Vertical GaN Diode Trench Structure for On-Resistance Reduction
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Solution Overview
Problem
Conventional GaN-based diodes have high on-resistance, large device area, and poor thermal performance due to lateral current flow and single-sided thermal dissipation.
Innovation Solution
The diode design is modified to include trenches etched through active layers and substrate, lined with conductive material, allowing both lateral and vertical current flow from the anode to a cathode located on the backside of the substrate, reducing total resistance and enhancing thermal dissipation by enabling current to flow through a low-resistivity substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional lateral GaN-based diode structure is used, then the device can be manufactured with standard processes, but the on-resistance is relatively large due to current having to channel through the AlGaN barrier layer
Solution Approach 1:
The patent transitions from a lateral current flow configuration to a vertical current flow configuration by etching trenches through the AlGaN barrier layer and filling them with conductive material. This dimensional change allows current to flow vertically through the substrate rather than laterally through the high-resistance barrier layer, significantly reducing on-resistance while maintaining compatibility with standard manufacturing processes
2Device complexity
If the anode and cathode are located on the same face of the device, then the device structure is simplified, but the die area required is relatively large
Solution Approach 1:
The patent inverts the conventional lateral diode structure by positioning the cathode on the backside of the substrate rather than on the same face as the anode. This inversion enables vertical current flow through the substrate and reduces the required die area, as the current path is shortened and thermal dissipation is improved through the substrate
3Device complexity
If thermal dissipation is limited to only one side of the die, then the device structure is simpler, but the thermal performance is relatively poor
Solution Approach 1:
The patent utilizes the vertical dimension by etching trenches through the barrier layer and filling them with conductive material that extends to the substrate. This enables thermal dissipation through the substrate in addition to the top surface, effectively creating a three-dimensional thermal management pathway that improves thermal performance without significantly increasing device complexity
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
This configuration significantly reduces on-resistance and device area while improving thermal performance by allowing current to flow vertically through the substrate, resulting in lower switching losses and enhanced thermal management.
Implementation Method 1
A quantum well is formed at the hetero junction interface between the AlGaN layer, which has a large band gap, and the GaN layer, which has a narrower band gap. As a result, electrons are trapped in the quantum well.
Implementation Method 2
the hetero-structure formed from aluminum gallium nitride (AlGaN) and gallium nitride gives rise to a two-dimensional channel of high-mobility electrons
Implementation Method 3
A first metal layer forms a Schottky contact 140 to the aluminum gallium nitride barrier layer 135
Data Source
AI summary
A semiconductor device includes a substrate having first and second sides and a first active layer disposed over the first side of the substrate. A second active layer is disposed on the first active layer. The second active layer has a higher bandgap than the first active layer such that a two-dimensional electron gas layer arises between the first active layer and the second active layer. At least one trench extends through the first and second active layers and the two-dimensional electron gas layer and into the substrate. A conductive material lines the trench. A first electrode is disposed on the second active layer and a second electrode is disposed on the second side of the substrate.