Curved Nitride Semiconductor Substrates for Off-Angle Morphology Control
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Solution Overview
Problem
Existing nitride semiconductor substrates face challenges in controlling the surface morphology due to unpredictable off-angle distributions, which affect the quality and performance of semiconductor layers.
Innovation Solution
A nitride semiconductor substrate with a (0001) plane curved in a concave spherical shape, where the off-angle is approximated using a specific formula, allowing for precise control of the surface morphology by adjusting the rate of change in the off-angle components along different axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat (0001) plane is used as the substrate surface, then the manufacturing process is simple, but the surface morphology of the semiconductor layer cannot be controlled
Solution Approach 1:
The (0001) plane of the nitride semiconductor substrate is curved in a concave spherical shape with respect to the main surface, rather than being flat. This curvature creates a controlled off-angle distribution across the substrate surface, enabling precise control of semiconductor layer surface morphology while maintaining manufacturing feasibility through a defined geometric relationship.
Solution Approach 2:
The invention changes the geometric parameter of the substrate surface from flat to curved, specifically defining the off-angle distribution through the curvature radius R and position coordinates (x, y). This parameter change allows systematic control of surface morphology by adjusting the curvature characteristics and off-angle distribution pattern.
2Adaptability or versatility
If the off-angle distribution is unpredictable, then various substrate orientations can occur, but the surface morphology of the semiconductor layer becomes difficult to control
Solution Approach 1:
The invention implements local quality by creating a specific off-angle distribution pattern across different regions of the substrate. The off-angle varies systematically with position coordinates (x, y) according to the concave spherical curvature, providing different local orientations that are precisely controlled rather than random, thereby enabling surface morphology control while maintaining orientation variety.
3Manufacturing precision
If a curved (0001) plane with controlled off-angle distribution is used, then surface morphology control is improved, but the substrate structure becomes more complex
Solution Approach 1:
The concave spherical curvature provides a mathematically defined and manufacturable geometric form that achieves controlled off-angle distribution. The curvature radius R and position-based off-angle relationship create a systematic structure that, while more complex than a flat surface, remains feasible to manufacture and provides precise control over surface morphology.
Data Source
AI summary
A nitride semiconductor substrate including a group III nitride semiconductor crystal and having a main surface, wherein a low index crystal plane is (0001) plane curved in a concave spherical shape to the main surface, and the off-angle (θm, θa) at a position (x, y) in the main surface approximated by x representing a coordinate in a direction along <1-100> axis, y is a coordinate in a direction along <11-20> axis, (0, 0) represents a coordinate (x, y) of the center, θm represents a direction component along <1-100> axis in an off-angle of <0001> axis with respect to a normal, θa represents a direction component along <11-20> axis in the off-angle, (M1, A1) represents a rate of change in the off-angle (θm, θa) with respect to the position (x, y) in the main surface, and (M2, A2) represents the off-angle (θm, θa) at the center.