Method for forming wiring, semiconductor device, and method for manufacturing semiconductor device
A wiring which is formed using a conductive film containing copper and whose shape is controlled is provided. A transistor including an electrode which is formed in the same layer as the wiring is provided. Further, a semiconductor device including the transistor and the wiring is provided. A resist mask is formed over a second conductive film stacked over a first conductive film; part of the second conductive film and part of the first conductive film are removed with use of the resist mask as a mask so that the first conductive film has a taper angle greater than or equal to 15° and less than or equal to 45°; and the resist mask is removed. The first conductive film contains copper.
1. A method for forming a wiring, comprising the steps of:
forming a first conductive film comprising copper over a substrate;
forming a second conductive film comprising at least one of tungsten, cobalt, nickel, tin, and molybdenum over the first conductive film;
forming a resist mask over the second conductive film;
etching a part of the second conductive film with use of the resist mask as a mask;
oxidizing the second conductive film to oxidize copper in the first conductive film with oxygen which moves from the second conductive film to the first conductive film;
removing part of the first conductive film so that the first conductive film has a taper angle greater than or equal to 15° and less than or equal to 45°; and
removing the resist mask.
2. The method for forming a wiring according to claim 1 further comprising the step of:
removing a region of the second conductive film after removing the resist mask, wherein the region is not in contact with the first conductive film.
3. The method for forming a wiring according to claim 1 ,
wherein a region of the first conductive film which is in contact with the second conductive film is etched more rapidly than other region of the first conductive film which is not in contact with the second conductive film.
4. The method for forming a wiring according to claim 1 ,
wherein an insulating film comprising nitrogen or a conductive film comprising nitrogen is provided under the first conductive film.
5. The method for forming a wiring according to claim 1 ,
wherein the second conductive film is removed after removing the resist mask.