Method for the reuse of gallium nitride epitaxial substrates

• US 9,773,704 B2
• Filed: 06/22/2016
• Issued: 09/26/2017
• Est. Priority Date: 02/17/2012
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Holder, Casey O., Feezell, Daniel F., DenBaars, Steven P., Nakamura, Shuji
• Primary Examiner(s): Lee, Kyoung
• Application Number:
  US15/189,356
• Publication Number:
  US 20160307801A1
• Time in Patent Office: 461 Days
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/02389 Nitrides
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 21/02664 Aftertreatments planarisation in general H01L21/304
• CPC Class Codes: H01L 21/30612 Etching of AIIIBV compounds
• CPC Class Codes: H01L 21/30635 of AIIIBV compounds
• CPC Class Codes: H01L 21/7813 leaving a reusable substrate, e.g. epitaxial lift off
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 31/03044 comprising a nitride compounds, e.g. GaN
• CPC Class Codes: H01L 31/1856 comprising nitride compounds, e.g. GaN
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 5/0217 Removal of the substrate
• CPC Class Codes: H01S 5/183 having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
• CPC Class Codes: H01S 5/18341 Intra-cavity contacts
• CPC Class Codes: H01S 5/18347 : Mesa comprising active layer
• CPC Class Codes: H01S 5/187 : using Bragg reflection
• CPC Class Codes: H01S 5/2009 : by using electron barrier layers
• CPC Class Codes: H01S 5/34333 : with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
• CPC Class Codes: Y02E 10/544 : Solar cells from Group III-V materials
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

A method for the reuse of gallium nitride (GaN) epitaxial substrates uses band-gap-selective photoelectrochemical (PEC) etching to remove one or more epitaxial layers from bulk or free-standing GaN substrates without damaging the substrate, allowing the substrate to be reused for further growth of additional epitaxial layers. The method facilitates a significant cost reduction in device production by permitting the reuse of expensive bulk or free-standing GaN substrates.

Claims

1. A method for fabricating a device, comprising:

providing a III-nitride substrate;

growing one or more Indium Gallium Nitride (InGaN) sacrificial layers on or above the III-nitride substrate;

growing one or more III-nitride device layers on or above the InGaN sacrificial layers; and

selectively etching the InGaN sacrificial layers to separate the III-nitride device layers from the III-nitride substrate without substantially etching the III-nitride device layers or the III-nitride substrate, wherein the selectively etched InGaN sacrificial layers are crystal layers.

2. A device, comprising:

a III-nitride substrate;

one or more Indium Gallium Nitride (InGaN) sacrificial layers grown on or above the III-nitride substrate; and

one or more III-nitride device layers grown on or above the InGaN sacrificial layers;

wherein the InGaN sacrificial layers are selectively etched layers used to separate the III-nitride device layers from the III-nitride substrate without the III-nitride device layers or the III-nitride substrate being substantially etched, and the selectively etched layers are crystal layers.

3. The device of claim 2, wherein the device comprises an optoelectronic, electronic or thermoelectric device.

4. The device of claim 3, wherein the device comprises a light emitting diode, laser diode, photovoltaic cell or transistor.

5. The device of claim 2, wherein the III-nitride substrate is an epitaxy-ready bulk or free-standing III-nitride substrate.

6. The device of claim 2, wherein the III-nitride substrate is Gallium Nitride (GaN).

7. The device of claim 6, wherein the III-nitride substrate is polar, semipolar or nonpolar GaN.

8. The device of claim 2, wherein the III-nitride substrate is reusable after the III-nitride device layers are separated from the III-nitride substrate.

9. The device of claim 8, wherein the III-nitride substrate is processed after the III-nitride device layers are separated from the III-nitride substrate to prepare the III-nitride substrate for reuse.

10. The device of claim 2, wherein the III-nitride substrate has been previously used to grow a III-nitride device structure.

11. The device of claim 2, wherein the InGaN sacrificial layers are grown on an etched or etched and polished surface of the III-nitride substrate.

12. The device of claim 11, wherein the surface of the III-nitride substrate is epitaxy ready, with no difference in crystal quality, doping, and surface roughness as compared to a new epitaxy-ready III-nitride substrate.

13. The device of claim 11, wherein the surface of the III-nitride substrate has a surface roughness smoother than 1 nanometer (nm) root mean square (RMS) on an area of at least 10×

10 micrometers.

14. The device of claim 2, wherein the InGaN sacrificial layers are selectively etched layers used to separate the III-nitride device layers from the III-nitride substrate without the III-nitride device layers or the III-nitride substrate being damaged, such that performance of the III-nitride device layers is not degraded and the III-nitride substrate can be reused.

15. The device of claim 14, wherein the performance of the III-nitride device layers is not degraded after the III-nitride device layers are separated from the III-nitride substrate as compared to III-nitride device layers grown on a new or unused III-nitride substrate.

16. The device of claim 2, wherein the InGaN sacrificial layers are selectively etched laterally and are completely removed, thereby freeing the III-nitride substrate from the III-nitride device layers.

17. The device of claim 2, wherein the InGaN sacrificial layers are exposed before being selectively etched.

18. The device of claim 2, further comprising one or more epitaxial layers grown on or above the III-nitride substrate, wherein the InGaN sacrificial layers are grown on or above the epitaxial layers.

19. The device of claim 18, wherein a contact is made to the epitaxial layers grown underneath the InGaN sacrificial layers in order to aid in extraction of carriers during band-gap-selective photoelectrochemical etching.

20. The device of claim 2, wherein the III-nitride device layers are sub-mounted to a carrier substrate.

21. A device, comprising:

a III-nitride substrate;

one or more Indium Gallium Nitride (InGaN) sacrificial layers grown on or above the III-nitride substrate; and

one or more III-nitride device layers grown on or above the InGaN sacrificial layers;

wherein the III-nitride substrate is separated from the III-nitride device layers after the InGaN sacrificial layers are selectively etched, and the selectively etched InGaN sacrificial layers are crystal layers.