Patents by Inventor Tanmay Kumar

Tanmay Kumar 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: 7719874
    Abstract: A passive element memory device is provided that includes memory cells comprised of a state change element in series with a steering element. Controlled pulse operations are used to perform resistance changes associated with set and reset operations in an array of memory cells. Selected memory cells in an array are switched to a target resistance state in one embodiment by applying a positive voltage pulse to selected first array lines while applying a negative voltage pulse to selected second array lines. An amplitude of voltage pulses can be increased while being applied to efficiently and safely switch the resistance of cells having different operating characteristics. The cells are subjected to reverse biases in embodiments to lower leakage currents and increase bandwidth. The amplitude and duration of voltage pulses are controlled, along with the current applied to selected memory cells in some embodiments.
    Type: Grant
    Filed: July 31, 2006
    Date of Patent: May 18, 2010
    Assignee: SanDisk 3D LLC
    Inventors: Roy E. Scheuerlein, Tanmay Kumar
  • Publication number: 20100110752
    Abstract: A method of making a nonvolatile memory device includes fabricating a diode in a low resistivity, programmed state without an electrical programming step. The memory device includes at least one memory cell. The memory cell is constituted by the diode and electrically conductive electrodes contacting the diode.
    Type: Application
    Filed: October 2, 2009
    Publication date: May 6, 2010
    Inventors: Tanmay Kumar, S. Brad Herner
  • Patent number: 7706169
    Abstract: A method of programming a nonvolatile memory device includes (i) providing a nonvolatile memory cell comprising a diode in series with at least one metal oxide, (ii) applying a first forward bias to change a resistivity state of the metal oxide from a first state to a second state; (iii) applying a second forward bias to change a resistivity state of the metal oxide from a second state to a third state; and (iv) applying a third forward bias to change a resistivity state of the metal oxide from a third state to a fourth state. The fourth resistivity state is higher than the third resistivity state, the third resistivity state is lower than the second resistivity state, and the second resistivity state is lower than the first resistivity state.
    Type: Grant
    Filed: December 27, 2007
    Date of Patent: April 27, 2010
    Assignee: SanDisk 3D LLC
    Inventor: Tanmay Kumar
  • Publication number: 20100078759
    Abstract: A metal-insulator diode is disclosed. In one aspect, the metal-insulator diode comprises first and second electrode and first and second insulators arraigned as follows. An insulating region has a trench formed therein. The trench has a bottom and side walls. The first electrode, which comprises a first metal, is on the side walls and over the bottom of the trench. A first insulator has a first interface with the first electrode. At least a portion of the first insulator is within the trench. A second insulator has a second interface with the first insulator. At least a portion of the second insulator is within the trench. The second electrode, which comprises a second metal, is in contact with the second insulator. The second electrode at least partially fills the trench.
    Type: Application
    Filed: September 29, 2008
    Publication date: April 1, 2010
    Inventors: Deepak C. Sekar, Tanmay Kumar, Peter Rabkin, Er-Xuan Ping, Xiying Chen
  • Publication number: 20100078758
    Abstract: A metal-insulator diode is disclosed. In one aspect, the metal-insulator diode comprises a first electrode comprising a first metal, a first region comprising a first insulating material, a second region comprising a second insulating material, and a second electrode comprising a second metal. The first region and the second region reside between the first electrode and the second electrode. The second insulating material is doped with nitrogen. Note that the second insulating material may have an interface with either the first electrode or the second electrode.
    Type: Application
    Filed: September 29, 2008
    Publication date: April 1, 2010
    Inventors: Deepak C. Sekar, Tanmay Kumar, Peter Rabkin, Xiying Chen
  • Patent number: 7660181
    Abstract: A method of making a nonvolatile memory device includes forming a first electrode, forming at least one nonvolatile memory cell comprising a first diode portion, a second diode portion and an antifuse separating the first diode portion from the second diode portion, and forming a second electrode over the at least one nonvolatile memory cell.
    Type: Grant
    Filed: June 28, 2007
    Date of Patent: February 9, 2010
    Assignee: SanDisk 3D LLC
    Inventors: Tanmay Kumar, S. Brad Herner
  • Publication number: 20100006812
    Abstract: Memory devices including a carbon-based resistivity-switchable material, and methods of forming such memory devices are provided, the methods including introducing a processing gas into a processing chamber, wherein the processing gas includes a hydrocarbon compound and a carrier gas, and generating a plasma of the processing gas to deposit a layer of the carbon-based switchable material on a substrate within the processing chamber. Numerous additional aspects are provided.
    Type: Application
    Filed: July 8, 2009
    Publication date: January 14, 2010
    Applicant: SanDisk 3D LLC
    Inventors: Huiwen Xu, Xiying Chen, Roy E. Scheuerlein, Er-Xuan Ping, Tanmay Kumar, Alper Ilkbahar
  • Patent number: 7618850
    Abstract: A method of making a nonvolatile memory device includes fabricating a diode in a low resistivity, programmed state without an electrical programming step. The memory device includes at least one memory cell. The memory cell is constituted by the diode and electrically conductive electrodes contacting the diode.
    Type: Grant
    Filed: March 30, 2007
    Date of Patent: November 17, 2009
    Assignee: SanDisk 3D LLC
    Inventors: Tanmay Kumar, S. Brad Herner
  • Publication number: 20090272961
    Abstract: This disclosure provides a method of fabricating a semiconductor device layer and associated memory cell structures. By performing a surface treatment process (such as ion bombardment) of a semiconductor device layer to create defects having a deliberate depth profile, one may create multistable memory cells having more consistent electrical parameters. For example, in a resistive-switching memory cell, one may obtain a tighter distribution of set and reset voltages and lower forming voltage, leading to improved device yield and reliability. In at least one embodiment, the depth profile is selected to modulate the type of defects and their influence on electrical properties of a bombarded metal oxide layer and to enhance uniform defect distribution.
    Type: Application
    Filed: December 29, 2008
    Publication date: November 5, 2009
    Inventors: Michael Miller, Prashant Phatak, Tony Chiang, Xiying Chen, April Schricker, Tanmay Kumar
  • Publication number: 20090268508
    Abstract: One embodiment of the invention provides a semiconductor diode device including a first conductivity type region, a second conductivity type region, where the second conductivity type is different from the first conductivity type, an intrinsic region located between the first conductivity type region and the second conductivity type region; a first halo region of the first conductivity type located between the second conductivity type region and the intrinsic region, and optionally a second halo region of the second conductivity type located between the first conductivity type region and the intrinsic region.
    Type: Application
    Filed: April 29, 2008
    Publication date: October 29, 2009
    Inventors: Xiying Chen, Mark H. Clark, S. Brad Herner, Tanmay Kumar
  • Publication number: 20090257265
    Abstract: A nonvolatile memory cell includes a steering element located in series with a storage element. The storage element includes a carbon material and the memory cell includes a rewritable cell having multiple memory levels.
    Type: Application
    Filed: May 27, 2008
    Publication date: October 15, 2009
    Inventors: Xiying Chen, Bing K. Yen, Dat Nguyen, Huiwen Xu, George Samachisa, Tanmay Kumar, Er-Xuan Ping
  • Publication number: 20090258462
    Abstract: The invention provides for polysilicon vias connecting conductive polysilicon layers formed at different heights. Polysilicon vias are advantageously used in a monolithic three dimensional memory array of charge storage transistors. Polysilicon vias according to the present invention can be used, for example, to connect the channel layer of a first device level of charge storage transistor memory cells to the channel layer of a second device layer of such cells formed above the first device level. Similarly, vias according to the present invention can be used to connect the wordline of a first device level of charge storage transistor memory cells to the channel layer of a second device layer of such cells.
    Type: Application
    Filed: June 22, 2009
    Publication date: October 15, 2009
    Inventors: Michael W. Konevecki, Usha Raghuram, Maitreyee Mahajani, Sucheta Nallamothu, Andrew J. Walker, Tanmay Kumar
  • Publication number: 20090257266
    Abstract: A method of programming a nonvolatile memory cell includes applying at least one initialization pulse having a duration of at least 1 ms, followed by applying plural programming pulses having a duration of less than 1 ms. The cell includes a steering element located in series with a storage element, and the storage element includes a carbon material.
    Type: Application
    Filed: May 27, 2008
    Publication date: October 15, 2009
    Inventors: Xiying Chen, Tanmay Kumar
  • Publication number: 20090258135
    Abstract: A method of making a nonvolatile memory cell includes forming a steering element and forming a carbon resistivity switching material storage element by coating a carbon containing colloid.
    Type: Application
    Filed: August 7, 2008
    Publication date: October 15, 2009
    Inventors: Tanmay Kumar, Er-Xuan Ping, Alper Ilkbahar
  • Publication number: 20090258489
    Abstract: A method of making a non-volatile memory device includes forming a first electrode, forming a steering element, forming at least one feature, forming a carbon resistivity switching material on at least one sidewall of the at least one feature such that the carbon resistivity switching material electrically contacts the steering element, and forming a second electrode.
    Type: Application
    Filed: May 27, 2008
    Publication date: October 15, 2009
    Inventors: Xiying Chen, Chuanbin Pan, Tanmay Kumar, Er-Xuan Ping
  • Publication number: 20090230571
    Abstract: A monolithic three dimensional semiconductor device structure includes a first layer including a first occurrence of a first reference mark at a first location, and a second layer including a second occurrence of the first reference mark at a second location, wherein the second location is substantially directly above the first location. The device structure also includes an intermediate layer between the first layer and the second layer, the intermediate layer including a blocking structure, wherein the blocking structure is vertically interposed between the first occurrence of the first reference mark and the second occurrence of the first reference mark. Other aspects are also described.
    Type: Application
    Filed: May 22, 2009
    Publication date: September 17, 2009
    Applicant: SANDISK 3D LLC
    Inventors: Yung-Tin Chen, Christopher J. Petti, Steven J. Radigan, Tanmay Kumar
  • Patent number: 7566974
    Abstract: The invention provides for polysilicon vias connecting conductive polysilicon layers formed at different heights. Polysilicon vias are advantageously used in a monolithic three dimensional memory array of charge storage transistors. Polysilicon vias according to the present invention can be used, for example, to connect the channel layer of a first device level of charge storage transistor memory cells to the channel layer of a second device layer of such cells formed above the first device level. Similarly, vias according to the present invention can be used to connect the wordline of a first device level of charge storage transistor memory cells to the channel layer of a second device layer of such cells.
    Type: Grant
    Filed: September 29, 2004
    Date of Patent: July 28, 2009
    Assignee: SanDisk 3D, LLC
    Inventors: Michael W. Konevecki, Usha Raghuram, Maitreyee Mahajani, Tanmay Kumar, Sucheta Nallamothu, Andrew J. Walker
  • Publication number: 20090168486
    Abstract: A method of programming a nonvolatile memory device includes (i) providing a nonvolatile memory cell comprising a diode in series with at least one metal oxide, (ii) applying a first forward bias to change a resistivity state of the metal oxide from a first state to a second state; (iii) applying a second forward bias to change a resistivity state of the metal oxide from a second state to a third state; and (iv) applying a third forward bias to change a resistivity state of the metal oxide from a third state to a fourth state. The fourth resistivity state is higher than the third resistivity state, the third resistivity state is lower than the second resistivity state, and the second resistivity state is lower than the first resistivity state.
    Type: Application
    Filed: December 27, 2007
    Publication date: July 2, 2009
    Inventor: Tanmay Kumar
  • Patent number: 7553611
    Abstract: In formation of monolithic three dimensional memory arrays, a photomask may be used more than once. Reuse of a photomask creates second, third or more instances of reference marks used by the stepper to achieve alignment (alignment marks) and to measure alignment achieved (overlay marks) directly above prior instances of the same reference mark. The prior instances of the same reference mark may cause interference with the present instance of the reference mark, complicating alignment and measurement. Using the methods of the present invention, blocking structure is created vertically interposed between subsequent instances of the same reference mark, preventing interference.
    Type: Grant
    Filed: March 31, 2005
    Date of Patent: June 30, 2009
    Assignee: Sandisk 3D LLC
    Inventors: Yung-Tin Chen, Christopher J Petti, Steven J Radigan, Tanmay Kumar
  • Publication number: 20090104756
    Abstract: A method is described to form a rewriteable memory cell including a diode and an oxide layer, wherein the resistivity of the oxide layer can be reversibly switched. In preferred embodiments, the oxide layer is a grown oxide. The diode is preferably formed of polysilicon which has been crystallized in contact with a silicide which has a close lattice match to silicon. The silicide provides a crystallization template such that the polysilicon is large-grained with few defects, and thus relatively low-resistivity. In preferred embodiments, a monolithic three dimensional memory array can be formed, in which multiple memory levels of such rewriteable memory cells are monolithically formed vertically stacked above a substrate.
    Type: Application
    Filed: June 29, 2007
    Publication date: April 23, 2009
    Inventor: TANMAY KUMAR