WAFER SCALE EPITAXIAL GRAPHENE TRANSFER

• US 20140291282A1
• Filed: 04/02/2013
• Published: 10/02/2014
• Est. Priority Date: 04/02/2013
• Status: Active Grant

• Current Assignee: Elpis Technologies Inc. (Wi-LAN Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Bedell, Stephen W., Dimitrakopoulos, Christos D., Fogel, Keith E., Hannon, James B., Kim, Jeehwan, Park, Hongsik, Pfeiffer, Dirk, Sadana, Devendra K.
• Granted Patent: US 9,096,050 B2
• Time in Patent Office: Days
• US Class Current: 216/2
• CPC Class Codes: C01B 32/184 Preparation
• CPC Class Codes: H01L 21/02002 Preparing wafers
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02527 Carbon, e.g. diamond-like carbon
• CPC Class Codes: H01L 21/0272 for lift-off processes
• 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 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 2221/68345 used as a support during the manufacture of self supporting substrates
• CPC Class Codes: H01L 2221/68368 used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate
• CPC Class Codes: H01L 2221/68381 Details of chemical or physical process used for separating the auxiliary support from a device or wafer
• CPC Class Codes: H01L 29/1606 Graphene
• CPC Class Codes: Y10T 156/11 Methods of delaminating, per se; i.e. , separating at bonding face
• CPC Class Codes: Y10T 156/1153 Temperature change for delamination [e.g., heating during delaminating, etc.]

Abstract

A method for transfer of a two-dimensional material includes forming a spreading layer of a two-dimensional material on a substrate, the spreading layer having a monolayer. A stressor layer is formed on the spreading layer, and the stressor layer is configured to apply stress to a closest monolayer of the spreading layer. The closest monolayer is exfoliated by mechanically splitting the spreading layer wherein the closest monolayer remains on the stressor layer.

Claims

1. A method for transfer of a two-dimensional material, comprising:

forming a spreading layer of a two-dimensional material on a substrate, the spreading layer having at least one monolayer;

forming a stressor layer on the spreading layer, the stressor layer being configured to apply stress to at least a closest monolayer of the spreading layer; and

exfoliating at least the closest monolayer by mechanically splitting the spreading layer wherein at least the closest monolayer remains on the stressor layer.

2. The method as recited in claim 1, wherein the substrate includes SiC and the spreading layer includes graphene, and wherein forming the spreading layer includes heating the SiC substrate to a temperature greater than 1000 degrees C.

3. The method as recited in claim 1, wherein forming the stressor layer includes depositing one of a metal, an oxide and a semiconductor to induce stress in the at least closest monolayer of the spreading layer.

4. The method as recited in claim 1, wherein exfoliating the at least closest monolayer includes lifting off the at least closest monolayer by using induced stress of the stressor layer to overcome Van der Waals forces holding the closet monolayers to adjacent material.

5. The method as recited in claim 1, further comprising:

bonding a handle substrate to the stressor layer to affect the step of exfoliating.

6. The method as recited in claim 1, further comprising:

transferring at least the closest monolayer to a second substrate.

7. The method as recited in claim 1, wherein the at least the closest monolayer is exfoliated on a wafer scale.

8. The method as recited in claim 1, further comprising adjusting stress in the stressor layer during or after its formation.

9. The method as recited in claim 8, wherein adjusting stress in the stressor layer includes one of heating, cooling, thickening or densifying the stressor layer prior to splitting the spreading layer.

10. A method for transfer of graphene, comprising:

forming a spreading layer of graphene on a silicon carbide (SiC) substrate, the spreading layer having at least one monolayer;

depositing a stressor layer on the spreading layer, the stressor layer being configured to apply stress to at least a closest monolayer of the spreading layer;

bonding a handle substrate to the stressor layer;

splitting the spreading layer by exfoliating at least the closest monolayer from the spreading layer wherein the at least closest monolayer remains on the stressor layer; and

transferring the at least closest monolayer on the stressor layer using the handle substrate.

11. The method as recited in claim 10, wherein forming the spreading layer includes heating the SiC substrate to a temperature greater than 1000 degrees C.

12. The method as recited in claim 10, wherein forming the stressor layer includes depositing one of a metal, an oxide and a semiconductor to induce stress in the at least closest monolayer of the spreading layer.

13. The method as recited in claim 10, wherein splitting includes lifting off the at least closest monolayer by using induced stress of the stressor layer to overcome Van der Waals forces holding the at least closet monolayer to adjacent material.

14. The method as recited in claim 10, wherein transferring the at least closest monolayer includes transferring the at least closest monolayer to a second substrate.

15. The method as recited in claim 10, wherein the at least closest monolayer is exfoliated on a wafer scale.

16. The method as recited in claim 10, further comprising adjusting stress in the stressor layer during or after its formation.

17. The method as recited in claim 16, wherein adjusting stress in the stressor layer includes one of heating, cooling, thickening or densifying the stressor layer prior to splitting the spreading layer.

20. The method as recited in claim 10, wherein at least the closest monolayer is exfoliated on a wafer scale.

18. A method for transfer of graphene, comprising:

forming a spreading layer including a monolayer of graphene on a silicon carbide substrate by heating the substrate to a temperature greater than 1000 degrees C., wherein a buffer layer of SiC in contact with the substrate includes covalent bonds to underlying material;

depositing a stressor layer on the spreading layer, the stressor layer being configured to apply stress to at least a closest monolayer of the spreading layer;

bonding a handle substrate to the stressor layer;

splitting the spreading layer by exfoliating at least the closest monolayer from the spreading layer wherein at least the closest monolayer remains on the stressor layer by using induced stress of the stressor layer to overcome Van der Waals forces holding at least the closet monolayer to adjacent materials;

transferring at least the closest monolayer on the stressor layer using the handle substrate; and

etching away the stressor layer to release at least the closest monolayer onto a second substrate for device formation.

19. The method as recited in claim 18, wherein forming the stressor layer includes depositing one of a metal, an oxide and a semiconductor to induce stress in the closest monolayer of the spreading layer.