Nitride Vertical Transistor Gate Structure for Low Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional nitride semiconductor vertical transistors suffer from high leakage current and low breakdown voltage when in the off state due to electrical field concentration at the barrier layer, which is exacerbated by impurities at the regrown interface of the pn junction.
Innovation Solution
A nitride semiconductor device is designed with a substrate, n-type and p-type nitride semiconductor layers, electron transport and supply layers, and a gate electrode configuration where the bottom face of the gate electrode is closer to the drain electrode than the p-type nitride semiconductor layer, alleviating electrical field concentration and incorporating a high-resistance layer to suppress channel narrowing and breakdown voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional vertical transistor structure is used, then the device can be manufactured with standard processes, but leakage current is high when the transistor is in an off state
Solution Approach 1:
The transistor structure is segmented into distinct functional regions: a first region with a first doping concentration and a second region with a second doping concentration. This segmentation allows independent optimization of each region's properties to reduce leakage current while maintaining device functionality.
Solution Approach 2:
Different regions of the transistor are assigned different doping concentrations tailored to their specific functions. The first region has a first doping concentration optimized for its role, while the second region has a second doping concentration optimized for its role, allowing local optimization of electrical characteristics to reduce leakage.
2Reliability
If a conventional vertical transistor structure is used, then manufacturing is straightforward, but breakdown voltage is low
Solution Approach 1:
The transistor is divided into multiple regions with different doping concentrations that work together to enhance breakdown voltage. The segmented structure allows each region to contribute to the overall breakdown characteristic through its specific doping level.
Solution Approach 2:
The doping concentration parameter is changed between different regions of the transistor. By varying the doping concentration from the first region to the second region, the electrical characteristics are modified to increase the breakdown voltage while maintaining manufacturability.
3Reliability
If the gate electrode bottom face is positioned closer to the drain electrode, then breakdown voltage increases, but manufacturing precision requirements increase
Solution Approach 1:
The gate electrode positioning is designed in advance with a predetermined distance from the drain electrode to ensure proper electrical characteristics. This preliminary design allows the breakdown voltage to be optimized while accounting for manufacturing tolerances.
Solution Approach 2:
The distance parameter between the gate electrode bottom face and drain electrode is optimized to balance breakdown voltage enhancement with manufacturability. By carefully selecting this parameter, the design achieves high breakdown voltage without requiring excessive manufacturing precision.
Data Source
AI summary
A nitride semiconductor device includes: a substrate; an n-type drift layer; a p-type blocking layer; a gate opening which penetrates through the blocking layer to the drift layer; an electron transport layer and an electron supply layer provided on an inner face of the gate opening; a gate electrode above the electron supply layer and covering the gate opening; a source opening penetrating through the electron supply layer and the electron transport layer to the blocking layer; a source electrode covering the source opening, the source electrode being connected to the electron supply layer, the electron transport layer, and the blocking layer; and a drain electrode on a side of the substrate opposite from a side on which the blocking layer is located. A bottom face of the gate electrode is closer to the drain electrode than a bottom face of the blocking layer is.