Silicon Carbide Substrate Wire Saw Cutting Direction Optimization
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Solution Overview
Problem
The existing methods for manufacturing silicon carbide substrates often result in flaws such as cracks and saw marks, and high Surface Roughness Index (SORI), which affect the quality and efficiency of silicon carbide substrates, epitaxial substrates, and semiconductor devices.
Innovation Solution
A method involving cutting a silicon carbide ingot with a polytype of 4H—SiC using a wire saw, where the ingot is cut from the side surface at a (000-1) plane side along a direction within ±5° relative to the bisector of the [1-100] and [11-20] directions, with a linear velocity of at least 1000 m/minute, wire tension less than 70% of the breaking tension, and diamond abrasive grains of less than 50 μm in size, to reduce SORI and flaws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wire saw cutting methods are used on silicon carbide ingots, then the cutting process can be completed, but the substrate develops flaws such as cracks and saw marks with high SORI
Solution Approach 1:
The patent applies parameter changes by optimizing multiple cutting parameters simultaneously: wire linear velocity (≥1000 m/min), wire tension (≤70% of breaking tension), wire diameter (≤200 μm), abrasive grain size (≤50 μm), and cutting direction (within ±5° of the bisector direction). These parameter changes resolve the contradiction by achieving high manufacturing precision while maintaining ease of manufacture through systematic optimization rather than process complexity
Solution Approach 2:
The patent employs dynamics by making the wire movable at high linear velocity (≥1000 m/min) during cutting, rather than keeping both wire and ingot stationary. This dynamic approach allows the cutting process to achieve precise results with reduced flaws and SORI, resolving the contradiction between manufacturing precision and ease of manufacture
2Productivity
If the wire linear velocity is increased to reduce cutting time, then productivity improves, but the risk of substrate damage increases
Solution Approach 1:
The patent resolves this contradiction through parameter changes by setting the wire linear velocity to at least 1000 m/min while simultaneously optimizing other parameters: wire tension at ≤70% of breaking tension, wire diameter ≤200 μm, and abrasive grain size ≤50 μm. This coordinated parameter optimization achieves high productivity while maintaining substrate integrity, preventing the damage that would normally result from high-speed cutting
3Manufacturing precision
If the wire tension is increased to maintain wire stability during cutting, then cutting precision improves, but the wire may break reducing productivity
Solution Approach 1:
The patent resolves this contradiction by optimizing wire tension to be at most 70% of the breaking tension, rather than using maximum tension. This parameter optimization maintains sufficient wire stability for precise cutting (±5° directional accuracy) while preventing wire breakage, thereby ensuring both manufacturing precision and continuous productivity
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 approach reduces SORI and flaws in silicon carbide substrates, leading to improved processing time, reduced damage, and enhanced yield in silicon carbide epitaxial substrates and semiconductor devices.
Implementation Method 1
A diamond abrasive grain is fixed to the wire. A grain size of the diamond abrasive grain is less than or equal to 50 μm.
Data Source
AI summary
A silicon carbide ingot is cut using a wire. The silicon carbide ingot has a polytype of 4H—SiC. The silicon carbide ingot includes a top surface, a bottom surface opposite to the top surface, and a side surface between the top surface and the bottom surface. A direction from the bottom surface toward the top surface is a direction parallel to a [0001] direction or a direction inclined by less than or equal to 8° relative to the [0001] direction. In the cutting of the silicon carbide ingot, the silicon carbide ingot is cut from the side surface at a (000-1) plane side along a straight line parallel to a direction within ±5° relative to a direction that bisects an angle formed by a [1-100] direction and a [11-20] direction when viewed in the direction from the bottom surface toward the top surface.