Corrosion-resistant aluminum article for semiconductor processing

Abstract

We have discovered that corrosion of an aluminum article (such as a susceptor) exposed to corrosive halogen-containing species within semiconductor processing apparatus can be avoided by fabricating the article from a high purity aluminum-magnesium alloy having an optimum magnesium content. Upon exposure of the article to a halogen-containing species, a protective magnesium halide layer is formed upon or beneath the surface of the article. The protective layer prevents halogens from penetrating to the base aluminum, thereby protecting the article from corrosion and cracking. To protect the magnesium halide layer from abrasion, the article preferably also includes a hard, cohesive coating over the magnesium halide layer. A preferred cohesive coating is aluminum oxide or aluminum nitride. The magnesium content of the aluminum article, to enable formation of a magnesium halide layer, should be in the range of about 0.1% to about 6% by weight, depending on the operational temperature of the article. For temperatures greater than about 250.degree. C., the magnesium content of the aluminum article should range between about 0.1% by weight and about 1.5% by weight of the article. The magnesium may be present throughout the entire article, or at least in a region of the article beneath or at the surface which is to be rendered corrosion-resistant. Although the magnesium can react with chlorine, fluorine, or bromine to form a protective layer of MgCl.sub.2, MgF.sub.2, MgBr.sub.2 or combinations thereof, the most preferred protective layer is one formed of MgF.sub.2. To ensure that the magnesium present in the aluminum article is available for reaction with the halogen to form the protective layer, the magnesium content should exceed the silicon content of the aluminum article by an amount sufficient to ensure formation of the protective layer.