TaC-Coated Graphite Susceptor for SiC Epitaxy
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Solution Overview
Problem
Conventional susceptors used in SiC semiconductor manufacturing face issues such as sublimation of the SiC film, adhesion of the film to the wafer, variation in Si and C concentrations during epitaxial growth, and generation of particles due to thermal expansion differences, leading to poor quality semiconductor crystals.
Innovation Solution
A susceptor made of graphite covered with a TaC film, where the TaC film thickness is between 10 to 100 μm, is used, allowing for constant Si and C concentrations and preventing particle generation by using a detachable member that reduces thermal expansion issues and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a SiC-covered graphite material is used as a susceptor at high temperatures (1500°C or more), then the susceptor can withstand the epitaxial growth temperature, but the SiC film sublimates and abrades, causing adhesion to the wafer
Solution Approach 1:
The susceptor uses a composite structure with a graphite base material covered by a SiC film, and the graphite portion uses a specific crystal orientation ((100) plane) to reduce SiC film sublimation. This composite approach combines the high temperature resistance of graphite with the protective properties of SiC coating, while the specific crystal orientation minimizes sublimation and prevents adhesion to the wafer.
2Stability of the object's composition
If a TaC-covered graphite material is used as a susceptor, then thermal expansion differences are reduced, but the SiC layer deposited on the TaC film is easily peeled off, generating particles
Solution Approach 1:
The susceptor applies different surface treatments to different regions: the graphite portion has a specific crystal orientation ((100) plane) that provides good adhesion for deposited SiC layers, while the SiC-covered portion maintains thermal expansion stability. This local differentiation ensures that the SiC layer adheres well where needed without causing particle generation.
3Productivity
If a conventional susceptor is used for epitaxial growth, then the process can be completed, but Si and C concentrations in the atmosphere vary, leading to poor crystal quality
Solution Approach 1:
The susceptor controls the release of Si and C atoms by maintaining a stable temperature and using a graphite base material with specific crystal orientation. This parameter control ensures that Si and C concentrations in the atmosphere remain constant during epitaxial growth, enabling high-quality crystal formation while maintaining productivity.
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 enables the production of high-quality SiC semiconductor crystals by maintaining consistent gas concentrations and preventing particle formation, while allowing for easy replacement of susceptor parts to reduce costs and avoid post-treatment grinding of wafers.
Implementation Method 1
the SiC layer deposited thereon will be easily peeled off resulting from a difference in thermal expansion between the SiC layer and the TaC film
Implementation Method 2
If a SiC-covered graphite material is used as a susceptor in this temperature range, a SiC film that is a constituent of the susceptor is sublimated and abraded
Data Source
AI summary
The invention provides a susceptor capable of obtaining high-quality SiC semiconductor crystals by keeping the Si concentration and C concentration around a wafer constant and by preventing the generation of particles. A susceptor of graphite covered with silicon carbide is characterized in that at least one section of a part on which a wafer is placed is tantalum carbide or a graphite material covered with tantalum carbide. The part on which the wafer is placed may be a detachable member. A material around the part on which the wafer is placed may be a detachable graphite material covered with silicon carbide.