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Multi-object spectroscopy (MOS) is a powerful tool for space and ground-based telescopes for the study of the formation and evolution of galaxies. This technique requires a programmable slit mask for astronomical object selection. We are engaged in a European development of micromirror arrays (MMA) for generating reflective slit masks in future MOS, called MIRA. The 100 x 200 μm2 micromirrors are electrostatically tilted providing a precise angle. The main requirements are cryogenic environment capabilities, precise and uniform tilt angle over the whole device, uniformity of the mirror voltage-tilt hysteresis and a low mirror deformation. A first MMA with single-crystal silicon micromirrors was successfully designed, fabricated and tested. A new generation of micromirror arrays composed of 2048 micromirrors (32 x 64) and modelled for individual addressing were fabricated using fusion and eutectic wafer-level bonding. These micromirrors without coating show a peak-to-valley deformation less than 10 nm, a tilt angle of 24° for an actuation voltage of 130 V. Individual addressing capability of each mirror has been demonstrated using a line-column algorithm based on an optimized voltage-tilt hysteresis. Devices are currently packaged, wire-bonded and integrated to a dedicated electronics to demonstrate the individual actuation of all micromirrors on an array. An operational test of this large array with gold coated mirrors has been done at cryogenic temperature (162 K): the micromirrors were actuated successfully before, during and after the cryogenic experiment. The micromirror surface deformation was measured at cryo and is below 30 nm peak-to-valley.

The purpose of this study was to determine solutions of 3D wafer level assembly for M(O)EMS structures. Validation of the concept will be done by realizing the assembly of a micro mirrors array which is at the present time assembled at chip level with silver glue (assembly and electrical interconnection). The actual bonding surface is around 5x8 μm2 and the release of mirrors is done before assembly. In this study we will first identify a wafer bonding solution that is compatible with the release process and later applying it to the mirror bonding design in order to verify the compatibility. Two bonding processes were identified as good candidate for this application: Au/Si eutectic and Au/Au thermocompression bonding. For the two processes, a preliminary study was realized to determine bonding parameters, design possibility (minimum bonding surface, density, pitch size) and compatibility with release process (SiO2 etching).

Multi-object spectroscopy (MOS) is a powerful tool for space and ground-based telescopes for the study of the formation and evolution of galaxies. This technique requires a programmable slit mask for astronomical object selection. We are engaged in a European development of micromirror arrays (MMA) for generating reflective slit masks in future MOS, called MIRA. MMA with 100 × 200 μm2 single-crystal silicon micromirrors were successfully designed, fabricated and tested. Arrays are composed of 2048 micromirrors (32 x 64) with a peak-to-valley deformation less than 10 nm, a tilt angle of 24° for an actuation voltage of 130 V. The micromirrors were actuated successfully before, during and after cryogenic cooling, down to 162K. The micromirror surface deformation was measured at cryo and is below 30 nm peak-to-valley. These performances demonstrate the ability of such MOEMS device to work as objects selector in future generation of MOS instruments both in ground-based and space telescopes. In order to fill large focal planes (mosaicing of several chips), we are currently developing large micromirror arrays integrated with their electronics.

International audience; A micromirror array composed of 2048 silicon micromirrors measuring 200 x 100 mu m(2) and tilting by 25 degrees was developed as a reconfigurable slit mask for multi-object spectroscopy (MOS) in astronomy. The fill factor, contrast, and mirror deformation at both room and cryogenic temperatures were investigated. Contrast was measured using an optical setup that mimics a MOS instrument, and mirror deformation was characterized using a Twyman-Green interferometer. The results indicate that the array exhibited a fill factor of 82%, a contrast ratio of 1000:1, and surface mirror deformations of 8 nm and 27 nm for mirrors tilted at 298 K and 162 K, respectively. (c) 2013 Optical Society of America

Next generation of multi-object spectrographs (MOS) in astronomy will use MEMS-based programmable slit masks. Large micromirror arrays with 2048 tiltable micromirrors were fabricated using bulk and surface micro-machining, and wafer level bonding for the assembly. Micromirror size is 100μm × 200 μm and they exhibit very good surface flatness. Mirror architecture as well as a large mechanical tilt angle of 25° lead to a high contrast device, in the order of 1000:1, large enough for objects and background rejection in the MOS field of view. Finally, the micromirrors could be successfully actuated before, during and after cryogenic cooling at 162K.

Multi-object spectroscopy (MOS) is a powerful tool for space and ground-based telescopes for the study of the formation and evolution of galaxies. This technique requires a programmable slit mask for astronomical object selection. We are engaged in a European development of micromirror arrays (MMA) for generating reflective slit masks in future MOS, called MIRA. The 100 x 200 mu m(2) micromirrors are electrostatically tilted providing a precise angle. The main requirements are cryogenic environment capabilities, precise and uniform tilt angle over the whole device, uniformity of the mirror voltage-tilt hysteresis and a low mirror deformation. A first M MA with single-crystal silicon micromirrors was successfully designed, fabricated and tested. A new generation of micromirror arrays composed of 2048 micromirrors (32 x 64) and modelled for individual addressing were fabricated using fusion and eutectic wafer-level bonding. These micromirrors without coating show a peak-to-valley deformation less than 10 nm, a tilt angle of 24 degrees for an actuation voltage of 130 V Individual addressing capability of each mirror has been demonstrated using a line-column algorithm based on an optimized voltage-tilt hysteresis. Devices are currently packaged, wire-bonded and integrated to a dedicated electronics to demonstrate the individual actuation of all micromirrors on an array. An operational test of this large array with gold coated mirrors has been done at cryogenic temperature (162 K): the micromirrors were actuated successfully before, during and after the cryogenic experiment. The micromirror surface deformation was measured at cryo and is below 30 nm peak-to-valley.

We have fabricated and characterized fully programmable MEMS diffraction gratings with long, low-stress, low cross-talk and optically flat micro-mirrors, which can be vertically displaced up to 0.7μm.

Multi-object spectroscopy is a powerful tool for space and ground-based telescopes for the study of the formation of galaxies. This technique requires a programmable slit mask for astronomical object selection. We are developing MEMS-based programmable reflective slit masks for multi-object spectroscopy that consist of micromirror arrays on which each micromirror of size 100 x 200 mu m(2) is electrostatically tilted providing a precise angle. The main requirements for these arrays are cryogenic environment capabilities, precise and uniform tilt angle over the whole device, uniformity of the mirror voltage-tilt hysteresis and a low mirror deformation. A first generation of MEMS-based programmable reflective slit masks composed of 5 x 5 micromirrors was tested in cryogenic conditions at 92 K. Then, first prototypes of large arrays were microfabricated and characterized, but the reliability of these arrays had to be improved. To increase the reliability of these devices, a third generation of micromirror arrays composed of 64 x 32 micromirrors is under development. This generation was especially designed for individual actuation of each mirror, applying a line-column algorithm based on the voltage-tilt hysteresis of the actuator. The fabrication process was optimized and is now based on multiple wafer level bonding steps. Microfabricated devices have micromirror with a peak-to-valley deformation less than 3 nm. The mirrors can be tilted at 20 degrees by an actuation voltage lower than 100 V. First experiments showed that our micromirrors are well suited for the line-column addressing of each micromirror.

Next-generation infrared astronomical instrumentation for ground-based and space telescopes requires MOEMS-based programmable slit masks for multi-object spectroscopy. We made a full space evaluation of Texas Instruments DMD chips, including tests at cold temperature and in vacuum, life tests, radiations, and vibrations and shocks. These results do not reveal any show-stopper concerning its ability to meet environmental space requirements. In parallel, a 100×200µm2 micro-mirror array was successfully designed for cryogenic temperature, fabricated and tested at 92K. Large micromirror arrays of 20'000 micromirrors have also been fabricated. These tests demonstrate the full ability of this type of components for space instrumentation.

We are developing MEMS-based programmable reflective slit masks for future generation infrared multi-object spectroscopy (MOS) for space and ground-based telescopes. These devices are composed of monocrystalline silicon micromirrors of size 200 x 100 um(2) which can be tilted by electrostatic actuation yielding a tilt-angle of 20 degrees. An electromechanical clamping mechanism has been demonstrated providing uniform tilt-angle within one arc minute precision over the whole array (5 x 5 micromirrors). Slit masks of different sizes have been produced; the largest one measures 25 x 22 mm(2) and is composed of 20'000 micromirrors. Thanks to the architecture and the fabrication process of these slit masks; the micromirror peak-to-valley deformation (PTV) is uniform over the device and was measured being below 10 nm for uncoated micromirror. A slit mask of size 5 x 5 micromirrors was successfully tested in cryogenic conditions at 92 K; the micromirrors were actuated before, during and after the cryogenic experiment. To achieve for the large arrays a better fabrication yield and a higher reliability, the architecture, the process flow, the assembly and the electronics are being optimized. Optical characterizations as well as experiments of the large devices are underway.

Multi-object spectroscopy (MOS) is a powerful tool for space and ground-based telescopes for studying the formation of galaxies. This technique requires a programmable slit mask for astronomical object selection. A first sample of MEMS-based programmable reflective slit masks with elements of size 200x100 mu m(2) has been successfully tested in cryogenic conditions at 92 K. Devices of larger size were microfabricated, the largest chip measures 25x22 mm(2) and is composed of 200x100 electrostatic actuated micromirrors. These devices are composed of two chips: the electrode chip and the mirror chip, which are processed separately and assembled consecutively. The mirror chip is bonded on top of the electrode chip and microfabricated pillars on the electrode chip provide the necessary spacing between the two parts. A process flow utilizing refilling techniques based on borophosphosilicate glass (BPSG) deposition and reflow was developed. Programmable reflective slit masks based on this fabrication process were microfabricated and characterized. These devices exhibit a micromirror deformation of 11 nm peak-to-valley and an actuation voltage of 145 V for a tilt angle of 9 degrees. Preparation of samples for MOS experiments are underway.

Next-generation infrared astronomical instrumentation for telescopes requires MOEMS-based programmable slit masks for multi-object spectroscopy. A large micromirror array of 20'000 micromirrors has been fabricated for cryogenic environment utilizing a dedicated assembly stage. Preliminary tests demonstrate the functionality of both the assembly system and the device.

In future space missions for Universe and Earth Observation, scientific return could be optimized using MOEMS devices. Micro-mirror arrays are used for designing new generation of instruments, multi-object spectrographs in Universe Observation and programmable wide field spectrographs in Earth Observation. Mock-ups have been designed and built for both applications and they show very promising results.

MEMS-based programmable slit masks are developed for multi-object spectroscopy in astronomy. Devices with 2048 tiltable micromirrors were fabricated using multiple wafer-level bonding and implemented with individual addressing of each element.

MEMS-based programmable slit masks are developed for multi-object spectroscopy in astronomy. Devices with 2048 tiltable micromirrors were fabricated and tested, exhibiting very good surface flatness, high contrast and cryogenic operation ability.

International audience; The design of ultra-low power micro-hotplates on a polyimide (PI) substrate supported by thermal simulations and characterization is presented. By establishing a method for the thermal simulation of very small scale heating elements, the goal of this study was to decrease the power consumption of PI micro-hotplates to a few milliwatts to make them suitable forvery low power applications. To this end, the mean heat transfer coefficients in air of the devices were extracted by finite element analysis combined with very precise thermographicmeasurements. A simulation model was implemented for these hotplates to investigate both the influence of their downscaling and the bulk micromachining of the polyimide substrate to lower their power consumptions. Simulations were in very good agreement with the experimental results. The main parameters influencing significantly the power consumption at such dimensions were identified and guidelines were defined allowing the design of very small (15 × 15 μm) and ultra-low power heating elements (6 mW at 300 ◦C). These very low power heating structures enable the realization of flexible sensors, such as gas, flow or wind sensors, for applications in autonomous wireless sensors networks or RFID applications and make them compatible with large-scale production on foil such as roll-to-roll or printing processes.

Multi-object spectroscopy (MOS) allows measuring infrared spectra of faint astronomical objects that provides information on the evolution of the Universe. MOS requires a slit mask for object selection at the focal plane of the telescope. We are developing MEMS-based programmable reflective slit masks composed of 2048 individually addressable micromirrors. Each micromirror measures 100 x 200 mu m(2) and is electrostatically tilted by a precise angle of at least 20 degrees. The main requirements for these arrays are precise and uniform tilt angle over the whole device, uniformity of the mirror electromechanical behavior, a flat mirror deformation and individual addressing capability of each mirror. This capability of our array is achieved using a line-column algorithm based on an optimized tilt angle/voltage hysteresis of the electrostatic actuator.