Laser Wafer Separation With Rotating Lens for SiC and GaN Ingots
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Solution Overview
Problem
The existing methods for manufacturing wafers, particularly from high-hardness materials like SiC and GaN, are inefficient due to high material wastage and low productivity, as they require significant time and resources for cutting and polishing, and forming dense modified layers with current laser techniques is time-consuming.
Innovation Solution
A wafer manufacturing apparatus that includes a holding table, a laser beam application unit with a condenser lens and rotating mechanism to form modified layers inside an ingot efficiently, allowing for precise positioning and rotation of the laser beam to create layers at the required depth and orientation for wafer separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a wire saw is used to cut the ingot, then the wafer can be manufactured, but 70% to 80% of the ingot is thrown away and processing time is considerable
Solution Approach 1:
The patent replaces the mechanical wire saw cutting system with a laser-based modified layer formation system. The laser beam creates modified layers inside the ingot that enable wafer separation without mechanical cutting, thereby eliminating the 70-80% material wastage associated with wire saw cutting while maintaining manufacturing capability.
Solution Approach 2:
The patent changes the physical state and properties of the ingot material by forming modified layers through laser irradiation. This parameter change allows the ingot to be separated into wafers along predetermined planes without mechanical cutting, resolving the contradiction between reducing material wastage and maintaining productivity.
2Manufacturing precision
If modified layers are formed densely with 10 μm interval, then wafer separation is enabled, but it takes considerable time to form the modified layers
Solution Approach 1:
The patent introduces rotation of the ingot during laser processing, adding a rotational dimension to the modified layer formation. This allows multiple modified layers to be formed simultaneously at different angular positions around the ingot circumference, thereby maintaining the required 10 μm density while significantly reducing the total processing time.
Solution Approach 2:
The patent performs preliminary positioning and planning of modified layer locations before actual laser processing. By pre-determining the optimal paths and parameters for modified layer formation, the system achieves high-density layer formation with minimized processing time through efficient laser beam utilization.
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 apparatus enables the efficient formation of modified layers within the ingot, reducing processing time and improving productivity by allowing for precise and parallel formation of arcuate modified layers, thereby enhancing the wafer production efficiency and minimizing material wastage.
Implementation Method 1
a wafer manufacturing unit that applies such a laser beam as to be transmitted through the ingot to the ingot, with a focal point of the laser beam positioned inside the ingot, to form a modified layer
Implementation Method 2
a condenser lens that concentrates the laser beam emitted by the laser oscillator, to the inside of the ingot
Data Source
AI summary
A wafer manufacturing apparatus includes a holding table that holds an ingot, a wafer manufacturing unit that applies such a laser beam as to be transmitted through the ingot to the ingot, with a focal point of the laser beam positioned inside the ingot, to form a modified layer at a depth corresponding to the thickness of a wafer to be manufactured, and a moving mechanism that moves the holding table and the wafer manufacturing unit relative to each other. The wafer manufacturing unit includes a laser oscillator that emits the laser beam, a condenser lens that concentrates the laser beam emitted by the laser oscillator, to the inside of the ingot, and a rotating mechanism that rotates the condenser lens in parallel to an end face of the ingot.