Method for forming a schottky diode on a silicon carbide substrate
A method for manufacturing a vertical Schottky diode with a guard ring on a lightly-doped N-type silicon carbide layer, including forming a P-type epitaxial layer on the N-type layer; implanting N-type dopants in areas of the P-type epitaxial layer to neutralize in these areas, across the entire thickness of the epitaxial layer, the P-type dopants to form N-type regions, of dopant concentration lower than that of the epitaxial layer, and delimiting a P-type guard ring; forming on the external periphery of the component an insulating layer partially covering the guard ring; and forming a Schottky contact with the N-type region internal to the guard ring.
1. A method for manufacturing a vertical Schottky diode with a guard ring on a lightly-doped N-type silicon carbide layer, comprising the steps of:
forming a P-type epitaxial layer on the N-type layer;
implanting N-type dopants in areas of the P-type epitaxial layer to neutralize P-type dopants in these areas, across an entire thickness of the epitaxial layer, to form N-type regions of dopant concentration lower than that of the epitaxial layer, the N-type regions delimiting a P-type guard ring;
forming on an external periphery of the epitaxial layer an insulating layer partially covering the guard ring; and
forming a Schottky contact with at least one of the N-type regions internal to the guard ring.
2. The method of claim 1 , wherein additional P-type regions located inside of the guard ring are delimited upon implantation of N-type dopants.
3. The component of claim 1 , wherein at least one additional ring located outside of the guard ring is delimited upon implantation of N dopants.
4. The method of claim 1 , further comprising the step of etching, prior to the implantation of N dopants, areas of the P-type epitaxial layer down to a depth smaller than the thickness of said epitaxial layer to form P-type protruding portions.
5. The method of claim 4 , wherein the guard ring is delimited to comprise a protruding portion located on its outer periphery.
6. The method of claim 5 , wherein the insulating layer covers the protruding portion of the guard ring.
7. The method of claim 4 , wherein N-type dopants are implanted in a protruding portion of the P-type epitaxial layer down to a depth smaller than the thickness of said portion to form N-type regions located on P-type regions.
8. A method of manufacturing a diode on an N-type silicon carbide layer, comprising acts of:
(A) forming a P-type epitaxial layer on the N-type layer;
(B) implanting N-type dopants in the epitaxial layer to form a plurality of N-type regions delimiting a P-type guard ring; and
(C) forming a Schottky contact that contacts at least one of the N-type regions within an area delimited by the guard ring.
9. The method of claim 8 , wherein acts (A)-(C) are performed such that the diode is a Schottky diode.
10. The method of claim 8 , wherein acts (A)-(C) are performed such that the diode is a Schottky/bipolar diode.
11. The method of claim 8 , further comprising an act of:
(D) forming on a periphery of a surface of the epitaxial layer an insulating layer that partially covers the guard ring, such that the Schottky contact only contacts a portion of the guard ring not partially covered by the insulating layer.
12. The method of claim 8 , wherein the act (A) comprises forming the epitaxial layer such that the epitaxial layer is more heavily-doped than the N-type layer.
13. The method of claim 8 , wherein the act (B) comprises forming the N-type regions such that the N-type regions are less heavily-doped than the guard ring.
14. The method of claim 8 , wherein the act (B) comprises forming the N-type regions such that at least two of the N-type regions delimit additional P-type regions within the area delimited by the guard ring.
15. The method of claim 8 , wherein the act (B) comprises forming the N-type regions such that at least two of the N-type regions delimit at least one additional P-type ring external to the area delimited by the guard ring.
16. The method of claim 8 , further comprising an act of:
(D) prior to performing act (B), etching at least one area of the epitaxial layer to reduce a distance that the at least one area extends perpendicularly from a surface of the N-type layer, such that at least one portion of the epitaxial layer extends further, perpendicularly, from the surface of the N-type layer than the at least one area.
17. The method of claim 8 , where the act (B) comprises forming the N-type regions such that the guard ring comprises the at least one portion.
18. The method of claim 8 , further comprising an act of:
(D) prior to performing act (B), forming a mask on the epitaxial region defining lateral dimensions of the N-type regions and the guard ring.