TaC-Coated Graphite Ring for Longer SiC Epitaxy Service Life
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Solution Overview
Problem
Current graphite rings used in silicon carbide epitaxial processes have short replacement and maintenance intervals, leading to high consumption costs and difficulties in controlling doping concentration due to frequent polishing and replacement, which affects the uniformity and efficiency of the epitaxial layer formation.
Innovation Solution
A graphite ring with a TaC layer covering the inner wall and selectively exposing other surfaces, including regions bordering the inner and outer walls, to prevent falling objects and reduce SiC deposition, thereby extending the replacement and maintenance intervals and improving heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a graphite ring is used in the epitaxial process, then the temperature field can be balanced and adjusted to form a uniform epitaxial layer, but the graphite ring has a short replacement interval and maintenance interval resulting in high consumption costs
Solution Approach 1:
The patent applies composite materials by coating the graphite ring with a SiC layer. This composite structure combines the heat dissipation and temperature balancing properties of graphite with the chemical stability and resistance to SiC deposition of the SiC coating layer, thereby extending the replacement interval while maintaining temperature field balance capability
Solution Approach 2:
The patent changes the surface properties of the graphite ring by altering the coating material from traditional TaC to SiC. This parameter change in coating material composition fundamentally modifies the interaction with SiC vapor during epitaxial growth, preventing coating degradation and extending service life
2Manufacturing precision
If the graphite ring is frequently replaced or maintained, then the doping concentration control can be maintained, but the consumption costs increase and process efficiency decreases
Solution Approach 1:
The patent applies preliminary action by pre-coating the graphite ring with SiC layer before the epitaxial process. This preliminary protective measure prevents SiC deposition on the graphite surface during operation, eliminating the need for frequent maintenance and replacement, thereby maintaining continuous production with stable doping concentration control
3Reliability
If a TaC layer covers the inner wall of the graphite matrix, then the falling object generation is suppressed and replacement interval is extended, but the heat dissipation performance may be affected
Solution Approach 1:
The patent changes the coating material from TaC to SiC, which has different thermal properties. The SiC coating layer provides chemical stability and prevents falling object generation while maintaining better thermal conductivity than TaC, thus resolving the contradiction between protection and heat dissipation
Solution Approach 2:
The patent applies local quality by selectively coating only the inner wall surface of the graphite ring with SiC layer, while leaving the outer surface uncoated or with different coating. This localized coating strategy provides protection where needed (inner wall facing SiC vapor) while maintaining heat dissipation capability where it is most important (outer surface and bulk graphite)
Solution Approach 3:
The patent uses composite materials with SiC coating on graphite substrate. This composite structure leverages the high thermal conductivity of graphite for heat dissipation while the SiC coating layer provides chemical stability and prevents falling object generation, achieving both requirements simultaneously
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 proposed graphite ring design achieves longer replacement and maintenance intervals, reduces sudden changes in doping concentration, and enhances heat dissipation performance, resulting in lower consumption costs and improved process control.
Implementation Method 1
The TaC layer covers the inner wall of the matrix. The TaC layer can protect the inner wall of the matrix, to suppress the inner wall of the matrix from generating a falling object
Implementation Method 2
a graphite ring may be used to balance and adjust a temperature field, to form a uniform epitaxial layer on a surface of a substrate
Implementation Method 3
both the substrate and the epitaxial layer are made of a semiconductor material. Silicon carbide (SiC) is a typical semiconductor material
Data Source
Figure 1A~1C
Figure 2~3
Figure 4~6A
AI summary
This application provides a graphite ring, a preparation method for the graphite ring, and an epitaxial device. The graphite ring may include a graphite matrix and a TaC layer. The graphite matrix has an annular structure, and the graphite matrix includes an upper surface, a lower surface, an inner wall of the matrix, and an outer wall of the matrix. The TaC layer covers the inner wall of the matrix. On the graphite matrix, a part or all of a surface other than the inner wall of the matrix is exposed, or a part or all of a surface other than the inner wall of the matrix is covered with a SiC layer. In the graphite ring provided in this application, the TaC layer covers the inner wall of the matrix, and the TaC layer can protect the inner wall of the matrix, to suppress the inner wall of the matrix from generating a falling object, so that the graphite ring has a long replacement interval. The TaC layer can further hinder deposition of SiC, so that the graphite ring has a long maintenance interval. According to the graphite ring provided in this application, on the graphite matrix, the part or all of the surface other than the inner wall of the matrix is exposed or covered with the SiC layer, so that the graphite ring has good heat dissipation performance.