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

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

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

A Review of Modern Characterization Methods for Semiconductor Materials

The manufacture of solid state devices in the microelectronics industry involves crystal growth, slice preparation, diffusion and implantation, oxide and metal deposition, patterning and etching, probe testing and packaging of completed devices. This simplified process flow is adopted in an overview to briefly outline some established as well as newly developed techniques of materials characterization. The complexity of semiconductor processing has imposed greater stringency criteria which have resulted in the revitalization of old methods as well as the development of new techniques capable of extreme sensitivity and spatial resolution. Examples given for trace impurity and dopant detection include neutron activation analysis, infrared and photoluminescence spectroscopies, atomic resonance ionization, and accelerator based mass spectroscopy. Some methods highlighted for measuring thin film composition and quality are scanning Lang and double crystal x-ray topographies and Rutherford backscattering and Auger spectroscopies. The strengths and frequency of use of these are compared relative to one another and the process steps used in semiconductor manufacture

X-ray ptychography on low-dimensional hard-condensed matter materials

Tailoring structural, chemical, and electronic (dis-)order in heterogeneous media is one of the transformative opportunities to enable new functionalities and sciences in energy and quantum materials. This endeavor requires elemental, chemical, and magnetic sensitivities at the nano/atomic scale in two- and three-dimensional space. Soft X-ray radiation and hard X-ray radiation provided by synchrotron facilities have emerged as standard characterization probes owing to their inherent element-specificity and high intensity. One of the most promising methods in view of sensitivity and spatial resolution is coherent diffraction imaging, namely, X-ray ptychography, which is envisioned to take on the dominance of electron imaging techniques offering with atomic resolution in the age of diffraction limited light sources. In this review, we discuss the current research examples of far-field diffraction-based X-ray ptychography on two-dimensional and three-dimensional semiconductors, ferroelectrics, and ferromagnets and their blooming future as a mainstream tool for materials sciences

Ultra-high-resolution optical imaging for silicon integrated-circuit inspection

This thesis concerns the development of novel resolution-enhancing optical techniques for the purposes of non-destructive sub-surface semiconductor integrated-circuit (IC) inspection. This was achieved by utilising solid immersion lens (SIL) technology, polarisation-dependent imaging, pupil-function engineering and optical coherence tomography (OCT). A SIL-enhanced two-photon optical beam induced current (TOBIC) microscope was constructed for the acquisition of ultra-high-resolution two- and three-dimensional images of a silicon flip-chip using a 1.55μm modelocked Er:fibre laser. This technology provided diffraction-limited lateral and axial resolutions of 166nm and 100nm, respectively - an order of magnitude improvement over previous TOBIC imaging work. The ultra-high numerical aperture (NA) provided by SIL-imaging in silicon (NA=3.5) was used to show, for the first time, the presence of polarisation-dependent vectorialfield effects in an image. These effects were modelled using vector diffraction theory to confirm the increasing ellipticity of the focal-plane energy density distribution as the NA of the system approaches unity. An unprecedented resolution performance ranging from 240nm to ~100nm was obtained, depending of the state of polarisation used. The resolution-enhancing effects of pupil-function engineering were investigated and implemented into a nonlinear polarisation-dependent SIL-enhanced laser microscope to demonstrate a minimum resolution performance of 70nm in a silicon flip-chip. The performance of the annular apertures used in this work was modelled using vectorial diffraction theory to interpret the experimentally-obtained images. The development of an ultra-high-resolution high-dynamic-range OCT system is reported which utilised a broadband supercontinuum source and a balanced-detection scheme in a time-domain Michelson interferometer to achieve an axial resolution of 2.5μm (in air). The examination of silicon ICs demonstrated both a unique substrate profiling and novel inspection technology for circuit navigation and characterisation. In addition, the application of OCT to the investigation of artwork samples and contemporary banknotes is demonstrated for the purposes of art conservation and counterfeit prevention

Industrial Problem Solving with Microbeam Analysis

The objective of this paper is to provide an overview of the microbeam analytical techniques and to help select the appropriate one to solve complex problems often arising in today\u27s high - tech industries. case histories are given to show how renowned analytical service laboratories and microbeam experts formulated their strategies to approach a real life problem, what type of conclusions were deduced from the data and, finally, how the problem was solved

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