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Proceedings Paper

Comparison between AlN thin films with different crystal orientations for MEMS applications
Author(s): A. Ababneh; G. Marchand; H. Seidel; J. Hernando; J. L. Sánchez-Rojas; Ü. Sökmen; E. Peiner; U. Schmid
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Paper Abstract

Aluminium nitride (AlN) reactively sputter deposited from an aluminium target is an interesting compound material due to its CMOS compatible fabrication process and its piezoelectric properties. The crystal structure obtained during sputtering is a very importance criterion to obtain a good piezoelectric performance. To demonstrate this, we focused our investigations on two types of films. The first type shows a good c- axis orientation with round grain geometry. The second type is (101) oriented having a triangular grain shape. For measuring the out-of-plane displacements for dij determination, a MSV 400 Polytec scanning laser Doppler vibrometer was used. To obtain the piezoelectric constants d33 and d31 a fitting procedure between experimental and theoretical predicted results is used. Effective values for d33 and d31 in c-axis oriented films are about 3.0 pm/V and -1.0 pm/V, respectively. By contrast, films with (101) orientation show a lower effective longitudinal piezoelectric coefficients, consistent with this different orientation. Finally, both types of AlN layers were deposited on 640 μm long micro-cantilevers. The average displacement of the first mode on the vertical axis was about 12 nm for the film with good c -axis orientation and 0.3 nm for that with (101)- orientation when applying the same excitation.

Paper Details

Date Published: 18 May 2009
PDF: 7 pages
Proc. SPIE 7362, Smart Sensors, Actuators, and MEMS IV, 73621N (18 May 2009); doi: 10.1117/12.821858
Show Author Affiliations
A. Ababneh, Saarland Univ. (Germany)
G. Marchand, Saarland Univ. (Germany)
H. Seidel, Saarland Univ. (Germany)
J. Hernando, Univ. de Castilla, La Mancha (Spain)
J. L. Sánchez-Rojas, Univ. de Castilla, La Mancha (Spain)
Ü. Sökmen, Braunschweig Univ. of Technology (Germany)
E. Peiner, Braunschweig Univ. of Technology (Germany)
U. Schmid, Vienna Univ. of Technology (Austria)

Published in SPIE Proceedings Vol. 7362:
Smart Sensors, Actuators, and MEMS IV
Ulrich Schmid, Editor(s)

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