SiC Single Crystal Growth via Low-Vanadium Sublimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing high resistivity silicon carbide (SiC) single crystals face challenges in achieving high crystal quality and large size due to limitations in controlling vanadium concentration and crystal purity, leading to low yield and high manufacturing costs.
Innovation Solution
The method involves using a sublimation recrystallization process with a graphite crucible having a low nitrogen concentration, treated in an inert gas atmosphere, to grow SiC single crystals with a specific vanadium and uncompensated impurity concentration, allowing for high resistivity and improved crystal quality without excessive vanadium addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanadium is added to increase electrical resistivity, then resistivity is improved, but crystal quality deteriorates due to precipitation and defects
Solution Approach 1:
The patent changes the concentration parameter of vanadium from high levels (conventional addition) to low levels (0.01-0.1 at%), and simultaneously changes the nitrogen concentration parameter to low levels (0.001-0.1 at%), creating a specific parameter combination that achieves high resistivity without crystal quality degradation
Solution Approach 2:
The patent creates a specific local composition environment by controlling both vanadium and nitrogen concentrations to be low, establishing a localized compositional regime that prevents vanadium precipitation while maintaining high electrical resistivity
2Area of stationary object
If sublimation recrystallization method is used to grow large area single crystal, then area is improved, but control of crystal polytypes and impurity concentration becomes difficult
Solution Approach 1:
The patent changes the impurity concentration parameters (vanadium and nitrogen) to specific low values during the sublimation recrystallization process, enabling control of crystal polytypes and impurity concentration while maintaining large area growth capability
Solution Approach 2:
The patent employs controlled atmosphere conditions and temperature gradients during sublimation recrystallization that provide feedback control over the crystallization process, allowing precise control of polytypes and impurity incorporation while growing large area crystals
3Reliability
If high vanadium concentration is used to achieve high resistivity, then resistivity is improved, but manufacturing cost increases due to low yield
Solution Approach 1:
The patent changes the vanadium concentration parameter to a low level (0.01-0.1 at%) that prevents precipitation and crystal defects, thereby improving crystal yield and quality while still achieving the required electrical resistivity through the combined effect of low vanadium and low nitrogen concentrations
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 enables the production of high resistivity SiC single crystals and wafers with improved crystal quality and reduced manufacturing costs, achieving resistivity of at least 5×10^3 Ωcm and maintaining high yield, while avoiding the issues of vanadium precipitation and crystal quality degradation.
Implementation Method 1
a method of production of a silicon carbide single crystal by using a sublimation recrystallization method using a seed crystal
Implementation Method 2
using for the crystal growth a graphite crucible having a nitrogen concentration of not more than 50 ppm as measured by an inert gas fusion thermal conductivity method
Data Source
AI summary
The present invention provides a high resistivity, high quality, large size SiC single crystal, SiC single crystal wafer, and method of production of the same, that is, a silicon carbide single crystal containing uncompensated impurities in an atomic number density of 1×1015/cm3 or more and containing vanadium in an amount less than said uncompensated impurity concentration, silicon carbide single crystal wafer obtained by processing and polishing the silicon carbide single crystal and having an electrical resistivity at room temperature of 5×103 Ωcm or more, and a method of production of a silicon carbide single crystal.