Patents by Inventor Greg P. KLOWAK

Greg P. KLOWAK 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: 10283501
    Abstract: A GaN-on-Si device structure and a method of fabrication are disclosed for improved die yield and device reliability of high current/high voltage lateral GaN transistors. A plurality of conventional GaN device structures comprising GaN epi-layers are fabricated on a silicon substrate (GaN-on-Si die). After processing of on-chip interconnect layers, a trench structure is defined around each die, through the GaN epi-layers and into the silicon substrate. A trench cladding is provided on proximal sidewalls, comprising at least one of a passivation layer and a conductive metal layer. The trench cladding extends over exposed surfaces of the GaN epi-layers, over the interface region with the substrate, and also over the exposed surfaces of the interconnect layers. This structure reduces risk of propagation of dicing damage and defects or cracks in the GaN epi-layers into active device regions. A metal trench cladding acts as a barrier for electro-migration of mobile ions.
    Type: Grant
    Filed: March 2, 2017
    Date of Patent: May 7, 2019
    Assignee: GaN Systems Inc.
    Inventors: Thomas Macelwee, Greg P. Klowak, Howard Tweddle
  • Patent number: 10249506
    Abstract: A GaN-on-Si device structure and a method of fabrication are disclosed for improved die yield and device reliability of high current/high voltage lateral GaN transistors. A plurality of conventional GaN device structures comprising GaN epi-layers are fabricated on a silicon substrate (GaN-on-Si die). After processing of on-chip interconnect layers, a trench structure is defined around each die, through the GaN epi-layers and into the silicon substrate. A trench cladding is provided on proximal sidewalls, comprising at least one of a passivation layer and a conductive metal layer. The trench cladding extends over exposed surfaces of the GaN epi-layers, over the interface region with the substrate, and over the exposed surfaces of the interconnect layers. This structure reduces risk of propagation of dicing damage and defects or cracks in the GaN epi-layers into active device regions. A metal trench cladding acts as a barrier for electro-migration of mobile ions.
    Type: Grant
    Filed: September 22, 2017
    Date of Patent: April 2, 2019
    Inventors: Thomas Macelwee, Greg P. Klowak, Howard Tweddle
  • Publication number: 20190081623
    Abstract: Large area, high current, lateral GaN power transistors are implemented using an on-chip interconnect topology wherein the transistor is arranged as an array of sections, each section comprising a set of transistor islands; gate and source buses that form each gate drive loop have substantially the same track widths; the source bus runs over or under the gate bus, and the tracks are inductively coupled to provide flux cancellation in the gate drive loop, thereby reducing parasitic inductances. The gate delay in each gate drive loop is reduced, minimizing the gate drive phase difference across the transistor. An overlying current redistribution layer preferably has a track width no greater than that of the underlying source and drain buses, for efficient coupling. This topology provides improved scalability, enabling fabrication of multi-section, large scale, high current lateral GaN transistors with reduced gate drive loop inductance, for improved operational stability.
    Type: Application
    Filed: September 14, 2017
    Publication date: March 14, 2019
    Inventors: Ahmad MIZAN, Greg P. KLOWAK, Xiaodong CUI
  • Patent number: 10218346
    Abstract: Large area, high current, lateral GaN power transistors are implemented using an on-chip interconnect topology wherein the transistor is arranged as an array of sections, each section comprising a set of transistor islands; gate and source buses that form each gate drive loop have substantially the same track widths; the source bus runs over or under the gate bus, and the tracks are inductively coupled to provide flux cancellation in the gate drive loop, thereby reducing parasitic inductances. The gate delay in each gate drive loop is reduced, minimizing the gate drive phase difference across the transistor. An overlying current redistribution layer preferably has a track width no greater than that of the underlying source and drain buses, for efficient coupling. This topology provides improved scalability, enabling fabrication of multi-section, large scale, high current lateral GaN transistors with reduced gate drive loop inductance, for improved operational stability.
    Type: Grant
    Filed: September 14, 2017
    Date of Patent: February 26, 2019
    Assignee: GaN Systems Inc.
    Inventors: Ahmad Mizan, Greg P. Klowak, Xiaodong Cui
  • Publication number: 20180012770
    Abstract: A GaN-on-Si device structure and a method of fabrication are disclosed for improved die yield and device reliability of high current/high voltage lateral GaN transistors. A plurality of conventional GaN device structures comprising GaN epi-layers are fabricated on a silicon substrate (GaN-on-Si die). After processing of on-chip interconnect layers, a trench structure is defined around each die, through the GaN epi-layers and into the silicon substrate. A trench cladding is provided on proximal sidewalls, comprising at least one of a passivation layer and a conductive metal layer. The trench cladding extends over exposed surfaces of the GaN epi-layers, over the interface region with the substrate, and over the exposed surfaces of the interconnect layers. This structure reduces risk of propagation of dicing damage and defects or cracks in the GaN epi-layers into active device regions. A metal trench cladding acts as a barrier for electro-migration of mobile ions.
    Type: Application
    Filed: September 22, 2017
    Publication date: January 11, 2018
    Inventors: Thomas MACELWEE, Greg P. KLOWAK, Howard TWEDDLE
  • Patent number: 9824949
    Abstract: Packaging solutions for devices and systems comprising lateral GaN power transistors are disclosed, including components of a packaging assembly, a semiconductor device structure, and a method of fabrication thereof. In the packaging assembly, a GaN die, comprising one or more lateral GaN power transistors, is sandwiched between first and second leadframe layers, and interconnected using low inductance interconnections, without wirebonding. For thermal dissipation, the dual leadframe package assembly can be configured for either front-side or back-side cooling. Preferred embodiments facilitate alignment and registration of high current/low inductance interconnects for lateral GaN devices, in which contact areas or pads for source, drain and gate contacts are provided on the front-side of the GaN die.
    Type: Grant
    Filed: June 30, 2016
    Date of Patent: November 21, 2017
    Assignee: GaN Systems Inc.
    Inventors: Cameron McKnight-MacNeil, Greg P. Klowak, Ahmad Mizan, Stephen Coates
  • Patent number: 9818857
    Abstract: A fault tolerant design for large area nitride semiconductor devices is provided, which facilitates testing and isolation of defective areas. A transistor comprises an array of a plurality of islands, each island comprising an active region, source and drain electrodes, and a gate electrode. Electrodes of each island are electrically isolated from electrodes of neighboring islands in at least one direction of the array. Source, drain and gate contact pads are provided to enable electrical testing of each island. After electrical testing of islands to identify defective islands, overlying electrical connections are formed to interconnect source electrodes in parallel, drain electrodes in parallel, and to interconnect gate electrodes to form a common gate electrode of large gate width Wg. Interconnections are provided selectively to good islands, while electrically isolating defective islands. This approach makes it economically feasible to fabricate large area GaN devices, including hybrid devices.
    Type: Grant
    Filed: October 28, 2014
    Date of Patent: November 14, 2017
    Assignee: GaN Systems Inc.
    Inventors: Greg P. Klowak, Cameron McKnight-Macneil, Howard Tweddle, Ahmad Mizan, Nigel Springett
  • Patent number: 9818692
    Abstract: Devices and systems comprising high current/high voltage GaN semiconductor devices are disclosed. A GaN die, comprising a lateral GaN transistor, is sandwiched between an overlying header and an underlying composite thermal dielectric layer. Fabrication comprises providing a conventional GaN device structure fabricated on a low cost silicon substrate (GaN-on-Si die), mechanically and electrically attaching source, drain and gate contact pads of the GaN-on-Si die to corresponding contact areas of conductive tracks of the header, then entirely removing the silicon substrate. The exposed substrate-surface of the epi-layer stack is coated with the composite dielectric thermal layer. Preferably, the header comprises a ceramic dielectric support layer having a CTE matched to the GaN epi-layer stack. The thermal dielectric layer comprises a high dielectric strength thermoplastic polymer and a dielectric filler having a high thermal conductivity.
    Type: Grant
    Filed: March 23, 2016
    Date of Patent: November 14, 2017
    Assignee: GaN Systems Inc.
    Inventors: John Roberts, Greg P. Klowak, Cameron McKnight-MacNeil
  • Publication number: 20170256638
    Abstract: A GaN-on-Si device structure and a method of fabrication are disclosed for improved die yield and device reliability of high current/high voltage lateral GaN transistors. A plurality of conventional GaN device structures comprising GaN epi-layers are fabricated on a silicon substrate (GaN-on-Si die). After processing of on-chip interconnect layers, a trench structure is defined around each die, through the GaN epi-layers and into the silicon substrate. A trench cladding is provided on proximal sidewalls, comprising at least one of a passivation layer and a conductive metal layer. The trench cladding extends over exposed surfaces of the GaN epi-layers, over the interface region with the substrate, and also over the exposed surfaces of the interconnect layers. This structure reduces risk of propagation of dicing damage and defects or cracks in the GaN epi-layers into active device regions. A metal trench cladding acts as a barrier for electro-migration of mobile ions.
    Type: Application
    Filed: March 2, 2017
    Publication date: September 7, 2017
    Inventors: Thomas MACELWEE, Greg P. KLOWAK, Howard TWEDDLE
  • Patent number: 9692408
    Abstract: An electronic switching system and device comprising driver circuits for power transistors are disclosed, with particular application for MOSFET driven, normally-on gallium nitride (GaN) power transistors. Preferably, a low power, high speed CMOS driver circuit with an integrated low voltage, lateral MOSFET driver is series coupled, in a hybrid cascode arrangement, to a high voltage GaN HEMT and provides for improved control of noise and voltage transients. Monitoring and control functions, including latching and clamping, are based on monitoring of Vcc conditions for shut-down and start-up conditioning to enable safer operation, particularly for high voltage and high current switching. Preferred embodiments also provide isolated, self-powered, high speed driver devices, with reduced input losses.
    Type: Grant
    Filed: December 12, 2013
    Date of Patent: June 27, 2017
    Assignee: GaN Systems Inc.
    Inventors: John Roberts, Greg P. Klowak
  • Patent number: 9659854
    Abstract: Embedded packaging for devices and systems comprising lateral GaN power transistors is disclosed. The packaging assembly is suitable for large area, high power GaN transistors and comprises an assembly of a GaN power transistor and package components comprising a three level interconnect structure. In preferred embodiments, the three level interconnect structure comprises an on-chip metal layer, a copper redistribution layer and package metal layers, in which there is a graduated or tapered contact area sizing through the three levels for dividing/applying current on-chip and combining/collecting current off-chip, with distributed contacts over the active area of the GaN power device. This embedded packaging assembly provides a low inductance, low resistance interconnect structure suitable for devices and systems comprising large area, high power GaN transistors for high voltage/high current applications.
    Type: Grant
    Filed: April 15, 2015
    Date of Patent: May 23, 2017
    Assignee: GaN Systems Inc.
    Inventors: Greg P. Klowak, Ahmad Mizan, John Roberts
  • Patent number: 9589869
    Abstract: Packaging solutions for devices and systems comprising lateral GaN power transistors are disclosed, including components of a packaging assembly, a semiconductor device structure, and a method of fabrication thereof. In the packaging assembly, a GaN die, comprising one or more lateral GaN power transistors, is sandwiched between first and second leadframe layers, and interconnected using low inductance interconnections, without wirebonding. For thermal dissipation, the dual leadframe package assembly can be configured for either front-side or back-side cooling. Preferred embodiments facilitate alignment and registration of high current/low inductance interconnects for lateral GaN devices, in which contact areas or pads for source, drain and gate contacts are provided on the front-side of the GaN die.
    Type: Grant
    Filed: March 9, 2016
    Date of Patent: March 7, 2017
    Assignee: GaN Systems Inc.
    Inventors: Cameron McKnight-MacNeil, Greg P. Klowak, Ahmad Mizan
  • Patent number: 9589868
    Abstract: Packaging solutions for large area, GaN die comprising one or more lateral GaN power transistor devices and systems are disclosed. Packaging assemblies comprise an interposer sub-assembly comprising the lateral GaN die and a leadframe. The GaN die is electrically connected to the leadframe using bump or post interconnections, silver sintering, or other low inductance interconnections. Then, attachment of the GaN die to the substrate and the electrical connections of the leadframe to contacts on the substrate are made in a single process step. The sub-assembly may be mounted in a standard power module, or alternatively on a substrate, such as a printed circuit board. For high current applications, the sub-assembly also comprises a ceramic substrate for heat dissipation. This packaging scheme provides interconnections with lower inductance and higher current capacity, simplifies fabrication, and enables improved thermal matching of components, compared with conventional wirebonded power modules.
    Type: Grant
    Filed: March 9, 2016
    Date of Patent: March 7, 2017
    Assignee: GaN Systems Inc.
    Inventors: Cameron McKnight-MacNeil, Greg P. Klowak, Ahmad Mizan
  • Publication number: 20160380090
    Abstract: Devices and systems comprising high current/high voltage GaN semiconductor devices are disclosed. A GaN die, comprising a lateral GaN transistor, is sandwiched between an overlying header and an underlying composite thermal dielectric layer. Fabrication comprises providing a conventional GaN device structure fabricated on a low cost silicon substrate (GaN-on-Si die), mechanically and electrically attaching source, drain and gate contact pads of the GaN-on-Si die to corresponding contact areas of conductive tracks of the header, then entirely removing the silicon substrate. The exposed substrate-surface of the epi-layer stack is coated with the composite dielectric thermal layer. Preferably, the header comprises a ceramic dielectric support layer having a CTE matched to the GaN epi-layer stack. The thermal dielectric layer comprises a high dielectric strength thermoplastic polymer and a dielectric filler having a high thermal conductivity.
    Type: Application
    Filed: March 23, 2016
    Publication date: December 29, 2016
    Inventors: John ROBERTS, Greg P. KLOWAK, Cameron MCKNIGHT-MACNEIL
  • Publication number: 20160307826
    Abstract: Packaging solutions for devices and systems comprising lateral GaN power transistors are disclosed, including components of a packaging assembly, a semiconductor device structure, and a method of fabrication thereof. In the packaging assembly, a GaN die, comprising one or more lateral GaN power transistors, is sandwiched between first and second leadframe layers, and interconnected using low inductance interconnections, without wirebonding. For thermal dissipation, the dual leadframe package assembly can be configured for either front-side or back-side cooling. Preferred embodiments facilitate alignment and registration of high current/low inductance interconnects for lateral GaN devices, in which contact areas or pads for source, drain and gate contacts are provided on the front-side of the GaN die.
    Type: Application
    Filed: June 30, 2016
    Publication date: October 20, 2016
    Inventors: Cameron MCKNIGHT-MACNEIL, Greg P. KLOWAK, Ahmad MIZAN, Stephen COATES
  • Publication number: 20160284829
    Abstract: A fault tolerant design for large area nitride semiconductor devices is provided, which facilitates testing and isolation of defective areas. A transistor comprises an array of a plurality of islands, each island comprising an active region, source and drain electrodes, and a gate electrode. Electrodes of each island are electrically isolated from electrodes of neighbouring islands in at least one direction of the array. Source, drain and gate contact pads are provided to enable electrical testing of each island. After electrical testing of islands to identify defective islands, overlying electrical connections are formed to interconnect source electrodes in parallel, drain electrodes in parallel, and to interconnect gate electrodes to form a common gate electrode of large gate width Wg. Interconnections are provided selectively to good islands, while electrically isolating defective islands. This approach makes it economically feasible to fabricate large area GaN devices, including hybrid devices.
    Type: Application
    Filed: October 28, 2014
    Publication date: September 29, 2016
    Inventors: Greg P. KLOWAK, Cameron MCKNIGHT-MACNEIL, Howard TWEDDLE, Ahmad MIZAN, Nigel SPRINGETT
  • Publication number: 20160268185
    Abstract: Packaging solutions for devices and systems comprising lateral GaN power transistors are disclosed, including components of a packaging assembly, a semiconductor device structure, and a method of fabrication thereof In the packaging assembly, a GaN die, comprising one or more lateral GaN power transistors, is sandwiched between first and second leadframe layers, and interconnected using low inductance interconnections, without wirebonding. For thermal dissipation, the dual leadframe package assembly can be configured for either front-side or back-side cooling. Preferred embodiments facilitate alignment and registration of high current/low inductance interconnects for lateral GaN devices, in which contact areas or pads for source, drain and gate contacts are provided on the front-side of the GaN die.
    Type: Application
    Filed: March 9, 2016
    Publication date: September 15, 2016
    Inventors: Cameron MCKNIGHT-MACNEIL, Greg P. KLOWAK, Ahmad MIZAN
  • Publication number: 20160268190
    Abstract: Packaging solutions for large area, GaN die comprising one or more lateral GaN power transistor devices and systems are disclosed. Packaging assemblies comprise an interposer sub-assembly comprising the lateral GaN die and a leadframe. The GaN die is electrically connected to the leadframe using bump or post interconnections, silver sintering, or other low inductance interconnections. Then, attachment of the GaN die to the substrate and the electrical connections of the leadframe to contacts on the substrate are made in a single process step. The sub-assembly may be mounted in a standard power module, or alternatively on a substrate, such as a printed circuit board. For high current applications, the sub-assembly also comprises a ceramic substrate for heat dissipation. This packaging scheme provides interconnections with lower inductance and higher current capacity, simplifies fabrication, and enables improved thermal matching of components, compared with conventional wirebonded power modules.
    Type: Application
    Filed: March 9, 2016
    Publication date: September 15, 2016
    Inventors: Cameron MCKNIGHT-MACNEIL, Greg P. KLOWAK, Ahmad MIZAN
  • Publication number: 20160240471
    Abstract: Embedded packaging for devices and systems comprising lateral GaN power transistors is disclosed. The packaging assembly is suitable for large area, high power GaN transistors and comprises an assembly of a GaN power transistor and package components comprising a three level interconnect structure. In preferred embodiments, the three level interconnect structure comprises an on-chip metal layer, a copper redistribution layer and package metal layers, in which there is a graduated or tapered contact area sizing through the three levels for dividing/applying current on-chip and combining/collecting current off-chip, with distributed contacts over the active area of the GaN power device. This embedded packaging assembly provides a low inductance, low resistance interconnect structure suitable for devices and systems comprising large area, high power GaN transistors for high voltage/high current applications.
    Type: Application
    Filed: April 15, 2015
    Publication date: August 18, 2016
    Inventors: Greg P. KLOWAK, Ahmad MIZAN, John ROBERTS
  • Publication number: 20150318851
    Abstract: An electronic switching system and device comprising driver circuits for power transistors are disclosed, with particular application for MOSFET driven, normally-on gallium nitride (GaN) power transistors. Preferably, a low power, high speed CMOS driver circuit with an integrated low voltage, lateral MOSFET driver is series coupled, in a hybrid cascode arrangement, to a high voltage GaN HEMT and provides for improved control of noise and voltage transients. Monitoring and control functions, including latching and clamping, are based on monitoring of Vcc conditions for shut-down and start-up conditioning to enable safer operation, particularly for high voltage and high current switching. Preferred embodiments also provide isolated, self-powered, high speed driver devices, with reduced input losses.
    Type: Application
    Filed: December 12, 2013
    Publication date: November 5, 2015
    Inventors: John ROBERTS, Greg P. KLOWAK