Sputtered W–N diffusion barriers

Creators: Kattelus, H. P.; Kolawa, E.; Affolter, K.; Nicolet, M.-A.

Abstract

The thermal stability of reactively sputtered tungsten–nitrogen alloy thin films is investigated for the application as diffusion barriers in silicon contact metallizations. The composition of W–N barriers is varied over a wide range including pure W. Aluminum, gold, and silver are used as low resistivity overlayers. Metallurgical interactions at temperatures ranging from 500 to 900 °C are studied. Incorporating nitrogen into tungsten advantageously stabilizes all three systems. The overall failure takes place rapidly above critical temperatures that depend on both the metal overlayer and the microstructure of the barrier. In some cases, W–N alloys can effectively prevent interdiffusion at temperatures as high as 800 °C for 30 min.

Additional Information

© 1985 American Vacuum Society (Received 30 April 1985; accepted 3 June 1985) We thnak J. L. Tandon, Applied Solar Energy Corporation, City of Industry, California, for his help in SEM analysis, A. E. Morgan, Signetics Corp., Sunnyvale, California, for AES analysis, and R. Gorris, Caltech, for technical assistance. We are also indebted to A. A. Jaecklin, Brown Boveri & Cie, Baden, Switzerland, for the gifyt of high purity Si substrates. This work was financially supported in part by the Department of Energy through an agreement with the National Aeronautics and Space Administration and monitored by the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, and by the U.S. Army, Elewctronic Technology and Devices Laboratory (ERADCOM), Ft. Monmouth, New Jersey.

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