Layer-by-layer 3D printing of Si micro- and nanostructures by Si deposition, ion implantation and selective Si etching

In this paper we report a method for layer-by-layer printing of three-dimensional (3D) silicon (Si) micro- and nanostructures. This fabrication method is based on a sequence of alternating steps of chemical vapor deposition of Si and local implantation of gallium (Ga⁺) ions by focused ion beam (FIB) writing. The defined 3D structures are formed in a final step by selectively wet etching the non-implanted Si in potassium hydroxide (KOH). We demonstrate the viability of the method by fabricating 2 and 3-layer 3D Si structures, including suspended beams and patterned lines with dimensions on the nm-scale.