Nitride-based semiconductor device and method of fabricating the same

• US 7,655,484 B2
• Filed: 04/26/2005
• Issued: 02/02/2010
• Est. Priority Date: 03/26/2002
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Toda, Tadao, Nomura, Yasuhiko, Hata, Masayuki, Yamaguchi, Tsutomu
• Primary Examiner(s): Nguyen; Thinh T
• Application Number:
  US11/114,193
• Publication Number:
  US 20050191775A1
• Time in Patent Office: 1,743 Days
• Field of Search: 438/663, 438/22, 438/706, 438/689, 438/669, 438/704, 257/104, 257/103, 257/105, 257/E33.025, 257/E33.028, 257/E33.033, 257/E21.006
• US Class Current: 438/22
• 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 the steps of:

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

removing dislocation defects at the back surface generated by the polishing until dislocation density at the back surface is not more than 1×

10⁹ cm<sup>−

2</sup>;

forming an n-side electrode on said back surface having the dislocation density of no more than 1×

10⁹ cm<sup>−

2</sup> with a contact resistance between the electrode and the back surface of no more than 0.05 ohms cm²; and

mounting said nitride-based semiconductor device in a junction-down system.

2. 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.

3. The method of fabricating a nitride-based semiconductor device according to claim 1,

further comprising a step of cleaving said first semiconductor layer.

7. The method of fabricating a nitride-based semiconductor device according to claim 1,

wherein the removing dislocation defects comprises etching with a combination of Cl₂ gas and BCI₃ gas followed by hydrochloric acid treatment.

9. The method of fabricating a nitride-based semiconductor device according to claim 1,

wherein the removing dislocation defects comprises wet etching.

15. The method of fabricating a nitride-based semiconductor device according to claim 1, further comprising cleaving said first semiconductor layer.

16. The method of fabricating a nitride-based semiconductor device according to claim 15,

further comprising etching the polished back surface prior to cleaving the first semiconductor layer.

4. A method of fabricating an n-type nitride-based semiconductor device, comprising the steps of:

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

removing dislocation defects at the back surface generated by the polishing until dislocation density at the back surface is not more than 1×

10⁹ cm<sup>−

2</sup>;

forming an n-side electrode on said back surface having the dislocation density of no more than 1×

10⁹ cm<sup>−

2</sup> with a contact resistance between the electrode and the back surface of no more than 0.05 ohms cm²; and

adhering between said n-side electrode and a radiator base.

5. The method of fabricating a nitride-based semiconductor device according to claim 4,

further comprising a step of performing heat treatment after said step of forming said n-side electrode.

6. The method of fabricating a nitride-based semiconductor device according to claim 4,

further comprising a step of cleaving said first semiconductor layer.

8. The method of fabricating a nitride-based semiconductor device according to claim 4,

wherein the removing dislocation defects comprises etching with a combination of Cl₂ gas and BCI₃ gas followed by hydrochloric acid treatment.

10. The method of fabricating a nitride-based semiconductor device according to claim 4,

wherein the removing dislocation defects comprises wet etching.

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

mechanically polishing the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or an n-type nitride-based semiconductor substrate having a wurtzite structure with an abrasive particle roughness of about 0.2 μ

m to about 1 μ

m;

etching the polished surface to remove a thickness of about 1 μ

m until a dislocation density at the back surface is not more than 1×

10 ⁹ cm<sup>−

2</sup>; and

forming an n-side electrode on the polished and etched back surface having the dislocation density of no more than 133 10⁹ cm² with a contact resistance between the electrode and the back surface of no more than 0.05 ohms cm².

12. The method of fabricating a nitride-based semiconductor device according to claim 11,

further comprising performing heat treatment after said forming said n-side electrode.

13. The method of fabricating a nitride- based semiconductor device according to claim 11,

further comprising cleaving said first semiconductor layer.

14. The method of fabricating a nitride-based semiconductor device according to claim 11,

wherein the etching of the polished surface comprises wet etching.