Patents by Inventor Vidyut Gopal
Vidyut Gopal 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: 8704203Abstract: Embodiments of the invention include nonvolatile memory elements and memory devices comprising the nonvolatile memory elements. Methods for forming the nonvolatile memory elements are also disclosed. The nonvolatile memory element comprises a first electrode layer, a second electrode layer, and a plurality of layers of an oxide disposed between the first and second electrode layers. One of the oxide layers has linear resistance and substoichiometric composition, and the other oxide layer has bistable resistance and near-stoichiometric composition. Preferably, the sum of the two oxide layer thicknesses is between about 20 ? and about 100 ?, and the oxide layer with bistable resistance has a thickness between about 25% and about 75% of the total thickness. In one embodiment, the oxide layers are formed using reactive sputtering in an atmosphere with controlled flows of argon and oxygen.Type: GrantFiled: August 20, 2013Date of Patent: April 22, 2014Assignees: Intermolecular, Inc., Kabushiki Kaisha Toshiba, Sandisk 3D LLCInventors: Hieu Pham, Vidyut Gopal, Imran Hashim, Tim Minvielle, Yun Wang, Takeshi Yamaguchi, Hong Sheng Yang
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Publication number: 20140078808Abstract: Provided are nonvolatile memory assemblies each including a resistive switching layer and current steering element. The steering element may be a transistor connected in series with the switching layer. Resistance control provided by the steering element allows using switching layers requiring low switching voltages and currents. Memory assemblies including such switching layers are easier to embed into integrated circuit chips having other low voltage components, such as logic and digital signal processing components, than, for example, flash memory requiring much higher switching voltages. In some embodiments, provided nonvolatile memory assemblies operate at switching voltages less than about 3.0V and corresponding currents less than 50 microamperes. A memory element may include a metal rich hafnium oxide disposed between a titanium nitride electrode and doped polysilicon electrode. One electrode may be connected to a drain or source of the transistor, while another electrode is connected to a signal line.Type: ApplicationFiled: September 17, 2012Publication date: March 20, 2014Applicant: Intermolecular, Inc.Inventors: Imran Hashim, Tony Chiang, Vidyut Gopal, Yun Wang
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Publication number: 20140073107Abstract: Embodiments of the invention generally relate to nonvolatile memory devices, such as a ReRAM cells, and methods for manufacturing such memory devices, which includes optimized, atomic layer deposition (ALD) processes for forming metal oxide film stacks. The metal oxide film stacks contain a metal oxide coupling layer disposed on a metal oxide host layer, each layer having different grain structures/sizes. The interface disposed between the metal oxide layers facilitates oxygen vacancy movement. In many examples, the interface is a misaligned grain interface containing numerous grain boundaries extending parallel to the electrode interfaces, in contrast to the grains in the bulk film extending perpendicular to the electrode interfaces. As a result, oxygen vacancies are trapped and released during switching without significant loss of vacancies.Type: ApplicationFiled: May 17, 2013Publication date: March 13, 2014Applicant: Intermolecular Inc.Inventors: Yun Wang, Tony P. Chiang, Vidyut Gopal, Imran Hashim, Dipankar Pramanik
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Patent number: 8658511Abstract: Provided are methods for etching resistive switching and electrode layers in resistive random access memory (ReRAM) cells. Both types of layers are etched in the same operation. This approach simplifies processing in comparison to conventional etching, in which each layer is etched individually. The composition of etchants and process conditions are specifically selected to provide robust and effective etching of both types of layers. The two etching rates may be comparable and may be substantially the same, in some embodiments. Plasma etching involving tri-fluoro-methane and oxygen containing etchants may be used on electrode materials, such as titanium nitride, platinum, and ruthenium, and on resistive switching materials, such as oxides of transition metals. For example, a combination of titanium nitride and hafnium oxide may be etched using such processes. In some embodiments, an etched stack includes a third layer, which may function as a current limiter in ReRAM cells.Type: GrantFiled: December 20, 2012Date of Patent: February 25, 2014Assignee: Intermolecular, Inc.Inventors: Frederick Carlos Fulgenico, Vidyut Gopal, Jinhong Tong
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Publication number: 20140038380Abstract: A nonvolatile memory element is disclosed comprising a first electrode, a near-stoichiometric metal oxide memory layer having bistable resistance, and a second electrode in contact with the near-stoichiometric metal oxide memory layer. At least one electrode is a resistive electrode comprising a sub-stoichiometric transition metal nitride or oxynitride, and has a resistivity between 0.1 and 10 ?cm. The resistive electrode provides the functionality of an embedded current-limiting resistor and also serves as a source and sink of oxygen vacancies for setting and resetting the resistance state of the metal oxide layer. Novel fabrication methods for the second electrode are also disclosed.Type: ApplicationFiled: September 4, 2013Publication date: February 6, 2014Applicants: Kabushiki Kaisha Toshiba, Intermolecular Inc.Inventors: Hieu Pham, Vidyut Gopal, Imran Hashim, Tim Minvielle, Dipankar Pramanik, Yun Wang, Takeshi Yamaguchi, Hong Sheng Yang
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Publication number: 20140014172Abstract: A solar cell may comprise a stack of thin continuous epitaxial single crystal solar cell layers on a single crystal wafer, and a handling layer on the stack, the handling layer having a waffle-shaped structure with an array of either square or circular apertures, wherein the handling layer includes electrical contacts to the stack. The solar cell may comprise a boundary layer between the stack and the handling layer, the boundary layer being attached to both the stack and the handling layer, and the boundary layer being greater than 10 nanometers thick and parallel to the layers in the stack. The waffle-shaped structure may include perpendicular sets of first and second parallel ridges, wherein at least one of the sets is aligned at a small angle to a cleavage plane of the single crystal wafer.Type: ApplicationFiled: July 8, 2013Publication date: January 16, 2014Inventors: Ananda H. Kumar, Tirunelveli S. Ravi, Vidyut Gopal
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Publication number: 20130334490Abstract: Embodiments of the invention include nonvolatile memory elements and memory devices comprising the nonvolatile memory elements. Methods for forming the nonvolatile memory elements are also disclosed. The nonvolatile memory element comprises a first electrode layer, a second electrode layer, and a plurality of layers of an oxide disposed between the first and second electrode layers. One of the oxide layers has linear resistance and substoichiometric composition, and the other oxide layer has bistable resistance and near-stoichiometric composition. Preferably, the sum of the two oxide layer thicknesses is between about 20 ? and about 100 ?, and the oxide layer with bistable resistance has a thickness between about 25% and about 75% of the total thickness. In one embodiment, the oxide layers are formed using reactive sputtering in an atmosphere with controlled flows of argon and oxygen.Type: ApplicationFiled: August 20, 2013Publication date: December 19, 2013Applicants: Intermolecular Inc., SanDisk 3D LLC, Kabushiki Kaisha ToshibaInventors: Hieu Pham, Vidyut Gopal, Imran Hashim, Tim Minvielle, Yun Wang, Takeshi Yamaguchi, Hong Sheng Yang
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Publication number: 20130334484Abstract: Embodiments of the invention generally relate to nonvolatile memory devices and methods for manufacturing such memory devices. The methods for forming improved memory devices, such as a ReRAM cells, provide optimized, atomic layer deposition (ALD) processes for forming a metal oxide film stack having a metal oxide buffer layer disposed on or over a metal oxide bulk layer. The metal oxide bulk layer contains a metal-rich oxide material and the metal oxide buffer layer contains a metal-poor oxide material. The metal oxide bulk layer is less electrically resistive than the metal oxide buffer layer since the metal oxide bulk layer is less oxidized or more metallic than the metal oxide buffer layer. In one example, the metal oxide bulk layer contains a metal-rich hafnium oxide material and the metal oxide buffer layer contains a metal-poor zirconium oxide material.Type: ApplicationFiled: August 21, 2013Publication date: December 19, 2013Applicants: Intermolecular Inc., SanDisk 3D LLC, Kabushiki Kaisha ToshibaInventors: Yun Wang, Tony P. Chiang, Vidyut Gopal, Imran Hashim, Dipankar Pramanik
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Patent number: 8569104Abstract: Embodiments of the invention include nonvolatile memory elements and memory devices comprising the nonvolatile memory elements. Methods for forming the nonvolatile memory elements are also disclosed. The nonvolatile memory element comprises a first electrode layer, a second electrode layer, and a plurality of layers of an oxide disposed between the first and second electrode layers. One of the oxide layers has linear resistance and substoichiometric composition, and the other oxide layer has bistable resistance and near-stoichiometric composition. Preferably, the sum of the two oxide layer thicknesses is between about 20 ? and about 100 ?, and the oxide layer with bistable resistance has a thickness between about 25% and about 75% of the total thickness. In one embodiment, the oxide layers are formed using reactive sputtering in an atmosphere with controlled flows of argon and oxygen.Type: GrantFiled: February 7, 2012Date of Patent: October 29, 2013Assignees: Intermolecular, Inc., Kabushiki Kaisha Toshiba, SanDisk 3D LLCInventors: Hieu Pham, Vidyut Gopal, Imran Hashim, Tim Minvielle, Yun Wang, Takeshi Yamaguchi, Hong Sheng Yang
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Patent number: 8546275Abstract: Embodiments of the invention generally relate to nonvolatile memory devices and methods for manufacturing such memory devices. The methods for forming improved memory devices, such as a ReRAM cells, provide optimized, atomic layer deposition (ALD) processes for forming a metal oxide film stack having a metal oxide buffer layer disposed on or over a metal oxide bulk layer. The metal oxide bulk layer contains a metal-rich oxide material and the metal oxide buffer layer contains a metal-poor oxide material. The metal oxide bulk layer is less electrically resistive than the metal oxide buffer layer since the metal oxide bulk layer is less oxidized or more metallic than the metal oxide buffer layer. In one example, the metal oxide bulk layer contains a metal-rich hafnium oxide material and the metal oxide buffer layer contains a metal-poor zirconium oxide material.Type: GrantFiled: September 19, 2011Date of Patent: October 1, 2013Assignees: Intermolecular, Inc., Kabushiki Kaisha Toshiba, SanDisk 3D LLCInventors: Yun Wang, Vidyut Gopal, Imran Hashim, Dipankar Pramanik, Tony Chiang
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Publication number: 20130228735Abstract: A nonvolatile resistive memory element includes a host oxide formed from an interfacial oxide layer. The interfacial oxide layer is formed on the surface of a deposited electrode layer via in situ or post-deposition surface oxidation treatments. The switching performance of a resistive memory device based on such an interfacial oxide layer is equivalent or superior to the performance of a conventional resistive memory element.Type: ApplicationFiled: March 1, 2012Publication date: September 5, 2013Applicant: Intermolecular, Inc.Inventors: Randall Higuchi, Tony P. Chiang, Ryan Clarke, Vidyut Gopal, Imran Hashim, Robert Huertas, Yun Wang
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Publication number: 20130200323Abstract: A nonvolatile memory element is disclosed comprising a first electrode, a near-stoichiometric metal oxide memory layer having bistable resistance, and a second electrode in contact with the near-stoichiometric metal oxide memory layer. At least one electrode is a resistive electrode comprising a sub-stoichiometric transition metal nitride or oxynitride, and has a resistivity between 0.1 and 10 ? cm. The resistive electrode provides the functionality of an embedded current-limiting resistor and also serves as a source and sink of oxygen vacancies for setting and resetting the resistance state of the metal oxide layer. Novel fabrication methods for the second electrode are also disclosed.Type: ApplicationFiled: February 7, 2012Publication date: August 8, 2013Applicant: Intermolecular, Inc.Inventors: Hieu Pham, Vidyut Gopal, Imran Hashim, Dipankar Pramanik, Yun Wang, Hong Sheng Yang
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Publication number: 20130200324Abstract: Embodiments of the invention include nonvolatile memory elements and memory devices comprising the nonvolatile memory elements. Methods for forming the nonvolatile memory elements are also disclosed. The nonvolatile memory element comprises a first electrode layer, a second electrode layer, and a plurality of layers of an oxide disposed between the first and second electrode layers. One of the oxide layers has linear resistance and substoichiometric composition, and the other oxide layer has bistable resistance and near-stoichiometric composition. Preferably, the sum of the two oxide layer thicknesses is between about 20 ? and about 100 ?, and the oxide layer with bistable resistance has a thickness between about 25% and about 75% of the total thickness. In one embodiment, the oxide layers are formed using reactive sputtering in an atmosphere with controlled flows of argon and oxygen.Type: ApplicationFiled: February 7, 2012Publication date: August 8, 2013Applicant: Intermolecular, Inc.Inventors: Hieu Pham, Vidyut Gopal, Imran Hashim, Yun Wang, Hong Sheng Yang
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Patent number: 8481357Abstract: A method for fabricating a photovoltaic (PV) cell panel wherein all PV cells are formed simultaneously on a two-dimensional array of monocrystalline silicon mother wafers affixed to a susceptor is disclosed. Porous silicon separation layers are anodized in the surfaces of the mother wafers. The porous film is then smoothed to form a suitable surface for epitaxial film growth. An epitaxial reactor is used to grow n- and p-type films forming the PV cell structures. A glass/ceramic handling layer is then formed on the PV cell structures. The PV cell structures with handling layers are then exfoliated from the mother wafer. The array of mother wafers may be reused multiple times, thereby reducing materials costs for the completed solar panels. The glass/ceramic handling layers provide structural integrity to the thin epitaxial solar cells during the separation process and subsequent handling.Type: GrantFiled: April 23, 2010Date of Patent: July 9, 2013Assignee: Crystal Solar IncorporatedInventors: Ananda H. Kumar, Tirunelveli S. Ravi, Vidyut Gopal
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Patent number: 8466446Abstract: Embodiments of the invention generally relate to nonvolatile memory devices, such as a ReRAM cells, and methods for manufacturing such memory devices, which includes optimized, atomic layer deposition (ALD) processes for forming metal oxide film stacks. The metal oxide film stacks contain a metal oxide coupling layer disposed on a metal oxide host layer, each layer having different grain structures/sizes. The interface disposed between the metal oxide layers facilitates oxygen vacancy movement. In many examples, the interface is a misaligned grain interface containing numerous grain boundaries extending parallel to the electrode interfaces, in contrast to the grains in the bulk film extending perpendicular to the electrode interfaces. As a result, oxygen vacancies are trapped and released during switching without significant loss of vacancies.Type: GrantFiled: September 12, 2012Date of Patent: June 18, 2013Assignee: Intermolecular, Inc.Inventors: Yun Wang, Vidyut Gopal, Imran Hashim, Dipankar Pramanik, Tony Chiag
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Publication number: 20130134376Abstract: Atomic layer deposition (ALD) can be used to form a dielectric layer of zirconium oxide for use in a variety of electronic devices. Forming the dielectric layer includes depositing zirconium oxide using atomic layer deposition. A method of atomic layer deposition to produce a metal-rich metal oxide comprises the steps of providing a silicon substrate in a reaction chamber, pulsing a zirconium precursor for a predetermined time to deposit a first layer, and oxidizing the first layer with water vapor to produce the metal-rich metal oxide. The metal-rich metal oxide has superior properties for non-volatile resistive-switching memories.Type: ApplicationFiled: November 29, 2011Publication date: May 30, 2013Applicant: Intermolecular, Inc.Inventors: Jinhong Tong, Vidyut Gopal, Imran Hashim, Randall Higuchi, Albert Lee
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Publication number: 20130107604Abstract: Methods for producing RRAM resistive switching elements having optimal switching behavior include crystalline phase structural changes. Structural changes indicative of optimal switching behavior include hafnium oxide phases in an interfacial region between a resistive switching layer and an electrode.Type: ApplicationFiled: October 26, 2011Publication date: May 2, 2013Applicant: INTERMOLECULAR, INC.Inventors: Yun Wang, Tony Chiang, Imran Hashim, Vidyut Gopal
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Publication number: 20130071984Abstract: Embodiments of the invention generally relate to nonvolatile memory devices and methods for manufacturing such memory devices. The methods for forming improved memory devices, such as a ReRAM cells, provide optimized, atomic layer deposition (ALD) processes for forming a metal oxide film stack having a metal oxide buffer layer disposed on or over a metal oxide bulk layer. The metal oxide bulk layer contains a metal-rich oxide material and the metal oxide buffer layer contains a metal-poor oxide material. The metal oxide bulk layer is less electrically resistive than the metal oxide buffer layer since the metal oxide bulk layer is less oxidized or more metallic than the metal oxide buffer layer. In one example, the metal oxide bulk layer contains a metal-rich hafnium oxide material and the metal oxide buffer layer contains a metal-poor zirconium oxide material.Type: ApplicationFiled: September 19, 2011Publication date: March 21, 2013Applicant: INTERMOLECULAR, INC.Inventors: Yun Wang, Vidyut Gopal, Imran Hashim, Dipankar Pramanik, Tony Chiang
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Publication number: 20130065377Abstract: A resistive switching nonvolatile memory device having an interface layer disposed between a doped silicon electrode and a variable resistance layer fabricated in the nonvolatile memory device and methods of fabricating the same. In one embodiment, the interface layer is a high-k layer having a lower electrical EOT than native silicon oxide to act as a diffusion barrier between the variable resistance layer and the silicon electrode. Alternatively, the high-k interface layer may be formed by performing a nitrogen treatment on a fabricated silicon oxide layer. In another embodiment, the interface layer may be fabricated by performing a nitrogen or ozone treatment on the native oxide layer. In another embodiment, the interface layer is a fabricated silicon oxide layer resulting in an improved diffusion barrier between the variable resistance layer and the silicon electrode. In all embodiments, the interface layer also passivates the surface of the silicon electrode.Type: ApplicationFiled: September 9, 2011Publication date: March 14, 2013Applicant: INTERMOLECULAR, INC.Inventors: Vidyut Gopal, Yun Wang, Imran Hashim
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Publication number: 20130056702Abstract: Embodiments of the invention generally relate to nonvolatile memory devices, such as a ReRAM cells, and methods for manufacturing such memory devices, which includes optimized, atomic layer deposition (ALD) processes for forming metal oxide film stacks. The metal oxide film stacks contain a metal oxide coupling layer disposed on a metal oxide host layer, each layer having different grain structures/sizes. The interface disposed between the metal oxide layers facilitates oxygen vacancy movement. In many examples, the interface is a misaligned grain interface containing numerous grain boundaries extending parallel to the electrode interfaces, in contrast to the grains in the bulk film extending perpendicular to the electrode interfaces. As a result, oxygen vacancies are trapped and released during switching without significant loss of vacancies.Type: ApplicationFiled: September 12, 2012Publication date: March 7, 2013Applicant: Intermolecular, Inc.Inventors: Yun Wang, Vidyut Gopal, Imran Hashim, Dipankar Pramanik, Tony Chiang