GaN SINGLE-CRYSTAL SUBSTRATE, NITRIDE TYPE SEMICONDUCTOR EPITAXIAL SUBSTRATE, NITRIDE TYPE SEMICONDUCTOR DEVICE, AND METHODS OF MAKING THE SAME

• US 20100173483A1
• Filed: 03/16/2010
• Published: 07/08/2010
• Est. Priority Date: 05/13/2002
• Status: Abandoned Application

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Chua, Soo-Jin, Ueno, Masaki, Chen, Peng, Takasuka, Eiryo
• Application Number:
  US12/725,233
• Publication Number:
  US 20100173483A1
• Time in Patent Office: Days
• US Class Current: 438/509
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 21/3245 of AIIIBV compounds
• CPC Class Codes: H01L 21/3247 for altering the shape, e.g. smoothing the surface

Abstract

The GaN single-crystal substrate 11 in accordance with the present invention has a polished surface subjected to heat treatment for at least 10 minutes at a substrate temperature of at least 1020° C. in a mixed gas atmosphere containing at least an NH₃ gas. As a consequence, an atomic rearrangement is effected in the surface of the substrate 11 in which a large number of minute defects are formed by polishing, so as to flatten the surface of the substrate 11. Therefore, the surface of an epitaxial layer 12 formed on the substrate 11 can be made flat.

Claims

1-20. -20. (canceled)

21. A method of making a nitride type semiconductor epitaxial substrate, the method comprising steps of:

subjecting a GaN single-crystal having a polished surface to heat treatment for at least 10 minutes at a substrate temperature of at least 1020°

C. in a mixed gas atmosphere containing at least a NH₃ gas and a H₂ gas, said surface of said GaN single-crystal substrate having a root-mean-square roughness of 0.2 nm or less; and

epitaxially growing a nitride compound semiconductor layer, on said GaN single-crystal substrate, said GaN single-crystal substrate being obtained without oxidizing said surface of said GaN single-crystal substrate, and said nitride compound semiconductor layer having a surface with a root-mean-square roughness of 0.2 nm or less,

wherein both said epitaxial growth and said heat treatment of said GaN single-crystal substrate are effected within a reactor for carrying out said epitaxial growth,

the nitride compound is of the general formula Al_xIn_yGa_1-x-yN, and

0≦

X≦

1, 0≦

Y≦

1 and 0≦

X+Y≦

1.

22. The method according to claim 21, wherein said surface of said GaN single-crystal substrate is mechanical polished.

23. The method according to claim 21, said method comprising the step of:

carrying out mechanical polishing of a GaN single-crystal article to form the polished surface of the GaN single-crystal.

24. The method according to claim 23, wherein the root-mean-square roughness of the heat-treated surface is smaller than that of the mechanical polished surface.

25. The method according to claim 21, wherein said nitride compound semiconductor layer has an x-ray diffraction half width of 100 seconds or less.

26. The method according to claim 21, wherein said nitride compound semiconductor layer has a threading dislocation density of 1×

10⁶ cm<sup>−

2</sup> or less.

27. The method according to claim 22, wherein a plurality of defects are formed in said GaN single crystal substrate by mechanical polishing such that the substrate surface, after mechanical polishing, has an Rms (root-mean-square roughness) of about 1.0 nm.