Fabrication method and apparatus for fabricating a spatial structure in a semiconductor substrate

A method for fabricating spatially etched structures in a semiconductor substrate made of a semiconductor material, which comprises the steps of:

• producing a depth structure in the semiconductor substrate, proceeding from a surface of the semiconductor substrate;
• applying an etching-resistant layer in a collar region of a sidewall of the depth structure, resulting in the sidewall covered with the etching-resistant layer being substantially etch resistant during subsequent etching steps;
• forming a potential field in the semiconductor substrate around the depth structure;
• and
• etching a spatial structure with an aid of an etchant introduced into the depth structure, the etching proceeding from a region of the depth structure that is not covered by the etching-resistant layer, the etchant being chosen such that an etching direction being dependent on the potential field, and a form of the spatial structure also being dependent on the potential field.