Patents by Inventor Freidoon Mehrad

Freidoon Mehrad 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: 9035399
    Abstract: A method of simultaneously siliciding a polysilicon gate and source/drain of a semiconductor device, and related device. At least some of the illustrative embodiments are methods comprising forming a gate stack over a semiconductor substrate (the gate stack comprising a first polysilicon layer, a first nitride layer, and a second polysilicon layer), forming a second nitride layer over an active region in the semiconductor substrate adjacent to the gate stack, performing a chemical mechanical polishing that stops on the first nitride layer and on the second nitride layer, removing the first nitride layer and the second nitride layer, and performing a simultaneous silicidation of the first polysilicon layer and the active region.
    Type: Grant
    Filed: March 25, 2010
    Date of Patent: May 19, 2015
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Joe G. Tran
  • Patent number: 8574980
    Abstract: A method of forming fully silicided NMOS and PMOS semiconductor devices having independent polysilicon gate thicknesses, and related device. At least some of the illustrative embodiments are methods comprising forming an N-type gate over a semiconductor substrate (the N-type gate having a first thickness), forming a P-type gate over the semiconductor substrate (the P-type gate having a second thickness different than the first thickness), and performing a simultaneous silicidation of the N-type gate and the P-type gate.
    Type: Grant
    Filed: April 27, 2007
    Date of Patent: November 5, 2013
    Assignee: Texas Instruments Incorporated
    Inventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Craig H. Huffman
  • Patent number: 8372703
    Abstract: A method for fabricating a CMOS integrated circuit (IC) and ICs therefrom includes the steps of providing a substrate having a semiconductor surface, wherein the semiconductor surface has PMOS regions for PMOS devices and NMOS regions for NMOS devices. A gate dielectric layer is formed on the PMOS regions and NMOS regions. An original gate electrode layer is formed on the gate dielectric layer. A gate masking layer is applied on the gate electrode layer. Etching is used to pattern the original gate electrode layer to simultaneously form original gate electrodes for the PMOS devices and NMOS devices. Source and drain regions are formed for the PMOS devices and NMOS devices. The original gate electrodes are removed for at least one of the PMOS devices and NMOS devices to form trenches using an etch process, such as a hydroxide-based solution, wherein at least a portion and generally substantially all of the gate dielectric layer is preserved.
    Type: Grant
    Filed: October 20, 2010
    Date of Patent: February 12, 2013
    Assignee: Texas Instruments Incorporated
    Inventors: Brian K. Kirkpatrick, Freidoon Mehrad, Shaofeng Yu
  • Patent number: 8273645
    Abstract: A method of forming fully silicided (FUSI) gates in MOS transistors which is compatible with wet etch processes used in source/drain silicide formation is disclosed. The gate silicide formation step produces a top layer of metal rich silicide which is resistant to removal in wet etch processes. A blocking layer over active areas prevents source/drain silicide formation during gate silicide formation. Wet etches during removal of the blocking layer and source/drain metal strip do not remove the metal rich gate silicide layer. Anneal of the gate silicide to produce a FUSI gate with a desired stoichiometry is delayed until after formation of the source/drain silicide. The disclosed method is compatible with nickel and nickel-platinum silicide processes.
    Type: Grant
    Filed: August 7, 2009
    Date of Patent: September 25, 2012
    Assignee: Texas Instruments Incorporated
    Inventors: Mark Robert Visokay, Freidoon Mehrad, Richard L. Guldi, Yaw Samuel Obeng
  • Patent number: 7960280
    Abstract: An improved method of forming a fully silicided (FUSI) gate in both NMOS and PMOS transistors of the same MOS device is disclosed. In one example, the method comprises forming a first silicide in at least a top portion of a gate electrode of the PMOS devices and not over the NMOS devices. The method further comprises concurrently forming a second silicide in at least a top portion of a gate electrode of both the NMOS and PMOS devices, and forming a FUSI gate silicide of the gate electrodes. In one embodiment, the thickness of the second silicide is greater than the first silicide by an amount which compensates for a difference in the rates of silicide formation between the NMOS and PMOS devices.
    Type: Grant
    Filed: August 24, 2007
    Date of Patent: June 14, 2011
    Assignee: Texas Instruments Incorporated
    Inventors: Freidoon Mehrad, Frank S. Johnson
  • Patent number: 7943456
    Abstract: A method for fabricating a CMOS integrated circuit (IC) and ICs therefrom includes providing a substrate having a semiconductor surface including PMOS regions for PMOS devices and NMOS regions for NMOS devices. A gate stack including a gate electrode layer is formed on a gate dielectric layer in or on both the PMOS regions and the NMOS regions. An n-type doping is used to create n-type wet etch sensitized regions on opposing sides of the gate stack in both the PMOS and said NMOS regions. Wet etching removes the n-type wet etch sensitized regions in (i) at least a portion of said PMOS regions to form a plurality of PMOS source/drain recesses or (ii) in at least a portion of said NMOS regions to form a plurality of NMOS source/drain recesses, or (i) and (ii). At least one of a compressive strain inducing epitaxial layer is formed in the plurality of PMOS source/drain recesses and a tensile strain inducing epitaxial layer is formed in the plurality of NMOS source/drain recesses.
    Type: Grant
    Filed: December 31, 2008
    Date of Patent: May 17, 2011
    Assignee: Texas Instruments Incorporated
    Inventors: Shaofeng Yu, Freidoon Mehrad, Brian K. Kirkpatrick
  • Publication number: 20110097884
    Abstract: A method of forming fully silicided (FUSI) gates in MOS transistors which is compatible with wet etch processes used in source/drain silicide formation is disclosed. The gate silicide formation step produces a top layer of metal rich silicide which is resistant to removal in wet etch processes. A blocking layer over active areas prevents source/drain silicide formation during gate silicide formation. Wet etches during removal of the blocking layer and source/drain metal strip do not remove the metal rich gate silicide layer. Anneal of the gate silicide to produce a FUSI gate with a desired stoichiometry is delayed until after formation of the source/drain silicide. The disclosed method is compatible with nickel and nickel-platinum silicide processes.
    Type: Application
    Filed: August 7, 2009
    Publication date: April 28, 2011
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Mark Robert VISOKAY, Freidoon MEHRAD, Richard L. GULDI, Yaw Samuel OBENG
  • Patent number: 7910422
    Abstract: A method of forming an integrated circuit having an NMOS transistor and a PMOS transistor is disclosed. The method includes performing pre-gate processing in a NMOS region and a PMOS region over and/or in a semiconductor body, and depositing a polysilicon layer over the semiconductor body in both the NMOS and PMOS regions. The method further includes performing a first type implant into the polysilicon layer in one of the NMOS region and PMOS region, and performing an amorphizing implant into the polysilicon layer in both the NMOS and PMOS regions, thereby converting the polysilicon layer into an amorphous silicon layer. The method further includes patterning the amorphous silicon layer to form gate electrodes, wherein a gate electrode resides in both the NMOS and PMOS regions.
    Type: Grant
    Filed: September 30, 2008
    Date of Patent: March 22, 2011
    Assignee: Texas Instruments Incorporated
    Inventors: Freidoon Mehrad, Jinhan Choi, Frank Scott Johnson
  • Patent number: 7892906
    Abstract: A method for making CMOS transistors that includes forming a NMOS transistor and a PMOS transistor having an undoped polysilicon gate electrode and a hardmask. The method also includes forming a layer of insulating material and then removing the hardmasks and a portion of the layer of insulating material. A layer of silicidation metal is formed and a first silicide anneal changes the undoped polysilicon gate electrodes into partially silicided gate electrodes. Dopants of a first type and a second type are implanted into the partially silicided gate electrode of the PMOS and NMOS transistors and a second silicide anneal is performed to change the doped partially silicided gate electrodes into fully silicided gate electrodes.
    Type: Grant
    Filed: January 30, 2008
    Date of Patent: February 22, 2011
    Assignee: Texas Instruments Incorporated
    Inventors: Freidoon Mehrad, Frank S. Johnson
  • Publication number: 20110031557
    Abstract: A method for fabricating a CMOS integrated circuit (IC) and ICs therefrom includes the steps of providing a substrate having a semiconductor surface, wherein the semiconductor surface has PMOS regions for PMOS devices and NMOS regions for NMOS devices. A gate dielectric layer is formed on the PMOS regions and NMOS regions. An original gate electrode layer is formed on the gate dielectric layer. A gate masking layer is applied on the gate electrode layer. Etching is used to pattern the original gate electrode layer to simultaneously form original gate electrodes for the PMOS devices and NMOS devices. Source and drain regions are formed for the PMOS devices and NMOS devices. The original gate electrodes are removed for at least one of the PMOS devices and NMOS devices to form trenches using an etch process, such as a hydroxide-based solution, wherein at least a portion and generally substantially all of the gate dielectric layer is preserved.
    Type: Application
    Filed: October 20, 2010
    Publication date: February 10, 2011
    Applicant: Texas Instruments Incorporated
    Inventors: Brian K. Kirkpatrick, Freidoon Mehrad, Shaofeng Yu
  • Patent number: 7838356
    Abstract: A method for fabricating a CMOS integrated circuit (IC) and ICs therefrom includes the steps of providing a substrate having a semiconductor surface, wherein the semiconductor surface has PMOS regions for PMOS devices and NMOS regions for NMOS devices. A gate dielectric layer is formed on the PMOS regions and NMOS regions. An original gate electrode layer is formed on the gate dielectric layer. A gate masking layer is applied on the gate electrode layer. Etching is used to pattern the original gate electrode layer to simultaneously form original gate electrodes for the PMOS devices and NMOS devices. Source and drain regions are formed for the PMOS devices and NMOS devices. The original gate electrodes are removed for at least one of the PMOS devices and NMOS devices to form trenches using an etch process, such as a hydroxide-based solution, wherein at least a portion and generally substantially all of the gate dielectric layer is preserved.
    Type: Grant
    Filed: December 31, 2008
    Date of Patent: November 23, 2010
    Assignee: Texas Instruments Incorporated
    Inventors: Brian K. Kirkpatrick, Freidoon Mehrad, Shaofeng Yu
  • Patent number: 7763540
    Abstract: A method for fabricating a semiconductor device includes forming a silicided gate utilizing a CMP stack. The CMP stack includes a first liner formed over the underlying semiconductor device and a first dielectric layer formed over the first liner layer. The first dielectric layer is formed to approximately the height of the gate. A second liner layer is formed over the first dielectric layer. Since the first dielectric layer is formed to approximately the height of the gate, the second liner over the moat regions is at approximately the height of the first liner over the gate. A CMP process is performed to expose the first liner over the top of the gate. Since the first dielectric layer is formed to the height of the gate, a portion of the second liner remains over the moat regions after the CMP process. Afterwards, the gate is exposed and a silicidation is performed to create a silicided gate.
    Type: Grant
    Filed: April 27, 2007
    Date of Patent: July 27, 2010
    Assignee: Texas Instruments Incorporated
    Inventors: Frank Scott Johnson, Freidoon Mehrad
  • Publication number: 20100176462
    Abstract: A method of simultaneously siliciding a polysilicon gate and source/drain of a semiconductor device, and related device. At least some of the illustrative embodiments are methods comprising forming a gate stack over a semiconductor substrate (the gate stack comprising a first polysilicon layer, a first nitride layer, and a second polysilicon layer), forming a second nitride layer over an active region in the semiconductor substrate adjacent to the gate stack, performing a chemical mechanical polishing that stops on the first nitride layer and on the second nitride layer, removing the first nitride layer and the second nitride layer, and performing a simultaneous silicidation of the first polysilicon layer and the active region.
    Type: Application
    Filed: March 25, 2010
    Publication date: July 15, 2010
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Joe G. Tran
  • Publication number: 20100164005
    Abstract: A method for fabricating a CMOS integrated circuit (IC) and ICs therefrom includes providing a substrate having a semiconductor surface including PMOS regions for PMOS devices and NMOS regions for NMOS devices. A gate stack including a gate electrode layer is formed on a gate dielectric layer in or on both the PMOS regions and the NMOS regions. An n-type doping is used to create n-type wet etch sensitized regions on opposing sides of the gate stack in both the PMOS and said NMOS regions. Wet etching removes the n-type wet etch sensitized regions in (i) at least a portion of said PMOS regions to form a plurality of PMOS source/drain recesses or (ii) in at least a portion of said NMOS regions to form a plurality of NMOS source/drain recesses, or (i) and (ii). At least one of a compressive strain inducing epitaxial layer is formed in the plurality of PMOS source/drain recesses and a tensile strain inducing epitaxial layer is formed in the plurality of NMOS source/drain recesses.
    Type: Application
    Filed: December 31, 2008
    Publication date: July 1, 2010
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: SHAOFENG YU, FREIDOON MEHRAD, BRIAN K. KIRKPATRICK
  • Publication number: 20100164008
    Abstract: Semiconductor devices and fabrication methods are provided, in which metal transistor replacement gates are provided for CMOS transistors. The process provides dual or differentiated work function capability (e.g., for PMOS and NMOS transistors) in CMOS processes.
    Type: Application
    Filed: December 24, 2009
    Publication date: July 1, 2010
    Applicant: Texas Instruments Incorporated
    Inventors: Freidoon Mehrad, James J. Chambers, Shaofeng Yu
  • Publication number: 20100164006
    Abstract: A method for fabricating a CMOS integrated circuit (IC) and ICs therefrom includes the steps of providing a substrate having a semiconductor surface, wherein the semiconductor surface has PMOS regions for PMOS devices and NMOS regions for NMOS devices. A gate dielectric layer is formed on the PMOS regions and NMOS regions. An original gate electrode layer is formed on the gate dielectric layer. A gate masking layer is applied on the gate electrode layer. Etching is used to pattern the original gate electrode layer to simultaneously form original gate electrodes for the PMOS devices and NMOS devices. Source and drain regions are formed for the PMOS devices and NMOS devices. The original gate electrodes are removed for at least one of the PMOS devices and NMOS devices to form trenches using an etch process, such as a hydroxide-based solution, wherein at least a portion and generally substantially all of the gate dielectric layer is preserved.
    Type: Application
    Filed: December 31, 2008
    Publication date: July 1, 2010
    Applicant: TEXAS INSTRUMENTS INC
    Inventors: BRIAN K. KIRKPATRICK, Freidoon Mehrad, Shaofeng Yu
  • Patent number: 7727842
    Abstract: A method of simultaneously siliciding a polysilicon gate and source/drain of a semiconductor device, and related device. At least some of the illustrative embodiments are methods comprising forming a gate stack over a semiconductor substrate (the gate stack comprising a first polysilicon layer, a first nitride layer, and a second polysilicon layer), forming a second nitride layer over an active region in the semiconductor substrate adjacent to the gate stack, performing a chemical mechanical polishing that stops on the first nitride layer and on the second nitride layer, removing the first nitride layer and the second nitride layer, and performing a simultaneous silicidation of the first polysilicon layer and the active region.
    Type: Grant
    Filed: April 27, 2007
    Date of Patent: June 1, 2010
    Assignee: Texas Instruments Incorporated
    Inventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Joe G. Tran
  • Patent number: 7670952
    Abstract: A method of manufacturing a semiconductor device, comprising forming a metal silicide gate electrode on a semiconductor substrate surface. The method also comprises exposing the metal silicide gate electrode and the substrate surface to a cleaning process. The cleaning process includes a dry plasma etch using an anhydrous fluoride-containing feed gas and a thermal sublimation configured to leave the metal silicide gate electrode substantially unaltered. The method also comprises depositing a metal layer on source and drain regions of the substrate surface and annealing the metal layer and the source and drain regions of the substrate surface to form metal silicide source and drain contacts.
    Type: Grant
    Filed: March 23, 2007
    Date of Patent: March 2, 2010
    Assignee: Texas Instruments Incorporated
    Inventors: Yaw S. Obeng, Juanita DeLoach, Freidoon Mehrad
  • Publication number: 20090321846
    Abstract: A method of forming fully silicided NMOS and PMOS semiconductor devices having independent polysilicon gate thicknesses, and related device. At least some of the illustrative embodiments are methods comprising forming an N-type gate over a semiconductor substrate (the N-type gate having a first thickness), forming a P-type gate over the semiconductor substrate (the P-type gate having a second thickness different than the first thickness), and performing a simultaneous silicidation of the N-type gate and the P-type gate.
    Type: Application
    Filed: September 8, 2009
    Publication date: December 31, 2009
    Applicant: Texas Instruments Incorporated
    Inventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Craig H. Huffman
  • Patent number: 7601575
    Abstract: The present invention facilitates semiconductor device operation and fabrication by providing a cap-annealing process that improves channel electron mobility without substantially degrading PMOS transistor devices. The process uses an oxide/nitride composite cap to alter the active dopant profile across the channel regions. During an annealing process, dopants migrate out of the Si/SiO2 in a channel region thereby altering the dopant profile of the channel region. This altered profile generally improves channel mobility thereby improving transistor performance and permitting smaller density designs.
    Type: Grant
    Filed: March 4, 2005
    Date of Patent: October 13, 2009
    Assignee: Texas Instruments Incorporated
    Inventors: Haowen Bu, Shashank Ekbote, Rajesh Khamankar, Shaoping Tang, Freidoon Mehrad