8-Inch SiC Substrate Growth With Temperature Gradient Control
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Solution Overview
Problem
The challenge lies in producing 8-inch SiC single crystal substrates with comparable quality to 6-inch substrates, as larger sizes face issues such as thermal decomposition, macro defects, and increased dislocation density due to inadequate manufacturing conditions, leading to lower yield and quality in mass production.
Innovation Solution
The solution involves controlling temperature gradients in both radial and vertical directions during crystal growth using a heat-insulating member that can move along the guide member, optimizing the shape of the isothermal surface to reduce defects, and employing a novel lapping slurry for precise thickness variation, resulting in substrates with reduced SORI, micropipe defects, and dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manufacturing conditions optimized for 6-inch substrates are applied to 8-inch substrates, then production efficiency increases, but dislocation density increases and crystal quality deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting manufacturing conditions specifically for 8-inch substrates, including controlling temperature gradients in radial and vertical directions, optimizing crystal growth rates, and adjusting substrate orientation angles to achieve low dislocation density in large-diameter substrates
Solution Approach 2:
The patent employs dynamics by implementing dynamic control of temperature distribution and crystal growth conditions during the manufacturing process, allowing real-time adjustment of growth parameters to maintain optimal conditions throughout the formation of 8-inch substrates
2Productivity
If the diameter of SiC single crystal substrates is increased from 6 inch to 8 inch, then production efficiency and cost reduction improve, but thermal decomposition occurs around the outer peripheral portion of the seed crystal causing macro defects
Solution Approach 1:
The patent applies local quality by implementing position-dependent temperature control, where the temperature gradient is specifically optimized for different radial zones of the 8-inch substrate, ensuring adequate heat dissipation at the outer peripheral portions to prevent thermal decomposition while maintaining crystal quality
Solution Approach 2:
The patent introduces another dimension by controlling temperature gradients not only in the radial direction but also in the vertical direction, creating a three-dimensional temperature distribution optimization that prevents thermal decomposition at the periphery while enabling large-diameter substrate production
3Productivity
If the diameter of SiC single crystal substrates is increased from 6 inch to 8 inch, then production efficiency improves, but yield reduction occurs due to macro defects
Solution Approach 1:
The patent applies preliminary action by pre-optimizing the seed crystal configuration and initial temperature distribution before starting crystal growth, ensuring that conditions are set to prevent macro defect formation from the beginning of the process, thereby maintaining high yield in 8-inch substrates
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 enables the production of 8-inch SiC single crystal substrates with improved quality, reduced SORI, in-plane thickness variation, and lower defect densities, enhancing the yield and quality of large-diameter substrates beyond what is achievable with standard 6-inch manufacturing techniques.
Implementation Method 1
controlling the temperature gradients in both radial and vertical directions during crystal growth using a heat-insulating member
Implementation Method 2
controlling the temperature gradients in both radial and vertical directions during crystal growth
Implementation Method 3
using a specific lapping slurry to reduce work-affected layer depth
Implementation Method 4
during crystal growth
Data Source
AI summary
An 8-inch SiC single crystal substrate of an embodiment has a diameter in a range of 195 mm to 205 mm, a thickness in a range of 300 μm to 650 μm, a SORI of 50 μm or less, and an in-plane variation of the thickness of the substrate, which is the difference between the maximum and minimum substrate thickness at the center of the substrate and four points on the circumference of a circle having a radius half the radius of the substrate, is 1.5 μm or less.