Patents by Inventor Qingchun Zhang

Qingchun Zhang 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: 20120319133
    Abstract: A thyristor includes a first conductivity type semiconductor layer, a first conductivity type carrier injection layer on the semiconductor layer, a second conductivity type drift layer on the carrier injection layer, a first conductivity type base layer on the drift layer, and a second conductivity type anode region on the base layer. The thickness and doping concentration of the carrier injection layer are selected to reduce minority carrier injection by the carrier injection layer in response to an increase in operating temperature of the thyristor. A cross-over current density at which the thyristor shifts from a negative temperature coefficient of forward voltage to a positive temperature coefficient of forward voltage is thereby reduced.
    Type: Application
    Filed: May 1, 2012
    Publication date: December 20, 2012
    Inventor: Qingchun Zhang
  • Patent number: 8330244
    Abstract: A semiconductor device according to some embodiments includes a semiconductor layer having a first conductivity type and a surface in which an active region of the semiconductor device is defined. A plurality of spaced apart first doped regions are arranged within the active region. The plurality of first doped regions have a second conductivity type that is opposite the first conductivity type, have a first dopant concentration, and define a plurality of exposed portions of the semiconductor layer within the active region. The plurality of first doped regions are arranged as islands in the semiconductor layer. A second doped region in the semiconductor layer has the second conductivity type and has a second dopant concentration that is greater than the first dopant concentration.
    Type: Grant
    Filed: June 26, 2009
    Date of Patent: December 11, 2012
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Sei-Hyung Ryu, Anant Agarwal
  • Publication number: 20120292636
    Abstract: A negative bevel edge termination for a Silicon Carbide (SiC) semiconductor device is disclosed. In one embodiment, the negative bevel edge termination includes multiple steps that approximate a smooth negative bevel edge termination at a desired slope. More specifically, in one embodiment, the negative bevel edge termination includes at least five steps, at least ten steps, or at least 15 steps. The desired slope is, in one embodiment, less than or equal to fifteen degrees. In one embodiment, the negative bevel edge termination results in a blocking voltage for the semiconductor device of at least 10 kilovolts (kV) or at least 12 kV. The semiconductor device is preferably, but not necessarily, a thyristor such as a power thyristor, a Bipolar Junction Transistor (BJT), an Insulated Gate Bipolar Transistor (IGBT), a U-channel Metal-Oxide-Semiconductor Field Effect Transistor (UMOSFET), or a PIN diode.
    Type: Application
    Filed: May 16, 2011
    Publication date: November 22, 2012
    Applicant: CREE, INC.
    Inventors: Qingchun Zhang, Craig Capell, Anant Agarwal, Sei-Hyung Ryu
  • Patent number: 8304783
    Abstract: Hybrid semiconductor devices including a PIN diode portion and a Schottky diode portion are provided. The PIN diode portion is provided on a semiconductor substrate and has an anode contact on a first surface of the semiconductor substrate. The Schottky diode portion is also provided on the semiconductor substrate and includes a polysilicon layer on the semiconductor substrate and a ohmic contact on the polysilicon layer. Related Schottky diodes are also provided herein.
    Type: Grant
    Filed: June 3, 2009
    Date of Patent: November 6, 2012
    Assignee: Cree, Inc.
    Inventors: Saptharishi Sriram, Qingchun Zhang
  • Publication number: 20120273802
    Abstract: An electronic device includes a silicon carbide drift region having a first conductivity type, a Schottky contact on the drift region, and a plurality of junction barrier Schottky (JBS) regions at a surface of the drift region adjacent the Schottky contact. The JBS regions have a second conductivity type opposite the first conductivity type and have a first spacing between adjacent ones of the JBS regions. The device further includes a plurality of surge protection subregions having the second conductivity type. Each of the surge protection subregions has a second spacing between adjacent ones of the surge protection subregions that is less than the first spacing.
    Type: Application
    Filed: July 11, 2012
    Publication date: November 1, 2012
    Inventors: Qingchun Zhang, Sei-Hyung Ryu
  • Patent number: 8294507
    Abstract: An electronic device includes a wide bandgap thyristor having an anode, a cathode, and a gate terminal, and a wide bandgap bipolar transistor having a base, a collector, and an emitter terminal. The emitter terminal of the bipolar transistor is directly coupled to the anode terminal of the thyristor such that the bipolar transistor and the thyristor are connected in series. The bipolar transistor and the thyristor define a wide bandgap bipolar power switching device that is configured to switch between a nonconducting state and a conducting state that allows current flow between a first main terminal corresponding to the collector terminal of the bipolar transistor and a second main terminal corresponding to the cathode terminal of the thyristor responsive to application of a first control signal to the base terminal of the bipolar transistor and responsive to application of a second control signal to the gate terminal of the thyristor. Related control circuits are also discussed.
    Type: Grant
    Filed: May 8, 2009
    Date of Patent: October 23, 2012
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, James Theodore Richmond, Robert J. Callanan
  • Patent number: 8288220
    Abstract: A method of forming a semiconductor device may include forming a terminal region of a first conductivity type within a semiconductor layer of the first conductivity type. A well region of a second conductivity type may be formed within the semiconductor layer wherein the well region is adjacent at least portions of the terminal region within the semiconductor layer, a depth of the well region into the semiconductor layer may be greater than a depth of the terminal region into the semiconductor layer, and the first and second conductivity types may be different. An epitaxial semiconductor layer may be formed on the semiconductor layer, and a terminal contact region of the first conductivity type may be formed in the epitaxial semiconductor layer with the terminal contact region providing electrical contact with the terminal region. In addition, an ohmic contact may be formed on the terminal contact region. Related structures are also discussed.
    Type: Grant
    Filed: March 27, 2009
    Date of Patent: October 16, 2012
    Assignee: Cree, Inc.
    Inventors: Brett Adam Hull, Qingchun Zhang
  • Publication number: 20120256192
    Abstract: An electronic device includes a drift region, a Schottky contact on a surface of the drift region, and an edge termination structure in the drift region adjacent the Schottky contact. The edge termination structure includes a recessed region that is recessed from the surface of the drift region by a distance d that may be about 0.5 microns.
    Type: Application
    Filed: April 5, 2011
    Publication date: October 11, 2012
    Inventors: Qingchun Zhang, Jason Henning
  • Publication number: 20120235164
    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: May 29, 2012
    Publication date: September 20, 2012
    Applicant: CREE, INC.
    Inventors: Qingchun Zhang, Anant Agarwal, Charlotte Jonas
  • Publication number: 20120205666
    Abstract: An electronic device includes a semiconductor layer, a primary junction in the semiconductor layer, a lightly doped region surrounding the primary junction and a junction termination structure in the lightly doped region adjacent the primary junction. The junction termination structure has an upper boundary, a side boundary, and a corner between the upper boundary and the side boundary, and the lightly doped region extends in a first direction away from the primary junction and normal to a point on the upper boundary by a first distance that is smaller than a second distance by which the lightly doped region extends in a second direction away from the primary junction and normal to a point on the corner. At least one floating guard ring segment may be provided in the semiconductor layer outside the corner of the junction termination structure. Related methods are also disclosed.
    Type: Application
    Filed: February 10, 2011
    Publication date: August 16, 2012
    Inventors: Jason Henning, Qingchun Zhang, Sei-Hyung Ryu
  • Patent number: 8232558
    Abstract: An electronic device includes a silicon carbide drift region having a first conductivity type, a Schottky contact on the drift region, and a plurality of junction barrier Schottky (JBS) regions at a surface of the drift region adjacent the Schottky contact. The JBS regions have a second conductivity type opposite the first conductivity type and have a first spacing between adjacent ones of the JBS regions. The device further includes a plurality of surge protection subregions having the second conductivity type. Each of the surge protection subregions has a second spacing between adjacent ones of the surge protection subregions that is less than the first spacing.
    Type: Grant
    Filed: May 21, 2008
    Date of Patent: July 31, 2012
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Sei-Hyung Ryu
  • Patent number: 8211770
    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: Grant
    Filed: June 24, 2011
    Date of Patent: July 3, 2012
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Anant Agarwal, Charlotte Jonas
  • Patent number: 8193848
    Abstract: Semiconductor switching devices include a wide band-gap power transistor, a wide band-gap surge current transistor that coupled in parallel to the power transistor, and a wide band-gap driver transistor that is configured to drive the surge current transistor. Substantially all of the on-state output current of the semiconductor switching device flows through the channel of the power transistor when a drain-source voltage of the power transistor is within a first voltage range, which range may correspond, for example, to the drain-source voltages expected during normal operation. In contrast, the semiconductor switching device is further configured so that in the on-state the output current flows through both the surge current transistor and the channel of the power transistor when the drain-source voltage of the power transistor is within a second, higher voltage range.
    Type: Grant
    Filed: November 2, 2009
    Date of Patent: June 5, 2012
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, James Theodore Richmond, Anant K. Agarwal, Sei-Hyung Ryu
  • Publication number: 20120122305
    Abstract: An electronic device includes a drift layer having a first conductivity type, a buffer layer having a second conductivity type, opposite the first conductivity type, on the drift layer and forming a P-N junction with the drift layer, and a junction termination extension region having the second conductivity type in the drift layer adjacent the P-N junction. The buffer layer includes a step portion that extends over a buried portion of the junction termination extension. Related methods are also disclosed.
    Type: Application
    Filed: December 28, 2011
    Publication date: May 17, 2012
    Inventors: Qingchun Zhang, Anant K. Agarwal
  • Publication number: 20120018737
    Abstract: Electronic device structures that compensate for non-uniform etching on a semiconductor wafer and methods of fabricating the same are disclosed. In one embodiment, the electronic device includes a number of layers including a semiconductor base layer of a first doping type formed of a desired semiconductor material, a semiconductor buffer layer on the base layer that is also formed of the desired semiconductor material, and one or more contact layers of a second doping type on the buffer layer. The one or more contact layers are etched to form a second contact region of the electronic device. The buffer layer reduces damage to the semiconductor base layer during fabrication of the electronic device. Preferably, a thickness of the semiconductor buffer layer is selected to compensate for over-etching due to non-uniform etching on a semiconductor wafer on which the electronic device is fabricated.
    Type: Application
    Filed: July 21, 2010
    Publication date: January 26, 2012
    Applicant: Cree, Inc.
    Inventors: Qingchun Zhang, Anant Agarwal
  • Publication number: 20120018738
    Abstract: Electronic device structures including semiconductor ledge layers for surface passivation and methods of manufacturing the same are disclosed. In one embodiment, the electronic device includes a number of semiconductor layers of a desired semiconductor material having alternating doping types. The semiconductor layers include a base layer of a first doping type that includes a highly doped well forming a first contact region of the electronic device and one or more contact layers of a second doping type on the base layer that have been etched to form a second contact region of the electronic device. The etching of the one or more contact layers causes substantial crystalline damage, and thus interface charge, on the surface of the base layer. In order to passivate the surface of the base layer, a semiconductor ledge layer of the semiconductor material is epitaxially grown on at least the surface of the base layer.
    Type: Application
    Filed: July 26, 2010
    Publication date: January 26, 2012
    Applicant: CREE, INC.
    Inventors: Qingchun Zhang, Anant Agarwal
  • Patent number: 8097919
    Abstract: An electronic device includes a drift layer having a first conductivity type, a buffer layer having a second conductivity type, opposite the first conductivity type, on the drift layer and forming a P?N junction with the drift layer, and a junction termination extension region having the second conductivity type in the drift layer adjacent the P?N junction. The buffer layer includes a step portion that extends over a buried portion of the junction termination extension. Related methods are also disclosed.
    Type: Grant
    Filed: August 11, 2008
    Date of Patent: January 17, 2012
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Anant K. Agarwal
  • Publication number: 20110254010
    Abstract: Semiconductor switching devices include a first wide band-gap semiconductor layer having a first conductivity type. First and second wide band-gap well regions that have a second conductivity type that is opposite the first conductivity type are provided on the first wide band-gap semiconductor layer. A non-wide band-gap semiconductor layer having the second conductivity type is provided on the first wide band-gap semiconductor layer. First and second wide band-gap source/drain regions that have the first conductivity type are provided on the first wide band-gap well region. A gate insulation layer is provided on the non-wide band-gap semiconductor layer, and a gate electrode is provided on the gate insulation layer.
    Type: Application
    Filed: April 16, 2010
    Publication date: October 20, 2011
    Inventor: Qingchun Zhang
  • Publication number: 20110250737
    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: June 24, 2011
    Publication date: October 13, 2011
    Applicant: CREE, INC.
    Inventors: Qingchun Zhang, Anant Agarwal, Charlotte Jonas
  • Publication number: 20110248285
    Abstract: A semiconductor device includes a semiconductor layer having a first conductivity type and having a surface in which an active region of the semiconductor device is defined, and a plurality of spaced apart doped regions within the active region. The plurality of doped regions have a second conductivity type that is opposite the first conductivity type and define a plurality of exposed portions of the semiconductor layer within the active region. The plurality of doped regions include a plurality of rows extending in a longitudinal direction. Each of the rows includes a plurality of longitudinally extending segments, and the longitudinally extending segments in a first row at least partially overlap the longitudinally extending segments in an adjacent row in a lateral direction that is perpendicular to the longitudinal direction.
    Type: Application
    Filed: March 18, 2011
    Publication date: October 13, 2011
    Inventors: Qingchun Zhang, Jason Honning