Self-standing GaN substrate, GaN crystal, method for producing GaN single crystal, and method for producing semiconductor device

• US 10,475,887 B2
• Filed: 02/05/2016
• Issued: 11/12/2019
• Est. Priority Date: 08/08/2013
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Nagao, Satoru, Tsukada, Yusuke, Kamada, Kazunori, Kubo, Shuichi, Ikeda, Hirotaka, Fujito, Kenji, Fujisawa, Hideo, Mikawa, Yutaka, Mochizuki, Tae
• Primary Examiner(s): Sheikh, Humera N
• Assistant Examiner(s): Ivey, Elizabeth D
• Application Number:
  US15/016,409
• Publication Number:
  US 20160233306A1
• Time in Patent Office: 1,376 Days
• CPC Class Codes: C30B 23/025 characterised by the substrate
• CPC Class Codes: C30B 25/186 being specially pre-treated by, e.g. chemical or physical means
• CPC Class Codes: C30B 25/20 the substrate being of the same materials as the epitaxial layer
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 7/105 using ammonia as solvent, i.e. ammonothermal processes
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 29/2003 Nitride compounds

Abstract

An object is to provide a nonpolar or semipolar GaN substrate having improved size and crystal quality. A self-standing GaN substrate has an angle between the normal of the principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein: the size of the projected image in a c-axis direction when the principal surface is vertically projected on an M-plane is 10 mm or more; and when an a-axis length is measured on an intersection line between the principal surface and an A-plane, a low distortion section with a section length of 6 mm or more and with an a-axis length variation within the section of 10.0×10⁻⁵ Å or less is observed.

Claims

1. A self-standing GaN substrate having a first principal surface and a second principal surface, the first principal surface and the second principal surface facing away from each other, and having an angle between a normal of the first principal surface and an m-axis of 0 degrees or more and 20 degrees or less, wherein:

a first projected image obtained by vertically projecting the first principal surface on an M-plane has a size of 10 mm or more in a c-axis direction; and

when an a-axis length is measured on an intersection line between the first principal surface and an A-plane, a first section having a section length of 6 mm or more and an a-axis length variation within the first section of 10.0×

10<sup>−

5</sup> Å

or less is observed.

2. The self-standing GaN substrate according to claim 1, wherein the size of the first projected image in a c-axis direction is 15 mm or more, and the first section has a section length of 8 mm or more and an a-axis length variation within the section of 10.0×

10<sup>−

5</sup> Å

or less.

3. The self-standing GaN substrate according to claim 2, wherein the first section has a section length of 10 mm or more and an a-axis length variation within the section of 10.0×

10<sup>−

5</sup> Å

or less.

4. The self-standing GaN substrate according to claim 3, wherein the first section has a section length of 10 mm or more and an a-axis length variation within the section of 8.0×

10<sup>−

5</sup> Å

or less.

5. The self-standing GaN substrate according to claim 1, wherein a c-axis length variation in the first section is 3.0×

10<sup>−

4</sup> Å

or less.

6. The self-standing GaN substrate according to claim 1, wherein an X-ray rocking curve full-width at half-maximum of a (300) plane in the first section is less than 100 arcsec.

7. The self-standing GaN substrate according to claim 1, wherein a variation width of an X-ray rocking curve full-width at half-maximum of a (300) plane in the first section is less than 20 arcsec.

8. The self-standing GaN substrate according to claim 1, having a defect increasing zone extending in a direction intersecting an A-plane on the first principal surface.

9. The self-standing GaN substrate according to claim 1, wherein a size of the first projected image in an a-axis direction is 30 mm or more.

10. The self-standing GaN substrate according to claim 1, wherein a size of the first projected image in an a-axis direction is 40 mm or more.

11. The self-standing GaN substrate according to claim 1, wherein the self-standing GaN substrate comprises a GaN crystal grown by an HVPE method.

12. The self-standing GaN substrate according to claim 1, having an absorption coefficient at a wavelength of 450 nm is 2 cm⁻

1 or less.

13. The self-standing GaN substrate according to claim 1 wherein the self-standing GaN substrate comprises fluorine.

14. The self-standing GaN substrate according to claim 1, having an alkali metal concentration of lower than 1×

10¹⁵ cm<sup>−

3</sup>.

15. The self-standing GaN substrate according to claim 1, wherein the self-standing GaN substrate comprises a stacking fault.