III nitride crystal substrate, and light-emitting device and method of its manufacture

• US 8,546,166 B2
• Filed: 11/28/2008
• Issued: 10/01/2013
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Fujiwara, Shinsuke, Yoshida, Hiroaki
• Primary Examiner(s): REAMES, MATTHEW L
• Application Number:
  US12/324,897
• Publication Number:
  US 20090140287A1
• Time in Patent Office: 1,768 Days
• Field of Search: 257/103, 257/79, 257/E29.089, 438/47
• US Class Current: 438/47
• CPC Class Codes: C30B 19/02 using molten solvents, e.g. flux
• CPC Class Codes: C30B 23/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02625 using melted materials
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 29/32 the imperfections being within the semiconductor body
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities

Abstract

Toward making available III nitride crystal substrates advantageously employed in light-emitting devices, and light-emitting devices incorporating the substrates and methods of manufacturing the light-emitting devices, a III nitride crystal substrate has a major face whose surface area is not less than 10 cm² and, in a major-face principal region excluding the peripheral margin of the major face from its outer periphery to a 5 mm separation from its outer periphery, the total dislocation density is from 1×10⁴ cm⁻² to 3×10⁶ cm⁻², and the ratio of screw-dislocation density to the total dislocation density is 0.5 or greater.

Claims

1. A III-nitride crystal substrate manufacturing method, comprising:

a step of preparing a starting undersubstrate including a III nitride crystal layer having a major face, with the major face having a predetermined angle of inclination of from 0.5°

to 10°

with respect to a {0001} plane of the III nitride crystal layer;

a step of forming on the major face of the starting undersubstrate a plurality of micro-steps consisting of a plurality of terraced faces paralleling the {0001} plane, and of a plurality of stepped planes having a predetermined angle with respect to the {0001} plane;

a step of initially growing III nitride crystal to a predetermined thickness by a liquid-phase technique onto the major face of the starting undersubstrate;

a step of additionally growing III nitride crystal onto the liquid-phase grown III-nitride crystal; and

a step of slicing the additionally grown III-nitride crystal through a plane paralleling the {0001} plane to produce a III-nitride crystal substrate;

wherein

said inclination of, and the form of said micro-steps on, the starting undersubstrate major face are predetermined such that in a major-face principal region of the III-nitride crystal substrate excluding the peripheral margin from the outer periphery of the major face to a 5 mm separation from the outer periphery, the substrate has a total density of screw dislocations, edge dislocations, and mixed screw-and-edge dislocations of between 1×

10⁴ cm<sup>−

2</sup> and 5×

10⁵ cm<sup>−

2</sup> inclusive, and has a ratio of screw-dislocation density to said total dislocation density of not less than 0.5.

3. A light-emitting device manufacturing method, comprising:

the III-nitride crystal substrate manufacturing method of claim 1; and

a step of forming an at least single-lamina III nitride layer onto the III nitride crystal substrate.

5. The III-nitride crystal substrate manufacturing method as set forth in claim 1, further comprising a step in between said steps of initially and additionally growing III-nitride crystal, of planarizing the liquid-phase grown III-nitride crystal to form thereon a major face paralleling the {0001} plane of the III nitride crystal layer on the starting undersubstrate;

wherein

in said step of additionally growing III nitride crystal, the growth is by a vapor-phase technique.

2. A III-nitride crystal substrate manufacturing method, comprising:

a step of preparing a starting undersubstrate including a III nitride crystal layer having a major face, with the major face having a predetermined angle of inclination of from 0.5°

to 10°

with respect to a {0001} plane of the III nitride crystal layer;

a step of forming on the major face of the starting undersubstrate a plurality of micro-steps consisting of a plurality of terraced faces paralleling the {0001} plane, and of a plurality of stepped planes having a predetermined angle with respect to the {0001} plane; and

a step of initially growing III nitride crystal to a predetermined thickness by a liquid-phase technique onto the major face of the starting undersubstrate;

a step of additionally growing III nitride crystal onto the liquid-phase grown III-nitride crystal; and

a step of slicing the additionally grown III-nitride crystal through a plane paralleling the {0001} plane to produce a III-nitride crystal substrate;

wherein

said inclination of, and the form of said micro-steps on, the starting undersubstrate major face are predetermined such that in a major-face principal region of the III-nitride crystal substrate excluding the peripheral margin from the outer periphery of the major face to a 5 mm separation from the outer periphery, the substrate has a total density of screw dislocations, edge dislocations, and mixed screw-and-edge dislocations of between 1×

10⁴ cm<sup>−

2</sup> and 5×

10⁵ cm<sup>−

2</sup> inclusive, and has a ratio of screw-dislocation density to said total dislocation density of not less than 0.9.

4. A light-emitting device manufacturing method, comprising:

the III-nitride crystal substrate manufacturing method of claim 2; and

a step of forming an at least single-lamina III nitride layer onto the III nitride crystal substrate.

6. The III-nitride crystal substrate manufacturing method as set forth in claim 2, further comprising a step in between said steps of initially and additionally growing III-nitride crystal, of planarizing the liquid-phase grown III-nitride crystal to form thereon a major face paralleling the {0001} plane of the III nitride crystal layer on the starting undersubstrate;

wherein

in said step of additionally growing III nitride crystal, the growth is by a vapor-phase technique.