Silicon Carbide Substrate Polishing with Permanganate Ions
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Solution Overview
Problem
The quality of semiconductor layers formed by epitaxial growth on silicon carbide substrates is compromised by linear etch-pit groups, even if the substrate surface is smooth, due to damage from existing chemical mechanical polishing methods, which affects the formation of high-quality semiconductor devices like diodes and transistors.
Innovation Solution
A silicon carbide substrate is produced using a chemical mechanical polishing method with a polishing liquid containing a permanganate ion concentration greater than 5% by mass, which increases the oxidation rate and reduces the formation of linear etch-pit groups, ensuring a high-quality semiconductor layer by suppressing abrasive-induced damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional chemical mechanical polishing is used to smooth the substrate surface, then surface smoothness is improved, but linear etch-pit groups are formed due to abrasive damage
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing liquid by specifying a permanganate ion concentration of 5% by mass or more. This chemical parameter change transforms the polishing mechanism from primarily mechanical abrasion to chemical oxidation, thereby achieving surface smoothing without forming linear etch-pit groups caused by abrasive damage
Solution Approach 2:
The patent replaces the mechanical polishing action with a chemical oxidation process. By using a polishing liquid containing permanganate ions, the surface smoothing function is achieved through chemical means rather than mechanical abrasion, eliminating the harmful mechanical damage that creates linear etch-pit groups
2Manufacturing precision
If polishing is performed to ensure surface smoothness for epitaxial growth, then semiconductor layer quality is improved, but substrate damage occurs from polishing abrasives
Solution Approach 1:
The patent modifies the chemical parameters of the polishing liquid by设定 permanganate ion concentration at 5% by mass or more. This parameter change shifts the polishing mechanism from mechanical to chemical, preserving substrate integrity while achieving the surface smoothness required for high-quality semiconductor layer formation
Solution Approach 2:
The patent substitutes mechanical abrasion with chemical oxidation using permanganate ions. This replacement eliminates mechanical damage to the substrate while still achieving the necessary surface smoothness for high-quality epitaxial growth of semiconductor layers
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 method effectively reduces the overall length of linear etch-pit groups to be equal to or less than the substrate diameter, enabling the formation of high-quality semiconductor layers suitable for manufacturing semiconductor devices with improved yield and reliability.
Implementation Method 1
a polishing liquid having a permanganate ion concentration of more than 5% by mass, which increases the oxidation rate
Implementation Method 2
when a main surface thereof is etched with chlorine gas, the overall length of linear etch-pit groups observed in the main surface
Data Source
AI summary
A silicon carbide substrate is composed of silicon carbide, and when a main surface thereof is etched with chlorine gas, the overall length of linear etch-pit groups observed in the main surface is equal to or less than the diameter of the substrate.