Manufacturing method of semiconductor device
View Patent ↗A method of forming a metal interconnection that has a favorable cross-sectional shape is provided without the fear of side etching, even in a sparse arrangement of metal interconnections. The method, the following structure is employed. A region for placing a dummy metal interconnection is provided close to a region in which a metal interconnection is formed. A trench is formed in the dummy metal interconnection region and a resist pattern for the metal interconnection is then formed, giving the resist above the trench a large surface area per unit area. The metal interconnection is subsequently formed by dry etching in which an organic component from the resist above the trench forms a solid sidewall protection film, permitting anisotropic etching. The metal interconnection can thus have a favorable cross-sectional shape.
1. A method of manufacturing a semiconductor device having a metal interconnection on a semiconductor substrate, comprising the steps of:
forming an interlayer insulating film on the semiconductor substrate;
forming a trench in the interlayer insulating film and the semiconductor substrate for forming a dummy metal interconnection, the trench having an opening whose diameter is twice or longer of a total film thickness of a metal film and a resist film the diameter having an aspect ratio in the range of 1 to 3;
forming a metal film on a surface of the interlayer insulating film and inside the trench by deposition;
forming a pattern with a resist on the metal film; and
etching the metal film to form the metal interconnection on the interlayer insulating film and the dummy metal interconnection inside and around the trench close to each other.
2. A method of manufacturing a semiconductor device according to claim 1 , wherein; in the step of forming a pattern with a resist on the metal film, a part of the resist above the trench is exposed to reduce a thickness of the resist film.
3. A method of manufacturing a semiconductor device according to claim 2 , wherein; the exposed part of the resist above the trench is circular in plan view.
4. A method of manufacturing a semiconductor device according to claim 2 , wherein; the exposed part of the resist above the trench is quadrangular in plan view.
5. A method of manufacturing a semiconductor device according to claim 3 , wherein; a plurality of the circular exposed part of the resist is formed above a single trench.
6. A method of manufacturing a semiconductor device according to claim 4 , wherein; a plurality of the quadrangular exposed part of the resist is formed above a single trench.
7. A method of manufacturing a semiconductor device according to claim 1 , wherein; the metal film is formed from aluminum, or an aluminum alloy containing one out of silicon and copper.