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

Jan-Uwe Schmidt; Martin Friedrichs; Andreas Gehner

doi:10.1117/1.2945230

1 April 2008 Amorphous TiAl films for micromirror arrays with stable analog deflection integrated on complementary metal oxide semiconductors

Jan-Uwe Schmidt, Martin Friedrichs, Andreas Gehner

Author Affiliations +

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 7, Issue 2, 021012 (April 2008). https://doi.org/10.1117/1.2945230

Abstract

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.

©(2008) Society of Photo-Optical Instrumentation Engineers (SPIE)

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Jan-Uwe Schmidt, Martin Friedrichs, and Andreas Gehner "Amorphous TiAl films for micromirror arrays with stable analog deflection integrated on complementary metal oxide semiconductors," Journal of Micro/Nanolithography, MEMS, and MOEMS 7(2), 021012 (1 April 2008). https://doi.org/10.1117/1.2945230

Published: 1 April 2008

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