Micro-assembly of three dimensional tetrahedra by capillary forces

This paper presents the realization of micrometer sized silicon nitride tetrahedra with well-defined angles that are folded out of a planar geometry using capillary forces. The required specific three-dimensional shape is achieved by a well-defined folding sequence. Using the favorable properties of the recently developed corner lithography technique, a programmable stop hinge is micro-machined by etching specifically defined intersection planes of the silicon mold. Tetrahedra were successfully folded by capillarity validating this new technique. The demand for such a microstructure has become very large since it can form the essential basic element for future three-dimensional data storage systems.