Patents by Inventor David Ahlgren

David Ahlgren 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: 20070218641
    Abstract: A system and method comprises forming an intrinsic base on a collector. The system and method further includes forming a fully silicided extrinsic base on the intrinsic base by a self-limiting silicidation process at a predetermined temperature and for a predetermined amount of time, the silicidation substantially stopping at the intrinsic base. The system and method further includes forming an emitter which is physically insulated from the extrinsic base and the collector, and which is in physical contact with the intrinsic base.
    Type: Application
    Filed: March 14, 2006
    Publication date: September 20, 2007
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: David Ahlgren, Guy Cohen, Christian Lavoie, Francois Pagette, Anna Topol
  • Publication number: 20070145533
    Abstract: A bipolar transistor has a collector that is contacted directly beneath a base-collector junction by metallization to reduce collector resistance. A conventional reach-through and buried layer, as well as their associated resistance, are eliminated. The transistor is well isolated, nearly eliminating well-to-substrate capacitance and device-to-device leakage current. The structure provides for improved electrical performance, including improved fT, Fmax and drive current.
    Type: Application
    Filed: February 22, 2007
    Publication date: June 28, 2007
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: David AHLGREN, Gregory FREEMAN, Francois PAGETTE, Christopher SCHNABEL, Anna TOPOL
  • Publication number: 20050269664
    Abstract: A bipolar transistor has a collector that is contacted directly beneath a base-collector junction by metallization to reduce collector resistance. A conventional reach-through and buried layer, as well as their associated resistance, are eliminated. The transistor is well isolated, nearly eliminating well-to-substrate capacitance and device-to-device leakage current. The structure provides for improved electrical performance, including improved fT, Fmax and drive current.
    Type: Application
    Filed: June 4, 2004
    Publication date: December 8, 2005
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: David Ahlgren, Gregory Freeman, Francois Pagette, Christopher Schnabel, Anna Topol
  • Publication number: 20050242373
    Abstract: The present invention provides a bipolar transistor having a raised extrinsic base silicide and an emitter contact border that are self-aligned. The bipolar transistor of the present invention exhibit reduced parasitics as compared with bipolar transistors that do not include a self-aligned silicide and a self-aligned emitter contact border. The present invention also is related to methods of fabricating the inventive bipolar transistor structure. In the methods of the present invention, a block emitter polysilicon region replaces a conventional T-shaped emitter polysilicon.
    Type: Application
    Filed: July 5, 2005
    Publication date: November 3, 2005
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: David Ahlgren, Gregory Freeman, Marwan Khater, Richard Volant
  • Publication number: 20050212027
    Abstract: A method of forming a trench in a semiconductor substrate includes a step of converting the cross section of the upper portion of the trench from octagonal to rectangular, so that sensitivity to alignment errors between the trench lithography and the active area lithography is reduced. Applications include a vertical transistor that becomes insensitive to misalignment between the trench and the litho for the active area, in particular a DRAM cell with a vertical transistor.
    Type: Application
    Filed: March 29, 2004
    Publication date: September 29, 2005
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Thomas Adam, David Ahlgren, Kangguo Cheng, Ramachandra Divakaruni
  • Publication number: 20050121748
    Abstract: The present invention provides a bipolar transistor having a raised extrinsic base silicide and an emitter contact border that are self-aligned. The bipolar transistor of the present invention exhibit reduced parasitics as compared with bipolar transistors that do not include a self-aligned silicide and a self-aligned emitter contact border. The present invention also is related to methods of fabricating the inventive bipolar transistor structure. In the methods of the present invention, a block emitter polysilicon region replaces a conventional T-shaped emitter polysilicon.
    Type: Application
    Filed: December 4, 2003
    Publication date: June 9, 2005
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: David Ahlgren, Gregory Freeman, Marwan Khater, Richard Volant
  • Patent number: 5656514
    Abstract: A high gain, high frequency transistor is formed having a combination of a moderately doped retrograde emitter and a collector which is formed by self-aligned implantation through an emitter opening window. This combination allows continued base width scaling and ensures high current capability yet limits the electric field at the emitter-base junction, particularly near the base contacts, in order to reduce leakage and capacitance and to enhance breakdown voltage. Cut-off frequencies on the order of 100 GHz can thus be obtained in the performance of a transistor with a 30 nm base width in a SiGe device.
    Type: Grant
    Filed: November 22, 1994
    Date of Patent: August 12, 1997
    Assignee: International Business Machines Corporation
    Inventors: David Ahlgren, Jack Chu, Martin Revitz, Paul Ronsheim, Mary Saccamango, David Sunderland