Magnetic memory and method of manufacturing magnetic memory
According to one embodiment, a magnetic memory includes a first metal layer including a first metal, a second metal layer on the first metal layer, the second metal layer including a second metal which is more easily oxidized than the first metal, the second metal layer having a first sidewall portion which contacts the first metal layer, and the second metal layer having a second sidewall portion above the first sidewall portion, the second sidewall portion which steps back from the first sidewall portion, a magnetoresistive element on the second metal layer, a third metal layer on the magnetoresistive element, and a first material which contacts a sidewall portion of the magnetoresistive element and the second sidewall portion of the second metal layer, the first material including an oxide of the second metal.
1. A magnetic memory comprising:
a first metal layer containing a first metal material;
a second metal layer on the first metal layer, the second metal layer containing a second metal material which is more easily oxidized than the first metal material, the second metal layer comprising a lower portion contacting the first metal layer and having a first sidewall portion, and an upper portion having a second sidewall portion which is located inward with respect to the first sidewall portion;
a magnetoresistive element on the second metal layer;
a third metal layer on the magnetoresistive element;
a first material layer which contacts a sidewall portion of the magnetoresistive element and the second sidewall portion of the second metal layer, the first material layer containing the same metal material as the second metal material;
a spacer layer covering the first material layer; and
a second material layer which contacts a sidewall portion of the spacer layer and the first sidewall portion of the second metal layer, the second material layer containing the same metal material as the first metal material.
2. The memory of claim 1 , further comprising:
a protection layer covering the first metal layer, the second metal layer, the magnetoresistive element, the third metal layer, the first material layer, the spacer layer, and the second material layer, wherein the protection layer comprises a nitride.
3. The memory of claim 1 , wherein the second metal material has a standard electrode potential lower than a standard electrode potential of the first metal material.
4. The memory of claim 1 , wherein the first material layer includes an oxide of the second metal material.
5. The memory of claim 1 , wherein the second material layer includes an oxide of the first metal material.
6. The memory of claim 1 , wherein each of the first and second material layers has a thickness of 1 nm or less in a direction which is parallel to an upper surface of the first metal layer.
7. The memory of claim 1 , wherein each of the first and second sidewall portions has a tilt of 15° or less with respect to an axis which is perpendicular to an upper surface of the first metal layer.
8. The memory of claim 1 , wherein a width from the first sidewall portion to the second sidewall portion is substantially equal to a width of the spacer layer in a direction which is parallel to an upper surface of the first metal layer.
9. The memory of claim 1 , wherein the magnetoresistive element has a size less than a size of the first metal layer in a direction which is parallel to an upper surface of the first metal layer.
10. The memory of claim 1 , wherein the second metal layer has a size less than a size of the first metal layer in a direction which is parallel to an upper surface of the first metal layer.
11. The memory of claim 1 , wherein the first metal layer is a contact plug which contacts a source/drain region of a select transistor.
12. The memory of claim 1 , wherein the first metal material includes one of W, Ta, Ru, and Ti.
13. The memory of claim 1 , wherein the second metal material includes one of Al, Be, Mg, Ca, Sr, Ba, Sc, Y, La, Zr, and Hf.
14. The memory of claim 1 , further comprising an underlying layer between the second metal layer and the magnetoresistive element, the underlying layer including one of MgO, AlN, MgN, ZrN, NbN, SiN, and AlTiN.
15. The memory of claim 1 , wherein the magnetoresistive element comprises a first magnetic layer on the second metal layer, a nonmagnetic layer on the first magnetic layer, and a second magnetic layer on the nonmagnetic layer.
16. The memory of claim 15 , wherein each of the first and second magnetic layers has a residual magnetization in a direction in which the first and second magnetic layers are stacked.
17. The memory of claim 15 , wherein the first magnetic layer has a variable magnetization, and the second magnetic layer has an invariable magnetization.
18. The memory of claim 17 , wherein the magnetoresistive element comprises a shift cancelling layer provided between the second magnetic layer and the third metal layer, and the shift cancelling layer having an invariable magnetization which is contrary to the magnetization of the second magnetic layer.