SiC Substrate Defect Management for 8-Inch Yield
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Solution Overview
Problem
The challenge in manufacturing large-diameter SiC single crystal substrates is achieving the same quality as smaller substrates, as new problems arise with increased size, such as thermal decomposition and macro defects, which affect crystal quality and yield.
Innovation Solution
A SiC single crystal substrate with specific off-angles and the inclusion of non-MP defects, which are hexagonal, coreless, and have etch pit areas within certain proportions of TSD and micropipe etch pits, are introduced to manage dislocation density and stress relaxation, thereby improving ion implantation outcomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter of SiC single crystal substrates is increased from 6 inch to 8 inch to improve productivity and reduce costs, then manufacturing efficiency and cost-effectiveness are improved, but new problems arise such as thermal decomposition around the outer peripheral portion of the seed crystal and macro defects that deteriorate crystal quality
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the seed crystal within a specific range (0.5mm to 2.0mm) and controlling the temperature gradient during crystal growth. By adjusting these parameters, the invention enables successful growth of 8-inch substrates while preventing thermal decomposition and macro defects, thus resolving the contradiction between increased productivity and maintained crystal quality.
2Ease of manufacture
If manufacturing conditions optimized for 6-inch substrates are applied to 8-inch substrates to maintain ease of manufacture, then manufacturing simplicity is maintained, but the same quality cannot be obtained due to new problems arising with increased size
Solution Approach 1:
The patent applies local quality by implementing size-specific manufacturing conditions. For 8-inch substrates, it specifies particular seed crystal thickness ranges (0.5mm to 2.0mm) and controlled temperature gradients that differ from 6-inch substrate manufacturing. This localized optimization maintains ease of manufacture through standardized procedures while achieving the manufacturing precision required for larger substrates.
3Stability of the object's composition
If the thickness of the seed crystal is increased to prevent thermal decomposition in 8-inch substrates, then thermal stability is improved, but the complexity of the manufacturing process increases due to stricter control requirements
Solution Approach 1:
The patent resolves this contradiction by defining a specific parameter range for seed crystal thickness (0.5mm to 2.0mm) that provides adequate thermal stability while avoiding excessive complexity. Within this optimized range, the manufacturing process achieves reliable thermal management without requiring overly complex control systems, balancing stability and complexity through precise parameter specification.
Data Source
AI summary
A SiC single crystal substrate of an embodiment is a SiC single crystal substrate wherein the main plane of the SiC single crystal substrate has an off angle of 0° to 6° to the (0001) plane in the <11-20> direction and an off angle of 0° to 0.5° to the (0001) plane in the <1-100> direction, and includes non-MP defects wherein when the Si surface is etched in molten KOH at 500° C. for 15 minutes, the non-MP defects that appear by etching are hexagonal and have no core, the area of the observed etch pit of the non-MP defect is more than 10% larger than that of the observed etch pit of the TSD and is less than 110% of that of the observed etch pit of the micropipe (MP), and a transmission X-ray topography image of the non-MP defect is distinguishable from the transmission X-ray topography image of the micropipe (MP), wherein etch pits, which are identified as the non-MP defects, appear in the range of 0.1/cm2 to 50/cm2.