AVS 49th International Symposium
    Microelectromechanical Systems (MEMS) Thursday Sessions
       Session MM-ThA

Invited Paper MM-ThA3
Development of Individually Addressable Micro-Mirror-Array for Space Applications

Thursday, November 7, 2002, 2:40 pm, Room C-210

Session: Fabrication, Integration, and Packaging Techniques for MEMS
Presenter: S.B. Dutta, NASA, Goddard Space Flight Center
Correspondent: Click to Email
MEMS is a strategic technology thrust area for NASA's missions of the 21st century. It will enable development of sensors and actuators for communication, navigation, propulsion and optical subsystems with low mass and power that operate in space environment. Currently, NASA is supporting MEMS technology development for the Next Generation Space Telescope (NGST), successor of the Hubble Space Telescope (HST) to be launched in 2009. NGST would have a Near InfraRed Multi Object Spectrometer (NIRMOS) that would use programmable slits to select multiple stars and galaxies for simultaneous observation. A team at NASA, Goddard Space Flight Center (GSFC), has developed aluminum, bi-state Micro-Mirror-Array (MMA) operating at 30K that could be used as programmable slits, to support science objectives of NGST. MEMS technology permits fabrication of MMA with self-contained actuation mechanism and direct interfaces to digital electronics. 32x32 MMA has been designed and fabricated using standard CMOS and surface micro-machining processes. The unit cell of MMA contains a square mirror on 100µm pitch and tilts by ± 10 °. The MMA are built on top of CMOS driven address and driver circuit for individual addressing and a CMOS compatible MEMS process has been implemented for compact design. The tilting of the mirrors is achieved by electrostatic attraction between two parallel plate aluminum electrodes. A pair of thin aluminum torsion straps is used so that the voltage required for tilting is less than 20V. The array has been tested successfully to operate at room temperature and at 30K for over 10@super 6@ cycles. Operation of mirror elements has been simulated extensively. Experimental data are in good agreement with model predictions. For optimal operation of MMA, different alloy materials were studied for mirror fabrication. Electro-mechanical modeling, material property studies, fabrication, packaging and optical characterization of the MMA will be presented.