14 September 1994 High-coverage barrier-film formation by ionized cluster beam
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Abstract
A simple deposition model of evaporated species into quarter-micron contacts on an 8-inch diameter wafer, considering the scattering by gas molecules, predicted that the narrow angular distribution of evaporated species and deposition under low vacuum pressure are essential conditions for sufficient coverage of the contacts. An ionized cluster beam (ICB) technique satisfies these essential conditions. Furthermore, computer simulation revealed that rotating the wafer and setting the ion sources off-axis of the wafer center are required in order to obtain bottom coverage uniformity within an 8-inch diameter wafer. The bottom coverage of TiN barrier film deposited under a nitrogen pressure of less than 10-2 Pa into contacts with an aspect ratio of 3.5 was improved to about 30% and the bottom coverage uniformity was about +/- 5% within the wafer. The crystal structure of the film formed by ICB was confirmed to be (111) orientation, which is necessary to from a preferentially oriented aluminum layer with a high durability against electromigration on TiN barrier film. The contact resistance and the leakage current of contact with 0.5 micrometers diameter and 1.5 micrometers depth processed by ICB were lower than 50 (Omega) and 10-10 A respectively at the bias voltage of 10 V.
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Hiroyuki Ishii, Yoichi Hashimoto, Hisashi Tsukazaki, Masahiro Hanai, Hiroki Ito, "High-coverage barrier-film formation by ionized cluster beam", Proc. SPIE 2334, Microelectronics Manufacturability, Yield, and Reliability, (14 September 1994); doi: 10.1117/12.186771; https://doi.org/10.1117/12.186771
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