SiC Substrate Surface Treatment via Si Vapor Etching
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Solution Overview
Problem
The existing surface treatment methods for SiC substrates result in latent scratches and step bunching, which degrade the crystal quality and performance of semiconductor devices, particularly power devices, due to surface roughness and imperfections during epitaxial growth.
Innovation Solution
A surface treatment method that controls the etching mode of SiC substrates under Si vapor pressure by adjusting the etching rate and depth, allowing for the selection of whether to generate step bunching or its type, using anisotropic or isotropic etching modes, and optimizing parameters like temperature, off angle, and inert gas pressure to achieve a smooth terrace and remove latent scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical polishing and chemical mechanical polishing are performed to planarize the SiC substrate surface, then surface roughness is reduced, but latent scratches with disordered crystallinity are generated
Solution Approach 1:
The patent replaces mechanical polishing processes with a thermal etching process using Si vapor pressure. By heating the SiC substrate to 1600-2000°C in a Si-containing atmosphere, the surface is planarized through controlled etching without mechanical contact, thereby eliminating latent scratches while achieving the required surface flatness for epitaxial growth
Solution Approach 2:
The patent changes the physical state and chemical environment parameters by introducing Si vapor pressure and controlling temperature at 1600-2000°C. This creates a chemical etching environment where Si atoms deposit on the SiC surface, selectively removing rough areas and planarizing the surface without generating mechanical damage or latent scratches
2Object-generated harmful factors
If the SiC substrate is heated under Si vapor pressure to etch the surface, then latent scratches are removed and surface is planarized, but step bunching is generated on the surface
Solution Approach 1:
The patent dynamically adjusts etching parameters including temperature (1600-2000°C), Si vapor pressure, and etching time to control the etching rate. By optimizing these parameters, the process removes latent scratches while minimizing step bunching formation, achieving a balance between defect removal and surface morphology control
Solution Approach 2:
The patent utilizes parameter changes in temperature and Si vapor pressure to control the etching kinetics. By precisely controlling these parameters, the etching process selectively removes damaged layers while maintaining surface平整度, and the generated step bunching can be controlled to serve as beneficial templates for subsequent epitaxial growth rather than harmful defects
3Ease of manufacture
If latent scratches remain on the SiC substrate surface, then manufacturing process is simpler, but stacking faults are generated during epitaxial growth degrading crystal quality
Solution Approach 1:
The patent applies a preliminary thermal etching treatment before epitaxial growth to remove latent scratches and prepare the substrate surface. This pre-treatment eliminates the source of stacking faults that would occur during subsequent epitaxial growth, ensuring high crystal quality in the final semiconductor device
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 removes latent scratches and controls step bunching, improving the crystal quality and reducing defects in SiC semiconductor elements, leading to enhanced device performance and stability.
Implementation Method 1
a surface treatment method in which a SiC substrate is etched by heating the SiC substrate under Si vapor pressure
Implementation Method 2
the SiC substrate is etched by heating the SiC substrate under Si vapor pressure
Data Source
AI summary
Provided is a surface treatment method for a SiC substrate (40), the method being capable of controlling whether to generate a step bunching or the type of step bunching that is generated. In the surface treatment method in which the surface of the SiC substrate (40) is etched by heating the SiC substrate (40) under Si vapor pressure, an etching mode and an etching depth which are determined at least on the basis of an etching rate, are controlled to etch the SiC substrate (40), so that a surface pattern of the SiC substrate (40) after etching treatment is controlled.