Patents by Inventor Cheng T. Horng

Cheng T. Horng 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).

  • Structure/method to form bottom spin valves for ultra-high density
    Patent number: 7325295
    Abstract: Two embodiments of a GMR sensor of the bottom spin valve (BSV) spin filter spin valve (SFSV) type are provided together with methods for their fabrication. In each embodiment the sensor includes an in-situ naturally oxidized specularly reflecting layer (NOL) which is a more uniform and dense layer than such layers formed by high temperature annealing or reactive-ion etching. In one embodiment, the sensor has an ultra thin composite free layer and a high-conductance layer (HCL), providing high output and low coercivity. In a second embodiment, along with the same NOL, the sensor has a laminated free layer which includes a non-magnetic conductive layer, which also provides high output and low coercivity. The sensors are capable of reading densities exceeding 60 Gb/in2.
    Type: Grant
    Filed: March 27, 2006
    Date of Patent: February 5, 2008
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Novel capping layer for a magnetic tunnel junction device to enhance dR/R and a method of making the same
    Publication number: 20080023740
    Abstract: An MTJ in an MRAM array or TMR read head is disclosed in which a low magnetization capping layer is a composite having a NiFeHf inner layer formed on a NiFe or CoFeB/NiFe free layer, a Ta middle layer, and a Ru outer layer on the Ta layer. For example, a low magnetization NiFeHf layer is achieved by co-sputtering NiFe and Hf targets with a forward power of 400 W and 200 W, respectively. A higher Hf content increases the oxygen gettering power of the NiFeHf layer and the thickness is modified to change dR/R, RA, and magnetostriction values. A so-called dead layer between the free layer and capping layer is restored by incorporating a NiFeHf layer on the free layer to improve lattice matching. The Fe content in the NiFe target used to make the NiFeHf layer is preferably the same as in the NiFe free layer.
    Type: Application
    Filed: July 31, 2006
    Publication date: January 31, 2008
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Free layer design for CPP GMR enhancement
    Patent number: 7323215
    Abstract: By using a composite free layer of Fe25% Co/NiFe, an improved CPP GMR device has been created. The resulting structure yields a higher CPP GMR ratio than prior art devices, while maintaining free layer softness and acceptable magnetostriction. A process for manufacturing the device is also described.
    Type: Grant
    Filed: May 14, 2004
    Date of Patent: January 29, 2008
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Cheng T. Horng, Ru-Ying Tong
  • CPP spin valve with ultra-thin CoFe(50%) laminations
    Patent number: 7288281
    Abstract: Fe rich CoFe can be used in AP1 to enhance CPP GMR. However, this is found to degrade the electro-migration performance of the device. This problem has been solved by using an AP1 that is a laminate of several CoFe(25%) layers, separated from one another by copper layers. Ultra-thin layers of iron-rich CoFe are then inserted at all the copper-CoFe interfaces.
    Type: Grant
    Filed: September 2, 2004
    Date of Patent: October 30, 2007
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Kunliang Zhang, Cheng T. Horng, Chyu Jiuh Torng, Yu-Hsia Chen, Ru-Ying Tong
  • Method for fabricating a low resistance TMR read head
    Patent number: 7264974
    Abstract: A method is provided for forming a magnetoresistive read head with an MTJ configuration having an ultra-thin tunneling barrier layer with low resistance and high breakdown strength. The barrier layer is formed by natural oxidation of an ultra-thin (two atomic layers) Al or Hf—Al layer deposited on an electrode whose surface has first been treated to form an oxygen surfactant layer, the oxygen within the surfactant layer being adsorbed within the ultra-thin layer to produce a uniform and stable Al2O3 stoichiometry (or HfO stoichiometry) in the tunneling barrier layer.
    Type: Grant
    Filed: January 30, 2004
    Date of Patent: September 4, 2007
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • FeTa nano-oxide layer as a capping layer for enhancement of giant magnetoresistance in bottom spin valve structures
    Patent number: 7262941
    Abstract: An NiCr seed layer based bottom spin valve sensor element having a synthetic antiferromagnet pinned (SyAP) layer and a capping layer comprising either a single specularly reflecting nano-oxide layer (NOL) or a bi-layer comprising a non-metallic layer and a specularly reflecting nano-oxide layer. As a result of their structure and the method of their fabrication, these elements have higher GMR ratios and lower resistances than elements of the prior art.
    Type: Grant
    Filed: May 28, 2004
    Date of Patent: August 28, 2007
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Simon H. Liao, Masashi Sano, Kiyoshi Noguchi, Kochan Ju, Cheng T. Horng
  • Process and structure to fabricate CPP spin valve heads for ultra-high recording density
    Patent number: 7256971
    Abstract: A CPP-GMR spin value sensor structure with an improved MR ratio and increased resistance is disclosed. All layers except certain pinned layers, copper spacers, and a Ta capping layer are oxygen doped by adding a partial O2 pressure to the Ar sputtering gas during deposition. Oxygen doped CoFe free and pinned layers are made slightly thicker to offset a small decrease in magnetic moment caused by the oxygen dopant. Incorporating oxygen in the MnPt AFM layer enhances the exchange bias strength. An insertion layer such as a nano-oxide layer is included in one or more of the free, pinned, and spacer layers to increase interfacial scattering. The thickness of all layers except the copper spacer may be increased to enhance bulk scattering. A CPP-GMR single or dual spin valve of the present invention has up to a threefold increase in resistance and a 2 to 3% increase in MR ratio.
    Type: Grant
    Filed: March 9, 2004
    Date of Patent: August 14, 2007
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Buffer (seed) layer in a high-performance magnetic tunneling junction MRAM
    Patent number: 7238979
    Abstract: An MTJ (magnetic tunneling junction) device particularly suitable for use as an MRAM (magnetic random access memory) or a tunneling magnetoresistive (TMR) read sensor, is formed on a seed layer which allows the tunneling barrier layer to be ultra-thin, smooth, and to have a high breakdown voltage. The seed layer is a layer of NiCr which is formed on a sputter-etched layer of Ta. The tunneling barrier layer for the MRAM is formed from a thin layer of Al which is radically oxidized (ROX), in-situ, to form the layer with characteristics described above. The tunneling barrier layer for the read sensor formed from a thin layer of Al or a HfAl bilayer which is naturally oxidized (NOX), in-situ, to form the barrier layer. The resulting device has generally improved performance characteristics in terms of GMR ratio and junction resistance.
    Type: Grant
    Filed: September 26, 2005
    Date of Patent: July 3, 2007
    Assignees: Headway Technologies, Inc., Applied Spintronics, Inc.
    Inventors: Cheng T. Horng, Liubo Hong, Ru-Ying Tong, Yu-Hsia Chen
  • Method of fabricating novel seed layers for fabricating spin valve heads
    Patent number: 7234228
    Abstract: A method for forming a bottom spin valve sensor element with a novel seed layer and synthetic antiferromagnetic pinned layer. The novel seed layer comprises an approximately 30 angstrom thick layer of NiCr whose atomic percent of Cr is 31%. On this seed layer there can be formed either a single bottom spin valve read sensor or a symmetric dual spin valve read sensor having synthetic antiferromagnetic pinned layers. An extremely thin (approximately 80 angstroms) MnPt pinning layer can be formed directly on the seed layer and extremely thin pinned and free layers can then subsequently be formed so that the sensors can be used to read recorded media with densities exceeding 60 Gb/in2. Moreover, the high pinning field and optimum magnetostriction produces an extremely robust sensor.
    Type: Grant
    Filed: December 3, 2002
    Date of Patent: June 26, 2007
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Hui-Chuan Wang, Ru-Ying Tong, Chyu-Jiuh Trong
  • Structure/method to fabricate a high-performance magnetic tunneling junction MRAM
    Patent number: 7217577
    Abstract: An MTJ (magnetic tunneling junction) MRAM (magnetic random access memory) cell is formed on a conducting lead and magnetic keeper layer that is capped by a sputter-etched Ta layer. The Ta capping layer has a smooth surface as a result of the sputter-etching and that smooth surface promotes the subsequent formation of a lower electrode (pinning/pinned layer) with smooth, flat layers and a radical oxidized (ROX) Al tunneling barrier layer which is ultra-thin, smooth, and to has a high breakdown voltage. A seed layer of NiCr is formed on the sputter-etched capping layer of Ta. The resulting device has generally improved performance characteristics in terms of its switching characteristics, GMR ratio and junction resistance.
    Type: Grant
    Filed: September 18, 2006
    Date of Patent: May 15, 2007
    Assignees: Headway Technologies, Inc., Applied Spintronics, Inc.
    Inventors: Cheng T. Horng, Mao-Min Chen, Liubo Hong, Ru-Ying Tong
  • Structure and method to fabricate high performance MTJ devices for MRAM applications
    Patent number: 7211447
    Abstract: A method of forming a high performance MTJ in an MRAM array is disclosed. A Ta/Ru capping layer in a bottom conductor is sputter etched to remove the Ru layer and form an amorphous Ta capping layer. A key feature is a subsequent surface treatment of the Ta capping layer in a transient vacuum chamber where a self-annealing occurs and a surfactant layer is formed on the Ta surface. The resulting smooth and flat Ta surface promotes a smooth and flat surface in the MTJ layers which are subsequently formed on the surfactant layer. For a 0.3×0.6 micron MTJ bit size, a 35 to 40 Angstrom thick NiFe(18%) free layer, an AlOx barrier layer generated from a ROX oxidation of an 9 to 10 Angstrom thick Al layer, and a Ru/Ta/Ru capping layer are employed to give a dR/R of >40% and an RA of about 4000 ohm-?m2.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: May 1, 2007
    Assignees: Headway Technologies, Inc., Applied Spintronics, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong, Mao-Min Chen, Liubo Hong, Min Li
  • Structure and method to fabricate high performance MTJ devices for MRAM applications
    Patent number: 7208807
    Abstract: A high performance MTJ in an MRAM array is disclosed in which the bottom conductor has an amorphous Ta capping layer. A key feature is a surfactant layer comprised of oxygen that is formed on the Ta surface. The resulting smooth and flat Ta capping layer promotes a smooth and flat surface in the MTJ layers which are subsequently formed on the surfactant layer. For a 0.3×0.6 micron MTJ bit size, a 35 to 40 Angstrom thick NiFe(18%) free layer, an AlOx barrier layer generated from a ROX oxidation of an 9 to 10 Angstrom thick Al layer, and a Ru/Ta/Ru capping layer are employed to give a dR/R of >40% and an RA of about 4000 ohm-?m2. The MTJ configuraton is extendable to a 0.2×0.4 micron MTJ bit size.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: April 24, 2007
    Assignees: Headway Technologies, Inc., Applied Spintronics, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong, Mao-Min Chen, Liubo Hong, Min Li
  • Process and structure to fabricate spin valve heads for ultra-high recording density application
    Patent number: 7201827
    Abstract: A method for forming a bottom spin-valve GMR sensor having ultra-thin layers of high density and smoothness and possessing oxygen surfactant layers as a result of the layers being sputtered in a mixture of Ar and O2. A particularly novel feature of the method is the use of a sputtering chamber with an ultra-low base pressure and correspondingly ultra-low pressure mixtures of Ar and O2 sputtering gas (<0.5 millitorr) in which the admixed oxygen has a partial pressure of less than 5×10?9 torr.
    Type: Grant
    Filed: September 12, 2003
    Date of Patent: April 10, 2007
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Shield structure design to improve the stability of an MR head
    Patent number: 7180712
    Abstract: A method for forming a laminated shield to improve the stability and performance of an MR read head and the MR read head formed using that shield. The shield consists of two layers of ferromagnetic material separated by a layer of ruthenium, allowing the ferromagnetic layers to form an antiferromagnetic configuration by means of a quantum mechanical exchange interaction. The antiferromagnetic configuration has a stable domain structure and a magnetization that forms closed loops around the shield edges thereby reducing noise in the readback signal and reducing disturbances to the magnetic state of the sensor element.
    Type: Grant
    Filed: February 28, 2000
    Date of Patent: February 20, 2007
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Simon H. Liao, Cheng T. Horng, Kochan Ju
  • Method for fabricating a patterned, synthetic transverse exchange biased GMR sensor
    Patent number: 7152304
    Abstract: Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.
    Type: Grant
    Filed: January 14, 2005
    Date of Patent: December 26, 2006
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Min Li, Ru-Ying Tong, Yun-Fei Li, You Fong Zheng, Simon Liao, Kochan Ju, Cherng Chyi Han
  • Method for fabricating a patterned, synthetic transversely exchanged biased GMR sensor
    Patent number: 7134186
    Abstract: Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.
    Type: Grant
    Filed: January 14, 2005
    Date of Patent: November 14, 2006
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Min Li, Ru-Ying Tong, Yun-Fei Li, You Fong Zheng, Simon Liao, Kochan Ju, Cherng Chyi Han
  • Structure/method to fabricate a high performance magnetic tunneling junction MRAM
    Patent number: 7122852
    Abstract: An MTJ (magnetic tunneling junction) MRAM (magnetic random access memory) cell is formed on a conducting lead and magnetic keeper layer that is capped by a sputter-etched Ta layer. The Ta layer has a smooth surface as a result of the sputter-etching and that smooth surface promotes the subsequent formation of a lower electrode (pinning/pinned layer) with smooth, flat layers and a radical oxidized (ROX) Al tunneling barrier layer which is ultra-thin, smooth, and to has a high breakdown voltage. A seed layer of NiCr is formed on the sputter-etched layer of Ta. The resulting device has generally improved performance characteristics in terms of its switching characteristics, GMR ratio and junction resistance.
    Type: Grant
    Filed: May 12, 2004
    Date of Patent: October 17, 2006
    Assignees: Headway Technologies, Inc., Applied Spintronics, Inc.
    Inventors: Cheng T. Horng, Mao-Min Chen, Liubo Hong, Ru-Ying Tong
  • Magnetic assist read track-width definition for a lead overlay top spin-valve GMR head
    Patent number: 7072151
    Abstract: A method for forming a top spin-valve SyAP GMR read sensor having a novel conductive lead overlay configuration and the sensor so formed. The lead overlay electrically contacts the sensor at a position within the SyAP pinned layer, thus simultaneously assuring improved electrical contact and destroying the GMR properties of the sensor at the junction to improve the definition of the sensor track width.
    Type: Grant
    Filed: February 19, 2004
    Date of Patent: July 4, 2006
    Assignee: Headway Technologies, Inc.
    Inventors: Charles C. Lin, Cheng T. Horng, Min Li, Kochan Ju
  • CPP GMR read head
    Patent number: 7068478
    Abstract: Replacing ruthenium with rhodium as the AFM coupling layer in a synthetically pinned CPP GMR structure enables the AP1/AP2 thicknesses to be increased. This results in improved stability and allows the free layer and AFM layer thicknesses to be decreased, leading to an overall improvement in the device performance. Another key advantage of this structure is that the magnetic annealing requirements (to establish antiparallelism between AP1 and AP2) can be significantly relaxed.
    Type: Grant
    Filed: July 31, 2003
    Date of Patent: June 27, 2006
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Kunliang Zhang, Rachid Sbiaa, Cheng T. Horng, Simon Liao, Kochan Ju
  • Robust hard bias/conductor lead structures for future GMR heads
    Patent number: 7061730
    Abstract: A spin-valve magnetoresistive read element has a thin conductive lead layer of high sheet conductivity, high hardness, high melting point, high corrosion resistance and lacking the propensity for smearing, oozing, electromigration and nodule formation. Said lead layer is formed upon the hard magnetic longitudinal bias layer of an abutted junction spin-valve type magnetoresistive read head and said read head is therefore suitable for reading high density recorded disks at high RPM.
    Type: Grant
    Filed: August 27, 2003
    Date of Patent: June 13, 2006
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Mao-Min Chen, Chen-Jung Chien, Cherng-Chyi Han, Chyu-Jiuh Torng, Ru-Ying Tong