Bonded intermediate substrate and method of making same

• US 20060255341A1
• Filed: 04/21/2006
• Published: 11/16/2006
• Est. Priority Date: 04/21/2005
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Aonex Technologies Inc. (AmberWave Systems Corporation)
• Inventors: Park, Young-Bae, Pinnington, Thomas Henry, Ladous, Corinne, Olson, Sean, Zahler, James M., Atwater, Harry A. Jr., Tsai, Charles
• Granted Patent: US 8,101,498 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/405 Reflective materials

Abstract

An intermediate substrate includes a handle substrate bonded to a thin layer suitable for epitaxial growth of a compound semiconductor layer, such as a III-nitride semiconductor layer. The handle substrate may be a metal or metal alloy substrate, such as a molybdenum or molybdenum alloy substrate, while the thin layer may be a sapphire layer. A method of making the intermediate substrate includes forming a weak interface in the source substrate, bonding the source substrate to the handle substrate, and exfoliating the thin layer from the source substrate such that the thin layer remains bonded to the handle substrate.

Claims

1. An intermediate substrate comprising a thin layer suitable for epitaxial growth of a compound semiconductor material bonded to a handle substrate;

wherein;

(a) the handle substrate comprises a metal or a metal alloy substrate;

or (b) the thin layer comprises a thin sapphire layer.

2. The intermediate substrate of claim 1, wherein the coefficient of thermal expansion of the handle substrate is closely matched to a coefficient of thermal expansion of the compound semiconductor material.

3. The intermediate substrate of claim 1, wherein the handle substrate comprises the metal or the metal alloy.

4. The intermediate substrate of claim 3, wherein the handle substrate comprises Mo or a Mo alloy.

5. The intermediate substrate of claim 4, wherein the handle substrate comprises MoW, TZM or lanthanum oxide doped Mo.

6. The intermediate substrate of claim 1, wherein the thin layer comprises the sapphire layer.

7. The intermediate substrate of claim 6, wherein the sapphire layer is partially masked to allow for selective area growth or lateral overgrowth of III-nitride materials.

8. The intermediate substrate of claim 1, wherein the thin layer comprises a semiconductor layer.

9. The intermediate substrate of claim 8, wherein the thin layer comprises GaN or AlN.

10. The intermediate substrate of claim 1, further comprising at least one of:

(a) a bonding layer located between the handle substrate and the thin layer;

(b) an adhesion layer located between the handle substrate and the bonding layer;

(c) a reflective layer located between the handle substrate and the thin layer;

(d) a diffusion barrier located between the handle substrate and the thin layer, wherein the diffusion barrier reduces out-diffusion of contaminants from the handle substrate into the thin layer;

or

(e) an encapsulating layer which encapsulates the handle substrate to prevent decomposition of the handle substrate during epitaxial growth of the compound semiconductor layer.

11. The intermediate substrate of claim 1, wherein the thin layer is transferred from a source substrate and bonded to the handle substrate.

12. The intermediate substrate of claim 1, wherein:

the handle substrate comprises the metal or the metal alloy substrate;

the thin layer comprises the thin sapphire layer; and

the handle substrate is thicker than the thin layer.

13. The intermediate substrate of claim 1, further comprising the compound semiconductor layer epitaxially grown on the thin layer of the intermediate substrate.

14. The intermediate substrate of claim 13, wherein:

the compound semiconductor layer comprises GaN; and

the handle substrate is removable via chemical or mechanical removal methods without damaging the compound semiconductor layer.

15. A light-emitting device, comprising:

a metal or metal alloy final substrate;

a conductive bonding layer on the substrate;

a reflective p-type contact located over the bonding layer;

a plurality of single crystal III-nitride semiconductor layers including at least one light-emitting layer located over the p-type contact layer;

a single crystal sapphire layer located over the plurality of single crystal III-nitride semiconductor layers patterned with openings to enable electrical contact; and

a light transmitting n-type contact located over the sapphire layer.

16. A method of making an intermediate substrate, comprising:

forming a weak interface in a source substrate;

bonding the source substrate to a handle substrate; and

exfoliating a thin layer from the source substrate such that the thin layer remains bonded to the handle substrate;

wherein;

(a) the handle substrate comprises a metal or a metal alloy substrate;

or

(b) the thin layer comprises a thin sapphire layer.

17. The method of claim 16, wherein:

the handle substrate comprises a metal or a metal alloy substrate; and

the thin layer comprises a single crystal sapphire layer.

18. The method of claim 16, wherein the handle substrate comprises a metal or a metal alloy substrate.

19. The method of claim 18, wherein the handle substrate comprises a Mo or Mo alloy substrate.

20. The method of claim 19, wherein the thin layer comprises a single crystal GaN, Si(111) or SiC layer.

21. The method of claim 16, wherein the handle substrate comprises polycrystalline aluminum nitride or polycrystalline silicon carbide.

22. The method of claim 16, wherein:

the thin layer is suitable for epitaxial growth of a III-nitride semiconductor layer; and

a linear thermal expansion coefficient of the handle substrate is 5.2×

10<sup>−

6</sup>/K to 6.3×

10<sup>−

6</sup>/K averaged between room temperature and 1000 degrees C.

23. The method of claim 16, wherein:

the step of forming a weak interface comprises implanting ions into the source substrate; and

the step of exfoliating comprises annealing the bonded source and handle substrates at a temperature sufficient to exfoliate the thin layer from the source substrate along the weak interface.

24. The method of claim 23, wherein:

the source substrate comprises a substrate of a first material which is the same as a material of the thin layer, or the source substrate comprises a single crystal layer of a first material which is the same as the material of the thin layer located over a substrate of a second material which is different from the first material; and

the step of forming a weak interface comprises implanting helium into the source substrate to form defect structures in the source substrate, followed by implanting hydrogen into the source substrate to at least one of bind to, stabilize or passivate internal surfaces of the defect structures.

25. The method of claim 16, further comprising epitaxially growing a single crystal compound semiconductor layer on the thin layer.

26. The method of claim 25, wherein:

the compound semiconductor layer comprises a single crystal III-nitride layer; and

a coefficient of thermal expansion of the handle substrate is closely matched to a coefficient of thermal expansion of the III-nitride layer.

27. The method of claim 26, further comprising:

epitaxially growing layers of a semiconductor light-emitting device or a transistor over the III-nitride layer;

forming a conductive device substrate is contact with the light-emitting device or the transistor; and

removing the handle substrate.

28. The method of claim 27, further comprising removing at least a portion of the thin layer.

29. A method of making a substrate, comprising:

transferring a thin single crystal layer of a first material which is suitable for epitaxial growth of a single crystal III-nitride semiconductor layer onto a handle substrate having a CTE which is closely CTE matched to a CTE of the 111-nitride semiconductor layer;

epitaxially growing a thick single crystal 111-nitride semiconductor layer on the thin single crystal layer of the first material; and

removing the handle substrate.

30. The method of claim 29, further comprising removing the thin single crystal layer of the first material such that the thick single crystal 111-nitride semiconductor layer forms a free-standing single crystal 111-nitride substrate having a thickness of greater than 100 microns.

31. A method of making a bonded intermediate substrate, comprising:

forming a weak interface in a GaN source substrate by implanting ions into an N-terminated surface of the GaN source substrate;

bonding the N-terminated surface of the GaN source substrate to a handle substrate; and

exfoliating a thin GaN single crystal layer from the source substrate such that the thin GaN exfoliated single crystal layer remains bonded to the handle substrate and a Ga-terminated surface of the thin GaN single crystal layer is exposed.

32. The method of claim 31, wherein the handle substrate comprises a metal or a metal alloy substrate having a linear thermal expansion coefficient of 5.2×

10<sup>−

6</sup>/K to 6.3×

10<sup>−

6</sup>/K averaged between room temperature and 1000 degrees C.