MgO tunnel barriers and method of formation
AssigneeInternational Business Machines Corporation
InventorStuart Stephen Papworth Parkin
Life of this patent
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Abstract
MgO tunnel barriers are formed by depositing a thin layer of Mg on a suitable underlayer, and then directing oxygen and additional Mg towards the Mg layer. The oxygen reacts with the additional Mg and the Mg in the Mg layer to form a MgO tunnel barrier that enjoys excellent tunneling characteristics. The MgO tunnel barriers so formed may be used in magnetic tunnel junctions having tunneling magnetoresistance (TMR) values of greater than 100%. The highest TMR values are observed for junctions that have been annealed and that have a (100) crystallographic orientation.
Claims52
A method, comprising:
- depositing Mg onto a surface of an underlayer to form a Mg layer thereon, wherein the surface is selected to be substantially free of oxide, and the underlayer includes at least one layer of magnetic material selected from the group consisting of ferromagnetic materials and ferrimagnetic materials;
- directing additional Mg, in the presence of oxygen, towards the Mg layer to form a MgO tunnel barrier in contact with the underlayer, the oxygen reacting with the additional Mg and the Mg layer;
- forming an overlayer on the MgO tunnel barrier to form a magnetic tunnel junction, wherein the overlayer includes a magnetic material selected from the group of materials consisting of ferromagnetic materials and ferrimagnetic materials;
- and
- annealing the tunnel junction to yield a tunnel magnetoresistance of greater than 100% at room temperature,
- wherein the magnetic material of the underlayer is at least partially (100) oriented.
A method, comprising:
- providing a ferromagnetic underlayer having a surface that is substantially free of oxide;
- forming a Mg layer on the surface to both protect the underlayer from oxidation and to wet the underlayer;
- directing oxygen and additional Mg onto the Mg layer to form a MgO tunnel barrier that is in contact with the underlayer;
- forming a ferromagnetic overlayer over the MgO tunnel barrier to form a magnetic tunnel junction;
- and
- annealing the tunnel junction, so that its tunneling magnetoresistance is greater than 100% at room temperature,
- wherein the ferromagnetic underlayer is at least partially (100) oriented.
A method, comprising:
- depositing Mg onto a surface of an underlayer to form a Mg layer thereon, wherein the surface is substantially free of oxide;
- directing additional Mg, in the presence of oxygen, towards the Mg layer to form a MgO tunnel barrier in contact with the underlayer, the oxygen reacting with the additional Mg and the Mg layer;
- and
- annealing the MgO tunnel barrier to increase the spin polarization of tunneling current passing through the MgO tunnel barrier.
Dependencies are inferred from the claim text.