Multi-Step CVD Cleaning for Graphite Susceptor Durability
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Solution Overview
Problem
Current methods for cleaning CVD reactors, particularly those using Cl2, are inefficient in removing parasitic coatings and carbon residues from graphite parts, which can lead to suboptimal deposition processes and equipment durability issues.
Innovation Solution
A multi-step cleaning process is implemented in a CVD reactor with a graphite susceptor coated in SiC, utilizing sequential injection of halogen-based gases like Cl2 and O2 at controlled temperatures to convert and remove parasitic coatings, followed by a hydrogen bake to ensure thorough cleaning and equipment conditioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Cl2 is used to remove parasitic coatings from graphite parts, then cleaning effectiveness is improved, but the graphite parts suffer from chlorine attack and durability issues
Solution Approach 1:
The patent converts the harmful effect of Cl2 on graphite into a beneficial cleaning mechanism by using SiC-coated graphite parts. The SiC coating resists Cl2 attack while still allowing effective cleaning of parasitic coatings through controlled chemical reactions, thus protecting the graphite substrate from degradation while maintaining cleaning effectiveness.
Solution Approach 2:
The patent applies a SiC coating layer on the graphite part to create a composite structure. This composite material combines the cleaning effectiveness needed for removing parasitic coatings with the chemical resistance required to withstand Cl2 exposure, solving the contradiction between cleaning efficiency and durability.
2Productivity
If multiple cleaning steps are implemented, then removal of parasitic coatings is improved, but process time and complexity increase
Solution Approach 1:
The cleaning process is divided into multiple sequential steps with different purposes: first removing parasitic coatings, then removing carbon residues, and finally conditioning the surface. Each step uses specific gases and parameters optimized for its particular function, improving overall efficiency while managing process time through structured progression.
Solution Approach 2:
The patent implements continuous cleaning action through sequential gas injections and temperature maintenance. The process maintains elevated temperatures and continuous gas flow through multiple steps, ensuring uninterrupted removal of different coating types without idle time, thus improving removal efficiency while optimizing total process duration.
3Manufacturing precision
If carbon residues are present on graphite parts, then deposition quality is affected, but conventional cleaning methods are insufficient
Solution Approach 1:
The patent uses parameter changes in the cleaning process, specifically varying temperature and gas composition, to effectively remove carbon residues. By controlling temperature ranges and gas flow rates during different cleaning phases, the process achieves thorough removal of carbon deposits that conventional methods cannot handle, thereby improving deposition quality.
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 achieves efficient removal of parasitic coatings and carbon residues, enhancing the deposition process and extending the lifespan of graphite components by maintaining their Cl2 resistance, with etching rates of 80±20 μm/h and effective carbon oxide formation.
Implementation Method 1
a halogen or a halogen compound, is fed into the process chamber (2) in a first cleaning step (21)... in which a halogen or a halogen compound is fed into the process chamber (2)
Implementation Method 2
O2 is fed into the process chamber (2) in a second cleaning step (22)... effective carbon oxide formation
Implementation Method 3
the process chamber (2) is heated to a first cleaning temperature (T1)... the process chamber (2) is brought to a second cleaning temperature (T2)
Implementation Method 4
essentially only H2 is fed into the process chamber (2) in a third cleaning step (23)... after the third cleaning step (23), the process chamber (2) is cooled (24)
Data Source
AI summary
A method for depositing layers containing a group five element on a substrate, in which process gas is fed into a process chamber. After depositing the layer, the process chamber is cleaned as follows. The process chamber is heated to a first cleaning temperature. After reaching the first cleaning temperature, a halogen or a halogen compound is fed into the process chamber in a first cleaning step. After the first cleaning step, the process chamber is brought to a second cleaning temperature. After reaching the second cleaning temperature, O2 is fed into the process chamber in a second cleaning step. After the second cleaning step, the process chamber is brought to a third cleaning temperature. After reaching the third cleaning temperature, substantially only H2 is fed into the process chamber in a third cleaning step. After the third cleaning step, the process chamber is cooled.