Semiconductor memory device with magnetoresistive element
According to one embodiment, a semiconductor memory device includes a magnetoresistive element and an insulating layer. The magnetoresistive element includes a first magnetic layer, a nonmagnetic layer, and a second magnetic layer and. The magnetoresistive element is capable of storing data according to a direction of magnetization in the first magnetic layer. The insulating layer covers a side surface of the magnetoresistive element. The first magnetic layer includes a first region and a second region. Each of the first and second regions includes a magnetic material and a nonmagnetic material. A concentration ratio of the nonmagnetic material to the magnetic material is higher in the second region than in the first region.
1. A semiconductor memory device comprising:
a magnetoresistive element provided over a semiconductor substrate and including a first magnetic layer, a nonmagnetic layer, and a second magnetic layer, the magnetoresistive element being capable of storing data according to a direction of magnetization in the first magnetic layer; and
an insulating layer which covers a side surface of the magnetoresistive element,
wherein:
the first magnetic layer includes a first region and a second region provided between the insulating layer and the first region,
the first and second regions have magnetization,
each of the first and second regions includes a magnetic material and a nonmagnetic material, and
a concentration ratio of the nonmagnetic material to the magnetic material is higher in the second region than in the first region.
2. The device according to claim 1 , wherein
the magnetic materials in the first and second regions include at least one of cobalt (Co), iron (Fe), and nickel (Ni).
3. The device according to claim 1 , wherein
the nonmagnetic materials in the first and second regions contain boron (B), and
a concentration ratio of the boron to the magnetic material is higher in the second region than in the first region.
4. The device according to claim 1 , wherein
the insulating layer contains at least one of aluminum (Al), silicon (Si), and magnesium (Mg).
5. The device according to claim 1 , wherein
the nonmagnetic material in the second region includes at least one of boron (B), nitrogen (N), phosphorous (P), and carbon (C).
6. The device according to claim 1 , wherein
the first magnetic layer, the nonmagnetic layer, and the second magnetic layer are laminated in order above the semiconductor substrate.
7. The device according to claim 1 , wherein
the second magnetic layer, the nonmagnetic layer, and the first magnetic layer are laminated in order above the semiconductor substrate.
8. The device according to claim 1 , wherein
saturation magnetization is lower in the second region than in the first region.
9. The device according to claim 1 , wherein
the nonmagnetic material in the second region contains boron (B), and a concentration ratio of the boron to the magnetic material in the second region decreases from an interface between the second region and the insulating layer toward an interface between the second region and the first region.
10. The device according to claim 1 , wherein
the insulating layer contains at least one of boron nitride (BN), boron oxide (B 2 O 3 ), boron (B), silicon boron nitride (SiBN), and silicon boron oxide (SiBO).
11. The device according to claim 1 , wherein
the nonmagnetic material in the second region and the insulating layer contain at least one of boron (B), carbon (C), nitrogen (N), phosphorous (P), silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), chromium (Cr), hafnium (Hf), tantalum (Ta), zirconium (Zr), and scandium (Sc).
12. The device according to claim 1 , wherein:
the magnetoresistive element further includes:
a first conductive layer provided below the first magnetic layer; and
a first layer provided between the insulating layer and the second region, and
the first conductive layer and the first layer contain at least one of calcium boride (CaB), scandium boride (ScB), magnesium boride (MgB), silicon boride (SiB), aluminum boride (AIB), tantalum boride (TaB), zirconium boride (ZrB), niobium boride (NbB), hafnium boride (HfB), and chromium boride (CrB).
13. The device according to claim 1 , wherein:
the magnetoresistive element further includes:
a first conductive layer provided below the first magnetic layer; and
a first layer provided between the insulating layer and the second region, and
the first conductive layer and the first layer contain a same element.
14. The device according to claim 1 , wherein
the second magnetic layer contains at least one of cobalt platinum (CoPt), cobalt nickel (CoNi), cobalt palladium (CoPd), a multilayer film of Co and Pt, and a multilayer film of Co and Pd.
15. The device according to claim 1 , wherein
the nonmagnetic layer contains at least one of magnesium oxide (MgO) and aluminum oxide (Al 2 O 3 ).
16. The device according to claim 6 , wherein:
the magnetoresistive element further includes:
a spacer layer provided on the second magnetic layer; and
a third magnetic layer provided on the spacer layer, and
a direction of magnetization in the second magnetic layer is opposite to a direction of magnetization in the third magnetic layer.
17. The device according to claim 1 , wherein
the nonmagnetic materials in the first and second regions contain at least one of boron (B), carbon (C), nitride (N), phosphorous (P), silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), chromium (Cr), hafnium (Hf), tantalum (Ta), zirconium (Zr), and scandium (Sc).
18. The device according to claim 1 , wherein
the insulating layer contains at least one of silicon nitride (SiN), aluminum nitride (AIN), aluminum oxide (Al 2 O 3 ), silicon carbide (SiC), silicon oxynitride (SiON), silicon carbonitride (SiCN), magnesium oxide (MgO), and DLC (diamond like carbon).
19. The device according to claim 1 , wherein
the magnetic materials in the first and second regions contain at least one of cobalt iron boron (CoFeB) and iron boron (FeB).