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Anant K. Agarwal, Chapel Hill US

Anant K. Agarwal, Chapel Hill, NC US

Patent application numberDescriptionPublished
20090004883Methods of fabricating oxide layers on silicon carbide layers utilizing atomic oxygen - Methods of forming oxide layers on silicon carbide layers are disclosed, including placing a silicon carbide layer in a chamber such as an oxidation furnace tube that is substantially free of metallic impurities, heating an atmosphere of the chamber to a temperature of about 500° C. to about 1300° C., introducing atomic oxygen in the chamber, and flowing the atomic oxygen over a surface of the silicon carbide layer to thereby form an oxide layer on the silicon carbide layer. In some embodiments, introducing atomic includes oxygen providing a source oxide in the chamber and flowing a mixture of nitrogen and oxygen gas over the source oxide. The source oxide may comprise aluminum oxide or another oxide such as manganese oxide. Some methods include forming an oxide layer on a silicon carbide layer and annealing the oxide layer in an atmosphere including atomic oxygen.01-01-2009
20090035926Methods of Fabricating Silicon Carbide Devices Incorporating Multiple Floating Guard Ring Edge Terminations - Edge termination for silicon carbide devices has a plurality of concentric floating guard rings in a silicon carbide layer that are adjacent and spaced apart from a silicon carbide-based semiconductor junction. An insulating layer, such as an oxide, is provided on the floating guard rings and a silicon carbide surface charge compensation region is provided between the floating guard rings and is adjacent the insulating layer. Methods of fabricating such edge termination are also provided.02-05-2009
20090121319POWER SEMICONDUCTOR DEVICES WITH MESA STRUCTURES AND BUFFER LAYERS INCLUDING MESA STEPS - A bipolar junction transistor includes a collector having a first conductivity type, a drift layer having the first conductivity type on the collector, a base layer on the drift layer and having a second conductivity type opposite the first conductivity type, a lightly doped buffer layer having the first conductivity type on the base layer and forming a p-n junction with the base layer, and an emitter mesa having the first conductivity type on the buffer layer and having a sidewall. The buffer layer includes a mesa step adjacent to and spaced laterally apart from the sidewall of the emitter mesa, and a first thickness of the buffer layer beneath the emitter mesa is greater than a second thickness of the buffer layer outside the mesa step.05-14-2009
20090212301Double Guard Ring Edge Termination for Silicon Carbide Devices and Methods of Fabricating Silicon Carbide Devices Incorporating Same - 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.08-27-2009
20100009545Methods of Fabricating Oxide Layers on Silicon Carbide Layers Utilizing Atomic Oxygen - Methods of forming oxide layers on silicon carbide layers are disclosed, including placing a silicon carbide layer in a chamber such as an oxidation furnace tube that is substantially free of metallic impurities, heating an atmosphere of the chamber to a temperature of about 500° C. to about 1300° C., introducing atomic oxygen in the chamber, and flowing the atomic oxygen over a surface of the silicon carbide layer to thereby form an oxide layer on the silicon carbide layer. In some embodiments, introducing atomic includes oxygen providing a source oxide in the chamber and flowing a mixture of nitrogen and oxygen gas over the source oxide. The source oxide may comprise aluminum oxide or another oxide such as manganese oxide. Some methods include forming an oxide layer on a silicon carbide layer and annealing the oxide layer in an atmosphere including atomic oxygen.01-14-2010
20100032685MESA TERMINATION STRUCTURES FOR POWER SEMICONDUCTOR DEVICES AND METHODS OF FORMING POWER SEMICONDUCTOR DEVICES WITH MESA TERMINATION STRUCTURES - An electronic device includes a drift layer having a first conductivity type, a buffer layer having a second conductivity type, opposite the first conductivity type, on the drift layer and forming a P—N junction with the drift layer, and a junction termination extension region having the second conductivity type in the drift layer adjacent the P—N junction. The buffer layer includes a step portion that extends over a buried portion of the junction termination extension. Related methods are also disclosed.02-11-2010
20100133549Semiconductor Devices with Current Shifting Regions and Related Methods - A semiconductor device may include a semiconductor buffer layer having a first conductivity type and a semiconductor mesa having the first conductivity type on a surface of the buffer layer. In addition, a current shifting region having a second conductivity type may be provided adjacent a corner between the semiconductor mesa and the semiconductor buffer layer, and the first and second conductivity types may be different conductivity types. Related methods are also discussed.06-03-2010
20100289032DIFFUSED JUNCTION TERMINATION STRUCTURES FOR SILICON CARBIDE DEVICES AND METHODS OF FABRICATING SILICON CARBIDE DEVICES INCORPORATING SAME - 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 2×1011-18-2010
20100301929Power Switching Devices Having Controllable Surge Current Capabilities - Semiconductor switching devices include a wide band-gap power transistor, a wide band-gap surge current transistor that coupled in parallel to the power transistor, and a wide hand-gap driver transistor that is configured to drive the surge current transistor. Substantially all of the on-state output current of the semiconductor switching device flows through the channel of the power transistor when a drain-source voltage of the power transistor is within a first voltage range, which range may correspond, for example, to the drain-source voltages expected during normal operation. In contrast, the semiconductor switching device is further configured so that in the on-state the output current flows through both the surge current transistor and the channel of the power transistor when the drain-source voltage of the power transistor is within a second, higher voltage range.12-02-2010
20110012129High-Gain Wide Bandgap Darlington Transistors and Related Methods of Fabrication - 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.01-20-2011
20110081772METHODS OF FABRICATING SILICON CARBIDE DEVICES INCORPORATING MULTIPLE FLOATING GUARD RING EDGE TERMINATIONS - Edge termination for silicon carbide devices has a plurality of concentric floating guard rings in a silicon carbide layer that are adjacent and spaced apart from a silicon carbide-based semiconductor junction. An insulating layer, such as an oxide, is provided on the floating guard rings and a silicon carbide surface charge compensation region is provided between the floating guard rings and is adjacent the insulating layer. Methods of fabricating such edge termination are also provided.04-07-2011
20110084284Transistors with Semiconductor Interconnection Layers and Semiconductor Channel Layers of Different Semiconductor Materials - A transistor may include a semiconductor drift layer of a first semiconductor material and a semiconductor channel layer on the semiconductor drift layer. The semiconductor channel layer may include a second semiconductor material different than the first semiconductor material. A semiconductor interconnection layer may be electrically coupled between the semiconductor drift layer and the semiconductor channel layer, and the semiconductor interconnection layer may include a third semiconductor material different than the first and second semiconductor materials. In addition, a control electrode may be provided on the semiconductor channel layer.04-14-2011

Patent applications by Anant K. Agarwal, Chapel Hill, NC US