Headway Technologies, Incorporated

Applied Spintronics, Inc.

Magic Technologies, Inc.

Pokang Wang

Yimin Guo

Tai Min

Mao-Min Chen

Cherng-Chyi Han

Xizeng Shi

Min Li

Cherng Chyi Han

Xi Zeng Shi

Otto Vogeli

Moris Musa Dovek

Yue Liu

Hsu Kai Yang

Rodney E Lee

Rod Lee

Daniel Gerard Abels

A CPP MTJ or GMR read sensor is provided in which the free layer is self-stabilized by a magnetization in a circumferential vortex configuration. This magnetization permits the pinned layer to be magnetized in a direction parallel to the ABS plane, which thereby makes the pinned layer directionally more stable as well. The lack of lateral horizontal bias layers or in-stack biasing allows the formation of closely configured shields, thereby providing protection against side-reading. The vortex magnetization is accomplished by first magnetizing the free layer in a uniform vertical field, then applying a vertical current while the field is still present.

CPP magnetic recording head with self-stabilizing vortex configuration

A magnetic sensor for identifying small superparamagnetic particles bonded to a substrate contains a regular orthogonal array of MTJ cells formed beneath that substrate. A magnetic field imposed on the particle, perpendicular to the substrate, induces a magnetic field that has a component within the MTJ cells that is along the plane of the MTJ free layer. If that free layer has a low switching threshold, the induced field of the particle will create resistance changes in a group of MTJ cells that lie beneath it. These resistance changes will be distributed in a characteristic formation or signature that will indicate the presence of the particle. If the particle's field is insufficient to produce the free layer switching, then a biasing field can be added in the direction of the hard axis and the combination of this field and the induced field allows the presence of the particle to be determined.

Devices using addressable magnetic tunnel junction array to detect magnetic particles

An MTJ MRAM cell is formed between ultra-thin orthogonal word and bit lines of high conductivity material whose thickness is less than 100 nm. Lines of this thickness produce switching magnetic fields at the cell free layer that are enhanced by a factor of approximately two for a given current. Because the lines require thinner depositions, there is no necessity of removing material by CMP during patterning and polishing. Therefore, there is a uniform spacing between the lines and the cell free layer.

Magnetic random access memory array with thin conduction electrical read and write lines

An MTJ MRAM cell is formed between or below an intersection of ultra-thin orthogonal word and bit lines of high conductivity material whose thickness is less than 100 nm. Lines of this thickness produce switching magnetic fields at the cell free layer that are enhanced by a factor of approximately two for a given current. The fabrication of a cell with such thin lines is actually simplified as a result of the thinner depositions because the fabrication process eliminates the necessity of removing material by CMP during patterning and polishing, thereby producing uniform spacing between the lines and the cell free layer.

The problem of increasing the output signal from a CCP-CPP GMR device without having it overheat has been overcome by placing materials that have different thermoelectric potentials on opposing sides of the spacer layer. Heat from the hot junction is removed at the substrate, which acts as a heat sink, resulting in a net local cooling of the confined current spacer layer, enabling it to operate at both higher input voltage increased reliability.

Method to increase CCP-CPP GMR output by thermoelectric cooling

A method is provided for forming a CPP MTJ or GMR read sensor in which the free layer is self-stabilized by a magnetization in a circumferential vortex configuration. This magnetization permits the pinned layer to be magnetized in a direction parallel to the ABS plane, which thereby makes the pinned layer directionally more stable as well. The lack of lateral horizontal bias layers or in-stack biasing allows the formation of closely configured shields, thereby providing protection against side-reading. The vortex magnetization is accomplished by first magnetizing the free layer in a uniform vertical field, then applying a vertical current while the field is still present.

Method of forming a CPP magnetic recording head with a self-stabilizing vortex configuration

An MTJ element is formed between orthogonal word and bit lines. The bit line is a composite line which includes a high conductivity layer and a soft magnetic layer under the high conductivity layer. During operation, the soft magnetic layer concentrates the magnetic field of the current and, due to its proximity to the free layer, it magnetically couples with the free layer in the MTJ. This coupling provides thermal stability to the free layer magnetization and ease of switching and the coupling may be further enhanced by inducing a shape or crystalline anisotropy into the free layer during formation.

Magnetic random access memory array with coupled soft adjacent magnetic layer

Problems such as thermal pole tip protrusion result from thermal mismatch between the alumina and pole material during the writing process. This, and similar problems due to inadequate heat dissipation, have been overcome by dividing the bottom shield into two pieces both of which sit on top of a non-magnetic heat sink. Heat generated by the coil during writing is transferred to the non-magnetic heat sink whence it gets transferred to the substrate. With this approach, the head not only benefits from less field disturbance due to the small shield but also improves heat dissipation from the additional heat sink.

Method to improve heat dissipation in a magnetic shield

One of the major requirements for higher frequency extendability is to reduce yoke length and inductance in order to have fast saturation. This has been accomplished by using a design that provides a cavity in the lower pole piece inside which is located at least two coils, one on top of the other. A process for manufacturing the device is also described.

High data rate writer with low resistance coil and short yoke

A method for forming an abutted junction GMR bottom spin valve sensor in which the free layer has a maximum effective length due to the elimination or minimization of bias layer and conducting lead layer overspreading onto the sensor element and the consequent reduction of current shunting. The overspreading is eliminated by forming a thin dielectric layer on the upper surface of the sensor element. When the biasing and conducting leads are formed on the abutted junction, they overspread onto this layer and the overspread can be removed by an ion-milling process during which the dielectric layer protects the sensor.

Method to make abutted junction GMR head without lead shunting

An MTJ MRAM cell is formed above or below an intersection of vertically separated, magnetically clad, ultra-thin orthogonal word and bit lines whose thickness is less than 100 nm. Lines of this thickness produce switching magnetic fields at the cell free layer that are enhanced by a factor of approximately two for a given current. The word and bit lines also include a soft magnetic layer of high permeability formed on their surfaces distal from the cell to improve the magnetic field still further. The fabrication of a cell with such thin lines is actually simplified as a result of the thinner depositions and eliminates the necessity of removing material by CMP during patterning and polishing, thereby producing uniform spacing between the lines and the cell free layer.

Magnetic random access memory array with proximate read and write lines cladded with magnetic material

An MTJ including the free layer and reference layer have a vortex magnetization state that is formed with a clockwise or counterclockwise rotation. The MTJ has a low aspect ratio elliptical shape and the magnetic layers have a dopant that is one of C, N, B, Zr, Ta, Pt, Nb, or Hf to facilitate the flux closure configuration. The vortex magnetization is induced by applying a reverse magnetic field in a direction opposite to the remnant magnetization in a magnetic layer. An anti-ferromagnetic layer is set in an AFM phase after the vortex state is induced in the adjacent reference layer. Switching the vortex state in the free layer involves applying a first field in a first direction to break the vortex and then applying a smaller second field in a reverse direction to a critical point where a vortex of opposite spin is induced.

Vortex magnetic random access memory

An MTJ MRAM cell is formed between ultra-thin orthogonal word and bit lines of high conductivity material whose thickness is less than 100 nm. Lines of this thickness produce switching magnetic fields at the cell free layer that are enhanced by a factor of approximately two for a given current. The fabrication of a cell with such thin lines is actually simplified as a result of the thinner depositions because the fabrication process eliminates the necessity of removing material by CMP during patterning and polishing, thereby producing uniform spacing between the lines and the cell free layer.

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San Jose, CA, United States of America

Pokang Wang