Capping structure for enhancing dR/R of the MTJ device
First Claim
1. A method of forming an MTJ element on a substrate, comprising:
- (a) sequentially forming a seed layer, an AFM layer, a pinned layer, and a tunnel barrier layer on a substrate;
(b) forming a moderate spin polarization free layer on the tunnel barrier layer; and
(c) forming a capping layer on said moderate spin polarization free layer wherein said capping layer is comprised of a lower inter-diffusion barrier layer comprised of Ru that contacts said moderate spin polarization free layer, a middle oxygen gettering layer made of Ta, and an oxidation resistant upper metal layer formed on the middle oxygen gettering layer, said oxidation resistant upper metal layer is comprised of Ru and has a top surface that is essentially planar and all layers in said capping layer that has a Ru/Ta/Ru configuration have substantially the same width.
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Abstract
An MTJ in an MRAM array or in a TMR read head is comprised of a capping layer with a lower inter-diffusion barrier layer, an intermediate oxygen gettering layer, and an upper metal layer that contacts a top conductor. The composite capping layer is especially useful with a moderate spin polarization free layer such as a NiFe layer with a Fe content of about 17.5 to 20 atomic %. The capping layer preferably has a Ru/Ta/Ru configuration in which the lower Ru layer is about 10 to 30 Angstroms thick and the Ta layer is about 30 Angstroms thick. As a result, a high dR/R of about 40% is achieved with low magnetostriction less than about 1.0 E−6 in an MTJ in an MRAM array. Best results are obtained with an AlOx tunnel barrier layer formed by an in-situ ROX process on an 8 to 10 Angstrom thick Al layer.
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Citations
15 Claims
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1. A method of forming an MTJ element on a substrate, comprising:
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(a) sequentially forming a seed layer, an AFM layer, a pinned layer, and a tunnel barrier layer on a substrate; (b) forming a moderate spin polarization free layer on the tunnel barrier layer; and (c) forming a capping layer on said moderate spin polarization free layer wherein said capping layer is comprised of a lower inter-diffusion barrier layer comprised of Ru that contacts said moderate spin polarization free layer, a middle oxygen gettering layer made of Ta, and an oxidation resistant upper metal layer formed on the middle oxygen gettering layer, said oxidation resistant upper metal layer is comprised of Ru and has a top surface that is essentially planar and all layers in said capping layer that has a Ru/Ta/Ru configuration have substantially the same width. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification