Magnetic random access memory and manufacturing method thereof

1. A method of manufacturing a magnetic random access memory (MRAM) cell, the method comprising:

forming a first magnetic layer over a substrate;

forming a first non-magnetic material layer over the first magnetic layer;

forming a second magnetic layer over the first non-magnetic material layer;

forming a second non-magnetic material layer over the second magnetic layer;

forming a third non-magnetic material layer in direct contact with the second non-magnetic material layer; and

patterning the third non-magnetic material layer, the second non-magnetic material layer, the second magnetic layer, the first non-magnetic material layer and the first magnetic layer, thereby forming the MRAM cell,

wherein the second magnetic layer in the MRAM cell includes a plurality of magnetic material pieces separated from each other, and

each of the second and third non-magnetic material layers is made of a dielectric material.

2. The method of claim 1 , wherein the plurality of magnetic material pieces are separated from each other by the dielectric material of the second non-magnetic material layer.

3. The method of claim 2 , wherein the second non-magnetic material layer is made of MgO.

4. The method of claim 2 , wherein the dielectric material of the second non-magnetic material layer is same as the dielectric material of the third non-magnetic material layer.

5. The method of claim 2 , wherein the dielectric material of the second non-magnetic material layer is different from the dielectric material of the third non-magnetic material layer.

6. The method of claim 1 , wherein the second non-magnetic material layer is formed in direct contact with the first non-magnetic material layer.

7. The method of claim 1 , wherein sizes of the plurality of magnetic material pieces in plan view are random.

8. The method of claim 1 , wherein heights of the plurality of magnetic material pieces are random.

9. The method of claim 1 , wherein a thickness of the second magnetic layer is in a range from 0.2 nm to 1.5 nm.

10. The method of claim 1 , wherein a size of each of the plurality of magnetic material pieces in plan view is in a range from 1 nm to 10 nm.

11. The method of claim 1 , wherein spaces between adjacent pieces of magnetic material in plan view are in a range from 0.2 nm to 5 nm.

12. The method of claim 1 , wherein each of the plurality of magnetic material pieces has one magnetic domain.

13. A method of manufacturing a magnetic random access memory (MRAM) cell, the method comprising:

forming a first magnetic layer over a substrate;

forming a first non-magnetic material layer over the first magnetic layer;

forming a second magnetic layer over the first non-magnetic material layer;

forming a second non-magnetic material layer over the second magnetic layer and in direct contact with the first non-magnetic material layer; and

patterning the second non-magnetic material layer, the second magnetic layer, the first non-magnetic material layer and the first magnetic layer, thereby forming the MRAM cell,

wherein the second magnetic layer in the MRAM cell includes a plurality of islands of magnetic material separated from each other, and

a thickness of the second non-magnetic material layer is greater than a largest height of the plurality of islands of magnetic material.

14. The method of claim 13 , wherein the plurality of islands of magnetic material are separated from each other by the second non-magnetic material layer.

15. The method of claim 13 , wherein the second non-magnetic material layer is made of MgO.

16. The method of claim 13 , wherein each of the plurality of islands of magnetic material has one magnetic domain.

17. A semiconductor device including a magnetic random access memory (MRAM) cell, wherein the MRAM cell comprises:

a first magnetic layer disposed over a substrate;

a first non-magnetic material layer made of a non-magnetic material and disposed over the first magnetic layer;

a second magnetic layer disposed directly on the first non-magnetic material layer; and

a second non-magnetic material layer disposed over the second magnetic layer;

wherein the second magnetic layer includes a plurality of magnetic material pieces separated from each other, and

a thickness of the second non-magnetic material layer is greater than a thickness of the second magnetic layer.

18. The semiconductor device of claim 17 , wherein the plurality of magnetic material pieces are separated from each other by a non-magnetic material.