SiC Epitaxial Wafer Triangular Defect Reduction
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Solution Overview
Problem
The manufacturing of SiC epitaxial wafers is hindered by high surface densities of triangular defects caused by particles attached to the substrate and members within the chamber, leading to reduced yield and quality issues in mass production.
Innovation Solution
Maintaining gas circulation during substrate placement in the glove box and regularly replacing shielding plates and ceilings to minimize particle contamination and member deterioration, thereby reducing the surface density of triangular defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas circulation is stopped during substrate placement to prevent particle scattering, then particle contamination is reduced, but manufacturing precision deteriorates due to triangular defects from attached particles
Solution Approach 1:
The patent applies preliminary action by maintaining gas circulation during substrate placement before the epitaxial growth process begins. This proactive approach ensures that particles are continuously removed from the glove box environment before they can attach to the substrate, preventing the formation of triangular defects without interrupting the circulation flow
Solution Approach 2:
The patent utilizes an inert gas atmosphere (nitrogen or rare gas) in the glove box to create a controlled environment during substrate placement. This inert environment prevents particle generation and attachment while maintaining gas circulation, thereby reducing triangular defects without compromising the placement process
2Manufacturing precision
If shielding plates and ceilings are not replaced regularly to maintain device complexity, then manufacturing cost is reduced, but manufacturing precision deteriorates due to member deterioration and particle generation
Solution Approach 1:
The patent applies preliminary action by proactively replacing shielding plates and ceilings before they deteriorate to a point where they generate significant particles. This preventive maintenance approach, combined with regular monitoring of particle density, ensures that members are replaced at optimal intervals to minimize triangular defects while avoiding unnecessary replacements
Solution Approach 2:
The patent implements a feedback mechanism by monitoring particle density in the glove box and using this information to determine when shielding plates and ceilings should be replaced. This data-driven approach optimizes the replacement schedule, balancing manufacturing precision requirements with device complexity and maintenance costs
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 significantly reduces the surface density of triangular defects, improving the yield and quality of SiC epitaxial wafers by controlling particle attachment and member-related defects during the epitaxial growth process.
Implementation Method 1
A SiC epitaxial wafer includes a SiC epitaxial layer which is formed on a SiC substrate having an off angle
Implementation Method 2
growing a SiC epitaxial film serving as an active region of a SiC semiconductor device on a SiC single crystal substrate
Implementation Method 3
Maintaining gas circulation during substrate placement in the glove box
Data Source
AI summary
A SiC epitaxial wafer including: a SiC epitaxial layer that is formed on a SiC substrate having an off angle, wherein the surface density of triangular defects, in which a distance from a starting point to an opposite side in a horizontal direction is equal to or greater than (a thickness of the SiC epitaxial layer/tan(x))×90% and equal to or less than (the thickness of the SiC epitaxial layer/tan(x))×110%, in the SiC epitaxial layer is in the range of 0.05 pieces/cm2 to 0.5 pieces/cm2 (where x indicates the off angle).