Patents by Inventor Donovan Lee

Donovan Lee 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: 9552991
    Abstract: A method of making a monolithic three dimensional NAND string includes providing a stack of alternating first material layers and second material layers different from the first material layer over a substrate, etching the stack to form at least one trench in the stack, forming a blocking dielectric over a side wall of the at least one trench, forming a charge storage layer over the blocking dielectric in the at least one trench, forming a tunnel dielectric over the charge storage layer in the at least one trench and forming a semiconductor channel over the tunnel dielectric in the at least one trench.
    Type: Grant
    Filed: April 30, 2014
    Date of Patent: January 24, 2017
    Assignee: SANDISK TECHNOLOGIES LLC
    Inventors: Akira Matsudaira, James Kai, Yuan Zhang, Vinod Purayath, Donovan Lee
  • Patent number: 9548311
    Abstract: Suspended charge storage regions are utilized for non-volatile storage to decrease parasitic interferences and increase charge retention in memory devices. Charge storage regions are suspended from an overlying intermediate dielectric material. The charge storage regions include an upper surface and a lower surface that extend in the row and column directions. The upper surface of the charge storage region is coupled to the overlying intermediate dielectric material. The lower surface faces the substrate surface and is separated from the substrate surface by a void. The charge storage region includes a first vertical sidewall and a second vertical sidewall that extend in the column direction and a third vertical sidewall and fourth vertical sidewall that extend in the row direction. The first, second, third, and fourth vertical sidewall are separated from neighboring features of the non-volatile memory by the void. The void may include a vacuum, air, gas, or a liquid.
    Type: Grant
    Filed: April 26, 2016
    Date of Patent: January 17, 2017
    Assignee: SanDisk Technologies LLC
    Inventors: Donovan Lee, Vinod R Purayath, James Kai
  • Patent number: 9543139
    Abstract: Methods for preventing line collapse during the fabrication of NAND flash memory and other microelectronic devices that utilize closely spaced device structures with high aspect ratios are described. In some embodiments, one or more mechanical support structures may be used to provide lateral support between closely spaced device structures to prevent collapsing of the closely spaced device structures during an etching process (e.g., during a word line etch). In one example, during fabrication of a NAND flash memory, one or more mechanical support structures may be in place prior to performing a high aspect ratio word line etch or may be formed during the word line etch. In some cases, the one or more mechanical support structures may comprise portions of an inter-poly dielectric (IPD) layer that were in place prior to performing the word line etch.
    Type: Grant
    Filed: April 7, 2014
    Date of Patent: January 10, 2017
    Assignee: SANDISK TECHNOLOGIES LLC
    Inventors: Akira Matsudaira, Donovan Lee
  • Publication number: 20160240546
    Abstract: Suspended charge storage regions are utilized for non-volatile storage to decrease parasitic interferences and increase charge retention in memory devices. Charge storage regions are suspended from an overlying intermediate dielectric material. The charge storage regions include an upper surface and a lower surface that extend in the row and column directions. The upper surface of the charge storage region is coupled to the overlying intermediate dielectric material. The lower surface faces the substrate surface and is separated from the substrate surface by a void. The charge storage region includes a first vertical sidewall and a second vertical sidewall that extend in the column direction and a third vertical sidewall and fourth vertical sidewall that extend in the row direction. The first, second, third, and fourth vertical sidewall are separated from neighboring features of the non-volatile memory by the void. The void may include a vacuum, air, gas, or a liquid.
    Type: Application
    Filed: April 26, 2016
    Publication date: August 18, 2016
    Applicant: SanDisk Technologies Inc.
    Inventors: Donovan Lee, Vinod R. Purayath, James Kai
  • Patent number: 9349740
    Abstract: Suspended charge storage regions are utilized for non-volatile storage to decrease parasitic interferences and increase charge retention in memory devices. Charge storage regions are suspended from an overlying intermediate dielectric material. The charge storage regions include an upper surface and a lower surface that extend in the row and column directions. The upper surface of the charge storage region is coupled to the overlying intermediate dielectric material. The lower surface faces the substrate surface and is separated from the substrate surface by a void. The charge storage region includes a first vertical sidewall and a second vertical sidewall that extend in the column direction and a third vertical sidewall and fourth vertical sidewall that extend in the row direction. The first, second, third, and fourth vertical sidewall are separated from neighboring features of the non-volatile memory by the void. The void may include a vacuum, air, gas, or a liquid.
    Type: Grant
    Filed: January 24, 2014
    Date of Patent: May 24, 2016
    Assignee: SanDisk Technologies Inc.
    Inventors: Donovan Lee, Vinod R Purayath, James Kai
  • Patent number: 9331181
    Abstract: A memory device and a method of making a memory device that includes a semiconductor channel, a tunnel dielectric layer located over the semiconductor channel, a floating gate located over the tunnel dielectric layer, the floating gate comprising a continuous layer of an electrically conductive material and at least one protrusion of an electrically conductive material facing the tunnel dielectric layer and electrically shorted to the continuous layer, a blocking dielectric region located over the floating gate, and a control gate located over the blocking dielectric layer.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: May 3, 2016
    Assignee: SANDISK TECHNOLOGIES INC.
    Inventors: Donovan Lee, James K. Kai, George Samachisa, Henry Chien, George Matamis, Vinod R. Purayath
  • Patent number: 9252151
    Abstract: A method of making a monolithic three dimensional NAND string including forming a stack of alternating layers of a first material and a second material over a substrate. The first material comprises an electrically insulating material and the second material comprises a semiconductor or conductor material. The method also includes etching the stack to form a front side opening in the stack, forming a blocking dielectric layer over the stack of alternating layers of a first material and a second material exposed in the front side opening, forming a semiconductor or metal charge storage layer over the blocking dielectric, forming a tunnel dielectric layer over the charge storage layer, forming a semiconductor channel layer over the tunnel dielectric layer, etching the stack to form a back side opening in the stack, removing at least a portion of the first material layers and portions of the blocking dielectric layer.
    Type: Grant
    Filed: February 18, 2014
    Date of Patent: February 2, 2016
    Assignee: SANDISK TECHNOLOGIES INC.
    Inventors: Henry Chien, Donovan Lee, Vinod R. Purayath, Yuan Zhang, James K. Kai, George Matamis
  • Patent number: 9230971
    Abstract: A method of making a NAND string includes forming a tunnel dielectric over a semiconductor channel, forming a charge storage layer over the tunnel dielectric, forming a blocking dielectric over the charge storage layer, and forming a control gate layer over the blocking dielectric. The method also includes patterning the control gate layer to form a plurality of control gates separated by trenches, and reacting a first material with exposed sidewalls of the plurality of control gates to form self aligned metal-first material compound sidewall spacers on the exposed sidewalls of the plurality of control gates.
    Type: Grant
    Filed: January 28, 2015
    Date of Patent: January 5, 2016
    Assignee: SANDISK TECHNOLOGIES INC.
    Inventors: Donovan Lee, Vinod Purayath, James Kai, George Matamis
  • Patent number: 9224746
    Abstract: A non-volatile memory system, comprising non-volatile storage device with word lines having an inverted T-shape over floating gates. The inverted T-shape shape has a wider bottom portion and a thinner top portion. The thinner top portion increases the separation between adjacent word lines relative to the separation between the wider bottom portions. An air gap may separate adjacent word lines. The thinner top portion of the word lines increases the path length between adjacent word lines. The likelihood of word line to word line short may be decreased by reducing the electric field between adjacent word lines.
    Type: Grant
    Filed: November 5, 2013
    Date of Patent: December 29, 2015
    Assignee: SanDisk Technologies Inc.
    Inventors: Vinod R. Purayath, James Kai, Donovan Lee, Yuan Zhang, Akira Matsudaira
  • Publication number: 20150318295
    Abstract: A method of making a monolithic three dimensional NAND string includes providing a stack of alternating insulating layers and control gate films over a major surface of a substrate. Each of the control gate films includes a middle layer located between a first control gate layer and a second control gate layer, the middle layer being a different material from the first and second control gate layers and from the insulating layers. The method also includes forming a front side opening in the stack, and forming a blocking dielectric, at least one charge storage region, a tunnel dielectric and a semiconductor channel in the front side opening in the stack.
    Type: Application
    Filed: April 30, 2014
    Publication date: November 5, 2015
    Applicant: SanDisk Technologies, Inc.
    Inventors: James Kai, Vinod Purayath, Donovan Lee, Akira Matsudaira
  • Publication number: 20150318298
    Abstract: A method of making a monolithic three dimensional NAND string includes providing a stack of alternating first material layers and second material layers different from the first material layer over a substrate, etching the stack to form at least one trench in the stack, forming a blocking dielectric over a side wall of the at least one trench, forming a charge storage layer over the blocking dielectric in the at least one trench, forming a tunnel dielectric over the charge storage layer in the at least one trench and forming a semiconductor channel over the tunnel dielectric in the at least one trench.
    Type: Application
    Filed: April 30, 2014
    Publication date: November 5, 2015
    Applicant: SanDisk Technologies, Inc.
    Inventors: Akira Matsudaira, James Kai, Yuan Zhang, Vinod Purayath, Donovan Lee
  • Patent number: 9177808
    Abstract: An embodiment relates to a memory device that includes a semiconductor channel, a tunnel dielectric located over the semiconductor channel, a charge storage region located over the tunnel dielectric, a blocking dielectric located over the charge storage region, and a control gate located over the blocking dielectric. An interface between the blocking dielectric and the control gate substantially prevents oxygen diffusion from the blocking dielectric into the control gate.
    Type: Grant
    Filed: May 22, 2014
    Date of Patent: November 3, 2015
    Assignee: SANDISK TECHNOLOGIES INC.
    Inventors: Vinod R. Purayath, James Kai, Donovan Lee, Akira Matsudaira, Yuan Zhang
  • Patent number: 9165940
    Abstract: A method of making a monolithic three dimensional NAND string, including providing a stack of alternating first material layers and second material layers different from the first material layer over a substrate, the stack comprising at least one opening containing a charge storage material comprising a silicide layer, a tunnel dielectric on the charge storage material in the at least one opening, and a semiconductor channel on the tunnel dielectric in the at least one opening, selectively removing the second material layers without removing the first material layers from the stack and forming control gates between the first material layers.
    Type: Grant
    Filed: November 12, 2014
    Date of Patent: October 20, 2015
    Assignee: SANDISK TECHNOLOGIES INC.
    Inventors: Henry Chien, Johann Alsmeier, George Samachisa, Henry Chin, George Matamis, Yuan Zhang, James Kai, Vinod Purayath, Donovan Lee
  • Publication number: 20150287733
    Abstract: Methods for preventing line collapse during the fabrication of NAND flash memory and other microelectronic devices that utilize closely spaced device structures with high aspect ratios are described. In some embodiments, one or more mechanical support structures may be used to provide lateral support between closely spaced device structures to prevent collapsing of the closely spaced device structures during an etching process (e.g., during a word line etch). In one example, during fabrication of a NAND flash memory, one or more mechanical support structures may be in place prior to performing a high aspect ratio word line etch or may be formed during the word line etch. In some cases, the one or more mechanical support structures may comprise portions of an inter-poly dielectric (IPD) layer that were in place prior to performing the word line etch.
    Type: Application
    Filed: April 7, 2014
    Publication date: October 8, 2015
    Applicant: SANDISK TECHNOLOGIES INC.
    Inventors: Akira Matsudaira, Donovan Lee
  • Publication number: 20150214235
    Abstract: Suspended charge storage regions are utilized for non-volatile storage to decrease parasitic interferences and increase charge retention in memory devices. Charge storage regions are suspended from an overlying intermediate dielectric material. The charge storage regions include an upper surface and a lower surface that extend in the row and column directions. The upper surface of the charge storage region is coupled to the overlying intermediate dielectric material. The lower surface faces the substrate surface and is separated from the substrate surface by a void. The charge storage region includes a first vertical sidewall and a second vertical sidewall that extend in the column direction and a third vertical sidewall and fourth vertical sidewall that extend in the row direction. The first, second, third, and fourth vertical sidewall are separated from neighboring features of the non-volatile memory by the void. The void may include a vacuum, air, gas, or a liquid.
    Type: Application
    Filed: January 24, 2014
    Publication date: July 30, 2015
    Applicant: SanDisk Technologies Inc.
    Inventors: Donovan Lee, Vinod R. Purayath, James Kai
  • Publication number: 20150137208
    Abstract: A method of making a NAND string includes forming a tunnel dielectric over a semiconductor channel, forming a charge storage layer over the tunnel dielectric, forming a blocking dielectric over the charge storage layer, and forming a control gate layer over the blocking dielectric. The method also includes patterning the control gate layer to form a plurality of control gates separated by trenches, and reacting a first material with exposed sidewalls of the plurality of control gates to form self aligned metal-first material compound sidewall spacers on the exposed sidewalls of the plurality of control gates.
    Type: Application
    Filed: January 28, 2015
    Publication date: May 21, 2015
    Inventors: Donovan Lee, Vinod Purayath, James Kai, George Matamis
  • Patent number: 8987802
    Abstract: A memory cell including a control gate located over a floating gate region. The floating gate region includes discrete doped semiconducting or conducting regions separated by an insulator and the discrete doped semiconducting or conducting regions have a generally cylindrical shape or a quasi-cylindrical shape.
    Type: Grant
    Filed: February 28, 2013
    Date of Patent: March 24, 2015
    Assignee: SanDisk Technologies Inc.
    Inventors: Donovan Lee, James Kai, Vinod Purayath, George Matamis, Steven J. Radigan
  • Patent number: 8987087
    Abstract: A method of making a monolithic three dimensional NAND string including forming a stack of alternating layers of a first material and a second material over a substrate. The first material comprises an electrically insulating material and the second material comprises a semiconductor or conductor material. The method also includes etching the stack to form a front side opening in the stack, forming a blocking dielectric layer over the stack of alternating layers of a first material and a second material exposed in the front side opening, forming a semiconductor or metal charge storage layer over the blocking dielectric, forming a tunnel dielectric layer over the charge storage layer, forming a semiconductor channel layer over the tunnel dielectric layer, etching the stack to form a back side opening in the stack, removing at least a portion of the first material layers and portions of the blocking dielectric layer.
    Type: Grant
    Filed: May 20, 2014
    Date of Patent: March 24, 2015
    Assignee: Sandisk Technologies Inc.
    Inventors: Henry Chien, Donovan Lee, Vinod R. Purayath, Yuan Zhang, James K. Kai, George Matamis
  • Publication number: 20150072488
    Abstract: A method of making a monolithic three dimensional NAND string, including providing a stack of alternating first material layers and second material layers different from the first material layer over a substrate, the stack comprising at least one opening containing a charge storage material comprising a silicide layer, a tunnel dielectric on the charge storage material in the at least one opening, and a semiconductor channel on the tunnel dielectric in the at least one opening, selectively removing the second material layers without removing the first material layers from the stack and forming control gates between the first material layers.
    Type: Application
    Filed: November 12, 2014
    Publication date: March 12, 2015
    Inventors: Henry Chien, Johann Alsmeier, George Samachisa, Henry Chin, George Matamis, Yuan Zhang, James Kai, Vinod Purayath, Donovan Lee
  • Patent number: 8969153
    Abstract: A method of making a NAND string includes forming a tunnel dielectric over a semiconductor channel, forming a charge storage layer over the tunnel dielectric, forming a blocking dielectric over the charge storage layer, and forming a control gate layer over the blocking dielectric. The method also includes patterning the control gate layer to form a plurality of control gates separated by trenches, and reacting a first material with exposed sidewalls of the plurality of control gates to form self aligned metal-first material compound sidewall spacers on the exposed sidewalls of the plurality of control gates.
    Type: Grant
    Filed: July 1, 2013
    Date of Patent: March 3, 2015
    Assignee: SanDisk Technologies Inc.
    Inventors: Donovan Lee, Vinod Purayath, James Kai, George Matamis