Patent ID: 7671636

Claim:
A switching circuit comprising: a transistor having a first electrode, a second electrode and a control electrode; a zener diode; and a capacitor, wherein a connection between the first electrode and the second electrode is capable of temporally switching between a conduction state and a non-conduction state by switching a control voltage of the transistor, the zener diode and the capacitor are coupled in series between the first electrode and the control electrode of the transistor, the first electrode is a drain or a collector, the transistor, the zener diode, and the capacitor are disposed on a semiconductor substrate, the capacitor includes an embedded conductive region and a coating insulation region, the embedded conductive region extends from a first surface to a second surface of the semiconductor substrate, the coating insulation region covers the embedded conductive region so that the embedded conductive region is electrically insulated from the semiconductor substrate, the control electrode has a depth from the first surface of the substrate, the embedded conductive region has a depth from the first surface of the substrate, and the depth of the control electrode is equal to the depth of the embedded conductive region.