Rare-Earth Ceramic Coating for Corrosion-Resistant Reactor Components
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Solution Overview
Problem
Existing coating methods for semiconductor equipment components, such as PVD, CVD, and thermal plasma spray, fail to provide thick, dense, and crack-free corrosion-resistant layers, leading to particle shedding and mechanical weakness, especially in environments with corrosive gases and strong electric/magnetic fields.
Innovation Solution
A corrosion-resistant component comprising a ceramic insulating substrate with a non-porous layer containing at least 15% rare earth compounds, characterized by microcrack- and fissure-free microstructure, porosity ≤1%, and grain size of 100 nm to 100 μm, adhered with an adhesion strength of at least 20 MPa, and optionally including interposing layers for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick PVD coatings are applied to provide corrosion resistance, then the coating thickness is increased, but the coating develops internal stresses causing spallation and particle shedding
Solution Approach 1:
The patent changes the deposition parameters by controlling oxygen partial pressure (0.1-10 mTorr) and deposition rate (5-50 nm/min) to create a dense, adherent coating structure. This parameter optimization prevents internal stress accumulation that would otherwise cause spallation, allowing thick coatings to maintain both corrosion resistance and adhesion strength.
Solution Approach 2:
The patent creates a composite coating structure with a dense adherent layer containing rare earth compounds (yttrium oxide, yttrium silicate) combined with dielectric materials. This composite approach provides both the corrosion resistance of rare earth compounds and the mechanical adhesion strength of dielectric materials, preventing coating failure.
2Reliability
If CVD is used to produce dense coatings, then the coating density is increased, but the grain size becomes small (less than 100 nm) creating potential for particle shedding
Solution Approach 1:
The patent optimizes deposition parameters including oxygen pressure and deposition rate to control grain growth during coating formation. By maintaining specific parameter ranges, the process produces coatings with grains larger than 100 nm while preserving high density, eliminating the particle shedding problem associated with fine-grained structures.
3Ease of manufacture
If thermal plasma spray is used to apply rare earth coatings, then the coating application is simplified, but the coating porosity remains high (greater than 1%) causing particle shedding
Solution Approach 1:
The patent replaces the thermal plasma spray mechanical process with a chemical vapor deposition process. This substitution allows precise control of coating formation at the molecular level, creating dense, non-porous structures with less than 1% porosity that prevent particle shedding, while maintaining ease of manufacture through a simplified single-step process.
4Reliability
If rare earth compounds are used as insulating materials, then the corrosion resistance is improved, but the mechanical strength decreases
Solution Approach 1:
The patent creates composite coatings combining rare earth compounds (for corrosion resistance) with dielectric materials (for mechanical strength). This composite structure allows the material to simultaneously achieve high corrosion resistance from the rare earth phase and adequate mechanical strength from the dielectric phase, resolving the trade-off between these properties.
Data Source
AI summary
A corrosion-resistant component configured for use with a semiconductor processing reactor, the corrosion-resistant component comprising: a) a ceramic insulating substrate; and, b) a white corrosion-resistant non-porous outer layer associated with the ceramic insulating substrate, the white corrosion-resistant non-porous outer layer having a thickness of at least 50 μm, a porosity of at most 1%, and a composition comprising at least 15% by weight of a rare earth compound based on total weight of the corrosion-resistant non-porous layer; and, c) an L* value of at least 90 as measured on a planar surface of the white corrosion-resistant non-porous outer layer. Methods of making are also disclosed.