To impart high reliability for suppressing the deterioration of EM (electromigration) resistance and the increase in contact resistance by preventing the reduction of the contact area between an upper wiring layer and a connecting plug in a connecting hole for connection with the wiring layer for the borderless connecting-hole wiring structure of a semiconductor device having a borderless connecting-hole wiring structure.

This manufacturing method has (a) the process for forming a connecting hole 3 in an innerlayer insulating film 2 on a substrate 1, (b) the process for forming a connecting plug 4 by embedding conducting material in the connecting hole 3 and (c) the process for forming an upper wiring layer 5 on the innerlayer insulating film 2. In this case, the connecting plug is formed so that the connecting-plug length becomes shorter than the depth of the connecting hole in the process (b). In the process (c), even when the upper wiring layer does not cover the entire surface of the opening surface of the connecting hole, a part of the upper wiring layer is embedded in the connecting hole so that the upper surface of the connecting plug or the upper surface of a contact layer for the upper wiring layer formed at the part thereof is not exposed.