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Microelectromechanical Systems, Journal of

Issue 4 • Date Dec. 2001

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Displaying Results 1 - 19 of 19
  • Errata to "Self-supporting uncooled infrared microbolometers with low-thermal mass"

    Publication Year: 2001 , Page(s): 616
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  • Author Index

    Publication Year: 2001 , Page(s): 617 - 620
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    Freely Available from IEEE
  • Subject index

    Publication Year: 2001 , Page(s): 620 - 628
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    Freely Available from IEEE
  • An angle-based design approach for rectangular electrostatic torsion actuators

    Publication Year: 2001 , Page(s): 561 - 568
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB) |  | HTML iconHTML  

    In this paper, we develop a fast, angle-based design approach for rectangular electrostatic torsion actuators based on several simple equations. This approach is significantly more straightforward than the usual full calculation or simulation methods. The main results of the simplified approach are verified by comparing them with analytical calculations and MEMCAD simulations with fractional difference smaller than 3% for torsion mode dominant actuators. Also, good agreement is found by comparison with the measured behavior of a microfabricated full-plate device View full abstract»

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  • Microgimbal torsion beam design using open, thin-walled cross sections

    Publication Year: 2001 , Page(s): 550 - 560
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    A thin-film micromolding process enabled the construction of microtorsional springs with unique cross-sectional designs by combining high-aspect-ratio beams with horizontal surface features. Cross sections such as T-bars, pi sections, and channels were utilized in creating torsional springs with low torsional stiffnesses and high in- and out-of-plane bending stiffnesses. Experimental modal analysis was used to determine torsional stiffnesses as low as 0.13 μN·m/deg with T-bar springs 45 μm tall, 50 μm wide, and 100 μm long. Springs of the same outer dimensions but with solid rectangular cross sections were calculated to have torsional stiffnesses of at least two orders of magnitude greater. Several microgimbals were constructed using the thin-film micromolding process with various torsional spring designs. Modal analysis was used to experimentally determine pitch and roll natural frequencies. Torsional stiffness models for open, thin-walled sections that included warping effects were developed and used to analytically predict the torsional natural frequencies of tested spring designs to within 20% View full abstract»

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  • Latching micromagnetic relays

    Publication Year: 2001 , Page(s): 511 - 517
    Cited by:  Papers (49)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB) |  | HTML iconHTML  

    This paper describes the underlying principles, design and operation of a new type of latching micromagnetic relay. The device is based on preferential magnetization of a soft magnetic cantilever in a permanent external magnetic field. Switching between two stable states is accomplished by momentarily changing the direction of the cantilever's magnetization by passing a short current pulse through a planar coil situated under the cantilever. Once the relay is switched, it is held in this nonvolatile state by the permanent external magnetic field. Latching operation has been demonstrated for devices having two different cantilever geometries and a variety of sizes. Characterization has been performed under dc and ac conditions. The minimum (lead-to-lead) resistance through the switch is approximately 50 mΩ.. The switching current and minimum switching pulse width are 79 mA and 0.2 ms, respectively. The operating voltage is about 5 V. The switching energy consumption is <9.3 μJ View full abstract»

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  • Fabrication of ultrathin p++ silicon microstructures using ion implantation and boron etch-stop

    Publication Year: 2001 , Page(s): 532 - 537
    Cited by:  Papers (5)  |  Patents (1)
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    This paper discusses the fabrication of submicron p++ silicon microstructures for a number of MEMS applications using boron ion implantation, rapid thermal annealing, and boron etch-stop. To form these thin structures, the silicon is implanted with boron at an energy of 40 keV and doses of 5×1015 cm-2 and 7×1015 cm-2, which produce a peak concentration of more than 1020 cm-3, sufficient for achieving an effective etch-stop in ethylene diamine pyrocathecol. The thickness of the p++ layer varies from 0.2 to 0.3 μm depending on the annealing time and temperature. SUPREM simulation has been used to determine optimum implantation and annealing conditions. A number of microstructures, including thin silicon diaphragms as large as 2 mm on a side and 0.2 μm thick, hot wire anemometers with a temperature coefficient of resistance of ~1600 ppm/°C, and piezoresistive sound detectors, have been fabricated with high reproducibility, uniformity, and yield View full abstract»

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  • A one-chip scanning retina with an integrated micromechanical scanning actuator

    Publication Year: 2001 , Page(s): 492 - 497
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (139 KB) |  | HTML iconHTML  

    A microsensor that merges sensing and scanning functions on a single chip has been designed and fabricated, resulting in the first integrated scanning retina of its kind. A microfabrication technique has been developed to combine a one-dimensional array of photodiodes and electrostatically driven scanning slits on a single chip. The scanner actuates 12-μm-wide microslits by up to 20 μm on top of 30-μm-wide photodiodes, and the motion generates an effect similar to that of the retinal scanning vergence found in the insects' compound eyes. The silicon retina is coupled with an array of 120-μm-diameter microlenses to compose a microsized scanning compound eye, and the effect of retinal scanning in edge and position detection is demonstrated with the sensor. Each individual visual unit of the compound eye detects light contrast due to the scanning motion of the visual axis. The architecture of this scanning retina increases the resolution of a visual system with a relatively small number of receptors View full abstract»

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  • Manufacturing and packaging of sensors for their integration in a vertical MCM microsystem for biomedical applications

    Publication Year: 2001 , Page(s): 569 - 579
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB) |  | HTML iconHTML  

    Demonstrates the feasibility of integrating fragile micromachined chips into a complex three-dimensional (3-D) multichip module (MCM) microsystem for a biomedical application. The system is based on the vertical integration of the different parts: micropumps and valves, a multisensor chip for on-line control of the system and a signal-processing chip. In this paper, packaging of the microsystem is studied in order to minimize the induced stress that can affect the integrity of the different micromachined parts of the system. Standard commercially available components and materials were used so as to minimize costs for the case of high volume packaging. For testing the approach, a multisensor chip which includes thin silicon membrane-based devices has been used as the main test structure to compare different packaging materials. In addition, for the fabrication of such a sensor chip in an efficient mode, technological modules needed to fabricate sensors on complementary metal-oxide-semiconductor (CMOS) wafers are discussed. The definition of standardized "add-on" sensor modules to the CMOS process of a foundry is intended to limit the development cost of smart sensors View full abstract»

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  • Batch-processed vacuum-sealed capacitive pressure sensors

    Publication Year: 2001 , Page(s): 580 - 588
    Cited by:  Papers (29)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (386 KB) |  | HTML iconHTML  

    This paper reports two multitransducer vacuum-sealed capacitive barometric pressure sensors, one using single-lead and the other using multiple-leads to transfer the electrical signal out of the vacuum-sealed reference cavity. The first device operates with a resolution of 37 mtorr over a pressure range from 600 to 800 torr. The sensitivity is 27 fF/torr (3000 ppm/torr). The TCO at 750 torr is 3900 ppm/°C and the TCS is 1000 ppm/°C. The second device has a resolution of 25 mtorr over a range from 500 to 800 torr, with individual transducer sensitivity of 39 fF/torr. The TCO at 750 torr is 1350 ppm/°C and TCS is 1000 ppm/°C. Both devices have an on-chip compensation capacitor and are read out using an electronically-trimmed switched-capacitor charge integrator View full abstract»

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  • Design and fabrication of submicrometer, single crystal Si accelerometer

    Publication Year: 2001 , Page(s): 518 - 524
    Cited by:  Papers (11)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (182 KB) |  | HTML iconHTML  

    A lateral accelerometer has been designed, simulated, and fabricated using a 3-mask high-aspect ratio technology. Electron beam lithography and high-density plasma etching in an inductively coupled plasma source enabled aspect ratios >30 to be achieved. This makes possible beams with very small spring constants. Combining the ability to measure very small displacement of a proof mass due to narrow capacitive gaps between comb fingers, a highly sensitive accelerometer can be obtained. The fabricated accelerometer with 1 μm beams and 0.2 μm comb gaps had a spring constant of 0.127 N/m, which is close to the calculated values of 0.146 N/m. Based on the capacitance measurements, the accelerometer sensitivity is calculated to be 6.3 fF/g. Reducing the beam width to 0.4 μm lowered the spring constant to 0.03 N/m, and an improved equivalent sensitivity of 79.2 fF/g is calculated. The minimum detectable acceleration is on the order of a few microgravity over a range of hundreds of gravities View full abstract»

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  • A surface-micromachined resonant-beam pressure-sensing structure

    Publication Year: 2001 , Page(s): 498 - 502
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (113 KB) |  | HTML iconHTML  

    The first study on an entirely surface-micromachined resonant-beam pressure sensor is presented. Using a fully surface-micromachined process, an encapsulated beam resonant pressure-sensor structure with a pressure-sensitive diaphragm of 100×150×2 μm has been fabricated. The resonating beam is fully enclosed inside the reference vacuum cavity formed beneath the diaphragm. The new design enables high pressure sensitivity and a miniature chip size, essential for sensors such as catheter-mounted intravascular blood pressure sensors. The pressure sensitivity is measured at 3.2%/bar with a beam resonance frequency of about 700 kHz View full abstract»

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  • Fabrication of multilayer systems combining microfluidic and microoptical elements for fluorescence detection

    Publication Year: 2001 , Page(s): 482 - 491
    Cited by:  Papers (21)  |  Patents (42)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (261 KB) |  | HTML iconHTML  

    This paper presents the fabrication of a microchemical chip for the detection of fluorescence species in microfluidics. The microfluidic network is wet-etched in a Borofloat 33 (Pyrex) glass wafer and sealed by means of a second wafer. Unlike other similar chemical systems, the detection system is realized with the help of microfabrication techniques and directly deposited on both sides of the microchemical chip. The detection system is composed of the combination of refractive microlens arrays and chromium aperture arrays. The microfluidic channels are 60 μm wide and 25 μm deep. The utilization of elliptical microlens arrays to reduce aberration effects and the integration of an intermediate (between the two bonded wafers) aluminum aperture array are also presented. The elliptical microlenses have a major axis of 400 μm and a minor axis of 350 μm. The circular microlens diameters range from 280 to 300 μm. The apertures deposited on the outer chip surfaces are etched in a 3000-Å-thick chromium layer, whereas the intermediate aperture layer is etched in a 1000-Å-thick aluminum layer. The overall thickness of this microchemical system is less than 1.6 mm. The wet-etching process and new bonding procedures are discussed. Moreover, we present the successful detection of a 10-nM Cy5 solution with a signal-to-noise ratio (SNR) of 21 dB by means of this system View full abstract»

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  • Application of a parallel DSMC technique to predict flow characteristics in microfluidic filters

    Publication Year: 2001 , Page(s): 538 - 549
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    Using a parallel implementation of the direct simulation Monte Carlo (DSMC) method, periodic MEMS microfilters are studied in detail. The dependence of the flow characteristics on geometry, Knudsen number, pressure difference, spacing between the filter elements, and accommodation coefficients are investigated. By comparing DSMC results with the widely used analytical formulas, the validity range of the analytical approaches is evaluated. The simulation results show that velocity slip exists both on the filter channel walls and on the filter membrane and results in an increased flow rate. Velocity slip increases strongly with decreasing accommodation coefficients. For long channels, this results in a strong increase in flow rate; whereas for short channels, the increase in flow rate is limited. For the filter separations considered in this paper, we observe that separation between filter channels does not influence the flow rate within each channel View full abstract»

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  • A methodology and model for the pull-in parameters of electrostatic actuators

    Publication Year: 2001 , Page(s): 601 - 615
    Cited by:  Papers (84)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (381 KB) |  | HTML iconHTML  

    This paper presents a generalized model for the pull-in phenomenon in electrostatic actuators with a single input, either charge or voltage. The pull-in phenomenon of a general electrostatic actuator with a single input is represented by an algebraic equation referred to as the pull-in equation. This equation directly yields the pull-in parameters, namely, the pull-in voltage or pull-in charge and the pull-in displacement. The model presented here permits the analysis of a wide range of cases, including nonlinear mechanical effects as well as various nonlinear, nonideal, and parasitic electrical effects. In some of the cases, an analytic solution is derived, which provides physical insight into how the pull-in parameters depend upon the design and properties of the actuator. The pull-in equation can also yield rapid numerical solutions, allowing interactive and optimal design. The model is then utilized to analyze analytically the case of a Duffing spring, previously analyzed numerically by Hung and Senturia, and captures the variations of the pull-in parameters in the continuum between a perfectly linear spring and a cubic spring. Several other case studies are described and analyzed using the pull-in equation, including parallel-plate and tilted-plate (torsion) actuators taking into account the fringing field capacitance, feedback and parasitic capacitance, trapped charges, an external force, and large displacements View full abstract»

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  • Uncooled low-cost thermal imager based on micromachined CMOS integrated sensor array

    Publication Year: 2001 , Page(s): 503 - 510
    Cited by:  Papers (24)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (149 KB) |  | HTML iconHTML  

    We present a micromachined 10×10 array of thermoelectric infrared sensors fabricated in a commercial complementary metal-oxide-semiconductor (CMOS) integrated circuit process with subsequent bulk-micromachining on wafer-scale. This array is used to demonstrate the feasibility of a low-cost thermal imager. The imager operates in ambient air, without thermal stabilization or cooling. The thermoelectric sensor principle allows one to measure dc radiation signals even without a radiation chopper. Each pixel contains an integrated heater, which allows calibration and self-testing of the imager. Addressing circuitry for the thermopiles and the heaters as well as a low-noise amplifier are integrated with the array on a single chip with a size of 5.5×6.2 mm. The imager achieves a temperature resolution of 530 mK with a low-cost polyethylene Fresnel lens. This performance allows application in presence detection, remote temperature measurement, and building control View full abstract»

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  • Characterization of micromechanical optical modulator

    Publication Year: 2001 , Page(s): 589 - 592
    Cited by:  Papers (2)
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    In this paper, a Fabry-Perot optical modulator fabricated by surface micromechanical technique is presented. The modulator is optimized for a wavelength of 1.3 μm and is intended for a fiber-to-the-home system. The actuation voltage of the modulator is measured to be 10-25 V. The optical modulator has a series of resonant frequencies determined from the device structure. When the modulator is driven by a sinusoidal signal, the output frequency will be doubled. For a driving signal greater than a certain value, the oscillation amplitude of the membrane will exceed λ/4, resulting in an ultrasaturation phenomenon View full abstract»

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  • High-cycle fatigue of single-crystal silicon thin films

    Publication Year: 2001 , Page(s): 593 - 600
    Cited by:  Papers (91)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (122 KB) |  | HTML iconHTML  

    When subjected to alternating stresses, most materials degrade, e.g., suffer premature failure, due to a phenomenon known as fatigue. It is generally accepted that in brittle materials, such as ceramics, fatigue can only take place in toughened solids, i.e., premature fatigue failure would not be expected in materials such as single crystal silicon. The results of this study, however, appear to be at odds with the current understanding of brittle material fatigue. Twelve thin-film (~20 μm thick) single crystal silicon specimens were tested to failure in a controlled air environment (30±0.1°C, 50±2% relative humidity). Damage accumulation and failure of the notched cantilever beams were monitored electrically during the "fatigue life" test. Specimen lives ranged from about 10 s to 48 days, or 1×106 to 1×1011 cycles before failure over stress amplitudes ranging from approximately 4 to 10 GPa. A variety of mechanisms are discussed in light of the fatigue life data and fracture surface evaluation View full abstract»

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  • Low-temperature wafer-level transfer bonding

    Publication Year: 2001 , Page(s): 525 - 531
    Cited by:  Papers (34)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    In this paper, we present a new wafer-level transfer bonding technology. The technology can be used to transfer devices or films from one substrate wafer (sacrificial device wafer) to another substrate wafer (target wafer). The transfer bonding technology includes only low-temperature processes; thus, it is compatible with integrated circuits. The process flow consists of low-temperature adhesive bonding followed by sacrificially thinning of the device wafer. The transferred devices/films can be electrically interconnected to the target wafer (e.g., a CMOS wafer) if required. We present three example devices for which we have used the transfer bonding technology. The examples include two polycrystalline silicon structures and a test device for temperature coefficient of resistance measurements of thin-film materials. One of the main advantages of the new transfer bonding technology is that transducers and integrated circuits can be independently processed and optimized on different wafers before integrating the transducers on the integrated circuit wafer. Thus, the transducers can be made of, e.g., monocrystalline silicon or other high-temperature annealed, high-performance materials. Wafer-level transfer bonding can be a competitive alternative to flip-chip bonding, especially for thin-film devices with small feature sizes and when small electrical interconnections (<3×3 μm2) between the devices and the target wafer are required View full abstract»

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Aims & Scope

The topics of interest include, but are not limited to: devices ranging in size from microns to millimeters, IC-compatible fabrication techniques, other fabrication techniques, measurement of micro phenomena, theoretical results, new materials and designs, micro actuators, micro robots, micro batteries, bearings, wear, reliability, electrical interconnections, micro telemanipulation, and standards appropriate to MEMS. Application examples and application oriented devices in fluidics, optics, bio-medical engineering, etc., are also of central interest.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Christofer Hierold
ETH Zürich, Micro and Nanosystems