Free layer with high thermal stability for magnetic device applications by insertion of a boron dusting layer
First Claim
1. A multilayer stack with thermal stability to at least 400°
- C. in a magnetic device, comprising;
(a) a reference layer;
(b) a free layer with perpendicular magnetic anisotropy (PMA) and having a top surface and a bottom surface;
(c) a tunnel barrier layer formed between the reference layer and free layer; and
(d) at least one dusting layer made of boron or a boron alloy having a B content greater than about 85 atomic % that contacts the bottom surface of the free layer in a bottom spin valve configuration, or the at least one dusting layer contacts the top surface of the free layer in a top spin valve configuration.
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Accused Products
Abstract
A boron or boron containing dusting layer such as CoB or FeB is formed along one or both of top and bottom surfaces of a free layer at interfaces with a tunnel barrier layer and capping layer to improve thermal stability while maintaining other magnetic properties of a MTJ stack. Each dusting layer has a thickness from 0.2 to 20 Angstroms and may be used as deposited, or at temperatures up to 400° C. or higher, or following a subsequent anneal at 400° C. or higher. The free layer may be a single layer of CoFe, Co, CoFeB or CoFeNiB, or may include a non-magnetic insertion layer. The resulting MTJ is suitable for STT-MRAM memory elements or spintronic devices. Perpendicular magnetic anisotropy is maintained in the free layer at temperatures up to 400° C. or higher. Ku enhancement is achieved and the retention time of a memory cell for STT-MRAM designs is increased.
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Citations
17 Claims
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1. A multilayer stack with thermal stability to at least 400°
- C. in a magnetic device, comprising;
(a) a reference layer; (b) a free layer with perpendicular magnetic anisotropy (PMA) and having a top surface and a bottom surface; (c) a tunnel barrier layer formed between the reference layer and free layer; and (d) at least one dusting layer made of boron or a boron alloy having a B content greater than about 85 atomic % that contacts the bottom surface of the free layer in a bottom spin valve configuration, or the at least one dusting layer contacts the top surface of the free layer in a top spin valve configuration. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- C. in a magnetic device, comprising;
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8. A magnetic tunnel junction (MTJ) with thermal stability to at least 400°
- C., comprising;
(a) a seed layer formed on a substrate; (b) a reference layer; (c) a free layer with perpendicular magnetic anisotropy (PMA) and having a top surface and a bottom surface; (d) a tunnel barrier layer formed between the reference layer and free layer; and (e) a first dusting layer and a second dusting layer made of boron or a boron alloy having a B content greater than about 85 atomic % wherein the first dusting layer contacts the bottom surface of the free layer and the second dusting layer contacts the top surface of the free layer. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
- C., comprising;
Specification