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

摘要

In this method, after a first oxidation mask (21) has been provided on a surface of the silicon body (1), a depression (40) with side walls (41) extending below the first oxidation mask (21) is formed in the silicon body (1). Subsequently, after the side walls (41) have been provided with a second oxidation mask (70), an oxidation treatment is carried out. According to the invention, the depression (40) is provided in a manner such that the side walls (41) areflat and enclose an angle (42) of 25 DEG to 45 DEG with the original surface, while the second oxidation mask (70) is formed by a 5 to 50 nm thick layer (71) of silicon nitride or silicon oxynitride, which is applied directly or separated therefrom by a layer of silicon oxide (72) having a thickness of less than 5 nm to the side walls. The method leads to a very flat structure.