Semiconductor device manufacturing: process – Having magnetic or ferroelectric component
Reexamination Certificate
2003-07-29
2004-11-16
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Having magnetic or ferroelectric component
Reexamination Certificate
active
06818458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to magnetic storage systems and more particularly to methods for forming low resistance magnetic tunnel junction devices.
2. Description of Related Art
Magnetic recording is a key segment of the information-processing industry. While the basic principles are one hundred years old for early tape devices, and over forty years old for magnetic hard disk drives, an influx of technical innovations continues to extend the storage capacity and performance of magnetic recording products. For hard disk drives, the areal density or density of written data bits on the magnetic medium has increased by a factor of more than two million since the first disk drive was used for data storage. Areal density continues to grow due to improvements in magnet recording heads, media, drive electronics, and mechanics.
A magnetoresistive (MR) sensor changes resistance in the presence of a magnetic field. Recorded data can be read from a recorded magnetic medium, such as a magnetic disk, because the magnetic field from the recorded magnetic medium causes a change in the direction of magnetization in the read element, which causes a corresponding change in the sensor resistance.
Recently, magnetic tunnel junction sensor devices have been proposed for a variety of applications, including read heads for magnetic disks as well as magnetoresistive random access memory. A magnetic tunnel junction (MTJ) is a type or magnetoresistive device made of at least two magnetic film layers separated by an insulating barrier. The insulating barrier is thin enough to allow electrons to quantum mechanically tunnel through the barrier. Resistance of an MTJ is directly related to the tunneling probability that depends on the relative orientation of the magnetization vectors of the magnetic layers. Because the orientation of the magnetization vector depends on the applied field, the resistance of a MTJ device varies in the presence of a magnetic field.
The MTJ device resistance limits the data access rate of a sensor incorporating an MTJ element. It is desirable to produce an MTJ sensor with low resistance to increase the data access rate for magnetic read heads and MRAM elements.
SUMMARY OF THE INVENTION
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses methods, devices and systems relating to a magnetic tunnel junction device.
In accordance with one embodiment of the invention a method for forming a magnetic tunnel junction structure includes forming a first magnetic layer and a second magnetic layer. At least one of the first and the second magnetic layers includes diffusion components selected to adjust one or more properties of the magnetic tunnel junction device. The method further includes forming a barrier layer between the first and the second magnetic layers. The barrier layer includes migrated diffusion components from the at least one magnetic layer, wherein the diffusion components adjust the one or more properties.
In accordance with another embodiment of the invention a method of forming a magnetic tunnel junction device includes forming a magnetic tunnel junction active region. The magnetic tunnel junction active region includes a first magnetic layer and a second magnetic layer. At least one of the first and the second magnetic layers includes diffusion components selected to adjust one or more properties of the magnetic tunnel junction device. The magnetic tunnel junction active region further includes a barrier layer between the first and the second magnetic layers. The active region is annealed to enhance migration of the diffusion components from the first magnetic layer to the barrier layer. The migrated diffusion components adjust the one or more properties of the magnetic tunnel junction device.
In accordance with yet another embodiment of the invention, a method for sensing a magnetic field comprises forming a magnetic tunnel junction device. The magnetic tunnel junction device includes a first magnetic layer and a second magnetic layer. At least one of the first and the second magnetic layers includes diffusion components selected to adjust one or more properties of the tunnel junction device. The magnetic tunnel junction device further includes a barrier layer between the first and the second magnetic layers. The method magnetic tunnel junction device is annealed to enhance migration of the diffusion components from the first magnetic layer to the barrier layer. The migrated diffusion components adjust the one or more properties of the magnetic tunnel junction device. The method of sensing a magnetic field further includes driving the magnetic tunnel junction device using an electrical signal and detecting an electrical resistance based on magnetic orientations of the first and the second magnetic layers.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.
REFERENCES:
patent: 5416353 (1995-05-01), Kamiguchi et al.
patent: 6737691 (2004-05-01), Asao
patent: 2002/0061421 (2002-05-01), Dieny
patent: 2003/0086313 (2003-05-01), Asao
patent: 2003/0170985 (2003-09-01), Hwang et al.
Crawford & Maunu PLLC
Hitachi Global Storage Technologies - Netherlands B.V.
Le Thao P.
Nelms David
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