MRAM device and fabrication method thereof

1. A magnetoresistive random access memory (MRAM) device comprising:

a bottom electrode over a substrate;

a stack over the bottom electrode, the stack comprising a magnetic tunnel junction (MTJ) and a top electrode, the MTJ having a first width;

a dielectric material along a curved sidewall of the stack, a portion of the dielectric material being in a recess of the bottom electrode, the dielectric material having a height greater than a thickness of the MTJ and less than a stack height;

a dielectric layer over the stack and the dielectric material;

a capping layer conformally over the stack and the dielectric material, the capping layer having a middle portion and edge portions, the middle portion being thicker than the edge portions, the middle portion overlying a top surface of the bottom electrode and the edge portions adjoining sidewalls of the bottom electrode, the dielectric layer being over the capping layer; and

a conductive material extending through the dielectric layer and having an interface with the top electrode of the stack, the top electrode having a second width at the interface, the second width being not more than the first width, the conductive material having an upper portion with a width wider than the second width.

2. The MRAM device of claim 1 , wherein the dielectric material comprises a planarized top surface at the height.

3. The MRAM device of claim 1 , wherein the dielectric material is a spacer along the sidewall.

4. The MRAM device of claim 1 , wherein the capping layer adjoins the top surface of the bottom electrode.

5. The MRAM device of claim 1 , wherein the capping layer adjoins the bottom electrode at only the sidewalls of the bottom electrode.

6. The MRAM device of claim 1 , wherein the top electrode comprises a first top electrode and a second top electrode over the first top electrode, the first top electrode comprising a material different from the second top electrode.

7. The MRAM device of claim 1 , wherein the bottom electrode is electrically coupled to a conductive pattern in the substrate.

8. The MRAM device of claim 1 , wherein the conductive material is in a via extending to the top electrode.

9. A magnetoresistive random access memory (MRAM) device comprising:

a conductive pattern in a substrate;

a bottom electrode over the substrate and the conductive pattern, the bottom electrode being coupled to the conductive pattern;

a magnetic tunnel junction (MTJ) over the bottom electrode;

a top electrode over and having an interface with the MTJ, the top electrode having a continuous vertical sidewall from the interface to a top surface of the top electrode;

a dielectric material along a curved sidewall of the MTJ, a portion of the dielectric material being in a recess of the bottom electrode, the dielectric material having a height greater than a height of the interface of the top electrode and the MTJ and less than a height of the top surface of the top electrode;

a dielectric layer over the top surface of the top electrode and the dielectric material;

a capping layer conformally over the top surface of the top electrode and over the dielectric material, the capping layer having a middle portion and edge portions, the middle portion being thicker than the edge portions, the middle portion overlapping a top surface of the bottom electrode and the edge portions adjoining sidewalls of the bottom electrode, the dielectric layer being over the capping layer; and

a via extending through the dielectric layer to the top electrode, the via having an upper portion that is wider than a lower portion.

10. The MRAM device of claim 9 , wherein the dielectric material comprises a planarized top surface at the height.

11. The MRAM device of claim 9 , wherein the dielectric material is a spacer along the sidewall.

12. The MRAM device of claim 9 , wherein the capping layer adjoins the top surface of the bottom electrode.

13. The MRAM device of claim 9 , wherein the capping layer does not adjoin the bottom electrode at an upper surface of the bottom electrode.

14. A magnetoresistive random access memory (MRAM) device comprising:

a bottom electrode over a substrate;

a magnetic tunnel junction (MTJ) over the bottom electrode;

a top electrode over the MTJ, the top electrode and the MTJ being substantially coterminous;

a dielectric material forming a dielectric spacer along a curved sidewall of the MTJ, a portion of the dielectric material being in a recess of the bottom electrode, the dielectric spacer having a height greater than a thickness of the MTJ and less than a height of a top surface of the top electrode, the dielectric spacer having a convex outer sidewall;

a dielectric layer over the top surface of the top electrode and the dielectric spacer;

a capping layer conformally over the top surface of the top electrode and over the dielectric spacer, the capping layer having a middle portion and edge portions, the middle portion being thicker than the edge portions, the middle portion overlapping a top surface of the bottom electrode and the edge portions adjoining sidewalls of the bottom electrode, the dielectric layer being over the capping layer; and

a conductive material extending through the dielectric layer to the top surface of the top electrode, the conductive material having an upper portion that is wider than a lower portion.

15. The MRAM device of claim 14 , wherein the capping layer adjoins the top surface of the bottom electrode.

16. The MRAM device of claim 14 , wherein the conductive material is in a via extending to the top surface of the top electrode.

17. The MRAM device of claim 14 , wherein the top electrode comprises a first top electrode and a second top electrode over the first top electrode, the first top electrode comprising a material different from the second top electrode.