Ingot Wafer Separation Using Laser Crack Layers and Ultrasonic Peeling
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Solution Overview
Problem
The existing methods for manufacturing wafers from ingots, particularly those made of hard materials like SiC and GaN, face inefficiencies due to high material wastage and productivity issues, as well as damage during peeling due to immature crack layers formed by laser cutting.
Innovation Solution
A wafer manufacturing method involving the formation of a crack layer using a laser beam with a focal point positioned within the ingot, followed by a cut groove formation and ultrasonic peeling to remove immature crack layers, ensuring efficient and damage-free wafer separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is applied to form a crack layer at the periphery of the ingot, then the crack layer formation is completed, but the crack layer becomes immature and causes peeling failure
Solution Approach 1:
The patent extracts and removes the immature crack layer at the periphery of the ingot using a cutting blade. The cutting blade positions itself on the extension line of the crack layer and forms a cut groove that continuously removes the immature crack layer, preventing it from interfering with the peeling process and ensuring reliable wafer separation.
Solution Approach 2:
The patent performs preliminary removal of the immature crack layer before the peeling process. By forming the cut groove in advance to eliminate the defective peripheral crack layer, the patent ensures that subsequent peeling operations proceed without interference from immature cracks, thereby guaranteeing peeling success.
2Ease of manufacture
If wire saw cutting is used to slice the ingot, then wafers can be manufactured, but 70-80% of the ingot is discarded causing high material loss
Solution Approach 1:
The patent replaces the traditional wire saw mechanical cutting system with a laser-based crack layer formation system followed by controlled peeling. This substitution enables more efficient material utilization by creating a crack layer that allows for selective separation, significantly reducing the 70-80% material wastage associated with conventional wire saw cutting.
Solution Approach 2:
The patent utilizes the phase transition concept in the form of crack propagation. By applying laser energy to induce controlled cracking at specific depths, the material transitions from an intact state to a cracked state, enabling separation with minimal material loss. This approach contrasts with the complete removal of material layers in wire saw cutting.
3Productivity
If laser beam is focused inside the ingot to form crack layer, then cutting efficiency is improved, but the focal point positioning requires precise depth control
Solution Approach 1:
The patent employs feedback mechanisms to monitor and control the laser beam focal point depth. By implementing detection and control systems that provide real-time information about the crack layer formation progress, the system can adjust the focal point positioning to maintain optimal depth accuracy, ensuring high productivity without sacrificing precision.
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 effectively removes immature crack layers, preventing peeling issues and enabling efficient wafer production from ingots with reduced material wastage and improved productivity.
Implementation Method 1
applying a laser beam of such a wavelength as to be transmitted through the ingot to the ingot, with a focal point of the laser beam positioned in a region spaced from an end face of the ingot by a distance corresponding to a thickness of the wafer to be manufactured, to form a crack layer
Implementation Method 2
laser beam of such a wavelength as to be transmitted through the ingot
Implementation Method 3
applying an ultrasonic wave to the end face of the ingot to peel off the wafer to be manufactured, along the crack layer
Data Source
AI summary
A wafer manufacturing method includes: a crack layer forming step of applying a laser beam of such a wavelength as to be transmitted through an ingot to the ingot, with a focal point of the laser beam positioned in a region spaced from an end face of the ingot by a distance corresponding to the thickness of the wafer to be manufactured, to form a crack layer, a cut groove forming step of positioning a cutting blade on an extension line of the crack layer and forming a cut groove continuous with the crack layer in a periphery of the ingot; and a peeling step of applying an ultrasonic wave to the end face of the ingot to peel off the wafer to be manufactured, along the crack layer.