Patents Assigned to Headway Technologies, Inc.
  • Spin transfer MRAM device with reduced coefficient of MTJ resistance variation
    Patent number: 9865321
    Abstract: We describe the manufacturing process for and structure of a CPP MTJ MRAM unit cell that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The cell is formed of a vertically or horizontally series connected sequence of N sub-cells, each sub-cell being an identical MTJ element. A statistical population of such multiple sub-cell unit cells has a variation of resistance that is less by a factor of N?1/2 than that of a population of single sub-cells. As a result, such unit cells have an improved read margin while not requiring an increase in the critical switching current.
    Type: Grant
    Filed: July 22, 2016
    Date of Patent: January 9, 2018
    Assignee: Headway Technologies, Inc.
    Inventor: Yimin Guo
  • Plasmon generator with metallic waveguide blocker for TAMR
    Patent number: 9852752
    Abstract: A TAMR (thermal assisted magnetic recording) write head has a metal blocker formed against a distal end of a waveguide. The waveguide focuses optical radiation on an adjacent plasmon generator where it excites plasmon modes that heat the recording medium. Although the plasmon generator typically heats the recording medium using the plasmon near field to supply the required Joule heating, an unblocked waveguide would also send optical radiation to the medium and surrounding structures producing unwanted heating and device unreliability. The role of the blocker is to block the unwanted optical radiation and, thereby, to limit the heating to that supplied by the plasmon near field.
    Type: Grant
    Filed: August 12, 2016
    Date of Patent: December 26, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Tsutomu Chou, Kouji Shimazawa, Tobias Maletzky, Weihao Xu, Shinji Hara, Yoshihiro Tsuchiya, Yiming Wang, Cherng-Chyi Han, Xuhui Jin
  • Magnetic tunnel junction with low defect rate after high temperature anneal for magnetic device applications
    Patent number: 9842988
    Abstract: A magnetic tunnel junction is disclosed wherein the reference layer and free layer each comprise one layer having a boron content from 25 to 50 atomic %, and an adjoining second layer with a boron content from 1 to 20 atomic %. One of the first and second layers in each of the free layer and reference layer contacts the tunnel barrier. Each boron containing layer has a thickness of 1 to 10 Angstroms and may include one or more B layers and one or more Co, Fe, CoFe, or CoFeB layers. As a result, migration of non-magnetic metals along crystalline boundaries to the tunnel barrier is prevented, and the MTJ has a low defect count of around 10 ppm while maintaining an acceptable TMR ratio following annealing to temperatures of about 400° C. The boron containing layers are selected from CoB, FeB, CoFeB and alloys thereof including CoFeNiB.
    Type: Grant
    Filed: July 20, 2015
    Date of Patent: December 12, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Huanlong Liu, Yuan-Jen Lee, Jian Zhu, Guenole Jan, Po-Kang Wang
  • Magnetic head for perpendicular magnetic recording with a coil including a first winding portion of one turn and a second winding portion of less than one turn
    Patent number: 9824702
    Abstract: A magnetic head includes a coil, a main pole and a return path section. The return path section is located on the trailing side relative to the main pole so that a space is defined between the main pole and itself. The coil includes a first winding portion and a second winding portion connected in series. The first winding portion extends to pass through the aforementioned space, and extends once around the entire perimeter of the main pole as viewed from the medium facing surface. The second winding portion does not pass through the aforementioned space, and surrounds only a part of the entire perimeter of the main pole as viewed from the medium facing surface.
    Type: Grant
    Filed: June 8, 2017
    Date of Patent: November 21, 2017
    Assignee: HEADWAY TECHNOLOGIES, INC.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Kazuki Sato, Yukinori Ikegawa, Shigeki Tanemura, Kenichi Takano
  • Thermally-assisted magnetic recording head including a main pole and a plasmon generator
    Patent number: 9812156
    Abstract: A thermally-assisted magnetic recording head includes a main pole and a plasmon generator. The main pole has a front end face located in the medium facing surface. The plasmon generator has a near-field light generating surface located in the medium facing surface. The front end face of the main pole includes a first end face portion and a second end face portion. The second end face portion is located farther from the near-field light generating surface than is the first end face portion, and is greater than the first end face portion in width in the track width direction. The first end face portion and the near-field light generating surface are equal in width.
    Type: Grant
    Filed: January 20, 2015
    Date of Patent: November 7, 2017
    Assignee: HEADWAY TECHNOLOGIES, INC.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Shigeki Tanemura, Hideo Mamiya, Hironori Araki, Seiichiro Tomita
  • Implementation of a one time programmable memory using a MRAM stack design
    Patent number: 9805816
    Abstract: An integrated circuit includes a magnetic OTP memory array formed of multiple magnetic OTP memory cells having an MTJ stack with a fixed magnetic layer, a tunnel barrier insulating layer, a free magnetic layer, and a second electrode. When a voltage is applied across the magnetic OTP memory cell, the resistance of the MTJ stack and the gating transistor form a voltage divider to apply a large voltage across the MTJ stack to breakdown the tunnel barrier to short the fixed layer to the free layer. The integrated circuit has multiple MRAM arrays configured such that each of the multiple MRAM arrays have performance and density criteria that match MOS transistor based memory including SRAM, DRAM, and flash memory. The integrated circuit may include a functional logic unit connected with the magnetic OTP memory arrays and the MRAM arrays for providing digital data storage.
    Type: Grant
    Filed: March 23, 2016
    Date of Patent: October 31, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Guenole Jan, Po-Kang Wang, Yuan-Jen Lee, Jian Zhu, Huanlong Liu
  • Method of manufacturing a magnetic film having high coercivity for use as a hot seed in a magnetic write head
    Patent number: 9805743
    Abstract: A method of forming a sub-structure, suitable for use as a hot seed in a perpendicular magnetic recording head, is described. A buffer layer of alumina with a thickness of 50-350 Angstroms is formed by atomic layer deposition as a write gap. Thereafter, one or more seed layers having a body-centered cubic (bcc) crystal structure may be deposited on the buffer layer. Finally, a magnetic film made of FeCo or FeNi with a coercivity of 60-110 Oe is deposited on the seed layer(s) by a physical vapor deposition (PVD) method at a rate of 0.48 to 3.6 Angstroms per second. The magnetic film is preferably annealed at 220° C. for 2 hours in a 250 Oe applied magnetic field.
    Type: Grant
    Filed: May 15, 2015
    Date of Patent: October 31, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Shengyuan Wang, Kunliang Zhang, Min Li
  • Copper plating method
    Patent number: 9797047
    Abstract: A method of removing copper oxide from copper surfaces is disclosed that comprises application of vapor generated by an ultrasonic wave nebulizer. The energized vapor droplets include water and a weak organic acid such as acetic acid, lactic acid, citric acid, uric acid, oxalic acid, or formic acid that have a vapor pressure proximate to that of water. The weak organic acid preferably has a pKa high enough to avoid Cu etching but is sufficiently acidic to remove copper oxide at a rate that is compatible with high throughput manufacturing. In one embodiment, weak acid/water vapor is applied to a substrate in a spin bowl and is followed by a deionized water rinse step in the same spin bowl. Improved wettability results in improved uniformity in subsequently plated copper films. Considerable cost savings is realized as a result of reduced chemical consumption and higher product yields.
    Type: Grant
    Filed: August 10, 2015
    Date of Patent: October 24, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Chao-Peng Chen, Jas Chudasama, Chien-Li Lin, David Wagner
  • Magnetic reader sensor with shield spacing improvement and better pin flop robustness
    Patent number: 9799357
    Abstract: A MR sensor is disclosed with an antiferromagnetic (AFM) layer recessed behind a bottom shield to reduce reader shield spacing and improve pin related noise. Above the AFM layer is an AP2/AFM coupling layer/AP1 stack that extends from an air bearing surface to the MR sensor backside. The AP2 layer is pinned by the AFM layer, and the AP1 layer serves as a reference layer to an overlying free layer during a read operation. The AP1 and AP2 layers have improved resistance to magnetization flipping because back portions thereof have a full cross-track width “w” between MR sensor sides thereby enabling greater pinning strength from the AFM layer. Front portions of the AP1/AP2 layers lie under the free layer and have a track width less than “w”. The bottom shield may have an anti-ferromagnetic coupling structure. A process flow is provided for fabricating the MR sensor.
    Type: Grant
    Filed: November 8, 2016
    Date of Patent: October 24, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Ruhang Ding, Yewhee Chye, Wenyu Chen, Kunliang Zhang, Min Li
  • Magnetic head for perpendicular magnetic recording including a coil having an inclined surface
    Patent number: 9792929
    Abstract: A magnetic head includes a medium facing surface, a coil, a main pole, a write shield, and a first and a second return path section. The first return path section is located on the leading side of the main pole. The coil includes a specific coil element passing through a space defined by main pole, a gap section, write shield and first return path section. The main pole has a bottom end including a first portion and a second portion, the second portion being farther from medium facing surface than is the first portion. The specific coil element has a rear end farthest from medium facing surface. The distance from medium facing surface to rear end of the specific coil element is smaller than or equal to the distance from the medium facing surface to the boundary between the first portion and the second portion.
    Type: Grant
    Filed: February 21, 2017
    Date of Patent: October 17, 2017
    Assignee: HEADWAY TECHNOLOGIES, INC.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Kazuki Sato, Yukinori Ikegawa, Shigeki Tanemura, Hironori Araki
  • Method of manufacturing a thin-film magnetic head including a coil and a magnetic path forming section
    Patent number: 9777387
    Abstract: A thin-film magnetic head includes a coil, a magnetic path forming section, and an insulating film. The magnetic path forming section includes first and second magnetic material portions. The coil includes first and second coil elements located between the first and second magnetic material portions. The insulating film includes an underlying portion located under the first and second coil elements. In a method of manufacturing the thin-film magnetic head, the insulating film is formed to cover the first and second magnetic material portions, and then a seed layer is formed selectively on the underlying portion of the insulating film. The coil is formed by plating using the seed layer.
    Type: Grant
    Filed: October 24, 2014
    Date of Patent: October 3, 2017
    Assignee: HEADWAY TECHNOLOGIES, INC.
    Inventors: Yukinori Ikegawa, Yoshitaka Sasaki, Hiroyuki Ito, Hironori Araki, Seiichiro Tomita, Hideo Mamiya
  • Multilayer structure for reducing film roughness in magnetic devices
    Patent number: 9780299
    Abstract: A seed layer stack with a smooth top surface having a peak to peak roughness of 0.5 nm is formed by sputter depositing an amorphous layer on a seed layer such as Mg where the seed layer has a resputtering rate 2 to 30× that of the amorphous layer. The uppermost seed layer is a template layer that is NiCr or NiFeCr. As a result, perpendicular magnetic anisotropy in an overlying magnetic layer that is a reference layer, free layer, or dipole layer is substantially maintained during high temperature processing up to 400° C. and is advantageous for magnetic tunnel junctions in embedded MRAMs, spintronic devices, or in read head sensors. The amorphous seed layer is SiN, TaN, or CoFeM where M is B or another element with a content that makes CoFeM amorphous as deposited. The seed layer stack may include a bottommost Ta or TaN buffer layer.
    Type: Grant
    Filed: November 23, 2015
    Date of Patent: October 3, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Jian Zhu, Guenole Jan, Yuan-Jen Lee, Huanlong Liu, Ru-Ying Tong, Po-Kang Wang
  • Magnetic head for perpendicular magnetic recording that includes a sensor for detecting contact with a recording medium
    Patent number: 9773514
    Abstract: A magnetic head for perpendicular magnetic recording includes a read head unit, a write head unit disposed forward of the read head unit along the direction of travel of a recording medium, a heater that generates heat for causing the medium facing surface to protrude in part, an expansion layer that makes part of the medium facing surface protrude, and a sensor that detects contact of the part of the medium facing surface with the recording medium. The write head unit includes a main pole, a write shield, and a return path section. The return path section includes a yoke layer located backward of the main pole along the direction of travel of the recording medium, a first coupling part that couples the yoke layer and the write shield to each other, and a second coupling part that is located away from the medium facing surface and couples the yoke layer and the main pole to each other.
    Type: Grant
    Filed: February 25, 2011
    Date of Patent: September 26, 2017
    Assignees: HEADWAY TECHNOLOGIES, INC., SAE MAGNETICS (H.K.) LTD.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Kazuki Sato, Atsushi Iijima
  • Thermally-assisted magnetic recording head including a main pole and a plasmon generator
    Patent number: 9761253
    Abstract: A main pole has a front end face including a first to a third end face portion. A plasmon generator has a near-field-light-generating surface. A surrounding layer has a first surrounding layer end face and a second surrounding layer end face. A gap film has a first gap film end face and a second gap film end face located on opposite sides of the near-field-light-generating surface in the track width direction. The first and second end face portions are interposed between the first and second surrounding layer end faces. The second end face portion is greater in width than the first end face portion. The third end face portion is greater in width than the second end face portion.
    Type: Grant
    Filed: September 30, 2016
    Date of Patent: September 12, 2017
    Assignee: HEADWAY TECHNOLOGIES, INC.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Hideo Mamiya, Shigeki Tanemura, Seiichiro Tomita, Hironori Araki
  • Side shielded magnetoresistive (MR) read head with perpendicular magnetic free layer
    Patent number: 9761254
    Abstract: A MR sensor is disclosed that has a free layer (FL) with perpendicular magnetic anisotropy (PMA), which eliminates the need for an adjacent hard bias structure to stabilize free layer magnetization, and minimizes shield-FL interactions. In a TMR embodiment, a seed layer, free layer, junction layer, reference layer, and pinning layer are sequentially formed on a bottom shield. After forming a sensor sidewall that stops in the seed layer or on the bottom shield, a conformal insulation layer is deposited. Thereafter, a top shield is formed on the insulation layer and includes side shields that are separated from the FL by a narrow read gap. The sensor is scalable to widths <50 nm when PMA is greater than the FL self-demag field. Effective bias field is rather insensitive to sensor aspect ratio, which makes tall stripe and narrow width sensors viable for high RA TMR configurations.
    Type: Grant
    Filed: November 29, 2016
    Date of Patent: September 12, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Yuchen Zhou, Kunliang Zhang, Zhi Gang Bai
  • Areal density improvement of perpendicular magnetic recording (PMR) write head by tuning magnetic flux loops
    Patent number: 9754612
    Abstract: A PMR writer is disclosed wherein magnetic flux return from a magnetic medium to a main pole is substantially greater through a trailing shield structure than through a leading shield and return path layer (RTP). Magnetic impedance is increased between the RTP and main pole in the leading return loop by modifying the size and shape of the back gap connection (BGC), by decreasing Bs in the RTP or reducing its thickness, or by removing one or more layers in the BGC and replacing with dielectric material or non-magnetic metal to form a dielectric gap between the RTP and main pole. As a result, area density control and bit error rate are improved over a conventional dual write shield (DWS) structure comprising two flux return pathways. Moreover, adjacent track erasure is maintained at a level similar to a DWS design.
    Type: Grant
    Filed: November 20, 2015
    Date of Patent: September 5, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Yaguang Wei, Yuhui Tang, Moris Dovek, Yue Liu
  • Plasmon generator including a heat sink layer interposed between two portions formed of different metal materials
    Patent number: 9754614
    Abstract: A plasmon generator includes: a first portion formed of a first metal material and including a front end face configured to generate near-field light; a second portion formed of a second metal material and located at a distance from the front end face; and a heat sink layer formed of a third metal material, located at a distance from the front end face and interposed between the first portion and the second portion. The second metal material is lower in Vickers hardness and higher in thermal conductivity than the first metal material. The third metal material has a thermal conductivity higher than that of each of the first and second metal materials, and has a Vickers hardness lower than that of the first metal material and higher than that of the second metal material.
    Type: Grant
    Filed: August 23, 2016
    Date of Patent: September 5, 2017
    Assignee: HEADWAY TECHNOLOGIES, INC.
    Inventors: Yoshitaka Sasaki, Hiroyuki Ito, Yukinori Ikegawa, Shigeki Tanemura, Hideo Mamiya, Seiichiro Tomita
  • Adaptive reference scheme for magnetic memory applications
    Patent number: 9747965
    Abstract: A circuit and method for adaptive trimming of the reference signal for sensing data during a read operation of magnetic memory cells to improve read margin for the magnetic memory cells. The circuit has a trim one-time programmable memory array programmed with offset trim data applied to magnetic memory array sense amplifiers. Sense amplifier trimming circuits receive and decode the trim data to determine offset trim signal magnitude to adjust the reference signal to improve the read margin. The method sets the offset trim level to each increment of the offset trim level. Data is written and read to the magnetic memory array, the number of errors in the array is accumulated for each setting of the offset trim level. The error levels are compared and the appropriate trim level is programmed to the trim memory cells such that a read margin of the sense amplifier is improved.
    Type: Grant
    Filed: December 28, 2015
    Date of Patent: August 29, 2017
    Assignee: Headway Technologies, Inc.
    Inventors: Guenole Jan, Po-Kang Wang, John De Brosse, Yuan-Jen Lee
  • THERMALLY-ASSISTED MAGNETIC RECORDING HEAD INCLUDING A MAIN POLE AND A PLASMON GENERATOR
    Publication number: 20170243607
    Abstract: A thermally-assisted magnetic recording head includes a main pole and a plasmon generator. The plasmon generator includes a first material portion and a second material portion formed of different materials. The first material portion is located away from the medium facing surface. The second material portion includes a near-field light generating surface. The main pole has a front end face including a first end face portion and a second end face portion. The near-field light generating surface, the first end face portion and the second end face portion are arranged in this order along the direction of travel of a recording medium.
    Type: Application
    Filed: February 23, 2016
    Publication date: August 24, 2017
    Applicant: HEADWAY TECHNOLOGIES, INC.
    Inventors: Yoshitaka SASAKI, Hiroyuki ITO, Shigeki TANEMURA, Hideo MAMIYA, Seiichiro TOMITA, Hironori ARAKI
  • Method of forming a non-uniform write gap perpendicular writer for shingle writing
    Patent number: 9741368
    Abstract: A method of forming a PMR writer is disclosed wherein at least one of a recessed center section in the write pole trailing edge and a center recessed trailing shield is used to improve the field gradient at track edge. In all embodiments, there is a non-uniform write gap formed between the trailing edge and the trailing shield. The recessed portion of the write pole trailing edge and/or center recess of the trailing shield has a thickness from 10 to 40 nm in a down-track direction and a width in a cross-track direction of 20 to 200 nm. The distance between the center recess and a corner of the trailing edge is from 20 to 80 nm. A sequence of steps is provided to fabricate the two embodiments of the present invention.
    Type: Grant
    Filed: September 23, 2013
    Date of Patent: August 22, 2017
    Assignee: Headway Technologies, Inc.
    Inventor: Lijie Guan