SiC Substrate Off-Angle Photoluminescence Control
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Solution Overview
Problem
Semiconductor devices using silicon carbide substrates often exhibit high reverse leakage current, which is undesirable.
Innovation Solution
A silicon carbide substrate with a hexagonal crystal structure and a main surface inclined at an off angle from the {0001} plane, where the number of photoluminescent emitting regions per unit area is limited to reduce reverse leakage current, is used in conjunction with a method of manufacturing that involves measuring and removing defective regions to minimize reverse leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a silicon carbide substrate is used to manufacture semiconductor devices, then high breakdown voltage and low on-resistance are achieved, but reverse leakage current increases
Solution Approach 1:
The patent applies local quality by specifying precise photoluminescence characteristics for different regions of the silicon carbide substrate. By controlling the number and size of emitting regions with wavelength exceeding 650 nm in specific areas, the substrate achieves both high breakdown voltage and reduced reverse leakage current. The off-angle orientation (0.5-5 degrees) also creates local structural variations that improve device performance while minimizing harmful leakage effects.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the photoluminescence wavelength threshold (650 nm) and the density of emitting regions (controlling the number of regions with specific dimensions). By adjusting these parameters during substrate manufacturing and selection, the invention achieves the desired balance between high breakdown voltage capability and low reverse leakage current in the semiconductor devices.
2Object-generated harmful factors
If photoluminescence measurement is performed to identify defective regions, then reverse leakage current is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by performing photoluminescence measurement on the silicon carbide substrate before device fabrication. This allows defective regions to be identified and excluded in advance, ensuring that only high-quality substrate areas are used for manufacturing. The measurement criterion (emitting regions with wavelength >650 nm) is established beforehand, streamlining the quality control process.
Solution Approach 2:
The patent replaces complex mechanical or chemical defect detection methods with optical photoluminescence measurement. This substitution simplifies the manufacturing process by using non-destructive optical inspection to identify defective regions, avoiding the need for more complex mechanical testing or chemical analysis procedures while effectively reducing reverse leakage current.
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
The approach effectively reduces reverse leakage current in semiconductor devices, enhancing their performance by minimizing defective regions and optimizing the substrate's photoluminescence characteristics.
Implementation Method 1
the number of those having a dimension of at most 15 μm in a direction perpendicular to the off direction and a dimension in a direction parallel to the off direction not larger than a value obtained by dividing penetration length of the excitation light in the hexagonal silicon carbide by a tangent of the off angle is at most 1 × 10 4
Data Source
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AI summary
A silicon carbide substrate (80), comprising: a side surface (SD); and a main surface (M80) surrounded by said side surface; wherein said silicon carbide substrate has a hexagonal crystal structure; said main surface is inclined by an off angle in an off direction from {0001} plane of said hexagonal crystal (HX); and said main surface has such a characteristic that, among the regions emitting photoluminescent light (LL) having a wavelength exceeding 650 nm of said main surface caused by excitation light (LE) having higher energy than band-gap of the hexagonal silicon carbide, the number of those having a dimension of at most 15 µm in a direction perpendicular to said off direction and a dimension in a direction parallel to said off direction not larger than a value obtained by dividing penetration length of said excitation light in the hexagonal silicon carbide by a tangent of said off angle is at most 1 × 104 per 1 cm2.