Semiconductor device and method of production of same

A semiconductor device, enabling reliable electrical connection of a main electrode pad with an interconnection pattern without separate provision of a via use electrode pad in addition to the existing main electrode pad, provided with a silicon substrate (semiconductor substrate), an electronic element formation layer formed on one surface of that silicon substrate, an electrode pad having an extension and electrically connected to the electronic element formation layer, a through hole passing through the electrode pad and the silicon substrate, an SiO2 film (insulating film), a via hole provided in the SiO2 film on the extension of the electrode pad, and an interconnection pattern electrically leading out the electrode pad to the other surface of the silicon substrate through the through hole and via hole, said through hole having a diameter larger at a portion passing through the electrode pad than a portion passing through the semiconductor substrate.