Gallium Nitride Substrate Grinding Direction Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The polarity of gallium nitride single crystals affects their workability during machining, particularly when grinding semipolar and nonpolar planes, leading to reduced light emission efficiency due to the droop phenomenon and anisotropy in machining characteristics.
Innovation Solution
A method of manufacturing gallium nitride single-crystal substrates involves grinding the main surface by arranging a single-crystal holder with a gallium nitride single crystal and a grindstone holder with a grindstone to face each other, and pressing them against each other while rotating one or both, with the grindstone direction controlled within specific angular ranges to optimize surface roughness and workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gallium nitride single crystal with semipolar plane or nonpolar plane is used to avoid droop phenomenon, then light emission efficiency is improved, but machining workability deteriorates due to polarity-induced anisotropy
Solution Approach 1:
The patent changes the machining parameters (grinding direction angle relative to crystal orientation, rotational speed, feed rate) to optimize workability for semipolar and nonpolar planes. Specifically, it defines precise angular ranges for the grinding direction relative to the projected c-axis direction, and adjusts rotational speeds of the crystal holder and grindstone holder to achieve uniform surface roughness and reduce residual stress.
2Device complexity
If conventional grinding method is used without considering crystal orientation, then manufacturing process is simple, but surface roughness and residual stress become uncontrolled
Solution Approach 1:
The patent establishes preliminary guidelines for grinding semipolar and nonpolar planes by defining the relationship between grinding direction and crystal orientation before the actual machining process. It specifies that the grinding direction should be within certain angular ranges relative to the projected c-axis direction, and pre-determines appropriate rotational speed ratios between the crystal holder and grindstone holder based on the specific plane orientation.
3Adaptability or versatility
If grinding direction is not aligned with crystal orientation, then machining flexibility is high, but anisotropy in workability increases and surface quality deteriorates
Solution Approach 1:
The patent applies different grinding parameters for different regions of the crystal based on their orientation. It divides the grinding process into specific angular zones relative to the projected c-axis direction and assigns optimized parameters to each zone, allowing the grinding direction to be adapted locally to the crystal orientation at each position.
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
This method improves the workability and surface roughness of gallium nitride single-crystal substrates with semipolar and nonpolar planes, reducing residual stress and enhancing the light emission efficiency by properly aligning the grindstone direction relative to the crystal orientation.
Implementation Method 1
a step of grinding a main surface by arranging a single-crystal holder holding a gallium nitride single crystal and a grindstone holder holding a grindstone to face each other, and pressing the gallium nitride single crystal and the grindstone against each other while rotating one or both
Data Source
AI summary
A method of manufacturing a gallium nitride single-crystal substrate includes a step of grinding a main surface by arranging a grindstone and a gallium nitride single crystal having a semipolar plane or a nonpolar plane as the main surface to face each other and pressing the grindstone and the gallium nitride single crystal against each other while moving the grindstone and the gallium nitride single crystal relative to each other. The main surface is ground to make an angle formed by a direction in which the grindstone grinds the main surface and a direction obtained by projecting a c-axis of the gallium nitride single crystal onto the main surface within at least one range selected from (A)-45° or more and 45° or less; (B) 55° or more and 135° or less; and (C) −135° or more and −55° or less.