Patents by Inventor Wipul Pemsiri Jayasekara

Wipul Pemsiri Jayasekara 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).

  • Patent number: 8835892
    Abstract: Methods in accordance with this invention form a microelectronic structure by forming a carbon nano-tube (“CNT”) layer, and forming a boron nitride layer (“BN liner”) above the CNT layer, wherein the BN liner comprises: (1) a first portion disposed above and in contact with the CNT layer; and/or (2) a second portion disposed in and/or around one or more carbon nano-tubes in the CNT layer. Numerous other aspects are provided.
    Type: Grant
    Filed: October 29, 2009
    Date of Patent: September 16, 2014
    Assignee: SanDisk 3D LLC
    Inventor: Wipul Pemsiri Jayasekara
  • Patent number: 8520424
    Abstract: A memory device in a 3-D read and write memory includes memory cells. Each memory cell includes a resistance-switching memory element (RSME) in series with a steering element. The RSME has first and second resistance-switching layers on either side of a conductive intermediate layer, and first and second electrodes at either end of the RSME. The first and second resistance-switching layers can both have a bipolar or unipolar switching characteristic. In a set or reset operation of the memory cell, an ionic current flows in the resistance-switching layers, contributing to a switching mechanism. An electron flow, which does not contribute to the switching mechanism, is reduced due to scattering by the conductive intermediate layer, to avoid damage to the steering element. Particular materials and combinations of materials for the different layers of the RSME are provided.
    Type: Grant
    Filed: June 9, 2011
    Date of Patent: August 27, 2013
    Assignee: SanDisk 3D LLC
    Inventors: Franz Kreupl, Abhijit Bandyopadhyay, Yung-Tin Chen, Chu-Chen Fu, Wipul Pemsiri Jayasekara, James Kai, Raghuveer S. Makala, Peter Rabkin, George Samachisa, Jingyan Zhang
  • Patent number: 8421050
    Abstract: Methods in accordance with this invention form a microelectronic structure by forming a carbon nano-tube (“CNT”) layer, and forming a carbon layer (“carbon liner”) above the CNT layer, wherein the carbon liner comprises: (1) a first portion disposed above and in contact with the CNT layer; and/or (2) a second portion disposed in and/or around one or more carbon nano-tubes in the CNT layer. Numerous other aspects are provided.
    Type: Grant
    Filed: October 29, 2009
    Date of Patent: April 16, 2013
    Assignee: SanDisk 3D LLC
    Inventors: Er-Xuan Ping, Huiwen Xu, April D. Schricker, Wipul Pemsiri Jayasekara
  • Patent number: 8266785
    Abstract: A method for manufacturing a magnetoresistive sensor having improved pinned layer stability at small track widths. The method includes providing a substrate, and depositing a plurality of sensor layers. A layer of material that is resistant to removal by chemical mechanical polishing (CMP stop layer) and an antireflective coating layer are deposited. A photoresist mask is formed on the antireflective layer, and a reactive ion etch (RIE) is performed to remove portions of the ion mill resistant mask that are not covered by the photoresist mask, the RIE being performed in a plasma chamber having a platen, the performing the RIE further comprising applying a platen power of at least 70 W. An ion milling is performed to remove a portion of the sensor layers, the ion milling being terminating before all of the sensor materials have been removed.
    Type: Grant
    Filed: November 12, 2007
    Date of Patent: September 18, 2012
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: James Mac Freitag, Wipul Pemsiri Jayasekara, Mustafa Michael Pinarbasi
  • Publication number: 20110310655
    Abstract: A memory device in a 3-D read and write memory includes memory cells. Each memory cell includes a resistance-switching memory element (RSME) in series with a steering element. The RSME has first and second resistance-switching layers on either side of a conductive intermediate layer, and first and second electrodes at either end of the RSME. The first and second resistance-switching layers can both have a bipolar or unipolar switching characteristic. In a set or reset operation of the memory cell, an ionic current flows in the resistance-switching layers, contributing to a switching mechanism. An electron flow, which does not contribute to the switching mechanism, is reduced due to scattering by the conductive intermediate layer, to avoid damage to the steering element. Particular materials and combinations of materials for the different layers of the RSME are provided.
    Type: Application
    Filed: June 9, 2011
    Publication date: December 22, 2011
    Inventors: Franz Kreupl, Abhijit Bandyopadhyay, Yung-Tin Chen, Chu-Chen Fu, Wipul Pemsiri Jayasekara, James Kai, Raghuveer S Makala, Peter Rabkin, George Samachisa, Jingyan Zhang
  • Patent number: 8037593
    Abstract: A method for manufacturing a magnetoresistive sensor that decreases the stack height of the sensor. The method includes forming a sensor structure having at its top, a Ru layer and a Ta layer over the Ru layer. An annealing process is performed to set the magnetization of the pinned layer of the sensor structure. After the annealing process has been completed and the Ta layer is no longer needed, an ion milling process is performed to remove the Ta layer.
    Type: Grant
    Filed: December 28, 2007
    Date of Patent: October 18, 2011
    Assignee: Hitachi Global Storage Technologies Netherlands, B.V.
    Inventors: Kuok San Ho, Ying Hong, Wipul Pemsiri Jayasekara, Daniele Mauri
  • Patent number: 7961440
    Abstract: A magnetoresistive sensor having a greatly reduced read gap. The sensor has a pinned layer structure formed above the free layer. A layer of antiferromagnetic material (AFM layer) is formed over the pinned layer structure and has a front edge disposed toward, but recessed from the air bearing surface. An electrically conductive, magnetic lead is formed over the pinned layer and AFM layer such that the lead fills a space between the AFM layer and the air bearing surface. In this way, the read gap is distance between the outermost portion of the pinned layer structure and free layer. The thickness of the AFM layer and capping layer are not included in the read gap.
    Type: Grant
    Filed: September 27, 2007
    Date of Patent: June 14, 2011
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Hardayal Singh Gill, Wipul Pemsiri Jayasekara
  • Patent number: 7881011
    Abstract: A magnetic structure, such as a pole tip, and method for forming the same includes forming a pole tip layer of magnetic material. A layer of polyimide precursor material is added above the pole tip layer and cured. A silicon-containing resist layer is added above the layer of polyimide precursor material and patterned. The resist layer is exposed to oxygen plasma for converting the resist into a glass-like material. Exposed portions of the cured polyimide precursor material are removed for exposing portions of the pole tip layer. The exposed portions of the pole tip layer are removed for forming a pole tip. Chemical mechanical polishing (CMP) can then be performed to remove any unwanted material remaining above the pole tip.
    Type: Grant
    Filed: August 9, 2007
    Date of Patent: February 1, 2011
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Richard Hsiao, Wipul Pemsiri Jayasekara, Jeffrey S. Lille
  • Patent number: 7881018
    Abstract: A differential giant magnetoresistive sensor for sensing a magnetic signal. The differential sensor has a structure configured to minimize spin torque noise. The differential magnetoresistive sensor includes first and second magnetoresistive sensor elements and a three lead structure including an inner lead sandwiched between the first and second sensor elements and first and second outer leads. each of the sensor elements includes an antiparallel coupled free layer structure with the free layer of each of the sensor elements preferably being positioned near the inner lead. The three lead structure allows sense current to be supplied to the sensor such that electrons travel first through the free layer of each sensor element and then through the pinned layer structure.
    Type: Grant
    Filed: September 5, 2007
    Date of Patent: February 1, 2011
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Hardayal Singh Gill, Wipul Pemsiri Jayasekara
  • Patent number: 7848065
    Abstract: A magnetoresistive sensor having magnetically anisotropic bias layers for biasing the free layer of the sensor. Hard bias structures for biasing the magnetization of the free layer are formed at either side of the sensor stack, and each of the hard bias structure includes a hard magnetic layer that has a magnetic anisotropy to enhance the stability of the biasing. The hard bias structure can include a Cr under-layer having a surface that has been treated by a low power angled ion milling to form it with an anisotropic surface texture. A layer of Cr—Mo alloy is formed over the Cr under-layer and the hard magnetic material layer is formed over the Cr—Mo alloy layer. The anisotropic surface texture of the Cr layer induces an aligned crystalline structure in the hard magnetic layer that causes the hard magnetic layer to have a magnetic anisotropy.
    Type: Grant
    Filed: December 22, 2006
    Date of Patent: December 7, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: James Mac Freitag, Mustafa Michael Pinarbasi, Wipul Pemsiri Jayasekara
  • Patent number: 7839606
    Abstract: A magnetic read head of either CIP or CPP configuration is disclosed having a read sensor having oxidized non-conductive regions. The read sensor has a front edge, a rear edge, a left-side edge and a right-side edge. For a CIP configuration, the front edge and the rear edge are oxidized to form non-conductive regions. For a CPP configuration, the left-side edge, the right-side edge, the front edge and the rear edge are oxidized to form non-conductive regions. Also disclosed are a disk drive including a read sensor having oxidized non-conductive regions, and a method of fabrication for a read sensor having oxidized non-conductive regions.
    Type: Grant
    Filed: June 9, 2006
    Date of Patent: November 23, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventor: Wipul Pemsiri Jayasekara
  • Patent number: 7839607
    Abstract: A method is presented for fabricating a CPP read head having a CPP read head sensor and a hard bias layer which includes forming a strip of sensor material in a sensor material region, and depositing strips of fast-milling dielectric material in first and second fast-milling dielectric material regions adjacent to the sensor material region. A protective layer and a layer of masking material are deposited on the strip of sensor material and the strips of fast-milling dielectric material to provide masked areas and exposed areas. A shaping source, such as an ion milling source, is provided which shapes the exposed areas. Hard bias material is then deposited on the regions of sensor material and fast-milling dielectric material to form caps on each of these regions. The caps of hard bias material and the masking material are then removed from each of these regions.
    Type: Grant
    Filed: August 7, 2007
    Date of Patent: November 23, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Robert E. Fontana, Jr., Ying Hong, Wipul Pemsiri Jayasekara, Howard Gordon Zolla
  • Patent number: 7820455
    Abstract: A method for manufacturing a magnetoresistive sensor that provides increased magnetoresistive performance. The method includes forming a series of sensor layers with at least one layer containing CoFeB, and having a first capping layer thereover. A high temperature annealing is performed to optimize the grains structure of the sensor layers. The first capping layer is then removed, such as by reactive ion etching (RIE). An antiferromagnetic layer is then deposited followed by a second capping layer. A second annealing is performed to set the magnetization of the pinned layer, the second annealing being performed at a lower temperature than the first annealing.
    Type: Grant
    Filed: March 31, 2008
    Date of Patent: October 26, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Hardayal Singh Gill, Wipul Pemsiri Jayasekara
  • Patent number: 7773349
    Abstract: In a CPP MR device such as a tunnel magnetoresistive (TMR) device, shoulders that have a magnetic moment that is matched to the magnetic moments of the free layer extend between the free layer and the S2 shield to provide an electrical path from one shoulder, through the shield, to the other shoulder for dissipating edge charges. Thus, a CPP MR device may include a seed stack, a pinned stack on the seed stack, and a tunnel barrier on the pinned stack. A free stack may be on the tunnel barrier, and the free stack can include a free sublayer separated from a magnetic shield and a path for dissipating edge charges in the free stack through the magnetic shield.
    Type: Grant
    Filed: February 10, 2006
    Date of Patent: August 10, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Robert Stanley Beach, Wipul Pemsiri Jayasekara, Vladimir Nikitin
  • Patent number: 7765676
    Abstract: A method for constructing a magnetoresistive sensor using an etch mask that is resistant to the material removal process used to define the sensor width and stripe height. The method may include the use of a Ta etch mask formed under a photoresist mask, and the use of an ion milling process to define the sensor. The etch mask remains substantially intact after performing the ion milling and therefore is readily removed by a later CMP process. The etch mask layer is also very resistant to high temperatures such as those used in a desired atomic layer deposition of alumina, which is used to deposit conformal layers of alumina around the sensor.
    Type: Grant
    Filed: November 18, 2004
    Date of Patent: August 3, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Marie-Claire Cyrille, Elizabeth Ann Dobisz, Wipul Pemsiri Jayasekara, Jui-Lung Li
  • Publication number: 20100108981
    Abstract: Methods in accordance with this invention form a microelectronic structure by forming a carbon nano-tube (“CNT”) layer, and forming a boron nitride layer (“BN liner”) above the CNT layer, wherein the BN liner comprises: (1) a first portion disposed above and in contact with the CNT layer; and/or (2) a second portion disposed in and/or around one or more carbon nano-tubes in the CNT layer. Numerous other aspects are provided.
    Type: Application
    Filed: October 29, 2009
    Publication date: May 6, 2010
    Applicant: SanDisk 3D LLC
    Inventor: Wipul Pemsiri Jayasekara
  • Publication number: 20100108976
    Abstract: Methods in accordance with this invention form microelectronic structures, such as non-volatile memories, that include carbon layers, such as carbon nanotube (“CNT”) films, in a way that protects the CNT film against damage and short-circuiting. Microelectronic structures, such as non-volatile memories, in accordance with this invention are formed in accordance with such techniques.
    Type: Application
    Filed: March 20, 2009
    Publication date: May 6, 2010
    Applicant: SANDISK 3D LLC
    Inventors: Wipul Pemsiri Jayasekara, April D. Schricker
  • Patent number: 7652855
    Abstract: A lead overlay design of a magnetic sensor is described with sensor and free layer dimensions such that the free layer is stabilized by the large demagnetization field due to the shape anisotropy. In one embodiment the giant magnetoresistive (GMR) effect under the leads is destroyed by removing the antiferromagnetic (AFM) and pinned layers above the free layer. The overlaid lead pads are deposited on the exposed spacer layer at the sides of the mask that defines the active region. In other embodiment a layer of electrically insulating material is deposited over the sensor to encapsulate it and thereby insulate it from contact with the hardbias structures. Various embodiments with self-aligned leads are also described. In a variation of the encapsulation embodiment, the insulating material is also deposited under the lead pads so the electrical current is channeled through the active region of the sensor and sidewall deposited lead pads.
    Type: Grant
    Filed: November 9, 2006
    Date of Patent: January 26, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: James Mac Freitag, David Eugene Heim, Kuok San Ho, Wipul Pemsiri Jayasekara, Kim Y. Lee, Tsann Lin, Jyh-Shuey Lo, Mustafa Michael Pinarbasi, Ching Hwa Tsang
  • Patent number: 7639456
    Abstract: A current perpendicular to plane (CPP) sensor and method of manufacturing such a sensor that prevents current shunting at the sides of the barrier/spacer layer due to redeposited material. A first ion mill is performed to remove at least the free layer. A quick glancing ion mill can be performed to remove the small amount of redep that may have accumulated on the sides of the free layer and barrier/spacer layer. Then an insulation layer is deposited to protect the sides of the free layer/barrier layer during subsequent manufacturing which can include further ion milling to define the rest of the sensor and another glancing ion mill to remove the redep formed by the further ion milling. This results in a sensor having no current shunting at the sides of the sensor and having no damage to the sensor layers.
    Type: Grant
    Filed: October 6, 2005
    Date of Patent: December 29, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Ying Hong, Wipul Pemsiri Jayasekara
  • Patent number: 7627942
    Abstract: A method for fabricating a magnetic write head with a coil with a high aspect ratio using a Chemical Vapor Deposition process such as Atomic Layer Deposition (ALD), High Speed ALD, Plasma Enhanced ALD (PEALD), Plasma Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD) to form encapsulating films over the coils without voids is disclosed. Materials which can be used for encapsulation include Al2O3, SiO2, AlN, Ta2O5, HfO2, ZrO2, and YtO3. The use of an ultra-conformal deposition process allows the pitch of the coils to be smaller than it is possible in the prior art. The method also allows materials with a smaller coefficient of thermal expansion than hardbake photoresist to be used with resulting improvements in thermal protrusion characteristics.
    Type: Grant
    Filed: March 25, 2005
    Date of Patent: December 8, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Richard Hsiao, Wipul Pemsiri Jayasekara, Howard Gordon Zolla