Patents by Inventor Umamaheswara VEMULAPATI
Umamaheswara VEMULAPATI 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).
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Patent number: 11967638Abstract: A power diode comprises a plurality of diode cells (10). Each diode cell (10) comprises a first conductivity type first anode layer (40), a first conductivity type second anode layer (45) having a lower doping concentration than the first anode layer (40) and being separated from an anode electrode layer (20) by the first anode layer (40), a second conductivity type drift layer (50) forming a pn-junction with the second anode layer (45), a second conductivity type cathode layer (60) being in direct contact with the cathode electrode layer (60), and a cathode-side segmentation layer (67) being in direct contact with the cathode electrode layer (30). A material of the cathode-side segmentation layer (67) is a first conductivity type semiconductor, wherein an integrated doping content of the cathode-side, which is integrated along a direction perpendicular to the second main side (102), is below 2·1013 cm?2, or a material of the cathode-side segmentation layer (67) is an insulating material.Type: GrantFiled: April 1, 2020Date of Patent: April 23, 2024Assignee: Hitachi Energy LtdInventors: Tobias Wikstroem, Umamaheswara Vemulapati, Thomas Stiasny
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Publication number: 20240038880Abstract: A bidirectional thyristor device (1) comprising a semiconductor body (2) extending between a first main surface (21) and a second main surface (22), is provided wherein a first main electrode (31) and a first gate electrode (41) are arranged on the first main surface and a second main electrode (32) and a second gate electrode (42) are arranged on the second main surface. The first main electrode comprises a plurality of first segments (310) that are spaced apart from one another, wherein at least some of the first segments are completely surrounded by the first gate electrode in a view onto the first main surface. The second main electrode comprises a plurality of second segments (320) that are spaced apart from one another, wherein at least some of the second segments are completely surrounded by the second gate electrode in a view onto the second main surface.Type: ApplicationFiled: November 22, 2021Publication date: February 1, 2024Inventors: Jan VOBECKY, Umamaheswara VEMULAPATI
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Patent number: 11824091Abstract: An integrated gate-commutated thyristor (IGCT) includes a semiconductor wafer having a first main side and a second main side opposite to the first main side and a plurality of first type thyristor cells and second type thyristor cells. The cathode electrode of the first type thyristor cells forms an ohmic contact with the cathode region and the cathode electrode of the second type thyristor cells is insulated from the cathode region. A predefined percentage of second type thyristor cells of the overall amount of first type thyristor cells and second type thyristor cells in a segment ring is greater than 0% and less than or equal to 75%.Type: GrantFiled: February 22, 2021Date of Patent: November 21, 2023Assignee: Hitachi Energy Switzerland AGInventors: Tobias Wikstroem, Umamaheswara Vemulapati
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Publication number: 20230317818Abstract: Disclosed is a power semiconductor device comprising a semiconductor wafer having a first main side and second main side. The semiconductor wafer comprises parallel thyristor cells, which each comprises (a) a cathode electrode and gate electrode on the first main side; (b) a cathode layer comprising a cathode region of a first conductivity type, forming an ohmic contact with the cathode electrode; (c) a first base layer of a second conductivity type, wherein the cathode region forms a p-n junction between the first base layer and cathode region; (d) a second base layer of the first conductivity type forming a second p-n junction with the first base layer; (e) an anode layer of the second conductivity type separated from the first base layer by the second base layer. The gate electrodes of the plurality of thyristor cells form a gate design comprising multiple polygons each comprising at least four struts.Type: ApplicationFiled: August 19, 2021Publication date: October 5, 2023Inventors: Jan VOBECKY, Umamaheswara VEMULAPATI
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Publication number: 20230111333Abstract: An integrated gate-commutated thyristor (IGCT) includes a semiconductor wafer having a first main side and a second main side opposite to the first main side and a plurality of first type thyristor cells and second type thyristor cells. The cathode electrode of the first type thyristor cells forms an ohmic contact with the cathode region and the cathode electrode of the second type thyristor cells is insulated from the cathode region. A predefined percentage of second type thyristor cells of the overall amount of first type thyristor cells and second type thyristor cells in a segment ring is greater than 0% and less than or equal to 75%.Type: ApplicationFiled: February 22, 2021Publication date: April 13, 2023Inventors: Tobias Wikstroem, Umamaheswara Vemulapati
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Publication number: 20230046742Abstract: A reverse conducting power semiconductor device includes a plurality of thyristor cells and a freewheeling diode are integrated in a semiconductor wafer. The freewheeling diode includes a diode anode layer, a diode anode electrode, a diode cathode layer, and a diode cathode electrode. The diode cathode layer includes diode cathode layer segments, each of which is stripe-shaped and arranged within a corresponding stripe-shaped first diode anode layer segment such that a longitudinal main axis of each diode cathode layer segment extends along the longitudinal main axis of the corresponding one of the first diode anode layer segments.Type: ApplicationFiled: February 3, 2021Publication date: February 16, 2023Inventors: Tobias Wikstroem, Umamaheswara Vemulapati
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Publication number: 20220393023Abstract: An insulated gate bipolar transistor includes a source electrode, a collector electrode, a source layer, a base layer, a drift layer and a collector layer. Trench gate electrodes extend through the base layer into the drift layer. A channel is located between the source layer, the base layer and the drift layer. A trench Schottky electrode is adjacent to one of the trench gate electrodes and includes an electrically conductive Schottky layer arranged lateral to the base layer and extends through the base layer into the drift layer. The Schottky layer is electrically connected to the source electrode. Collection areas are located in the drift layer at a respective trench gate electrode bottom of the trench gate electrodes or of the trench Schottky electrode. The Schottky layer forms a Schottky contact to the collection area at a contact area.Type: ApplicationFiled: November 6, 2020Publication date: December 8, 2022Inventors: Florin Udrea, Marina Antoniou, Neophytos Lophitis, Chiara Corvasce, Luca De-Michielis, Umamaheswara Vemulapati, Uwe Badstuebner, Munaf Rahimo
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Publication number: 20220181473Abstract: A power diode comprises a plurality of diode cells (10). Each diode cell (10) comprises a first conductivity type first anode layer (40), a first conductivity type second anode layer (45) having a lower doping concentration than the first anode layer (40) and being separated from an anode electrode layer (20) by the first anode layer (40), a second conductivity type drift layer (50) forming a pn-junction with the second anode layer (45), a second conductivity type cathode layer (60) being in direct contact with the cathode electrode layer (60), and a cathode-side segmentation layer (67) being in direct contact with the cathode electrode layer (30). A material of the cathode-side segmentation layer (67) is a first conductivity type semiconductor, wherein an integrated doping content of the cathode-side, which is integrated along a direction perpendicular to the second main side (102), is below 2·1013 cm?2, or a material of the cathode-side segmentation layer (67) is an insulating material.Type: ApplicationFiled: April 1, 2020Publication date: June 9, 2022Inventors: Tobias Wikstroem, Umamaheswara Vemulapati, Thomas Stiasny
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Patent number: 11107740Abstract: A power semiconductor module including at least one power semiconductor chip providing a power electronics switch; and a semiconductor wafer, to which the at least one power semiconductor chip is bonded; wherein the semiconductor wafer is doped, such that it includes a field blocking region and an electrically conducting region on the field blocking region, to which electrically conducting region the at least one power semiconductor chip is bonded.Type: GrantFiled: August 2, 2017Date of Patent: August 31, 2021Assignee: ABB Power Grids Switzerland AGInventors: Jürgen Schuderer, Umamaheswara Vemulapati, Marco Bellini, Jan Vobecky
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Patent number: 11056582Abstract: A bidirectional thyristor device includes a semiconductor wafer with a number of layers forming pn junctions. A first main electrode and a first gate electrode are arranged on a first main side of the wafer. A second main electrode and a second gate electrode are arranged on a second main side of the wafer. First emitter shorts penetrate through a first semiconductor layer and second emitter shorts penetrate through a fifth semiconductor layer. In an orthogonal projection onto a plane parallel to the first main side, a first area occupied by the first semiconductor layer and the first emitter shorts overlaps in an overlapping area with a second area occupied by the fifth semiconductor layer and the second emitter shorts. The overlapping area, in which the first area overlaps with the second area, encompasses at least 50% of a total wafer area occupied by the semiconductor wafer.Type: GrantFiled: February 13, 2019Date of Patent: July 6, 2021Assignee: ABB Power Grids Switzerland AGInventors: Jan Vobecky, Umamaheswara Vemulapati, Munaf Rahimo
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Patent number: 11043943Abstract: A semiconductor module comprises reverse conducting IGBT connected in parallel with a wide bandgap MOSFET, wherein each of the reverse conducting IGBT and the wide bandgap MOSFET comprises an internal anti-parallel diode. A method for operating a semiconductor module with the method including the steps of: determining a reverse conduction start time, in which the semiconductor module starts to conduct a current in a reverse direction, which reverse direction is a conducting direction of the internal anti-parallel diodes; applying a positive gate signal to the wide bandgap MOSFET after the reverse conduction start time; determining a reverse conduction end time based on the reverse conduction start time, in which the semiconductor module ends to conduct a current in the reverse direction; and applying a reduced gate signal to the wide bandgap MOSFET a blanking time interval before the reverse conduction end time, the reduced gate signal being adapted for switching the wide bandgap MOSFET into a blocking state.Type: GrantFiled: May 14, 2019Date of Patent: June 22, 2021Assignee: ABB Power Grids Switzerland AGInventors: Umamaheswara Vemulapati, Ulrich Schlapbach, Munaf Rahimo
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Patent number: 11031473Abstract: A power semiconductor device includes a semiconductor wafer having a first main side surface and a second main side surface. The semiconductor wafer includes a first semiconductor layer having a first conductivity type and a plurality of columnar or plate-shaped first semiconductor regions extending in the first semiconductor layer between the first main side surface and the second main side surface in a vertical direction perpendicular to the first main side surface and the second main side surface. The first semiconductor regions have a second conductivity type, which is different from the first conductivity type. Therein, the first semiconductor is a layer of hexagonal silicon carbide. The first semiconductor regions are regions of 3C polytype silicon carbide.Type: GrantFiled: September 3, 2019Date of Patent: June 8, 2021Assignee: ABB POWER GRIDS SWITZERLAND AGInventors: Friedhelm Bauer, Lars Knoll, Marco Bellini, Renato Minamisawa, Umamaheswara Vemulapati
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Publication number: 20200411674Abstract: A bidirectional thyristor device includes a semiconductor wafer with a number of layers forming pn junctions. A first main electrode and a first gate electrode are arranged on a first main side of the wafer. A second main electrode and a second gate electrode are arranged on a second main side of the wafer. First emitter shorts penetrate through a first semiconductor layer and second emitter shorts penetrate through a fifth semiconductor layer. In an orthogonal projection onto a plane parallel to the first main side, a first area occupied by the first semiconductor layer and the first emitter shorts overlaps in an overlapping area with a second area occupied by the fifth semiconductor layer and the second emitter shorts. The overlapping area, in which the first area overlaps with the second area, encompasses at least 50% of a total wafer area occupied by the semiconductor wafer.Type: ApplicationFiled: February 13, 2019Publication date: December 31, 2020Inventors: Jan Vobecky, Umamaheswara Vemulapati, Munaf Rahimo
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Patent number: 10629677Abstract: A high power semiconductor device with a floating field ring termination includes a wafer, wherein a plurality of floating field rings is formed in an edge termination region adjacent to a first main side surface of the wafer. At least in the termination region a drift layer, in which the floating field rings are formed, includes a surface layer and a bulk layer wherein the surface layer is formed adjacent to the first main side surface to separate the bulk layer from the first main side surface and has an average doping concentration which is less than 50% of the minimum doping concentration of the bulk layer. The drift layer includes a plurality of enhanced doping regions, wherein each one of the enhanced doping regions is in direct contact with a corresponding one of the floating field rings at least on a lateral side of this floating field ring, which faces towards the active region.Type: GrantFiled: May 29, 2018Date of Patent: April 21, 2020Assignee: ABB Schweiz AGInventors: Friedhelm Bauer, Umamaheswara Vemulapati
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Patent number: 10566463Abstract: In a power semiconductor device of the application a total number n of floating field rings (10_1 to 10_n) formed in a termination area is at least 10. For any integer i in a range from i=2 to i=n, a ring-to-ring separation di,i?i between an i-th floating field ring and a directly adjacent (i?1)-th floating field ring, when counting the floating field rings (10_1 to 10_n) along a straight line starting from a main pn-junction and extending in a lateral direction away from the main pn-junction, is given by the following formula: di,i?1=d1,0+?j=1j=i?1 ?j for i=2 to n, wherein d1,0 is a distance between the innermost floating field ring (10_1) closest to the main pn-junction and the main pn-junction, and wherein: ?zone1?0.05·?zone2<?j<?zone1+0.05·?zone2 for j=1 to I?2, 2·?zone2<|?j|<10·?zone2. for j=I?1, 0.95·?zone2<?j<1.05·?zone2 for j=I to n?1, ?zone2>0.1 ?m, and ??zone2/2<?zone1<?zone2/2, wherein I is an integer, for which 3?l?n/2.Type: GrantFiled: May 23, 2019Date of Patent: February 18, 2020Assignee: ABB SchweizInventors: Friedhelm Bauer, Umamaheswara Vemulapati, Marco Bellini
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Publication number: 20200006496Abstract: A power semiconductor device includes a semiconductor wafer having a first main side surface and a second main side surface. The semiconductor wafer includes a first semiconductor layer having a first conductivity type and a plurality of columnar or plate-shaped first semiconductor regions extending in the first semiconductor layer between the first main side surface and the second main side surface in a vertical direction perpendicular to the first main side surface and the second main side surface. The first semiconductor regions have a second conductivity type, which is different from the first conductivity type. Therein, the first semiconductor is a layer of hexagonal silicon carbide. The first semiconductor regions are regions of 3C polytype silicon carbide.Type: ApplicationFiled: September 3, 2019Publication date: January 2, 2020Inventors: Friedhelm Bauer, Lars Knoll, Marco Bellini, Renato Minamisawa, Umamaheswara Vemulapati
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Patent number: 10461157Abstract: The invention relates to a turn-off power semiconductor device comprising a plurality of thyristor cells, each thyristor cell comprising a cathode region; a base layer; a drift layer; an anode layer; a gate electrode which is arranged lateral to the cathode region in contact with the base layer; a cathode electrode; and an anode electrode. Interfaces between the cathode regions and the cathode electrodes as well as interfaces between the base layers and the gate electrodes of the plurality of thyristor cells are flat and coplanar.Type: GrantFiled: March 12, 2018Date of Patent: October 29, 2019Assignee: ABB Schweiz AGInventors: Martin Arnold, Umamaheswara Vemulapati
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Publication number: 20190288124Abstract: In a power semiconductor device of the application a total number n of floating field rings (10_1 to 10_n) formed in a termination area is at least 10. For any integer i in a range from i=2 to i=n, a ring-to-ring separation di,1?i between an i-th floating field ring and a directly adjacent (i?1)-th floating field ring, when counting the floating field rings (10_1 to 10_n) along a straight line starting from a main pn-junction and extending in a lateral direction away from the main pn-junction, is given by the following formula: di,i?1=d1,0+?j=1j=i?1 ?j for i=2 to n, wherein d1,0 is a distance between the innermost floating field ring (10_1) closest to the main pn-junction and the main pn-junction, and wherein: ?zone1?0.05·?zone2<?j<?zone1+0.05·?zone2 for j=1 to I-2, 2·?zone2<zone2<Aj<Azonel +0.05 A zone2 <|?j|<10·?zone2. for j=I?1, 0.95·?zone2<?j<1.05·?zone2 for j=I to n?1, ?zone2<0.1 ?m, and ??zone2/2 <?zone1<?zone2/2 , wherein I is an integer, for which 3?l?n/2.Type: ApplicationFiled: May 23, 2019Publication date: September 19, 2019Inventors: Friedhelm Bauer, Umamaheswara Vemulapati, Marco Bellini
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Publication number: 20190273493Abstract: A semiconductor module comprises reverse conducting IGBT connected in parallel with a wide bandgap MOSFET, wherein each of the reverse conducting IGBT and the wide bandgap MOSFET comprises an internal anti-parallel diode.Type: ApplicationFiled: May 14, 2019Publication date: September 5, 2019Inventors: Umamaheswara Vemulapati, Ulrich Schlapbach, Munaf Rahimo
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Publication number: 20190035884Abstract: A high power semiconductor device with a floating field ring termination includes a wafer, wherein a plurality of floating field rings is formed in an edge termination region adjacent to a first main side surface of the wafer. At least in the termination region a drift layer, in which the floating field rings are formed, includes a surface layer and a bulk layer wherein the surface layer is formed adjacent to the first main side surface to separate the bulk layer from the first main side surface and has an average doping concentration which is less than 50% of the minimum doping concentration of the bulk layer. The drift layer includes a plurality of enhanced doping regions, wherein each one of the enhanced doping regions is in direct contact with a corresponding one of the floating field rings at least on a lateral side of this floating field ring, which faces towards the active region.Type: ApplicationFiled: May 29, 2018Publication date: January 31, 2019Inventors: Friedhelm Bauer, Umamaheswara Vemulapati