Semiconductor device having a reduced surface field strength
First Claim
1. A semiconductor device having a semiconductor body comprising a substrate region of a first conductivity type, a surface-adjoining layer-shaped semiconductor region provided at the surface of said substrate region, at least a substrate region-adjoining part of said layer-shaped semiconductor region being of a second conductivity type opposite to that of said first type and forming a p-n junction with said substrate region, an island-shaped part of said layer-shaped semiconductor region being bounded laterally by a separation region which extends from the surface over substantially the whole thickness of the semiconductor region, at least a first zone of a semiconductor circuit element being provided within said island-shaped part, the overall net doping of the second conductivity type of said layer-shaped semiconductor region in atoms per unit of surface area being sufficiently small such that when a voltage in the reverse direction is applied across said p-n junction the depletion zone within the island-shaped part will extend at least locally from said p-n junction up to the surface at a voltage which is lower than the breakdown voltage of the p-n junction, at least a part of said island-shaped part of the layer-shaped semiconductor region having a doping profile comprising at least two overlying layer portions of different average net doping concentrations between said substrate and said surface.
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Abstract
A semiconductor device of the "RESURF" type has a substrate region and a superimposed semiconductor layer which forms a p-n junction with the substrate region. The semiconductor layer has an island-shaped region which is depleted at least locally up to the surface at a reverse voltage applied across the p-n junction which is well below the breakdown voltage of the p-n junction. According to the invention the island-shaped part of the semiconductor layer over at least a part of its area has a doping profile in the vertical direction with at least two overlying layer portions with different average net doping concentrations and of the same or opposite conductivity type, so as to increase the current-carrying capacity of the semiconductor layer.
49 Citations
21 Claims
- 1. A semiconductor device having a semiconductor body comprising a substrate region of a first conductivity type, a surface-adjoining layer-shaped semiconductor region provided at the surface of said substrate region, at least a substrate region-adjoining part of said layer-shaped semiconductor region being of a second conductivity type opposite to that of said first type and forming a p-n junction with said substrate region, an island-shaped part of said layer-shaped semiconductor region being bounded laterally by a separation region which extends from the surface over substantially the whole thickness of the semiconductor region, at least a first zone of a semiconductor circuit element being provided within said island-shaped part, the overall net doping of the second conductivity type of said layer-shaped semiconductor region in atoms per unit of surface area being sufficiently small such that when a voltage in the reverse direction is applied across said p-n junction the depletion zone within the island-shaped part will extend at least locally from said p-n junction up to the surface at a voltage which is lower than the breakdown voltage of the p-n junction, at least a part of said island-shaped part of the layer-shaped semiconductor region having a doping profile comprising at least two overlying layer portions of different average net doping concentrations between said substrate and said surface.
Specification