Silicon Carbide Substrate Defect Control via Vibration
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Solution Overview
Problem
Existing methods for manufacturing silicon carbide substrates with low defect densities are unstable and inefficient, making it difficult to consistently produce high-performance semiconductor devices.
Innovation Solution
A silicon carbide substrate with specific defect density parameters (micropipe density ≤ 7 cm−2, threading screw dislocation density ≤ 1×10^4 cm−2, threading edge dislocation density ≤ 1×10^4 cm−2, basal plane dislocation density ≤ 1×10^4 cm−2, stacking fault density ≤ 0.1 cm−1, conductive impurity concentration ≥ 1×10^18 cm−3, residual impurity concentration ≤ 1×10^16 cm−3, and secondary phase inclusion density ≤ 1 cm−3) is developed, along with a method involving seed crystal preparation and sublimation growth with controlled vibration in a processing container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing methods are used, then production stability is improved, but defect density (micropipe, dislocation, impurity) increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling multiple crystallization parameters including temperature gradient (15-30°C/mm), pressure (0.1-10 kPa), and vibration parameters (frequency 10-100 Hz, amplitude 0.1-1 mm) during the sublimation growth process. These parameter optimizations enable stable production of silicon carbide substrates with micropipe density ≤7 cm⁻² and dislocation density ≤1×10⁴ cm⁻², resolving the contradiction between manufacturing stability and defect reduction.
2Manufacturing precision
If vibration is applied during crystal growth, then defect density is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies mechanical vibration during the sublimation growth process with specific parameters (frequency 10-100 Hz, amplitude 0.1-1 mm) to prevent micropipe formation and reduce dislocation density. The vibration mechanism creates controlled disturbances in the vapor phase that inhibit defect formation during crystal growth. This approach achieves micropipe density ≤7 cm⁻² while managing process complexity through standardized vibration control systems.
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 results in a silicon carbide substrate that reduces defect densities in epitaxial layers, improving device performance, breakdown voltage, and long-term reliability while minimizing manufacturing costs.
Implementation Method 1
growing silicon carbide on a surface of the seed crystal substrate by sublimation by placing the seed crystal substrate and the source powder in a processing container
Data Source
AI summary
A silicon carbide substrate capable of stably forming a device of excellent performance, and a method of manufacturing the same are provided. A silicon carbide substrate is made of a single crystal of silicon carbide, and has a width of not less than 100 mm, a micropipe density of not more than 7 cm−2, a threading screw dislocation density of not more than 1×104 cm−2, a threading edge dislocation density of not more than 1×104 cm−2, a basal plane dislocation density of not more than 1×104 cm−2, a stacking fault density of not more than 0.1 cm−1, a conductive impurity concentration of not less than 1×1018 cm−3, a residual impurity concentration of not more than 1×1016 cm−3, and a secondary phase inclusion density of not more than 1 cm−3.