Power semiconductor rectifier with ring-shaped trenches
First Claim
1. A semiconductor device, comprising:
- a semiconductor substrate having a first major surface, an opposing second major surface, and a first conductivity type;
an anode electrode formed on the first major surface of the semiconductor substrate;
a plurality of Schottky contacts between the anode electrode and the semiconductor substrate;
a cathode region formed on a surface layer of the second major surface of the semiconductor substrate; and
a cathode electrode formed on the cathode region on a side of the cathode region opposite the second major surface of the semiconductor substrate, wherein each of the Schottky contacts assumes, in the first major surface, a plane shape of a circle or a polygon, the polygon having apices arranged on the circumference a circle, and straight lines connecting the centers of the circles or the polygons adjacent to one another form a triangular lattice.
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Abstract
A high-speed, soft-recovery semiconductor device that reduces leakage current by increasing the Schottky ratio of Schottky contacts to pn junctions. In one embodiment of the present invention, an n− drift layer is formed on an n+ cathode layer 1 by epitaxial growth, and ring-shaped ring trenches having a prescribed width are formed in the n− drift layer. Oxide films are formed on the side walls of each ring trench. The ring trenches are arranged such that the centers of the rings of the ring trenches adjacent to one another form a triangular lattice unit. A p− anode layer is formed at the bottom of each ring trench. Schottky contacts are formed at the interface between an anode electrode and the surface of the n− drift layer. Ohmic contact is established between the surfaces of polysilicon portions and the anode electrode.
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Citations
26 Claims
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1. A semiconductor device, comprising:
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a semiconductor substrate having a first major surface, an opposing second major surface, and a first conductivity type;
an anode electrode formed on the first major surface of the semiconductor substrate;
a plurality of Schottky contacts between the anode electrode and the semiconductor substrate;
a cathode region formed on a surface layer of the second major surface of the semiconductor substrate; and
a cathode electrode formed on the cathode region on a side of the cathode region opposite the second major surface of the semiconductor substrate, wherein each of the Schottky contacts assumes, in the first major surface, a plane shape of a circle or a polygon, the polygon having apices arranged on the circumference a circle, and straight lines connecting the centers of the circles or the polygons adjacent to one another form a triangular lattice. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A semiconductor device, comprising:
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a semiconductor substrate;
an anode electrode formed on one surface of the semiconductor substrate;
a plurality of ring-shaped trenches formed in the one surface of the semiconductor substrate, wherein centers, on the one surface of the semiconductor substrate, of each of the trenches form vertices of a triangular lattice;
a plurality of first Schottky contacts between the anode electrode and portions of the semiconductor substrate located inside the trenches; and
a plurality of second Schottky contacts between the anode electrode and portions of the semiconductor substrate located outside the trenches.
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26. A method of forming a semiconductor device, comprising:
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forming an anode electrode on one surface of a semiconductor substrate;
forming a plurality of ring-shaped trenches in the one surface of the semiconductor substrate, wherein centers, on the one surface of the semiconductor substrate, of each of the trenches form vertices of a triangular lattice;
forming a plurality of first Schottky contacts between the anode electrode and portions of the semiconductor substrate located inside the trenches; and
forming a plurality of second Schottky contacts between the anode electrode and portions of the semiconductor substrate located outside the trenches.
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Specification