Patents by Inventor Krishnaswamy Ramkumar

Krishnaswamy Ramkumar 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: 10784356
    Abstract: A method to integrate silicon-oxide-nitride-oxide-silicon (SONOS) transistors into a complementary metal-oxide-semiconductor (CMOS) flow including a triple gate oxide structure. The memory device may include a non-volatile memory (NVM) transistor that has a charge-trapping layer and a blocking dielectric, a first field-effect transistor (FET) including a first gate oxide of a first thickness, a second FET including a second gate oxide of a second thickness, a third FET including a third gate oxide of a third thickness, in which the first thickness is greater than the second thickness and the second thickness is greater than the third thickness.
    Type: Grant
    Filed: August 8, 2018
    Date of Patent: September 22, 2020
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Krishnaswamy Ramkumar, Igor Kouznetsov, Venkatraman Prabhakar, Ali Keshavarzi
  • Patent number: 10784277
    Abstract: A memory device that includes a non-volatile memory (NVM) transistor disposed in a first region of a substrate. The NVM transistor includes a first gate including a first type of conductor material. The memory device further includes a first type of low voltage field-effect transistor (LV FET) and an input/out field-effect transistor (I/O FET) disposed in a second region of the substrate. The LV FET includes a second gate comprising a second type of conductor material, the I/O FET includes a third gate comprising a second type of conductor material, and the first and second conductor materials are different. Other embodiments are also described.
    Type: Grant
    Filed: January 4, 2018
    Date of Patent: September 22, 2020
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventor: Krishnaswamy Ramkumar
  • Publication number: 20200287056
    Abstract: A method for fabricating a nonvolatile charge trap memory device is described. The method includes subjecting a substrate to a first oxidation process to form a tunnel oxide layer overlying a polysilicon channel, and forming over the tunnel oxide layer a multi-layer charge storing layer comprising an oxygen-rich, first layer comprising a nitride, and an oxygen-lean, second layer comprising a nitride on the first layer. The substrate is then subjected to a second oxidation process to consume a portion of the second layer and form a high-temperature-oxide (HTO) layer overlying the multi-layer charge storing layer. The stoichiometric composition of the first layer results in it being substantially trap free, and the stoichiometric composition of the second layer results in it being trap dense. The second oxidation process can comprise a plasma oxidation process or a radical oxidation process using In-Situ Steam Generation.
    Type: Application
    Filed: March 16, 2020
    Publication date: September 10, 2020
    Inventors: Krishnaswamy Ramkumar, Sagy Levy, Jeong Soo Byun
  • Patent number: 10700083
    Abstract: An embodiment of a method of integration of a non-volatile memory device into a logic MOS flow is described. Generally, the method includes: forming a pad dielectric layer of a MOS device above a first region of a substrate; forming a channel of the memory device from a thin film of semiconducting material overlying a surface above a second region of the substrate, the channel connecting a source and drain of the memory device; forming a patterned dielectric stack overlying the channel above the second region, the patterned dielectric stack comprising a tunnel layer, a charge-trapping layer, and a sacrificial top layer; simultaneously removing the sacrificial top layer from the second region of the substrate, and the pad dielectric layer from the first region of the substrate; and simultaneously forming a gate dielectric layer above the first region of the substrate and a blocking dielectric layer above the charge-trapping layer.
    Type: Grant
    Filed: August 11, 2015
    Date of Patent: June 30, 2020
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Krishnaswamy Ramkumar, Bo Jin, Fredrick B. Jenne
  • Patent number: 10699901
    Abstract: A method of scaling a nonvolatile trapped-charge memory device and the device made thereby is provided. In an embodiment, the method includes forming a channel region including polysilicon electrically connecting a source region and a drain region in a substrate. A tunneling layer is formed on the substrate over the channel region by oxidizing the substrate to form an oxide film and nitridizing the oxide film. A multi-layer charge trapping layer including an oxygen-rich first layer and an oxygen-lean second layer is formed on the tunneling layer, and a blocking layer deposited on the multi-layer charge trapping layer. In one embodiment, the method further includes a dilute wet oxidation to densify a deposited blocking oxide and to oxidize a portion of the oxygen-lean second layer.
    Type: Grant
    Filed: May 24, 2018
    Date of Patent: June 30, 2020
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Frederick B. Jenne, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Publication number: 20200161324
    Abstract: A memory transistor includes a gate electrode and a blocking structure disposed beneath the gate electrode, where the blocking structure is formed by plasma oxidation. The memory transistor includes a multi-layer charge storage layer disposed beneath the blocking structure, wherein the multi-layer charge storage layer includes a trap dense charge storage layer over a substantially trap free charge storage layer, where a thickness of the trap dense charge storage layer is reduced by the plasma oxidation. The memory transistor further includes a tunneling layer disposed beneath the multi-layer charge storage layer and a channel region disposed beneath the tunneling layer, where the channel region is positioned laterally between a source region and a drain region.
    Type: Application
    Filed: June 7, 2019
    Publication date: May 21, 2020
    Inventors: Jeong Soo Byun, Krishnaswamy Ramkumar
  • Publication number: 20200152752
    Abstract: Semiconductor devices including non-volatile memory transistors and methods of fabricating the same to improve performance thereof are provided. In one embodiment, the memory transistor comprises an oxide-nitride-oxide (ONO) stack on a surface of a semiconductor substrate, and a high work function gate electrode formed over a surface of the ONO stack. Preferably, the gate electrode comprises a doped polysilicon layer, and the ONO stack comprises multi-layer charge storing layer including at least a substantially trap free bottom oxynitride layer and a charge trapping top oxynitride layer. More preferably, the device also includes a metal oxide semiconductor (MOS) logic transistor formed on the same substrate, the logic transistor including a gate oxide and a high work function gate electrode. In certain embodiments, the dopant is a P+ dopant and the memory transistor comprises N-type (NMOS) silicon-oxide-nitride-oxide-silicon (SONOS) transistor while the logic transistor a P-type (PMOS) transistor.
    Type: Application
    Filed: October 14, 2019
    Publication date: May 14, 2020
    Inventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Publication number: 20200144399
    Abstract: An embodiment of a semiconductor memory device including a multi-layer charge storing layer and methods of forming the same are described. Generally, the device includes a channel formed from a semiconducting material overlying a surface on a substrate connecting a source and a drain of the memory device; a tunnel oxide layer overlying the channel; and a multi-layer charge storing layer including an oxygen-rich, first oxynitride layer on the tunnel oxide layer in which a stoichiometric composition of the first oxynitride layer results in it being substantially trap free, and an oxygen-lean, second oxynitride layer on the first oxynitride layer in which a stoichiometric composition of the second oxynitride layer results in it being trap dense. In one embodiment, the device comprises a non-planar transistor including a gate having multiple surfaces abutting the channel, and the gate comprises the tunnel oxide layer and the multi-layer charge storing layer.
    Type: Application
    Filed: December 24, 2019
    Publication date: May 7, 2020
    Inventors: Sagy Charel Levy, Krishnaswamy Ramkumar, Fredrick Jenne, Sam G. Geha
  • Publication number: 20200111805
    Abstract: A method of controlling the thickness of gate oxides in an integrated CMOS process which includes performing a two-step gate oxidation process to concurrently oxidize and therefore consume at least a first portion of the cap layer of the NV gate stack to form a blocking oxide and form a gate oxide of at least one metal-oxide-semiconductor (MOS) transistor in the second region, wherein the gate oxide of the at least one MOS transistor is formed during both a first oxidation step and a second oxidation step of the gate oxidation process.
    Type: Application
    Filed: September 16, 2019
    Publication date: April 9, 2020
    Inventor: Krishnaswamy Ramkumar
  • Patent number: 10615289
    Abstract: An embodiment of a nonvolatile charge trap memory device is described. In one embodiment, the device comprises a channel comprising silicon overlying a surface on a substrate electrically connecting a first diffusion region and a second diffusion region of the memory device, and a gate stack intersecting and overlying at least a portion of the channel, the gate stack comprising a tunnel oxide abutting the channel, a split charge-trapping region abutting the tunnel oxide, and a multi-layer blocking dielectric abutting the split charge-trapping region. The split charge-trapping region includes a first charge-trapping layer comprising a nitride closer to the tunnel oxide, and a second charge-trapping layer comprising a nitride overlying the first charge-trapping layer. The multi-layer blocking dielectric comprises at least a high-K dielectric layer.
    Type: Grant
    Filed: August 30, 2016
    Date of Patent: April 7, 2020
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Patent number: 10593812
    Abstract: A method for fabricating a nonvolatile charge trap memory device is described. The method includes subjecting a substrate to a first oxidation process to form a tunnel oxide layer overlying a polysilicon channel, and forming over the tunnel oxide layer a multi-layer charge storing layer comprising an oxygen-rich, first layer comprising a nitride, and an oxygen-lean, second layer comprising a nitride on the first layer. The substrate is then subjected to a second oxidation process to consume a portion of the second layer and form a high-temperature-oxide (HTO) layer overlying the multi-layer charge storing layer. The stoichiometric composition of the first layer results in it being substantially trap free, and the stoichiometric composition of the second layer results in it being trap dense. The second oxidation process can comprise a plasma oxidation process or a radical oxidation process using In-Situ Steam Generation.
    Type: Grant
    Filed: June 5, 2018
    Date of Patent: March 17, 2020
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Krishnaswamy Ramkumar, Sagy Charel Levy, Jeong Soo Byun
  • Publication number: 20200051642
    Abstract: A memory device that includes a non-volatile memory (NVM) array, divided into a flash memory portion and an electrically erasable programmable read-only memory (EEPROM) portion. The NVM array includes charge-trapping memory cells arranged in rows and columns, in which each memory cell has a memory transistor including an angled lightly doped drain (LDD) implant, and a select transistor including a shared source region with a halo implant. The flash memory portion and the EEPROM portion are disposed within one single semiconductor die. Other embodiments are also disclosed.
    Type: Application
    Filed: June 24, 2019
    Publication date: February 13, 2020
    Inventors: Gary Menezes, Krishnaswamy Ramkumar, Ali Keshavarzi, Venkatraman Prabhakar
  • Publication number: 20200020710
    Abstract: A method of fabricating a memory device is described. Generally, the method includes: forming on a surface of a substrate a dielectric stack including a tunneling dielectric and a charge-trapping layer overlying the tunneling dielectric; forming a cap layer overlying the dielectric stack, wherein the cap layer comprises a multi-layer cap layer including at least a first cap layer overlying the charge-trapping layer, and a second cap layer overlying the first cap layer; patterning the cap layer and the dielectric stack to form a gate stack of a memory device; removing the second cap layer; and performing an oxidation process to oxidize the first cap layer to form a blocking oxide overlying the charge-trapping layer, wherein the oxidation process consumes the first cap layer. Other embodiments are also described.
    Type: Application
    Filed: September 23, 2019
    Publication date: January 16, 2020
    Inventor: Krishnaswamy Ramkumar
  • Publication number: 20190371806
    Abstract: Semiconductor devices and methods of manufacturing the same are provided. The semiconductor devices may have a non-volatile memory (NVM) transistor including a charge-trapping layer and a blocking dielectric, a field-effect transistor (FET) of a first type including a first gate dielectric having a first thickness, a FET of a second type including a second gate dielectric having a second thickness, and a FET of a third type including a third gate dielectric having a third thickness. In some embodiments, the first, second, and third gate dielectric includes a high dielectric constant (high-K) dielectric layer, and the first thickness is greater than the second thickness, the second thickness is greater than the third thickness. Other embodiments are also described.
    Type: Application
    Filed: August 15, 2019
    Publication date: December 5, 2019
    Inventor: Krishnaswamy Ramkumar
  • Publication number: 20190319104
    Abstract: Scaling a charge trap memory device and the article made thereby. In one embodiment, the charge trap memory device includes a substrate having a source region, a drain region, and a channel region electrically connecting the source and drain. A tunnel dielectric layer is disposed above the substrate over the channel region, and a multi-layer charge-trapping region disposed on the tunnel dielectric layer.
    Type: Application
    Filed: March 12, 2019
    Publication date: October 17, 2019
    Inventors: Sagy Levy, Fredrick Jenne, Krishnaswamy Ramkumar
  • Patent number: 10446656
    Abstract: Semiconductor devices including non-volatile memory transistors and methods of fabricating the same to improve performance thereof are provided. In one embodiment, the memory transistor comprises an oxide-nitride-oxide (ONO) stack on a surface of a semiconductor substrate, and a high work function gate electrode formed over a surface of the ONO stack. Preferably, the gate electrode comprises a doped polysilicon layer, and the ONO stack comprises multi-layer charge storing layer including at least a substantially trap free bottom oxynitride layer and a charge trapping top oxynitride layer. More preferably, the device also includes a metal oxide semiconductor (MOS) logic transistor formed on the same substrate, the logic transistor including a gate oxide and a high work function gate electrode. In certain embodiments, the dopant is a P+ dopant and the memory transistor comprises N-type (NMOS) silicon-oxide-nitride-oxide-silicon (SONOS) transistor while the logic transistor a P-type (PMOS) transistor.
    Type: Grant
    Filed: December 12, 2016
    Date of Patent: October 15, 2019
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Patent number: 10424592
    Abstract: A method of fabricating a memory device is described. Generally, the method includes: forming on a surface of a substrate a dielectric stack including a tunneling dielectric and a charge-trapping layer overlying the tunneling dielectric; forming a cap layer overlying the dielectric stack, wherein the cap layer comprises a multi-layer cap layer including at least a first cap layer overlying the charge-trapping layer, and a second cap layer overlying the first cap layer; patterning the cap layer and the dielectric stack to form a gate stack of a memory device; removing the second cap layer; and performing an oxidation process to oxidize the first cap layer to form a blocking oxide overlying the charge-trapping layer, wherein the oxidation process consumes the first cap layer. Other embodiments are also described.
    Type: Grant
    Filed: July 24, 2018
    Date of Patent: September 24, 2019
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventor: Krishnaswamy Ramkumar
  • Patent number: 10418373
    Abstract: A method of controlling the thickness of gate oxides in an integrated CMOS process which includes performing a two-step gate oxidation process to concurrently oxidize and therefore consume at least a first portion of the cap layer of the NV gate stack to form a blocking oxide and form a gate oxide of at least one metal-oxide-semiconductor (MOS) transistor in the second region, wherein the gate oxide of the at least one MOS transistor is formed during both a first oxidation step and a second oxidation step of the gate oxidation process.
    Type: Grant
    Filed: November 13, 2018
    Date of Patent: September 17, 2019
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventor: Krishnaswamy Ramkumar
  • Patent number: 10411103
    Abstract: Semiconductor devices including non-volatile memory transistors and methods of fabricating the same to improve performance thereof are provided. In one embodiment, the memory transistor comprises an oxide-nitride-oxide (ONO) stack on a surface of a semiconductor substrate, and a high work function gate electrode formed over a surface of the ONO stack. Preferably, the gate electrode comprises a doped polysilicon layer, and the ONO stack comprises multi-layer charge storing layer including at least a substantially trap free bottom oxynitride layer and a charge trapping top oxynitride layer. More preferably, the device also includes a metal oxide semiconductor (MOS) logic transistor formed on the same substrate, the logic transistor including a gate oxide and a high work function gate electrode. In certain embodiments, the dopant is a P+ dopant and the memory transistor comprises N-type (NMOS) silicon-oxide-nitride-oxide-silicon (SONOS) transistor while the logic transistor a P-type (PMOS) transistor.
    Type: Grant
    Filed: December 12, 2016
    Date of Patent: September 10, 2019
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Patent number: 10374067
    Abstract: An embodiment of a semiconductor memory device including a multi-layer charge storing layer and methods of forming the same are described. Generally, the device includes a channel formed from a semiconducting material overlying a surface on a substrate connecting a source and a drain of the memory device; a tunnel oxide layer overlying the channel; and a multi-layer charge storing layer including an oxygen-rich, first oxynitride layer on the tunnel oxide layer in which a stoichiometric composition of the first oxynitride layer results in it being substantially trap free, and an oxygen-lean, second oxynitride layer on the first oxynitride layer in which a stoichiometric composition of the second oxynitride layer results in it being trap dense. In one embodiment, the device comprises a non-planar transistor including a gate having multiple surfaces abutting the channel, and the gate comprises the tunnel oxide layer and the multi-layer charge storing layer.
    Type: Grant
    Filed: June 22, 2016
    Date of Patent: August 6, 2019
    Assignee: LONGITUDE FLASH MEMORY SOLUTIONS LTD.
    Inventors: Sagy Levy, Krishnaswamy Ramkumar, Fredrick Jenne, Sam Geha