Substrate regeneration method and regenerated substrate

Patent metadata

Field	Value
Publication number	US-9859108-B2
Application number	US-201514958793-A
Country	US
Kind code	B2
Filing date	Dec 3, 2015
Priority date	Jun 3, 2013
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

Disclosed are a substrate regeneration method and a regenerated substrate. The substrate regeneration method comprises preparing a substrate having a surface separated from an epitaxial layer. The separated surface includes a convex portion and a concave portion, and the convex portion is comparatively flatter than the concave portion. A crystalline restoration layer is grown on the separated surface. The crystalline restoration layer is grown on the convex portion. Furthermore, a surface roughness improvement layer is grown on the crystalline restoration layer, thereby providing a continuous surface. Accordingly, it is possible to provide a regenerated substrate, which has a flat surface, without using physical polishing or chemical etching technology.

First claim

The invention claimed is:

1. A substrate recycling method comprising:
preparing a substrate having a surface separated from an epitaxial layer such that the separated surface comprises a convex portion and a concave portion, the convex portion being flatter than the concave portion;
growing a crystallinity restoring layer on the separated surface such that the crystallinity restoring layer is grown on the convex portion and forms a first cavity on an upper portion of the concave portion; and
growing a surface roughness improving layer on the crystallinity restoring layer to have a continuous surface,
wherein the preparing of the substrate includes performing two stages of electrochemical etching (ECE) with different voltages from each other to form a sacrificial layer.

2. The substrate recycling method according to claim 1 , wherein the crystallinity restoring layer and the surface roughness improving layer are grown as gallium nitride-based semiconductor layers, and the surface roughness improving layer is grown at a higher temperature and a lower pressure than the crystallinity restoring layer.

3. The substrate recycling method according to claim 2 , wherein the crystallinity restoring layer is grown at a temperature of 1000° C. to 1060° C. and a pressure of 300 Torr to 500 Torr in a V/III composition ratio of 200 to 400, and the surface roughness improving layer is grown at a temperature of 1080° C. to 1140° C. and a pressure of 100 Torr to 200 Torr in a V/III composition ratio of 50 to 250.

4. The substrate recycling method according to claim 3 , wherein the crystallinity restoring layer and the surface roughness improving layer are formed of undoped GaN.

5. The substrate recycling method according to claim 1 , wherein the sacrificial layer is formed on the surface of the substrate, the convex portion and the concave portion are formed on the sacrificial layer, and the crystallinity restoring layer is directly formed on the sacrificial layer.

6. The substrate recycling method according to claim 5 , wherein the substrate having the surface separated from the epitaxial layer further comprises an anti-etching layer at a lower portion of the sacrificial layer to prevent electrochemical etching.

7. The substrate recycling method according to claim 6 , wherein the sacrificial layer comprises a gallium nitride-based semiconductor layer doped with an n-type dopant, and the anti-etching layer comprises an undoped gallium nitride-based semiconductor layer.

8. The substrate recycling method according to claim 1 , wherein the crystallinity restoring layer is grown in a thickness direction and a lateral direction, the growing in the lateral direction proceeding over an upper portion of the concave portion.

9. The substrate recycling method according to claim 8 , wherein the first cavity is formed on an upper portion of the concave portion and under the crystallinity restoring layer such that the first cavity is surrounded by the surface of the substrate and the crystallinity restoring layer.

10. The substrate recycling method according to claim 9 , wherein a second cavity is formed above the first cavity to be surrounded by the crystallinity restoring layer.

11. The substrate recycling method according to claim 1 , wherein the convex portion is formed in a stripe shape, an island shape, or a mesh shape.

12. The substrate recycling method according to claim 1 , wherein the substrate having the surface separated from the epitaxial layer comprises a lower substrate disposed under the separated surface, and the lower substrate is a gallium nitride substrate.

13. A recycled substrate comprising:
a lower substrate;
a sacrificial layer disposed on the lower substrate and having a first horizontal surface near the lower substrate and a second surface away from the lower substrate, and wherein the second surface includes a convex portion and a concave curved portion;
a crystallinity restoring layer disposed on the sacrificial layer; and
a surface roughness improving layer disposed on the crystallinity restoring layer and having a continuous surface;
wherein the crystallinity restoring layer covers the convex portion and the concave portion of the sacrificial layer to form a first cavity on the concave portion; and
wherein the crystallinity restoring layer has a second cavity extending from, and less than entirety of, the first cavity therein.

14. The recycled substrate according to claim 13 , wherein the sacrificial layer comprises a gallium nitride-based semiconductor layer doped with an n-type dopant.

15. The recycled substrate according to claim 14 , further comprising: an anti-etching layer disposed between the lower substrate and the sacrificial layer.

16. The recycled substrate according to claim 15 , wherein the anti-etching layer comprises an undoped gallium nitride-based semiconductor layer.

17. The recycled substrate according to claim 13 , wherein the crystallinity restoring layer and the surface roughness improving layer are undoped gallium nitride-based semiconductor layers.

18. The recycled substrate according to claim 13 , further comprising:
a second sacrificial layer disposed on the surface roughness improving layer and having a convex portion and a concave portion;
a second crystallinity restoring layer disposed on the second sacrificial layer; and
a second surface roughness improving layer disposed on the second crystallinity restoring layer and having a continuous surface.

19. The recycled substrate according to claim 18 , wherein the second sacrificial layer comprises a gallium nitride-based semiconductor layer doped with an n-type dopant.

20. The method of claim 13 , wherein the crystallinity restoring layer is positioned between the sacrificial layer and the surface roughness improving layer.

Assignees

• Seoul Viosys Co Ltd

Inventors

• Han Chang Suk
• Kim Hwa Mok
• Ko Mi So
• Lee A Ram Cha
• Suh Daewoong

Classifications

• H10P14/278 Primary

  Pendeoepitaxy · CPC title

• H10P90/16 Primary

  by reclaiming or re-processing · CPC title

• H10P14/271

  characterised by the preparation of substrate for selective deposition · CPC title

• H10P14/276

  Lateral overgrowth · CPC title

• H10P14/3416

  Nitrides · CPC title