SELF-STANDING GaN SUBSTRATE, GaN CRYSTAL, METHOD FOR PRODUCING GaN SINGLE CRYSTAL, AND METHOD FOR PRODUCING SEMICONDUCTOR DEVICE

• US 20190312111A1
• Filed: 06/18/2019
• Published: 10/10/2019
• 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
• Granted Patent: US 11,038,024 B2
• Time in Patent Office: 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 with 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

wherein the substrate produces an anomalous transmission image when subjected to transmission X-ray topography.

2. :

The self-standing GaN substrate according to claim 1, wherein the size of the projected image is a 10 mm square or more.

3. :

The self-standing GaN substrate according to claim 1, wherein the size of the projected image in a c-axis direction is 15 mm or more.

4. :

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

5. :

The self-standing GaN Substrate according to claim 1, wherein an absorption coefficient at a wavelength of 450 nm is 2 cm<sup>−

1</sup> or less.

6. :

The self-standing GaN substrate according to claim 1, wherein the self-standing GaN substrate contains fluorine.

7. :

The self-standing GaN substrate according to claim 1, wherein alkali metal concentration is lower than 1×

10¹⁵ cm<sup>−

3</sup>.

8. :

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

9. :

A method for manufacturing the self-standing GaN substrate according to claim 1, the method comprising;

an inspection step including transmission X-ray topography using anomalous transmission as a test item, wherein a product in which an unacceptable defect is found in the inspection step is deemed a defective product.

10. :

A method for manufacturing a GaN single crystal, the method comprising;

preparing the self-standing GaN substrate according to claim 1; and

epitaxially growing GaN on the self-standing GaN substrate.

11. :

A method for manufacturing a GaN single crystal, the method comprising;

growing a first GaN crystal using the self-standing GaN substrate according to claim 1 as a seed; and

subsequently,

growing a second GaN crystal using a part of or all of the first GaN crystal as a seed.

12. :

The method according to claim 10, which is a manufacturing method of a bulk GaN single crystal.

13. :

A method for manufacturing a semiconductor device, the method comprising;

preparing the self-standing GaN substrate according to claim 1; and

forming a device structure by epitaxially growing one or more types of nitride semiconductors on the self-standing GaN substrate.

14. :

A method for manufacturing a GaN layer-bonded substrate, the method comprising;

implanting ions in a vicinity of the principal surface of the self-standing GaN substrate according to claim 1;

bonding the principal surface side of the self-standing GaN substrate to a hetero-composition substrate; and

forming a GaN layer bonded to the hetero-composition substrate by separating the self-standing GaN substrate at the ion-implanted region as a boundary.

15. :

A GaN layer-bonded substrate comprising a structure in which a GaN layer separated from the self-standing GaN substrate according to claim 1 is bonded to a hetero-composition substrate.

16. :

The method according to claim 9, wherein the self-standing GaN substrate is a self-standing GaN substrate comprising a GaN crystal grown by an HVPE method.

17. :

The method according to claim 10, wherein the self-standing GaN substrate is a self-standing GaN substrate comprising a GaN crystal grown by an HVPE method.

18. :

The method according to claim 13, wherein the self-standing GaN substrate is a self-standing GaN substrate comprises a GaN crystal grown by an HVPE method.

19. :

The method according to claim 14, wherein the self-standing GaN substrate is a self-standing GaN substrate comprises a GaN crystal grown by an HVPE method.