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).

  • Publication number: 20180040625
    Abstract: Methods of integrating complementary SONOS devices into a CMOS process flow are described. The method begins with depositing and patterning a first photoresist mask over a surface of a substrate to expose a N-SONOS region, and implanting a channel for a NSONOS device through a first pad oxide, followed by depositing and patterning a second photoresist mask to expose a P-SONOS region, and implanting a channel for a PSONOS device through a second pad oxide. Next, a number of Nwells are concurrently implanted for the PSONOS device and a PMOS device in a core region of the substrate. Finally, the first and second pad oxides, which were left in place to separate the P-SONOS region and the N-SONOS region from the first and second photoresist masks, are concurrently removed. In one embodiment, implanting the Nwells includes implanting a single, contiguous deep Nwell for the PSONOS and PMOS device.
    Type: Application
    Filed: September 18, 2017
    Publication date: February 8, 2018
    Inventors: Venkatraman Prabhakar, Krishnaswamy Ramkumar, Igor Kouznetsov
  • Patent number: 9876020
    Abstract: Memory cells including embedded SONOS based non-volatile memory (NVM) and MOS transistors are described. The memory cell includes a substrate having a non-volatile memory (NVM) region and a plurality of metal-oxide-semiconductor (MOS) regions. A NVM transistor in the NVM region includes a tunnel dielectric on the substrate, a charge-trapping layer on the tunnel dielectric, and a blocking dielectric comprising a high-k dielectric material over the charge-trapping layer. The plurality of MOS regions include a number of MOS transistors. At least one of the MOS transistors includes a gate dielectric comprising a high-k dielectric material over a surface of the substrate. Generally, the blocking dielectric and the gate dielectric comprise the same high-k dielectric material. Other embodiments are also described.
    Type: Grant
    Filed: October 17, 2014
    Date of Patent: January 23, 2018
    Assignee: Cypress Semiconductor Corporation
    Inventor: Krishnaswamy Ramkumar
  • Patent number: 9865711
    Abstract: A method of forming a transistor is described. In one embodiment the method includes: forming a channel of a transistor in a surface of a substrate; forming a dielectric stack including a first oxide layer overlying the surface of the substrate, a middle layer comprising nitride overlying the first oxide layer and a second oxide layer overlying the middle layer; forming over the dielectric stack a mask exposing source and drain (S/D) regions of the transistor; etching the dielectric stack through the mask to thin the dielectric stack by removing the second oxide layer and at least a first portion of the middle layer in S/D regions of the transistor; and implanting dopants into S/D regions of the transistor through the thinned dielectric stack to form a lightly-doped drain (LDD) adjacent to the channel of the transistor. Other embodiments are also described.
    Type: Grant
    Filed: December 19, 2014
    Date of Patent: January 9, 2018
    Assignee: Cypress Semiconductor Corporation
    Inventors: Krishnaswamy Ramkumar, Venkatraman Prabhakar
  • Publication number: 20170352732
    Abstract: A memory is described. Generally, the memory includes a number of non-planar multigate transistors, each including a channel of semiconducting material overlying a surface of a substrate and electrically connecting a source and a drain, a tunnel dielectric layer overlying the channel on at least three sides thereof, and a multi-layer charge-trapping region overlying the tunnel dielectric layer. In one embodiment, the multi-layer charge-trapping region includes a first deuterated layer overlying the tunnel dielectric layer and a first nitride-containing layer overlying the first deuterated layer. Other embodiments are also described.
    Type: Application
    Filed: July 18, 2017
    Publication date: December 7, 2017
    Applicant: Cypress Semiconductor Corporation
    Inventors: Sagy Levy, Fredrick Jenne, Krishnaswamy Ramkumar
  • Patent number: 9824895
    Abstract: A method of integrating a silicon-oxide-nitride-oxide-silicon (SONOS) transistor into a complementary metal-oxide-silicon (CMOS) baseline process. The method includes the steps of forming the gate oxide layer of at least one metal-oxide-silicon (MOS) transistor prior to forming a non-volatile (NV) gate stack of the SONOS transistor.
    Type: Grant
    Filed: December 6, 2016
    Date of Patent: November 21, 2017
    Assignee: Cypress Semiconductor Corporation
    Inventor: Krishnaswamy Ramkumar
  • Patent number: 9793125
    Abstract: A semiconductor device includes a polysilicon substrate, a first oxide layer formed on the polysilicon substrate, an oxygen-rich nitride layer formed on the first oxide layer, a second oxide layer formed on the oxygen-rich nitride layer, and an oxygen-poor nitride layer formed on the second oxide layer.
    Type: Grant
    Filed: August 11, 2015
    Date of Patent: October 17, 2017
    Assignee: CYPRESS SEMICONDUCTOR CORPORATION
    Inventors: Fredrick B. Jenne, Krishnaswamy Ramkumar
  • Patent number: 9793284
    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 16, 2015
    Date of Patent: October 17, 2017
    Assignee: Cypress Semiconductor Corporation
    Inventor: Krishnaswamy Ramkumar
  • Publication number: 20170278853
    Abstract: Memory cells including embedded SONOS based non-volatile memory (NVM) and MOS transistors and methods of forming the same are described. Generally, the method includes: forming a gate stack of a NVM transistor in a NVM region of a substrate including the NVM region and a plurality of MOS regions; and depositing a high-k dielectric material over the gate stack of the NVM transistor and the plurality of MOS regions to concurrently form a blocking dielectric comprising the high-k dielectric material in the gate stack of the NVM transistor and high-k gate dielectrics in the plurality of MOS regions. In one embodiment, a first metal layer is deposited over the high-k dielectric material and patterned to concurrently form a metal gate over the gate stack of the NVM transistor, and a metal gate of a field effect transistor in one of the MOS regions.
    Type: Application
    Filed: March 15, 2017
    Publication date: September 28, 2017
    Applicant: Cypress Semiconductor Corporation
    Inventor: Krishnaswamy Ramkumar
  • Publication number: 20170263623
    Abstract: A 3-D/vertical non-volatile (NV) memory device such as 3-D NAND flash memory and fabrication method thereof, the NV memory device includes vertical openings disposed in a stack of alternating stack layers of first stack layers and second stack layers over a wafer, a multi-layer dielectric disposed over an inner sidewall of each opening, a first channel layer disposed over the multi-layer dielectric, and a second channel layer disposed over the first channel layer, in which at least one of the first or second channel layers includes polycrystalline germanium or silicon-germanium.
    Type: Application
    Filed: March 23, 2016
    Publication date: September 14, 2017
    Inventors: Renhua Zhang, Lei Xue, Rinji Sugino, Krishnaswamy Ramkumar
  • Publication number: 20170263622
    Abstract: Memory devices and methods for forming the same are disclosed. In one embodiment, the device includes a non-volatile memory (NVM) transistor formed in a first region of a substrate, the NVM transistor comprising a channel and a gate stack on the substrate overlying the channel. The gate stack includes a dielectric layer on the substrate, a charge-trapping layer on the dielectric layer, an oxide layer overlying the charge-trapping layer, a first gate overlying the oxide layer, and a first silicide region overlying the first gate. The device includes a metal-oxide-semiconductor transistor formed in a second region of the substrate comprising a gate oxide overlying the substrate in the second region, a second gate overlying the gate oxide, and second silicide region overlying the second gate. A strain inducing structure overlies at least the NVM transistor and a surface of the substrate in the first region of the substrate.
    Type: Application
    Filed: March 6, 2017
    Publication date: September 14, 2017
    Applicant: Cypress Semiconductor Corporation
    Inventors: Krishnaswamy Ramkumar, Igor G. Kouznetsov, Venkatraman Prabhakar
  • Patent number: 9748103
    Abstract: A semiconductor device includes a polysilicon substrate, a first oxide layer formed on the polysilicon substrate, an oxygen-rich nitride layer formed on the first oxide layer, a second oxide layer formed on the oxygen-rich nitride layer, and an oxygen-poor nitride layer formed on the second oxide layer.
    Type: Grant
    Filed: August 11, 2015
    Date of Patent: August 29, 2017
    Assignee: CYPRESS SEMICONDUCTOR CORPORATION
    Inventors: Fredrick B. Jenne, Krishnaswamy Ramkumar
  • Patent number: 9741803
    Abstract: A charge trap memory device is provided. In one embodiment, the charge trap memory device includes a semiconductor material structure having a vertical channel extending from a first diffusion region formed in a semiconducting material to a second diffusion region formed over the first diffusion region, the vertical channel electrically connecting the first diffusion region to the second diffusion region. A tunnel dielectric layer is disposed on the vertical channel, a multi-layer charge-trapping region including a first deuterated layer disposed on the tunnel dielectric layer, a first nitride layer disposed on the first deuterated layer, and a second nitride layer comprising a deuterium-free trap-dense, oxygen-lean nitride disposed on the first nitride layer. The second nitride layer includes a majority of charge traps distributed in the multi-layer charge-trapping region.
    Type: Grant
    Filed: June 22, 2016
    Date of Patent: August 22, 2017
    Assignee: Cypress Semiconductor Corporation
    Inventors: Sagy Levy, Fredrick Jenne, Krishnaswamy Ramkumar
  • Patent number: 9721962
    Abstract: Memory cells including embedded SONOS based non-volatile memory (NVM) and MOS transistors and methods of forming the same are described. Generally, the method includes: forming a gate stack of a NVM transistor in a NVM region of a substrate including the NVM region and a plurality of MOS regions; and depositing a high-k dielectric material over the gate stack of the NVM transistor and the plurality of MOS regions to concurrently form a blocking dielectric comprising the high-k dielectric material in the gate stack of the NVM transistor and high-k gate dielectrics in the plurality of MOS regions. In one embodiment, a first metal layer is deposited over the high-k dielectric material and patterned to concurrently form a metal gate over the gate stack of the NVM transistor, and a metal gate of a field effect transistor in one of the MOS regions.
    Type: Grant
    Filed: March 25, 2016
    Date of Patent: August 1, 2017
    Assignee: Cypress Semiconductor Corporation
    Inventor: Krishnaswamy Ramkumar
  • Patent number: 9716153
    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. The multi-layer charge-trapping region includes a first deuterated layer disposed on the tunnel dielectric layer, a first nitride layer disposed on the first deuterated layer and a second nitride layer.
    Type: Grant
    Filed: July 1, 2012
    Date of Patent: July 25, 2017
    Assignee: Cypress Semiconductor Corporation
    Inventors: Sagy Levy, Fredrick Jenne, Krishnaswamy Ramkumar
  • Publication number: 20170186883
    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: December 12, 2016
    Publication date: June 29, 2017
    Applicant: Cypress Semiconductor Corporation
    Inventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Patent number: 9673211
    Abstract: Memory cells including embedded SONOS based non-volatile memory (NVM) and MOS transistors and methods of forming the same are described. Generally, the method includes: forming a gate stack of a NVM transistor in a NVM region of a substrate including the NVM region and a plurality of MOS regions; and depositing a high-k dielectric material over the gate stack of the NVM transistor and the plurality of MOS regions to concurrently form a blocking dielectric comprising the high-k dielectric material in the gate stack of the NVM transistor and high-k gate dielectrics in the plurality of MOS regions. In one embodiment, a first metal layer is deposited over the high-k dielectric material and patterned to concurrently form a metal gate over the gate stack of the NVM transistor, and a metal gate of a field effect transistor in one of the MOS regions.
    Type: Grant
    Filed: March 25, 2016
    Date of Patent: June 6, 2017
    Assignee: Cypress Semiconductor Corporation
    Inventor: Krishnaswamy Ramkumar
  • Patent number: 9620516
    Abstract: Memory devices and methods for forming the same are disclosed. In one embodiment, the device includes a non-volatile memory (NVM) transistor formed in a first region of a substrate, the NVM transistor comprising a channel and a gate stack on the substrate overlying the channel. The gate stack includes a dielectric layer on the substrate, a charge-trapping layer on the dielectric layer, an oxide layer overlying the charge-trapping layer, a first gate overlying the oxide layer, and a first silicide region overlying the first gate. The device includes a metal-oxide-semiconductor transistor formed in a second region of the substrate comprising a gate oxide overlying the substrate in the second region, a second gate overlying the gate oxide, and a second silicide region overlying the second gate. A strain inducing structure overlies at least the NVM transistor and a surface of the substrate in the first region of the substrate.
    Type: Grant
    Filed: May 4, 2016
    Date of Patent: April 11, 2017
    Assignee: Cypress Semiconductor Corporation
    Inventors: Krishnaswamy Ramkumar, Igor G. Kouznetsov, Venkatraman Prabhakar
  • Publication number: 20170092781
    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: Application
    Filed: August 30, 2016
    Publication date: March 30, 2017
    Inventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Publication number: 20170092729
    Abstract: A semiconductor devices including non-volatile memories and methods of fabricating the same to improve performance thereof are provided. Generally, the device includes a memory transistor comprising a polysilicon channel region electrically connecting a source region and a drain region formed in a substrate, an oxide-nitride-nitride-oxide (ONNO) stack disposed above the channel region, and a high work function gate electrode formed over a surface of the ONNO stack. In one embodiment the ONNO stack includes a multi-layer charge-trapping region including an oxygen-rich first nitride layer and an oxygen-lean second nitride layer disposed above the first nitride layer. Other embodiments are also disclosed.
    Type: Application
    Filed: October 26, 2016
    Publication date: March 30, 2017
    Inventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
  • Publication number: 20170084465
    Abstract: A method of fabricating a memory device is described. Generally, the method includes forming a channel from a semiconducting material overlying a surface of a substrate, and forming dielectric stack on the channel. A first cap layer is formed over the dielectric stack, and a second cap layer including a nitride formed over the first cap layer. The first and second cap layers and the dielectric stack are then patterned to form a gate stack of a device. The second cap layer is removed and an oxidation process performed to form a blocking oxide over the dielectric stack, wherein the oxidation process consumes the first cap layer. Other embodiments are also described.
    Type: Application
    Filed: October 26, 2016
    Publication date: March 23, 2017
    Inventors: Krishnaswamy Ramkumar, Hui-Mei Shih