Patent ID: 7304356
Filing Date: 2007-12-04
Classification: H01L

Abstract:
1. A semiconductor chip of improved voltage-withstanding capability, comprising: (a) a semiconductor substrate having a first and a second major surface and a set of side surfaces therebetween; (b) a first semiconductor region of a first conductivity type formed in the substrate and exposed at the second major surface thereof; (c) a second semiconductor region of a second conductivity type, opposite to the first conductivity type, formed in the substrate and exposed at the first major surface thereof; (d) there being a junction of opposite conductivity types between the first and the second semiconductor region; (e) there being an annular trench formed in the first major surface of the substrate and extending through the second semiconductor region into the first semiconductor region; (f) a first electrode on the substrate electrically coupled to the second semiconductor region; (g) a second electrode on the substrate electrically coupled to the first semiconductor region; (h) a dielectric layer received in the trench and held against the second semiconductor region; and (i) an electroconductive layer received in the trench and placed against the second semiconductor region via the dielectric layer, the electroconductive layer being electrically coupled to the first semiconductor region; (j) whereby, when the opposite-conductivity-type junction between the first and the second semiconductor region of the substrate is reverse biased, the electroconductive layer creates in the second semiconductor region a depletion layer which is joined to a depletion layer created in the second semiconductor region by the opposite-conductivity-type junction, thereby preventing current leakage from the side surfaces of the substrate.