Patents by Inventor Richard W. Foote

Richard W. Foote 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: 8946780
    Abstract: A semiconductor device includes a first layer and a second layer over the first layer. The first and second layers are configured to form an electron gas layer at an interface of the first and second layers. The semiconductor device also includes an Ohmic contact and multiple conductive vias through the second layer. The conductive vias are configured to electrically couple the Ohmic contact to the electron gas layer. The conductive vias could have substantially vertical sidewalls or substantially sloped sidewalls, or the conductive vias could form a nano-textured surface on the Ohmic contact. The first layer could include Group III-nitride nucleation, buffer, and channel layers, and the second layer could include a Group III-nitride barrier layer.
    Type: Grant
    Filed: March 1, 2011
    Date of Patent: February 3, 2015
    Assignee: National Semiconductor Corporation
    Inventors: Sandeep R. Bahl, Richard W. Foote, Jr.
  • Patent number: 8298901
    Abstract: An improved method for manufacturing bipolar transistors is disclosed. The method for forming a PNP transistor comprises the steps of forming a P type collector on a substrate, forming a PNP epitaxial base on the P type collector, forming a PNP extrinsic base in the PNP epitaxial base, and forming a PNP emitter in contact with the PNP extrinsic base. The method for forming an NPN transistor comprises the steps of forming an N type collector on a substrate, forming a NPN epitaxial base on the N type collector, forming an NPN extrinsic base in the NPN epitaxial base, and forming an NPN emitter in contact with the NPN extrinsic base. The PNP and NPN transistors may be manufactured in the same control flow process.
    Type: Grant
    Filed: May 26, 2006
    Date of Patent: October 30, 2012
    Assignee: National Semiconductor Corporation
    Inventors: Richard W. Foote, Edward F. Pressley, Joseph A. DeSantis, Alexei Sadovnikov, Christoher J. Knorr
  • Publication number: 20120223317
    Abstract: A semiconductor device includes a first layer and a second layer over the first layer. The first and second layers are configured to form an electron gas layer at an interface of the first and second layers. The semiconductor device also includes an Ohmic contact and multiple conductive vias through the second layer. The conductive vias are configured to electrically couple the Ohmic contact to the electron gas layer. The conductive vias could have substantially vertical sidewalls or substantially sloped sidewalls, or the conductive vias could form a nano-textured surface on the Ohmic contact. The first layer could include Group III-nitride nucleation, buffer, and channel layers, and the second layer could include a Group III-nitride barrier layer.
    Type: Application
    Filed: March 1, 2011
    Publication date: September 6, 2012
    Applicant: NATIONAL SEMICONDUCTOR CORPORATION
    Inventors: Sandeep R. Bahl, Richard W. Foote, JR.
  • Patent number: 7939402
    Abstract: A method for manufacturing a semiconductor apparatus is disclosed. The apparatus comprises double poly bipolar transistors and double poly metal oxide semiconductor (MOS) transistors. The bipolar transistors and the MOS transistors are manufactured in a unified process in which a first polysilicon layer (Poly1) is doped to form the extrinsic bases in the bipolar transistors and to form the gates in the MOS transistors. A second polysilicon layer (Poly2) is doped to form emitters in the bipolar transistors and to form the sources and drains in the MOS transistors. The method of the invention minimizes the number of manufacturing process steps.
    Type: Grant
    Filed: December 17, 2009
    Date of Patent: May 10, 2011
    Assignee: National Semiconductor Corporation
    Inventors: Richard W. Foote, Robert Oliver
  • Publication number: 20110065256
    Abstract: An efficient method is disclosed for increasing the breakdown voltage of an integrated circuit device that is isolated by a local oxidation of silicon (LOCOS) process. The method comprises forming a portion of a field oxide in an integrated circuit so that the field oxide has a gradual profile. The gradual profile of the field oxide reduces impact ionization in the field oxide by creating a reduced value of electric field for a given value of applied voltage. The reduction in impact ionization increases the breakdown voltage of the integrated circuit. The gradual profile is formed by using an increased thickness of pad oxide and a reduced thickness of silicon nitride during a field oxide oxidation process.
    Type: Application
    Filed: November 29, 2010
    Publication date: March 17, 2011
    Applicant: National Semiconductor Corporation
    Inventors: Richard W. Foote, JR., Terry Lee Lines, Alexei Sadovnikov, Andy Strachan
  • Patent number: 7879694
    Abstract: A system and method is described for applying a pre-gate plasma etch in a semiconductor device manufacturing process in order to increase the integrity of a subsequently grown gate oxide layer. During the manufacture of a semiconductor device a sacrificial oxide layer is grown over a silicon substrate. The pre-gate plasma etch process is applied to the sacrificial oxide layer. Then the sacrificial oxide layer is stripped away and a gate oxide layer is grown over the silicon substrate. The gate oxide layer has an increased integrity due to the application of the pre-gate plasma etch process.
    Type: Grant
    Filed: April 14, 2008
    Date of Patent: February 1, 2011
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote
  • Patent number: 7867871
    Abstract: An efficient method is disclosed for increasing the breakdown voltage of an integrated circuit device that is isolated by a local oxidation of silicon (LOCOS) process. The method comprises forming a portion of a field oxide in an integrated circuit so that the field oxide has a gradual profile. The gradual profile of the field oxide reduces impact ionization in the field oxide by creating a reduced value of electric field for a given value of applied voltage. The reduction in impact ionization increases the breakdown voltage of the integrated circuit. The gradual profile is formed by using an increased thickness of pad oxide and a reduced thickness of silicon nitride during a field oxide oxidation process.
    Type: Grant
    Filed: July 13, 2006
    Date of Patent: January 11, 2011
    Assignee: National Semiconductor Corporation
    Inventors: Richard W. Foote, Terry Lee Lines, Alexei Sadovnikov, Andy Strachan
  • Patent number: 7863153
    Abstract: An efficient method is disclosed for creating different field oxide profiles in a local oxidation of silicon process (LOCOS process). The method comprises (1) forming a first portion of the field oxide with a first field oxide profile (e.g., an abrupt bird's beak profile) during a field oxide oxidation process, and (2) forming a second portion of the field oxide with a second field oxide profile (e.g., a graded bird's beak profile) during the field oxide oxidation process. A graded bird's beak profile enables higher breakdown voltages. An abrupt bird's beak profile enables higher packing densities. The method gives an integrated circuit designer the flexibility to create an appropriate field oxide profile at a desired location.
    Type: Grant
    Filed: July 13, 2006
    Date of Patent: January 4, 2011
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote, Jr.
  • Patent number: 7808048
    Abstract: A buried thin film resistor having end caps defined by a dielectric mask is disclosed. A thin film resistor is formed on an integrated circuit substrate. A resistor protect layer is formed over the thin film resistor. A layer of dielectric material is formed over the resistor protect layer. The dielectric material is masked and dry etched to leave a first portion of dielectric material over a first end of the thin film resistor and a second portion of dielectric material over a second end of the thin film resistor. The resistor protect layer is then wet etched using the first and second portions of the dielectric material as a hard mask. Then a second dielectric layer is deposited and vias are etched down to the underlying portions of the resistor protect layer.
    Type: Grant
    Filed: October 15, 2007
    Date of Patent: October 5, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Rodney Hill, Victor Torres, William Max Coppock, Richard W. Foote, Jr., Terry L. Lines, Tom Bold
  • Patent number: 7772653
    Abstract: A method for manufacturing a semiconductor apparatus is disclosed. The apparatus comprises double poly bipolar transistors and double poly metal oxide semiconductor (MOS) transistors. The bipolar transistors and the MOS transistors are manufactured in a unified process in which a first polysilicon layer (Poly1) is doped to form the extrinsic bases in the bipolar transistors and to form the gates in the MOS transistors. A second polysilicon layer (Poly2) is doped to form emitters in the bipolar transistors and to form the sources and drains in the MOS transistors. The method of the invention minimizes the number of manufacturing process steps.
    Type: Grant
    Filed: February 11, 2004
    Date of Patent: August 10, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Richard W. Foote, Robert Oliver
  • Patent number: 7745902
    Abstract: A system and method is disclosed for providing improved trench isolation of semiconductor devices. An isolation trench of the present invention is manufactured as follows. A substrate of a semiconductor device is provided and a trench is etched in the substrate. Then a silicon liner is grown in the trench. The trench is then filled with polysilicon material. Polysilicon material is also deposited on top of the filled trench to protect the silicon dioxide liner from the effects of subsequent etch procedures and oxidation procedures. The initial height of the polysilicon material is selected to be large enough to allow the polysilicon material to survive the subsequent etch procedures and oxidation procedures.
    Type: Grant
    Filed: September 21, 2007
    Date of Patent: June 29, 2010
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote
  • Patent number: 7589397
    Abstract: A system and method is disclosed for using a differential wet etch stop technique to provide a uniform oxide layer over a metal layer in a laser trimmed fuse. A layer of boron doped oxide with a slow etch rate is placed over the metal layer. A layer of phosphorus doped oxide with a fast etch rate is placed over the boron doped oxide. The time period required for a wet etch process to etch through the phosphorus doped oxide is calculated. The wet etch process is then applied to the phosphorus doped oxide for the calculated time period. The wet etch process slows significantly when it reaches the boron doped oxide. This method forms a uniform layer of boron doped oxide over the metal layer.
    Type: Grant
    Filed: June 11, 2007
    Date of Patent: September 15, 2009
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote
  • Patent number: 7547618
    Abstract: A system and method is disclosed for providing a deep connection to a substrate or buried layer of a semiconductor device. Three shallow trenches are etched halfway through a layer of epitaxial silicon that is located on a substrate. A second doped layer is created in the epitaxial silicon layer at the bottom of the central shallow trench. First and third doped layers are created in the epitaxial silicon layer adjacent to the central shallow trench. An oxide layer is then deposited to fill the three trenches. The second doped layer is diffused vertically down to the substrate. The first and third doped layers are diffused vertically down to the second doped layer. Lateral diffusion of the first and third doped layers is constrained by the oxide layer in the three trenches.
    Type: Grant
    Filed: July 26, 2007
    Date of Patent: June 16, 2009
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote
  • Patent number: 7522973
    Abstract: A method for preparing both main label and warning label portions for a container useful in dispensing drugs by a pharmacist in which the main label portion contains specific drug or patient information and the warning label portion contains one or more warnings specific to the drug or patient information.
    Type: Grant
    Filed: May 25, 2007
    Date of Patent: April 21, 2009
    Assignee: ABP Patent Holdings, LLC
    Inventors: Richard W. Foote, Carlos R. Young
  • Patent number: 7470594
    Abstract: A method is disclosed for controlling the formation of an interfacial oxide layer in a polysilicon emitter transistor device. The interfacial oxide layer is formed between an underlying substrate of single crystal silicon and an upper layer of polysilicon. The current gain and the emitter resistance of the transistor device are related to the thickness of the interfacial oxide layer. The oxide of the interfacial oxide layer is grown in a low pressure, low temperature pure oxygen (O2) environment that greatly reduces the oxidation rate. The low oxidation rate allows the thickness of the interfacial oxide layer to be precisely controlled and sources of variation to be minimized in the manufacturing process.
    Type: Grant
    Filed: December 14, 2005
    Date of Patent: December 30, 2008
    Assignee: National Semiconductor Corporation
    Inventors: Richard W. Foote, Jr., William Max Coppock, Darren Lee Rust, Charles A. Dark
  • Patent number: 7456097
    Abstract: A system and method is disclosed for providing an etch procedure to facet the top corners of a via in a semiconductor device. A vertical anisotropic dry etch process is applied through an aperture in a resist mask to etch through a dielectric layer down to a bottom conductor layer. The resist mask is removed and an etch process is applied to etch away corner portions of the dielectric layer. The etch process forms a flat sidewall surface in the portions of the dielectric layer that form the via. The flat sidewall surface is disposed at an obtuse angle with respect to the top surface of the dielectric layer and at an obtuse angle with respect to a vertical sidewall of the via cavity. The flat sidewall surface and the absence of sharp corners facilitate a subsequent metal fill process.
    Type: Grant
    Filed: November 30, 2004
    Date of Patent: November 25, 2008
    Assignee: National Semiconductor Corporation
    Inventors: Rodney Hill, Victor M. Torres, Richard W. Foote, Jr.
  • Patent number: 7348639
    Abstract: A system and method is disclosed for providing a deep connection to a substrate or buried layer of a semiconductor device. Three shallow trenches are etched halfway through a layer of epitaxial silicon that is located on a substrate. A second doped layer is created in the epitaxial silicon layer at the bottom of the central shallow trench. First and third doped layers are created in the epitaxial silicon layer adjacent to the central shallow trench. An oxide layer is then deposited to fill the three trenches. The second doped layer is diffused vertically down to the substrate. The first and third doped layers are diffused vertically down to the second doped layer. Lateral diffusion of the first and third doped layers is constrained by the oxide layer in the three trenches.
    Type: Grant
    Filed: May 7, 2007
    Date of Patent: March 25, 2008
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote
  • Patent number: 7332794
    Abstract: A system and method is disclosed for providing a self heating adjustable titanium disilicon (TiSi2) resistor. A triangularly shaped layer of polysilicon is placed a layer of insulation material. A layer of titanium is applied over the polysilicon and heated to form a layer of C49 type of TiSi2. A current is then applied to the small end of the triangularly shaped layer of C49 TiSi2. The current generates heat in a high resistance portion of the triangularly shaped layer of C49 TiSi2 and converts a portion of the C49 TiSi2 to C54 TiSi2. The lower resistance of the C54 TiSi2 decreases the effective resistance of the resistor. A desired value of resistance may be selected by adjusting the magnitude of the applied current.
    Type: Grant
    Filed: December 14, 2006
    Date of Patent: February 19, 2008
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote
  • Patent number: 7332403
    Abstract: A buried thin film resistor having end caps defined by a dielectric mask is disclosed. A thin film resistor is formed on an integrated circuit substrate. A resistor protect layer is formed over the thin film resistor. A layer of dielectric material is formed over the resistor protect layer. The dielectric material is masked and dry etched to leave a first portion of dielectric material over a first end of the thin film resistor and a second portion of dielectric material over a second end of the thin film resistor. The resistor protect layer is then wet etched using the first and second portions of the dielectric material as a hard mask. Then a second dielectric layer is deposited and vias are etched down to the underlying portions of the resistor protect layer.
    Type: Grant
    Filed: July 11, 2005
    Date of Patent: February 19, 2008
    Assignee: National Semiconductor Corporation
    Inventors: Rodney Hill, Victor Torres, William Max Coppock, Richard W. Foote, Jr., Terry L. Lines, Tom Bold
  • Patent number: 7291541
    Abstract: A system and method is disclosed for providing improved trench isolation of semiconductor devices. An isolation trench of the present invention is manufactured as follows. A substrate of a semiconductor device is provided and a trench is etched in the substrate. Then a silicon liner is grown in the trench. The trench is then filled with polysilicon material. Polysilicon material is also deposited on top of the filled trench to protect the silicon dioxide liner from the effects of subsequent etch procedures and oxidation procedures. The initial height of the polysilicon material is selected to be large enough to allow the polysilicon material to survive the subsequent etch procedures and oxidation procedures.
    Type: Grant
    Filed: March 18, 2004
    Date of Patent: November 6, 2007
    Assignee: National Semiconductor Corporation
    Inventor: Richard W. Foote