Producing a buried cavity in a semiconductor substrate

In a method for producing a buried cavity in a semiconductor substrate, trenches are produced in a surface of a semiconductor substrate down to a depth that is greater than cross-sectional dimensions of the respective trench in a cross section perpendicular to the depth, wherein a protective layer is formed on sidewalls of the trenches. Isotropic etching through bottom regions of the trenches is carried out. After carrying out the isotropic etching, the enlarged trenches are closed by applying a semiconductor epitaxial layer to the surface of the semiconductor substrate.