Granted Patent B1

US 9,287,494 · App. 13/954,766 · Granted Mar 15, 2016

Abstract

Claims (30)

1. A method for fabricating a magnetic tunnel junction (MTJ) comprising:

forming a stack that includes a tunnel barrier layer;

annealing the stack immediately after the tunnel barrier layer is deposited;

cooling the stack under vacuum; and

then depositing at least one overlayer on the tunnel barrier layer to form the MTJ after the step of cooling the stack under vacuum.

2. The method of claim 1 , further comprising depositing a free layer on the tunnel barrier followed by a capping layer on the free layer.

3. The method of claim 1 , wherein the tunnel barrier layer has an approximate thickness of between four and seven angstroms.

4. The method of claim 1 , wherein the stack is annealed at a temperature between 155° C. and 200° C.

5. The method of claim 1 , wherein annealing occurs in the absence of a magnetic field in a pre-heated chamber.

6. The method of claim 1 , wherein the stack is cooled for approximately 5-35 minutes in a holding chamber that is maintained at room temperature.

7. The method of claim 1 , wherein the MTJ has an MR ratio that increases as the cooling period increases.

8. The product formed by the process of claim 1 .

9. A method for fabricating a magnetic tunnel junction (MTJ) comprising:

providing a stack of layers;

depositing a tunnel barrier layer on the stack of layers to form an intermediate structure;

annealing the intermediate structure after the tunnel barrier layer is deposited and in the absence of a magnetic field; and

cooling the tunnel barrier layer under vacuum prior to depositing at least one overlayer to form the MTJ.

10. The method of claim 9 , further comprising providing a free layer on the tunnel barrier layer, and a capping layer on the free layer.

11. The method of claim 9 , wherein the tunnel barrier layer has an approximate thickness of between four and seven angstroms.

12. The method of claim 9 , wherein the intermediate structure is annealed at a temperature between 155° C. to 200° C. prior to deposition of the at least one overlayer.

13. The method of claim 9 , wherein annealing occurs in a pre-heated chamber.

14. The method of claim 9 , wherein the intermediate structure is placed in a holding chamber for a period of 5-35 minutes to cool to a temperature between 24° C.-190° C.

15. The method of claim 14 , wherein the holding chamber is maintained at a temperature of between 24° C.-30° C.

16. The method of claim 9 , wherein the MTJ has an MR ratio that increases as the cooling period increases.

17. The method of claim 9 , wherein the MTJ has an MR ratio between 60% and 90% at resistance-area product values between 0.55 and 0.85 Ωμm 2 .

18. A method for fabricating a magnetic tunnel junction (MTJ) comprising:

forming a stack of layers;

depositing a tunnel barrier layer on the stack of layers to form an intermediate structure

annealing the intermediate structure after the tunnel barrier layer is deposited; and

cooling the tunnel barrier layer under vacuum prior to depositing at least one overlayer to form an MTJ, wherein the MTJ has an MR ration between 60% and 90% at resistance-area product values between 0.55 and 085 Ωμm 2 .

Assignments (9)