Pump

Abstract

A vacuum pump having a high corrosion resistance is disclosed. A member constituting the vacuum pump is composed of aluminum or an aluminum alloy, and the surface of the member is subjected to a plasma oxidation treatment such as an oxidation treatment using oxygen radicals, so that a dense and smooth aluminum oxide coating film is formed thereon.

Description

TECHNICAL FIELD [0001] This invention relates to a pump and, in particular, relates to a vacuum pump for use in a vacuum processing system and a manufacturing method thereof. BACKGROUND ART [0002] Generally, vacuum processing systems for use in manufacturing semiconductor devices or the like include a cluster type system and an in-line type system and these systems each comprise a plurality of chambers and a transfer mechanism for transferring processing members (wafers, glass substrates). In these vacuum processing systems, various treatments such as various film formation and etching are applied to a processing member in each chamber in a state lower than the atmospheric pressure (i.e. vacuum state). In this connection, each chamber constituting the vacuum processing system is provided with a plurality of vacuum pumps for evacuating the chamber. Further, it is a recent trend that members or objects to be processed, such as wafers and glass substrates, become large in size and the ...

AI Technical Summary

Benefits of technology

"The present invention provides a vacuum pump that can resist corrosion in a vacuum processing system. The pump is small in size and light in weight. It has a high corrosion resistance against reactive gases or chemical liquids. The pump member is made of aluminum or an aluminum alloy with an oxide coating film formed by a plasma treatment. The oxide coating film is dense, flat, and has almost no voids. The addition of a noble gas like krypton or xenon can further improve the adhesion and reliability of the pump. The aluminum alloy can also contain magnesium, strontium, barium, zirconium, hafnium, or iron to improve mechanical strength. The method of forming the oxide coating film can be a plasma treatment or an oxygen radical oxidation treatment. Overall, this invention provides a vacuum pump with improved corrosion resistance and reliability for use in vacuum processing systems."

Problems solved by technology

As a result, the vacuum processing systems tend to have a heavy weight such that they are too heavy to be transported by normal transportation means.

However, even if the aluminum alloy would be used in a vacuum pump in the plasma processing system, the inner walls of the vacuum pump is corroded by media such as ions and other active species generated upon dissociation of various gases due to a plasma and corrosive gases.

Therefore, the aluminum alloy cannot be used in the plasma processing system.

On the other hand, if the stainless steel would be also used in the vacuum pump made, it is not possible to obtain sufficient corrosion resistance against the media such as the active species.

However, an Al2O3 coating film formed by anodic oxidation is basically a porous film and the surface thereof is also rough.

Therefore, the anodically oxidized Al2O3 coating film is very low in corrosion resistance against a reactive gas or chemical liquid such as, for example, a Cl-based gas, a F-based gas, HCl, H2SO4, or HF.

Under the circumstances, it takes much time to reach a predetermined degree of pressure-reduction when the above-mentioned anodically oxidized aluminum alloy is used in the plasma system.

This is because, since the oxide coating film at the surface of the anodically oxidized aluminum alloy is primarily porous, it takes an unnecessarily long time to evacuate to the predetermined degree of the pressure-reduction due to a problem of outgassing and the presence of the voids formed and remaining in the film.

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