Patents by Inventor Anant Agarwal

Anant Agarwal 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: 20090146154
    Abstract: A transistor structure optimizes current along the A-face of a silicon carbide body to form an AMOSFET that minimizes the JFET effect in the drift region during forward conduction in the on-state. The AMOSFET further shows high voltage blocking ability due to the addition of a highly doped well region that protects the gate corner region in a trench-gated device. The AMOSFET uses the A-face conduction along a trench sidewall in addition to a buried channel layer extending across portions of the semiconductor mesas defining the trench. A doped well extends from at least one of the mesas to a depth within the current spreading layer that is greater than the depth of the trench. A current spreading layer extends between the semiconductor mesas beneath the bottom of the trench to reduce junction resistance in the on-state. A buffer layer between the trench and the deep well further provides protection from field crowding at the trench corner.
    Type: Application
    Filed: December 7, 2007
    Publication date: June 11, 2009
    Applicant: Cree, Inc.
    Inventors: Qingchun Zhang, Anant Agarwal, Charlotte Jonas
  • Patent number: 7543279
    Abstract: A program execution data trace is created by instrumenting a program to record value sets during execution and an instruction trace. By simulating instructions either backward or forward from a first instruction associated with a recorded value set to a second instruction according to the instruction trace, a value set is determined for the second instruction. Backward and forward simulation can be combined to complement each other. For backward simulation, a table of simulation instructions is preferably maintained, which associates program instructions encountered in the instruction trace with simulation instructions which reverse the operation of the associated program instructions. Preferably, one or more probes is inserted into the program to save values of particular variables whose value may be difficult to determine. Preferably, the instruction trace is displayed alongside and correlated with the data trace.
    Type: Grant
    Filed: May 25, 2004
    Date of Patent: June 2, 2009
    Assignee: Symantec Operating Corporation
    Inventors: Andrew E. Ayers, Richard Schooler, Anant Agarwal
  • Patent number: 7539845
    Abstract: An integrated circuit comprises a plurality of tiles. Each tile comprises a processor, and a switch including switching circuitry to forward data received over data paths from other tiles to the processor and to switches of other tiles, and to forward data received from the processor to switches of other tiles. The integrated circuit further comprises an interface coupled to a plurality of the tiles to transfer data between one or more switches of the tiles and one or more switches of tiles in an externally coupled integrated circuit.
    Type: Grant
    Filed: April 14, 2006
    Date of Patent: May 26, 2009
    Assignee: Tilera Corporation
    Inventors: David Wentzlaff, Carl G. Ramey, Anant Agarwal
  • Patent number: 7461210
    Abstract: Managing memory includes: mediating access to a first memory as a cache for a second memory; and associating one of a plurality of entry types with entries in the cache. Data from the second memory associated with a first type is not allowed to evict a cache entry associated with a second type.
    Type: Grant
    Filed: April 14, 2006
    Date of Patent: December 2, 2008
    Assignee: Tilera Corporation
    Inventors: David Wentzlaff, Matthew Mattina, Anant Agarwal
  • Publication number: 20080256328
    Abstract: Methods and apparatus related to memory indexing. Receiving indications of an indexing function for use with a memory. Performing indexing functions with a processor before addressing a memory location. Referencing a customizable lookup table to determine a memory location. Translating a computer program to control a computer system to use a desired indexing function. Determining desired indexing functions based on performance of a computer system.
    Type: Application
    Filed: April 12, 2007
    Publication date: October 16, 2008
    Applicant: Massachusetts Institute of Technology
    Inventors: Shripad Nagarkar, Anant Agarwal, Rodric Rabbah
  • Patent number: 7394288
    Abstract: An integrated circuit includes a plurality of tiles. Each tile includes a processor, a switch including switching circuitry to forward data over data paths from other tiles to the processor and to switches of other tiles, and a switch memory that stores instruction streams that are able to operate independently for respective output ports of the switch.
    Type: Grant
    Filed: December 13, 2005
    Date of Patent: July 1, 2008
    Assignee: Massachusetts Institute of Technology
    Inventor: Anant Agarwal
  • Publication number: 20080121993
    Abstract: A semiconductor device includes a drift layer having a first conductivity type and a body region adjacent the drift layer. The body region has a second conductivity type opposite the first conductivity type and forms a p-n junction with the drift layer. The device further includes a contactor region in the body region and having the first conductivity type, and a shunt channel region extending through the body region from the contactor region to the drift layer. The shunt channel region has the first conductivity type. The device further includes a first terminal in electrical contact with the body region and the contactor region, and a second terminal in electrical contact with the drift layer.
    Type: Application
    Filed: November 3, 2006
    Publication date: May 29, 2008
    Inventors: Allen Hefner, Sei-Hyung Ryu, Anant Agarwal
  • Publication number: 20080029838
    Abstract: A semiconductor device includes a semiconductor layer having a first conductivity type, a metal contact on the semiconductor layer and forming a Schottky junction with the semiconductor layer, and a semiconductor region in the semiconductor layer. The semiconductor region and the semiconductor layer form a first p-n junction in parallel with the Schottky junction. The first p-n junction is configured to generate a depletion region in the semiconductor layer adjacent the Schottky junction when the Schottky junction is reversed biased to thereby limit reverse leakage current through the Schottky junction. The first p-n junction is further configured such that punch-through of the first p-n junction occurs at a lower voltage than a breakdown voltage of the Schottky junction when the Schottky junction is reverse biased.
    Type: Application
    Filed: August 1, 2006
    Publication date: February 7, 2008
    Inventors: Qingchun Zhang, Sei-Hyung Ryu, Anant Agarwal
  • Publication number: 20070235757
    Abstract: Bipolar junction transistors (BJTs) are provided including silicon carbide (SiC) substrates. An epitaxial SiC base region is provided on the SiC substrate. The epitaxial SiC base region has a first conductivity type. An epitaxial SiC emitter region is also provided on the SiC substrate. The epitaxial SiC emitter region has a second conductivity type, different from the first conductivity type. The epitaxial SiC emitter region has first and second portions. The first portion is provided on the SiC substrate and the second portion is provided on the first portion. The second portion has a higher carrier concentration than the first portion. Related methods of fabricating BJTs are also provided herein.
    Type: Application
    Filed: September 16, 2005
    Publication date: October 11, 2007
    Inventors: Anant Agarwal, Sumithra Krishnaswami, Sei-Hyung Ryu, Edward Hurt
  • Publication number: 20070145378
    Abstract: A bipolar junction transistor (BJT) includes a silicon carbide (SiC) collector layer of first conductivity type, an epitaxial silicon carbide base layer of second conductivity type on the silicon carbide collector layer, and an epitaxial silicon carbide emitter mesa of the first conductivity type on the epitaxial silicon carbide base layer. An epitaxial silicon carbide passivation layer of the first conductivity type is provided on at least a portion of the epitaxial silicon carbide base layer outside the silicon carbide emitter mesa. The epitaxial silicon carbide passivation layer can be configured to fully deplete at zero device bias. Related fabrication methods also are disclosed.
    Type: Application
    Filed: December 22, 2005
    Publication date: June 28, 2007
    Inventors: Anant Agarwal, Sumithra Krishnaswami, Sei-Hyung Ryu, D. Capell
  • Publication number: 20070066039
    Abstract: Methods of forming a silicon carbide semiconductor device are disclosed. The methods include forming a semiconductor device at a first surface of a silicon carbide substrate having a first thickness, and mounting a carrier substrate to the first surface of the silicon carbide substrate. The carrier substrate provides mechanical support to the silicon carbide substrate. The methods further include thinning the silicon carbide substrate to a thickness less the first thickness, forming a metal layer on the thinned silicon carbide substrate opposite the first surface of the silicon carbide substrate, and locally annealing the metal layer to form an ohmic contact on the thinned silicon carbide substrate opposite the first surface of the silicon carbide substrate. The silicon carbide substrate is singulated to provide a singulated semiconductor device.
    Type: Application
    Filed: September 14, 2006
    Publication date: March 22, 2007
    Inventors: Anant Agarwal, Sei-Hyung Ryu, Matthew Donofrio
  • Publication number: 20060261345
    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: Application
    Filed: May 18, 2005
    Publication date: November 23, 2006
    Inventors: Sei-Hyung Ryu, Jason Jenny, Mrinal Das, Hudson Hobgood, Anant Agarwal, John Palmour
  • Publication number: 20060261346
    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: Application
    Filed: May 18, 2005
    Publication date: November 23, 2006
    Inventors: Sei-Hyung Ryu, Jason Jenny, Mrinal Das, Anant Agarwal, John Palmour, Hudson Hobgood
  • Publication number: 20060261348
    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: Application
    Filed: June 23, 2005
    Publication date: November 23, 2006
    Inventors: Sei-Hyung Ryu, Jason Jenny, Mrinal Das, Anant Agarwal, John Palmour, Hudson Hobgood
  • Publication number: 20060261876
    Abstract: An electronic circuit includes a primary wide bandgap bipolar power switching device configured to supply a load current in response to a control signal applied to a control terminal thereof, and a driver device configured to generate the control signal. At least one of the primary switching device or the driver device may include an optically triggered switching device. A discrete wide bandgap semiconductor device includes a primary bipolar device stage configured to switch between a conducting state and a nonconducting state upon application of a control current, and a bipolar driver stage configured to generate the control current and to supply the control current to the primary bipolar device stage. At least one of the primary bipolar device stage and the bipolar driver stage may include an optically triggered wide bandgap switching device.
    Type: Application
    Filed: April 27, 2006
    Publication date: November 23, 2006
    Inventors: Anant Agarwal, Sumithra Krishnaswami, James Richmond
  • Publication number: 20060261347
    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: Application
    Filed: May 18, 2005
    Publication date: November 23, 2006
    Inventors: Sei-Hyung Ryu, Jason Jenny, Mrinal Das, Hudson Hobgood, Anant Agarwal, John Palmour
  • Publication number: 20060255423
    Abstract: Integral structures that block the current conduction of the built-in PiN diode in a junction barrier Schottky (JBS) structure are provided. A Schottky diode may be incorporated in series with the PiN diode, where the Schottky diode is of opposite direction to that of the PiN diode. A series resistance or and insulating layer may be provided between the PiN diode and a Schottky contact. Silicon carbide Schottky diodes and methods of fabricating silicon carbide Schottky diodes that include a silicon carbide junction barrier region disposed within a drift region of the diode are also provided. The junction barrier region includes a first region of silicon carbide having a first doping concentration in the drift region of the diode and a second region of silicon carbide in the drift region and disposed between the first region of silicon carbide and a Schottky contact of the Schottky diode. The second region is in contact with the first region of silicon carbide and the Schottky contact.
    Type: Application
    Filed: May 11, 2005
    Publication date: November 16, 2006
    Inventors: Sei-Hyung Ryu, Anant Agarwal
  • 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
  • Publication number: 20060118792
    Abstract: An edge termination structure for a silicon carbide semiconductor device includes a plurality of spaced apart concentric floating guard rings in a silicon carbide layer that at least partially surround a silicon carbide-based junction, an insulating layer on the floating guard rings, and a silicon carbide surface charge compensation region between the floating guard rings and adjacent the surface of the silicon carbide layer. A silicon nitride layer is on the silicon carbide layer, and an organic protective layer is on the silicon nitride layer. An oxide layer may be between the silicon nitride layer and the surface of the silicon carbide layer. Methods of forming edge termination structures are also disclosed.
    Type: Application
    Filed: January 12, 2006
    Publication date: June 8, 2006
    Inventors: Sei-Hyung Ryu, Anant Agarwal, Allan Ward
  • Publication number: 20060054895
    Abstract: Edge termination for silicon carbide devices has a plurality of concentric floating guard rings in a silicon carbide layer that are adjacent and spaced apart from a silicon carbide-based semiconductor junction. An insulating layer, such as an oxide, is provided on the floating guard rings and a silicon carbide surface charge compensation region is provided between the floating guard rings and is adjacent the insulating layer. Methods of fabricating such edge termination are also provided.
    Type: Application
    Filed: November 8, 2005
    Publication date: March 16, 2006
    Inventors: Sei-Hyung Ryu, Anant Agarwal