Nitride Semiconductor Opening Geometry for Low Leakage Regrowth
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Solution Overview
Problem
Conventional nitride semiconductor devices experience leakage current and reduced breakdown voltage due to abnormal growth at the ends of openings, primarily attributed to the hexagonal shape of the opening ends which create singular growth points and voids in the regrown layer.
Innovation Solution
The nitride semiconductor device incorporates a substrate with a first nitride semiconductor layer, a block layer, an electron transit layer, and an electron supply layer, where the first opening and source electrode are elongated and follow an arc or elliptical arc shape, suppressing drastic changes in growth direction and abnormal growth, thereby improving film quality and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional hexagonal opening shape is used in the nitride semiconductor device, then the manufacturing process is simple, but leakage current is generated at the end of the opening and breakdown voltage is reduced
Solution Approach 1:
The opening end shape is changed from a conventional hexagonal shape with sharp corners to a rounded shape with a curvature radius of 0.5 μm or more. This curvature eliminates the singular growth points at the corners, preventing abnormal growth and void formation in the regrown layer, thereby suppressing leakage current and improving breakdown voltage while maintaining manufacturing feasibility through controlled rounding processes
2Manufacturing precision
If the opening end has sharp corners (hexagonal shape), then the opening can be easily defined, but abnormal growth occurs at the ends creating singular growth points and voids
Solution Approach 1:
The opening end is designed with a curved shape having a curvature radius of 0.5 μm or more, which eliminates the sharp corners that serve as singular growth points. This curvature prevents abnormal growth patterns and void formation in the regrown layer, ensuring stable and uniform regrowth while the opening definition is maintained through controlled curvature in the epitaxial growth process
3Device complexity
If conventional opening design is used, then the device structure is simple, but leakage current is generated reducing device performance
Solution Approach 1:
The opening end is designed with a curved shape having a curvature radius of 0.5 μm or more, which eliminates the sharp corners that serve as singular growth points. This curvature prevents abnormal growth patterns and void formation in the regrown layer, ensuring stable and uniform regrowth while the opening definition is maintained through controlled curvature in the epitaxial growth process
Data Source
AI summary
A nitride semiconductor device, including a substrate with a first nitride semiconductor layer on its surface, a block layer, an electron transit layer and an electron supply layer sequentially formed thereon. Formed along an inner surface thereof a first opening penetrating through the block layer to the first nitride semiconductor layer, a source electrode provided in a second opening in a location away from the first opening and connected to the block layer. The second opening penetrating through the electron supply and electron transit layers to the block layer. On an opposite surface of the substrate a drain electrode is provided. Seen in plan view, the first opening and the source electrode extend in a same, longitudinal direction, and the first opening includes: two straight portions extending in the longitudinal direction with the source electrode being interposed therebetween, and a first connection portion connecting ends of the two straight portions.