Ferromagnetic tunnel junction element and method of driving ferromagnetic tunnel junction element
Inactive Publication Date: 2011-07-07
III HLDG 3
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- Abstract
- Description
- Claims
- Application Information
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Benefits of technology
In this invention, it is preferable that the above-described ferromagnetic tunnel junction element be comprised by magnetic random access memory as a storage element. Magnetic random access memory enabling writing with a low current density has the advantage of reduced heat dissipation in addition to reducing power consumption. Further, it is preferable that the second ferromagnetic layer be of Permalloy. By using Permalloy, a soft magnetic material with high magnetic permeability, when the first ferromagnetic layer of the invention is for example a material having a large spontaneous magnetization, magnetization in the same direction occurs via the nonmagnetic layer, and a state having a smaller saturation magnetization than in the first ferromagnetic layer can be induced, which is preferable.
By means of this invention, an MTJ element with a small current value required for writing can be realized, and MRAM with low power consumption can be configured.
Problems solved by technology
Hence the problem arises that causing reversal of the magnetization of the ferromagnetic free layer 2, that is, writing data, becomes difficult, and this constitutes a major engineering issue for MRAMs.
However in MRAM which adopts the magnetic field writing method, and even in MRAM which adopts the spin-transfer magnetization reversal technique (spin-transfer magnetization reversal MRAM), there is the problem that the current necessary for writing is too large.
In magnetic field writing MRAM as well, reduction of the current value necessary for writing is a common problem.
Method used
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example 1
PRACTICAL EXAMPLE 1
This practical example is an MTJ element 1, which is an MTJ element of the invention in which Ni80Fe20 (Permalloy) is adopted as the low-magnetization ferromagnetic layer (second ferromagnetic layer). FIG. 1 shows the cross-sectional configuration of the MTJ element 1 of this practical example; below, a method of fabrication of the MTJ element of this practical example is described. As shown in the figure, the MTJ element 1 of this practical example has a configuration in which are layered, in order, Si / SiO2 / Ta (5 nm) / Ru (10 nm) / Ir25Mn75 (10 nm) / Co70Fe30 (3 nm) / Ru (0.8 nm) / Co40Fe40B20 (3 nm) / MgO (2 nm) / Co60Fe20B20 (3 nm) / Ru (1.4 nm) / Ni80Fe20 (3 nm) / Ta (10 nm). Of these, Si / SiO2 means a thermally oxidized Si substrate (Si wafer). The IrMn layer is a layer to apply an antiferromagnetic exchange bias to the ferromagnetic fixed layer 4 (CoFe ferromagnetic layer / Ru intermediate layer / CoFeB ferromagnetic layer), and acts to fix the magnetization direction of the ferroma...
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In a tunnel junction element having a ferromagnetic free layer, an insulating layer and a ferromagnetic fixed layer, in order to reduce the current necessary for spin-transfer magnetization reversal operation in the tunnel junction element, the ferromagnetic free layer comprises first and second ferromagnetic layers, a nonmagnetic metal layer is provided between these ferromagnetic layers, the nonmagnetic metal layer is such that magnetic coupling is preserved between the first and second ferromagnetic layers, also such that there is no influence on the crystal growth of the first and second ferromagnetic layers, the first ferromagnetic layer and the second ferromagnetic layer are placed such that the first ferromagnetic layer is in contact with the insulating layer, and the second ferromagnetic layer has a smaller magnetization than the first ferromagnetic layer.
Description
TECHNICAL FIELD This invention relates to a ferromagnetic tunnel junction (MTJ) element serving as a storage element used in magnetic random access memory (MRAM), to a memory device using such an element, and to a method of driving a ferromagnetic tunnel junction element, and in particular relates to an MTJ element with the improved write characteristics.BACKGROUND ARTMagnetic random access memory (MRAM) is memory using an MTJ element 1, the basic configuration of which is a layered structure of a ferromagnetic free layer 2 / insulating layer 3 / ferromagnetic fixed layer 4, as shown in FIG. 2. In an MTJ element 1, a phenomenon (the tunnel magnetoresistance or TMR effect) is observed in which the resistance value for tunnel current flowing in the perpendicular direction between layers is different according to whether the direction of the magnetizations of the set of the ferromagnetic free layer 2 and the ferromagnetic fixed layer 4 are parallel or antiparallel. Thus by applying this ph...
Claims
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Patent Timeline
Login to View More IPC IPC(8): H01L29/82
CPCB82Y25/00G11C11/16H01F10/3254H01F10/3295H01L27/228H01L43/08H01F10/3268G11C11/161H10B61/22H10N50/10H10B61/00H10N50/80H10N50/85
InventorONO, TAKUYA
OwnerIII HLDG 3