Picosecond ablation of silicon nitride using 532 nm master oscillator fiber power amplifier for patterning crystalline silicon photovoltaic cells

Abstract

Laser processing is integral to the manufacture of advanced photovoltaic cells, including crystalline silicon and thin film devices. Continuous improvement and innovation in laser processing methods and laser architectures are needed to further improve device efficiencies and reduce overall device manufacturing costs. In particular, patterning silicon nitride and silicon oxide on single and polycrystalline silicon devices is needed to improve front side and back side metallization processes. In this paper, we present results for picosecond ablation of silicon nitride deposited on single crystalline silicon using a 532 nm master oscillator fiber power amplifier. A low ablation threshold value of 0.1 J/cm2 was observed when processing at a pulse repetition frequency of 200 KHz and 30 ps pulsewidth. This ablation threshold value is comparable to that previously reported for selective removal of silicon nitride from monocrystalline and polycrystalline silicon using a 355 nm hybrid (fiber-bulk) laser source and is substantially lower than the ablation threshold value reported using a 355 nm q-switched diode-pumped Nd:YVO4 laser source. Excellent laser scribe results were obtained at fluence values of several times ablation threshold. Further optimization of the process conditions is expected to result in a robust laser process suitable for industrial adoption.Laser processing is integral to the manufacture of advanced photovoltaic cells, including crystalline silicon and thin film devices. Continuous improvement and innovation in laser processing methods and laser architectures are needed to further improve device efficiencies and reduce overall device manufacturing costs. In particular, patterning silicon nitride and silicon oxide on single and polycrystalline silicon devices is needed to improve front side and back side metallization processes. In this paper, we present results for picosecond ablation of silicon nitride deposited on single crystalline silicon using a 532 nm master oscillator fiber power amplifier. A low ablation threshold value of 0.1 J/cm2 was observed when processing at a pulse repetition frequency of 200 KHz and 30 ps pulsewidth. This ablation threshold value is comparable to that previously reported for selective removal of silicon nitride from monocrystalline and polycrystalline silicon using a 355 nm hybrid (fiber-bulk) laser source an...