Axicon-lens-doublet focusing for the fabrication of ultra-high-aspect-ratio structures through silicon with infrared ultrafast lasers

Niladri Ganguly; Pol Sopeña; David Grojo

doi:10.1117/12.3017566

20 June 2024 Axicon-lens-doublet focusing for the fabrication of ultra-high-aspect-ratio structures through silicon with infrared ultrafast lasers

Niladri Ganguly, Pol Sopeña, David Grojo

Author Affiliations +

Proceedings Volume 13005, Laser + Photonics for Advanced Manufacturing; 130050L (2024) https://doi.org/10.1117/12.3017566
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

We demonstrate how the implementation of an axicon-lens doublet can lead to an efficient beam-shaping solution for laser processing of semiconductors. By generating high-angle pseudo-Bessel beams with 50-ps 1550-nm pulses, we can write high-aspect-ratio structures inside silicon and approach results similar to those today demonstrated in dielectrics. For the first time, we show how repeated laser irradiations with our shaped beam lead to permanent modifications that spontaneously grow shot-after-shot from the front to the rear surface of 1-mm thick crystalline wafers. Although direct microexplosion and drilling remain inaccessible, our work evidences a novel self-induced percussion writing modality leading to the formation of uniform and reproducible elongated modifications with aspect ratios as high as ∼700, obtained without any relative motion of the beam focus. Quantitative phaseimaging reveals light-guiding characteristics associated to these structures, according to a measured high positive index change exceeding ∼10⁻². This opens the door to unique monolithic solutions for optical through-siliconvias, which could be potentially a key element for ultrafast vertical interconnections in next-generation silicon chips.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Niladri Ganguly, Pol Sopeña, and David Grojo "Axicon-lens-doublet focusing for the fabrication of ultra-high-aspect-ratio structures through silicon with infrared ultrafast lasers", Proc. SPIE 13005, Laser + Photonics for Advanced Manufacturing, 130050L (20 June 2024); https://doi.org/10.1117/12.3017566

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