Tailored Etch-Profiles of high aspect ratio trenches to prevent voids after refill with LPCVD sirn

A study is performed to obtain insight in etch- profile tailoring of high aspect ratio trenches (2 μm wide and 40 μm deep) to achieve void-free refilling with LPCVD SiRN. The trench profile obtained with Bosch DRIE is the most important factor determining formation of voids. Various Bosch recipes are characterized with respect to profile determining features and its applicability in void-free refilling

Nanometer resolution TEM sample manipulator for rotational and translational positioning

The design and fabrication process for a high performance manipulation stage for nanometer resolution TEM sample positioning over a 20 μm range is presented. A two level, planar stage is moved in three translational and three rotational directions by just two types of actuators; three horizontal and three vertical combdrives. The vertical combdrives are suspended by optimally designed torsion-beams, improving lateral stiffness by at least a factor of 50 compared to rectangular beams, hence minimizing the chance of electrostatic side pull-in

Design and modeling of a precision 6 DOF MEMS-based parallel kinematic TEM sample manipulator

A design for a 6 Degree-of-freedom precision MEMS-based manipulator for a TEM will is presented. The elastic mechanism is designed and modeled with the specific design considerations regarding kinematic constraint design and elastic energy storage. The typical relatively large deformations of elastic hinges in MEMS result in relatively large displacements and large rigid body rotations. For accurate analysis geometrically non-linear elasticity theory has been used. The drive stiffness has great influence on the longitudinal stiffness of leaf-springs. Leaf-springs used at a relatively low drive stiffness, as is usually the case in MEMS, can benefit from reinforcement, but only in certain cases. The stiffness and so the natural frequency decrease due to deflection of elastic elements in a system can be drastic. In the proposed hexapod design the maximum lowest natural frequency shift due to a displacement of 25 μm is only 10

MEMS 6 degrees of freedom parallel micro manipulator for TEM sample manipulation

Up till now MEMS actuators acted either only in-plane or only out-of plane restricting to 3 DOF manipulation. A design for a millimeter-sized manipulator with 6 degrees of freedom to manipulate a micron-sized substrate at nanometer resolution over strokes of 10 microns with a position stability better than 100 pm over a minute is presented as part of the Multi Axis Micro Stage (MAMS) project of IOP precision technology of SenterNovem. A secondary goal of the project is to generate principle solutions for manipulation and sensing in the micro domain. A parallel kinematic manipulator has been designed in MEMS processes to operate in a TEM environment. The parallel kinematics is used to convert in-plane motion to 6 DOF. For large angles the MEMS device is mounted on a second stage, which is designed with assembly like techniques. Currently the MEMS devices are being processed in the MESA+ clean room

MEMS based 6 degrees-of-freedom parallel kinematic precision micro manipulator

A design is presented for a 6 Degree-of-freedom parallel kinematic precision micro manipulator comprising 3 translations of 20 μm stroke, and three small correction rotation strokes of 5°. The elastic deformations of the manipulator have been optimized for minimal elastic energy storage at a large guiding stiffness. The parallel kinematics facilitates 6 electrostatic lateral comb-drive actuators to be made in-plane of the wafer, using a mechanism to direct the motion to out-of-plane to obtain 6 DOF. One single technology can be used to manufacture the actuators and mechanisms. The fabrication involves deep reactive ion etching with a back-etch release process, offering great design freedom, resulting in a compact design

Rotational precision MEMS-based clamping mechanism for stable fixation of elastic mechanisms

Conventional TEM sample manipulators often lack the crucial stability of 0.1 nm/min. A MEMS manipulator attached directly to the TEM pole would greatly increase both thermal and dynamic stability. However a stable E-beam requires no interference of electric or magnetic fields. Therefore the manipulator should be stably fixed without power. To this end a mechanical clamp is presented which clamps one of the actuators of the TEM sample manipulator (Figure 2). The clamp incorporates a relatively large clamp force of 0.5 mN with respect to the device area and is able to maintain the clamp force without external power. In previous work [1] a theoretical basis has been presented of an earlier clamp version. In this paper a rotational clamp which has been made and tested is presented. This clamp design is part of a research project for a 6 Degree of Freedom MEMS TEM sample manipulator. \u

A planar 3 dof sample manipulator for nano-scale characterization

We present the first monolithic manipulator for in-plane positioning in three degrees of freedom (DOF), based on a parallel flexure-mechanism. The manipulator stage is capable of translation in the x- and y-direction (maximum of ±9 μm) as well as rotation about the z-axis (maximum of ±2 degrees). A power-port based model has been developed to give insight in the systems behavior. The effect of anisotropy in the Young’s modulus of single crystalline silicon (SCS) on the flexure stiffness is modeled and matches the real system

Atypical periosteal osteoid osteoma: a case report

Osteoid osteoma is a benign osteoblastic tumor usually seen in adolescent and young males. In the paediatric age group, since the history may be difficult to elicit, there are often problems in early diagnosis. The author reports an unusual presentation of osteoid osteoma in a ten-year-old girl, which could not be diagnosed by conventional X-rays and CT scan

Stress behaviour and physiology of developing Arctic barnacle goslings (<i>Branta leucopsis</i>) is affected by legacy trace contaminants

Natural populations are persistently exposed to environmental pollution, which may adversely impact animal physiology and behaviour and even compromise survival. Responding appropriately to any stressor ultimately might tip the scales for survival, as mistimed behaviour and inadequate physiological responses may be detrimental. Yet effects of legacy contamination on immediate physiological and behavioural stress coping abilities during acute stress are virtually unknown. Here, we assessed these effects in barnacle goslings (Branta leucopsis) at a historical coal mine site in the Arctic. For three weeks we led human-imprinted goslings, collected from nests in unpolluted areas, to feed in an abandoned coal mining area, where they were exposed to trace metals. As control we led their siblings to feed on clean grounds. After submitting both groups to three well-established stress tests (group isolation, individual isolation, on-back restraint), control goslings behaved calmer and excreted lower levels of corticosterone metabolites. Thus, legacy contamination may decisively change stress physiology and behaviour in long-lived vertebrates exposed at a young age.</p

Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius $A$. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio