Silicon micromirrors and their prospective application in the Next-Generation Space Telescope

Garcia, Ernest J.; Polosky, Marc A.; Sleefe, Gerard E.

doi:10.1117/12.453829

Cited by 3 publications

(3 citation statements)

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“…The current MSA development focuses on refining fabrication and testing techniques on smaller 128 × 64 MSA prototypes before scaling up the design to flight-sized 384 × 175 MSA dice. Materials selection for the MSA design was based upon a series of previously reported micromechanical tests and numerical analysis [6,7]. The 128 × 64 MSA die are fabricated from silicon-on-insulator (SOI) wafers 8 .…”

Section: Microshutter Array Fabricationmentioning

confidence: 99%

Cryogenic characterization and testing of magnetically-actuated microshutter arrays for the James Webb Space Telescope

King

Kletetschka

Jah

et al. 2005

J. Micromech. Microeng.

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Two-dimensional MEMS microshutter arrays (MSA) have been fabricated at the NASA Goddard Space Flight Center (GSFC) for the James Webb Space Telescope (JWST) to enable cryogenic (-35 K) spectrographic astronomy measurements in the nearinfrared region. Functioning as a focal plane object selection device, the MSA is a 2-D programmable aperture mask with fine resolution, high efficiency and high contrast. The MSA are closepacked silicon nitride shutters (cell size of 100 x 200 pm) patterned with a torsion flexure to allow opening to 90 degrees. A layer of magnetic material is deposited onto each shutter to permit magnetic actuation. Two electrodes are deposited, one onto each siiuiier and another onio the support snucmre side-waii, permitting electrostatic latching and 2-D addressing. New techniques were developed to test MSA under mission-similar conditions (8 K 5 T < 300K). The "magnetic rotisserie" has proven to be an excellent tool for rapid characterization of MSA. Tests conducted with the magnetic rotisserie method include accelerated cryogenic lifetesting of unpackaged 128 x 64 MSA and parallel measurement of the magneto-mechanical stiffness of shutters in "pathfinder" test samples containing multiple MSA designs. Lifetest results indicate a logarithmic failure rate out to -10' shutter actuations. These results have increased our understanding of failure mechanisms and provide a means to predict the overall reliability of MSA devices.

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Section: Microshutter Array Fabricationmentioning

confidence: 99%

Cryogenic characterization and testing of magnetically-actuated microshutter arrays for the James Webb Space Telescope

King

Kletetschka

Jah

et al. 2005

J. Micromech. Microeng.

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“…To develop the field selector for the NIRSpec, MEMS technologies are obviously a wise choice. Several MEMS candidates were considered, including the microshutter array technology, and two micromirror array technologies 3,4 . The disadvantage of using a micromirror array as an object selector is that the mirrors are reflective devices, which diffract and scatter light.…”

Section: Introductionmentioning

confidence: 99%

Microshutter array development for the James Webb space telescope

Acuna

Amatucci

et al. 2005

SPIE Proceedings

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Micro Electromechanical System (MEMS) microshutter arrays are being developed at NASA Goddard Space Flight Center for use as a field selector of the Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST). The microshutter arrays are designed for the spontaneous selection of a large number of objects in the sky and the transmission of light to the NIRSpec detector with high contrast. The JWST environment requires cryogenic operation at 35K. Microshutter arrays are fabricated out of silicon-on-insulator (SOI) silicon wafers. Arrays are closepacked silicon nitride membranes with a pixel size of 100x200 m. Individual shutters are patterned with a torsion flexure permitting shutters to open 90 degrees with a minimized mechanical stress concentration. Light shields are processed for blocking light from gaps between shutters and frames. The mechanical shutter arrays are fabricated using MEMS technologies. The processing includes multi-layer metal depositions, the patterning of magnetic stripes and shutter electrodes, a reactive ion etching (RIE) to form shutters out of the nitride membrane, an anisotropic back-etch for wafer thinning, followed by a deep RIE (DRIE) back-etch to form mechanical supporting grids and release shutters from the silicon substrate. An additional metal deposition is used to form back electrodes. Shutters are actuated by a magnetic force and latched using an electrostatic force. Optical tests, addressing tests, and life tests are conducted to evaluate the performance and the reliability of microshutter arrays.

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“…Micromirror array technologies, as developed by GSFC and Sandia National Laboratories, are also candidates for the object selector for the MOS on NGST 2,3 . The disadvantage of using a micromirror array as an object selector is that micromirrors are reflective devices and they diffract and scatter light and therefore provide low contrast.…”

Section: Introductionmentioning

confidence: 99%

<title>Magnetically actuated microshutter arrays</title>

Mott

Aslam²,

Blumenstock³

et al. 2001

SPIE Proceedings

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Two-dimensional microshutter arrays are being developed at NASA Goddard Space Flight Center (GSFC) for the Next Generation Space Telescope (NGST) for use in the near-infrared region. Functioning as focal plane object selection devices, the microshutter arrays are 2-D programmable masks with high efficiency and high contrast. The NGST environment requires cryogenic operation at 45 K. Arrays are close-packed silicon nitride membranes with a unit cell size of 100x100 micrometer. Individual shutters are patterned with a torsion flexure permitting shutters to open 90 degrees with minimized mechanical stress concentration. The mechanical shutter arrays are fabricated with MEMS technologies. The processing includes a RIE front-etch to form shutters out of the nitride membrane, an anisotropic back-etch for wafer thinning, and a deep RIE (DRIE) back-etch down to the nitride shutter membrane to form frames and to relieve the shutters from the silicon substrate. A layer of magnetic material is deposited onto each shutter. Onto the side-wall of the support structure a metal layer is deposited that acts as a vertical hold electrode. Shutters are rotated into the support structure by means of an external magnet that is swept across the shutter array for opening. Addressing is performed through a scheme using row and column address lines on each chip and external addressing electronics.

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Silicon micromirrors and their prospective application in the Next-Generation Space Telescope

Cited by 3 publications

References 0 publications

Cryogenic characterization and testing of magnetically-actuated microshutter arrays for the James Webb Space Telescope

Cryogenic characterization and testing of magnetically-actuated microshutter arrays for the James Webb Space Telescope

Microshutter array development for the James Webb space telescope

<title>Magnetically actuated microshutter arrays</title>

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