| 摘要 |
PURPOSE: To avoid the deterioration of gaskets and the production of contaminant particles by a method, wherein a protective collar is formed so as to protect the gaskets from a corrosive environment and does not contain metallic fillers and contains a thermoplastic material which is more resistant against the corrosive atmosphere than the material of the gaskets. CONSTITUTION: An annular protective collar 64 is composed of a thermoplastic main part 66, which is formed by injection molding or machining of high strength, heat-resistant and corrosion-resistant thermoplastic material and elastomer gaskets 68 and 76. As the elastomer gaskets 68 and 76 are protected from any corrosive gas leaking whatsoever through a gap 78 between the top part of a side wall 12 and a sealing 20 so that any deterioration of the elastomer gaskets 68 and 76 and the production of contaminant particles in an etching chamber can be avoided.
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