Fraunhofer Institute for Silicon Technology


Fraunhofer Institute for Silicon Technology

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Knieling T.,Fraunhofer Institute for Silicon Technology | Shafi M.,University of Bremen | Lang W.,University of Bremen | Benecke W.,Fraunhofer Institute for Silicon Technology
Journal of the European Optical Society | Year: 2012

The fabrication of arrays consisting of densely ordered circular convex microlenses with diameters of 126 μm made of quartz glass in a photoresist reflow and dry etch structure transition process is demonstrated. The rectangular lens arrays with dimensions of 6 mm × 9 mm were designed for focussing collimated light on the pixel center regions of a translucent interference display, which also was produced in microtechnological process steps. The lenses focus light on pixel centers and thus serve for increasing display brightness and contrast since incoming collimated light is partially blocked by opaque metallic ring contacts at the display pixel edges. The focal lengths of the lenses lie between 0.46 mm and 2.53 mm and were adjusted by varying the ratio of the selective dry etch rate of photoresist and quartz glass. Due to volume shrinking and edge line pinning of the photoresist structures the lenses curvatures emerge hyperbolic, leading to improved focussing performance.

Neumann G.,Fraunhofer Institute for Silicon Technology | Wursig A.,Fraunhofer Institute for Silicon Technology
Physica Status Solidi - Rapid Research Letters | Year: 2010

The Expert Opinion is written by a distinguished scientist and presents his personal view on important and relevant new results of research, highlighting their significance and putting the work into perspective for a broader audience. Please send comments to or to the author. The text by G. Neumann and A. Würsig refers to the Rapid Research Letter by H. Föll et al., published in this issue of Phys. Status Solidi RRL 4, 4-6 (2010). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hofmann U.,Fraunhofer Institute for Silicon Technology | Janes J.,Fraunhofer Institute for Silicon Technology | Quenzer H.-J.,Fraunhofer Institute for Silicon Technology
Micromachines | Year: 2012

This paper reports on design, fabrication and characterization of high-Q MEMS resonators to be used in optical applications like laser displays and LIDAR range sensors. Stacked vertical comb drives for electrostatic actuation of single-axis scanners and biaxial MEMS mirrors were realized in a dual layer polysilicon SOI process. High Q-factors up to 145,000 have been achieved applying wafer level vacuum packaging technology including deposition of titanium thin film getters. The effective reduction of gas damping allows the MEMS actuator to achieve large amplitudes at high oscillation frequencies while driving voltage and power consumption can be minimized. Exemplarily shown is a micro scanner that achieves a total optical scan angle of 86 degrees at a resonant frequency of 30.8 kHz, which fulfills the requirements for HD720 resolution. Furthermore, results of a new wafer based glass-forming technology for fabrication of three dimensionally shaped glass lids with tilted optical windows are presented. © 2012 by the authors.

Gu-Stoppel S.,Fraunhofer Institute for Silicon Technology | Janes J.,Fraunhofer Institute for Silicon Technology | Kaden D.,Fraunhofer Institute for Silicon Technology | Quenzer H.J.,Fraunhofer Institute for Silicon Technology | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

This paper presents design, fabrication and measurements for single-axis piezoelectric MEMS micromirrors with 1 mm2 apertures. These micromirrors, which feature thin-film PZT actuators and mechanical leverage amplification, are dedicated for laser projection and meet the requirements of high resonant frequency and large deflection angles. To identify the optimal micromirror geometries a parametric study by means of FEM simulations and analytic modeling has been performed. Characterization, related to the material qualities of PZT and the mechanical performance of the micromirrors, have verified the reliability of the process, the robustness and the performance of the fabricated prototypes. According to the measurements the fabricated micromirrors feature high Q-factor about 1570. The micromirror reaches the θopt·D product of 42.5 °·mm at 32 kHz driven by a low voltage of 7 V. Furthermore, new designs with larger apertures and deflections are currently being developed. © 2013 Copyright SPIE.

Greve H.,University of Kiel | Woltermann E.,University of Kiel | Quenzer H.-J.,Fraunhofer Institute for Silicon Technology | Wagner B.,Fraunhofer Institute for Silicon Technology | Quandt E.,University of Kiel
Applied Physics Letters | Year: 2010

Thin film magnetoelectric (ME) two-two composites consisting of AlN and amorphous (Fe90 Co10)78 Si12 B 10 layers were fabricated by magnetron sputtering on Si (100) substrates. Upon magnetic field annealing they show an extremely high ME coefficient of 737 V/cm Oe at mechanical resonance at 753 Hz and 3.1 V/cm Oe out of resonance at 100 Hz. These are the highest reported ME coefficients in thin film composites ever. Furthermore, the induced magnetic anisotropy by field annealing serves the possibility to obtain a sensor element with a pronounced sensitivity in only one dimension, which allows the realization of a three-dimensional vector field sensor. © 2010 American Institute of Physics.

Marauska S.,Fraunhofer Institute for Silicon Technology | Claus M.,Fraunhofer Institute for Silicon Technology | Lisec T.,Fraunhofer Institute for Silicon Technology | Wagner B.,Fraunhofer Institute for Silicon Technology
Microsystem Technologies | Year: 2013

This paper presents the development of a low temperature transient liquid phase bonding process for 8″ wafer-level packaging of micro-electro- mechanical systems. Cu/Sn and Au/Sn material systems have been investigated under varying bonding temperatures from 240 to 280 C and different dwell times from 8 to 30 min. The used bond frame had a width of 80 μm and lateral dimensions of 1.5 mm × 1.55 mm. The sealing frame of the cap wafer consisted of Au and Cu, respectively, and Sn. The MEMS wafer only holds the parent metal of Au or Cu. High quality bonds were confirmed by shear tests, cleavage analysis, polished cross-section analysis using optical and electron microscope, energy dispersive X-ray spectroscopy and pressure cocker test. The samples showed high shear strength (>80 MPa), nearly perfect bond regions and no main failure mode in the cleavage analyses. Non-corroded Cu test structures confirmed the hermeticity. © 2012 Springer-Verlag Berlin Heidelberg.

Stoppel F.,Fraunhofer Institute for Silicon Technology | Lisec T.,Fraunhofer Institute for Silicon Technology | Wagner B.,Fraunhofer Institute for Silicon Technology
2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2015 | Year: 2015

In this paper fabrication and first measurement results of ohmic MEMS switches combining piezoelectric and electrostatic actuation are presented. The switches are based on novel design concepts offering very high contact forces at small device size of less than 0.05 mm2. First fabricated devices with different contact gaps have been characterized with respect to switching speed. Depending on the contact gap the switches enable ultra-fast on- and off-switching within 850 ns and 240 ns, respectively. Good agreement between the experimental and theoretical values obtained by FEM has been observed. Beyond that the switches feature very low contact resistances of only 260 mω during on-state. By applying bidirectional actuation utilizing an additional electrostatic electrode the switches are able to overcome sticking caused by contact welding and offer stable switching behavior at very large contact gaps of up to 9 μm. © 2015 IEEE.

Hofmann U.,Fraunhofer Institute for Silicon Technology | Janes J.,Fraunhofer Institute for Silicon Technology
Advanced Microsystems for Automotive Applications 2011: Smart Systems for Electric, Safe and Networked Mobility | Year: 2011

The concept and design of a low cost two-axes MEMS scanning mirror with an aperture size of 7 millimetres for a compact automotive LIDAR sensor is presented. Hermetic vacuum encapsulation and stacked vertical comb drives are the key features to enable a large tilt angle of 15 degrees. A tripod MEMS mirror design provides an advantageous ratio of mirror aperture and chip size and allows circular laser scanning. © Springer-Verlag Berlin Heidelberg 2011.

Giese T.,Fraunhofer Institute for Silicon Technology | Janes J.,Fraunhofer Institute for Silicon Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Electrostatic driven 2D MEMS scanners resonantly oscillate in both axes leading to Lissajous trajectories of a digitally modulated laser beam reflected from the micro mirror. A solid angle of about 0.02 is scanned by a 658nm laser beam with a maximum repetition rate of 350MHz digital pulses. Reflected light is detected by an APD with a bandwidth of 80MHz. The phase difference between the scanned laser light and the light reflected from an obstacle is analyzed by sub-Nyquist sampling. The FPGA-based electronics and software for the evaluation of distance and velocity of objects within the scanning range are presented. Furthermore, the measures to optimize the Lidar accuracy of about 1mm and the dynamic range of up to 2m are examined. First measurements demonstrating the capability of the system and the evaluation algorithms are discussed. © 2015 SPIE.

Marauska S.,Fraunhofer Institute for Silicon Technology | Jahns R.,University of Kiel | Greve H.,University of Kiel | Quandt E.,University of Kiel | And 2 more authors.
Journal of Micromechanics and Microengineering | Year: 2012

For the measurement of biomagnetic signals in the pico- and femtotesla regime superconducting interference devices (SQUIDs) are commonly used. Their major limitation comes from helium cooling which makes these sensors bulky and expensive. We show that MEMS sensors based on magnetoelectric (ME) composites could be capable as a replacement for biomagnetic measurements. Using surface micromachining processes a cantilever beam with a stack composed of SiO 2/Ti/Pt/AlN/Cr/FeCoSiB was fabricated on a 150mm Si (100) wafer. First measurements of a rectangular micro cantilever with a thickness of 4νm and lateral dimensions of 0.2mm×1.12mm showed a giant ME coefficient ME= 1000 (V m 1)/(A m 1) in resonance at 2.4kHz. The resulting static ME coefficient is ME= 14 (V m 1)/(A m 1). In resonance operation a sensitivity of 780V T 1and noise levels as low as 100 pT Hz 1/2have been reached. © 2012 IOP Publishing Ltd.

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