Lift-off of epitaxial layers from silicon carbide or compound semiconductor substrates

Patent metadata

Field	Value
Publication number	US-9876081-B2
Application number	US-201414331440-A
Country	US
Kind code	B2
Filing date	Jul 15, 2014
Priority date	Jul 16, 2013
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A method to remove epitaxial semiconductor layers from a substrate by growing an epitaxial sacrificial layer on the substrate where the sacrificial layer is a transition metal nitride (TMN) or a TMN ternary compound, growing one or more epitaxial device layers on the sacrificial layer, and separating the device layers from the substrate by etching the sacrificial layer to completely remove the sacrificial layer without damaging or consuming the substrate or any device layer. Also disclosed are the related semiconductor materials made by this method.

First claim

What is claimed as new and desired to be protected by Letters Patent of the United States is:

1. A method to remove epitaxial device layers from a substrate, comprising: growing an epitaxial sacrificial layer on the substrate, wherein the epitaxial sacrificial layer comprises a transition metal nitride (TMN) selected from the group consisting of Ta 2 N, Nb 2 N, TaN x , NbN x , WN x , and MoN x , where x>0, or a TMN ternary compound comprising a transition metal selected from the group consisting of Ta, Nb, W, and Mo; growing one or more epitaxial device layers directly on the epitaxial sacrificial layer, wherein the epitaxial sacrificial layer is grown immediately prior to the growing of the one or more epitaxial device layers; and separating the epitaxial device layers from the substrate by etching the epitaxial sacrificial layer to completely remove the epitaxial sacrificial layer without damaging or consuming the substrate or any epitaxial device layer.

2. The method of claim 1 , wherein the substrate comprises SiC.

3. The method of claim 2 , wherein the substrate has a hexagonal crystal structure, consisting of the 4H or 6H polytype.

4. The method of claim 1 , wherein the substrate comprises AlN, GaN, Si (111), or sapphire.

5. The method of claim 4 , wherein the crystal structure of the substrate has 3-fold symmetry.

6. The method of claim 1 , wherein the etching is performed using XeF 2 gas.

7. The method of claim 1 , wherein the etching is performed using a wet-chemical etchant.

8. The method of claim 7 , wherein the wet-chemical etchant comprises hydrofluoric acid, nitric acid, or hydrochloric acid.

9. The method of claim 1 , wherein the etching is continuous.

10. The method of claim 1 , wherein the etching is pulsed.

11. The method of claim 1 , wherein the one or more epitaxial layers comprise a Group III nitride or SiC.

12. The method of claim 1 , additionally comprising bonding a carrier substrate to the epitaxial layers using a bonding layer.

13. A device made by the method comprising: growing an epitaxial sacrificial layer on a substrate, wherein the epitaxial sacrificial layer comprises a transition metal nitride (TMN) selected from the group consisting of Ta 2 N, Nb 2 N, TaN x , NbN x , WN x , and MoN x , where x>0, or a TMN ternary compound comprising a transition metal selected from the group consisting of Ta, Nb, W, and Mo; growing one or more epitaxial device layers directly on the epitaxial sacrificial layer, wherein the epitaxial sacrificial layer is either grown immediately prior to the growing of the one or more epitaxial device layers or cleaned prior to the growing of the one or more epitaxial device layers; and separating the epitaxial device layers from the substrate by etching the epitaxial sacrificial layer to completely remove the epitaxial sacrificial layer without damaging or consuming the substrate or any epitaxial device layer.

14. The device of claim 13 , wherein the substrate comprises SiC.

15. The device of claim 14 , substrate has a hexagonal crystal structure, consisting of the 4H or 6H polytype.

16. The device of claim 13 , wherein the substrate comprises AlN, GaN, Si (111), or sapphire.

17. The device of claim 16 , wherein the crystal structure of the substrate has 3-fold symmetry.

18. The device of claim 13 , wherein the etching is performed using XeF 2 gas.

19. The device of claim 13 , wherein the etching is performed using a wet-chemical etchant.

20. The device of claim 19 , wherein the wet-chemical etchant comprises hydrofluoric acid, nitric acid, or hydrochloric acid.

21. The device of claim 13 , wherein the etching is continuous.

22. The device of claim 13 , wherein the etching is pulsed.

23. The device of claim 13 , wherein the one or more epitaxial device layers comprise a Group III nitride or SiC.

24. The device of claim 13 , additionally comprising bonding a carrier substrate to the epitaxial device layers using a bonding layer.

25. A method to remove epitaxial device layers from a substrate, comprising: growing an epitaxial sacrificial layer on the substrate, wherein the epitaxial sacrificial layer comprises a transition metal nitride (TMN) selected from the group consisting of Ta 2 N, Nb 2 N, TaN x , NbN x , WN x , and MoN x , where x>0, or a TMN ternary compound comprising a transition metal selected from the group consisting of Ta, Nb, W, and Mo; growing one or more epitaxial device layers directly on the epitaxial sacrificial layer, wherein if the epitaxial sacrificial layer is not grown immediately prior to the growing of the one or more epitaxial device layers, the epitaxial sacrificial layer is cleaned prior to the growing of the one or more epitaxial device layers; and separating the epitaxial device layers from the substrate by etching the epitaxial sacrificial layer to completely remove the epitaxial sacrificial layer without damaging or consuming the substrate or any epitaxial device layer.

26. The method of claim 25 , wherein the substrate comprises SiC.

27. The method of claim 26 , wherein the substrate has a hexagonal crystal structure, consisting of the 4H or 6H polytype.

28. The method of claim 25 , wherein the substrate comprises AlN, GaN, Si (111), or sapphire.

29. The method of claim 28 , wherein the crystal structure of the substrate has 3-fold symmetry.

30. The method of claim 25 , wherein the etching is performed using XeF 2 gas.

31. The method of claim 25 , wherein the etching is performed using a wet-chemical etchant.

32. The method of claim 31 , wherein the wet-chemical etchant comprises hydrofluoric acid, nitric acid, or hydrochloric acid.

33. The method of claim 25 , wherein the etching is continuous.

34. The method of claim 25 , wherein the one or more epitaxial device layers comprise a Group III nitride or SiC.

35. The method of claim 25 , additionally comprising bonding a carrier substrate to the epitaxial device layers using a bonding layer.

36. The method of claim 1 , further comprising the step of reusing the substrate for subsequent epitaxial device layer growth.

37. The device of claim 13 , wherein the substrate is reused for subsequent epitaxial device layer growth.

38. The method of claim 25 , further comprising the step of reusing the substrate for subsequent epitaxial device layer growth.

Assignees

• Meyer David J
• Downey Brian P
• Us Navy

Inventors

• Meyer David J
• Downey Brian P

Classifications

• H10P72/7434

  used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate · CPC title

• H10W10/181

  Semiconductor-on-insulator [SOI] isolation regions, e.g. buried oxide regions of SOI wafers · CPC title

• H10P95/112

  leaving a reusable substrate, e.g. epitaxial lift off · CPC title

• H10P95/11

  Separation of active layers from substrates · CPC title

• H10P90/1922

  using silicon etch back techniques, e.g. BESOI or ELTRAN · CPC title