International Business Machines Corporation

Headway Technologies, Incorporated

Hitachi Global Storage Technologies Netherlands B.v.

Joseph Francis Smyth

Glen A Garfunkel

Hardayal Singh Gill

Moris Musa Dovek

Edward Hinpong Lee

Samuel Wonder Yuan

Yoshitaka Sasaki

Yuchen Zhou

Daniele Mauri

Tsann Lin

Bruce Alvin Gurney

Edward Hin Pong Lee

Hiroyuki Itoh

Kenichi Takano

Douglas Johnson Werner

Virgil S Speriosu

Min Li

David John Seagle

Lijie Guan

Richard Hsiao

Neil Leslie Robertson

Ching Hwa Tsang

Yan Wu

Hugo Alberto Emilio Santini

Howard Gordon Zolla

Jih-Shiuan Luo

John David Westwood

Michael Paul Salo

Ciaran Avram Fox

David Hu

Samuel Wei-san Yuan

Timothy J Moran

Dong-Hong Li

Yaw-Shing Tang

Chin-Yu Yeh

Wenchein Hsiao

Peter John Melz

A read head with two read sensors enables reading of a magnetically recorded medium of increased areal densities such as would be provided by two-dimensional magnetic recording. The two sensors, which may be formed in separate depositions, are arranged vertically relative to each other as top and bottom sensors, with a downtrack displacement between them that is less than 900 A and a crosstrack displacement that is less than 600 A. Their separate free layers are connected by four or three conducting leads and require no junctions for their connections. In one embodiment each sensor has separate top and bottom shields and leads. In another embodiment, there is a common shield and lead between the two sensors, but a separate top shield/lead for the top sensor and bottom shield/lead for the bottom sensor.

Two sensor reader for hard disk drive (HDD)

A method is disclosed for forming a magnetic shield in which all domain patterns and orientations are stable and which are consistently repeated each time said shield is exposed to an initialization field. The shield is given a shape which ensures that all closure domains can align themselves at a reduced angle relative to the initialization direction while still being roughly antiparallel to one another. Most, though not all, of these shapes are variations on trapezoids.

Shield design for magnetic recording head

A magnetic shield in which all domain patterns and orientations are stable and which are consistently repeated each time the shield is exposed to an initialization field, is disclosed. This is achieved by giving it a suitable shape which ensures that all closure domains can align themselves at a reduced angle relative to the initialization direction while still being roughly antiparallel to each other. Most, though not all, of these shapes are variations on trapezoids.

A pole layer has an end face located in a medium facing surface, allows a magnetic flux corresponding to a magnetic field generated by a coil to pass therethrough, and generates a write magnetic field for writing data on a recording medium by using a perpendicular magnetic recording system. A shield incorporates: a first layer having an end face located in a region of the medium facing surface forward of the end face of the pole layer along the direction of travel of the recording medium; a second layer disposed in a region sandwiching the pole layer with the first layer; a first coupling portion coupling the first layer to the second layer without touching the pole layer; and a second coupling portion coupling the pole layer to the second layer and located farther from the medium facing surface than the first coupling portion.

Magnetic head for perpendicular magnetic recording and method of manufacturing same

A magnetic head comprises a pole layer and first and second coils located in regions sandwiching the pole layer. Each of the two coils is flat-whorl-shaped. The first coil incorporates an inner connecting portion and an outer connecting portion opposite to the inner connecting portion. The second coil also incorporates an inner connecting portion and an outer connecting portion opposite to the inner connecting portion. The inner connecting portion of the first coil is electrically connected to the inner connecting portion of the second coil. The outer connecting portion of the first coil is electrically connected to the outer connecting portion of the second coil, too. In such a manner the two coils are electrically connected to each other in parallel.

Magnetic head for perpendicular magnetic recording

An automated production process for the screening of the read-width (RW) and/or the stripe-height (SH) for every magnetoresistive (MR) read sensor element in a wafer substrate. The method of this invention uses the RW and/or SH values found with optical examination by electron microscopy of several of the MR sensor elements to estimate two substrate coefficients that relates the optical RW and SH measurements to heating-delta measurements, &dgr;&equals;(RH&minus;RC)/RC, where RH is the sensor resistance when hot and RC is the sensor resistance when cold, both of which can be measured using automated equipment. These relationships are sufficiently similar among all MR sensor elements manufactured on a single wafer substrate during a single manufacturing procedure that, when the hot resistance RH is measured at a constant applied voltage, the heating-delta, may be used with a first substrate coefficient to estimate the read-width RW of each MR sensor element for quality-control purposes during manufacture. When the hot resistance RH is measured at a constant applied current, the heating-delta may be used with a second substrate coefficient to estimate the stripe-height SH of each MR sensor element for quality-control purposes during manufacture.

Method for the rapid measurement of magnetoresistive read head dimensions

An low profile inductive write head is provided to improve track definition and head efficiency and to reduce overcoat and pole tip protrusion and cracking caused by thermal expansion. A first insulation layer of an insulation stack enclosing the coil layer is formed of an non-magnetic inorganic insulator material such as aluminum oxide, silicon dioxide or titanium dioxide having a thickness of in the range of 0.2-0.3 microns. The thinner first insulation layer results in a significantly reduced slope of the insulation stack which decreases reflective notching during processing of the second pole tip to improve track definition. Improved thermal conduction properties of the inorganic insulator material improves heat sinking of the write coil reducing overcoat and pole tip protrusion and cracking at the pole tip/write gap layer interface.

Enhanced low profile magnet write head

To protect the MR read head element from ESD damage during wafer level manufacturing, a lead from the MR element is electrically connected to one or both of the read head element shields during manufacturing. In a preferred embodiment of the present invention, the electrical connection is fabricated in the kerf area between adjacent magnetic heads as they are fabricated upon a wafer substrate. Thereafter, when the magnetic heads are separated by saw cutting through the kerf areas, the electrical connections are thereby removed, such that the MR element electrical leads and the shields are electrically isolated. In an alternative embodiment, one or more of the shields, as well as the MR element leads can also be electrically connected to the substrate upon which the magnetic head is fabricated. In further alternative embodiments, the electrical connection between one or more of the shields and the MR element electrical lead can be fabricated within the magnetic head area, rather than in the kerf area, and a suitable resistance is fabricated into the interconnecting circuit. In this embodiment, the electrical interconnection between the MR element electrical lead and one or more of the shields has a pre-designed electrical resistance and it remains in the magnetic head following fabrication.

ESD protection during GMR head fabrication

A method for forming a merged thin film magnetic head having a first shield layer and a combined second shield and bottom pole piece layer arranged in a sandwich supporting a read sensor therebetween at the pole tip region. The combined second shield and bottom pole piece layer are magnetically coupled with the first shield layer at the pole tip end of the yoke region adjacent the read sensor, and overlaying and magnetically coupled with the first shield layer at the back gap region. A patterned opening is provided in the combined second shield and bottom pole piece layer at the yoke region thereof to expose the first shield layer and form a flat planarization surface thereon. A plurality of stacked thin film coil layers are provided in the patterned opening, and a top pole piece layer overlies the thin film coil at the yoke region, overlies the bottom pole piece at the pole tip region providing a pole tip and gap thereat, and overlies the bottom pole piece at the back gap region. The patterned opening which exposes the first shield layer allows the provision of a multi-layer coil while maintaining a low profile of the head.

Method for forming low profile multi-layer coil merged thin film magnetic head

A fully-pinned, flux-closed spin valve (SV) magnetoresistive sensor having a reference (pinned) layer with magnetization fixed by a first antiferromagnetic (AFM,) layer, and a keeper layer with magnetization fixed by a second antiferromagnetic (AFM,) layer. The magnetization of the keeper layer is saturated and fixed in an antiparallel orientation to the pinned layer magnetization by an exchange interaction with the AFM2 layer. The magnetic moments of the pinned layer and the keeper layer are approximately matched to form a flux-closed magnetic configuration wherein demagnetizing fields in the pinned layer are largely canceled and magnetostatic interaction with the free layer is reduced. Saturation of the keeper layer magnetization by exchange coupling with the AFM,layer eliminates or reduces magnetization canting at the edges of the keeper layer which can result in signal field shunting through the keeper layer. AFM,and AFM,layers may be formed of the same antiferromagnetic material, such as NiO, or alternatively may be formed of different antiferromagnetic materials, such as Ni&mdash;Mn and NiO, respectively.

Fully-pinned, flux-closed spin valve

A high moment bilayer first pole piece layer of a write head has high magnetic stability for promoting read signal symmetry of a read sensor of a read head. The bilayer first pole piece layer has a first layer of nickel iron and a second layer of iron nitride. The iron nitride has a high magnetic moment for conducting more flux per volume than the nickel iron first layer. In a first aspect of the invention, the nickel iron first layer is highly stabilized by providing it with a negative magnetostriction so that a stress induced anisotropy (H.sub.K) supports an intrinsic uniaxial anisotropy (H.sub.K) of the nickel iron first layer. The iron nitride second layer is formed directly on the nickel iron first layer so that by magnetic coupling the iron nitride second layer has significantly improved magnetic stability. In a second aspect of the invention the iron nitride second layer is provided with a positive magnetostriction which still further increases the magnetic stability of the bilayer first pole piece layer. In a preferred embodiment a net magnetostriction is zero or near zero. Each aspect of the invention improves the asymmetry sigma of the read head.

High moment bilayer first pole piece layer of a write head with high

An SV sensor having a reference (pinned) layer formed of a first high uniaxial anisotropy ferromagnetic material, such as Co--Fe, and a keeper layer formed of a second high uniaxial anisotropy ferromagnetic material, such as Ni--Fe--Nb. Lapping induced stress in the Co--Fe layer having high positive magnetostriction generates a stress-induced uniaxial anisotropy field in the reference layer resulting in enhanced reference layer magnetization. This uniaxial anisotropy field is capable by itself of maintaining a substantial transverse reference layer saturation even at elevated temperatures. Lapping induced stress in the Ni--Fe--Nb layer having high positive magnetostriction generates a stress-induced uniaxial anisotropy field in the keeper layer providing more uniform magnetization and therefore better flux cancellation. The high electrical resistivity of the Ni--Fe--Nb keeper layer has the further benefit of reducing sense current shunting by the keeper layer.

Spin valves with high uniaxial anisotropy reference and keeper layers

Disclosed is a merged thin film magnetic head having a first shield layer and a combined second shield and bottom pole piece layer arranged in a sandwich supporting a read sensor therebetween at the pole tip region. The combined second shield and bottom pole piece layer are magnetically coupled with the first shield layer at the pole tip end of the yoke region adjacent the read sensor, and overlaying and magnetically coupled with the first shield layer at the back gap region. A patterned opening is provided in the combined second shield and bottom pole piece layer at the yoke region thereof to expose the first shield layer and form a flat planarization surface thereon. A plurality of stacked thin film coil layers are provided in the patterned opening, and a top pole piece layer overlies the thin film coil at the yoke region, overlies the bottom pole piece at the pole tip region providing a pole tip and gap thereat, and overlies the bottom pole piece at the back gap region. The patterned opening which exposes the first shield layer allows the provision of a multi-layer coil while maintaining a low profile of the head.

Low profile multi-layer coil merged thin film magnetic head

An orthogonal spin valve read head is provided wherein a spin valve sensor is asymmetrically located between first and second shield layers so that image currents in the first and second shield layers produce a resultant image field which partially or completely counterbalances a stiffening field from antiferromagnetic, pinned and spacer layers in the MR sensor when sense current is conducted therethrough. Accordingly, the spin valve sensor may be located a greater distance from the second shield layer by providing a mid-gap layer between the spin valve sensor and a second gap layer. In one example, the total thickness of the mid-gap and second gap layer is four times as thick as the first gap layer which results in the image fields from the first and second shield layers completely counterbalancing the field from the antiferromagnetic, pinned and spacer layers due to the sense current.

Orthogonal spin valve sensor with reduced net field

A monitoring apparatus is provided for determining permeabilities of a vacuum-deposited second pole piece of a magnetic head at the wafer level by providing wafer-mounted monitors which have layers formed by the same masking and deposition steps employed in making the magnetic heads so that the layers of the monitors are replicated layers, except for a shaping layer on top of a replicated second pole piece of some of the monitors. Each monitor is a transformer wherein each of a primary winding and a secondary winding comprises essentially a replicated magnetic head. The first and second pole pieces of the replicated magnetic heads are joined so as to magnetically couple the primary and secondary windings that constitute the transformer. The replicated shaping layer is omitted in part to expose a portion of one of the replicated second pole pieces of a monitor, such as the front slope, the back slope or the yoke portion of the replicated second pole piece which corresponds to the front slope, the back slope or yoke respectively of the magnetic head. When a current is conducted through the replicated coils of the monitor a voltage reading can be taken to indicate the permeability of the exposed portion of the replicated second pole piece of the monitor.

Growing community of inventors

Los Altos, CA, United States of America

Joseph Francis Smyth