GaN Wafer Separation Layering for Low-Loss Ingot Slicing
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Solution Overview
Problem
The existing method of manufacturing gallium nitride (GaN) wafers using an annular slicer results in a high slicing margin, leading to inefficiency and waste, as approximately 60% to 70% of the ingot is discarded as cutting margin.
Innovation Solution
A manufacturing method involving a pulsed laser beam is used to form a separation layer within the ingot, allowing for precise separation of wafers with a controlled thickness, reducing the slicing margin by forming the layer at a predetermined depth and moving the focal points in specific patterns to create a separation layer that enables efficient wafer separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a cutting blade is used to slice the ingot, then the wafer can be separated from the ingot, but the slicing margin becomes large leading to high material waste
Solution Approach 1:
The patent replaces the mechanical cutting blade system with a laser-based system. The laser beam creates a separation layer through optical-thermal interaction with the material, eliminating the need for mechanical contact and the associated large cutting margins required for blade thickness and safety clearances
Solution Approach 2:
The patent changes the fundamental parameter of separation from mechanical force to optical energy concentration. By focusing the laser beam to a specific depth within the ingot, the separation layer is created at a precise location without the material removal inherent in mechanical slicing, thereby reducing slicing margin
2Loss of substance
If the cutting blade thickness is reduced, then the slicing margin decreases, but the blade strength and durability are compromised
Solution Approach 1:
The patent eliminates the mechanical cutting blade entirely and replaces it with a non-contact laser system. This substitution removes the trade-off between blade thickness and strength, as the laser beam has no physical dimensions and requires no structural strength to perform the cutting function
3Productivity
If the ingot is sliced into thinner wafers, then the productivity increases, but the slicing margin percentage increases leading to more waste
Solution Approach 1:
The laser-based separation system enables precise control over wafer thickness without the material waste inherent in mechanical slicing. The laser creates separation layers at exact depths, allowing thin wafers to be produced with minimal slicing margin, thereby improving both productivity and material utilization efficiency
Solution Approach 2:
The laser creates a separation layer in advance at the precise desired depth before the actual wafer separation occurs. This preliminary action allows for exact thickness control and minimizes the slicing margin required, enabling high productivity with reduced material waste
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 significantly reduces the slicing margin, improving the productivity of wafer manufacturing by allowing for thinner wafers to be produced with less material waste compared to traditional cutting blade methods.
Implementation Method 1
applying a pulsed laser beam with such a wavelength as to be transmitted through the workpiece to the first surface from a side opposite to the second surface, and with a focal point of the laser beam positioned at a predetermined depth level in the workpiece
Implementation Method 2
applying a pulsed laser beam... to the first surface... thereby forming a separation layer in the workpiece
Implementation Method 3
a holding step of holding the workpiece at the second surface thereof under suction
Data Source
AI summary
A manufacturing method of a wafer from a workpiece, the workpiece being an ingot of gallium nitride or a single-crystal substrate of gallium nitride having both a first surface and a second surface. The method includes a separation layer forming step of applying a pulsed laser beam with such a wavelength as to be transmitted through the workpiece to the first surface, and with a focal point of the laser beam positioned at a predetermined depth level in the workpiece, relatively moving the workpiece and the focal point along a predetermined direction, thereby forming a separation layer in the workpiece, and a separation step of separating the wafer from the workpiece using the separation layer as a start point. The predetermined direction forms, in a (0001) plane, an angle of 5° or smaller with respect to crystal orientations represented by the following Miller-Bravais indices (1).[Math.1]1120 (1)