Rare-Earth Plasma Coating Stress Control for Bonding Durability
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Solution Overview
Problem
Existing plasma processing apparatus components face challenges in maintaining high bonding strength to substrates over long periods, especially under repeated temperature fluctuations, due to the presence of pores in high-purity Y2O3 films formed by thermal spraying.
Innovation Solution
A component for a plasma processing apparatus is designed with a substrate coated by a film of an oxide, fluoride, oxyfluoride, or nitride of a rare earth element, where the film has a compressive stress ratio σ22/σ11 of 5 or less, ensuring isotropic shrinkage and expansion, and an arithmetic mean compressive stress of 200 to 1000 MPa.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-purity Y2O3 film is formed by thermal spraying to provide plasma resistance, then plasma resistance is improved, but the film develops pores that reduce bonding strength to the substrate over time
Solution Approach 1:
The patent changes the physical and chemical parameters of the film by controlling the compressive stress ratio (σ22/σ11 ≤ 5) and arithmetic mean compressive stress (200-1000 MPa). This parameter control enables the film to maintain isotropic shrinkage and expansion characteristics, preventing pore formation and delamination while preserving plasma resistance.
Solution Approach 2:
The patent employs a composite structure consisting of a substrate and a rare earth element oxide/nitride film layer with specific stress characteristics. This composite design combines the plasma resistance of the ceramic film with the mechanical strength of the substrate, while the controlled stress state ensures strong interfacial bonding.
2Productivity
If the film undergoes repeated temperature fluctuations during plasma processing, then plasma processing capability is maintained, but thermal stress causes delamination and reduces bonding strength
Solution Approach 1:
The patent addresses thermal expansion effects by controlling the film's compressive stress state and isotropic shrinkage/expansion characteristics. The controlled stress ratio ensures the film can accommodate thermal cycling without generating excessive differential stress that would cause delamination, thereby maintaining bonding durability during repeated plasma processing.
Solution Approach 2:
The patent modifies the stress parameters of the film (compressive stress ratio ≤ 5 and arithmetic mean stress of 200-1000 MPa) to enable the film to withstand thermal cycling during plasma processing. This parameter control prevents thermal stress-induced delamination while maintaining processing capability.
3Reliability
If the film is made harder to resist plasma erosion, then plasma resistance is improved, but the film becomes more prone to microcrack extension and delamination
Solution Approach 1:
The patent optimizes the compressive stress parameters (ratio σ22/σ11 ≤ 5 and arithmetic mean of 200-1000 MPa) to balance hardness and crack resistance. This parameter control allows the film to maintain plasma erosion resistance while preventing microcrack propagation and delamination by ensuring isotropic dimensional stability.
Solution Approach 2:
The patent converts the potentially harmful effect of compressive stress into a beneficial feature by controlling it within specific parameters. The controlled compressive stress state prevents pore formation and microcrack extension, transforming what could be a source of weakness into a mechanism that enhances film integrity and bonding durability.
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 component achieves high reliability and long-term bonding strength to the substrate, reducing particle contamination and microcrack extension, while maintaining hardness and resistance to internal tensile stress.
Implementation Method 1
a ratio σ22/σ11 of a compressive stress σ11 to occur across a surface of the film to be exposed to plasma and a compressive stress σ22 to occur across the surface in a direction perpendicular to the compressive stress σ11 is 5 or less
Implementation Method 2
ensuring isotropic shrinkage and expansion
Implementation Method 3
high strength of bonding to the substrate over a long period of time
Data Source
AI summary
A component for a plasma processing apparatus includes a substrate and a film on at least a part of the substrate. The film includes an oxide, a fluoride, an oxyfluoride, or a nitride of a rare earth element. A ratio σ22/σ11 of a compressive stress σ11 to occur across a surface of the film to be exposed to plasma and a compressive stress σ22 to occur across the surface in a direction perpendicular to the compressive stress σ11 is 5 or less. A plasma processing apparatus includes the above component.