Patents by Inventor Ulf Gustafsson

Ulf Gustafsson 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: 5977605
    Abstract: A semiconductor component, which comprises a pn junction, where both the p-conducting and the n-conducting layers of the pn junction constitute doped silicon carbide layers and where the edge of at least one of the conducting layers of the pn junction, exhibits a stepwise or uniformly decreasing total charge or effective surface charge density from the initial value at the defined working junction to a zero or almost zero total charge at the outermost edge of the junction following a radial direction from the central part of the junction towards the outermost edge.
    Type: Grant
    Filed: October 20, 1997
    Date of Patent: November 2, 1999
    Assignee: Asea Brown Boveri AB
    Inventors: Mietek Bakowsky, Bo Bijlenga, Ulf Gustafsson, Christopher Harris, Susan Savage
  • Patent number: 5967795
    Abstract: A semiconductor component comprises a pn junction in which both the p-conducting and the n-conducting layers of the pn junction are doped silicon carbide layers and the edge of at least one of the conducting layers of the pn junction exhibits a stepwise or uniformly decreasing total charge or effective surface charge density from the initial value at the defined working junction to a zero or almost zero total charge at the outermost edge of the junction following a radial direction from the central part of the junction towards its outermost edge.
    Type: Grant
    Filed: August 30, 1995
    Date of Patent: October 19, 1999
    Assignee: Asea Brown Boveri AB
    Inventors: Mietek Bakowsky, Bo Bijlenga, Ulf Gustafsson, Christopher Harris, Susan Savage
  • Patent number: 5932894
    Abstract: A semiconductor device of planar structure, comprises a pn junction, formed of a first type conducting layer and on top thereof a second type conducting layer, both layers of doped silicon carbide, the edge of the second of the layers being provided with an edge termination (JTE), enclosing stepwise or continuously decreasing effective sheet charge density towards the outer border of the termination, wherein the pn junction and its JTE are covered by a doped or undoped SiC third layer.
    Type: Grant
    Filed: June 26, 1997
    Date of Patent: August 3, 1999
    Assignee: ABB Research Ltd.
    Inventors: Mietek Bakowski, Ulf Gustafsson, Christopher I. Harris
  • Patent number: 5923051
    Abstract: A field controlled semiconductor device of SiC comprises superimposed in the order mentioned at least a drain (12), a highly doped substrate layer (1) and a low doped n-type drift layer (2). It has also a highly doped n-type source region layer (6) and a source (11) connected thereto. A doped channel region layer (4) connects the source region layer to the drift layer, and a current is intended to flow therethrough when the device is in an on-state. The device has also a gate electrode (9). The channel region layer has a substantially lateral extension and is formed by a low doped n-type layer (4). The gate electrode (9) is arranged to influence the channel region layer from above for giving a conducting channel (17) created therein from the source region layer to the drift layer a substantially lateral extension.
    Type: Grant
    Filed: October 17, 1997
    Date of Patent: July 13, 1999
    Assignee: ABB Research Ltd.
    Inventors: Christopher Harris, Mietek Bakowski, Ulf Gustafsson, Mats Andersson
  • Patent number: 5914500
    Abstract: A semiconductor diode structure with a Schottky junction, wherein a metal contact and a silicon carbide semiconductor layer of a first conducting type form the junction and wherein the edge of the junction exhibits a junction termination divided into a transition belt (TB) having gradually increasing total charge or effective sheet charge density closest to the metal contact and a Junction Termination Extension (JTE) outside the transition belt, the JTE having a charge profile with a stepwise or uniformly deceasing total charge or effective sheet charge density from an initial value to a zero or almost zero total charge at the outermost edge of the termination following a radial direction from the center part of the JTE towards the outermost edge of the termination.
    Type: Grant
    Filed: March 20, 1997
    Date of Patent: June 22, 1999
    Assignee: ABB Research Ltd.
    Inventors: Mietek Bakowski, Ulf Gustafsson
  • Patent number: 5909039
    Abstract: An IGBT comprises a drain, a highly doped p-type substrate layer, a highly doped n-type buffer layer, a drift layer, a p-type base layer, a highly doped n-type source region layer and a source electrode. A trench is etched in the base layer and an insulating layer with a gate electrode thereon is arranged on the base layer from the source region layer to the drift layer for the creation of a conducting inversion channel there. A contact portion is provided vertically separated from the source region layer and has the source electrode applied thereon for collecting holes injected from the substrate layer to the drift layer at a vertical distance from the source region layer.
    Type: Grant
    Filed: January 13, 1997
    Date of Patent: June 1, 1999
    Assignee: ABB Research Ltd.
    Inventors: Mietek Bakowski, Christopher Harris, Ulf Gustafsson
  • Patent number: 5831287
    Abstract: A bipolar semiconductor comprising layers of SiC semiconductor material. At least one pn-junction is formed between two of the layers having charged carrier transport across the junction when the device is in a conductive state. A resistive element in series with the pn-junction lowers the current through the pn-junction as the voltage drop across the device increases with an increase in temperature. The temperature coefficient for the device switches from a negative to a positive at a lower current through the device.
    Type: Grant
    Filed: September 4, 1996
    Date of Patent: November 3, 1998
    Assignee: ABB Research, Ltd.
    Inventors: Mietek Bakowski, Ulf Gustafsson, Henry Bleichner
  • Patent number: 5801836
    Abstract: A semiconductor component comprises a pn junction having a first conductivity type layer and a second conductivity type layer, both being doped layers of silicon carbide (SiC), the first conductivity type layer being lower doped and being provided with a depletion region stopper (DRS) located outside the pn junction, the DRS having stepwise or continuously increasing effective sheet charge density of the first conducting type in a radial direction towards the outer edge of the semiconductor component.
    Type: Grant
    Filed: July 16, 1996
    Date of Patent: September 1, 1998
    Assignee: ABB Research Ltd.
    Inventors: Mietek Bakowski, Ulf Gustafsson
  • Patent number: 5773849
    Abstract: A field controlled semiconductor device of SiC has a drain, a highly doped substrate layer on top of the drain and a low doped n-type drift layer on top of the substrate layer. A p-type base layer is located on the drift layer and a vertical trench extends through the base layer. In the trench an n-type channel region extends vertically along a wall of the trench and connects a source region layer to the drift layer. A gate electrode is arranged in the trench to be on the opposite side of the channel region with respect to the base layer.
    Type: Grant
    Filed: April 24, 1996
    Date of Patent: June 30, 1998
    Assignee: ABB Research Ltd.
    Inventors: Christopher Harris, Mietek Bakowski, Ulf Gustafsson, Mats Andersson
  • Patent number: 5763902
    Abstract: An insulated gate bipolar transistor comprises a drain which supports a highly doped p-type substrate layer; a low doped n-type drift layer supported over the substrate layer; a base layer supported over the drift layer including a trench extending into the base layer, and supporting an insulated gate on an upper surface thereof separated from the trench by a highly doped n-type source region, the trench having a highly doped p-type layer at the bottom thereof vertically separated from the source region; and a source layer disposed over the n-type source region and extending into the trench covering the highly doped p-type layer in the trench bottom, wherein an applied voltage to the gate forms a conducting inversion channel in the base layer for electron transport from the source region to the drain, and the highly doped p-type layer in the bottom of the trench collects holes injected from the substrate layer into the drift layer thereby improving latch up immunity for the transistor.
    Type: Grant
    Filed: April 24, 1996
    Date of Patent: June 9, 1998
    Assignee: ABB Research Ltd.
    Inventors: Christopher Harris, Ulf Gustafsson, Mietek Bakowski