GaAs Wafer Orientation Flat Cleaving for Off-Angle Accuracy
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Solution Overview
Problem
GaAs wafers with off angles face challenges in achieving high accuracy for orientation flat formation, leading to variations in orientation accuracy among wafers cut from the same ingot, particularly for large-diameter wafers used in LD devices, resulting in poor product yield.
Innovation Solution
A method involving grinding to form a provisional orientation flat, slicing to create a material wafer with an off angle, and cleaving to form the orientation flat at a specific interval (9 mm or more) based on the provisional flat, ensuring accurate orientation and stability across multiple wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional method (including PTL 1) is used to form an orientation flat on a GaAs wafer with an off angle, then the production process can be completed, but the orientation accuracy of the orientation flat varies between wafers and cannot be ensured with high accuracy
Solution Approach 1:
The invention applies preliminary action by forming a provisional orientation flat on the GaAs ingot before slicing into wafers. This provisional flat serves as a reference for determining the orientation of the final orientation flat on each wafer, ensuring consistent and accurate orientation across all wafers cut from the same ingot, thereby resolving the variability issue in conventional methods
Solution Approach 2:
The invention changes the parameter of the cleavage position by specifying that the orientation flat must be formed at a position where the distance from the wafer surface along the radial direction is 9 mm or more. This parameter change ensures that the cleavage occurs at an optimal location that maintains high orientation accuracy while accommodating the off-angle geometry of GaAs wafers
2Length of moving object
If the diameter of GaAs wafers is increased for LD device production, then the device performance is improved, but the orientation accuracy of the orientation flat deteriorates when the wafer has an off angle
Solution Approach 1:
The invention addresses the challenge of large-diameter wafers by changing the parameter of the cleavage position specification. By requiring the orientation flat to be formed at a position where the radial distance from the surface is 9 mm or more, the method ensures accurate orientation even across the larger wafer diameter, preventing the deterioration of orientation accuracy that would otherwise occur with increased wafer size
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 achieves high accuracy and stability in orientation flat formation for GaAs wafers with off angles, reducing variations and improving the product yield by maintaining mean orientation accuracy within ±0.010° and standard deviation of 0.009° or less across the wafer group.
Implementation Method 1
a grinding step of grinding a peripheral surface of a GaAs ingot including formation of a provisional orientation flat
Implementation Method 2
a slicing step of slicing the GaAs ingot after the grinding step to cut out a material wafer having an off angle
Implementation Method 3
a cleaving step of applying marking to the material wafer according to an orientation of an orientation flat determined based on the provisional orientation flat and cleaving the material wafer toward a peripheral surface of the material wafer from the marking to form the orientation flat
Data Source
AI summary
A method of producing a GaAs wafer having excellent OF orientation stability even in a GaAs wafer having an off angle, and a GaAs wafer group are provided. A method of producing a GaAs wafer includes: a grinding step of grinding a peripheral surface of a GaAs ingot including formation of a provisional orientation flat; a slicing step of slicing the GaAs ingot after the grinding step to cut out a material wafer having an off angle; and a cleaving step of applying marking to the material wafer according to an orientation of an orientation flat determined based on the provisional orientation flat and cleaving the material wafer toward a peripheral surface of the material wafer from the marking to form the orientation flat.