Carrier-assisted method for parting crystalline material along laser damage region

Patent metadata

Field	Value
Publication number	US-11901181-B2
Application number	US-202117225384-A
Country	US
Kind code	B2
Filing date	Apr 8, 2021
Priority date	Dec 29, 2018
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A method for removing a portion of a crystalline material (e.g., SiC) substrate includes joining a surface of the substrate to a rigid carrier (e.g., >800 μm thick), with a subsurface laser damage region provided within the substrate at a depth relative to the surface. Adhesive material having a glass transition temperature above 25° C. may bond the substrate to the carrier. The crystalline material is fractured along the subsurface laser damage region to produce a bonded assembly including the carrier and a portion of the crystalline material. Fracturing of the crystalline material may be promoted by (i) application of a mechanical force proximate to at least one carrier edge to impart a bending moment in the carrier; (ii) cooling the carrier when the carrier has a greater coefficient of thermal expansion than the crystalline material; and/or (iii) applying ultrasonic energy to the crystalline material.

First claim

What is claimed is:

1. A crystalline material processing method comprising:
temporarily bonding a rigid carrier to a first surface of a crystalline material comprising a semiconductor with an intervening adhesive material, wherein the crystalline material comprises a substrate having a subsurface laser damage region at a depth relative to the first surface, the rigid carrier has a modulus of elasticity of at least 20 GPa, and at least one of a maximum length or maximum width of at least a portion of the rigid carrier exceeds a corresponding maximum length or maximum width of the substrate; and
fracturing the crystalline material along or proximate to the subsurface laser damage region to yield a bonded assembly comprising the rigid carrier, the adhesive material, and a portion of the crystalline material removed from the substrate, wherein the portion of the crystalline material removed from the substrate comprises a thickness of at least 160 microns.

2. The crystalline material processing method of claim 1 , wherein the adhesive material comprises a thermoplastic material.

3. The crystalline material processing method of claim 1 , wherein the adhesive material has a glass transition temperature T g of greater than 25° C.

4. The crystalline material processing method of claim 1 , wherein the adhesive material has a Shore D durometer value of at least 70 when the adhesive material is at 25° C.

5. The crystalline material processing method of claim 1 , wherein the adhesive material has a modulus of elasticity of at least 7 MPa when the adhesive material is at 25° C.

6. The crystalline material processing method of claim 1 , wherein the adhesive material has a thickness of less than 50 microns.

7. The crystalline material processing method of claim 1 , wherein the rigid carrier has a thickness of greater than 800 microns.

8. The crystalline material processing method of claim 1 , wherein:
the rigid carrier comprises a first face and a second face that opposes the first face;
the adhesive material is arranged in contact with the first face; and
the second face is devoid of any adhesive material and devoid of any stress-producing material.

9. The crystalline material processing method of claim 1 , wherein the rigid carrier comprises a crystalline material.

10. The crystalline material processing method of claim 1 , further comprising performing at least one additional processing step on the portion of the crystalline material while the portion of the crystalline material remains part of the bonded assembly.

11. The crystalline material processing method of claim 1 , further comprising bonding an additional rigid carrier to a second surface of the crystalline material that opposes the first surface, prior to said fracturing, the additional rigid carrier having a modulus of elasticity of at least 20 GPa.

12. The crystalline material processing method of claim 11 , wherein at least one of a maximum length or maximum width of at least a portion of the additional rigid carrier exceeds a corresponding maximum length or maximum width of the substrate.

13. The crystalline material processing method of claim 12 , wherein the fracturing comprises applying a mechanical force proximate to at least one edge of the rigid carrier, and the mechanical force is configured to impart a bending moment in at least a portion of the rigid carrier, and the mechanical force is further configured to pry apart the rigid carrier and the additional rigid carrier.

14. The crystalline material processing method of claim 1 , wherein the crystalline material comprises polycrystalline material.

15. The crystalline material processing method of claim 1 , wherein the crystalline material comprises SiC.

16. The crystalline material processing method of claim 1 , further comprising roughening, texturing, and/or etching at least one of (i) the first surface of the crystalline material or (ii) an adjacent surface of the rigid carrier prior to the temporarily bonding of the rigid carrier to the first surface of a crystalline material with the adhesive material.

17. The crystalline material processing method of claim 1 , wherein the portion of the crystalline material removed from the substrate comprises a free-standing wafer configured for growth of at least one epitaxial layer thereon.

18. The crystalline material processing method of claim 1 , wherein the portion of the crystalline material removed from the substrate comprises a device wafer including at least one epitaxial layer grown thereon.

19. The crystalline material processing method of claim 1 , wherein the fracturing comprises applying a mechanical force proximate to at least one edge of the rigid carrier, and the mechanical force is configured to impart a bending moment in at least a portion of the rigid carrier.

20. A crystalline material processing method comprising:
bonding a first rigid carrier to a first surface of a crystalline material comprising a semiconductor, wherein the crystalline material comprises a substrate having a subsurface laser damage region at a depth relative to a first surface of the substrate, the first rigid carrier having a modulus of elasticity of at least 20 GPa;
bonding a second rigid carrier to a second surface of the crystalline material, the second rigid carrier having a modulus of elasticity of at least 20 GPa; and
following the bonding steps, fracturing the crystalline material along or proximate to the subsurface laser damage region to yield a bonded assembly comprising the first rigid carrier and a portion of the crystalline material removed from the substrate, wherein the portion of the crystalline material removed from the substrate comprises a thickness of at least 160 microns.

21. The crystalline material processing method of claim 20 , wherein:
at least one of a maximum length or maximum width of at least a portion of the first rigid carrier exceeds a corresponding maximum length or maximum width of the substrate; and
at least one of a maximum length or maximum width of at least a portion of the second rigid carrier exceeds a corresponding maximum length or maximum width of the substrate.

22. The crystalline material processing method of claim 21 , wherein the fracturing comprises applying a mechanical force proximate to one or more edges of the first rigid carrier and the second rigid carrier, and the mechanical force is configured to impart a bending moment in at least one of the first rigid carrier or the second rigid carrier.

23. The crystalline material processing method of claim 20 , wherein at least one of the bonding of the first rigid carrier to the first surface of the crystalline material or the bonding of the second rigid carrier to the second surface of the crystalline material comprises anodic bonding.

24. The crystalline material processing method of claim 20 , wherein at least one of the bonding of the first rigid carrier to the first surface of the crystalline material or the bonding of the second rigid carrier to the second surface of the crystalline material comprises adhesive bonding utilizing an adhesive material.

25. The crystalline material processing method of claim 24 , wherein:
the first rigid carrier comprises a first face and a second face that opposes the first face;
the adhesive material is arranged in contact with the first face; and
the second face is devoid of any adhesive material and devoid of any stress-producing mater

Assignees

• Wolfspeed Inc

Inventors

• Donofrio Matthew
• Edmond John
• Kong Hua-Shuang
• Balkas Elif

Classifications

• H10P90/1914

  using bonding · CPC title

• H10P14/2921

  being crystalline insulating materials · CPC title

• H10P54/52

  by cleaving · CPC title

• H10P10/128 Primary

  by direct semiconductor to semiconductor bonding · CPC title

• H10W46/401

  for identification or tracking · CPC title