Structure and method for III-nitride device isolation

• US 8,748,204 B2
• Filed: 05/19/2006
• Issued: 06/10/2014
• Est. Priority Date: 12/05/2003
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Bridger, Paul
• Primary Examiner(s): Graybill, David E
• Application Number:
  US11/437,055
• Publication Number:
  US 20060223275A1
• Time in Patent Office: 2,944 Days
• Field of Search: None
• US Class Current: 438/46
• CPC Class Codes: H01L 21/7605 between components manufactured in an active substrate comprising AIII BV compounds
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264
• CPC Class Codes: H01L 21/764 Air gaps H01L21/76264 takes precedence

Abstract

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.

Claims

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.