Western Digital (fremont), Inc.

Headway Technologies, Incorporated

Applied Spintronics, Inc.

Read Rite Corporation

Magic Technologies, Inc.

Applied Spintronics Technology, Inc.

Stmicroelectronics S.r.l.

Applied Spintadnics, Inc.

Xizeng Shi

Po-Kang Wang

Kyusik Sin

Hugh Craig Hiner

Hua-Ching Tong

Yimin Guo

Yingjian Chen

Tai Min

Matthew R Gibbons

Hsu Kai Yang

Francis H Liu

Qiuqun Qi

Chyu-Jiuh Torng

Yugang Wang

Pokang Wang

William D Jensen

Shin Funada

Hsu Kai (Karl) Yang

Kochan Ju

Lei Wang

Jei-Wei Chang

Kroum Stanimirov Stoev

Xiaozhong Dang

Benjamin P Chen

Ming Zhao

Hai Jiang

Bruce Yee Yang

Cherng-Chyi Han

Yimin Hsu

Paolo Giuseppe Cappelletti

Roberto Bez

Robert Earl Rottmayer

Giulio Casagrande

Po Kang Wang

David Tsang

David Hu

Zi-Wen Dong

Son Le

Charles C Cheng

Chester Xiaowen Chien

Lijun Tong

Subrata Dey

Arthur Hungshin Tao

Joyce Thompson

Yin Rong

Kristian M Bjelland

Qiuqun (Kevin) Qi

A method of forming a sensor array comprising a series connection of parallel GMR sensor stripes that provides a sensitive mechanism for detecting the presence of magnetized particles bonded to biological molecules that are affixed to a substrate. The adverse effect of hysteresis on the maintenance of a stable bias point for the magnetic moment of the sensor free layer is eliminated by a combination of biasing the sensor along its longitudinal direction rather than the usual transverse direction and by using the overcoat stress and magnetostriction of magnetic layers to create a compensatory transverse magnetic anisotropy. By making the spaces between the stripes narrower than the dimension of the magnetized particle and by making the width of the stripes equal to the dimension of the particle, the sensitivity of the sensor array is enhanced.

GMR biosensor with enhanced sensitivity

A sensor array comprising a series connection of parallel GMR sensor stripes provides a sensitive mechanism for detecting the presence of magnetized particles bonded to biological molecules that are affixed to a substrate. The adverse effect of hysteresis on the maintenance of a stable bias point for the magnetic moment of the sensor free layer is eliminated by a combination of biasing the sensor along its longitudinal direction rather than the usual transverse direction and by using the overcoat stress and magnetostriction of magnetic layers to create a compensatory transverse magnetic anisotropy. By making the spaces between the stripes narrower than the dimension of the magnetized particle and by making the width of the stripes equal to the dimension of the particle, the sensitivity of the sensor array is enhanced.

A GMR sensor stripe provides a sensitive mechanism for detecting the presence of magnetized particles bonded to biological molecules that are affixed to a substrate. The adverse effect of hysteresis on the maintenance of a stable bias point for the magnetic moment of the sensor stripe free layer is eliminated by a combination of biasing the sensor stripe along its longitudinal direction rather than the usual transverse direction and by using the overcoat stress and magnetostriction of magnetic layers to create a compensatory transverse magnetic anisotropy. By connecting the stripes in an array and making the spaces between the stripes narrower than the dimension of the magnetized particle and by making the width of the stripes equal to the dimension of the particle, the sensitivity of the sensor array is enhanced.

GMR sensor stripe for a biosensor with enhanced sensitivity

A magnetic sensor for identifying small superparamagnetic particles bonded to a substrate contains a regular orthogonal array of MTJ cells formed beneath that substrate. A magnetic field imposed on the particle, perpendicular to the substrate, induces a magnetic field that has a component within the MTJ cells that is along the plane of the MTJ free layer. If that free layer has a low switching threshold, the induced field of the particle will create resistance changes in a group of MTJ cells that lie beneath it. These resistance changes will be distributed in a characteristic formation or signature that will indicate the presence of the particle. If the particle's field is insufficient to produce the free layer switching, then a biasing field can be added in the direction of the hard axis and the combination of this field and the induced field allows the presence of the particle to be determined.

Devices using addressable magnetic tunnel junction array to detect magnetic particles

A method and system for programming and reading a magnetic memory is disclosed. The magnetic memory includes a plurality of selectable word line segments and a plurality of magnetic storage cells corresponding to each word line segment. The method and system include reading the magnetic storage cells corresponding to a word line segment to determine a state of each magnetic storage cell. The method and system also include writing data to a portion of the magnetic cells corresponding to the word line segment after the reading. The method and system also include rewriting the state to each of a remaining portion of the magnetic storage cells corresponding to the word line segments at substantially the same time as the portion of the magnetic cells are written.

Method and system for optimizing the number of word line segments in a segmented MRAM array

An MRAM reference cell sub-array provides a mid-point reference current to sense amplifiers. The MRAM reference cell sub-array has MRAM cells arranged in rows and columns. Bit lines are associated with each column of the sub-array. A coupling connects the bit lines of pairs of the columns together at a location proximally to the sense amplifiers. The MRAM cells of a first of the pair of columns are programmed to a first magneto-resistive state and the MRAM cells of a second of the pair of columns are programmed to a second magneto-resistive state. When one row of data MRAM cells is selected for reading, a row of paired MRAM reference cells are placed in parallel to generate the mid-point reference current for sensing. The MRAM reference sub-array may be programmed electrically or aided by a magnetic field. A method for verifying programming of the MRAM reference sub-array is discussed.

Reference cell scheme for MRAM

An MRAM array has a plurality of MRAM devices that are arranged in rows and columns with segmented word lines. A magnetic biasing field is coupled to each of the MRAM devices. The MRAM devices are programmed by providing a bidirectional bit line current to a selected bit line of the plurality of bit lines and a word line current pulse to one word line segment of one row of word line segments by discharging coupled word line segments. The field biasing device may be permanent magnetic layers or write biasing lines in proximity to the fixed magnetic layer of each of the MRAM and has a magnetic orientation equivalent to the magnetic orientation of a word line segment magnetic field generated by the word line current pulse.

Programming scheme for segmented word line MRAM array

A method of using an MTJ MRAM cell element having two magnetization states of greater and lesser stability. During switching, the free layer is first placed in the less stable state by a word line current, so that a small bit line current can switch its magnetization direction. After switching, the state reverts to its more stable form as a result of magnetostatic interaction with a SAL (soft adjacent layer), which is a layer of soft magnetic material formed on an adjacent current carrying line, which prevents it from being accidentally rewritten when it is not actually selected and also provides stability against thermal agitation.

Magnetic random access memory array with free layer locking mechanism and method of its use

An MTJ MRAM cell is formed between or below an intersection of ultra-thin orthogonal word and bit lines of high conductivity material whose thickness is less than 100 nm. Lines of this thickness produce switching magnetic fields at the cell free layer that are enhanced by a factor of approximately two for a given current. The fabrication of a cell with such thin lines is actually simplified as a result of the thinner depositions because the fabrication process eliminates the necessity of removing material by CMP during patterning and polishing, thereby producing uniform spacing between the lines and the cell free layer.

Magnetic random access memory array with thin conduction electrical read and write lines

An MTJ MRAM cell is formed between ultra-thin orthogonal word and bit lines of high conductivity material whose thickness is less than 100 nm. Lines of this thickness produce switching magnetic fields at the cell free layer that are enhanced by a factor of approximately two for a given current. Because the lines require thinner depositions, there is no necessity of removing material by CMP during patterning and polishing. Therefore, there is a uniform spacing between the lines and the cell free layer.

A configurable MRAM device is achieved. The device comprises a memory array of magnetic memory cells. A first part of the array comprises the memory cells that can be accessed for reading and writing during normal operation. A second part of the array comprises the memory cells that can be read only during a power up initialization. The second part of the array is used to store configuration data for altering the physical operation of the memory array. Programmable current sources and timing delays use the stored configuration data to optimize device performance. A redundant section of memory cells is activated by the configuration data.

Configurable MRAM and method of configuration

An MTJ MRAM cell element, whose free layer has a shape induced magnetic anisotropy, is formed between orthogonal word and bit lines. The bit line is a composite line which includes a high conductivity current carrying layer and a soft adjacent magnetic layer (SAL). During operation, the soft magnetic layer concentrates the magnetic field of the current and, due to its proximity to the free layer, it magnetically couples with the free layer to produce two magnetization states of greater and lesser stability. During switching, the layer is first placed in the less stable state by a word line current, so that a small bit line current can switch its magnetization direction. After switching, the state reverts to its more stable form as a result of magnetostatic interaction with the SAL, which prevents it from being accidentally rewritten when it is not actually selected and also provides stability against thermal agitation.

Magnetic random access memory array with free layer locking mechanism

In an MRAM array based on MTJs, the size of segmented word line select transistors and their associated connections become a significant overhead, especially when the operating point is chosen deep along the hard axis of the asteroid curve. This problem has been overcome by placing the big segmented word line select transistors under the MTJ array and reducing the overall MRAM cell array down to a level comparable to a simple Cross Point MRAM array.

Highly efficient segmented word line MRAM array

Growing community of inventors

Fremont, CA, United States of America

Xizeng Shi