Fabrication of local areas of high aspect ratio silicon structures using metal-assisted chemical etching

Within this work, we present the successful integration of the metal assisted chemical etching into a wafer fabrication regime. We created local areas, which contains 3D silicon structures with a high aspect ratio by a bottom-up approach. The catalytic wet etching process involved gold nano-particles with a median diameter of 7.8 nm to etch silicon at the metal silicon interface solely. This resulted in 0.9 μm long vertical silicon rods. This gives a platform for a low-cost fabrication of devices with integrated 3D structures.