Ching Ju Tsang

US Patent:

6440639, Aug 27, 2002

Filed:

Sep 28, 2000

Appl. No.:

09/672187

Inventors:

Jordan A. Katine - San Jose CA
Ernst Kratschmer - Yorktown Heights NY
Michael J. Rooks - Briarcliff Manor NY
Ching H. Tsang - Sunnyvale CA
Raman Gobichettipalayam Viswanathan - Briarcliff Manor NY

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G03C 516

US Classification:

430313, 430314, 430323, 430324, 430329, 4302701

Abstract:

A high-aspect ratio resist profile is obtained using a development process wherein a mixture of an alcohol and water is used as the developer. The alcohol/water mixture is non-toxic, and does not cause excess swelling and cracking of the resist during the development process.

US Patent:

6631055, Oct 7, 2003

Filed:

Jun 8, 2001

Appl. No.:

09/877358

Inventors:

Jeffrey R. Childress - San Jose CA
Robert E. Fontana - San Jose CA
Kuok San Ho - Cupertino CA
Ching H. Tsang - Sunnyvale CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539

US Classification:

360321

Abstract:

A flux guided magnetic tunnel junction head includes a ferromagnetic pinned layer having an active region with a front edge recessed from a sensing surface, and a non-active region located between the sensing surface and the active region. The non-active region of the ferromagnetic pinned layer is rendered substantially non-conducting by chemically processing the ferromagnetic material of the ferromagnetic pinned layer in this region. The flux guided MTJ head also includes a ferromagnetic free layer having a front edge substantially coplanar with a sensing surface. The ferromagnetic free layer can function as a flux guide to direct magnetic flux from a recording medium to the tunnel junction. The location of the front edge of the ferromagnetic pinned layer prevents any shorting of the flux guided MTJ head occurring when the head is lapped at the sensing surface.

US Patent:

6671139, Dec 30, 2003

Filed:

Jan 31, 2002

Appl. No.:

10/066067

Inventors:

Kashmira J. Carey - San Jose CA
Jeffrey R. Childress - San Jose CA
Kuok San Ho - Cupertino CA
Ching Hwa Tsang - Sunnyvale CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 5127

US Classification:

36032412

Abstract:

A magnetization of a ferromagnetic free layer of a current-in-plane (CIP) sensor is stabilized using an in-stack longitudinal bias structure that includes a ferromagnetic bias layer and an anti-ferromagnetic bias layer. An electrically insulating layer separates the ferromagnetic free layer and the in-stack longitudinal bias structure, and thus the leads attached to the CIP sensor do not make direct electrical contact with the in-stack longitudinal bias structure. As a result, the sense current shunted by the in-stack longitudinal bias structure is prevented. Since a width along the off track direction of the in-stack longitudinal bias structure is greater than the track-width of the CIP sensor, the edge magnetostatic coupling filed acting on the ferromagnetic free layer from the track width edges of the in-stack longitudinal bias structure is reduced to approximately zero.

US Patent:

6680832, Jan 20, 2004

Filed:

May 11, 2001

Appl. No.:

09/853352

Inventors:

Kuok San Ho - Cupertino CA
Jordan A. Katine - San Jose CA
Jeffrey S. Lille - Sunnyvale CA
Ching H. Tsang - Sunnyvale CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539

US Classification:

3603242, 360319

Abstract:

A current-perpendicular-to-the-plane (CPP) magnetoresistive sensor or read head has a magnetic shield geometry that covers the side walls of the sensor structure to prevent side reading caused by magnetic flux entering from adjacent data tracks. The shield geometry includes a bottom shield with a substantially planar surface and a specially shaped top shield. The top shield has substantially vertical portions generally parallel to the side walls of the sensor structure, a horizontal top portion over the trackwidth region of the sensor, and horizontal side portions formed over the portions of the bottom shield on either side of the sensor structure. The insulating gap material that separates the bottom and top shields is in contact with the horizontal portions of the bottom shield and the side walls of the sensor structure.

US Patent:

6833976, Dec 21, 2004

Filed:

May 15, 2002

Appl. No.:

10/147565

Inventors:

Yimin Hsu - Sunnyvale CA
Ching Hwa Tsang - Sunnyvale CA

Assignee:

International Business Machine Corporation - Armonk NY

International Classification:

G11B 523

US Classification:

360119, 360120, 360121

Abstract:

A thin film inductive write head for magnetic recording has a write gap formed as a lamination of alternating layers of a nonmagnetic gap layer and a ferromagnetic spacer layer. There are N gap layers and N-1 spacer layers, with each pole tip of the write head being located adjacent to a gap layer. The spacer layers in the gap structure are formed of a ferromagnetic material with a high saturation moment density (B ) that is close to the B of the spacer material from which the pole tips are formed. Unlike the pole tips, the spacer layers are not part of a magnetic circuit and are magnetically isolated, i. e. , completely surrounded by nonmagnetic gap material. The effect of the spacer layers is to effectively divide the gap into a plurality of smaller gaps. The write head with the laminated gap creates a write bubble that is narrower in the off-track direction and wider in the in-track direction.

US Patent:

6847510, Jan 25, 2005

Filed:

Sep 27, 2002

Appl. No.:

10/256722

Inventors:

Jeffrey R. Childress - San Jose CA, US
Kuok San Ho - Cupertino CA, US
Ching Hwa Tsang - Sunnyvale CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands B.V. - Amsterdam

International Classification:

G11B 539
G11C 1116

US Classification:

3603242, 36032412, 365158, 365171

Abstract:

A magnetic tunnel junction (MTJ) device usable as a magnetic memory cell or magnetoresistive sensor, such as a MTJ read head for magnetic recording, has the free ferromagnetic layer located on the bottom of the device, the bottom free layer being formed on a special underlayer. The MTJ read head may be a flux-guided head that uses the free layer as a flux guide for directing magnetic flux from the magnetic media to the sensing region of the MTJ. The special underlayer for the growth of the free layer is an alloy comprising Mn, one of Pt, Ni, Ir and Os, and an additive X selected from Ta, Al, Ti, Cu, Cr and V. Without the additive, the underlayer alloy is antiferromagnetic. The additive is present in an amount sufficient to render the alloy to have no magnetic ordering, i. e. , it is neither antiferromagnetic nor ferromagnetic, but without substantially affecting the preferred crystalline texture and unit cell size so that the underlayer is well-suited as a growth-enhancing underlayer for the free layer.

US Patent:

6888705, May 3, 2005

Filed:

Jan 18, 2002

Appl. No.:

10/054352

Inventors:

Kuok San Ho - Cupertino CA, US
Tao Pan - San Jose CA, US
Ching Hwa Tsang - Sunnyvale CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands B.V. - Amsterdam

International Classification:

G11B005/39

US Classification:

36032412, 3603242, 360321

Abstract:

Several embodiments of a sense current perpendicular to the planes of the sensor (CPP) and flux guide type of read head has a gap between first and second shield layers at an air bearing surface (ABS) where the flux guide is located which is less than a gap between the first and second shield layers at a recessed location where the sensor is located. This reduced gap increases the linear bit density capability of the read head. A longitudinal bias stack (LBS) is located in the sensor stack. Several unique methods of construction are described for forming the magnetic head assemblies.

US Patent:

6975485, Dec 13, 2005

Filed:

Jul 13, 2004

Appl. No.:

10/890658

Inventors:

Yimin Hsu - Sunnyvale CA, US
Ching Hwa Tsang - Sunnyvale CA, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B005/127

US Classification:

360119, 360121

Abstract:

A thin film inductive write head for magnetic recording has a write gap formed as a lamination of alternating layers of a nonmagnetic gap layer and a ferromagnetic spacer layer. There are N gap layers and N−1 spacer layers, with each pole tip of the write head being located adjacent to a gap layer. The spacer layers in the gap structure are formed of a ferromagnetic material with a high saturation moment density (B) that is close to the Bof the spacer material from which the pole tips are formed. Unlike the pole tips, the spacer layers are not part of a magnetic circuit and are magnetically isolated, i. e. , completely surrounded by nonmagnetic gap material. The effect of the spacer layers is to effectively divide the gap into a plurality of smaller gaps. The write head with the laminated gap creates a write bubble that is narrower in the off-track direction and wider in the in-track direction.