Semiconductor device and method of manufacturing same

A semiconductor device comprising:

• a first semiconductor substrate having a first surface and a second surface opposite the first surface;
• a first insulating film formed on the first surface;
• a first hole formed in the first insulating film and partially extending into the first semiconductor substrate;
• a second hole formed in the second surface;
• a single-piece first electrode entirely filling the first hole and comprising a portion that extends above the first insulating film, the portion being shaped to be inserted into a fourth hole of a third semiconductor substrate;
• a pad formed between the first insulating film and the first electrode;
• and
• a conductive film conformally formed in the second hole, the conductive film being electrically connected to a bottom surface of the first electrode and leaving a third hole in the first semiconductor substrate open, the third hole being configured to receive a second electrode of a second semiconductor substrate;
• wherein the second hole does not reach the pad.