Method for etching 3d structures in a semiconductor substrate, including surface preparation

The present invention is related to method for producing 3D structures in a semiconductor substrate using Deep Reactive Ion Etching (DRIE), comprising at least the steps of: - providing a substrate (1), and then - grinding the backside of the substrate in order to achieve a thinned substrate, wherein extrusions (2) and native oxides (3) are left after said grinding step, and then - performing a surface treatment selected from the group consisting of a wet etching step and a dry etching step in order to remove at least said native oxides (3) and extrusions (2) on the surface of said backside of the substrate which are causes for the grass formation during subsequent etching, and then - performing deep reactive ion etching in order to achieve 3D vias.