach, the a-ITO film is selectively transformed into a c-ITO film over a predetermined area via the laser direct writing, and the unirradiated a-ITO film is then removed using an acidic etchant solution, resulting in the formation of c-ITO pattern on the substrate because the a-ITO has a higher etching rate than the c-ITO does. The fabricated c-ITO patterns are observed using optical microscopy and scanning electron microscopy (SEM). The crystalline, optical, electrical properties were measured by X-ray diffraction (XRD), a spectrophotometer, and a two probe station, respectively. The experimental results show that a high pulse repetition rate reduces thermal shock and yields a corresponding improvement in the physical properties of the c-ITO patterns.