12,316 research outputs found
Microelectromechanical Systems (MEMS) Resistive Heaters as Circuit Protection Devices
With increased opportunities for the exploitation (i.e., reverse engineering) of vulnerable electronic components and systems, circuit protection has become a critical issue. Circuit protection techniques are generally software-based and include cryptography (encryption/decryption), obfuscation of codes, and software guards. Examples of hardware-based circuit protection include protective coatings on integrated circuits, trusted foundries, and macro-sized components that self-destruct, thus destroying critical components. This paper is the first to investigate the use of microelectromechanical systems (MEMS) to provide hardware-based protection of critical electronic components to prevent reverse engineering or other exploitation attempts. Specifically, surface-micromachined polycrystalline silicon to be used as meandering resistive heaters were designed analytically and fabricated using a commercially available MEMS prototyping service (i.e., PolyMUMPs), and integrated with representative components potentially at risk for exploitation, in this case pseudomorphic high-electron mobility transistors (pHEMTs). The MEMS heaters were initiated to self-destruct, destroying a critical circuit component and thwart a reverse engineering attempt. Tests revealed reliable self-destruction of the MEMS heaters with approximately 25 V applied, resulting in either complete operational failure or severely altering the pHEMT device physics. The prevalent failure mechanism was metallurgical, in that the material on the surface of the device was changed, and the specific failure mode was the creation of a short-circuit. Another failure mode was degraded device operation due to permanently altered device physics related to either dopant diffusion or ohmic contact degradation. The results, in terms of the failure of a targeted electronic component, demonstrate the utility of using MEMS devices to protect critical components which are otherwise vulnerable to exploitation
A Technical Note on Quantum Dots for Multi-Color Fluorescence in situ Hybridization
Quantum dots (Qdots) are semiconductor nanocrystals, which are photo-stable, show bright fluorescence with narrow, symmetric emission spectra and are available in multiple resolvable colors. We established a FISH protocol for the simultaneous visualization of up to 6 different DNA probes differentially labeled with Qdots and with conventional organic fluorochromes. Using a Leica SP5 laser scanning confocal microscope for image capture, we tested various combinations of hapten-labeled probes detected with streptavidin-Qdot525, sheep anti-digoxigenin-Qdot605, rat anti-dinitrophenyl-Qdot655 and goat anti-mouse-Qdot655, respectively, together with FITC-dUTP-, Cy3-dUTP- and Texas Red-dUTP-labeled probes. We further demonstrate that Qdots are suitable for imaging of FISH probes using 4Pi microscopy, which promises to push the resolution limits of light microscopy to 100 nanometers or less when applying a deconvolution algorithm, but requires the use of highly photo-stable fluors. Copyright (C) 2009 S. Karger AG, Base
Near-field scanning microwave microscope for interline capacitance characterization of nanoelectronics interconnect
We have developed a noncontact method for measurement of the interline
capacitance in Cu/low-k interconnect. It is based on a miniature test vehicle
with net capacitance of a few femto-Farads formed by two 20-\mu m-long parallel
wires (lines) with widths and spacings the same as those of the interconnect
wires of interest. Each line is connected to a small test pad. The vehicle
impedance is measured at 4 GHz by a near-field microwave probe with 10 \mu m
probe size via capacitive coupling of the probe to the vehicle's test pads.
Full 3D finite element modeling at 4 GHz confirms that the microwave radiation
is concentrated between the two wires forming the vehicle. An analytical lumped
element model and a short/open calibration approach have been proposed to
extract the interline capacitance value from the measured data. We have
validated the technique on several test vehicles made with copper and low-k
dielectric on a 300 mm wafer. The vehicles interline spacing ranges from 0.09
to 1 \mu m and a copper line width is 0.15 \mu m. This is the first time a
near-field scanning microwave microscope has been applied to measure the lumped
element impedance of a test vehicle
Solid immersion lens applications for nanophotonic devices
Solid immersion lens (SIL) microscopy combines the advantages of conventional microscopy with those of near-field techniques, and is being increasingly adopted across a diverse range of technologies and applications. A comprehensive overview of the state-of-the-art in this rapidly expanding subject is therefore increasingly relevant. Important benefits are enabled by SIL-focusing, including an improved lateral and axial spatial profiling resolution when a SIL is used in laser-scanning microscopy or excitation, and an improved collection efficiency when a SIL is used in a light-collection mode, for example in fluorescence micro-spectroscopy. These advantages arise from the increase in numerical aperture (NA) that is provided by a SIL. Other SIL-enhanced improvements, for example spherical-aberration-free sub-surface imaging, are a fundamental consequence of the aplanatic imaging condition that results from the spherical geometry of the SIL. Beginning with an introduction to the theory of SIL imaging, the unique properties of SILs are exposed to provide advantages in applications involving the interrogation of photonic and electronic nanostructures. Such applications range from the sub-surface examination of the complex three-dimensional microstructures fabricated in silicon integrated circuits, to quantum photoluminescence and transmission measurements in semiconductor quantum dot nanostructures
Low Power Superconducting Microwave Applications and Microwave Microscopy
We briefly review some non-accelerator high-frequency applications of
superconductors. These include the use of high-Tc superconductors in front-end
band-pass filters in cellular telephone base stations, the High Temperature
Superconductor Space Experiment, and high-speed digital electronics. We also
present an overview of our work on a novel form of near-field scanning
microscopy at microwave frequencies. This form of microscopy can be used to
investigate the microwave properties of metals and dielectrics on length scales
as small as 1 mm. With this microscope we have demonstrated quantitative
imaging of sheet resistance and topography at microwave frequencies. An
examination of the local microwave response of the surface of a heat-treated
bulk Nb sample is also presented.Comment: 11 pages, including 6 figures. Presented at the Eight Workshop on RF
Superconductivity. To appear in Particle Accelerator
Nanoscale Bandgap Tuning across an Inhomogeneous Ferroelectric Interface
We report nanoscale bandgap engineering via a local strain across the
inhomogeneous ferroelectric interface, which is controlled by the
visible-light-excited probe voltage. Switchable photovolatic effects and the
spectral response of the photocurrent were explore to illustrate the reversible
bandgap variation (~0.3eV). This local-strain-engineered bandgap has been
further revealed by in situ probe-voltage-assisted valence electron energy-loss
spectroscopy (EELS). Phase-field simulations and first-principle calculations
were also employed for illustration of the large local strain and the bandgap
variation in ferroelectric perovskite oxides. This reversible bandgap tuning in
complex oxides demonstrates a framework for the understanding of the
opticallyrelated behaviors (photovoltaic, photoemission, and photocatalyst
effects) affected by order parameters such as charge, orbital, and lattice
parameters
Dielectric Breakdown in Chemical Vapor Deposited Hexagonal Boron Nitride
Insulating films are essential in multiple electronic devices because they can provide essential functionalities, such as capacitance effects and electrical fields. Two-dimensional (2D) layered materials have superb electronic, physical, chemical, thermal, and optical properties, and they can be effectively used to provide additional performances, such as flexibility and transparency. 2D layered insulators are called to be essential in future electronic devices, but their reliability, degradation kinetics, and dielectric breakdown (BD) process are still not understood. In this work, the dielectric breakdown process of multilayer hexagonal boron nitride (h-BN) is analyzed on the nanoscale and on the device level, and the experimental results are studied via theoretical models. It is found that under electrical stress, local charge accumulation and charge trapping/detrapping are the onset mechanisms for dielectric BD formation. By means of conductive atomic force microscopy, the BD event was triggered at several locations on the surface of different dielectrics (SiO2, HfO2, Al2O3, multilayer h-BN, and monolayer h-BN); BD-induced hillocks rapidly appeared on the surface of all of them when the BD was reached, except in monolayer h-BN. The high thermal conductivity of h-BN combined with the one-atom-thick nature are genuine factors contributing to heat dissipation at the BD spot, which avoids self-accelerated and thermally driven catastrophic BD. These results point to monolayer h-BN as a sublime dielectric in terms of reliability, which may have important implications in future digital electronic devices.Fil: Jiang, Lanlan. Soochow University; ChinaFil: Shi, Yuanyuan. Soochow University; China. University of Stanford; Estados UnidosFil: Hui, Fei. Soochow University; China. Massachusetts Institute of Technology; Estados UnidosFil: Tang, Kechao. University of Stanford; Estados UnidosFil: Wu, Qian. Soochow University; ChinaFil: Pan, Chengbin. Soochow University; ChinaFil: Jing, Xu. Soochow University; China. University of Texas at Austin; Estados UnidosFil: Uppal, Hasan. University of Manchester; Reino UnidoFil: Palumbo, Félix Roberto Mario. Comisión Nacional de Energía Atómica; Argentina. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lu, Guangyuan. Chinese Academy of Sciences; República de ChinaFil: Wu, Tianru. Chinese Academy of Sciences; República de ChinaFil: Wang, Haomin. Chinese Academy of Sciences; República de ChinaFil: Villena, Marco A.. Soochow University; ChinaFil: Xie, Xiaoming. Chinese Academy of Sciences; República de China. ShanghaiTech University; ChinaFil: McIntyre, Paul C.. University of Stanford; Estados UnidosFil: Lanza, Mario. Soochow University; Chin
Wide-field Magnetic Field and Temperature Imaging using Nanoscale Quantum Sensors
The simultaneous imaging of magnetic fields and temperature (MT) is important
in a range of applications, including studies of carrier transport, solid-state
material dynamics, and semiconductor device characterization. Techniques exist
for separately measuring temperature (e.g., infrared (IR) microscopy,
micro-Raman spectroscopy, and thermo-reflectance microscopy) and magnetic
fields (e.g., scanning probe magnetic force microscopy and superconducting
quantum interference devices). However, these techniques cannot measure
magnetic fields and temperature simultaneously. Here, we use the exceptional
temperature and magnetic field sensitivity of nitrogen vacancy (NV) spins in
conformally-coated nanodiamonds to realize simultaneous wide-field MT imaging.
Our "quantum conformally-attached thermo-magnetic" (Q-CAT) imaging enables (i)
wide-field, high-frame-rate imaging (100 - 1000 Hz); (ii) high sensitivity; and
(iii) compatibility with standard microscopes. We apply this technique to study
the industrially important problem of characterizing multifinger gallium
nitride high-electron-mobility transistors (GaN HEMTs). We spatially and
temporally resolve the electric current distribution and resulting temperature
rise, elucidating functional device behavior at the microscopic level. The
general applicability of Q-CAT imaging serves as an important tool for
understanding complex MT phenomena in material science, device physics, and
related fields
Accurate Modeling of the Effects of Fringing Area Interface Traps on Scanning Capacitance Microscopy Measurement
Scanning capacitance microscopy (SCM) is a dopant profile extraction tool with nanometre spatial resolution. While it is based on the high-frequency MOS capacitor theory, there are crucial second-order effects which make the extraction of dopant profile from SCM data a challenging task. Due to small size of the SCM probe, the trapped charges in the interface traps at the oxide-silicon dioxide interface surrounding the probe significantly affect the measured SCM data through the fringing electric field created by the trapped charges. In this paper, we present numerical simulation results to investigate the nature of SCM dC/dV data in the presence of interface traps. The simulation takes into consideration the traps response to the ac signal used to measure dC/dV as well as the fringing field of the trapped charge surrounding the probe tip. In the study, we present an error estimation of experimental SCM dopant concentration extraction when the interface traps and fringing field are ignored. The trap distribution in a typical SCM sample is also investigated
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