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Stress-Corrosion Cracking and Blistering of Thin Polycrystalline Silicon Films in Hydrofluoric Acid

Published online by Cambridge University Press:  15 February 2011

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

Thin (0.1 μm) LPCVD polycrystalline silicon (poly-Si) films are shown to exhibit permeability and suffer structural degradation when exposed to concentrated hydrofluoric acid. Analysis by TEM and SEM reveals two attack mechanisms. (1) Poly-Si films deposited onto phosphosilicate glass (PSG) at 605ºC exhibit tensile residual stress and degrade immediately upon exposure to HF, a phenomenon which we attribute to stress-corrosion cracking. Phosphorus from the PSG layer enters the poly-Si during the deposition, resulting in a microstructural gradient which contributes to the cracking mechanism. (2) As-deposited tensile poly-Si films on phosphorus-free LPCVD SiO2 (LTO) and annealed films on LTO and PSG blister at different rates in HF due to penetration at foreign particle inclusion sites and other film defects. Unannealed compressive films deposited at 650ºC onto PSG do not show any evidence of attack.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 308: Symposium M1 – Thin Films: Stresses and Mechanical Properties IV , 1993 , 641
Copyright
Copyright © Materials Research Society 1993

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References

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