Magnetic Memory and Manufacturing Method For the Same
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Abstract
The present invention to provide a new technique to reduce a variation in switching field of a magnetization free layer in a magnetic memory. The magnetic memory according to the present invention includes a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; and a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction.
75 Citations
24 Claims
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1. (canceled)
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2. (canceled)
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3. (canceled)
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4. (canceled)
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5. (canceled)
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6. (canceled)
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7. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; and a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction; a space layer; and a base layer having a magnetization pinned layer that is provided to be opposite to said magnetization free layer with respect to said spacer layer, wherein said stress inducing structure comprises a stress inducing layer that is provided separately from said base layer. - View Dependent Claims (8, 9)
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10. A magnetic memory comprising;
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a magnetization free layer including a ferromagnetic layer having a shape dependent magnetic anisotropy in a first direction and a magnetic strain constant is positive; a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction; and a spacer layer connected with said magnetization free layer, wherein said stress inducing structure comprises a base layer having a magnetization pinned layer that is provided to be opposite to said magnetization free layer with respect to said spacer layer.
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11. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction; a spacer layer; and a base layer having a magnetization pinned layer that is provided to be opposite to said magnetization free layer with respect to said spacer layer, wherein said base layer comprises a protrusion formed to extend in a third direction oblique to the first direction and to protrude in the third direction, and said protrusion functions as said stress inducing structure.
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12. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction; wherein said stress inducing structure comprises; a lower wiring provided between said magnetization free layer and said substrate to extend in the first direction, and supplied with a write current to reverse a direction of magnetization of said magnetization free layer.
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13. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is negative; a stress inducing structure configured to apply a compression stress to said magnetization free layer in a same direction as the first direction; wherein said stress inducing structure comprises; a lower wiring provided between said magnetization free layer and said substrate to extend in a second direction orthogonal to the first direction, and supplied with a write current to reverse a direction of magnetization of said magnetization free layer.
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14. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape dependent magnetic anisotropy in a first direction and a magnetic strain constant is positive; a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction; and a wiring provided to extend in a direction different from the first direction and supplied with a write current to reverse a direction of magnetization of said magnetization free layer; and another stress inducing structure configured to apply a stress to said magnetization free layer in a direction opposite to the direction of the stress applied by said stress inducing structure.
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15. magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction; wherein said magnetization free layer has a length d in the first direction, and a width W in a second direction orthogonal to the first direction, a ratio d/W is 2 or less, a ratio of a stress inducting anisotropy magnetic field of said magnetization free layer to a shape magnetic anisotropy magnetic field is 0.5 or more.
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16. A magnetic memory,
a magnetization free layer including a ferromagnetic layer having a shape dependent magnetic anisotropy in a first direction and a magnetic strain constant is positive; -
a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction; wherein there are a plurality of magnetic anistropis of said magnetization free layer, a stress inducing anisotropy magnetic field and a shape anisotropy magnetic field have no correlation, a parameter r defined from the following equation (1) by using an average value ASTR of stress inducing anisotropy magnetic fields HSTR, and an average value ASH of the shape anisotropy magnetic fields, and bSTR and bSH defined from the following equations (2a) and (2b) by using a standard deviation σ
STR of the stress inducing anisotropy magnetic fields, and a standard deviation σ
SH of the shape anisotropy magnetic fields meet the following equation (3);
r=ASH/(ASTR+ASH)
(1)
bSTR=σ
STR/ASTR
(2a)
bSH=σ
SH/ASH
(2b)
r=bST2/(bSTR2+bSH2)
(3)
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17. A magnetic memory comprising a magnetization free layer having a plurality of magnetic anistropis,
wherein anisotropy magnetic fields generated based on two magnetic anisotropies selected from a stress inducing anisotropy, a stress inducing anisotropy and a crystal magnetic anisotropy of a magnetization free layer have no correlation, a parameter r defined from the following equation (1′ - ) by using an average value AX of anisotropic magnetic fields resulting from one of the magnetic anisotropies, and an average value AY of the anisotropic magnetic fields resulting from the other of the magnetic anisotropies, and bX and bY defined from the following equations (2a′
) and (2b′
), by using a standard variation bST of a stress inducing anisotropic magnetic fields and a standard variation bSH of a shape anisotropic magnetic fields, meet the following equation (3);
r=AY/(AX+AY)
(1′
)
bX=σ
X/AX
(2a′
bY≃
σ
Y/AY
(2b′
)
r≃
bX2/(bX2+bY2)
(3)
- ) by using an average value AX of anisotropic magnetic fields resulting from one of the magnetic anisotropies, and an average value AY of the anisotropic magnetic fields resulting from the other of the magnetic anisotropies, and bX and bY defined from the following equations (2a′
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18. A magnetic memory comprising;
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is negative; a stress inducing structure configured to apply a compression stress to said magnetization free layer in a same direction as the first direction; a spacer layer; and a base layer having a magnetization pinned layer that is provided to be opposite to said magnetization free layer with respect to said spacer layer, wherein said stress inducing structure comprises a stress inducing layer that is provided separately from said base layer. - View Dependent Claims (19, 20)
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21. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is negative; a stress inducing structure configured to apply a compression stress to said magnetization free layer in a same direction as the first direction; a spacer layer connected with said magnetization free layer, wherein said stress inducing structure comprises a base layer having a magnetization pinned layer that is provided to be opposite to said magnetization free layer with respect to said spacer layer.
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22. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is negative; a stress inducing structure configured to apply a compression stress to said magnetization free layer in a same direction as the first direction; a spacer layer; and a base layer having a magnetization pinned layer that is provided to be opposite to said magnetization free layer with respect to said spacer layer, wherein said base layer comprises a protrusion formed to extend in a third direction oblique to the first direction and to protrude in the third direction, and said protrusion functions as said stress inducing structure.
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23. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is negative; a stress inducing structure configured to apply a compression stress to said magnetization free layer in a same direction as the first direction; a wiring provided to extend in a direction different from the first direction and supplied with a write current to reverse a direction of magnetization of said magnetization free layer; and another stress inducing structure configured to apply a stress to said magnetization free layer in a direction opposite to the direction of the stress applied by said stress inducing structure.
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24. A magnetic memory comprising:
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a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is negative; and a stress inducing structure configured to apply a compression stress to said magnetization free layer in a same direction as the first direction, wherein said magnetization free layer has a length d in the first direction, and a width W in a second direction orthogonal to the first direction, a ratio d/W is 2 or less, a ratio of a stress inducting anisotropy magnetic field of said magnetization free layer to a shape magnetic anisotropy magnetic field is 0.5 or more.
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Specification