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).
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Patent number: 9035399Abstract: 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: GrantFiled: March 25, 2010Date of Patent: May 19, 2015Assignee: TEXAS INSTRUMENTS INCORPORATEDInventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Joe G. Tran
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Patent number: 8574980Abstract: 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: GrantFiled: April 27, 2007Date of Patent: November 5, 2013Assignee: Texas Instruments IncorporatedInventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Craig H. Huffman
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Patent number: 8372703Abstract: 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: GrantFiled: October 20, 2010Date of Patent: February 12, 2013Assignee: Texas Instruments IncorporatedInventors: Brian K. Kirkpatrick, Freidoon Mehrad, Shaofeng Yu
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Patent number: 8273645Abstract: 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: GrantFiled: August 7, 2009Date of Patent: September 25, 2012Assignee: Texas Instruments IncorporatedInventors: Mark Robert Visokay, Freidoon Mehrad, Richard L. Guldi, Yaw Samuel Obeng
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Patent number: 7960280Abstract: 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: GrantFiled: August 24, 2007Date of Patent: June 14, 2011Assignee: Texas Instruments IncorporatedInventors: Freidoon Mehrad, Frank S. Johnson
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Patent number: 7943456Abstract: 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: GrantFiled: December 31, 2008Date of Patent: May 17, 2011Assignee: Texas Instruments IncorporatedInventors: Shaofeng Yu, Freidoon Mehrad, Brian K. Kirkpatrick
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Publication number: 20110097884Abstract: 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: ApplicationFiled: August 7, 2009Publication date: April 28, 2011Applicant: TEXAS INSTRUMENTS INCORPORATEDInventors: Mark Robert VISOKAY, Freidoon MEHRAD, Richard L. GULDI, Yaw Samuel OBENG
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Patent number: 7910422Abstract: 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: GrantFiled: September 30, 2008Date of Patent: March 22, 2011Assignee: Texas Instruments IncorporatedInventors: Freidoon Mehrad, Jinhan Choi, Frank Scott Johnson
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Patent number: 7892906Abstract: 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: GrantFiled: January 30, 2008Date of Patent: February 22, 2011Assignee: Texas Instruments IncorporatedInventors: Freidoon Mehrad, Frank S. Johnson
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Publication number: 20110031557Abstract: 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: ApplicationFiled: October 20, 2010Publication date: February 10, 2011Applicant: Texas Instruments IncorporatedInventors: Brian K. Kirkpatrick, Freidoon Mehrad, Shaofeng Yu
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Patent number: 7838356Abstract: 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: GrantFiled: December 31, 2008Date of Patent: November 23, 2010Assignee: Texas Instruments IncorporatedInventors: Brian K. Kirkpatrick, Freidoon Mehrad, Shaofeng Yu
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Patent number: 7763540Abstract: 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: GrantFiled: April 27, 2007Date of Patent: July 27, 2010Assignee: Texas Instruments IncorporatedInventors: Frank Scott Johnson, Freidoon Mehrad
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Publication number: 20100176462Abstract: 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: ApplicationFiled: March 25, 2010Publication date: July 15, 2010Applicant: TEXAS INSTRUMENTS INCORPORATEDInventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Joe G. Tran
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Publication number: 20100164005Abstract: 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: ApplicationFiled: December 31, 2008Publication date: July 1, 2010Applicant: TEXAS INSTRUMENTS INCORPORATEDInventors: SHAOFENG YU, FREIDOON MEHRAD, BRIAN K. KIRKPATRICK
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Publication number: 20100164008Abstract: 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: ApplicationFiled: December 24, 2009Publication date: July 1, 2010Applicant: Texas Instruments IncorporatedInventors: Freidoon Mehrad, James J. Chambers, Shaofeng Yu
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Publication number: 20100164006Abstract: 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: ApplicationFiled: December 31, 2008Publication date: July 1, 2010Applicant: TEXAS INSTRUMENTS INCInventors: BRIAN K. KIRKPATRICK, Freidoon Mehrad, Shaofeng Yu
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Patent number: 7727842Abstract: 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: GrantFiled: April 27, 2007Date of Patent: June 1, 2010Assignee: Texas Instruments IncorporatedInventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Joe G. Tran
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Patent number: 7670952Abstract: 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: GrantFiled: March 23, 2007Date of Patent: March 2, 2010Assignee: Texas Instruments IncorporatedInventors: Yaw S. Obeng, Juanita DeLoach, Freidoon Mehrad
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Publication number: 20090321846Abstract: 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: ApplicationFiled: September 8, 2009Publication date: December 31, 2009Applicant: Texas Instruments IncorporatedInventors: Freidoon Mehrad, Shaofeng Yu, Steven A. Vitale, Craig H. Huffman
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Patent number: 7601575Abstract: 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: GrantFiled: March 4, 2005Date of Patent: October 13, 2009Assignee: Texas Instruments IncorporatedInventors: Haowen Bu, Shashank Ekbote, Rajesh Khamankar, Shaoping Tang, Freidoon Mehrad