Nitride-based semiconductor device and method of fabricating the same

• US 20040012032A1
• Filed: 03/24/2003
• Published: 01/22/2004
• Est. Priority Date: 03/26/2002
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Nomura, Yasuhiko, Hata, Masayuki, Yamaguchi, Tsutomu, Toda, Tadao
• Granted Patent: US 6,791,120 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/28575 on semiconductor bodies comprising AIIIBV compounds
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/66462 with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 5/04252 characterised by the material
• CPC Class Codes: H01S 5/2201 in a specific crystallographic orientation
• CPC Class Codes: H01S 5/305 characterised by the doping materials used in the laser structure
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

A method of fabricating a nitride-based semiconductor device capable of reducing contact resistance between a nitrogen face of a nitride-based semiconductor substrate or the like and an electrode is provided. This method of fabricating a nitride-based semiconductor device comprises steps of etching the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or a nitride-based semiconductor substrate having a wurtzite structure and thereafter forming an n-side electrode on the etched back surface of the first semiconductor layer.

Claims

1. A method of fabricating a nitride-based semiconductor device, comprising steps of:

etching the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or a nitride-based semiconductor substrate having a wurtzite structure; and

thereafter forming an n-side electrode on said etched back surface of said first semiconductor layer.

2. The method of fabricating a nitride-based semiconductor device according to claim 1, wherein the back surface of said first semiconductor layer includes a nitrogen face of said first semiconductor layer.

3. The method of fabricating a nitride-based semiconductor device according to claim 1, wherein said etching step includes a step of etching the back surface of said first semiconductor layer by dry etching.

4. The method of fabricating a nitride-based semiconductor device according to claim 3, wherein said step of etching the back surface of said first semiconductor layer by dry etching includes a step of etching the back surface of said first semiconductor layer by reactive ion etching with Cl₂ gas and BCl₃ gas.

5. The method of fabricating a nitride-based semiconductor device according to claim 4, wherein the ratio of the flow rate of BCl₃ gas to the flow rate of Cl₂ gas in said step of etching the back surface of said first semiconductor layer by said reactive ion etching is at least 30% and not more than 70%.

6. The method of fabricating a nitride-based semiconductor device according to claim 3, wherein the etching depth and the etching time in said step of etching the back surface of said first semiconductor layer by said dry etching are proportional to each other.

7. The method of fabricating a nitride-based semiconductor device according to claim 1, wherein said etching step includes a step of etching the back surface of said first semiconductor layer thereby converting the back surface of said first semiconductor layer to a mirror surface.

8. The method of fabricating a nitride-based semiconductor device according to claim 1, further comprising a step of performing heat treatment after said step of forming said n-side electrode.

9. The method of fabricating a nitride-based semiconductor device according to claim 1, wherein said etching step includes a step of etching the back surface of said first semiconductor layer by a thickness of at least about 1 μ

m.

10. The method of fabricating a nitride-based semiconductor device according to claim 1, wherein said first semiconductor layer includes said n-type nitride-based semiconductor layer or said nitride-based semiconductor substrate consisting of at least one material selected from a group consisting of GaN, BN, AlN, InN and TlN.

11. The method of fabricating a nitride-based. semiconductor device according to claim 1, wherein said n-side electrode includes an Al film.

12. The method of fabricating a nitride-based semiconductor device according to claim 1, wherein said nitride-based semiconductor device is a nitride-based semiconductor light-emitting device.

13. The method of fabricating a nitride-based semiconductor device according to claim 1, further comprising a step of dipping a nitrogen face of said etched first semiconductor layer in a solution containing at least one of chlorine, fluorine, bromine, iodine, sulfur and ammonium in advance of said step of forming said n-side electrode.

14. The method of fabricating a nitride-based semiconductor device according to claim 13, further comprising a step of performing hydrochloric acid treatment on the back surface of said first semiconductor layer with an HCl solution in advance of said step of forming said n-side electrode.

15. The method of fabricating a nitride-based semiconductor device according to any of claims 1 to 8, further comprising a step of polishing the back surface of said first semiconductor layer in advance of said etching step.

16. The method of fabricating a nitride-based semiconductor device according to claim 1, wherein said etching step includes a step of etching the back surface of said first semiconductor layer by wet etching.

17. The method of fabricating a nitride-based semiconductor device according to claim 16, wherein said step of etching the back surface of said first semiconductor layer by wet etching includes a step of etching the back surface of said first semiconductor layer with at least one etchant selected from a group consisting of aqua regia, KOH and K₂S₂O_8.

18. The method of fabricating a nitride-based semiconductor device according to claim 16, wherein said step of etching the back surface of said first semiconductor layer by wet etching includes a step of etching the back surface of said first semiconductor layer while increasing the temperature to about 120°

C.

19. A method of fabricating a nitride-based semiconductor device, comprising steps of:

etching a nitrogen face of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or a nitride-based semiconductor substrate having a wurtzite structure by dry etching; and

thereafter forming an n-side electrode on said etched nitrogen face of said first semiconductor layer.

20. A nitride-based semiconductor device formed through steps of:

etching the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or a nitride-based semiconductor substrate having a wurtzite structure; and

thereafter forming an n-side electrode on said etched back surface of said first semiconductor layer.

21. A nitride-based semiconductor device comprising:

a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or a nitride-based semiconductor substrate having a wurtzite structure; and

an n-side electrode formed on the back surface of said first semiconductor layer, wherein

contact resistance between said n-side electrode and said first semiconductor layer is not more than 0.05 Ω

cm².

22. The nitride-based semiconductor device according to claim 21, wherein

an electron carrier concentration is at least 1×

10¹⁷ cm<sup>−

3</sup> in the vicinity of the interface between said first semiconductor layer and said n-side electrode.

23. The nitride-based semiconductor device according to claim 21, wherein

a dislocation density is not more than 1×

10⁹ cm<sup>−

2</sup> in the vicinity of the interface between said first semiconductor layer and said n-side electrode.

24. The nitride-based semiconductor device according to claim 21, wherein

the back surface of said first semiconductor layer includes a nitrogen face of said first semiconductor layer.

25. The nitride-based semiconductor device according to claim 21, wherein

said first semiconductor layer includes said n-type nitride-based semiconductor layer or said nitride-based semiconductor substrate consisting of at least one material selected from a group consisting of GaN, BN, AlN, InN and TlN.

26. The nitride-based semiconductor device according to claim 21, wherein

said n-side electrode includes an Al film.

27. The nitride-based semiconductor device according to claim 21, wherein

said nitride-based semiconductor device is a nitride-based semiconductor light-emitting device.