Rare earth fluoride spray powder and rare earth fluoride-sprayed article

Abstract

A powder comprising rare earth element fluoride particles having an aspect ratio of up to 2, an average particle size of 10-100 m, a bulk density of 0.8-1.5 g / cm3, and a carbon content of 0.1-0.5 wt % is amenable to atmospheric plasma spraying. An article obtained by spraying the rare earth fluoride spray powder to a substrate undergoes few partial color changes and performs well even when used in a halogen gas plasma.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2011-246164 filed in Japan on Nov. 10, 2011, the entire contents of which are hereby incorporated by reference.TECHNICAL FIELD[0002]This invention relates to a rare earth element fluoride thermal spray powder, especially suited for use to form a sprayed coating having corrosion resistance in a halogen-based corrosive gas plasma atmosphere as encountered in the semiconductor device fabrication process, and a rare earth element fluoride-sprayed article.BACKGROUND ART[0003]In the prior art, sprayed coatings having corrosion resistance are used for protecting substrates in a variety of service environments. While aluminum, chromium and similar metal oxides are often used as the thermal spray material, these spray materials are inadequate for use in the semiconductor fabrication process which may include exposure to hot plasma, corrosive attacks, ...

AI Technical Summary

Benefits of technology

The invention is a rare earth element fluoride spray powder that can be used in plasma spraying. The powder has smooth flow and is not decomposed by plasma spraying. The particles are almost spherical and have an aspect ratio of up to 2, with an average particle size of 10 to 100 m. The powder has a bulk density of 0.8 to 1.5 g / cm3, and is made of rare earth elements like yttrium, cerium, and ytterbium or a mixture of these. The powder is solid and stable during handling, with no voids that could trap gas components. The technical effects of the invention include a stable and high-quality rare earth element fluoride spray coating that can be obtained using plasma spraying.

Problems solved by technology

While aluminum, chromium and similar metal oxides are often used as the thermal spray material, these spray materials are inadequate for use in the semiconductor fabrication process which may include exposure to hot plasma, corrosive attacks, and in particular, treatment in a halogen-based corrosive gas plasma atmosphere.

On the other hand, the rare earth fluoride sprayed coatings suffer from a technical problem despite good corrosion resistance.

The plasma spraying of rare earth fluoride has the problem that when the rare earth fluoride is passed through a flame at 3,000° C. or higher for melting, the fluoride can be decomposed so that the material partially converts to a mixture of rare earth fluoride and rare earth oxide.