Method of manufacturing a semiconductor device comprising a silicon body, in which a sunken oxide layer is locally provided

摘要

The method of the present invention involves the forming of a depression with sidewalls extending below a first oxidation mask provided on a surface of a silicon body. Subsequently, after the sidewalls of the depression have been provided with a second oxidation mask, an oxidation treatment is carried out. According to the invention, the depression is provided in such a manner that the sidewalls of the depression are flat and form an angle of 25 DEG to 45 DEG with the original surface of the silicon body. The second oxidation mask is formed by a 5 to 50 nm thick layer of silicon nitride or silicon oxinitride applied directly or separated from the surface by a layer of silicon oxide having a thickness of less than 5 nm. This leads to a very flat structure.