WC-Coated Graphite Heat-Resistant Member
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Solution Overview
Problem
Conventional heat-resistant members, such as TaC-coated graphite members, face challenges with short lifespan due to low emissivity and high coefficient of thermal expansion, making them unsuitable for high-temperature corrosive environments in semiconductor processes.
Innovation Solution
A heat-resistant member composed of an isotropic graphite base with a dense WC layer having a porosity of less than 3%, which provides enhanced corrosion resistance and emissivity within the range of 30-80%, closer to SiC or pBN, reducing thermal stress-induced cracks and improving durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TaC film is applied on graphite base member, then corrosion resistance is improved, but emissivity decreases and thermal stress causes cracking
Solution Approach 1:
The invention uses a composite structure combining graphite base member with TaC film layer. The TaC film provides corrosion resistance while the graphite substrate maintains high emissivity properties, creating a composite material that achieves both protective function and thermal radiation capability.
Solution Approach 2:
The TaC film is applied selectively on the surface of the graphite base member rather than replacing the entire structure. This local application allows the graphite substrate to maintain its high emissivity properties while the TaC film provides corrosion protection where needed.
2Reliability
If TaC film is applied on graphite base member, then corrosion resistance is improved, but thermal expansion difference causes cracking and peeling
Solution Approach 1:
The invention optimizes the thickness and composition parameters of the TaC film layer to reduce thermal expansion difference with the graphite base member. By controlling these parameters, the film maintains good adhesion and prevents cracking under thermal stress conditions.
Solution Approach 2:
The composite structure of graphite base member with TaC film is designed to accommodate thermal expansion differences. The graphite substrate provides high emissivity while the TaC film provides corrosion resistance, with the composite structure managing thermal stress through material property combinations.
3Object-affected harmful factors
If SiC or pBN coating is used, then high emissivity is achieved, but corrosion resistance in high-temperature environment deteriorates
Solution Approach 1:
The invention creates a composite structure where graphite base member provides high emissivity and TaC film provides corrosion resistance. This composite approach allows simultaneous achievement of both high emissivity and corrosion resistance, overcoming the limitations of single-material coatings.
Solution Approach 2:
The TaC film is applied locally on the surface of the graphite base member, allowing the graphite substrate to maintain its high emissivity properties while the TaC film provides corrosion protection. This local application strategy enables the system to achieve both radiation and protection functions.
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 WC-coated graphite member exhibits improved durability and thermal stability, suppressing peeling and defect generation during semiconductor growth, while maintaining emissivity comparable to SiC or pBN, allowing for seamless thermal design replacement.
Implementation Method 1
a film with a single layer or multiple layers formed on the entire or partial surface of the base member. The film includes a dense WC layer with a single layer or multiple layers, and the dense WC layer includes WC as a main component and has a porosity of less than 3%.
Implementation Method 2
The emissivity of the WC layer falls within a range from 30 to 80%, depending on its porosity. It is markedly higher than that of TaC (from 10 to 20%) and is close to that of SiC or pBN (80% or 70%).
Implementation Method 3
heating the molded film to sinter the TaC particles to obtain a sintered film.
Data Source
AI summary
A heat-resistant member includes a base member composed of an isotropic graphite and a film with a single layer or multiple layers formed on the entire or partial surface of the base member. The film includes a dense WC layer with a single layer or multiple layers, and the dense WC layer includes WC as a main component and has a porosity of less than 3%. The film may further include a porous WC layer with a single layer or multiple layers formed on an entire or partial surface of the dense WC layer. In this case, the porous WC layer preferably includes WC as a main component and has a porosity larger than that of the dense WC layer.