Alternating Group 13 Nitride Layers for Reduced Substrate Warping
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Solution Overview
Problem
Existing gallium nitride free-standing substrates exhibit significant warping, typically ranging from 100 to 200 μm in φ of 50 mm, which needs to be reduced to 30 μm or lower for improved structural integrity and functionality.
Innovation Solution
A group 13 nitride crystal layer is designed with alternating high-luminance and low-luminance layers, where the low-luminance layers have thicknesses between 3 and 10, and the high-luminance layers have thicknesses of 1, forming a super-lattice structure to minimize warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional gallium nitride crystal layer is grown by flux method, then large size crystals can be produced, but significant warping occurs (100 to 200 μm in φ of 50 mm)
Solution Approach 1:
The crystal layer is segmented into alternating high-luminance and low-luminance layers with specific thickness ratios. This segmentation creates a composite structure where the low-luminance layers (3-10 times thicker than high-luminance layers) act as stress compensation zones, reducing overall warping while maintaining large crystal size for device fabrication
Solution Approach 2:
The invention creates a composite crystal structure by alternating high-luminance and low-luminance layers with different optical and mechanical properties. The low-luminance layers, being significantly thicker, provide structural stability and warping reduction, while the high-luminance layers contribute to optical performance, achieving both large size and low warping
2Stability of the object's composition
If the crystal layer structure is modified to reduce warping, then structural stability improves, but manufacturing complexity increases
Solution Approach 1:
The invention controls warping by changing the thickness parameter of alternating layers, specifically making low-luminance layers 3-10 times thicker than high-luminance layers. This parameter adjustment creates a super-lattice structure that reduces warping to 30 μm or lower while maintaining manufacturability through flux method growth
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 alternating layer structure effectively reduces warping to acceptable levels, enhancing the structural stability and usability of the gallium nitride substrates for semiconductor and light-emitting devices.
Implementation Method 1
the microstructure in which the thinner high-luminance layers rich in dopants and impurity metals and the thicker low-luminance layers containing less dopants and impurity metals are alternately laminated. It was found that such microstructure functions as a kind of super-lattice structure to reduce the physical warping of the group 13 nitride crystal layer
Implementation Method 2
when a cross section of the group 13 nitride crystal layer cut in a direction perpendicular to the upper surface is observed by cathode luminescence
Data Source
AI summary
A group 13 nitride crystal layer is composed of a group 13 nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof, and the group 13 nitride crystal layer includes an upper surface and bottom surface. The group 13 nitride crystal layer includes high-luminance layers and low-luminance layers being present alternately, and the low-luminance layers have thicknesses of 3 or larger and 10 or smaller provided that 1 is assigned to a thickness of the high-luminance layer, when a cross section of the group 13 nitride crystal layer cut in a direction perpendicular to the upper surface is observed by cathode luminescence.