Method of fabricating a gallium nitride merged P-i-N Schottky (MPS) diode
View Patent ↗A semiconductor structure includes a III-nitride substrate with a first side and a second side opposing the first side. The III-nitride substrate is characterized by a first conductivity type and a first dopant concentration. The semiconductor structure also includes a III-nitride epitaxial structure including a first III-nitride epitaxial layer coupled to the first side of the III-nitride substrate and a plurality of III-nitride regions of a second conductivity type. The plurality of III-nitride regions have at least one III-nitride epitaxial region of the first conductivity type between each of the plurality of III-nitride regions. The semiconductor structure further includes a first metallic structure electrically coupled to one or more of the plurality of III-nitride regions and the at least one III-nitride epitaxial region. A Schottky contact is created between the first metallic structure and the at least one III-nitride epitaxial region.
1. A method for fabricating a merged P-i-N Schottky (MPS) diode in gallium nitride (GaN) based materials, the method comprising:
providing a free-standing n-type GaN-based substrate having a first surface and a second surface;
forming an n-type GaN-based epitaxial layer coupled to the first surface of the free-standing n-type GaN-based substrate;
implanting a p-type dopant into the n-type GaN-based epitaxial layer to form a GaN-based structure having a plurality of implanted p-type GaN-based regions with at least one n-type GaN-based epitaxial region disposed between adjacent ones of the plurality of implanted p-type GaN-based regions; and
forming a first metallic structure electrically coupled to one or more of the plurality of implanted p-type GaN-based regions and the at least one n-type GaN-based epitaxial region, wherein a Schottky contact is created between the first metallic structure and the at least one n-type GaN-based epitaxial region.
2. The method of claim 1 further comprising forming a second metallic structure electrically coupled to the second surface of the free-standing n-type GaN-based substrate.
3. The method of claim 1 wherein the n-type GaN-based substrate is characterized by a first n-type dopant concentration and the n-type GaN-based epitaxial layer is characterized by a second n-type dopant concentration less than the first n-type dopant concentration.
4. The method of claim 1 wherein at least one of the plurality of implanted p-type GaN-based regions is configured to provide edge termination to the MPS diode.
5. The method of claim 1 wherein at least one of the plurality of implanted p-type GaN-based regions is configured to provide a junction termination extension to the MPS diode.
6. A method for fabricating an epitaxial structure, the method comprising:
providing a free-standing III-nitride substrate of a first conductivity type and a first dopant concentration having a first surface and a second surface;
forming a first III-nitride epitaxial layer of the first conductivity type and a second dopant concentration less than the first dopant concentration coupled to the first surface of the free-standing III-nitride substrate;
implanting a dopant of a second conductivity type into the first III-nitride epitaxial layer to form a plurality of implanted III-nitride regions of the second conductivity type with at least one III-nitride epitaxial structure of the first conductivity type between adjacent ones of the plurality of implanted III-nitride regions; and
forming a first metallic structure electrically coupled to one or more of the plurality of implanted III-nitride regions and the at least one III-nitride epitaxial structure, wherein a Schottky contact is created between the first metallic structure and the at least one III-nitride epitaxial structure.
7. The method of claim 6 further comprising forming a second metallic structure electrically coupled to the second surface of the III-nitride substrate.
8. The method of claim 6 wherein at least one of the plurality of implanted III-nitride regions is configured to provide edge termination to a semiconductor device.
9. The method of claim 6 wherein at least one of the plurality of implanted III-nitride regions is configured to provide a junction termination extension to a semiconductor device.
10. A method for fabricating a MPS diode in GaN based materials, the method comprising:
providing a free-standing n-type GaN-based substrate having a first surface and a second surface;
forming an n-type GaN-based epitaxial layer coupled to the first surface of the free-standing n-type GaN-based substrate;
forming a p-type GaN epitaxial layer coupled to the n-type GaN-based epitaxial layer;
removing at least a portion of the p-type GaN epitaxial layer to form a plurality of p-type GaN-based regions with predetermined spaces between each of the plurality of p-type GaN-based regions;
regrowing at least one n-type GaN-based regrown epitaxial region in the predetermined spaces between each of the plurality of p-type GaN-based regions; and
forming a first metallic structure electrically coupled to one or more of the plurality of p-type GaN-based regions and the at least one n-type GaN-based regrown epitaxial region, wherein a Schottky contact is created between the first metallic structure and the at least one n-type GaN-based regrown epitaxial region.
11. The method of claim 10 further comprising forming a second metallic structure electrically coupled to the second surface of the free-standing n-type GaN-based substrate.
12. The method of claim 10 wherein at least one of the plurality of p-type GaN-based regions is configured to provide edge termination to the MPS diode.
13. The method of claim 10 wherein at least one of the plurality of p-type GaN-based regions is configured to provide a junction termination extension to the MPS diode.
14. The method of claim 10 wherein the free-standing n-type GaN-based substrate is characterized by a first dopant concentration and the n-type GaN-based epitaxial layer is characterized by a second dopant concentration lower than the first dopant concentration.
15. A method for fabricating an epitaxial structure, the method comprising:
providing a free-standing III-nitride substrate of a first conductivity type having a first surface and a second surface;
forming a first III-nitride epitaxial layer of the first conductivity type coupled to the first surface of the free-standing III-nitride substrate;
forming a second III-nitride epitaxial layer of a second conductivity type coupled to the first III-nitride epitaxial layer;
removing at least a portion of the second III-nitride epitaxial layer to form a plurality of III-nitride regions with at least one predetermined space between each of the plurality of III-nitride regions;
regrowing at least one III-nitride epitaxial regrown structure of the first conductivity type in the at least one predetermined space; and
forming a first metallic structure electrically coupled to one or more of the plurality of III-nitride regions and the at least one III-nitride epitaxial regrown structure, wherein a Schottky contact is created between the first metallic structure and the at least one III-nitride epitaxial regrown structure.
16. The method of claim 15 further comprising forming a second metallic structure electrically coupled to the second surface of the III-nitride substrate.
17. The method of claim 15 wherein at least one of the plurality of III-nitride regions is configured to provide edge termination to a semiconductor device.
18. The method of claim 15 wherein at least one of the plurality of III-nitride regions is configured to provide a junction termination extension to a semiconductor device.