AVS 45th International Symposium
    Manufacturing Science and Technology Group Monday Sessions
       Session MS-MoA

Paper MS-MoA8
Clean Aluminum Oxide Formation on Surface of Aluminum Cylinder in an Ultraclean Gas Sampling System

Monday, November 2, 1998, 4:20 pm, Room 317

Session: Contamination Free Manufacturing
Presenter: Y. Ishihara, NIPPON SANSO Corporation, Japan
Authors: Y. Ishihara, NIPPON SANSO Corporation, Japan
N. Itou, NIPPON SANSO Corporation, Japan
T. Kimijima, NIPPON SANSO Corporation, Japan
T. Hirano, NIPPON SANSO Corporation, Japan
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Because it is difficult to obtain enough space for a gas-analysis system in semiconductor manufacturing lines, gas purity is usually confirmed by an ex-situ analysis of gas sampled inside the gas-sampling cylinder (sampler). In order to analyze a trace impurities, it is necessary to significantly reduce the contaminants generated in sampler and to fabricate a surface and/or material with an extremely low outgassing rate. We have produced a sampler made of pure Al produced during plasma oxidation in 3% O@sub 2@/Ar after the EX process.@footnote 1@ Nevertheless, the H@sub 2@ concentration in N@sub 2@ or Ar sealed at 0.58MPa in the sampler increased from below 1ppb to 8ppb after 168hours. The CO and CO@sub 2@ concentration in O@sub 2@ also increased. Wet cleaning was carried out in the sampler in the plasma oxidation state by DI water for 72hours at a flow rate of 2L/min. After wet cleaning, the sampler was annealed at 423K for 72 hours in N@sub 2@ without exposure to air. We have confirmed that amorphous @gamma@-Al@sub 2@O@sub 3@ film with a thickness over 0.5µm was formed on the inner surface of the sampler using cross-sectional TEM observation. We have observed that the H@sub 2@ concentration in Ar or N@sub 2@ was maintained below 1ppb, the detection limit of the GC, for 168hours. The CO and CO@sub 2@ concentration in O@sub 2@ were also sufficiently low. These results suggest that the amorphous @gamma@-Al@sub 2@O@sub 3@ film formed by a series of treatments as already mentioned function as a gas-barrier film with an anti-catalytic property. @FootnoteText@ @footnote 1@H. Ishimaru, J.Vac.Sci.Tech., A7(3) 2439 (1989)