Silicon Carbide Substrate Production via Deposition and Chemical Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing silicon carbide substrates face challenges in achieving smoothness and reducing internal stress, with issues such as thermal roughening, carbonization, and incorporation of impurities, while maintaining mechanical strength and chemical durability.
Innovation Solution
A method involving the deposition of polycrystalline silicon carbide films on a support substrate with covering layers of silicon oxide, silicon nitride, or silicide, followed by chemical removal of the covering layers to obtain substrates with smooth surfaces and reduced internal stress, using vapor deposition or liquid phase growth methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical-mechanical polishing (CMP) is applied onto a surface of a polycrystalline silicon carbide substrate to obtain a smooth surface, then the surface smoothness is improved, but the polishing rates and etching rates differ in the respective faces and planes causing impairment of smoothness
Solution Approach 1:
The invention changes the fundamental approach from mechanical/chemical removal (CMP) to physical deposition. By using vapor phase deposition or liquid phase growth methods, a new polycrystalline silicon carbide layer is formed on the substrate surface, inheriting the smoothness of the underlying flat surface without suffering from the anisotropic removal rates that plague CMP processes on polycrystalline materials with mixed orientations.
2Strength
If a single crystal silicon carbide substrate is used to achieve high mechanical strength and heat resistance, then the substrate performance is improved, but the production cost becomes high and dislocation glide causes deformation during thermal processes
Solution Approach 1:
The invention applies local quality by creating a thin film of single crystal silicon carbide (3-10 μm thick) on an inexpensive polycrystalline silicon carbide substrate. The single crystal layer provides the required mechanical strength, heat resistance, and radiation resistance at the surface where these properties are critical, while the polycrystalline bulk substrate provides structural support at lower cost and with better thermal stability due to grain boundary dislocation blocking.
3Strength
If the surface of a polycrystalline silicon carbide substrate is irradiated with a neutral atom beam of argon to form an amorphous layer for bonding, then bonding strength is improved, but the surface roughness becomes larger and special treatment is required
Solution Approach 1:
The invention performs preliminary action by forming a very smooth polycrystalline silicon carbide surface (Ra ≤ 1 nm) through vapor phase or liquid phase deposition before bonding is required. This pre-formed smooth surface eliminates the need for subsequent argon ion beam treatment that would increase roughness, while still enabling strong bonding through the smooth interface.
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 silicon carbide substrates with improved smoothness (arithmetic mean roughness Ra of 0.3 nm or less) and reduced internal stress, without the complications of thermal etching or impurity incorporation, enhancing their mechanical and chemical properties.
Implementation Method 1
forming polycrystalline silicon carbide films on both surfaces of the support substrate by a vapor deposition method or a liquid phase growth method
Implementation Method 2
forming polycrystalline silicon carbide films on both surfaces of the support substrate by a vapor deposition method or a liquid phase growth method
Implementation Method 3
chemically removing at least the covering layers in the support substrate to separate the polycrystalline silicon carbide films from the support substrate
Data Source
AI summary
A silicon carbide substrate production method includes: the step of providing covering layers 1b, 1b, each containing silicon oxide, silicon nitride, silicon carbonitride, or silicide, respectively on both surfaces of a base material substrate 1a carbon, silicon or silicon carbide, and turning the surface of each of the covering layers 1b, 1b into a smooth surface to prepare a support substrate 1; a step of forming a polycrystalline silicon carbide film 10 on both surfaces of the support substrate 1 by a gas phase growth method or a liquid phase growth method; and a step of separating the polycrystalline silicon carbide films from the support substrate while preserving, on the surface thereof, the smoothness of the covering layer surfaces 1b, 1b by chemically removing at least the covering layers 1b, 1b, from the support substrate 1. The silicon carbide substrate has a smooth surface and reduced internal stress.