Selective etching of ultrafast laser modified sapphire

M. Kaiser; M. Kumkar; R. Leute; J. Schmauch; R. Priester; J. Kleiner; M. Jenne; D. Flamm; F. Zimmermann

doi:10.1117/12.2509415

4 March 2019 Selective etching of ultrafast laser modified sapphire

M. Kaiser, M. Kumkar, R. Leute, J. Schmauch, R. Priester, J. Kleiner, M. Jenne, D. Flamm, F. Zimmermann

Proceedings Volume 10905, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXIV; 109050F (2019) https://doi.org/10.1117/12.2509415
Event: SPIE LASE, 2019, San Francisco, California, United States

Abstract

Due to its hardness and scratch resistance sapphire is a favorite material for various high-quality applications e.g. in consumer electronics. Because of those excellent properties sapphire is a demanding material regarding processing. Using ultrashort pulses in combination with beam shaping offers the possibility to deposit energy precisely into the material and modify in a controlled manner reducing thermally induced stress and avoiding microcracks. Separation along modified paths especially for inner contours is still an open task. Selective etching of laser modified sapphire is a promising technology to release outer contours as well as inner contours and even smallest through holes. By using Bessel-like beam profiles an amorphized elongated modification in the monocrystalline bulk along the whole material thickness can be achieved by a single pulse. The amorphous phase in contrast to the monocrystalline sapphire is etchable in 30 wt.-% KOH solution. For a successful process development, a fundamental comparison of different types of modification and its etching behavior depending on pulse duration, pulse energy, number of pulses, spatial and temporal distances of modifications at a wavelength of 1030 nm is carried out. The etching rate depends on the processing and etch solution parameters and is optimized to 10 μm/min. Besides the contours a nanosieve consisting of two-dimensional arranged crack free nanoholes (200 nm in diameter, 5 μm in distance) is realized with an aspect ratio of 1:1500.

Citation Download Citation

M. Kaiser, M. Kumkar, R. Leute, J. Schmauch, R. Priester, J. Kleiner, M. Jenne, D. Flamm, and F. Zimmermann "Selective etching of ultrafast laser modified sapphire", Proc. SPIE 10905, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXIV, 109050F (4 March 2019); https://doi.org/10.1117/12.2509415

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