A method for manufacturing a semiconductor device includes a step of
forming a first groove in a first insulating film, forming a conductive
film in the first groove, a step of selectively forming a second
insulating film on the conductive film and the first insulating film, a
step of forming a second groove by removing part of the conductive film
using the second insulating film as a mask, the second groove being
formed so as to form a connecting portion of the conductive film under
the second insulating film and form a first wiring layer by forming the
connecting portion with a bottom of the first groove integrally with each
other as one unit.