We propose a new scheme aimed at cooling nanostructures to microkelvin temperature based on the well established technique of adiabatic nuclear demagnetization: we attach each device measurement lead to an individual nuclear refrigerator, allowing efficient thermal contact to a microkelvin bath. On a prototype consisting of a parallel network of nuclear refrigerators, temperatures of ∼1 mK simultaneously on ten measurement leads have been reached upon demagnetization, thus completing the first steps toward ultracold nanostructures.

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Abstract-The susceptibility of single-crystal silicon and SU-8 resonators to proton-radiation induced degradation was investigated. Both materials are in widespread use for microsystems structures, thus the stability of the mechanical properties must be ensured over the full device lifecycle. Effects of spacerelevant proton doses were examined by monitoring minute changes in the Young's modulus and by structural investigations using high-resolution X-ray diffraction (HRXRD). Single crystal silicon resonators were exposed to 10 MeV and 60 MeV protons with doses up to 10 13 cm −2 . Even at the highest doses neither a change of the Young's modulus was observed nor did Xray diffraction indicate the formation of elevated concentrations of structural defects. The compatibility of SU-8 with inorbit radiation environments was investigated at fluences of 10 10 -10 12 cm −2 using protons with energies ranging from 10 MeV to 200 MeV. Its elastic modulus changed by less than 5.5% at the highest doses.[2013-0009]

Imperfections, like surface roughness and defects, introduced by common manufacturing processes are recognized to favor failure of microfabricated components and systems. Up to now only a reduced part of the ideal strength prediction by zero Kelvin quantum mechanical ab initio calculations could be recovered for micrometer‐sized structures manufactured with DRIE. Within the present work the high‐loading fracture behavior of group IV semiconductors is investigated on the basis of specific DRIE‐etched micrometer‐sized single crystal silicon (SCSI) specimens. Aiming an enhancement of the surface quality, the samples are post‐treated using wet etchants, such as KOH and HNA and oxidation processes, such as thermal and hydrogen oxidation. The resistance of the specimens against mechanical loading is assessed by 2‐point bending tests applying a testing procedure which is outstanding due to its simplicity in handling and reproducibility of the measurement results. The experiments are analyzed and evaluated for Young's modulus, fracture and bending strength. Dependent on the particular treatment method, remarkable improvements of fracture strain and stress of up to ϵmax = 5.7% and σmax = 8.8 GPa are realized.

This work reports on irradiations made on silicon bulk-acoustic wave resonators. The resonators were based on a tuning fork geometry and actuated by a piezoelectric aluminum nitride layer. They had a resonance frequency of 150 kHz and a quality factor of about 20000 under vacuum. The susceptibility of the devices to radiation induced degradation was investigated using 60 Co γ-rays and 50 MeV protons with space-relevant doses of up to 170 krad. The performance of the devices after irradiation indicated a high tolerance to both ionizing damage and displacement damage effects. The results support the efforts towards design and fabrication of highly reliable MEMS devices for space applications.

We report on the susceptibility of structural MEMS materials to proton radiation damage. Radiation tests at spacerelevant doses were conducted on MEMS resonators. The two materials examined were single crystal silicon and SU-8, which are both in widespread use in microsystems. The resonance frequency was monitored for measuring minute changes of the Young's modulus. No radiation-induced changes of the elasticity were observed in the silicon devices up to fluences of 10 13 cm-2 , corresponding to a total ionizing dose (TID) of over 5.5 MRad for 10 MeV protons. The SU-8 resonators showed a variation of less than ±5.5% at doses of up to 1.4 Mrad (TID). Chemical and structural analyses of the polymer were performed using infrared absorption spectroscopy and x-ray diffraction methods. We discuss possible mechanisms for the observed changes of the elasticity of SU-8.

This work reports on mechanical tests and irradiations made on silicon bulk-acoustic wave resonators. The resonators were based on a tuning fork geometry and actuated by a piezoelectric aluminum nitride layer. They had a resonance frequency of 150 kHz and a quality factor of about 20,000 under vacuum. The susceptibility of the devices to radiation-induced degradation was investigated using 60 Co γ-rays and 50 MeV protons with space-relevant doses of up to 170 krad. The performance of the devices after irradiation indicated a high tolerance to both ionizing damage and displacement damage effects. In addition, the device characteristics were evaluated after mechanical shock and vibration tests and only small effects on the devices were observed. In all experiments, no significant changes of the resonance characteristics were observed within the experimental uncertainty, which was below 100 ppm for the resonance frequency. The results support the efforts toward design and fabrication of highly reliable MEMS devices for space applications. Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms

The mechanical stability of silicon MEMS dies is strongly influenced by the microfabrication processes, especially grinding, dicing and etching, which leave characteristic damage (defects, cracks, dislocations…) in the substrate material. Specially designed mechanical tests are used to assess the resistance of micro-structures to monotonic and cyclic loading. We report on the development progress of a micromechanical test bench for reliability assessment of microstructures in 2-, 3-and 4-point bending configurations. Strain distributions and defects in micron-sized silicon devices can be investigated by in-situ testing in combination with high-resolution x-ray diffraction measurements for experimentally assessing the strain distribution.