Magnetic memory and method of manufacturing the same

1. A magnetic memory comprising

at least one memory cell comprising a magnetoresistive element as a memory element, first and second electrodes that energize the magnetoresistive element, and an insulating film covering the magnetoresistive element,

the magnetoresistive element comprising: a first magnetic layer having a variable magnetization direction perpendicular to a film plane; a tunnel barrier layer on the first magnetic layer; and a second magnetic layer on the tunnel barrier layer, and having a fixed magnetization direction perpendicular to the film plane,

the first magnetic layer comprising: a first region; and a second region outside the first region so as to surround the first region, and having a smaller perpendicular magnetic anisotropy energy than that of the first region,

the second magnetic layer comprising: a third region; and a fourth region outside the third region so as to surround the third region, and having a smaller perpendicular magnetic anisotropy energy than that of the third region,

wherein a mean size of the second region in a film thickness direction is larger than a mean size of the fourth region in the film thickness direction.

2. The magnetic memory according to claim 1 , wherein

the second region comprises an element contained in the first region, and another element different from the element; and

the fourth region comprises an element contained in the third region, and the another element.

3. The magnetic memory according to claim 1 , wherein a diameter of the first region is equal to or smaller than a diameter of the third region.

4. The magnetic memory according to claim 1 , wherein the another element is at least one of N, He, F, O, Si, B, C, Zr, Tb, and Ti.

5. The magnetic memory according to claim 4 , wherein a concentration of the another element in the second and fourth regions is 1 atomic % or higher.

6. The magnetic memory according to claim 1 , further comprising

a third magnetic layer located on the opposite side of the second magnetic layer from the tunnel barrier layer, and having a magnetization direction that is perpendicular to the film plane and is the opposite of the magnetization direction of the second magnetic layer.

7. The magnetic memory according to claim 1 , wherein a mean size of the second region in a film thickness direction thereof is larger than a mean size of the fourth region in a film thickness direction thereof.

8. The magnetic memory according to claim 1 , wherein sidewalls of the first magnetic layer, sidewalls of the tunnel barrier layer, and part of sidewalls of the second magnetic layer form a tapered shape that becomes narrower in cross-section from the first magnetic layer toward the second magnetic layer.

9. The magnetic memory according to claim 1 , wherein the following relationship is satisfied in the second region:

Ku≦ 2π Ms 2

where Ku represents the perpendicular magnetic anisotropy energy of the second region, and Ms represents saturation magnetization of the second region.

10. The magnetic memory according to claim 1 , wherein

the first and third regions are electrically active, and

the second and fourth regions are electrically inactive.

11. The magnetic memory according to claim 1 , wherein

the second magnetic layer comprises a first portion formed on the tunnel barrier layer, and a second portion formed on the first portion, the second portion having a cross-sectional area increasing from an upper face of the second magnetic layer toward the first portion, the cross-sectional area being in a plane perpendicular to the film plane.

12. The magnetic memory according to claim 1 , further comprising:

a first interconnect electrically connected to the first electrode; and

a second interconnect electrically connected to the second electrode.

13. The magnetic memory according to claim 12 , further comprising

a select transistor provided between the first electrode and the first interconnect or between the second electrode and the second interconnect.