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Stress and Microstructure in Lpcvd Polycrystalline Silicon Films: Experimental Results and Closed Form Modeling of Stresses

Published online by Cambridge University Press:  22 February 2011

P. Krulevitch ,
G. C. Johnson  and
R. T. Howe
P. Krulevitch
Affiliation:
Berkeley Sensor & Actuator Center, Department of Mechanical Engineering, and Computer Sciences, University of California, Berkeley, CA 94720
G. C. Johnson
Affiliation:
Berkeley Sensor & Actuator Center, Department of Mechanical Engineering, and Computer Sciences, University of California, Berkeley, CA 94720
R. T. Howe
Affiliation:
Berkeley Sensor & Actuator Center, Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720
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Abstract

Characterization of undoped polycrystalline silicon films indicates that correlations exist between stress and microstructure. Films of thickness between 0.5–3.6 μm were deposited onto SiO2-covered single crystal silicon wafers between 605 and 700°C using low pressure chemical vapor deposition (LPCVD). The average in-plane film stress and the stress gradient through the film thickness were determined from wafer curvature measurements, and film microstructure was studied with cross-sectional TEM. Films deposited near 605°C exhibit overall tensile stresses that result from an amorphous to crystalline phase change. At deposition temperatures exceeding 630°C, a columnar grain structure evolves out of a transition region of small grains at the SiO2 interface. The columnar films are compressive, with the source of compression linked to the region of small grains. Stress is modeled using a closed form solution ihat considers a linearly elastic contracting ellipsoidal inclusion near the surface of a half space. Several applications of the stress model are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 239: Symposium D – Thin Films: Stresses and Mechanical Properties III , 1991 , 13
Copyright
Copyright © Materials Research Society 1992

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References

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