Patents by Inventor Kijeong Han

Kijeong Han 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: 11843061
    Abstract: A power semiconductor device has a semiconductor layer structure that includes a silicon carbide drift region having a first conductivity type, first and second wells in the silicon carbide drift region that are doped with dopants having a second conductivity type, and a JFET region between the first and second wells. The first and second wells each include a main well and a side well that is between the main well and the JFET region, and each side well includes a respective channel region. A doping concentration of the JFET region exceeds a doping concentration of the silicon carbide drift region, and a minimum width of an upper portion of the JFET region is greater than a minimum width of a lower portion of the JFET region.
    Type: Grant
    Filed: August 27, 2020
    Date of Patent: December 12, 2023
    Assignee: Wolfspeed, Inc.
    Inventors: Kijeong Han, Joohyung Kim, Sei-Hyung Ryu
  • Patent number: 11769827
    Abstract: A transistor includes a substrate, a drift layer on the substrate, and a junction implant in the drift layer opposite the substrate. The junction implant includes a body well and a source well within the body well. A source contact is in electrical contact with the source well and the body well. A drain contact is in electrical contact with the substrate. A gate insulator is on the drift layer and over a portion of the body well and the source well. A gate contact is on the gate insulator. A softness of a body diode between the source contact and the drain contact is greater than 0.5. By providing the transistor such that the softness factor of the body diode is greater than 0.5, the switching performance of the body diode and thus switching losses of the transistor when used in a bidirectional conduction application will be significantly reduced.
    Type: Grant
    Filed: December 2, 2020
    Date of Patent: September 26, 2023
    Assignee: Wolfspeed, Inc.
    Inventors: Kijeong Han, Sei-Hyung Ryu, Daniel Jenner Lichtenwalner
  • Publication number: 20220416075
    Abstract: A vertical semiconductor device includes one or more of a substrate, a buffer layer over the substrate, one or more drift layers over the buffer layer, and a spreading layer over the one or more drift layers.
    Type: Application
    Filed: September 6, 2022
    Publication date: December 29, 2022
    Inventors: Daniel Jenner Lichtenwalner, Sei-Hyung Ryu, Kijeong Han, Edward Robert Van Brunt
  • Patent number: 11489069
    Abstract: A vertical semiconductor device includes one or more of a substrate, a buffer layer over the substrate, one or more drift layers over the buffer layer, and a spreading layer over the one or more drift layers.
    Type: Grant
    Filed: July 24, 2020
    Date of Patent: November 1, 2022
    Assignee: WOLFSPEED, INC.
    Inventors: Daniel Jenner Lichtenwalner, Sei-Hyung Ryu, Kijeong Han, Edward Robert Van Brunt
  • Publication number: 20220173238
    Abstract: A semiconductor device includes a vertical transistor and a body diode. Various improvements to the semiconductor device allow for improved performance of the body diode, in particular to reduced snappiness and increased softness.
    Type: Application
    Filed: March 22, 2021
    Publication date: June 2, 2022
    Inventors: Kijeong Han, Sei-Hyung Ryu, Daniel Jenner Lichtenwalner
  • Publication number: 20220173237
    Abstract: A transistor includes a substrate, a drift layer on the substrate, and a junction implant in the drift layer opposite the substrate. The junction implant includes a body well and a source well within the body well. A source contact is in electrical contact with the source well and the body well. A drain contact is in electrical contact with the substrate. A gate insulator is on the drift layer and over a portion of the body well and the source well. A gate contact is on the gate insulator. A softness of a body diode between the source contact and the drain contact is greater than 0.5. By providing the transistor such that the softness factor of the body diode is greater than 0.5, the switching performance of the body diode and thus switching losses of the transistor when used in a bidirectional conduction application will be significantly reduced.
    Type: Application
    Filed: December 2, 2020
    Publication date: June 2, 2022
    Inventors: Kijeong Han, Sei-Hyung Ryu, Daniel Jenner Lichtenwalner
  • Publication number: 20220069138
    Abstract: A power semiconductor device has a semiconductor layer structure that includes a silicon carbide drift region having a first conductivity type, first and second wells in the silicon carbide drift region that are doped with dopants having a second conductivity type, and a JFET region between the first and second wells. The first and second wells each include a main well and a side well that is between the main well and the JFET region, and each side well includes a respective channel region. A doping concentration of the JFET region exceeds a doping concentration of the silicon carbide drift region, and a minimum width of an upper portion of the JFET region is greater than a minimum width of a lower portion of the JFET region.
    Type: Application
    Filed: August 27, 2020
    Publication date: March 3, 2022
    Inventors: Kijeong Han, Joohyung Kim, Sei-Hyung Ryu
  • Publication number: 20210202341
    Abstract: Shielding techniques are used to provide an embedded sensor element such as a temperature sensing element on a wide bandgap power semiconductor device. A semiconductor device may include a drift layer and an embedded sensor element. The drift layer may be a wide bandgap semiconductor material. A shielding structure is provided in the drift layer below the embedded sensor element. The embedded sensor element may be provided between contacts that are in electrical contact with the shielding well. The distance between the contacts may be minimized. A noise reduction well may be provided between the contacts to further isolate the embedded sensor element from parasitic signals.
    Type: Application
    Filed: March 15, 2021
    Publication date: July 1, 2021
    Inventors: Joohyung Kim, Sei-Hyung Ryu, Kijeong Han, Thomas E. Harrington, III, Edward Robert Van Brunt
  • Publication number: 20200365721
    Abstract: A vertical semiconductor device includes one or more of a substrate, a buffer layer over the substrate, one or more drift layers over the buffer layer, and a spreading layer over the one or more drift layers.
    Type: Application
    Filed: July 24, 2020
    Publication date: November 19, 2020
    Inventors: Daniel Jenner Lichtenwalner, Sei-Hyung Ryu, Kijeong Han, Edward Robert Van Brunt
  • Patent number: 8653224
    Abstract: Provided is a composition for manufacturing a polyester resin having a molar ratio of a diol compound to a dicarboxylic acid compound ranging from 1.05 to 1.4, in which the composition includes 5 ppm to 50 ppm of a phosphorous (P) compound (based on an amount of P), 10 ppm to 40 ppm of a cobalt (Co) compound (based on an amount of Co), 0.2 ppm to 20 ppm of a color enhancer, and 5 ppm to 25 ppm/3 ppm to 30 ppm of a titanium (Ti)-germanium (Ge) composite catalyst compound (based on an amount of Ti/Ge), based on weight percentage.
    Type: Grant
    Filed: February 8, 2013
    Date of Patent: February 18, 2014
    Assignee: Lotte Chemical Corporation
    Inventors: Soomin Lee, Sanghyun Park, Joongeun Jung, Kijeong Han, Sungmin Hong, Yunbae Kook, Jeongsun Kim