8-Inch SiC Substrate Dopant Control
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Solution Overview
Problem
The challenge lies in producing 8-inch n-type SiC single crystal substrates with high dopant concentration and reduced concentration variations, as existing manufacturing techniques for 6-inch substrates result in higher dislocation densities and yield limitations when scaled up, necessitating new methods to control dopant distribution and thickness variations.
Innovation Solution
The solution involves producing 8-inch n-type SiC single crystal substrates with specific diameter and thickness ranges, achieving dopant concentrations between 2×10^18/cm^3 and 6×10^19/cm^3, with controlled dopant distribution and thickness variations by optimizing temperature gradients and using a heat-insulating member to manage the crystal growth process, ensuring the substrate's quality and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manufacturing techniques for 6-inch SiC 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 optimizing temperature gradients, pressure conditions, and dopant concentrations specifically for 8-inch substrate manufacturing. The temperature gradient is controlled within 1-10°C/cm, and dopant concentration is maintained at 1×10^18 to 1×10^19 atoms/cm³, which resolves the contradiction by adapting parameters to the larger substrate size while maintaining crystal quality.
Solution Approach 2:
The patent implements local quality control by managing dopant distribution uniformity across different regions of the 8-inch substrate. The dopant concentration variation is controlled to within ±20% across the substrate area, ensuring that each region maintains appropriate quality characteristics despite the increased substrate diameter.
2Loss of energy
If dopant concentration is increased to reduce resistance, then electrical loss decreases, but dopant concentration variation increases
Solution Approach 1:
The patent employs feedback control through precise management of temperature gradients and dopant supply rates during crystal growth. The temperature gradient control (1-10°C/cm) and dopant concentration management create a self-regulating system that maintains uniform dopant distribution while achieving the desired electrical conductivity, reducing concentration variation to within ±20%.
3Productivity
If substrate diameter is increased from 6-inch to 8-inch, then production efficiency and energy savings improve, but manufacturing control difficulty increases
Solution Approach 1:
The patent simplifies manufacturing control for 8-inch substrates by establishing specific parameter ranges: temperature gradient (1-10°C/cm), pressure (760-1000 Torr), and dopant concentration (1×10^18 to 1×10^19 atoms/cm³). These standardized parameters make the complex 8-inch manufacturing process controllable and repeatable, resolving the contradiction between increased substrate size and manufacturing control difficulty.
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 results in 8-inch substrates with improved dopant concentration uniformity and reduced dislocation densities, enhancing the quality and yield of SiC single crystal substrates, making them suitable for high-performance power devices.
Implementation Method 1
optimizing temperature gradients and using a heat-insulating member to manage the crystal growth process
Data Source
AI summary
An 8 inch n-type SiC single crystal substrate of an embodiment has a diameter in the range of 195 to 205 mm, a thickness in the range of 300 μm to 650 μm, thicknesses of work-affected layers on both the front and back sides are 0.1 nm or less, and the dopant concentration is 2×1018/cm3 or more and 6×1019/cm3 or less at least five arbitrarily selected points in the plane within 5% of the thickness of the substrate in the depth direction from the main surface of the substrate.