SiC Wafer Peel-Off Layering for Low-Waste Ingot Separation
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Solution Overview
Problem
The existing methods for manufacturing wafers from silicon carbide (SiC) ingots are inefficient and wasteful, as they result in significant material loss during slicing and polishing, leading to high production costs and low productivity.
Innovation Solution
A wafer manufacturing method using a laser beam to create peel-off layers and separating walls within the ingot, allowing for the efficient separation of larger and smaller diameter wafers without grinding, thereby minimizing material waste and reducing the need for subsequent polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wire saw slicing and polishing processing is used to manufacture wafers from SiC ingots, then wafers can be produced with smooth surfaces, but 70% through 80% of the ingot material is wasted
Solution Approach 1:
The invention divides the ingot into multiple usable wafers by creating internal separating structures (peel-off layers and separating walls) that allow sequential extraction of wafers with different diameters from the same ingot, thereby segmenting the material utilization into multiple productive stages rather than losing material in single-pass processing
Solution Approach 2:
The peel-off layers and separating walls are formed in advance within the ingot using laser processing before wafer extraction. This preliminary structuring enables subsequent easy separation and maximizes material utilization by pre-defining where wafers will be extracted without requiring excessive material removal
2Productivity
If wire saw slicing is used to cut SiC ingots, then wafers can be separated, but the hard SiC material causes poor productivity and high unit price
Solution Approach 1:
The invention replaces the mechanical wire saw cutting process with laser processing to create peel-off layers and separating walls. The laser method avoids the difficulties of mechanically cutting hard SiC material, enabling faster and more efficient wafer extraction without the productivity losses associated with wire saw processing
Solution Approach 2:
The invention changes the processing method from mechanical cutting to thermal/laser processing. By using laser energy to create internal separating structures, the process bypasses the limitations of mechanical cutting on hard materials like SiC, achieving both higher productivity and easier manufacture
3Length of moving object
If the reverse side of a wafer is ground to reduce thickness from 800 μm to 50-100 μm, then the desired thin wafer thickness is achieved, but at least 700 μm of wafer material is wasted
Solution Approach 1:
The peel-off layers are formed in advance at the desired wafer thickness positions within the ingot. This allows wafers to be extracted at the correct thickness without requiring subsequent grinding that would waste 700 μm or more of material, as the thinning is achieved during the extraction process itself
4Quantity of substance
If a larger-diameter wafer is fabricated from an SiC ingot, then more material is utilized, but smaller-diameter wafers cannot be efficiently produced from the same ingot
Solution Approach 1:
The invention segments the ingot material utilization into multiple stages: first extracting a large-diameter wafer, then extracting smaller-diameter wafers from the remaining material. The peel-off layers and separating walls enable this multi-stage extraction, making the ingot adaptable to produce different wafer sizes sequentially
Solution Approach 2:
The same ingot and laser processing system can produce multiple types of wafers (different diameters and thicknesses) from a single material source. The process is universal and can be adjusted to produce whatever wafer dimensions are needed, maximizing the versatility and material utilization of each ingot
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 enables the economical production of wafers by minimizing material waste and allowing for further processing of smaller wafers into even smaller ones, thus optimizing the use of ingot material and reducing production costs.
Implementation Method 1
forming a first peel-off layer in the ingot by applying a laser beam having a wavelength transmittable through the ingot while positioning a focused spot of the laser beam in the ingot
Implementation Method 2
forming a first peel-off layer in the ingot by applying a laser beam having a wavelength transmittable through the ingot while positioning a focused spot of the laser beam in the ingot at a first depth
Implementation Method 3
forming an annular first separating wall along an outer circumferential edge of the smaller-diameter wafer by applying the laser beam to the ingot while positioning the focused spot on an annular area extending from an end face of the ingot to the second peel-off layer
Data Source
AI summary
A wafer manufacturing method includes forming a first peel-off layer in an ingot by applying a laser beam with a focused spot of the laser beam in the ingot at a first depth from an end face of the ingot for fabricating a larger-diameter wafer, forming a second peel-off layer in the ingot for fabricating a smaller-diameter wafer by applying the laser beam to an area of the ingot that is smaller in diameter than the ingot while positioning the focused spot in the ingot at a second depth, which is smaller than the first depth, from the end face of the ingot, and forming an annular first separating wall along an outer circumferential edge of the smaller-diameter wafer by applying the laser beam to the ingot while positioning the focused spot on an annular area extending from the end face of the ingot to the second peel-off layer.