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).
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Patent number: 9552991Abstract: 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: GrantFiled: April 30, 2014Date of Patent: January 24, 2017Assignee: SANDISK TECHNOLOGIES LLCInventors: Akira Matsudaira, James Kai, Yuan Zhang, Vinod Purayath, Donovan Lee
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Patent number: 9548311Abstract: 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: GrantFiled: April 26, 2016Date of Patent: January 17, 2017Assignee: SanDisk Technologies LLCInventors: Donovan Lee, Vinod R Purayath, James Kai
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Patent number: 9543139Abstract: 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: GrantFiled: April 7, 2014Date of Patent: January 10, 2017Assignee: SANDISK TECHNOLOGIES LLCInventors: Akira Matsudaira, Donovan Lee
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Publication number: 20160240546Abstract: 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: ApplicationFiled: April 26, 2016Publication date: August 18, 2016Applicant: SanDisk Technologies Inc.Inventors: Donovan Lee, Vinod R. Purayath, James Kai
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Patent number: 9349740Abstract: 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: GrantFiled: January 24, 2014Date of Patent: May 24, 2016Assignee: SanDisk Technologies Inc.Inventors: Donovan Lee, Vinod R Purayath, James Kai
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Patent number: 9331181Abstract: 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: GrantFiled: March 11, 2013Date of Patent: May 3, 2016Assignee: SANDISK TECHNOLOGIES INC.Inventors: Donovan Lee, James K. Kai, George Samachisa, Henry Chien, George Matamis, Vinod R. Purayath
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Three dimensional NAND device with birds beak containing floating gates and method of making thereof
Patent number: 9252151Abstract: 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: GrantFiled: February 18, 2014Date of Patent: February 2, 2016Assignee: SANDISK TECHNOLOGIES INC.Inventors: Henry Chien, Donovan Lee, Vinod R. Purayath, Yuan Zhang, James K. Kai, George Matamis -
Patent number: 9230971Abstract: 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: GrantFiled: January 28, 2015Date of Patent: January 5, 2016Assignee: SANDISK TECHNOLOGIES INC.Inventors: Donovan Lee, Vinod Purayath, James Kai, George Matamis
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Patent number: 9224746Abstract: 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: GrantFiled: November 5, 2013Date of Patent: December 29, 2015Assignee: SanDisk Technologies Inc.Inventors: Vinod R. Purayath, James Kai, Donovan Lee, Yuan Zhang, Akira Matsudaira
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Publication number: 20150318295Abstract: 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: ApplicationFiled: April 30, 2014Publication date: November 5, 2015Applicant: SanDisk Technologies, Inc.Inventors: James Kai, Vinod Purayath, Donovan Lee, Akira Matsudaira
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Publication number: 20150318298Abstract: 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: ApplicationFiled: April 30, 2014Publication date: November 5, 2015Applicant: SanDisk Technologies, Inc.Inventors: Akira Matsudaira, James Kai, Yuan Zhang, Vinod Purayath, Donovan Lee
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Patent number: 9177808Abstract: 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: GrantFiled: May 22, 2014Date of Patent: November 3, 2015Assignee: SANDISK TECHNOLOGIES INC.Inventors: Vinod R. Purayath, James Kai, Donovan Lee, Akira Matsudaira, Yuan Zhang
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Patent number: 9165940Abstract: 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: GrantFiled: November 12, 2014Date of Patent: October 20, 2015Assignee: SANDISK TECHNOLOGIES INC.Inventors: Henry Chien, Johann Alsmeier, George Samachisa, Henry Chin, George Matamis, Yuan Zhang, James Kai, Vinod Purayath, Donovan Lee
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Publication number: 20150287733Abstract: 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: ApplicationFiled: April 7, 2014Publication date: October 8, 2015Applicant: SANDISK TECHNOLOGIES INC.Inventors: Akira Matsudaira, Donovan Lee
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Publication number: 20150214235Abstract: 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: ApplicationFiled: January 24, 2014Publication date: July 30, 2015Applicant: SanDisk Technologies Inc.Inventors: Donovan Lee, Vinod R. Purayath, James Kai
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Publication number: 20150137208Abstract: 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: ApplicationFiled: January 28, 2015Publication date: May 21, 2015Inventors: Donovan Lee, Vinod Purayath, James Kai, George Matamis
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Patent number: 8987802Abstract: 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: GrantFiled: February 28, 2013Date of Patent: March 24, 2015Assignee: SanDisk Technologies Inc.Inventors: Donovan Lee, James Kai, Vinod Purayath, George Matamis, Steven J. Radigan
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Three dimensional NAND device with birds beak containing floating gates and method of making thereof
Patent number: 8987087Abstract: 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: GrantFiled: May 20, 2014Date of Patent: March 24, 2015Assignee: Sandisk Technologies Inc.Inventors: Henry Chien, Donovan Lee, Vinod R. Purayath, Yuan Zhang, James K. Kai, George Matamis -
Publication number: 20150072488Abstract: 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: ApplicationFiled: November 12, 2014Publication date: March 12, 2015Inventors: Henry Chien, Johann Alsmeier, George Samachisa, Henry Chin, George Matamis, Yuan Zhang, James Kai, Vinod Purayath, Donovan Lee
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Patent number: 8969153Abstract: 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: GrantFiled: July 1, 2013Date of Patent: March 3, 2015Assignee: SanDisk Technologies Inc.Inventors: Donovan Lee, Vinod Purayath, James Kai, George Matamis