Spin-transfer mram structure and methods
AssigneeFreescale Semiconductor, Inc.
InventorsFrederick B. Mancoff, Nicholas D. Rizzo
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Abstract
A spin-transfer MRAM bit includes a free magnet layer positioned between a pair of spin polarizers, wherein at least one of the spin polarizers comprises an unpinned synthetic antiferromagnet (SAF). The SAF may include two antiparallel fixed magnet layers separated by a coupling layer. To improve manufacturability, the layers of the SAF may be non-symmetrical (e.g., having different thicknesses or different inherent anisotropies) to assist in achieving proper alignment during anneal. The total magnetic moment of the SAF may be greater than that of the free magnet layer.
Claims20
A spin-transfer MRAM bit comprising a free magnet layer positioned between a first spin polarizer and a second spin polarizer, wherein at least one of the first and second spin polarizers comprises an unpinned synthetic antiferromagnet (SAF).
A method for forming a spin-transfer MRAM bit, comprising:
- forming a first spin polarizer;
- forming a first nonmagnetic spacer layer over the first spin polarizer;
- forming a free magnet layer over the first nonmagnetic spacer layer;
- forming a second nonmagnetic spacer layer over the free magnet layer;
- and
- forming a second spin polarizer over the second nonmagnetic spacer layer;
- wherein the step of forming a first spin polarizer or the step of forming the second spin polarizer includes forming an unpinned synthetic antiferromagnet (SAF).
An MRAM device comprising a plurality of spin-transfer MRAM bits, wherein each spin-transfer MRAM bit comprises a free magnet layer positioned between a first spin polarizer and a second spin polarizer, and wherein at least one of the first and second spin polarizers comprises an unpinned synthetic antiferromagnet (SAF).
Dependencies are inferred from the claim text.