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A Schottky diode is disclosed that includes a silicon carbide substrate, a silicon carbide drift layer, a Schottky contact, and a passivation structure. The silicon carbide drift layer provides an active region and an edge termination region about the active region. The Schottky contact has sides an

A Schottky diode is disclosed that includes a silicon carbide substrate, a silicon carbide drift layer, a Schottky contact, and a passivation structure. The silicon carbide drift layer provides an active region and an edge termination region about the active region. The Schottky contact has sides and a top extending between the two sides and includes a Schottky layer over the active region and an anode contact over the Schottky layer. The passivation structure covers the edge termination region, the sides of the Schottky contact, and at least a portion of the top of the Schottky contact. The passivation structure includes a first silicon nitride layer, a silicon dioxide layer over the first silicon nitride layer, and a second silicon nitride layer over the silicon dioxide layer.

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1. A Schottky diode comprising: a silicon carbide substrate;a silicon carbide drift layer over the silicon carbide substrate and providing an active region and an edge termination region about the active region;a Schottky contact having sides and a top extending between the sides and comprising a Sc

1. A Schottky diode comprising: a silicon carbide substrate;a silicon carbide drift layer over the silicon carbide substrate and providing an active region and an edge termination region about the active region;a Schottky contact having sides and a top extending between the sides and comprising a Schottky layer over the active region and an anode contact over the Schottky layer; anda passivation structure comprising a first silicon nitride layer, a silicon dioxide layer over the first silicon nitride layer, and a second silicon nitride layer over the silicon dioxide layer, wherein the first silicon nitride layer, the silicon dioxide layer, and the second silicon nitride layer are plasma enhanced chemical vapor deposition layers such that a thickness of the first silicon nitride layer is greater than a thickness of the second silicon nitride layer and the passivation structure covers the edge termination region, the sides of the Schottky contact, and at least a portion of the top of the Schottky contact. 2. The Schottky diode of claim 1 further comprising an oxide layer between the passivation structure and the silicon carbide drift layer and extending outward from the sides of the Schottky contact over the edge termination region. 3. The Schottky diode of claim 2 wherein the oxide layer does not cover the top of the Schottky contact and portions of the sides of the Schottky contact that extend above the oxide layer. 4. The Schottky diode of claim 3 wherein the oxide layer is a thermally grown silicon dioxide layer. 5. The Schottky diode of claim 2 wherein the oxide layer is a thermally grown silicon dioxide layer. 6. The Schottky diode of claim 1 further comprising a cathode contact on a bottom side of the silicon carbide substrate opposite the silicon carbide drift layer. 7. The Schottky diode of claim 1 wherein the Schottky contact further comprises a tantalum barrier layer between the anode contact and the Schottky layer. 8. The Schottky diode of claim 1 further comprising an encapsulation layer over the passivation structure. 9. The Schottky diode of claim 8 wherein the encapsulation layer is a polyimide layer. 10. The Schottky diode of claim 1 wherein the thickness of the second silicon nitride layer is greater than a thickness of the silicon dioxide layer. 11. The Schottky diode of claim 1 wherein the thickness of the first silicon nitride layer is between about 6400 and 9600 Angstroms, a thickness of the silicon dioxide layer is between about 900 and 1100 Angstroms, and the thickness of the second silicon nitride layer is between about 2400 and 3600 Angstroms. 12. The Schottky diode of claim 11 wherein an index of refraction for the first silicon nitride layer is between about 1.95 and 2.15, an index of refraction for the silicon dioxide layer is between about 1.45 and 1.5, and an index of refraction for the second silicon nitride layer is between about 1.95 and 2.15. 13. The Schottky diode of claim 1 wherein an index of refraction for the first silicon nitride layer is between about 1.95 and 2.15, an index of refraction for the silicon dioxide layer is between about 1.45 and 1.5, and an index of refraction for the second silicon nitride layer is between about 1.95 and 2.15. 14. The Schottky diode of claim 1 further comprising an oxide layer that extends outward from the sides of the Schottky contact over the edge termination region, and wherein for the passivation structure, the first silicon nitride layer is directly on the oxide layer, the silicon dioxide layer is directly on the first silicon nitride layer, and the second silicon nitride layer is directly on the silicon dioxide layer. 15. The Schottky diode of claim 14 wherein the oxide layer is a thermally grown silicon dioxide layer that does not cover the top of the Schottky contact and portions of the sides of the Schottky contact that extend above the silicon dioxide layer. 16. The Schottky diode of claim 1 wherein the Schottky diode has a rated reverse breakdown voltage and can operate at 80% of the rated reverse breakdown voltage, at 85% humidity, and at 85 Celsius for at least 1000 hours without failing. 17. The Schottky diode of claim 1 wherein the Schottky diode has a rated reverse breakdown voltage of at least 600 V. 18. A method for fabricating a Schottky diode comprising: providing a silicon carbide substrate with a silicon carbide drift layer over the silicon carbide substrate, the silicon carbide drift layer having an active region and an edge termination region about the active region;forming a Schottky contact over the active region, the Schottky contact having sides and a top extending between the sides and comprising a Schottky layer over the active region and an anode contact over the Schottky layer; andforming a passivation structure comprising a first silicon nitride layer, a silicon dioxide layer over the first silicon nitride layer, and a second silicon nitride layer over the silicon dioxide layer, wherein the first silicon nitride layer, the silicon dioxide layer, and the second silicon nitride layer are plasma enhanced chemical vapor deposition layers such that a thickness of the first silicon nitride layer is greater than a thickness of the second silicon nitride layer and the passivation structure covers the edge termination region, the sides of the Schottky contact, and at least a portion of the top of the Schottky contact. 19. The method of claim 18 wherein the first silicon nitride layer, the silicon dioxide layer, and the second silicon nitride layer are successively formed during a single plasma enhanced chemical vapor deposition process. 20. The method of claim 18 further comprising forming an oxide layer that extends outward from the sides of the Schottky contact over the edge termination region prior to forming the passivation structure. 21. The method of claim 20 wherein the oxide layer does not cover the top of the Schottky contact and portions of the sides of the Schottky contact that extend above the oxide layer. 22. The method of claim 21 wherein the oxide layer is a thermally grown silicon dioxide layer. 23. The method of claim 20 wherein the oxide layer is a thermally grown silicon dioxide layer. 24. The method of claim 18 further comprising forming a cathode contact on a bottom side of the silicon carbide substrate opposite the silicon carbide drift layer. 25. The method of claim 24 wherein the thickness of the first silicon nitride layer is greater than a thickness of the silicon dioxide layer. 26. The method of claim 18 wherein the thickness of the first silicon nitride layer is between about 6400 and 9600 Angstroms, a thickness of the silicon dioxide layer is between about 900 and 1100 Angstroms, and the thickness of the second silicon nitride layer is between about 2400 and 3600 Angstroms. 27. The method of claim 26 wherein an index of refraction for the first silicon nitride layer is between about 1.95 and 2.15, an index of refraction for the silicon dioxide layer is between about 1.45 and 1.5, and an index of refraction for the second silicon nitride layer is between about 1.95 and 2.15. 28. The method of claim 18 wherein the Schottky diode has a rated reverse breakdown voltage and can operate at 80% of the rated reverse breakdown voltage, at 85% humidity, and at 85 Celsius for at least 1000 hours without failing. 29. The method of claim 18 wherein the Schottky diode has a rated reverse breakdown voltage of at least 600 V. 30. The method of claim 18 further comprising forming a polyimide layer over the passivation structure. 31. The method of claim 18 further comprising forming an oxide layer that extends outward from the sides of the Schottky contact over the edge termination region prior to forming the passivation structure, and wherein the first silicon nitride layer is directly on the oxide layer, the silicon dioxide layer is directly on the first silicon nitride layer, and the second silicon nitride layer is directly on the silicon dioxide layer. 32. The method of claim 18 wherein the oxide layer is a thermally grown silicon dioxide layer that does not cover the top of the Schottky contact and portions of the sides of the Schottky contact that extend above the silicon dioxide layer. 33. The method of claim 18 wherein the thickness of the second silicon nitride layer is greater than a thickness of the silicon dioxide layer. 34. The method of claim 18 wherein an index of refraction for the first silicon nitride layer is between about 1.95 and 2.15, an index of refraction for the silicon dioxide layer is between about 1.45 and 1.5, and an index of refraction for the second silicon nitride layer is between about 1.95 and 2.15. 35. The method of claim 18 further comprising forming a tantalum barrier layer between the anode contact and the Schottky layer.