Schottky diode structure with enhanced breakdown voltage and method of manufacture
View Patent ↗In one embodiment, a Schottky diode structure comprises a Schottky barrier layer in contact with a semiconductor material through a Schottky contact opening. A conductive ring is formed adjacent the Schottky contact opening and is separated from the semiconductor material by a thin insulating layer. Another insulating layer is formed overlying the structure, and a contact opening is formed therein. The contact opening is wider than the Schottky contact opening and exposes portions of the conductive ring. A Schottky barrier metal is formed in contact with the semiconductor material through the Schottky contact opening, and is formed in further+contact with the conductive ring.
1. A Schottky diode structure comprising:
a region of a semiconductor material having a first major surface;
a first insulating layer formed overlying the first major surface and having an active area opening;
a second insulating layer formed overlying the first major surface at least within the active area opening, wherein the second insulating layer has a Schottky contact opening that is smaller than the active area opening;
a conductive plate formed overlying the second insulating layer;
a third insulating layer formed overlying the conductive plate, wherein the third insulating layer has a contact opening overlying the Schottky contact opening and that is smaller than the active area opening and larger than the Schottky contact opening;
a metal layer contacting the region of the semiconductor material to form a Schottky barrier, the metal layer further contacting horizontal and vertical surfaces of the conductive plate;
a cathode contact coupled to the region of the semiconductor material at the first major surface; and
a doped region of the second conductivity type formed in the region of the semiconductor material adjoining the cathode contact, wherein the structure is formed absent a guard ring structure adjacent the Schottky barrier.
2. The structure of claim 1 further comprising a semiconductor substrate of a first conductivity type, and wherein the region of the semiconductor material is formed within the semiconductor substrate, and wherein the region of the semiconductor material comprises a second conductivity type.
3. The structure of claim 1 , wherein the conductive plate comprises a doped polysilicon ring.
4. The structure of claim 1 , wherein the metal layer comprises aluminum.
5. The structure of claim 1 , wherein the first insulating layer has a thickness from about 0.05 microns to about 0.5 microns.
6. A Schottky barrier structure comprising:
a semiconductor region of a first conductivity type having a first major surface;
a first insulating layer formed overlying the first major surface and having an active area opening;
a second insulating layer formed overlying the first major surface within the active area opening, wherein the second insulating layer has a Schottky contact opening that is smaller than the active area opening;
a conductive ring formed overlying the second insulating layer;
a third insulating layer formed overlying the conductive layer, wherein the third insulating layer has a contact opening overlying the Schottky contact opening and that is smaller than the active area opening and larger than the Schottky contact opening;
a metal layer contacting the semiconductor region through the Schottky contact opening and contacting the conductive ring through the contact opening, wherein the conductive ring is configured to enhance reverse breakdown voltage of the Schottky barrier structure , and wherein the structure is formed absent a guard ring structure adjacent the Schottky barrier; and
a cathode contact layer coupled to the semiconductor region at the first major surface.
7. The structure of claim 6 , wherein the conductive layer comprises doped polysilicon.
8. The structure of claim 6 , wherein the first insulating layer has a thickness from about 0.05 microns to about 0.5 microns.
9. The structure of claim 6 , wherein the semiconductor region is formed within a semiconductor substrate of a second conductivity type, and wherein the semiconductor region comprises a well region.
10. The structure of claim 9 further comprising a buried layer of the first conductivity type formed adjacent the well region.
11. The structure of claim 6 , wherein the contact metal layer contacts horizontal and vertical surfaces of the conductive ring.
12. The structure of claim 6 , wherein the metal layer comprises aluminum.