Patents by Inventor John W. Palmour

John W. Palmour 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: 8119539
    Abstract: Methods of forming oxide layers on silicon carbide layers are disclosed, including placing a silicon carbide layer in a chamber such as an oxidation furnace tube that is substantially free of metallic impurities, heating an atmosphere of the chamber to a temperature of about 500° C. to about 1300° C., introducing atomic oxygen in the chamber, and flowing the atomic oxygen over a surface of the silicon carbide layer to thereby form an oxide layer on the silicon carbide layer. In some embodiments, introducing atomic includes oxygen providing a source oxide in the chamber and flowing a mixture of nitrogen and oxygen gas over the source oxide. The source oxide may comprise aluminum oxide or another oxide such as manganese oxide. Some methods include forming an oxide layer on a silicon carbide layer and annealing the oxide layer in an atmosphere including atomic oxygen.
    Type: Grant
    Filed: July 14, 2009
    Date of Patent: February 21, 2012
    Assignee: Cree, Inc.
    Inventors: Mrinal K. Das, Anant K. Agarwal, John W. Palmour, Dave Grider
  • Publication number: 20100009545
    Abstract: Methods of forming oxide layers on silicon carbide layers are disclosed, including placing a silicon carbide layer in a chamber such as an oxidation furnace tube that is substantially free of metallic impurities, heating an atmosphere of the chamber to a temperature of about 500° C. to about 1300° C., introducing atomic oxygen in the chamber, and flowing the atomic oxygen over a surface of the silicon carbide layer to thereby form an oxide layer on the silicon carbide layer. In some embodiments, introducing atomic includes oxygen providing a source oxide in the chamber and flowing a mixture of nitrogen and oxygen gas over the source oxide. The source oxide may comprise aluminum oxide or another oxide such as manganese oxide. Some methods include forming an oxide layer on a silicon carbide layer and annealing the oxide layer in an atmosphere including atomic oxygen.
    Type: Application
    Filed: July 14, 2009
    Publication date: January 14, 2010
    Inventors: Mrinal K. Das, Anant K. Agarwal, John W. Palmour, Dave Grider
  • Patent number: 7615801
    Abstract: High voltage silicon carbide (SiC) devices, for example, thyristors, are provided. A first SiC layer having a first conductivity type is provided on a first surface of a voltage blocking SiC substrate having a second conductivity type. A first region of SiC is provided on the first SiC layer and has the second conductivity type. A second region of SiC is provided in the first SiC layer, has the first conductivity type and is adjacent to the first region of SiC. A second SiC layer having the first conductivity type is provided on a second surface of the voltage blocking SiC substrate. A third region of SiC is provided on the second SiC layer and has the second conductivity type. A fourth region of SiC is provided in the second SiC layer, has the first conductivity type and is adjacent to the third region of SiC. First and second contacts are provided on the first and third regions of SiC, respectively. Related methods of fabricating high voltage SiC devices are also provided.
    Type: Grant
    Filed: June 23, 2005
    Date of Patent: November 10, 2009
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Jason R. Jenny, Mrinal K. Das, Anant K. Agarwal, John W. Palmour, Hudson McDonald Hobgood
  • Patent number: 7572741
    Abstract: Methods of forming oxide layers on silicon carbide layers are disclosed, including placing a silicon carbide layer in a chamber such as an oxidation furnace tube that is substantially free of metallic impurities, heating an atmosphere of the chamber to a temperature of about 500 ° C. to about 1300 ° C., introducing atomic oxygen in the chamber, and flowing the atomic oxygen over a surface of the silicon carbide layer to thereby form an oxide layer on the silicon carbide layer. In some embodiments, introducing atomic includes oxygen providing a source oxide in the chamber and flowing a mixture of nitrogen and oxygen gas over the source oxide. The source oxide may comprise aluminum oxide or another oxide such as manganese oxide. Some methods include forming an oxide layer on a silicon carbide layer and annealing the oxide layer in an atmosphere including atomic oxygen.
    Type: Grant
    Filed: September 16, 2005
    Date of Patent: August 11, 2009
    Assignee: Cree, Inc.
    Inventors: Mrinal K. Das, Anant K. Agarwal, John W. Palmour, Dave Grider
  • Publication number: 20090004883
    Abstract: Methods of forming oxide layers on silicon carbide layers are disclosed, including placing a silicon carbide layer in a chamber such as an oxidation furnace tube that is substantially free of metallic impurities, heating an atmosphere of the chamber to a temperature of about 500° C. to about 1300° C., introducing atomic oxygen in the chamber, and flowing the atomic oxygen over a surface of the silicon carbide layer to thereby form an oxide layer on the silicon carbide layer. In some embodiments, introducing atomic includes oxygen providing a source oxide in the chamber and flowing a mixture of nitrogen and oxygen gas over the source oxide. The source oxide may comprise aluminum oxide or another oxide such as manganese oxide. Some methods include forming an oxide layer on a silicon carbide layer and annealing the oxide layer in an atmosphere including atomic oxygen.
    Type: Application
    Filed: September 16, 2005
    Publication date: January 1, 2009
    Inventors: Mrinal K. Das, Anant K. Agarwal, John W. Palmour, Dave Grider
  • Patent number: 7414268
    Abstract: Silicon carbide high voltage semiconductor devices and methods of fabricating such devices are provided. The devices include a voltage blocking substrate. Insulated gate bipolar transistors are provided that have a voltage blocking substrate. Planar and beveled edge termination may be provided.
    Type: Grant
    Filed: May 18, 2005
    Date of Patent: August 19, 2008
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Jason R. Jenny, Mrinal K. Das, Hudson McDonald Hobgood, Anant K. Agarwal, John W. Palmour
  • Patent number: 7391057
    Abstract: High voltage silicon carbide (SiC) devices, for example, thyristors, are provided. A first SiC layer having a first conductivity type is provided on a first surface of a voltage blocking SiC substrate having a second conductivity type. A first region of SiC is provided on the first SiC layer and has the second conductivity type. A second region of SiC is provided in the first SiC layer. The second region of SiC has the first conductivity type and is adjacent to the first region of SiC. A second SiC layer having the first conductivity type is provided on a second surface, opposite the first surface, of the voltage blocking SiC substrate. First, second and third contacts are provided on the first region of SiC, the second region of SiC and the second SiC layer, respectively. Related methods of fabricating high voltage SiC devices are also provided.
    Type: Grant
    Filed: May 18, 2005
    Date of Patent: June 24, 2008
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Jason R. Jenny, Mrinal K. Das, Hudson McDonald Hobgood, Anant K. Agarwal, John W. Palmour
  • Patent number: 7135359
    Abstract: Large area silicon carbide devices, such as light-activated silicon carbide thyristors, having only two terminals are provided. The silicon carbide devices are selectively connected in parallel by a connecting plate. Silicon carbide thyristors are also provided having a portion of the gate region of the silicon carbide thyristors exposed so as to allow light of an energy greater than about 3.25 eV to activate the gate of the thyristor. The silicon carbide thyristors may be symmetric or asymmetrical. A plurality of the silicon carbide thyristors may be formed on a wafer, a portion of a wafer or multiple wafers. Bad cells may be determined and the good cells selectively connected by a connecting plate.
    Type: Grant
    Filed: May 14, 2004
    Date of Patent: November 14, 2006
    Assignee: Cree, Inc.
    Inventors: Anant Agarwal, Sei-Hyung Ryu, John W. Palmour
  • Patent number: 7067361
    Abstract: SiC MESFETs are disclosed which utilize a semi-insulating SiC substrate which substantially free of deep-level dopants. Utilization of the semi-insulating substrate may reduce back-gating effects in the MESFETs. Also provided are SiC MESFETs with a two recess gate structure. MESFETS with a selectively doped p-type buffer layer are also provided. Utilization of such a buffer layer may reduce output conductance by a factor of 3 and produce a 3 db increase in power gain over SiC MESFETs with conventional p-type buffer layers. A ground contact may also be provided to the p-type buffer layer and the p-type buffer layer may be made of two p-type layers with the layer formed on the substrate having a higher dopant concentration. SiC MESFETs according to embodiments of the present invention may also utilize chromium as a Schottky gate material. Furthermore, an oxide-nitride-oxide (ONO) passivation layer may be utilized to reduce surface effects in SiC MESFETs.
    Type: Grant
    Filed: November 12, 2003
    Date of Patent: June 27, 2006
    Assignee: Cree, Inc.
    Inventors: Scott T. Allen, John W. Palmour, Terrence S. Alcorn
  • Patent number: 6998322
    Abstract: Capacitors and interconnection structures for silicon carbide are provided having an oxide layer, a layer of dielectric material and a second oxide layer on the layer of dielectric material. The thickness of the oxide layers may be from about 0.5 to about 33 percent of the thickness of the oxide layers and the layer of dielectric material. Capacitors and interconnection structures for silicon carbide having silicon oxynitride layer as a dielectric structure are also provided. Such a dielectric structure may be between metal layers to provide a metal-insulator-metal capacitor or may be used as a inter-metal dielectric of an interconnect structure so as to provide devices and structures having improved mean time to failure. Methods of fabricating such capacitors and structures are also provided.
    Type: Grant
    Filed: March 6, 2003
    Date of Patent: February 14, 2006
    Assignee: Cree, Inc.
    Inventors: Mrinal Kanti Das, Lori A. Lipkin, John W. Palmour, Scott Sheppard, Helmut Hagleitner
  • Patent number: 6972436
    Abstract: Capacitors and interconnection structures for silicon carbide are provided having an oxide layer, a layer of dielectric material and a second oxide layer on the layer of dielectric material. The thickness of the oxide layers may be from about 0.5 to about 33 percent of the thickness of the oxide layers and the layer of dielectric material. Capacitors and interconnection structures for silicon carbide having silicon oxynitride layer as a dielectric structure are also provided. Such a dielectric structure may be between metal layers to provide a metal-insulator-metal capacitor or may be used as a inter-metal dielectric of an interconnect structure so as to provide devices and structures having improved mean time to failure. Methods of fabricating such capacitors and structures are also provided.
    Type: Grant
    Filed: June 11, 2001
    Date of Patent: December 6, 2005
    Assignee: Cree, Inc.
    Inventors: Mrinal Kanti Das, Lori A. Lipkin, John W. Palmour, Scott Sheppard, Helmut Hagleitner
  • Patent number: 6956238
    Abstract: Silicon carbide metal-oxide semiconductor field effect transistors (MOSFETs) and methods of fabricating silicon carbide MOSFETs are provided. The silicon carbide MOSFETs have an n-type silicon carbide drift layer, spaced apart p-type silicon carbide regions in the n-type silicon carbide drift layer and having n-type silicon carbide regions therein, and a nitrided oxide layer. The MOSFETs also have n-type shorting channels extending from respective ones of the n-type silicon carbide regions through the p-type silicon carbide regions to the n-type silicon carbide drift layer. In further embodiments, silicon carbide MOSFETs and methods of fabricating silicon carbide MOSFETs are provided that include a region that is configured to self-deplete the source region, between the n-type silicon carbide regions and the drift layer, adjacent the oxide layer, upon application of a zero gate bias.
    Type: Grant
    Filed: July 24, 2001
    Date of Patent: October 18, 2005
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Anant Agarwal, Mrinal Kanti Das, Lori A. Lipkin, John W. Palmour, Ranbir Singh
  • Publication number: 20040206976
    Abstract: Large area silicon carbide devices, such as light-activated silicon carbide thyristors, having only two terminals are provided. The silicon carbide devices are selectively connected in parallel by a connecting plate. Silicon carbide thyristors are also provided having a portion of the gate region of the silicon carbide thyristors exposed so as to allow light of an energy greater than about 3.25 eV to activate the gate of the thyristor. The silicon carbide thyristors may be symmetric or asymmetrical. A plurality of the silicon carbide thyristors may be formed on a wafer, a portion of a wafer or multiple wafers. Bad cells may be determined and the good cells selectively connected by a connecting plate.
    Type: Application
    Filed: May 14, 2004
    Publication date: October 21, 2004
    Inventors: Anant Agarwal, Sei-Hyung Ryu, John W. Palmour
  • Publication number: 20040159865
    Abstract: SiC MESFETs are disclosed which utilize a semi-insulating SiC substrate which substantially free of deep-level dopants. Utilization of the semi-insulating substrate may reduce back-gating effects in the MESFETs. Also provided are SiC MESFETs with a two recess gate structure. MESFETS with a selectively doped p-type buffer layer are also provided. Utilization of such a buffer layer may reduce output conductance by a factor of 3 and produce a 3 db increase in power gain over SiC MESFETs with conventional p-type buffer layers. A ground contact may also be provided to the p-type buffer layer and the p-type buffer layer may be made of two p-type layers with the layer formed on the substrate having a higher dopant concentration. SiC MESFETs according to embodiments of the present invention may also utilize chromium as a Schottky gate material. Furthermore, an oxide-nitride-oxide (ONO) passivation layer may be utilized to reduce surface effects in SiC MESFETs.
    Type: Application
    Filed: November 12, 2003
    Publication date: August 19, 2004
    Inventors: Scott T. Allen, John W. Palmour, Terrence S. Alcorn
  • Patent number: 6770911
    Abstract: Large area silicon carbide devices, such as light-activated silicon carbide thyristors, having only two terminals are provided. The silicon carbide devices are selectively connected in parallel by a connecting plate. Silicon carbide thyristors are also provided having a portion of the gate region of the silicon carbide thyristors exposed so as to allow light of an energy greater than about 3.25 eV to activate the gate of the thyristor. The silicon carbide thyristors may be symmetric or asymmetrical. A plurality of the silicon carbide thyristors may be formed on a wafer, a portion of a wafer or multiple wafers. Bad cells may be determined and the good cells selectively connected by a connecting plate.
    Type: Grant
    Filed: September 12, 2001
    Date of Patent: August 3, 2004
    Assignee: Cree, Inc.
    Inventors: Anant Agarwal, Sei-Hyung Ryu, John W. Palmour
  • Patent number: 6767843
    Abstract: Methods for fabricating a layer of oxide on a silicon carbide layer are provided by forming the oxide layer on the silicon carbide layer by oxidizing the silicon carbide layer in an N2O environment. A predetermined temperature profile and/or a predetermined flow rate profile of N2O are provided during the oxidation. The predetermined temperature profile and/or predetermined flow rate profile may be constant or variable and may include ramps to steady state conditions. The predetermined temperature profile and/or the predetermined flow rate profile are selected so as to reduce interface states of the oxide/silicon carbide interface with energies near the conduction band of SiC.
    Type: Grant
    Filed: October 1, 2001
    Date of Patent: July 27, 2004
    Assignee: Cree, Inc.
    Inventors: Lori A. Lipkin, Mrinal Kanti Das, John W. Palmour
  • Patent number: 6686616
    Abstract: SiC MESFETs are disclosed which utilize a semi-insulating SiC substrate which substantially free of deep-level dopants. Utilization of the semi-insulating substrate may reduce back-gating effects in the MESFETs. Also provided are SiC MESFETs with a two recess gate structure. MESFETS with a selectively doped p-type buffer layer are also provided. Utilization of such a buffer layer may reduce output conductance by a factor of 3 and produce a 3 db increase in power gain over SiC MESFETs with conventional p-type buffer layers. A ground contact may also be provided to the p-type buffer layer and the p-type buffer layer may be made of two p-type layers with the layer formed on the substrate having a higher dopant concentration. SiC MESFETs according to embodiments of the present invention may also utilize chromium as a Schottky gate material. Furthermore, an oxide-nitride-oxide (ONO) passivation layer may be utilized to reduce surface effects in SiC MESFETs.
    Type: Grant
    Filed: May 10, 2000
    Date of Patent: February 3, 2004
    Assignee: Cree, Inc.
    Inventors: Scott T. Allen, John W. Palmour, Terrence S. Alcorn
  • Publication number: 20030160274
    Abstract: Capacitors and interconnection structures for silicon carbide are provided having an oxide layer, a layer of dielectric material and a second oxide layer on the layer of dielectric material. The thickness of the oxide layers may be from about 0.5 to about 33 percent of the thickness of the oxide layers and the layer of dielectric material. Capacitors and interconnection structures for silicon carbide having silicon oxynitride layer as a dielectric structure are also provided. Such a dielectric structure may be between metal layers to provide a metal-insulator-metal capacitor or may be used as a inter-metal dielectric of an interconnect structure so as to provide devices and structures having improved mean time to failure. Methods of fabricating such capacitors and structures are also provided.
    Type: Application
    Filed: March 6, 2003
    Publication date: August 28, 2003
    Inventors: Mrinal Kanti Das, Lori A. Lipkin, John W. Palmour, Scott Sheppard, Helmut Hagleitner
  • Publication number: 20030047748
    Abstract: Large area silicon carbide devices, such as light-activated silicon carbide thyristors, having only two terminals are provided. The silicon carbide devices are selectively connected in parallel by a connecting plate. Silicon carbide thyristors are also provided having a portion of the gate region of the silicon carbide thyristors exposed so as to allow light of an energy greater than about 3.25 eV to activate the gate of the thyristor. The silicon carbide thyristors may be symmetric or asymmetrical. A plurality of the silicon carbide thyristors may be formed on a wafer, a portion of a wafer or multiple wafers. Bad cells may be determined and the good cells selectively connected by a connecting plate.
    Type: Application
    Filed: September 12, 2001
    Publication date: March 13, 2003
    Inventors: Anant Agarwal, Sei-Hyung Ryu, John W. Palmour
  • Patent number: 6514779
    Abstract: A silicon carbide device is fabricated by forming a plurality of a same type of silicon carbide devices on at least a portion of a silicon carbide wafer in a predefined pattern. The silicon carbide devices have corresponding first contacts on a first face of the silicon carbide wafer. The plurality of silicon carbide devices are electrically, tested to identify ones of the plurality of silicon carbide devices which pass an electrical test. The first contact of the identified ones of the silicon carbide devices are then selectively interconnected. Devices having a plurality of selectively connected silicon carbide devices of the same type are also provided.
    Type: Grant
    Filed: October 17, 2001
    Date of Patent: February 4, 2003
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Anant Agarwal, Craig Capell, John W. Palmour