SiC Epitaxial Substrate Mounting Member Curvature Control
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Solution Overview
Problem
During epitaxial growth on SiC substrates, the adhesion of SiC sublimates to the back surface causes protrusions, leading to non-uniform temperature distribution and reduced yield due to the curvature of supporting plates in existing configurations, which complicates the process and increases costs.
Innovation Solution
A substrate mounting member with a SiC-coated wafer plate and a non-SiC-coated supporting plate, where the supporting plate's thickness is optimized to suppress curvature and maintain uniform temperature distribution by ensuring the SiC sublimates adhere to the supporting plate rather than the SiC substrate, and the supporting plate is either flat or spaced apart from the SiC substrate to prevent contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a SiC-coated wafer plate is used as a substrate mounting member, then SiC sublimation occurs at epitaxial growth temperature, but SiC sublimates adhere to the back surface of the SiC substrate causing protrusions that deteriorate flatness
Solution Approach 1:
A supporting plate is introduced as an intermediary component between the SiC-coated wafer plate and the SiC substrate. This supporting plate serves as a mediator that receives SiC sublimates instead of allowing them to adhere directly to the substrate back surface, thereby preventing protrusion formation while maintaining the necessary thermal and structural functions.
2Manufacturing precision
If a supporting plate uncoated with SiC is mounted between the SiC substrate and wafer plate, then SiC sublimates adhere to the supporting plate improving substrate flatness, but the supporting plate curvature varies causing non-uniform temperature distribution
Solution Approach 1:
The thickness of the supporting plate is precisely controlled within a specific range (0.5-2.0 mm) to optimize its mechanical and thermal properties. By adjusting this critical parameter, the supporting plate maintains sufficient flatness to ensure uniform temperature distribution across the substrate while still effectively capturing SiC sublimates on its back surface.
3Productivity
If the height difference between substrate and wafer plate is reduced to prevent turbulent gas flow, then gas flow stability improves, but curvature in the supporting plate causes the substrate to come out of the counterbore portion
Solution Approach 1:
The supporting plate is designed with pre-determined thickness and structural characteristics that compensate for potential curvature effects before the epitaxial growth process begins. This preliminary design ensures that even when SiC sublimates are deposited during growth, the substrate remains properly positioned within the counterbore portion throughout the entire growth cycle.
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 configuration effectively suppresses the formation of SiC protrusions on the back surface of the substrate, maintains uniform in-plane temperature distribution, and enhances the epitaxial growth rate and yield by stabilizing the contact area and preventing sublimates from adhering to the substrate.
Implementation Method 1
the carbon-made susceptor is heated up to an epitaxial growth temperature by induction heating
Implementation Method 2
since SiC coated on the wafer plate is a polycrystal, SiC sublimates at the epitaxial growth temperature
Implementation Method 3
a SiC sublimate is adhered to the back surface of the SiC substrate whose temperature is lower than that of the wafer plate to three-dimensionally grow
Data Source
AI summary
A substrate mounting member according to the present invention is a member for mounting a SiC substrate for epitaxial growth, which includes a wafer plate including a SiC polycrystal, and a supporting plate configured to be placed on the wafer plate, include no SiC polycrystal and have a surface serving as a SiC substrate placing surface, the surface being on the side opposite to a surface in contact with the wafer plate, and in which a thickness h [mm] of the supporting plate satisfies an expression h4≤3 pa4(1−v2){(5+v)/(1+v)}/16E when a force applied to a unit area of the supporting plate by a self-weight of the supporting plate and by the SiC substrate is represented as p [N/mm2], a radius of the supporting plate as a [mm], a Poisson's ratio as v and a Young's modulus as E [MPa].