Patent ID: 7732925

Claim:
A semiconductor device comprising: a monolithic silicon substrate; a first insulation layer formed on a front surface of the substrate; a pad electrode formed on the first insulation layer; a supporting member bonded to the front surface so as to cover the pad electrode, the substrate having a via hole formed therein and extending from a back surface of the substrate to a surface of the pad electrode; and a second insulation layer formed in the via hole, wherein the via hole comprises a wide portion that is closer to the front surface than to the back surface and is wider than a narrow portion of the via hole that is closer to the back surface than to the front surface, the first insulation layer has an opening located at the pad electrode, and the second insulation layer bends at a boundary between the substrate and the first insulation layer so as to extend into the opening to cover a side edge of the first insulation layer in the opening to prevent insulation failure in the via hole, and one end of the wide portion of the via hole is at a plane defined by the front surface of the substrate.