Gold metallizations for eutectic bonding of silicon wafers

Gold eutectic bonding of silicon wafers is a good candidate for wafer level vacuum packaging of vibrating MEMS: in this paper we investigated several e-beam evaporated metallizations stacks including a titanium adhesion layer, an optional diffusion barrier (Ni or Pt) and a gold film for eutectic bonding on Si and SiO₂/Si wafers. Interdiffusion in the multilayers for annealing temperatures (380–430°C) larger than the Au–Si eutectic temperature (363°C) and times corresponding to a bonding process was characterized by RBS, roughness and resistivity measurements. Au/Pt/Ti and Au/Ti/SiO₂ were found to have the best characteristics for bonding. This was confirmed by bonding experiments.     

Characterization of NbSi TES Bolometers: Preliminary Results

We present preliminary results on characterisation of voltage biased superconducting bolometers with an NbSi alloy sensor. I(V) curves as well as complex impedance and noise measurements are carried out in a dilution fridge with a pulse tube as a first stage cooler. SQUIDs polarization and addressing are controlled by a cold ASIC in which a SiGe amplifier has been implemented. First characterisations were done on full membrane bolometers and show a noise level of about $10^{-16}\ \mathrm{W}/\sqrt{\mathrm{Hz}}$ . Those detectors are developed for the QUBIC experiment, a B-modes telescope that will be deployed in Antactica in 2013.     

Latest NIKA Results and the NIKA-2 Project

NIKA (New IRAM KID Arrays) is a dual-band imaging instrument installed at the IRAM (Institut de RadioAstronomie Millimetrique) 30-meter telescope at Pico Veleta (Spain). Two distinct Kinetic Inductance Detectors (KID) focal planes allow the camera to simultaneous image a field-of-view of about 2 arc-min in the bands 125 to 175 GHz (150 GHz) and 200 to 280 GHz (240 GHz). The sensitivity and stability achieved during the last commissioning Run in June 2013 allows opening the instrument to general observers. We report here the latest results, in particular in terms of sensitivity, now comparable to the state-of-the-art Transition Edge Sensors (TES) bolometers, relative and absolute photometry. We describe briefly the next generation NIKA-2 instrument, selected by IRAM to occupy, from 2015, the continuum imager/polarimeter slot at the 30-m telescope.     

备受争议的嘉利伯

与世界上许多其它公司一样,IBM也处在这样的变革之中。在21世纪初的经济丛林中,最有可能灭绝的物种之一,就是那个长牙巨兽:跨国公司。在竞争和全球环境急剧变化的双重作用下,跨国公司被迫迅速进化为一种不同的生命形式。     

A mm-Wave Polarisation Analyser Using LEKIDs: Strategy and Preliminary Numerical Results

The context of this study is the development of polarisation sensitive detectors in view of future Cosmic Microwave Background experiments. Our goal is to demonstrate the possibility to make a mm-wave polarisation analyser at 150 GHz using Lumped Element Kinetic Inductance Detectors (LEKIDs). Although LEKIDs are very attractive for the relative ease of fabrication, they have an intrinsic optical response which is weakly polarisation-senstive, i.e. orthogonal linear polarisations are absorbed with comparable efficiencies (with a separation typically not exceeding few dB). To overcome this difficulty, we achieve a polarised response by means of small ( \(\sim \lambda \times \lambda \) ) superconducting Nb wire-grids. Each grid is deposited on the rear side of the 300 micron Si substrate, on which 20 nm Al resonators are patterned, so that each pixel may in principle respond as an independent polarisation analyser. Simulations show encouraging results, with a deep (-20 dB) rejection of the unwanted polarisation. Although what we present here is not yet a polarimeter, this pilot study allows us to address some relevant questions that may be crucial in view of a full polarimetric architecture development. In particular, our first prototypes will allow to assess the behaviour of small grids, the interaction between adjacent polarised pixels, and to choose the most suitable resonator geometry. What we present here are preliminary design results about devices which are currently being realised, and soon ready for optical response characterisation.     

Gold metallizations for eutectic bonding of silicon wafers

Gold eutectic bonding of silicon wafers is a good candidate for wafer level vacuum packaging of vibrating MEMS: in this paper we investigated several e-beam evaporated metallizations stacks including a titanium adhesion layer, an optional diffusion barrier (Ni or Pt) and a gold film for eutectic bonding on Si and SiO₂/Si wafers. Interdiffusion in the multilayers for annealing temperatures (380–430°C) larger than the Au–Si eutectic temperature (363°C) and times corresponding to a bonding process was characterized by RBS, roughness and resistivity measurements. Au/Pt/Ti and Au/Ti/SiO₂ were found to have the best characteristics for bonding. This was confirmed by bonding experiments.