Special Section on Silicon-Based MOEMS and Their Applications

Amorphous TiAl films for micromirror arrays with stable analog deflection integrated on complementary metal oxide semiconductors

[+] Author Affiliations
Jan-Uwe Schmidt

Fraunhofer Institute of Photonic Microsystems, Maria-Reiche-Strasse 2, 01109 Dresden, Germany

Martin Friedrichs

Fraunhofer Institute of Photonic Microsystems, Maria-Reiche-Strasse 2, 01109 Dresden, Germany

Andreas Gehner

Fraunhofer Institute of Photonic Microsystems, Maria-Reiche-Strasse 2, 01109 Dresden, Germany

J. Micro/Nanolith. MEMS MOEMS. 7(2), 021012 (June 26, 2008). doi:10.1117/1.2945230
History: Received April 02, 2008; Revised April 29, 2008; Accepted May 05, 2008; Published June 26, 2008
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Large micromechanical mirror arrays (MMA) with analog pixel deflection integrated onto active CMOS address circuitry require both high-quality planar reflective optical surfaces and a stable deflection versus voltage characteristic. However, for implementing a CMOS-compatible surface-micromachining process, certain obstacles such as a restricted thermal budget and a limited selection of suitable materials must be overcome. Amorphous TiAl is presented as a new actuator material for monolithical MEMS integration onto CMOS circuitry. TiAl films may be sputter deposited at room temperature, have an x-ray amorphous structure, and a low stress gradient. The glassy structure and high melting point make TiAl less vulnerable to stress relaxation, which makes TiAl an ideal spring material. One-level actuators with TiAl or Al-TiAl-Al structural layers and two-level actuators with separate TiAl spring and Al-alloy mirror layers were fabricated and tested with respect to their drift stability. The stability of TiAl-based actuators was found to be superior in comparison to one-level Al-alloy actuators. Two-level actuators with TiAl hinges emerge as the most promising design.

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© 2008 Society of Photo-Optical Instrumentation Engineers

Citation

Jan-Uwe Schmidt ; Martin Friedrichs and Andreas Gehner
"Amorphous TiAl films for micromirror arrays with stable analog deflection integrated on complementary metal oxide semiconductors", J. Micro/Nanolith. MEMS MOEMS. 7(2), 021012 (June 26, 2008). ; http://dx.doi.org/10.1117/1.2945230


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