Nitride Semiconductor Substrate Slicing Cleavage Reduction
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Solution Overview
Problem
The existing methods for manufacturing nitride semiconductor substrates, particularly GaN substrates, face significant challenges with cleavage during slicing, leading to a low yield rate, especially for larger diameter and thicker crystals, due to strain and impurity concentration differences between the outer peripheral and central parts of the crystal.
Innovation Solution
A method involving vapor phase epitaxy to grow nitride semiconductor single crystals, followed by grinding the outer peripheral surface with a minimum amount of 1.5 mm to reduce cleavage and improve yield, using a grinding process that sets the surface roughness to 3 μm or less to enhance slicing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the GaN single crystal is sliced without outer peripheral grinding, then the manufacturing process is simpler and faster, but cleavage is generated during slicing resulting in poor yield rate
Solution Approach 1:
The patent applies preliminary outer peripheral grinding to the GaN single crystal before slicing to remove the strained outer peripheral portion. This preliminary action eliminates the cause of cleavage generation, ensuring high yield rate during subsequent slicing operations while maintaining a manageable process complexity through a single additional grinding step.
2Productivity
If the outer peripheral surface is ground with a small grinding amount, then the manufacturing process is faster and less complex, but cleavage is easily generated during slicing
Solution Approach 1:
The patent specifies a critical parameter threshold of 1.5 mm or more for the outer peripheral grinding amount. By changing the grinding amount parameter to meet or exceed this threshold, the patent eliminates cleavage generation during slicing, achieving high yield rate while controlling grinding time through a clearly defined parameter range.
3Manufacturing precision
If the GaN single crystal has a large diameter and is thick, then the substrate quality is better, but cleavage is easily generated during slicing
Solution Approach 1:
The patent extracts and removes the problematic outer peripheral portion of the GaN single crystal through grinding. This extracted portion contains the strain and impurity concentration differences that cause cleavage, allowing the remaining central portion to be sliced without cleavage generation, thereby maintaining high substrate quality for large diameter and thick crystals.
4Productivity
If outer peripheral grinding is performed to reduce cleavage, then the yield rate improves, but the manufacturing cost increases
Solution Approach 1:
The patent optimizes the grinding amount parameter to a specific threshold of 1.5 mm or more, which is sufficient to eliminate cleavage generation. By setting this precise parameter, the patent achieves high yield rate improvement while controlling manufacturing cost through minimal necessary grinding, avoiding excessive material removal and associated costs.
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 approach significantly reduces cleavage during slicing and dramatically improves the yield rate of nitride semiconductor substrates, making the manufacturing process more cost-effective by minimizing manufacturing costs associated with high yield improvements.
Implementation Method 1
growing a nitride semiconductor single crystal on a seed crystal substrate by vapor phase epitaxy
Implementation Method 2
grinding an outer peripheral surface of the grown nitride semiconductor single crystal
Data Source
AI summary
The invention provides a method for manufacturing a nitride semiconductor substrate capable of reducing a cleavage during slicing of the nitride semiconductor single crystal and capable of improving a yield rate of the nitride semiconductor substrate. The method includes growing a nitride semiconductor single crystal on a seed crystal substrate by vapor phase epitaxy; grinding an outer peripheral surface the grown nitride semiconductor single crystal; and slicing the nitride semiconductor single crystal with its outer peripheral surface ground. A grinding amount of the outer peripheral surface of the nitride semiconductor single crystal in the step of grinding is 1.5 mm or more.