Gang S Xiao

US Patent:

6452240, Sep 17, 2002

Filed:

Oct 30, 2000

Appl. No.:

09/699651

Inventors:

Snorri T. Ingvarsson - White Plains NY
Roger H. Koch - Amawalk NY
Stuart S. Parkin - San Jose′ CA
Gang Xiao - Barrington RI

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H01L 2982

US Classification:

257421, 257422, 257295, 257426, 257427

Abstract:

In order to dampen magnetization changes in magnetic devices, such as tunnel junctions (MTJ) used in high speed Magnetic Random Access Memory (MRAM), a transition metal selected from the 4d transition metals and 5d transition metals is alloyed into the magnetic layer to be dampened. In a preferred form, a magnetic permalloy layer is alloyed with osmium (Os) in an atomic concentration of between 4% and 15% of the alloy.

US Patent:

6657431, Dec 2, 2003

Filed:

Jun 6, 2001

Appl. No.:

09/875436

Inventors:

Gang Xiao - Barrington RI

Assignee:

Brown University Research Foundation - Providence RI

International Classification:

G01N 2782

US Classification:

324244, 324210, 324252, 324750

Abstract:

A scanning magnetic microscope includes a specimen stage for holding a specimen to be examined; a sensor for sensing a magnetic field generated by the specimen, the sensor including one of a magnetic tunneling junction (MTJ) sensor, a spin valve sensor, or an extraordinary Hall effect sensor; translation apparatus for translating the sensor relative to a surface of said specimen; and a data processor, having an input coupled to an output of said sensor, for constructing an image of said magnetic field. In another embodiment a read/write head from a hard disk drive is shown to make a suitable magnetic sensor. The scanning magnetic microscope can be used for examining the current flow in integrated circuits and related phenomenon, such as electromigration, as well as magnetic data storage media and biomagnetic systems, to mention a few suitable applications.

US Patent:

6756237, Jun 29, 2004

Filed:

Mar 25, 2002

Appl. No.:

10/105831

Inventors:

Gang Xiao - Barrington RI
Xiaoyong Liu - Providence RI

Assignee:

Brown University Research Foundation - Providence RI

International Classification:

H01L 2100

US Classification:

438 3, 438238

Abstract:

Magnetic tunneling junction devices (MTJ) useful for sensing and memory applications and characterized by reduced resistance, magnetic noise, increased sensitivity, and increased magnetoresistance are disclosed herein. A method for fabrication of said MTJ is also disclosed wherein a series of materials are layered upon a substrate under controlled conditions, patterned and subjected to a period of annealing for simultaneously optimizing a plurality of performance parameters.

US Patent:

6930479, Aug 16, 2005

Filed:

Mar 7, 2003

Appl. No.:

10/493841

Inventors:

Gang Xiao - Barrington RI, US
Benaiah D. Schrag - Providence RI, US

Assignee:

Brown University Research Foundation - Providence RI

International Classification:

G01N027/00

US Classification:

324262, 324244

Abstract:

A scanning magnetic microscope (SMM) () includes a current source () for imposing an excitation current to a conductor-under-test (CUT) () and, if applicable, a reference current to a proximally located reference conductor (). During accelerated testing, the SMM () corrects thermal drift of the CUT () via the reference conductor (). A sensor () may be cooled by a heat sink () such as a pump () directing an airstream or a coldfinger (). The sensor may switch from a contact to a non-contact mode of scanning the CUT (). The SMM () and methods are useful for measuring electromigration in a CUT () as it occurs, for assembling the images into time lapsed representations such as a shape of the CUT (), for measuring electromigration as a function of a cross sectional area of a wire under a dielectric material (DM) (), for determining electrical parameters of the CUT (), and for optimizing a thickness of a DM () over a CUT (). The SMM () and methods are further useful for measuring morphological changes in a CUT () due to other stressing conditions, such as temperature, excitation current, physical stress(es), hostile environment, aging, semiconductor “burn-in”, or irradiation.

US Patent:

7145330, Dec 5, 2006

Filed:

Aug 14, 2003

Appl. No.:

10/493831

Inventors:

Gang Xiao - Barrington RI, US

Assignee:

Brown University Research Foundation - Providence RI

International Classification:

G01R 33/02

US Classification:

324244, 324247, 250306

Abstract:

A scanning magnetic microscope SMM () includes a sensor () for sensing a magnetic field generated by a specimen (), the sensor including one of a MTJ, a GMR, or an EHE sensor; translation apparatus (A–C, ) for translating the sensor relative to a surface of sad specimen; and a data processor (), having an input coupled to an output of said sensor, for constructing an image of said magnetic field. The sensor preferably includes one to three sensing units each defining a sensing axis for sensing a component of a magnetic field from a specimen, the sensing units disposed such that the sensing axes are orthogonal to one another. Pluralities of such sensors can be disposed in two or three dimensional arrays. The SMM can be used for examining the current flow in ICs, electromigration, magnetic data storage media, biomagnetic systems and magnetic ink used to print currency.

US Patent:

7192491, Mar 20, 2007

Filed:

Jul 15, 2002

Appl. No.:

10/195178

Inventors:

Snorri T. Ingvarsson - White Plains NY, US
Roger H. Koch - Amawalk NY, US
Stuart S. Parkin - San Jose CA, US
Gang Xiao - Barrington RI, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H01F 1/00
H01F 1/147

US Classification:

148100, 148306, 148310, 148311, 148312, 148313, 148315

Abstract:

In order to dampen magnetization changes in magnetic devices, such as magnetic tunnel junctions (MTJ) used in high speed Magnetic Random Access Memory (MRAM), a transition metal selected from the transition metals and transition metals is alloyed into the magnetic layer to be dampened. In a preferred form, a magnetic permalloy layer is alloyed with osmium (Os) in an atomic concentration of between 4% and 15% of the alloy.

US Patent:

20040164840, Aug 26, 2004

Filed:

Feb 21, 2003

Appl. No.:

10/371321

Inventors:

Gang Xiao - Barrington RI, US

Assignee:

Brown University Research Foundation

International Classification:

B32B009/00

US Classification:

338/03200H, 428/692000

Abstract:

An EHE magnetic sensor has an alloy of the form R[MN], M being Fe, Co, Ni, or magnetic alloys that contain Fe, Co or Ni. N is from the fifth or sixth period of the periodic table. If present, R is a rare earth element. In one embodiment, the alloy exhibits a Temperature Coefficient 0.003 Kin the room temperature region. Various geometric shapes of sensors are presented including one and two-dimensional arrays of sensors for measuring spatial magnetic fields. Vias () defined by a substrate () onto which an alloy layer () is disposed are filled with a conductive material in certain embodiments of arrays. Methods are disclosed for making a sensor, for designing a sensor at a thickness, for determining maximum acceptable current through a sensor, for reducing Joule heating of a sensor, and for making an array of sensors.

US Patent:

20040196681, Oct 7, 2004

Filed:

Apr 14, 2004

Appl. No.:

10/824959

Inventors:

Gang Xiao - Barrington RI, US
Xiaoyong Liu - Providence RI, US

International Classification:

G11C011/22

US Classification:

365/145000

Abstract:

Magnetic tunneling junction devices (MTJ) useful for sensing and memory applications and characterized by reduced resistance, magnetic noise, increased sensitivity, and increased magnetoresistance are disclosed herein. A method for fabrication of said MTJ is also disclosed wherein a series of materials are layered upon a substrate under controlled conditions, patterned and subjected to a period of annealing for simultaneously optimizing a plurality of performance parameters.