Patent ID: 7094684

Claim:
A method of manufacturing a semiconductor device comprising the steps of: forming a semiconductor layer over an insulating surface; forming a first insulating film over the semiconductor layer; forming a first wiring comprising at least a laminate of a first conductive film with a property as a barrier and a second conductive film containing copper as its main component, said step of forming a first wiring including the steps of: (i) forming the first conductive film over the first insulating film; (ii) etching the first conductive film; (iii) forming the second conductive film on the first conductive film through an opening of a mask; (iv) reducing a width of the second conductive film with dry etching; doping an impurity element into the semiconductor layer with the first wiring as a mask to form an impurity region; forming a second insulating film over the first wiring; forming a contact hole to reach the impurity region in the second insulating film; and forming a second wiring electrically connected to the impurity region over the second insulating film.