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: 20170345891
    Abstract: Semiconductor devices include a silicon carbide drift region having an upper portion and a lower portion. A first contact is on the upper portion of the drift region and a second contact is on the lower portion of the drift region. The drift region includes a superjunction structure that includes a p-n junction that is formed at an angle of between 10° and 30° from a plane that is normal to a top surface of the drift region. The p-n junction extends within +/?1.5° of a crystallographic axis of the silicon carbide material forming the drift region.
    Type: Application
    Filed: May 31, 2016
    Publication date: November 30, 2017
    Inventors: Edward Robert Van Brunt, Alexander V. Suvorov, Vipindas Pala, Daniel J. Lichtenwalner, Qingchun Zhang
  • Patent number: 9831355
    Abstract: The present disclosure relates to a Schottky diode having a drift layer and a Schottky layer. The drift layer is predominantly doped with a doping material of a first conductivity type and has a first surface associated with an active region. The Schottky layer is provided over the active region of the first surface to form a Schottky junction. A plurality of junction barrier elements are formed in the drift layer below the Schottky junction, and a plurality of central implants are also formed in the drift layer below the Schottky junction. In certain embodiments, at least one central implant is provided between each adjacent pair of junction barrier elements.
    Type: Grant
    Filed: March 28, 2016
    Date of Patent: November 28, 2017
    Assignee: Cree, Inc.
    Inventor: Qingchun Zhang
  • Publication number: 20170263713
    Abstract: A power module is disclosed that includes a housing with an interior chamber wherein multiple switch modules are mounted within the interior chamber. The switch modules comprise multiple transistors and diodes that are interconnected to facilitate switching power to a load. In one embodiment, at least one of the switch modules supports a current density of at least 10 amperes per cm2.
    Type: Application
    Filed: April 10, 2017
    Publication date: September 14, 2017
    Inventors: Jason Patrick Henning, Qingchun Zhang, Sei-Hyung Ryu, Anant Kumar Agarwal, John Williams Palmour, Scott Allen
  • Patent number: 9673283
    Abstract: A power module is disclosed that includes a housing with an interior chamber wherein multiple switch modules are mounted within the interior chamber. The switch modules comprise multiple transistors and diodes that are interconnected to facilitate switching power to a load. In one embodiment, at least one of the switch modules supports a current density of at least 10 amperes per cm2.
    Type: Grant
    Filed: August 17, 2012
    Date of Patent: June 6, 2017
    Assignee: Cree, Inc.
    Inventors: Jason Patrick Henning, Qingchun Zhang, Sei-Hyung Ryu, Anant Kumar Agarwal, John Williams Palmour, Scott Allen
  • Patent number: 9640652
    Abstract: A semiconductor device may include a semiconductor layer having a first conductivity type, a well region of a second conductivity type in the semiconductor layer wherein the first and second conductivity types are different, and a terminal region of the first conductivity type in the well region. An epitaxial semiconductor layer may be on the surface of the semiconductor layer including the well region and the terminal region with the epitaxial semiconductor layer having the first conductivity type across the well and terminal regions. A gate electrode may be on the epitaxial semiconductor layer so that the epitaxial semiconductor layer is between the gate electrode and portions of the well region surrounding the terminal region at the surface of the semiconductor layer.
    Type: Grant
    Filed: September 10, 2012
    Date of Patent: May 2, 2017
    Assignee: Cree, Inc.
    Inventors: Brett Adam Hull, Qingchun Zhang
  • Patent number: 9640609
    Abstract: Edge termination structures for semiconductor devices are provided including a plurality of spaced apart concentric floating guard rings in a semiconductor layer that at least partially surround a semiconductor junction. The spaced apart concentric floating guard rings have a highly doped portion and a lightly doped portion. Related methods of fabricating devices are also provided herein.
    Type: Grant
    Filed: February 26, 2008
    Date of Patent: May 2, 2017
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Charlotte Jonas, Anant K. Agarwal
  • Patent number: 9601605
    Abstract: A bipolar junction transistor (BJT), which includes a collector layer, a base layer on the collector layer, an emitter layer on the base layer, and a recess region embedded in the collector layer, is disclosed. A base-collector plane is between the base layer and the collector layer. The recess region is may be below the base-collector plane. Further, the recess region and the base layer are a first type of semiconductor material. By embedding the recess region in the collector layer, the recess region and the collector layer form a first P-N junction, which may provide a point of avalanche for the BJT. Further, the collector layer and the base layer form a second P-N junction. By separating the point of avalanche from the second P-N junction, the BJT may avalanche robustly, thereby reducing the likelihood of avalanche induced failures, particularly in silicon carbide (SiC) BJTs.
    Type: Grant
    Filed: April 4, 2012
    Date of Patent: March 21, 2017
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Anant K. Agarwal, Lin Cheng
  • Patent number: 9595618
    Abstract: An electronic device includes a silicon carbide layer including an n-type drift region therein, a contact forming a junction, such as a Schottky junction, with the drift region, and a p-type junction barrier region on the silicon carbide layer. The p-type junction barrier region includes a p-type polysilicon region forming a P-N heterojunction with the drift region, and the p-type junction barrier region is electrically connected to the contact. Related methods are also disclosed.
    Type: Grant
    Filed: September 29, 2014
    Date of Patent: March 14, 2017
    Assignee: Cree, Inc.
    Inventor: Qingchun Zhang
  • Publication number: 20170053987
    Abstract: A transistor device having reduced electrical field at the gate oxide interface is disclosed. In one embodiment, the transistor device comprises a gate, a source, and a drain, wherein the gate is at least partially in contact with a gate oxide. The transistor device has a P+ region within a JFET region of the transistor device in order to reduce an electrical field on the gate oxide.
    Type: Application
    Filed: November 7, 2016
    Publication date: February 23, 2017
    Inventors: Qingchun Zhang, Brett Hull
  • Patent number: 9570560
    Abstract: An electronic device includes a silicon carbide layer having a first conductivity type and a main junction adjacent a surface of the silicon carbide layer, and a junction termination region at the surface of the silicon carbide layer adjacent the main junction. Charge in the junction termination region decreases with lateral distance from the main junction, and a maximum charge in the junction termination region may be less than about 2×1014 cm?2.
    Type: Grant
    Filed: December 11, 2013
    Date of Patent: February 14, 2017
    Assignees: Cree, Inc., The University of South Carolina
    Inventors: Qingchun Zhang, Anant K. Agarwal, Tangali S. Sudarshan, Alexander Bolotnikov
  • Patent number: 9552997
    Abstract: Methods of forming a p-channel MOS device in silicon carbide include forming an n-type well in a silicon carbide layer, and implanting p-type dopant ions to form a p-type region in the n-type well at a surface of the silicon carbide layer and at least partially defining a channel region in the n-type well adjacent the p-type region. A threshold adjustment region is formed in the channel region. The implanted ions are annealed in an inert atmosphere at a temperature greater than 1650° C. A gate oxide layer is formed on the channel region, and a gate is formed on the gate oxide layer. A silicon carbide-based transistor includes a silicon carbide layer, an n-type well in the silicon carbide layer, and a p-type region in the n-type well at a surface of the silicon carbide layer and at least partially defining a channel region in the n-type well adjacent the p-type region.
    Type: Grant
    Filed: February 2, 2011
    Date of Patent: January 24, 2017
    Assignee: Cree, Inc.
    Inventors: Mrinal Kanti Das, Qingchun Zhang, Sei-Hyung Ryu
  • Patent number: 9548374
    Abstract: A method of forming a transistor device include forming a drift layer of a first conductivity type, forming a well of a second conductivity type in the drift layer, forming a JFET region with first conductivity type dopant ions in the drift layer, forming a channel adjustment layer of the first conductivity type on the JFET region and the well, implanting first conductivity type dopant ions to form an emitter region of the first conductivity type extending through the channel adjustment layer and into the well, wherein the emitter region is spaced apart from the JFET region by the well, implanting second conductivity type dopant ions to form a connector region of the second conductivity type adjacent the emitter region, forming a gate oxide layer on the channel region, and forming a gate on the gate oxide layer.
    Type: Grant
    Filed: April 24, 2014
    Date of Patent: January 17, 2017
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Sei-Hyung Ryu, Charlotte Jonas, Anant K. Agarwal
  • Patent number: 9530844
    Abstract: A transistor device having reduced electrical field at the gate oxide interface is disclosed. In one embodiment, the transistor device comprises a gate, a source, and a drain, wherein the gate is at least partially in contact with a gate oxide. The transistor device has a P+ region within a JFET region of the transistor device in order to reduce an electrical field on the gate oxide.
    Type: Grant
    Filed: December 28, 2012
    Date of Patent: December 27, 2016
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Brett Hull
  • Patent number: 9478537
    Abstract: A packaged power electronic device includes a wide bandgap bipolar driver transistor having a base, a collector, and an emitter terminal, and a wide bandgap bipolar output transistor having a base, a collector, and an emitter terminal. The collector terminal of the output transistor is coupled to the collector terminal of the driver transistor, and the base terminal of the output transistor is coupled to the emitter terminal of the driver transistor to provide a Darlington pair. An area of the output transistor is at least 3 times greater than an area of the driver transistor in plan view. For example, an area ratio of the output transistor to the driver transistor may be between about 3:1 to about 5:1. Related devices and methods of fabrication are also discussed.
    Type: Grant
    Filed: July 15, 2009
    Date of Patent: October 25, 2016
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Anant K. Agarwal
  • Patent number: 9466674
    Abstract: An electronic device includes a silicon carbide layer including an n-type drift region therein, a contact forming a Schottky junction with the drift region, and a p-type junction barrier region on the silicon carbide layer. The p-type junction barrier region includes a p-type polysilicon region forming a P-N heterojunction with the drift region, and the p-type junction barrier region is electrically connected to the contact.
    Type: Grant
    Filed: September 6, 2012
    Date of Patent: October 11, 2016
    Assignee: Cree, Inc.
    Inventors: Scott Thomas Allen, Qingchun Zhang
  • Patent number: 9431525
    Abstract: An IGBT device includes a drift region, a collector contact, an injector region, a pair of junction implants, a gate contact, and an emitter contact. The injector region includes a first surface in contact with the collector contact, a second surface opposite the first surface and in contact with the drift region, and at least one bypass region running between the first surface and the second surface. Notably, the at least one bypass region has a charge carrier that is different from that of the injector region. The pair of junction implants is in the drift region along a surface of the drift region opposite the injector region. The gate contact and the emitter contact are on the surface of the drift region opposite the injector region.
    Type: Grant
    Filed: June 12, 2014
    Date of Patent: August 30, 2016
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Qingchun Zhang
  • Publication number: 20160211387
    Abstract: The present disclosure relates to a Schottky diode having a drift layer and a Schottky layer. The drift layer is predominantly doped with a doping material of a first conductivity type and has a first surface associated with an active region. The Schottky layer is provided over the active region of the first surface to form a Schottky junction. A plurality of junction barrier elements are formed in the drift layer below the Schottky junction, and a plurality of central implants are also formed in the drift layer below the Schottky junction. In certain embodiments, at least one central implant is provided between each adjacent pair of junction barrier elements.
    Type: Application
    Filed: March 28, 2016
    Publication date: July 21, 2016
    Inventor: Qingchun Zhang
  • Patent number: 9385182
    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: Grant
    Filed: July 8, 2014
    Date of Patent: July 5, 2016
    Assignee: Cree, Inc.
    Inventors: Jason Henning, Qingchun Zhang, Sei-Hyung Ryu
  • Publication number: 20160133777
    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 drill 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: October 26, 2015
    Publication date: May 12, 2016
    Inventor: Qingchun Zhang
  • Patent number: 9337268
    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: Grant
    Filed: May 16, 2011
    Date of Patent: May 10, 2016
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Craig Capell, Anant Agarwal, Sei-Hyung Ryu