SiC Substrate Defect Mapping for Threading Defect Identification
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Solution Overview
Problem
Current methods for evaluating SiC substrates are costly and time-consuming, particularly when inspecting multiple SiC devices, and they struggle to efficiently identify threading defects, which are major yield hindrances in SiC device manufacturing.
Innovation Solution
A method involving the preparation of multiple SiC substrates from the same ingot, specifying defect positions, and comparing these positions to determine if they are associated with the same threading defect, using criteria such as defect distance in specific directions to classify defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each SiC device is inspected individually using conventional methods, then defect detection accuracy is improved, but inspection time and cost increase significantly
Solution Approach 1:
The patent merges multiple individual substrate inspections into a single batch inspection process. Multiple SiC substrates are stacked together and inspected simultaneously using a single inspection device, allowing defect detection across all substrates in one operation rather than inspecting each substrate separately, thus improving throughput while maintaining detection accuracy
Solution Approach 2:
The inspection device is designed to perform universal inspection functions across multiple substrates simultaneously. The device can inspect different substrates with varying defect types (threading defects, micro-pipes, dislocations) using the same equipment and methodology, eliminating the need for separate inspection processes for each substrate
2Measurement precision
If additional separate inspection steps are added to identify threading defects, then defect specification accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines threading defect inspection with routine defect inspection into a single integrated process. By stacking multiple substrates and inspecting them together, the system simultaneously detects both threading defects and other defects without requiring separate inspection equipment or procedures, thereby reducing process complexity while maintaining high specification accuracy
Solution Approach 2:
The inspection method uses optical copying principles where light passes through the stacked substrates and defects are imaged onto a detection plane. This allows the inspection system to create optical copies of defect positions across multiple substrates, enabling accurate threading defect identification through image analysis without complex mechanical intervention
Data Source
AI summary
This method of evaluating a SiC substrate includes a preparation step of preparing two or more SiC substrates obtained from the same SiC ingot grown from the same seed crystal, a defect position specifying step of specifying positions of defects in the substrates by observing a main surface of each of the two or more SiC substrates, and a comparison step of comparing the positions of the defects of the two or more SiC substrates, in which, in the preparation step, a SiC substrate positioned closest to the seed crystal is used as a reference wafer among the two or more SiC substrates, and the comparison step comprises a sub-step wherein a first defect of the reference wafer is compared with a second defect of a SiC substrate other than the reference wafer, it is judged whether a defect distance of the two compared defects in a [11-20] direction is 0.6 mm or more or less than 0.2 mm, and the two compared defects are determined to be defects not associated with the same threading defect when the defect distance is 0.6 mm or more, and the two compared defects are determined to be defects associated with the same threading defect when the defect distance is less than 0.2 mm.