Progress in Laser Inscription in Semiconductors by Multiphoton-Initiated Nanosecond Infrared Pulse Absorption.

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Bibliographic Details
Title:	Progress in Laser Inscription in Semiconductors by Multiphoton-Initiated Nanosecond Infrared Pulse Absorption.
Authors:	Sopeña, Pol¹ pol.sopena-martinez@univ-amu.fr, Ganguly, Niladri¹, Spühler, Gabriel², Selivanau, Andrei², Grojo, David¹
Source:	Journal of Laser Micro / Nanoengineering. Aug2025, Vol. 20 Issue 2, p119-126. 8p.
Subjects:	Semiconductors, Multiphoton absorption, Laser pulses, Laser engraving, Photonics, Silicon industry, Refractive index
Abstract:	Recent advances in high-power nanosecond laser sources in the infrared have led to applications in imaging and ranging. Laser processing can also benefit from these as they potentially trigger nonlinear absorption mechanisms expanding the number of processable materials. Particularly in semiconductors, these result in local intensities modest enough to avoid detrimental nonlinear propagation and pre-focal plasma screening typically observed with ultrashort pulses. Nonetheless, they allow initiating local energy deposition by multiphoton absorption and induce permanent modifications. In this work, we evaluate the potential of two nanosecond sources with different wavelengths to induce volume modifications in silicon and other semiconductors. We first review previous experiments performed at 1.55 μm, to later focus on a systematic study at 2.8 μm, and finally compare the results. In both cases, Si bulk modifications are observed. Interestingly, for 2.8 μm compared to 1.55 μm, we report a decrease in the energy threshold for volume modification with depth, reproducible rear surface modification, and the ability to write through Ge layers. With both configurations, we measure a positive refractive index variation of ~0.5%, suitable for writing light-guiding structures. This shows the potential of nanosecond infrared pulses for writing complex 3D structures turned to Si photonics and microelectronics packaging. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	Recent advances in high-power nanosecond laser sources in the infrared have led to applications in imaging and ranging. Laser processing can also benefit from these as they potentially trigger nonlinear absorption mechanisms expanding the number of processable materials. Particularly in semiconductors, these result in local intensities modest enough to avoid detrimental nonlinear propagation and pre-focal plasma screening typically observed with ultrashort pulses. Nonetheless, they allow initiating local energy deposition by multiphoton absorption and induce permanent modifications. In this work, we evaluate the potential of two nanosecond sources with different wavelengths to induce volume modifications in silicon and other semiconductors. We first review previous experiments performed at 1.55 μm, to later focus on a systematic study at 2.8 μm, and finally compare the results. In both cases, Si bulk modifications are observed. Interestingly, for 2.8 μm compared to 1.55 μm, we report a decrease in the energy threshold for volume modification with depth, reproducible rear surface modification, and the ability to write through Ge layers. With both configurations, we measure a positive refractive index variation of ~0.5%, suitable for writing light-guiding structures. This shows the potential of nanosecond infrared pulses for writing complex 3D structures turned to Si photonics and microelectronics packaging. [ABSTRACT FROM AUTHOR]
ISSN:	18800688
DOI:	10.2961/jlmn.2025.02.2005