Single-crystal silicon is being increasingly employed in a variety of new commercial products not because of its well-established electronic properties, but rather because of its excellent mechanical properties. In addition, recent trends in the engineering literature indicate a growing interest in the use of silicon as a mechanical material with the ultimate goal of developing a broad range of inexpensive, batch-fabricated, high-performance sensors and transducers which are easily interfaced with the rapidly proliferating microprocessor. This review describes the advantages of employing silicon as a mechanical material, the relevant mechanical characteristics of silicon, and the processing techniques which are specific to micromechanical structures. Finally, the potentials of this new technology are illustrated by numerous detailed examples from the literature. It is clear that silicon will continue to be aggressively exploited in a wide variety of mechanical applications complementary to its traditional role as an electronic material. Furthermore, these multidisciplinary uses of silicon will significantly alter the way we think about all types of miniature mechanical devices and components.

Silicon as a mechanical material

Recent developments concerning the rapid single-flux-quantum (RSFQ) circuit family are reviewed. Elementary cells in this circuit family can generate, pass, memorize, and reproduce picosecond voltage pulses with a nominally quantized area corresponding to transfer of a single magnetic flux quantum across a Josephson junction. Functionally, each cell can be viewed as a combination of a logic gate and an output latch (register) controlled by clock pulses, which are physically similar to the signal pulses. Hand-shaking style of local exchange by the clock pulses enables one to increase complexity of the LSI RSFQ systems without loss of operating speed. The simplest components of the RSFQ circuitry have been experimentally tested at clock frequencies exceeding 100 GHz, and an increase of the speed beyond 300 GHz is expected as a result of using an up-to-date fabrication technology. This review includes a discussion of possible future developments and applications of this novel, ultrafast digital technology. >

RSFQ logic/memory family: a new Josephson-junction technology for sub-terahertz-clock-frequency digital systems

This review provides a theoretical basis for understanding the current-phase relation (CPhiR) for the stationary (dc) Josephson effect in various types of superconducting junctions The authors summarize recent theoretical developments with an emphasis on the fundamental physical mechanisms of the deviations of the CPhiR from the standard sinusoidal form A new experimental tool for measuring the CPhiR is described and its practical applications are discussed The method allows one to measure the electrical currents in Josephson junctions with a small coupling energy as compared to the thermal energy A number of examples illustrate the importance of the CPhiR measurements for both fundamental physics and applications

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The current-phase relation in Josephson junctions

The etch rates for 317 combinations of 16 materials (single-crystal silicon, doped, and undoped polysilicon, several types of silicon dioxide, stoichiometric and silicon-rich silicon nitride, aluminum, tungsten, titanium, Ti/W alloy, and two brands of positive photoresist) used in the fabrication of microelectromechanical systems and integrated circuits in 28 wet, plasma, and plasmaless-gas-phase etches (several HF solutions, H/sub 3/PO/sub 4/, HNO/sub 3/+H/sub 2/O+NH/sub 4/F, KOH, Type A aluminum etchant, H/sub 2/O+H/sub 2/O/sub 2/+HF, H/sub 2/O/sub 2/, piranha, acetone, HF vapor, XeF/sub 2/, and various combinations of SF/sub 6/, CF/sub 4/, CHF/sub 3/, Cl/sub 2/, O/sub 2/, N/sub 2/, and He in plasmas) were measured and are tabulated. Etch preparation, use, and chemical reactions (from the technical literature) are given. Sample preparation and MEMS applications are described for the materials.

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Etch rates for micromachining processing

Preface. 1. Normal Metals and the Transition to the Superconducting State. Introduction. Independent Electrons in a Periodic Lattice. Energy Distribution and the Fermi Surface. Free-Electron Gas. Excitations: The Energy Gap in a Superconductor. Electronic Heat Capacity. The Phonon Spectrum. Scattering of Electrons by Phonons. Electrical Conductivity and Resistivity: The Superconducting State. Perfect Conductor vs. Superconductor: The Meissner Experiment. 2. Microscopic Theory of The Equilibrium Superconducting State and Single-Particle Tunneling. Introduction. Electron Pairing. The Cooper Pair Model. Dielectric Functions and Scattering Amplitudes. Attractive Electron-Electron Interaction. Hamiltonian for the Superconducting Ground State. Superconducting Ground State. Gap Parameter and Condensation Energy at T = 0. Excitations from the Ground State. Occupation Statistics for Pairs and Excitations for T ...OE 0. Temperature Dependence of the Gap Parameter. Density of Excitation States. Tunneling Barriers. Tunneling Between Normal Metals. Tunneling Between a Normal Metal and a Superconductor. Ouasiparticle Tunneling Between Superconductors. 3. Electrodynamics of Superconductors in Weak Magnetic Fields. Introduction. Current-Field Relations. Boson-Gas Model: London Equations. Gauge Transformation. Gauge Selection for Simply Connected Superconductors: The London Gauge. dc Electrodynamic Solutions for Superconductors Having Simple Shapes: The Meissner Effect and Penetration Depth. Two-Dimensional Transition Between a Normal Conductor and a Superconductor. Isolated Current-Carrying Thin Strip Electrostatic Analogy. Inductance of Thin Film Lines. Ouantization of Magnetic Flux in a Superconducting Ring. Nonlocal Field-Current Relation: Pippard Coherence Length. Penetration Depths for Pure and Impure Materials at T = 0. Temperature Dependences of Carrier Densities and Penetration Depths The Two-Fluid Model. Complex Conductivity. Electromagnetic Fields in Conducting Media. Superconducting Transmission Lines. Superconducting Passive Microwave Components. 4. Josephson Junctions. Introduction. Pair Tunneling: The Josephson Relations. Gauge Invariance: Effect of a Magnetic Field. Wave Equation for a Josephson Tunnel Junction. Dependence of Maximum Zero-Voltage Current on Magnetic Field. Self-Field Effects: Dependence of I c on Shape and Size of Junction. Resonances in Josephson Junctions. Fiske Modes. Conducting-Barrier Josephson Junctions. Circuit Models of Josephson Junctions. Static I-V Characteristics with a dc Source. Analogs of Small-Area Josephson Junctions. RF Effects in Josephson Junctions. Fluctuations (Noise) in Josephson Junctions. 5. Electronics Applications. Introduction. Josephson Mixing. Quasiparticle Mixing. Bolometers. Parametric Amplifier. RF Signal Generation. Oscillators Based on Flux Dynamics in Long Junctions. Josephson Volt Standard. One-Junction SQUIDS. Multijunction Interferometers (SQUIDs). dc SQUID Magnetometers. RF SQUID Magnetometers. Components for Digital Circuits. Voltage-State Logic. Single Flux Quantum Devices. Rapid Single Flux Quantum Logic. Digital Interface Circuits. Memories in Josephson and Hybrid Technology. 6. Fundamental Thermodynamic and Magnetic Considerations. Introduction. Fundamental Concepts in Statistical Thermodynamics. Interacting Systems. Helmholtz and Gibbs Free Energies. Magnetization. Demagnetization Factors. Energy in Magnetic Fields. Thermodynamic Relations for Magnetic Systems. Phase Transitions. The Superconducting-Normal Phase Transformation. 7. Spatially Dependent Behavior in Superconductors: The Ginzburg-Landau Equations and Departures from the Eissner State. Introduction. Ginzburg-Landau Free-Energy Functional. Ginzburg-Landau Differential Equations. Examples of Solutions of the Ginzburg-Landau Equations The Ginzburg-Landau Parameters. Gor'kov's Microscopic Justification for the Ginzburg Landau Theory. Surface Energy at the Boundary Between Normal and Superconducting Phases in a Homogeneous Medium. Intrinsic Magnetic Behavior of Superconductors. Geometrical Effects: The Intermediate State. Proximity Effects: Contiguous Normal and Superconductive Materials. 8. Type II Superconductivity: Theory and Technology. Introduction. Mixed State in Type II Superconductors: the Vortex Lattice. Londel Model of the Mixed State. Behavior Near H c, Magnetic Flux Configuration in the Mixed State: the Vortex Lattice. Behavior Near H c2 and Surface Conductivity in LTS Materials. Flux Penetration in Thin LTS Films: Critical Fields. Vortex Motion and Flux-Flow Resistance. Thermally Active Flux Motion: Flux Creep and Flux Jumps. The Critical-State Model for Hard Superconductors. The Surface Barrier to Flux Entry in LTS Materials. Stabilization of Superconducting Cables by the Use of Composite Conductors. AC Losses at Power Frequencies. Appendix A: Elements of Electron Tunneling. Appendix B: Determination of Materials from Experimental Data. Appendix C: Computer-Aided-Design Tools.

Principles of Superconductive Devices and Circuits

The relative advantages and disadvantages of three different algorithms are compared for simulating the time evolution of two-dimensional line-edge profiles produced by a locally rate dependent surface etching phenomenon. Simulated profiles typical of optical projection printing and electron-beam and X-ray lithography of micron-sized lines in resist and etching of ion-implanted SiO2 are used as a basis of comparison. One of the algorithms is a cell-by-cell removal model used earlier by Neureuther and Dill. One of the newly developed algorithms employs ray tracing; it can be shown that the path followed by a point on a front between the developed and undeveloped regions can be calculated using ray-optic equations. The other new algorithm uses a string of points initially on the surface of the exposed resist. The points on the string advance perpendicular to the local direction of the string; with time the string of points moves down into the resist, replicating the action of a developer. We compare the computing cost, convenience, and accuracy of the algorithms.

Line‐Profile resist development simulation techniques

A novel asynchronous timing scheme, data-driven self-timing (DDST) is proposed and implemented in Rapid Single-Flux-Quantum (RSFQ) superconductive integrated circuits In this asynchronous approach, the timing signals are generated from the data and no global clock is needed to drive the RSFQ circuit and system The essence of the self-timing scheme is to localize the system timing in order to avoid the overhead of global clock distribution, and to minimize the timing uncertainty The DDST scheme has been applied to the design of a shift register, a demultiplexor, and a self-timed high speed digital test system In this paper, test results of a 4-bit DDST shift register and a high speed on-chip clock generator will be presented to demonstrate the successful DDST operation of RSFQ integrated circuits at a rate of 20 Gb/s

Data-driven self-timed RSFQ digital integrated circuit and system

Josephson junctions are essential components in high‐temperature superconductive integrated circuits. YBaCuO/Nb‐doped SrTiO3/YBaCuO epitaxial Josephson junctions have been designed, fabricated, and tested. The YBaCuO and Nb‐doped SrTiO3 films were deposited by off‐axis sputtering. Both dc and ac Josephson effects have been observed and the supercurrent persists up to 80 K. The critical current density is an exponential function of the barrier layer thickness. The product of critical current and normal resistance is between one and three millivolts. A superconducting quantum interference device made of the junctions displays magnetic field modulation of critical current.

Novel all‐high Tc epitaxial Josephson junction

Discussion sur les mecanismes possibles responsables de la diminution de la vitesse d'attaque avec le dopage. Proposition de reactions d'oxydo-reduction

T. Van Duzer

Papers

Principles of Superconductive Devices and Circuits

Line‐Profile resist development simulation techniques

Data-driven self-timed RSFQ digital integrated circuit and system

Novel all‐high Tc epitaxial Josephson junction

(100) Silicon Etch‐Rate Dependence on Boron Concentration in Ethylenediamine‐Pyrocatechol‐Water Solutions