SiC Substrate Homogeneous Resistance via Lateral Temperature Gradient Control
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Solution Overview
Problem
Conventional sublimation growth methods for SiC single crystals result in inhomogeneous dopant distribution and resistance fluctuations, leading to low-quality semiconductor components due to the formation of facet, transition, and edge regions with different dopant concentrations and surface structures.
Innovation Solution
A method is developed to produce bulk SiC single crystals with a large facet region by adjusting the lateral temperature gradient to at most 2 K/cm, ensuring the facet region covers at least 90% of the growth interface, and optimizing dopant addition to achieve uniform electrical resistance, thereby eliminating the need for recessing the facet region and reducing defect density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sublimation growth is used to produce bulk SiC single crystals, then crystal growth can be achieved, but inhomogeneous dopant distribution and resistance fluctuations occur due to facet, transition, and edge region formation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the lateral temperature gradient (maintaining it below 2 K/cm) and adjusting dopant feed rates during crystal growth. This control of thermal and compositional parameters ensures uniform dopant distribution across the entire growth interface, eliminating the facet/transition/edge region differentiation that causes resistance fluctuations and component quality issues.
2Manufacturing precision
If growth conditions are optimized for the edge region to achieve desired dopant concentration, then edge region quality improves, but the facet region becomes too highly doped and unusable for component production
Solution Approach 1:
The patent applies local quality by maintaining different dopant feed rates in different radial zones of the growth interface. By controlling the lateral temperature gradient and using zone-specific dopant introduction, the method achieves desired dopant concentration in the edge region while preventing excessive doping in the facet region, making the entire crystal cross-section usable for high-quality component production.
3Area of stationary object
If a large facet region is produced to increase substrate area, then more components can be manufactured, but conventional methods create inhomogeneous resistance distribution across the substrate
Solution Approach 1:
The patent resolves this contradiction by implementing precise parameter control of the lateral temperature gradient (kept below 2 K/cm) and dopant feed rates throughout the growth process. This ensures that even across a large substrate area, the dopant concentration remains uniform, producing resistance distribution homogeneity that enables high-quality component fabrication over the entire large substrate surface.
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 bulk SiC single crystals with homogeneous resistance distribution, enhancing the quality and efficiency of semiconductor component production by preventing strong resistance fluctuations and reducing defect density, leading to higher-quality SiC substrates suitable for large-scale semiconductor components.
Implementation Method 1
The bulk SiC single crystal having a central longitudinal mid-axis grows by deposition from the SiC growth gas phase, the deposition taking place on a growth interface of the growing bulk SiC single crystal
Implementation Method 2
an SiC growth gas phase is produced in the crystal growth region. The bulk SiC single crystal grows by deposition from the SiC growth gas phase
Data Source
AI summary
A method is used to produce a bulk SiC single crystal. A seed crystal is arranged in a crystal growth region of a growing crucible. An SiC growth gas phase is produced in the crystal growth region. The bulk SiC single crystal having a central longitudinal mid-axis grows by deposition from the SiC growth gas phase, the deposition taking place on a growth interface of the growing bulk SiC single crystal. The SiC growth gas phase is at least partially fed from an SiC source material and contains at least one dopant from the group of nitrogen, aluminum, vanadium and boron. At least in a central main growth region of the growth interface arranged about the longitudinal mid-axis, a lateral temperature gradient of at most 2 K/cm measured perpendicular to the longitudinal mid-axis is adjusted and maintained in this range. The bulk SiC single crystal has a large facet region.