Nec Corporation

Hisao Matsutera

Atsushi Kamijo

Masafumi Nakada

Hisanao Tsuge

Nobuyuki Ishiwata

Kazuhiko Hayashi

Keishi Ohashi

Yuji Tsukamoto

Tsutomu Ishi

Kunihiko Ishihara

Jun-Ichi Fujikata

Hiroaki Honjou

Ishiwata Nobuyuki

Tadahiko Sugibayashi

Kaoru Mori

Noboru Sakimura

Takeshi Honda

Tetsuhiro Suzuki

Kenichi Shimura

Hideaki Numata

In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.

Magnetoresistive effect transducer having longitudinal bias layer and control layer directly connected to free layer

A technique is provided in which an offset magnetic field of a memory cell of a MRAM is reduced more effectively. The MRAM of the present invention is composed of a free layer () which has a reversible free spontaneous magnetization, a fixed layer () which has fixed spontaneous magnetization, and a spacer layer () formed of non-magnetic interposed between the free layer () and the fixed layer (). The fixed layer () is formed such that orange peel effect and magneto-static coupling effect does not substantially influence on the free layer ().

Magnetic random access memory

An improved magnetic random access memory (MRAM) has two sets of signal lines where each set is substantially perpendicular to the other, and memory cells located at the intersections of the signal lines. Each memory cell has a magneto-resistant element containing a magnetization layer whose magnetic characteristics change depending on the intensity of the magnetic field applied. A desired magnetic field can be applied to any cell by supplying appropriate write currents to the signal lines intersecting at that cell. The relationship between applied magnetic fields, two different threshold function values, and four different magnetic fields that result at each cell is disclosed. Better performance, namely, improved selectivity and a more stable write operation, results.

In an aspect of the present invention, a magnetic random access memory includes a substrate, a MTJ (Magnetic tunnel Junction) device formed above the substrate, a first wiring line formed above the substrate, and a second wiring line formed above the substrate. The MTJ device includes a pinned ferromagnetic layer which has a pinned magnetization, a free ferromagnetic lamination layer, and a tunnel barrier layer interposed between the pinned ferromagnetic layer and the free ferromagnetic lamination layer. The free ferromagnetic lamination layer includes a first ferromagnetic layer coupled to the tunnel barrier layer and having a reversible first magnetization, a second ferromagnetic layer which has and a second magnetization whose direction is opposite to a direction of the first magnetization, the second magnetization being reversible, and a non-magnetic conductive layer provided between the first ferromagnetic layer and the second ferromagnetic layer and having a sheet resistance lower than sheet resistances of the first ferromagnetic layer and the second ferromagnetic layer. A write current is supplied the free ferromagnetic lamination layer through one of the first wiring line and the second wiring line to reverse the first magnetization and the second magnetization, and the other of the first wiring line and the second wiring line receives the supplied write current from the free ferromagnetic lamination layer.

Magnetic random access memory, and production method therefor

Magnetoresistive effect transducer having longitudinal bias layer directly connected to free layer

A magneto-resistance effect (&ldquo;MR&rdquo;) type composite head includes a reproduction head with an MR element arranged between a first and a second magnetic shield; and a recording head arranged adjacent to the reproduction head so as to use the second magnetic shield as a first magnetic pole film and having a second magnetic pole film opposing to the first magnetic pole via a magnetic gap; the MR element includes a center region including a ferromagnetic tunnel junction magneto-resistance effect film having a first ferromagnetic layer and a second ferromagnetic layer for generating a magneto-resistance effect using the first and the second magnetic shields as electrodes so that a current flows in an almost vertical direction between the first and the second magnetic shields; a tunnel barrier layer provided between the first and the second ferromagnetic layer; and an end region arranged to sandwich the center region from both sides for /applying a bias magnetic field to the center region.

Magneto-resistance effect type composite head and production method thereof

A magneto-resistive element comprises a first electrode, a magneto-resistive layer formed on the first electrode in which resistance is changed in accordance with magnetic field, and a second electrode layer formed on the magneto-resistive layer. The magneto-resistive layer has a first magnetic layer formed on the first electrode, a non-magnetic layer formed on the first magnetic layer, and a second magnetic layer formed on the non-magnetic layer. The average surface roughness of the first electrode is equal to or smaller than 0.3 nm. Since the first electrode has such the small average surface roughness, the non-magnetic layer formed on the first electrode layer is flattened, thus, current leakage is prevented. The first electrode is made of at least one of Ta, Zr, Ti, Hf, W, Mo, Y, V, Nb, Au, Ag, Pd, and Pt which has strong bond strength. Since the first electrode has strong bond strength, exfoliation of the first electrode from the layers contacting the first electrode does not occur.

Magneto-resistive element and magnetic head for data writing/reading

The present invention provides a magnetic tunnel junction device for an external magnetic field sensor. The device comprises a stack of multi-layers, which include a first antiferromagnetic pinning layer, a ferromagnetic free layer, a tunneling barrier layer, a ferromagnetic pinned layer, and a second antiferromagnetic pinning layer. The first pinning layer has a first pinning field, which pins a magnetization of the free layer in a track width direction. The second pinning layer has a second pinning field, which pins a magnetization of the pinned layer in a direction in the plane of the stacked layers of the magnetic tunnel junction, along the applied external magnetic field direction.

Magnetic tunnel junction elements and their fabrication method

The present invention provides a magneto-resistance effect (hereinafter, referred to as MR) type composite head. The head includes a reproduction head including an MR element arranged between a first and a second magnetic shield; and a recording head arranged next to the reproduction head so as to use the second magnetic shield as a first magnetic pole film and having a second magnetic pole film opposing to the first magnetic pole via a magnetic gap; the MR element including: a center region including a ferromagnetic tunnel junction magneto-resistance effect film (hereinafter, referred to as a TMR film) having: a first ferromagnetic layer and a second ferromagnetic layer for generating a magneto-resistance effect using the first and the second magnetic shields as electrodes so that a current flows in a an almost vertical direction between the first and the second magnetic shields; and a tunnel barrier layer provided between the first and the second ferromagnetic layer; and an end region arranged to sandwich the center region from both sides for applying a bias magnetic field to the center region.

There is provided a method of fabricating a ferromagnetic tunnel junction device, including the steps of (a) forming a first ferromagnetic layer on a substrate, (b) forming a tunnel barrier layer on the first ferromagnetic layer, (c) forming a second ferromagnetic layer on the tunnel barrier layer, (d) mechanically polishing end surfaces of the first ferromagnetic layer, the tunnel barrier layer, and the second ferromagnetic layer, and (e) etching the surfaces of the first ferromagnetic layer, the tunnel barrier layer, and the second ferromagnetic layer. The method provides a ferromagnetic tunnel junction device having a height defined with high accuracy, and including a tunnel barrier layer keeping first and second ferromagnetic layers in electrical isolation with each other.

Growing community of inventors

Tokyo, Japan

Hisao Matsutera