In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon

• Published in: Nature photonics Vol. 11; no. 10; pp. 639 - 645
• Main Authors: Tokel, Onur, Turnalı, Ahmet, Makey, Ghaith, Elahi, Parviz, Çolakoğlu, Tahir, Ergeçen, Emre, Yavuz, Özgün, Hübner, René, Zolfaghari Borra, Mona, Pavlov, Ihor, Bek, Alpan, Turan, Raşit, Kesim, Denizhan Koray, Tozburun, Serhat, Ilday, Serim, Ilday, F. Ömer
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-10-2017; Nature Publishing Group
• Subjects: 639/624/1075/1079; 639/624/1075/1080; 639/624/399/1099; 639/624/400/385; Applied and Technical Physics; Chip formation; Damage; Electronic devices; Electronic equipment; Etching; Fabrication; Integration; Ion etching; Laser applications; Lasers; Letter; Lithography; Mechanical systems; Microelectronics; Microfluidics; Optical components; Optics; Photonics; Photovoltaics; Physics; Physics and Astronomy; Quantum Physics; Reactive ion etching; Silicon
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-017-0004-4

Silicon is an excellent material for microelectronics and integrated photonics
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–
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, with untapped potential for mid-infrared optics
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. Despite broad recognition of the importance of the third dimension
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,
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, current lithography methods do not allow the fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realized with techniques like reactive ion etching. Embedded optical elements
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, electronic devices and better electronic–photonic integration are lacking
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. Here, we demonstrate laser-based fabrication of complex 3D structures deep inside silicon using 1-µm-sized dots and rod-like structures of adjustable length as basic building blocks. The laser-modified Si has an optical index different to that in unmodified parts, enabling the creation of numerous photonic devices. Optionally, these parts can be chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface—that is, ‘in-chip’—microstructures for microfluidic cooling of chips, vias, micro-electro-mechanical systems, photovoltaic applications and photonic devices that match or surpass corresponding state-of-the-art device performances.
By exploiting dynamics arising from nonlinear laser–material interactions, functional microelements and arbitrarily complex 3D architectures deep inside silicon are fabricated with 1 μm resolution, without damaging the silicon above or below.