Patents by Inventor Kochan Ju
Kochan Ju has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 9337415Abstract: A magnetic tunnel junction (MTJ) for use in a magnetoresistive random access memory (MRAM) has a CoFeB alloy free layer located between the MgO tunnel barrier layer and an upper MgO capping layer, and a CoFeB alloy enhancement layer between the MgO capping layer and a Ta cap. The CoFeB alloy free layer has high Fe content to induce perpendicular magnetic anisotropy (PMA) at the interfaces with the MgO layers. To avoid creating unnecessary PMA in the enhancement layer due to its interface with the MgO capping layer, the enhancement layer has low Fe content. After all of the layers have been deposited on the substrate, the structure is annealed to crystallize the MgO. The CoFeB alloy enhancement layer inhibits diffusion of Ta from the Ta cap layer into the MgO capping layer and creates good crystallinity of the MgO by providing CoFeB at the MgO interface.Type: GrantFiled: March 20, 2015Date of Patent: May 10, 2016Assignee: HGST Netherlands B.V.Inventors: Sangmun Oh, Zheng Gao, Kochan Ju
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Patent number: 9202482Abstract: A magnetic sensor having a novel pinning structure resulting in a greatly reduced gap spacing. The sensor has a magnetic free layer structure that extends to a first stripe height and a magnetic pinned layer structure that extends to a second stripe height that is longer than the first stripe high. A layer of anti-ferromagnetic material is formed over the pinned layer structure in the region beyond the first stripe height location. In this way, the antiferromagnetic layer is between the pinned layer and the second or upper shield and does not contribute to gap spacing.Type: GrantFiled: August 27, 2013Date of Patent: December 1, 2015Assignee: HGST Netherlands B.V.Inventors: Quang Le, Simon H. Liao, Guangli Liu, Kochan Ju, Youfeng Zheng
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Patent number: 9001473Abstract: The embodiments disclosed generally relate to a read head in a magnetic recording head. The read head utilizes a sensor structure having: a pinned magnetic structure recessed from a media facing surface; and a reader gap structure. The reader gap structure has a spacer layer recessed from the media facing surface and disposed on top of the pinned magnetic structure, a recessed first free layer partially recessed from the media facing surface and disposed on top of the barrier layer, a second free layer extending to the media facing surface an disposed on top of the barrier layer, and a cap layer extending to the media facing surface disposed atop the second free layer. The pinned magnetic structure, the spacer, and the first free layer have a common face which is on an angle relative to the media facing surface.Type: GrantFiled: March 21, 2014Date of Patent: April 7, 2015Assignee: HGST Netherlands B.V.Inventors: Zheng Gao, James Mac Freitag, Kuok San Ho, Ching Hwa Tsang, Kochan Ju
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Publication number: 20150062751Abstract: A magnetic sensor having a novel pinning structure resulting in a greatly reduced gap spacing. The sensor has a magnetic free layer structure that extends to a first stripe height and a magnetic pinned layer structure that extends to a second stripe height that is longer than the first stripe high. A layer of anti-ferromagnetic material is formed over the pinned layer structure in the region beyond the first stripe height location. In this way, the antiferromagnetic layer is between the pinned layer and the second or upper shield and does not contribute to gap spacing.Type: ApplicationFiled: August 27, 2013Publication date: March 5, 2015Applicant: HGST Netherlands B.V.Inventors: Quang Le, Simon H. Liao, Guangli Liu, Kochan Ju, Youfeng Zheng
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Patent number: 8941954Abstract: A magnetic read head that has improved pinned layer stability while also maintaining excellent free layer stability. The free layer has sides that define a trackwidth of the sensor and a back edge that defines a functional stripe height of the sensor. However, the pinned layer can extend significantly beyond both the width of the free layer and the back edge (e.g. stripe height) of the free layer. The sensor also has a soft magnetic bias structure that compensates for the reduced volume presented by the side extension of the pinned layer. The soft magnetic bias structure can be magnetically coupled with the trailing magnetic shield, either parallel coupled or anti-parallel coupled. In addition, all or a portion of the soft magnetic bias structure can be exchange coupled to a layer of anti-ferromagnetic material in order to improve the robustness of the soft magnetic bias structure.Type: GrantFiled: December 19, 2012Date of Patent: January 27, 2015Assignee: HGST Netherlands B.V.Inventors: Quang Le, Simon H. Liao, Guangli Liu, Kochan Ju, Youfeng Zheng
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Patent number: 8842395Abstract: A magnetic read sensor having an extended pinned layer structure and also having an extended free layer structure. The extended pinned layer structure and extended free layer structure both extend beyond the strip height of the free layer of the sensor to provide improved pinning strength as well as improved free layer biasing reliability and bias field strength.Type: GrantFiled: December 19, 2012Date of Patent: September 23, 2014Assignee: HGST Netherlands B.V.Inventors: Kochan Ju, Quang Le, Simon H. Liao, Guangli Liu
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Patent number: 8780507Abstract: A transducer according to one embodiment comprises a first ferromagnetic layer; a second ferromagnetic layer; and an electrically conductive layer positioned between the ferromagnetic layers; wherein a length of the first ferromagnetic layer in a first direction parallel to a plane of deposition thereof is greater than a length of the electrically conductive layer in the first direction such that a first end of the first ferromagnetic layer extends beyond an end of the electrically conductive layer in the first direction, wherein an electrical current enters or exits the end of the first ferromagnetic layer that extends beyond the end of the electrically conductive layer in the first direction. Additional transducer structures, and systems implementing such transducers, are also disclosed.Type: GrantFiled: December 28, 2007Date of Patent: July 15, 2014Assignee: HGST Netherlands B.V.Inventors: Ying Hong, Kochan Ju, Ching Hwa Tsang
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Publication number: 20140168822Abstract: A magnetic read head that has improved pinned layer stability while also maintaining excellent free layer stability. The free layer has sides that define a trackwidth of the sensor and a back edge that defines a functional stripe height of the sensor. However, the pinned layer can extend significantly beyond both the width of the free layer and the back edge (e.g. stripe height) of the free layer. The sensor also has a soft magnetic bias structure that compensates for the reduced volume presented by the side extension of the pinned layer. The soft magnetic bias structure can be magnetically coupled with the trailing magnetic shield, either parallel coupled or anti-parallel coupled. In addition, all or a portion of the soft magnetic bias structure can be exchange coupled to a layer of anti-ferromagnetic material in order to improve the robustness of the soft magnetic bias structure.Type: ApplicationFiled: December 19, 2012Publication date: June 19, 2014Applicant: HGST NETHERLANDS B.V.Inventors: Quang Le, Simon H. Liao, Guangli Liu, Kochan Ju, Youfeng Zheng
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Publication number: 20140168824Abstract: A magnetic read sensor having an extended pinned layer structure and also having an extended free layer structure. The extended pinned layer structure and extended free layer structure both extend beyond the strip height of the free layer of the sensor to provide improved pinning strength as well as improved free layer biasing reliability and bias field strength.Type: ApplicationFiled: December 19, 2012Publication date: June 19, 2014Applicant: HGST NETHERLANDS B.V.Inventors: Kochan Ju, Quang Le, Simon H. Liao, Guangli Liu
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Patent number: 8325450Abstract: A magnetic structure in one embodiment includes a tunnel barrier layer; a free layer; and a buffer layer between the tunnel barrier layer and the free layer, wherein a cross sectional area of the tunnel barrier layer in a direction parallel to a plane of deposition thereof is greater than a cross sectional area of the free layer in a direction parallel to a plane of deposition thereof, wherein a cross sectional area of the buffer layer in a direction parallel to a plane of deposition thereof is greater than a cross sectional area of the free layer in the direction parallel to the plane of deposition thereof. Additional systems and methods are also presented.Type: GrantFiled: December 10, 2008Date of Patent: December 4, 2012Assignee: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Ying Hong, Kochan Ju, Tsann Lin, Ching Hwa Tsang
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Publication number: 20120164757Abstract: The present invention provides a method for manufacturing a TMR sensor that reduces damage to a sensor stack during intermediate stages of the manufacturing process. In an embodiment of the invention, after formation of a sensor stack, a protective layer is deposited on the sensor stack that provides protection from materials that may be used in subsequent steps of the manufacturing process. The protective layer is subsequently converted to an insulating layer and the thickness of the insulating layer is extended to an appropriate thickness. In converting the protective layer to an insulating layer, the sensor stack is not directly exposed to materials that may damage it. For example, in an embodiment of the invention, Mg is used as the protective layer that is subsequently converted to MgO with the introduction of oxygen. Although direct contact of oxygen with the sensor stack may cause damage to the sensor stack, direct contact is avoided by the present invention.Type: ApplicationFiled: December 27, 2010Publication date: June 28, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Zheng Gao, Liubo Hong, Richard Hsiao, Kochan Ju, Stefan Maat
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Patent number: 7864490Abstract: The series resistance of a CPP GMR stack can be reduced by shaping it into a small upper, on a somewhat larger, lower part. Because of the sub-micron dimensions involved, good alignment between these is normally difficult to achieve. The present invention discloses a self-alignment process based on first laying down a mask that will determine the shape of the top part. Ion beam etching is then initiated, the ion beam being initially applied from one side only at an angle to the surface normal. During etching, all material on the near side of the mask gets etched but, on the far side, only material that is outside the mask's shadow gets removed so, depending on the beam's angle, the size of the lower part is controlled and the upper part is precisely centrally aligned above it.Type: GrantFiled: September 18, 2007Date of Patent: January 4, 2011Assignee: Headway Technologies, Inc.Inventors: Jeiwei Chang, Stuart Kao, Chao Peng Chen, Chunping Luo, Kochan Ju, Min Li
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Publication number: 20100142099Abstract: A magnetic structure in one embodiment includes a tunnel barrier layer; a free layer; and a buffer layer between the tunnel barrier layer and the free layer, wherein a cross sectional area of the tunnel barrier layer in a direction parallel to a plane of deposition thereof is greater than a cross sectional area of the free layer in a direction parallel to a plane of deposition thereof, wherein a cross sectional area of the buffer layer in a direction parallel to a plane of deposition thereof is greater than a cross sectional area of the free layer in the direction parallel to the plane of deposition thereof. Additional systems and methods are also presented.Type: ApplicationFiled: December 10, 2008Publication date: June 10, 2010Inventors: Ying Hong, Kochan Ju, Tsann Lin, Ching Hwa Tsang
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Patent number: 7675718Abstract: The problem of increased edge sensitivity associated with the reduction of the spacing between bias magnets in a CPP head has been solved by limiting the width of the bias cancellation layer and by adding an extra layer of insulation to ensure that current through the device flows only through its central area, thereby minimizing its edge reading sensitivity.Type: GrantFiled: October 27, 2006Date of Patent: March 9, 2010Assignee: Headway Technologies, Inc.Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
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Publication number: 20090168235Abstract: CPP read sensors and associated methods of fabrication are described that provide lateral spreading of a sense current along the length of an AFM layer of the read sensor. Winged regions (i.e., extended portions) are added to the layers of a CPP sensor stack to induce lateral spreading of the sense current in the AFM layer. Particularly, the pinned layer and the AFM layer have widths greater than the other layers of the sensor stack. Further, the pinned layer comprises multiple layers of materials, with a first layer of material closer to the AFM layer having a lower conductivity and/or a lower spin dependent scattering asymmetry than the second layer of material.Type: ApplicationFiled: December 27, 2007Publication date: July 2, 2009Inventors: Kochan Ju, Ching Hwa Tsang
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Publication number: 20090168263Abstract: A transducer according to one embodiment comprises a first ferromagnetic layer; a second ferromagnetic layer; and an electrically conductive layer positioned between the ferromagnetic layers; wherein a length of the first ferromagnetic layer in a first direction parallel to a plane of deposition thereof is greater than a length of the electrically conductive layer in the first direction such that a first end of the first ferromagnetic layer extends beyond an end of the electrically conductive layer in the first direction, wherein an electrical current enters or exits the end of the first ferromagnetic layer that extends beyond the end of the electrically conductive layer in the first direction. Additional transducer structures, and systems implementing such transducers, are also disclosed.Type: ApplicationFiled: December 28, 2007Publication date: July 2, 2009Inventors: Ying Hong, Kochan Ju, Ching Hwa Tsang
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Patent number: 7506430Abstract: The problem of increased edge sensitivity associated with the reduction of the spacing between bias magnets in a CPP head has been solved by limiting the width of the bias cancellation layer and by adding an extra layer of insulation to ensure that current through the device flows only through its central area, thereby minimizing its edge reading sensitivity.Type: GrantFiled: October 27, 2006Date of Patent: March 24, 2009Assignee: Headway Technologies, Inc.Inventors: Jei-Wei Chang, Koichi Terunuma, Youfeng Zheng, Kochan Ju
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Patent number: 7477491Abstract: It has been found that the insertion of a copper laminate within CoFe, or a CoFe/NiFe composite, leads to higher values of CPP GMR and DRA. However, this type of structure exhibits very negative magnetostriction, in the range of high ?10?6 to ?10?5. This problem has been overcome by giving the copper laminates an oxygen exposure treatment When this is done, the free layer is found to have a very low positive magnetostriction constant. Additionally, the value of the magnetostriction constant can be adjusted by varying the thickness of the free layer and/or the position and number of the oxygen treated copper laminates.Type: GrantFiled: November 7, 2005Date of Patent: January 13, 2009Assignee: Headway Technologies, Inc.Inventors: Min Li, Kunliang Zhang, Masashi Sano, Koichi Terunuma, Simon Liao, Kochan Ju
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Patent number: 7453720Abstract: A “toggling” type of magnetic random access memory (MRAM) has memory stacks arranged in the X-Y plane on the MRAM substrate with each memory stack having a plurality of toggle memory cells stacked along the Z axis. Each stack is located at an intersection region between the two orthogonal write lines. The cells are stacked in pairs, with the cells in each pair having their easy axes of magnetization aligned substantially parallel to one another and nonparallel with the X and Y axes. The cells in each pair have their free layers magnetically biased in opposite directions. Because the free layer of each cell in a pair is biased in a direction opposite to the bias direction of the free layer of the other cell, one cell in a pair can be toggle written without toggle writing the other cell in the pair. The bias fields on the free layers reduces the required switching field for each cell, which results in less write current and a lower-power toggling MRAM.Type: GrantFiled: May 26, 2005Date of Patent: November 18, 2008Assignee: Maglabs, Inc.Inventors: Kochan Ju, Jei-Wei Chang
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Patent number: 7420780Abstract: Single write poles tend to large shape anisotropy which results in a very large remnant field when not actually writing. This has now been eliminated by giving the write pole the form of a three layer laminate in which two ferromagnetic layers are separated by a non-magnetic or antiferromagnetic coupling layer. Strong magnetostatic coupling between the outer layers causes their magnetization directions to automatically be antiparallel to one another, unless overcome by the more powerful write field, leaving the structure with a low net magnetic moment. The thickness of the middle layer must be carefully controlled.Type: GrantFiled: May 16, 2006Date of Patent: September 2, 2008Assignee: Headay Technologies, Inc.Inventors: Kochan Ju, Lijie Guan, Jeiwei Chang, Min Li, Ben Hu