Silicon Carbide Substrate Polishing for Low-Pit Surface Cleanliness
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Solution Overview
Problem
Existing silicon carbide substrates face challenges in achieving high cleanliness due to the formation of pits and screw dislocations during chemical mechanical polishing, which are difficult to remove and affect the substrate's surface quality.
Innovation Solution
A silicon carbide substrate manufacturing method involving chemical mechanical polishing with a polishing liquid of high Brix value and subsequent treatment with an organic acid having two or more carboxy groups, such as oxalic acid or citric acid, to enhance the removal of metal impurities and reduce pit formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If chemical mechanical polishing is performed on silicon carbide substrate, then surface flatness is improved, but pits and screw dislocations are generated on the surface
Solution Approach 1:
The invention changes the chemical composition parameters of the polishing liquid by specifying a Brix value of 10 or more (high sugar content), which fundamentally alters the polishing mechanism to reduce mechanical stress and prevent pit formation while maintaining surface flatness improvement
Solution Approach 2:
The high Brix polishing liquid acts as an intermediary substance that mediates between the polishing cloth and substrate, providing enhanced lubrication to reduce direct mechanical contact and prevent the generation of pits and screw dislocations during the polishing process
2Ease of manufacture
If conventional polishing liquid is used, then polishing process is simple, but metal impurities remain on the surface
Solution Approach 1:
The invention changes the chemical composition of the polishing liquid by requiring a Brix value of 10 or more, which creates a polishing environment that inherently reduces metal impurity adhesion while maintaining process simplicity through a single liquid formulation
Solution Approach 2:
The polishing liquid is formulated as a composite material containing high concentrations of sugar (Brix ≥10) combined with appropriate polishing agents, creating a multi-functional liquid that simultaneously provides lubrication, cleaning, and contamination prevention
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 method effectively reduces the density and occurrence of pits and screw dislocations, improving the cleanliness and surface quality of the silicon carbide substrate by enhancing the lubricating action of the polishing liquid and utilizing the chelating action of organic acids to remove metal impurities.
Implementation Method 1
enhancing the lubricating action of the polishing liquid
Implementation Method 2
utilizing the chelating action of organic acids to remove metal impurities
Implementation Method 3
performing chemical mechanical polishing on the silicon carbide single-crystal substrate
Data Source
AI summary
A silicon carbide substrate has a first main surface and a second main surface opposite to the first main surface. The silicon carbide substrate includes screw dislocations and pits having a maximum diameter of 1 μm or more and 10 μm or less in a direction parallel to the first main surface. When the screw dislocations and the pits are observed in the first main surface, a percentage obtained by dividing a number of the pits by a number of the screw dislocations is 1% or less. A concentration of magnesium in the first main surface is less than 1×1011 atoms/cm2.