Nitride Semiconductor Device with Integrated Freewheel Diode
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Solution Overview
Problem
Nitride semiconductor devices with freewheel diodes connected in antiparallel face challenges in achieving high breakdown voltage, low ON resistance, and low forward voltage, especially in normally off configurations, which are essential for downsizing switching power sources and inverter circuits.
Innovation Solution
The design incorporates a nitride semiconductor device with a specific structure including a substrate, InxGa1-x-yN layers, interlayer insulating films, and strategically positioned gate electrodes to form two-dimensional electron gases, allowing for a normally off FET with low ON resistance and high breakdown voltage, while the freewheel diode is integrated to manage circulating currents effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a normally off nitride semiconductor device is used, then the breakdown voltage is high and the device can be turned off reliably, but the ON resistance becomes high in the portion immediately below the gate electrode
Solution Approach 1:
The patent applies local quality by creating a recess structure only in the region immediately below the gate electrode, while leaving other regions intact. This localized modification reduces the ON resistance in the high-field region without compromising the overall breakdown voltage of the device. The recess allows for lower doping concentration or different material composition specifically where needed.
Solution Approach 2:
The patent introduces a vertical dimension by forming a recess structure that extends downward from the surface. This dimensional change allows the device to achieve low ON resistance through the recess region while maintaining high breakdown voltage through the undisturbed bulk structure above and around the recess.
2Volume of moving object
If the nitride semiconductor device is downsized for compact switching power sources and inverter circuits, then the device size is reduced, but it becomes more difficult to achieve both low forward voltage of the freewheel diode and low ON resistance
Solution Approach 1:
The patent merges the freewheel diode function with the FET structure by integrating the diode anode with the source region and the cathode with the drain region. This consolidation eliminates the need for separate discrete diode components, reducing overall device size while maintaining low forward voltage through optimized junction design.
Solution Approach 2:
The patent employs parameter changes by adjusting doping concentrations, layer thicknesses, and material compositions in the integrated FET-diode structure. These parameter optimizations enable the compact device to achieve low forward voltage for the freewheel diode and low ON resistance for the FET channel simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a nitride semiconductor device with high breakdown voltage, low ON resistance, and reduced forward voltage for the freewheel diode, enhancing the performance of switching power sources and inverter circuits by effectively managing current flow and reducing power loss.
Implementation Method 1
configured to form a two-dimensional electron gas at an interface with the first Inx1Ga1-x1-y1Aly1N layer
Data Source
AI summary
A nitride semiconductor device includes a substrate, a first Inx1Ga1-x1-y1Aly1N layer, a second Inx2Ga1-x2-y2Aly2N layer, an interlayer insulating film, a source electrode, a drain electrode, a first gate electrode, a Schottky electrode, a second gate electrode, an interconnection layer. The second Inx2Ga1-x2-y2Aly2N layer is provided on a surface of the first Inx1Ga1-x1-y1Aly1N layer. The second Inx2Ga1-x2-y2Aly2N layer has a wider band gap than the first Inx1Ga1-x1-y1Aly1N layer. The first gate electrode is provided between the source electrode and the drain electrode on a surface of the second Inx2Ga1-x2-y2Aly2N layer. The Schottky electrode is provided on the second Inx2Ga1-x2-y2Aly2N layer between the first gate electrode and the drain electrode. The second gate electrode is provided on the second Inx2Ga1-x2-y2Aly2N layer between the Schottky electrode and the drain electrode. The interconnection layer electrically connects the source electrode, the Schottky electrode, and the second gate electrode.