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Wafer-level integration of self-aligned high aspect ratio silicon 3D structures using the MACE method with Au, Pd, Pt, Cu, and Ir

: Franz, M.; Junghans, R.; Schmitt, P.; Szeghalmi, A.; Schulz, S.E.

Fulltext ()

Beilstein Journal of Nanotechnology 11 (2020), pp.1439-1449
ISSN: 2190-4286
Journal Article, Electronic Publication
Fraunhofer IOF ()
Fraunhofer ENAS ()
black silicon; bottom-up; metal-assisted chemical etching (MACE); nanowires; wafer-level integration

The wafer-level integration of high aspect ratio silicon nanostructures is an essential part of the fabrication of nanodevices. Metal-assisted chemical etching (MACE) is a promising low-cost and high-volume technique for the generation of vertically aligned silicon nanowires. Noble metal nanoparticles were used to locally etch the silicon substrate. This work demonstrates a bottom-upself-assembly approach for noble metal nanoparticle formation and the subsequent silicon wet etching. The macroscopic wafer patterning has been done by using a poly(methyl methacrylate) masking layer. Different metals (Au, Pt, Pd, Cu, and Ir) were investigated to derive a set of technologies as platform for specific applications. Especially, the shape of the 3D structures and the resulting reflectance have been investigated. The Si nanostructures fabricated using Au nanoparticles show a perfect light absorption with a reflectance below 0.3%. The demonstrated technology can be integrated into common fabrication processes for microelectromechanical systems.