Surface Characterization of Sputter-Deposited Cu-Ta Alloys by Auger Electron Spectroscopy

概要

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The structure and oxidation properties of a series of RF sputter-deposited Cu-Ta alloys were studied. They were amorphous in the composition range from 42 to 69 at% Ta (high Ta alloys), while those with 16 and 22 at% Ta (low Ta alloys) were composed of both amorphous and fcc crystalline phases. The in-depth profiles of the Cu-Ta alloys exposed to a laboratory air for a few hours were studied by Auger electron spectroscopy (AES) in combination with Ar ion etching. The surface film consists on Cu-Ta alloys of (Cu, Ta)_xO_y(OH)_z type compound where Cu and Ta were enriched on low and high Ta alloys, respectively. The thickness of the surface film deduced from the in-depth profile increased with Ta content for low Ta alloys while the high Ta amorphous alloys had almost the same film thickness as that of the sputter-deposited tantalum. Enrichment of Cu in the metallic state under the surface film was observed on all the alloys, and especially on Cu-43at%Ta alloy. It is concluded that the red coloration of the alloys is caused not by the preferential oxidation of Cu, but by oxidation of Cu diffused to the top-surface. The initial surface film is not protective enough to prevent the outward diffusion of Cu because of low Ta concentration in the alloy.amorphous alloycopper-tantalum alloyAuger electron spectroscopyin-depth profilesurface analysisoxidationsputter deposition
東北大学の論文
1996-03-28