Nitride Semiconductor Gate Opening Shape for Low Leakage
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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
1Reliability
If a conventional hexagonal opening shape is used in the nitride semiconductor device, then the manufacturing process is simple, but leakage current is generated between the gate and source at the end of the opening and breakdown voltage is reduced
Solution Approach 1:
The patent applies curvature by changing the opening shape from a conventional hexagonal form to one where at least part of the outline of the end follows an arc or elliptical arc. This curved geometry eliminates the sharp corners that act as singular growth points, thereby preventing abnormal growth in the regrown layer and reducing leakage current while maintaining high breakdown voltage.
Solution Approach 2:
The patent applies local quality by making the opening shape non-uniform - specifically, only part of the outline at the end of the opening follows an arc or elliptical arc, while other portions may remain straight. This localized application of curvature targets the specific region where abnormal growth occurs (at the ends of the opening) without unnecessarily complicating the entire structure.
2Manufacturing precision
If the opening ends have sharp corners (hexagonal shape), then the structure is well-defined and easy to manufacture, but abnormal growth occurs creating voids and reducing film quality
Solution Approach 1:
The patent replaces sharp corners with curved surfaces (arc or elliptical arc) at the ends of the opening. This eliminates singular growth points that cause abnormal growth and void formation, thereby improving film quality of the regrown layer while still maintaining a well-defined geometric shape that can be manufactured.
Solution Approach 2:
The patent introduces asymmetry in the opening shape by having at least part of the outline follow an arc or elliptical arc, which is inherently asymmetric compared to the symmetric hexagonal shape. This asymmetric curvature prevents the uniform radial growth that occurs at sharp corners, eliminating abnormal growth patterns.
Data Source
AI summary
A nitride semiconductor device includes a substrate, a drift layer and a block layer sequentially provided above the substrate, a gate opening penetrating through a block layer and reaching a drift layer, an electron transit layer and an electron supply layer sequentially provided above the block layer and along the inner surface of the gate opening, a gate electrode provided to cover the gate opening, a source opening penetrating through an electron supply layer and an electron transit layer and reaching the block layer, a source electrode provided in the source opening, and a drain electrode on the rear surface side of the substrate. Seen in a plan view, at least part of an outline of an end of the gate opening in the longitudinal direction follows an arc or an elliptical arc.