Patents by Inventor Ru-Ying Tong

Ru-Ying Tong 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).

  • High performance MTJ element for STT-RAM and method for making the same
    Publication number: 20090027810
    Abstract: We describe the structure and method of forming a STT-MTJ MRAM cell that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The device includes an IrMn pinning layer, a SyAP pinned layer, a naturally oxidized, crystalline MgO tunneling barrier layer that is formed on an Ar-ion plasma smoothed surface of the pinned layer and, in one embodiment, a free layer that comprises an amorphous layer of Co60Fe20B20. of approximately 20 angstroms thickness formed between two crystalline layers of Fe of 3 and 6 angstroms thickness respectively. The free layer is characterized by a low Gilbert damping factor and by very strong polarizing action on conduction electrons. The resulting cell has a low critical current, a high dR/R and a plurality of such cells will exhibit a low variation of both resistance and pinned layer magnetization angular dispersion.
    Type: Application
    Filed: July 23, 2007
    Publication date: January 29, 2009
    Inventors: Cheng T. Horng, Ru-Ying Tong, Chyu-Jiuh Torng, Witold Kula
  • MgO/NiFe MTJ for high performance MRAM application
    Patent number: 7479394
    Abstract: An improved tunneling barrier layer is formed for use in a MTJ device. This is accomplished by forming the tunneling barrier layer in two steps. First a layer of magnesium is deposited by DC sputtering and converted to magnesium oxide through radical oxidation. This is followed by a second, thinner, magnesium layer that is converted to magnesium oxide through normal oxidation. Optionally, there may also be a thin layer of magnesium on the two magnesium oxide layers.
    Type: Grant
    Filed: December 22, 2005
    Date of Patent: January 20, 2009
    Assignee: MagIC Technologies, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Spin transfer MRAM device with novel magnetic free layer
    Patent number: 7480173
    Abstract: A CPP MTJ MRAM element utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The device includes a tunneling barrier layer of MgO and a non-magnetic CPP layer of Cu or Cr and utilizes a novel free layer comprising a thin layer of Ta or Hf sandwiched by layers of CoFeB. The device is characterized by values of DR/R between approximately 95% and 105%.
    Type: Grant
    Filed: March 13, 2007
    Date of Patent: January 20, 2009
    Assignee: MagIC Technologies, Inc.
    Inventors: Yimin Guo, Cheng T. Horng, Ru-Ying Tong
  • Capping structure for enhancing dR/R of the MTJ device
    Patent number: 7449345
    Abstract: An MTJ in an MRAM array or in a TMR read head is comprised of a capping layer with a lower inter-diffusion barrier layer, an intermediate oxygen gettering layer, and an upper metal layer that contacts a top conductor. The composite capping layer is especially useful with a moderate spin polarization free layer such as a NiFe layer with a Fe content of about 17.5 to 20 atomic %. The capping layer preferably has a Ru/Ta/Ru configuration in which the lower Ru layer is about 10 to 30 Angstroms thick and the Ta layer is about 30 Angstroms thick. As a result, a high dR/R of about 40% is achieved with low magnetostriction less than about 1.0 E?6 in an MTJ in an MRAM array. Best results are obtained with an AlOx tunnel barrier layer formed by an in-situ ROX process on an 8 to 10 Angstrom thick Al layer.
    Type: Grant
    Filed: June 15, 2004
    Date of Patent: November 11, 2008
    Assignees: Headway Technologies, Inc., Applied Spintronics, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong, Liubo Hong, Min Li
  • Spin transfer MRAM device with novel magnetic synthetic free layer
    Publication number: 20080239589
    Abstract: We describe a CPP MTJ MRAM element that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The device includes a tunneling barrier layer of MgO and a non-magnetic CPP layer of Cu or Cr and utilizes a novel synthetic free layer having three ferromagnetic layers mutually exchange coupled in pairwise configurations. The free layer comprises an inner ferromagnetic and two outer ferromagnetic layers, with the inner layer being ferromagnetically exchange coupled to one outer layer and anti-ferromagnetically exchange coupled to the other outer layer. The ferromagnetic coupling is very strong across an ultra-thin layer of Ta, Hf or Zr of thickness preferably less than 0.4 nm.
    Type: Application
    Filed: March 26, 2007
    Publication date: October 2, 2008
    Inventors: Yimin Guo, Cheng T. Horng, Ru-Ying Tong
  • Spin transfer MRAM device with novel magnetic free layer
    Publication number: 20080225583
    Abstract: We describe a CPP MTJ MRAM element that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The device includes a tunneling barrier layer of MgO and a non-magnetic CPP layer of Cu or Cr and utilizes a novel free layer comprising a thin layer of Ta or Hf sandwiched by layers of CoFeB. The device is characterized by values of DR/R between approximately 95% and 105%.
    Type: Application
    Filed: March 13, 2007
    Publication date: September 18, 2008
    Inventors: Yimin Guo, Cheng T. Horng, Ru-Ying Tong
  • Novel SyAF structure to fabricate Mbit MTJ MRAM
    Publication number: 20080217710
    Abstract: A MTJ that minimizes error count (EC) while achieving high MR value, low magnetostriction, and a RA of about 1100 ?-?m2 for 1 Mbit MRAM devices is disclosed. The MTJ has a composite AP1 pinned layer made of a lower amorphous Co60Fe20B20 layer and an upper crystalline Co75Fe25 layer to promote a smoother and more uniform AlOx tunnel barrier. A “stronger oxidation” state is realized in the AlOx layer by depositing a thicker than normal Al layer or extending the ROX cycle time for Al oxidation and thereby reduces tunneling hot spots. The NiFe free layer has a low Fe content of about 8 to 21 atomic % and the Hf content in the NiFeHf capping layer is from 10 to 25 atomic %. A Ta hard mask is formed on the capping layer. EC (best) is reduced from >100 ppm to <10 ppm by using the preferred MTJ configuration.
    Type: Application
    Filed: March 8, 2007
    Publication date: September 11, 2008
    Inventors: Cheng T. Horng, Ru-Ying Tong, Chyu-Jiuh Torng, Guangli Liu
  • Process and structure to fabricate CPP spin valve heads for ultra-high recording density
    Patent number: 7423848
    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: July 27, 2007
    Date of Patent: September 9, 2008
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Novel magnetic tunnel junction (MTJ) to reduce spin transfer magnetization switching current
    Publication number: 20080179699
    Abstract: A MTJ that minimizes spin-transfer magnetization switching current (Jc) in a Spin-RAM to <1×106 A/cm2 is disclosed. The MTJ has a Co60Fe20B20/MgO/Co60Fe20B20 configuration where the CoFeB AP1 pinned and free layers are amorphous and the crystalline MgO tunnel barrier is formed by a ROX or NOX process. The capping layer preferably is a Hf/Ru composite where the lower Hf layer serves as an excellent oxygen getter material to reduce the magnetic “dead layer” at the free layer/capping layer interface and thereby increase dR/R, and lower He and Jc. The annealing temperature is lowered to about 280° C. to give a smoother CoFeB/MgO interface and a smaller offset field than with a 350° C. annealing. In a second embodiment, the AP1 layer has a CoFeB/CoFe configuration wherein the lower CoFeB layer is amorphous and the upper CoFe layer is crystalline to further improve dR/R and lower RA to ?10 ohm/?m2.
    Type: Application
    Filed: January 30, 2007
    Publication date: July 31, 2008
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Patterned, synthetic longitudinally exchange biased GMR sensor
    Patent number: 7400475
    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: July 15, 2008
    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 form bottom spin valves for ultra-high density
    Patent number: 7394625
    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: July 1, 2008
    Assignee: Headway Technologies, Inc.
    Inventors: Cheng T. Horng, Ru-Ying Tong
  • Free layer for CPP GMR having iron rich NiFe
    Patent number: 7390529
    Abstract: By using a free layer that includes a NiFe layer containing between 65 and 72 atomic percent iron, 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 26, 2004
    Date of Patent: June 24, 2008
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Cheng T. Horng, Cherng Chyi Han, Yu-Hsia Chen, Ru-Ying Tong
  • Seed/AFM combination for CCP GMR device
    Publication number: 20080112089
    Abstract: Improved CPP GMR devices have been fabricated by replacing the conventional seed layer (typically Ta) with a bilayer of NiCr on Ta, said seed being deposited on the NiFe layer that constitutes a magnetic shield. Additional improvement was also obtained by replacing the conventional non-magnetic spacer layer of copper with a sandwich structure of two copper layers with an NOL (nano-oxide layer) between them. A process for manufacturing the devices is also described.
    Type: Application
    Filed: January 9, 2008
    Publication date: May 15, 2008
    Inventors: Min Li, Cheng Horng, Cherng Han, Yue Liu, Yu-Hsia Chen, Ru-Ying Tong
  • Free layer for CPP GMR enhancement
    Publication number: 20080096051
    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: Application
    Filed: December 14, 2007
    Publication date: April 24, 2008
    Inventors: Min Li, Cheng Horng, Ru-Ying Tong
  • Bottom electrode for MRAM device and method to fabricate it
    Publication number: 20080090307
    Abstract: Formation of a bottom electrode for an MTJ device on a silicon nitride substrate is facilitated by including a layer of ruthenium near the silicon nitride surface. The ruthenium is a good electrical conductor and it responds differently from Ta and TaN to certain etchants. Adhesion to SiN is enhanced by using a TaN/NiCr bilayer as “glue”. Thus, said included layer of ruthenium may be used as an etch stop layer during the etching of Ta and/or TaN while the latter materials may be used to form a hard mask for etching the ruthenium without significant corrosion of the silicon nitride surface.
    Type: Application
    Filed: September 28, 2006
    Publication date: April 17, 2008
    Inventors: Rongfu Xiao, Cheng T. Horng, Ru-Ying Tong, Chyu-Jinh Torng, Tom Zhong, Witold Kula, Terry Kin Ting Ko, Wei Cao, Wai-Ming J. Kan, Liubo Hong
  • Hafnium doped cap and free layer for MRAM device
    Publication number: 20080088986
    Abstract: A high performance MTJ, and a process for manufacturing it, are described. A capping layer of NiFeHf is used to getter oxygen out of the free layer, thereby increasing the sharpness of the free layer-tunneling layer interface. The free layer comprises two NiFe layers whose magnetostriction constants are of opposite sign, thereby largely canceling one another.
    Type: Application
    Filed: October 17, 2006
    Publication date: April 17, 2008
    Inventors: Cheng T. Horng, Ru-Ying Tong, Chyu-Jiuh Torng, Witold Kula
  • Process of manufacturing a seed/AFM combination for a CPP GMR device
    Patent number: 7331100
    Abstract: An improved seed/AFM structure is formed by first depositing a layer of tantalum on the lower shield. A NiCr layer is then deposited on the Ta followed by a layer of IrMn. The latter functions effectively as an AFM for thicknesses in the 40-80 Angstrom range, enabling a reduced shield-to-shield spacing.
    Type: Grant
    Filed: July 7, 2004
    Date of Patent: February 19, 2008
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Cheng T. Horng, Cherng Chyi Han, Yue Liu, Yu-Hsia Chen, Ru-Ying Tong
  • 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