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Amorphous W-Zr Films As Diffusion Barriers Between Al And Si

Published online by Cambridge University Press:  26 February 2011

F. C. T. So ,
X.-A. Zhao ,
E. Kolawa ,
J. L. Tandon ,
M. F. Zhu  and
M-A. Nicolet
F. C. T. So
Affiliation:
California Institute of Technology, Pasadena, CA 91125
X.-A. Zhao
Affiliation:
Shanghai Institute of Metallurgy, Academy of Sciences of China, Shanghai, China
E. Kolawa
Affiliation:
California Institute of Technology, Pasadena, CA 91125
J. L. Tandon
Affiliation:
Applied Solar Energy Corporation, City of Industry, CA 91749
M. F. Zhu
Affiliation:
Graduate School, University of Science and Technology of China, Beijing, China
M-A. Nicolet
Affiliation:
California Institute of Technology, Pasadena, CA 91125
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Abstract

Cosputtered W70Zr30 and W40Zr60 films are investigated as diffusion barriers between Al and Si. W-Zr alloys of both compositions were determined by x-ray diffraction to crystallize at 900°C on Al2O3 substrates. On <111>Si the W-Zr alloy reacts with the substrate above 700°C, forming a uniform, polycrystal line layer of W and Zr suicides. Despite the high crystallization temperatures, an Al overlayer interacts with W-Zr and the Si substrate at ∼500°C. MeV He backscattering spectrometry, SEM and EDAX indicate that this reaction is laterally nonuniform with the formation of deep pits penetrating into the Si substrate. We believe this to be a consequence of fractures in the W-Zr layer induced by reaction with Al. Electrical measurements on shallow junction diodes with <Si>/W-Zr/Al contacts show that the device junctions were thermally stable after a 30 min annealing at 450°C but were all shorted after heat treatments at 500°C or above.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 54 , 1985 , 139
Copyright
Copyright © Materials Research Society 1986

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References

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