Schottky device and method of manufacture
A Schottky device includes a barrier height adjustment layer in a portion of a semiconductor material. In accordance with an embodiment, the Schottky device is formed from a semiconductor material of a first conductivity type which has a barrier height adjustment layer of a second conductivity type that extends from a first major surface of the semiconductor material into the semiconductor material a distance that is less than a zero bias depletion boundary. A Schottky contact is formed in contact with the doped layer.
1. A Schottky device, comprising:
a semiconductor material of a first conductivity type having first and second major surfaces;
a layer of in-situ doped polysilicon over the semiconductor material;
a doped region of a second conductivity type extending from the first major surface a distance that is less than a depth of a zero bias depletion boundary, wherein an impurity material for the doped region is derived from the layer of in-situ doped polysilicon over the semiconductor material; and
a Schottky contact in contact with the doped region.
2. The Schottky device of claim 1 , wherein the semiconductor material comprises a semiconductor substrate and an epitaxial layer, the epitaxial layer on the semiconductor substrate.
3. The Schottky device of claim 1 , further including a plurality of trenches extending from the major surface into the semiconductor material.
4. The Schottky device of claim 3 , wherein the plurality of trenches extend into the semiconductor material a distance that is greater than the zero bias depletion boundary.
5. The Schottky device of claim 3 , wherein the plurality of trenches includes a first trench having floor and sidewalls, a dielectric material on the floor and sidewalls and a semiconductor material on the dielectric material.
6. The Schottky device of claim 1 , wherein a total integrated charge of the doped region is the integral of a doping concentration of the doped region over the distance that the doped region extends into the semiconductor material.
7. The Schottky device of claim 1 , wherein the Schottky contact comprises a silicide and a layer of electrically conductive material.
8. A method for manufacturing a Schottky device, comprising:
providing a semiconductor material of a first conductivity type having first and second major surfaces;
forming a barrier height adjustment layer of a second conductivity in the semiconductor material, the barrier height adjustment layer extending from the first major surface into the semiconductor material a distance that is less than a depth of a zero bias depletion boundary, wherein forming the barrier height adjustment layer comprises:
forming a layer of in-situ doped polysilicon over the semiconductor material; and
using the layer of in-situ doped polysilicon as a source of impurity material for the barrier height adjustment layer; and
forming a Schottky contact with the barrier height adjustment layer.
9. The method of claim 8 , wherein forming the barrier height adjustment layer comprises forming the barrier height adjustment layer before forming the Schottky contact.
10. The method of claim 8 , wherein forming the barrier height adjustment layer comprises forming the barrier height adjustment layer after forming the Schottky contact.
11. The method of claim 8 , wherein forming the barrier height adjustment layer comprises implanting an impurity material of the second conductivity type into the semiconductor material before forming the Schottky contact.
12. A method for manufacturing a Schottky device, comprising:
providing a semiconductor material of a first conductivity type having first and second major surfaces;
forming a barrier height adjustment layer of a second conductivity in the semiconductor material, the barrier height adjustment layer extending from the first major surface into the semiconductor material a distance that is less than a depth of a zero bias depletion boundary, wherein forming the barrier height adjustment layer comprises:
forming a layer of dielectric material over the semiconductor material;
forming a layer of polysilicon over the layer of dielectric material;
implanting an impurity material of the second conductivity type into the layer of polysilicon; and
using the impurity material implanted into the layer of polysilicon as a source of impurity material for the barrier height adjustment layer; and
forming a Schottky contact with the barrier height adjustment layer.
13. A method for manufacturing a Schottky device, comprising:
providing a semiconductor material of a first conductivity type having first and second major surfaces;
forming a barrier height adjustment layer of a second conductivity in the semiconductor material, the barrier height adjustment layer extending from the first major surface into the semiconductor material a distance that is less than a depth of a zero bias depletion boundary, wherein forming the barrier height adjustment layer comprises:
forming a silicide layer from the semiconductor material;
forming a layer of aluminum over the silicide layer; and
using the layer of aluminum as a source of impurity material for the barrier height adjustment layer; and
forming a Schottky contact with the barrier height adjustment layer.
14. A method for manufacturing a Schottky device, comprising:
providing a semiconductor material of a first conductivity type having first and second major surfaces;
forming a doped region of a second conductivity type in the semiconductor material, the doped region of the second conductivity type extending from the major surface into the semiconductor material a distance that is less than a depth of a zero bias depletion width, wherein forming the doped region of the second conductivity type comprises:
forming a layer of dielectric material over the semiconductor material;
forming a layer of polysilicon over the layer of dielectric material;
doping the layer of polysilicon with an impurity material of the second conductivity type; and
using the impurity material that dopes the layer of polysilicon as a source of impurity material for the barrier height adjustment layer; and
forming a Schottky contact to the doped region of the second conductivity type.
15. The method of claim 14 , wherein forming the doped region includes forming the doped region to have a total integrated charge equal to the integral of a doping concentration of the doped region over the distance that the doped region extends into the semiconductor material.
16. The method of claim 14 , wherein forming the doped region includes forming the doped region using a technique selected from the group of techniques comprising an ion implantation technique, a diffusion technique, and a plasma doping technique.
17. The method of claim 16 , wherein forming the doped region includes implanting an impurity material of the second conductivity through portions of the Schottky contact.