Methods for transferring a useful layer of silicon carbide to a receiving substrate

• US 20050266659A1
• Filed: 08/04/2005
• Published: 12/01/2005
• Est. Priority Date: 01/23/2002
• Status: Active Grant

• Current Assignee: Soitec Silicon On Insulator Technologies SA (Soitec S.A.)
• Original Assignee: Soitec Silicon On Insulator Technologies SA (Soitec S.A.)
• Inventors: Ghyselen, Bruno, Letertre, Fabrice
• Granted Patent: US 7,262,113 B2
• Time in Patent Office: Days
• US Class Current: 438/459
• CPC Class Codes: H01L 21/02032 by reclaiming or re-processing
• CPC Class Codes: H01L 21/187 by direct bonding
• 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 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 21/266 using masks H01L21/26586 takes precedence
• CPC Class Codes: H01L 21/7602 between components manufactured in an active substrate comprising SiC compounds
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond

Abstract

Methods for transferring a useful layer of silicon carbide to a receiving substrate are described. In an embodiment, the invention relates to a method for recycling of a silicon carbide source substrate by removal of the excess zone followed by a finishing step to prepare the source substrate for recycling and reuse. Preferably, the excess zone is removed by a thermal budget where the temperature and time of such treatment causes exfoliation of the excess zone. The finishing step is performed in a manner to provide the desired surface roughness for the substrate so that it can be recycled for re-use. The technique includes implanting at least H⁺ ions through a front face of a source substrate of silicon carbide with an implantation energy E greater than or equal to 95 keV and an implantation dose D chosen to form an optimal weakened zone near a mean implantation depth, the optimal weakened zone defining the useful layer and a remainder portion of the source substrate. The method also includes bonding the front face of the source substrate to a contact face of the receiving substrate, and detaching the useful layer from the remainder portion of the source substrate along the weakened zone while minimizing or avoiding forming an excess zone of silicon carbide material at the periphery of the useful layer that was not transferred to the receiving substrate during detachment.

Claims

1. A method for recycling a SiC source substrate, which comprises:

implanting at least H⁺ ions through a front face of a source substrate of silicon carbide with an implantation energy E greater than or equal to 95 keV and an implantation dose D of H⁺ ions sufficient to form an optimal weakened zone near a mean implantation depth, with the optimal weakened zone defining the useful layer and a remainder portion of the source substrate;

bonding the front face of the source substrate to a contact face of the receiving substrate;

detaching the useful layer from the remainder portion of the source substrate along the weakened zone while minimizing or avoiding forming an excess zone of silicon carbide material at the periphery of the useful layer that was not transferred to the receiving substrate during detachment, to thus facilitate recycling the remainder portion of the source substrate;

applying a thermal budget that is appropriate to remove the excess zone, and

eliminating substrate surface roughness via a finishing step to prepare the source substrate for recycling and reuse.

2. The method of claim 1 wherein the implantation dose D of H⁺ ions, expressed as a number of H⁺ ions/cm², satisfies the equation:

[(E×

1×

10¹⁴+5×

10¹⁶)/1.1]≦

D≦

[(E×

1×

10¹⁴+5×

10¹⁶)/(0.9)].

3. The method of claim 1, wherein the implanted ions comprise H⁺ ions, a combination of H⁺ ions and helium ions or a combination of H⁺ ions and boron ions.

4. The method of claim 1, which further comprises implanting H⁺ ions while maintaining the source substrate at a temperature that is no greater than 200°

C.

5. The method of claim 1, wherein the source substrate comprises a disoriented monocrystalline silicon carbide.

6. The method of claim 1, which further comprises detaching the useful layer along the optimal weakened zone by applying a thermal budget or mechanical stresses in a manner so that no excess zone remains.

7. The method of claim 6, wherein the useful layer is detached by applying a thermal budget at a temperature that is greater than about 700°

C.

8. The method of claim 1, which further comprises implanting ions in a random fashion.

9. The method of claim 1, which further comprises providing a layer of amorphous material on the source substrate before implanting ions, wherein the thickness of the amorphous material is less than or equal to about 50 nanometers.

10. The method of claim 9, wherein the amorphous material is formed of silicon oxide or silicon nitride.

11. The method of claim 1, wherein the bonding step comprises molecularly adhering the receiving substrate to the front face of the source substrate.

12. The method of claim 11, which further comprises providing an intermediate bonding layer on at least one of the front face and the contact face.

13. The method of claim 12, wherein the intermediate bonding layer comprises an amorphous material.

14. The method of claim 13, wherein the amorphous material is silicon oxide or silicon nitride.

15. The method of claim 1, wherein the receiving substrate comprises at least one of silicon, silicon carbide, gallium nitride, aluminum nitride, sapphire, indium phosphide, gallium arsenide, or germanium.

16. The method of claim 1, wherein the receiving substrate comprises silicon having a low oxygen content.

17. The method of claim 1, further comprising providing a finished front face of the remainder of the source substrate after detachment for use in subsequent bonding operations.

18. The method of claim 1 wherein the layer is detached by heating the source substrate/receiving substrate assembly to a temperature of above 700°

C. until the layer detaches.

19. The method of claim 1 wherein the layer is detached by heating the source substrate/receiving substrate assembly to a temperature of above 800°

C. until the layer detaches.

20. The method of claim 1 wherein the layer is detached while minimizing formation of an excess zone of silicon carbide material at the periphery of the useful layer that was not transferred to the receiving substrate during detachment.

21. The method of claim 1 wherein the layer is detached while completely avoiding formation of an excess zone of silicon carbide material at the periphery of the useful layer that was not transferred to the receiving substrate during detachment.

22. The method of claim 1 wherein the excess zone is removed by exfoliation.

23. The method of claim 1 wherein the useful layer is provided by a monocrystalline silicon carbide SiC₄H material.