Nitride Semiconductor Substrate Warping Pattern for Low Off-Angle Variation
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Solution Overview
Problem
Group-III element nitride semiconductor substrates often exhibit significant off-angle variations due to warping, leading to roughened surface morphology and functional fluctuations in devices such as LEDs, particularly in large-diameter substrates, which complicates flattening processing and increases the risk of substrate breakage.
Innovation Solution
A Group-III element nitride semiconductor substrate with a controlled warping pattern featuring multiple extremes and specific intervals, resulting in an off-angle variation of 0.40° or less, is achieved by forming a freestanding substrate with a plurality of extremes in the crystal plane warping, allowing for reduced off-angle variation and improved substrate stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If flattening processing is applied to warped substrates, then substrate flatness is improved, but off-angle variation increases
Solution Approach 1:
The patent applies preliminary flattening processing before the Group-III element nitride layer is completely peeled from the base substrate. This preliminary action reduces warping while the layer is still supported by the base substrate, preventing excessive off-angle variation from developing before flattening occurs
2Productivity
If large-diameter substrates are used, then device productivity is improved, but off-angle variation increases
Solution Approach 1:
The patent performs flattening processing at an intermediate stage when the Group-III element nitride layer is still partially attached to the base substrate. This timing allows large-diameter substrates to be flattened effectively before warping becomes excessive, enabling high-productivity large-diameter substrate production while maintaining acceptable off-angle variation
3Stability of the object's composition
If complete peeling is performed, then substrate independence is improved, but warping increases
Solution Approach 1:
The patent performs flattening processing before complete peeling occurs. This preliminary action reduces warping while the layer still has mechanical support from the base substrate, achieving a balance between substrate independence and shape control
4Manufacturing precision
If off-angle variation is reduced, then surface morphology is improved, but processing complexity increases
Solution Approach 1:
The patent performs flattening processing at an optimal intermediate stage during the peeling process. This timing allows warping to be controlled effectively with a single flattening step, rather than requiring multiple processing steps that would increase overall process complexity
Data Source
AI summary
A Group-III element nitride semiconductor substrate includes: a first surface; and a second surface, wherein warping of a crystal plane of the first surface has a plurality of extremes.