Headway Technologies, Incorporated

International Business Machines Corporation

Applied Spintronics, Inc.

Magic Technologies, Inc.

Mao-Min Chen

Cherng-Chyi Han

Cheng Tzong Horng

Kochan Ju

Po-Kang Wang

Ru-Ying Tong

Min Li

Chyu-Jiuh Torng

Jei-Wei Chang

Liubo Hong

Chen-Jung Chien

Pokang Wang

Neil Leslie Robertson

Ching Hwa Tsang

Simon H Liao

Yimin Guo

Moris Musa Dovek

Mohamad Towfik Krounbi

Hui-Chuan Wang

Cherng Chyi Han

Chyu Jiuh Torng

Lei Zhang

Fenglin Liu

Po Kang Wang

Laurie Jane Lauchlan

Rodney E Lee

Kenneth Ting-Yuan Kung

Ru-Yin Tong

Kunliang Zhang

Bernard Dieny

Li-Yan Zhu

Yun-Fei Li

Hugo Alberto Santini

Robert Otto Schwenker

You Feng Zheng

Henry C Chang

Chien-Li Lin

Charles H Lin

Shou-Chen Kao

Rong-Fu Xiao

Chun Liu

Jun Yuan

Gene Michael Sandler

Jen-Wei C Koo

Mustafa Pinarbasi

Robert Fontana

Tai Min

Yue Liu

Rongfu Xiao

Jyh-Shuey Jerry Lo

Jiun-Ting Lee

Danning Yang

Denny D Tang

Xiaomin Liu

James Hsi-Tang Lee

Mary Kathryn Gutberlet

Rod Lee

Daniel Gerard Abels

Jei Wei Chang

Cheng-Teh Wu

Timothy J Gallagher

Jyh-Shiliey Jerry Lo

Jeu-Wei C Koo

Ku-Ying Tong

Po-Kang Wan

Wang: Po-Kang

Jacqueline K Latimer

An MRAM structure is disclosed in which the bottom electrode has an amorphous TaN capping layer to consistently provide smooth and dense growth for AFM, pinned, tunnel barrier, and free layers in an overlying MTJ. Unlike a conventional Ta capping layer, TaN is oxidation resistant and has high resistivity to avoid shunting of a sense current caused by redeposition of the capping layer on the sidewalls of the tunnel barrier layer. Alternatively, the &#x3b1;-TaN layer is the seed layer in the MTJ. Furthermore, the seed layer may be a composite layer comprised of a NiCr, NiFe, or NiFeCr layer on the &#x3b1;-TaN layer. An &#x3b1;-TaN capping layer or seed layer can also be used in a TMR read head. An MTJ formed on an &#x3b1;-TaN capping layer has a high MR ratio, high Vb, and a RA similar to results obtained from MTJs based on an optimized Ta capping layer.

Underlayer for high performance magnetic tunneling junction MRAM

Methods are presented for fabricating an MTJ element having a uniform vertical distance between its free layer and a bit line and, in addition, having a protective spacer layer formed abutting the lateral sides of the MTJ element to eliminate leakage currents between MTJ layers and the bit line. Each method forms a dielectric spacer layer on the lateral sides of the MTJ element and, depending on the method, includes an additional layer that protects the spacer layer during etching processes used to form a Cu damascene bit line. At various stages in the process, a dielectric layer is also formed to act as a CMP stop layer so that the capping layer on the MTJ element is not thinned by the CMP process that planarizes the surrounding insulation. Subsequent to planarization, the stop layer is removed by an anisotropic etch of such precision that the MTJ element capping layer is not reduced in thickness and serves to maintain uniform vertical distance between the bit line and the MTJ free layer.

Spacer structure in MRAM cell and method of its fabrication

An MRAM structure is disclosed in which the bottom electrode has an amorphous TaN capping layer to consistently provide smooth and dense growth for AFM, pinned, tunnel barrier, and free layers in an overlying MTJ. Unlike a conventional Ta capping layer, TaN is oxidation resistant and has high resistivity to avoid shunting of a sense current caused by redeposition of the capping layer on the sidewalls of the tunnel barrier layer. Alternatively, the &#x3b1;-TaN layer is the seed layer in the MTJ. Furthermore, the seed layer may be a composite layer of NiCr, NiFe, or NiFeCr layer on the oc-TaN layer. An &#x3b1;-TaN capping layer or seed layer can also be used in a TMR read head. An MTJ formed on an &#x3b1;-TaN capping layer has a high MR ratio, high Vb, and a RA similar to results obtained from MTJs based on an optimized Ta capping layer.

Methods are presented for fabricating an MTJ element having a precisely controlled spacing between its free layer and a bit line and, in addition, having a protective spacer layer formed abutting the lateral sides of the MTJ element to eliminate leakage currents between MTJ layers and the bit line. Each method forms a dielectric spacer layer on the lateral sides of the MTJ element and, depending on the method, includes an additional layer that protects the spacer layer during etching processes used to form a Cu damascene bit line. At various stages in the process, a dielectric layer is also formed to act as a CMP stop layer so that the capping layer on the MTJ element is not thinned by the CMP process that planarizes the surrounding insulation. Subsequent to planarization, the stop layer is removed by an anisotropic etch of such precision that the MTJ element capping layer is not thinned and serves to maintain an exact spacing between the bit line and the MTJ free layer.

Aggressive (i.e. tight tolerance) stitching offers several advantages for magnetic write heads but at the cost of some losses during pole trimming. This problem has been overcome by replacing the alumina filler layer, that is used to protect the stitched pole during trimming, with a layer of electro-plated material. Because of the superior step coverage associated with the plating method of deposition, pole trimming can then proceed without the introduction of stresses to the stitched pole while it is being trimmed.

Abs through aggressive stitching

A manufacturing process is provided where aggressive (i.e. tight tolerance) stitching offers several advantages for magnetic write heads but at the cost of some losses during pole trimming. This problem has been overcome by replacing the alumina filler layer, that is used to protect the stitched pole during trimming, with a layer of electroplated material. Because of the superior step coverage associated with the plating method of deposition, pole trimming can then proceed without the introduction of stresses to the stitched pole while it is being trimmed.

Process to form an ABS through aggressive stitching

Although it is known that exchange bias can be utilized in abutted junctions for longitudinal stabilization, a relatively large moment is needed to pin down the sensor edges effectively. Due to the inverse dependence of the exchange bias on the magnetic layer thickness, a large exchange bias has been difficult to achieve by the prior art. This problem has been solved by introducing a structure in which the magnetic moment of the bias layer has been approximately doubled by pinning it from both above and below through exchange with antiferromagnetic layers. Additionally, since the antiferromagnetic layer is in direct abutted contact with the free layer, it acts directly to help stabilize the sensor edge, which is an advantage over the traditional magnetostatic pinning that had been used.

Exchange bias structure for abutted junction GMR sensor

A hard bias structure for biasing a free layer in a MR element within a magnetic read head is comprised of a soft magnetic underlayer such as NiFe and a hard bias layer comprised of CoCrPtor CoCrPtthat are rigidly exchange coupled to ensure a well aligned longitudinal biasing direction with minimal dispersions. The hard bias structure is formed on a BCC seed layer such as CrTi to improve lattice matching. The hard bias structure may be laminated in which each of the underlayers and hard bias layers has a thickness that is adjusted to optimize the total H, Mt, and S values. The present invention encompasses CIP and CPP spin values, MTJ devices, and multi-layer sensors. A larger process window for fabricating the hard bias structure is realized and lower asymmetry output and NBLW (normalized base line wandering) reject rates during a read operation are achieved.

Composite hard bias design with a soft magnetic underlayer for sensor applications

A trimmed upper pole piece for a magnetic write head, said pole piece having a tapered profile that is widest at its trailing edge. Such a pole piece is capable of writing narrow tracks with sharply and well defined patterns and minimal overwriting of adjacent tracks. The necessary taper is produced by using NiCr, NiFeCr, Rh or Ru as write gap filling materials which have an etch rate which is substantially equal to the etch rate of the other layers forming the pole piece and are highly corrosion resistant. As a result, the write gap does not protrude to mask the effects of the ion-beam etch used to form the taper.

Magnetic write head having a wider trailing edge pole structure

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 trimmed upper pole piece for a magnetic write head is presented, said pole piece having a uniform width above and below a write gap layer and said pole piece being formed on a pedestal of uniform width projecting from a planar surface of a magnetic shield layer. Prior art methods of trimming pole pieces to a final width using ion-beam etches produce pole pieces with thickness differentials due to the etch resistant nature of the typical alumina write-gap filling material. The present pole piece uses NiCr, NiFeCr or Ru as write gap filling materials because they have an etch rate which is substantially equal to the etch rate of the other layers forming the pole piece and allow a uniform trimming to occur.

Self-aligned trimmed pole

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

Growing community of inventors

San Jose, CA, United States of America

Mao-Min Chen