Patents by Inventor Atul C. Ajmera

Atul C. Ajmera 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: 20130256766
    Abstract: Process for enhancing strain in a channel with a stress liner, spacer, process for forming integrated circuit and integrated circuit. A first spacer composed of a first oxide and first nitride layer is applied to a gate electrode on a substrate, and a second spacer composed of a second oxide and second nitride layer is applied. Deep implanting of source and drain in the substrate occurs, and removal of the second nitride, second oxide, and first nitride layers.
    Type: Application
    Filed: May 20, 2013
    Publication date: October 3, 2013
    Applicant: International Business Machines Corporation
    Inventors: Atul C. AJMERA, Christopher V. BAIOCCO, Xiangdong CHEN, Wenzhi GAO, Young W. TEH
  • Patent number: 8461009
    Abstract: Process for enhancing strain in a channel with a stress liner, spacer, process for forming integrated circuit and integrated circuit. A first spacer composed of an first oxide and first nitride layer is applied to a gate electrode on a substrate, and a second spacer composed of a second oxide and second nitride layer is applied. Deep implanting of source and drain in the substrate occurs, and removal of the second nitride, second oxide, and first nitride layers.
    Type: Grant
    Filed: February 28, 2006
    Date of Patent: June 11, 2013
    Assignees: International Business Machines Corporation, Chartered Semiconductor Manufacturing Ltd.
    Inventors: Atul C. Ajmera, Christopher V. Baiocco, Xiangdong Chen, Wenzhi Gao, Young Way Teh
  • Patent number: 7759206
    Abstract: A method of forming a semiconductor device that embeds an L-shaped spacer is provided. The method includes defining an L-shaped spacer on each side of a gate region of a substrate and embedding the L-shaped spacers in an oxide layer so that the oxide layer extends over a portion of the substrate a predetermined distance from a lateral edge of the L-shaped spacer. And removing oxide layers to expose the L-shape spacers.
    Type: Grant
    Filed: November 29, 2005
    Date of Patent: July 20, 2010
    Assignees: International Business Machines Corporation, Chartered Semiconductor Manufacturing Ltd.
    Inventors: Zhijiong Luo, Young Way Teh, Atul C. Ajmera
  • Patent number: 7091128
    Abstract: A method for forming a CMOS device in a manner so as to avoid dielectric layer undercut during a pre-silicide cleaning step is described. During formation of CMOS device comprising a gate stack on a semiconductor substrate surface, the patterned gate stack including gate dielectric below a conductor with vertical sidewalls, a dielectric layer is formed thereover and over the substrate surfaces. Respective nitride spacer elements overlying the dielectric layer are formed at each vertical sidewall. The dielectric layer on the substrate surface is removed using an etch process such that a portion of the dielectric layer underlying each spacer remains. Then, a nitride layer is deposited over the entire sample (the gate stack, the spacer elements at each gate sidewall, and substrate surfaces) and subsequently removed by an etch process such that only a portion of said nitride film (the “plug”) remains.
    Type: Grant
    Filed: November 4, 2005
    Date of Patent: August 15, 2006
    Assignee: International Business Machines Corporation
    Inventors: Atul C. Ajmera, Andres Bryant, Percy V. Gilbert, Michael A. Gribelyuk, Edward P. Maciejewski, Renee T. Mo, Shreesh Narasimha
  • Patent number: 6991979
    Abstract: A method for forming a CMOS device in a manner so as to avoid dielectric layer undercut during a pre-silicide cleaning step is described. During formation of CMOS device comprising a gate stack on a semiconductor substrate surface, the patterned gate stack including gate dielectric below a conductor with vertical sidewalls, a dielectric layer is formed thereover and over the substrate surfaces. Respective nitride spacer elements overlying the dielectric layer are formed at each vertical sidewall. The dielectric layer on the substrate surface is removed using an etch process such that a portion of the dielectric layer underlying each spacer remains. Then, a nitride layer is deposited over the entire sample (the gate stack, the spacer elements at each gate sidewall, and substrate surfaces) and subsequently removed by an etch process such that only a portion of said nitride film (the “plug”) remains.
    Type: Grant
    Filed: September 22, 2003
    Date of Patent: January 31, 2006
    Assignee: International Business Machines Corporation
    Inventors: Atul C. Ajmera, Andres Bryant, Percy V. Gilbert, Michael A Gribelyuk, Edward P. Maciejewski, Renee T. Mo, Shreesh Narasimha
  • Patent number: 6900092
    Abstract: The present invention provides a method of formed a nitrided surface layer atop a polysilicon gate electrode that inhibits the growth of an epi silicon layer thereon. Specifically, the method of the present invention includes the steps of: forming a polysilicon layer atop a gate dielectric layer, forming a nitrided surface layer on the polysilicon layer; selectively removing portions of the nitrided surface layer and the polysilicon layer stopping on the gate dielectric layer, while leaving a patterned stack of the nitrided surface layer and the polysilicon layer on the gate dielectric layer; forming sidewall spacers on at least exposed vertical sidewalls of polysilicon layer; removing portions of the gate dielectric layer not protected by the sidewall spacers; and growing an epi silicon layer on exposed horizontal surfaces of an underlying semiconductor substrate.
    Type: Grant
    Filed: June 27, 2002
    Date of Patent: May 31, 2005
    Assignee: International Business Machines Corporation
    Inventors: Atul C. Ajmera, Dominic J. Schepis, Michael D. Steigerwalt
  • Patent number: 6642156
    Abstract: A method for forming an ultra thin gate dielectric for an integrated circuit device is disclosed. In an exemplary embodiment of the invention, the method includes forming an initial nitride layer upon a substrate by rapidly heating the substrate in the presence of an ammonia (NH3) gas, and then re-oxidizing the initial nitride layer by rapidly heating the initial nitride layer in the presence of a nitric oxide (NO) gas, thereby forming an oxynitride layer. The oxynitride layer has a nitrogen concentration therein of at about 1.0×1015 atoms/cm2 to about 6.0×1015 atoms/cm2, and has a thickness which may be controlled within a sub 10 Å range.
    Type: Grant
    Filed: August 1, 2001
    Date of Patent: November 4, 2003
    Assignee: International Business Machines Corporation
    Inventors: Evgeni Gousev, Atul C. Ajmera, Christopher P. D'Emic
  • Patent number: 6605521
    Abstract: In order to prevent abnormal oxidation of the side wall of a polycide gate conductor layer in the oxidation heat treatment process after the RIE processing of the polycide gate conductor layer in a semiconductor memory cell, the heat treatment for oxidizing the side wall of the polycide gate conductor layer is conducted in two steps with different conditions. By conducting the first heat treatment process in an inert atmosphere, a thin oxide film is formed on the side wall of the polycide tungsten/gate conductor layer. Then by conducting the second heat treatment process in an atmosphere with a strong oxidizing property, a thick oxide film without abnormal oxidation can be formed.
    Type: Grant
    Filed: October 8, 2002
    Date of Patent: August 12, 2003
    Assignees: Kabushiki Kaisha Toshiba, International Business Machines Corporation
    Inventors: Atul C. Ajmera, Karanam Balasubramanyam, Tomio Katata, Shang-Bin Ko
  • Patent number: 6602759
    Abstract: A method for forming an isolation trench in a silicon or silicon-on-insulator substrate is described in which a trench is formed in the semiconductor structure (containing a multiple layer structure of Si, SiO2, and SiN layers) and an undoped polysilicon layer is deposited on the bottom and sidewalls of the trench and on the surface of the region adjacent to the trench. A substantial portion of the trench is left unfilled by the undoped polysilicon layer deposited. The polysilicon layer is thermally oxidized to form a thermal oxide that fills the trench and thereby avoids forming a birds-beak formation of the thermal oxide above the sidewalls of the trench. The isolation structure may be planarized by either removing the polysilicon layer from the region adjacent to the trench before oxidation or later removing the oxide from the SiN layer and adjusting height of the oxide in the trench.
    Type: Grant
    Filed: December 7, 2000
    Date of Patent: August 5, 2003
    Assignee: International Business Machines Corporation
    Inventors: Atul C. Ajmera, Klaus D. Beyer, Dominic J. Schepis
  • Patent number: 6566210
    Abstract: The present invention provides a method of preparing a Si-based metal-insulator-semiconductor (MIS) transistor which prevents the polycrystalline grains of the gate conductor from getting significantly larger by reducing the thermal budget of the sidewall oxidation process. The thermal budget of the inventive sidewall oxidation process is reduced one or two orders of magnitude over conventional prior art sidewall oxidation processes by utilizing atomic oxygen as the oxidizing ambient. The present invention also provides Si-based MIS transistors having a gate conductor having grain sizes of about 0.1, preferably 0.05, &mgr;m or less.
    Type: Grant
    Filed: July 13, 2001
    Date of Patent: May 20, 2003
    Assignee: International Business Machines Corporation
    Inventors: Atul C. Ajmera, Omer H. Dokumaci, Bruce B. Doris, Oleg Gluschenkov
  • Patent number: 6566198
    Abstract: A CMOS structure and method of achieving self-aligned raised source/drain for CMOS structures on SOI without relying on selective epitaxial growth of silicon. In the method, CMOS structures are provided by performing sacrificial oxidation so that oxidation occurs on the surface of both the SOI and BOX interface. This allows for oxide spacer formation for gate-to-source/drain isolation which makes possible raised source/drain fabrication without increasing contact resistance.
    Type: Grant
    Filed: March 29, 2001
    Date of Patent: May 20, 2003
    Assignee: International Business Machines Corporation
    Inventors: Heemyong Park, Fariborz Assaderaghi, Atul C. Ajmera, Ghavam G. Shahidi
  • Publication number: 20030036253
    Abstract: In order to prevent abnormal oxidation of the side wall of a polycide gate conductor layer in the oxidation heat treatment process after the RIE processing of the polycide gate conductor layer in a semiconductor memory cell, the heat treatment for oxidizing the side wall of the polycide gate conductor layer is conducted in two steps with different conditions. By conducting the first heat treatment process in an inert atmosphere, a thin oxide film is formed on the side wall of the polycide tungsten/gate conductor layer. Then by conducting the second heat treatment process in an atmosphere with a strong oxidizing property, a thick oxide film without abnormal oxidation can be formed.
    Type: Application
    Filed: October 8, 2002
    Publication date: February 20, 2003
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Atul C. Ajmera, Karanam Balasubramanyam, Tomio Katata, Shang-Bin Ko
  • Publication number: 20030027392
    Abstract: A method for forming an ultra thin gate dielectric for an integrated circuit device is disclosed. In an exemplary embodiment of the invention, the method includes forming an initial nitride layer upon a substrate by rapidly heating the substrate in the presence of an ammonia (NH3) gas, and then re-oxidizing the initial nitride layer by rapidly heating the initial nitride layer in the presence of a nitric oxide (NO) gas, thereby forming an oxynitride layer. The oxynitride layer has a nitrogen concentration therein of at about 1.0×1015 atoms/cm2 to about 6.0×1015 atoms/cm2, and has a thickness which may be controlled within a sub 10 Å range.
    Type: Application
    Filed: August 1, 2001
    Publication date: February 6, 2003
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Evgeni Gousev, Atul C. Ajmera, Christopher P. D'Emic
  • Publication number: 20030010972
    Abstract: The present invention provides a method of preparing a Si-based metal-insulator-semiconductor (MIS) transistor which prevents the polycrystalline grains of the gate conductor from getting significantly larger by reducing the thermal budget of the sidewall oxidation process. The thermal budget of the inventive sidewall oxidation process is reduced one or two orders of magnitude over conventional prior art sidewall oxidation processes by utilizing atomic oxygen as the oxidizing ambient. The present invention also provides Si-based MIS transistors having a gate conductor having grain sizes of about 0.1, preferably 0.05, &mgr;m or less.
    Type: Application
    Filed: July 13, 2001
    Publication date: January 16, 2003
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Atul C. Ajmera, Omer H. Dokumaci, Bruce B. Doris, Oleg Gluschenkov
  • Patent number: 6506649
    Abstract: An innovative MOSFET having a raised source drain (RSD) is constructed prior to implanting source-drain dopants. The RSD structure thus built has a distinct advantage in that the offset from the RSD to the MOSFET channel is fully adjustable to minimize the overlap capacitance in the device. The RSD construction uses a selective epitaxial process to effectively reduce the drain-source resistance. This improvement is even more significant in thin-film SOI technology. Using an RSD, the film outside the channel area thickens which, in turn, reduces the parasitic resistance.
    Type: Grant
    Filed: March 19, 2001
    Date of Patent: January 14, 2003
    Assignee: International Business Machines Corporation
    Inventors: Ka Hing Fung, Atul C. Ajmera, Victor Ku, Dominic J. Schepis
  • Publication number: 20020192888
    Abstract: The present invention provides a method of formed a nitrided surface layer atop a polysilicon gate electrode that inhibits the growth of an epi silicon layer thereon. Specifically, the method of the present invention includes the steps of: forming a polysilicon layer atop a gate dielectric layer, forming a nitrided surface layer on the polysilicon layer; selectively removing portions of the nitrided surface layer and the polysilicon layer stopping on the gate dielectric layer, while leaving a patterned stack of the nitrided surface layer and the polysilicon layer on the gate dielectric layer; forming sidewall spacers on at least exposed vertical sidewalls of polysilicon layer; removing portions of the gate dielectric layer not protected by the sidewall spacers; and growing an epi silicon layer on exposed horizontal surfaces of an underlying semiconductor substrate.
    Type: Application
    Filed: June 27, 2002
    Publication date: December 19, 2002
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Atul C. Ajmera, Dominic J. Schepis, Michael D. Steigerwalt
  • Publication number: 20020142551
    Abstract: A CMOS structure and method of achieving self-aligned raised source/drain for CMOS structures on SOI without relying on selective epitaxial growth of silicon. In the method, CMOS structures are provided by performing sacraficial oxidation so that oxidation occurs on the surface of both the SOI and BOX interface. This allows for oxide spacer formation for gate-to-source/drain isolation which makes raised source/drain fabrication without increasing contact resistance possible.
    Type: Application
    Filed: March 29, 2001
    Publication date: October 3, 2002
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Heemyong Park, Fariborz Assaderaghi, Atul C. Ajmera, Ghavam G. Shahidi
  • Publication number: 20020132431
    Abstract: An innovative MOSFET having a raised source drain (RSD) is constructed prior to implanting source-drain dopants. The RSD structure thus built has a distinct advantage in that the offset from the RSD to the MOSFET channel is fully adjustable to minimize the overlap capacitance in the device. The RSD construction uses a selective epitaxial process to effectively reduce the drain-source resistance. This improvement is even more significant in thin-film SOI technology. Using an RSD, the film outside the channel area thickens which, in turn, reduces the parasitic resistance.
    Type: Application
    Filed: March 19, 2001
    Publication date: September 19, 2002
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Ka Hing Fung, Atul C. Ajmera, Victor Ku, Dominic J. Schepis
  • Patent number: 6440807
    Abstract: The present invention provides a method of formed a nitrided surface layer atop a polysilicon gate electrode that inhibits the growth of an epi silicon layer thereon. Specifically, the method of the present invention includes the steps of: forming a polysilicon layer atop a gate dielectric layer, forming a nitrided surface layer on the polysilicon layer; selectively removing portions of the nitrided surface layer and the polysilicon layer stopping on the gate dielectric layer, while leaving a patterned stack of the nitrided surface layer and the polysilicon layer on the gate dielectric layer; forming sidewall spacers on at least exposed vertical sidewalls of polysilicon layer; removing portions of the gate dielectric layer not protected by the sidewall spacers; and growing an epi silicon layer on exposed horizontal surfaces of an underlying semiconductor substrate.
    Type: Grant
    Filed: June 15, 2001
    Date of Patent: August 27, 2002
    Assignee: International Business Machines Corporation
    Inventors: Atul C. Ajmera, Dominic J. Schepis, Michael D. Steigerwalt
  • Patent number: 6437377
    Abstract: A notched gate MOS device includes either an encapsulated low dielectric material or encapsulated air or a vacuum at the bottom of a notched gate. Due to the low dielectric constant at the site of interface between the gate and the source/drain, the capacitance loss at that site is significantly reduced.
    Type: Grant
    Filed: January 24, 2001
    Date of Patent: August 20, 2002
    Assignee: International Business Machines Corporation
    Inventors: Atul C. Ajmera, Ka Hing (Samuel) Fung, Victor Ku, Dominic J. Schepis