Group III Nitride Substrate Crystallinity Gradient Against Warping
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Solution Overview
Problem
Group-III element nitride substrates produced by heteroepitaxial growth are prone to warping, which affects their structural integrity and performance.
Innovation Solution
A Group-III element nitride substrate with a controlled crystallinity gradient is produced by varying the growth conditions and separating the nitride crystal from a base substrate, ensuring higher crystallinity in the central portion and lower crystallinity in the peripheral edge portion, with a low-angle grain boundary to alleviate stress and suppress warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heteroepitaxial growth is used to produce Group-III element nitride substrates, then substrate production is achieved, but warping occurs affecting structural integrity
Solution Approach 1:
The patent applies local quality by creating a radial gradient in crystallinity across the substrate, with the central portion having higher crystallinity and the peripheral portion having lower crystallinity. This non-uniform crystallinity distribution is intentionally designed to balance internal stresses and suppress warping while maintaining overall substrate quality for device fabrication.
2Productivity
If large-sized substrates are produced, then device production efficiency is improved, but warping increases affecting structural stability
Solution Approach 1:
The patent employs parameter changes by systematically varying the crystallinity parameter across the substrate radius. The central portion maintains high crystallinity for optimal device performance, while the peripheral portion has reduced crystallinity to minimize stress accumulation. This parameter gradient approach enables the production of large-sized substrates with improved structural stability and reduced warping.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively suppresses warping in large-sized substrates, enhancing their structural stability and enabling uniform deposition of functional layers, improving device production efficiency.
Implementation Method 1
The Group-III element nitride substrate may be obtained by, for example, as described in Patent Literature 1, adopting a substrate formed of a material different in composition such as a sapphire substrate as a base substrate, and heteroepitaxially growing a Group-III element nitride crystal on the base substrate.
Implementation Method 2
a half-width W2 of a diffraction peak of a (10-12) plane obtained by X-ray diffraction rocking curve measurement in the second part may be larger than a half-width W1 of a diffraction peak of the (10-12) plane obtained by the X-ray diffraction rocking curve measurement in the first part.
Data Source
AI summary
A Group-III element nitride substrate includes a first main surface and a second main surface facing each other, wherein, in the first main surface, crystallinity of a first part positioned on a central portion thereof is higher than crystallinity of a second part positioned outside the first part.