Structure and method for III-nitride device isolation
View Patent ↗Isolation of III-nitride devices may be performed with a dopant selective etch that provides a smooth profile with little crystal damage in comparison to previously used isolation techniques. The dopant selective etch may be an electro-chemical or photo-electro-chemical etch. The desired isolation area may be identified by changing the conductivity type of the semiconductor material to be etched. The etch process can remove a conductive layer to isolate a device atop the conductive layer. The etch process can be self stopping, where the process automatically terminates when the selectively doped semiconductor material is removed.
1. A method of fabricating a semiconductor device comprising:
forming said semiconductor device on a III-nitride semiconductor body;
identifying portions of said III-nitride semiconductor body as defining an isolation region of said semiconductor device;
selectively changing the conductivity type of said portions of said III-nitride semiconductor body from one conductivity type to another conductivity type after said forming; and
removing said portions of said III-nitride semiconductor body to produce said isolation region;
said removing of said portions being selective to said another conductivity type.
2. The method of claim 1 , wherein said III-nitride semiconductor body is GaN based.
3. The method of claim 1 , wherein said III-nitride semiconductor body is disposed over a body layer.
4. The method of claim 3 , wherein said body layer is comprised of at least one layer of a III-nitride material.
5. The method of claim 3 , wherein said body layer is comprised of silicon.
6. The method of claim 1 , wherein said body layer is comprised of silicon carbide.
7. The method of claim 1 , wherein said body layer is comprised of sapphire.
8. The method of claim 3 , wherein said body layer is comprised of a composite that includes graded III-nitride.
9. The method of claim 3 , wherein said body layer is conductive.
10. The method of claim 1 , wherein said body is comprised of a resistive material.
11. The method of claim 1 , wherein said body is comprised of an insulating material.
12. The method of claim 1 , wherein said semiconductor device is one of a FET, a Schottky diode, and a rectifier.
13. The method of claim 1 , wherein said selectively changing step is carried out through dopant implantation.
14. The method of claim 1 , wherein said removing step is carried out by an electrochemical etch.
15. The method of claim 1 , wherein said removing step is carried out by a photo electro-chemical etch.
16. The method of claim 1 , further comprising filling voids formed by said removing step with a dielectric material.
17. The method of claim 1 , further comprising passivating voids formed by said removing step.
18. A method comprising:
forming a III-nitride semiconductor device on a semiconductor material;
after said forming, selectively exposing a given surface area of said semiconductor material near said III-nitride semiconductor device, to dopant implantation, so as to change a conductivity type of said given surface area of said semiconductor material to another conductivity type;
applying a dopant selective etch to the semiconductor material to remove the semiconductor material exposed in said given surface area;
wherein removal of said semiconductor material exposed in said given surface area is selective to said another conductivity type.
19. The method according to claim 18 , wherein the etch is an electro-chemical etch.
20. The method according to claim 18 , wherein the etch is a photo-electro chemical etch.