A method for forming a multilayer interconnect includes: a first step of forming
a lower layer interconnect in an upper portion of a first insulating film and then
forming a second insulating film and a third insulating film in this order on the
first insulating film including the lower layer interconnect; a second step of
forming an aperture in part of the third insulating film located above the lower
layer interconnect; a third step of forming an interconnect groove in an upper
portion of the third insulating film so that an upper portion of the aperture is
part of the interconnect groove while reducing the thickness of part of the second
insulating film located under the aperture without having the lower layer interconnect
exposed; a fourth step of removing part of the second insulating film located under
the aperture to expose the lower layer interconnect; and a fifth step of filling
a conductive film in the aperture and the interconnect groove and thereby forming
an upper layer interconnect and a connection portion for electrically connecting
the upper layer interconnect and the lower layer interconnect.