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Kevin A. Shaw

Other affiliations: Cornell University
Bio: Kevin A. Shaw is an academic researcher from Ithaca College. The author has contributed to research in topics: Reactive-ion etching & Acceleration. The author has an hindex of 17, co-authored 31 publications receiving 1740 citations. Previous affiliations of Kevin A. Shaw include Cornell University.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a single-crystal slhcon, high aspect ratlo, low-temperature process sequence for the fabelfcatlon of suspended movable smgle-crystals s&on (SCS) beam structures is presented.
Abstract: A single-crystal slhcon, high aspect ratlo, low-temperature process sequence for the fabrlcatlon of suspended rmcroelectromechamcal structures (MEMS) usmg a smgle hthography step and reactwe Ion etching (RIE) IS presented The process IS called SCRJZAM I (single-crystal reactwe etchmg and metalhzatmn) SCREAM I IS a bulk mlcromachmmg process that uses RIE of a s~hcon substrate to fabricate suspended movable smgle-crystal s&on (SCS) beam structures Beam elements wth aspect ratios of 10 to 1 and widths rangmg from 0 5 to 4 0 Frn have been fabricated All process steps are low temperature (<3OO “C), and only conventronal sd~con fabrlcation tools are used photohthography, RIE, MIE, plasma-enhanced chemxal-vapor deposrtlon (PECVD) and sputter deposlhon SCREAM I IS a self-ahgned process and uses a smgle lithography step to define beams and structures srmultaneously as well as all necessary contact pads, electrIcal mterconnects and lateral capaators SCREAM I has been specifically deslgned for integration with standard Integrated cmxnt (IC) processes, so MEM deuces can be fabricated adjacent to prefabricated analog and dIgItal carcuitry In this paper we present process parameters for the fabncatlon of discrete SCREAM I devices We also discuss mask design rules and show micrographs of fabncated deuces

295 citations

Patent
03 Dec 1993
TL;DR: In this paper, a single mask, low temperature reactive ion etching process for fabricating high aspect ratio, released single crystal microelectromechanical structures independent of crystal orientation is described.
Abstract: The invention provides a single mask, low temperature reactive ion etching process for fabricating high aspect ratio, released single crystal microelectromechanical structures independent of crystal orientation. A dielectric mask (12) on a single-crystal substrate (154) is patterned to define isolating trenches. A protective conformal layer (28) is applied to the resultant structure. The conformal layer (28) on the floor of the trenches is removed and a second etch deepens the trench to expose the mesa walls which are removed during the release step by isotropic etching. A metal layer (44) is formed on the resultant structure providing opposed plates (156) and (158) of a capacitor. The cantilever beam (52) with the supporting end wall (152) extends the grid-like structure (150) into the protection of the deepened isolation trenches (54). A membrane can be added to the released structures to increase their weight for use in accelerometers, and polished for use as movable mirrors.

208 citations

Proceedings ArticleDOI
23 Jun 1995
TL;DR: In this article, actuators were used to tune the resonant frequency of micromechanical oscillators, and the results showed that resonant oscillations from 7.7% to 146% of the original frequency can be achieved.
Abstract: We present actuators which tune the resonant frequency of micromechanical oscillators. Experimental results show resonant oscillations from 7.7% to 146% of the original resonant frequency. Numerical results substantiate these results. Two failure modes have been identified which limit

206 citations

Patent
23 May 1994
TL;DR: In this article, a microelectromechanical accelerometer (60) having submicron features is fabricated from a single crystal silicon substrate, which includes a movable portion incorporating an axial beam (102) carrying laterally-extending high aspect ratio released fingers (110-117, 120-127) cantilevered above the floor of a cavity formed in the substrate during the fabrication process.
Abstract: A microelectromechanical accelerometer (60) having submicron features is fabricated from a single crystal silicon substrate (10). The accelerometer includes a movable portion incorporating an axial beam (102) carrying laterally-extending high aspect ratio released fingers (110-117, 120-127) cantilevered above the floor of a cavity formed in the substrate during the fabrication process. The movable portion is supported by restoring springs (132, 142) having controllable flexibility to vary the resonant frequency of the structure. A multiple-beam structure provides stiffness in the movable portion for accuracy.

172 citations

Journal ArticleDOI
TL;DR: In this paper, a combination of electrostatic actuators is used to tune the linear and nonlinear stiffness coefficients of a uniaxial micromechanical device without affecting the resonant frequency or the linear stiffness.
Abstract: Using a combination of electrostatic actuators, we present a method to independently tune the linear and nonlinear stiffness coefficients of a uniaxial micromechanical device. To demonstrate the method's capability, we investigated the tuning of an oscillator with linear and cubic restoring forces. We successfully tuned the cubic stiffness from 0.31/spl times/10/sup 11/ to -5.1/spl times/10/sup 11/ N/m/sup 3/ without affecting the resonant frequency or the linear stiffness. Numerical results are presented which characterize the actuators and indicate important design parameters. Finally, issues such as actuator design, quadratic stiffness, and stability are discussed.

103 citations


Cited by
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Book
Nadim Maluf1
30 Nov 2000
TL;DR: The main aim is to provide an introduction to MEMS by describing the processes and materials available and by using examples of commercially available devices, and the concept of using MEMS devices as key elements within complex systems (or even microsystems!) is explored.
Abstract: If you've not been involved in MEMS (MicroElectroMechanical Systems) technology or had the cause to use MEMS devices, then you may wonder what all the fuss is about. What are MEMS anyway? What's the difference between MEMS and MST (MicroSystems Technology)? What are the advantages over existing technologies? If you have ever found yourself pondering over such questions, then this book may be for you. As the title suggests, the main aim is to provide an introduction to MEMS by describing the processes and materials available and by using examples of commercially available devices. The intended readership are those technical managers, engineers, scientists and graduate students who are keen to learn about MEMS but have little or no experience of the technology. I was particularly pleased to note that Maluf has dedicated a whole chapter to the important (and often difficult) area of packaging. The first three chapters provide a general overview of the technology. Within the first three pages we are introduced to the MEMS versus MST question, only to discover that the difference depends on where you live! The United States prefer MEMS, while the Europeans use the handle MST. (Note to self: tell colleagues in MEMS group at Southampton). A good account is given of the basic materials used in the technology, including silicon, silicon oxide/nitride/carbide, metals, polymers, quartz and gallium arsenide. The various processes involved in the creation of MEMS devices are also described. A good treatment is given to etching and bonding in addition to the various deposition techniques. It was interesting to note that the author doesn't make a big issue of the differences between bulk and surface micromachined devices; the approach seems to be `here's your toolbag - get on with it'. One of the great strengths of this book is the coverage of commercial MEMS structures. Arising as they have, from essentially a planar technology, MEMS devices are often elaborate three-dimensional creations, and 2D drawings don't do them much justice. I have to say that I was extremely impressed with the many aesthetic isometric views of some of these wonderful structures. Pressure sensors, inkjet print nozzles, mass flow sensors, accelerometers, valves and micromirrors are all given sufficient treatment to describe the fundamental behaviour and design philosophy, but without the mathematical rigour expected for a traditional journal paper. Chapter 5 addresses the promise of the technology as a means of enabling a new range of applications. The concept of using MEMS devices as key elements within complex systems (or even microsystems!) is explored. The so-called `lab-on-a-chip' approach is described, whereby complex analytical systems are integrated onto a single chip together with the associated micropumps and microvalves. The design and fabrication of MEMS devices are important issues by themselves. A key area, often overlooked, is that of packaging. Painstaking modelling and intricate fabrication methodologies can produce resonator structures oscillating at precisely, say, 125 kHz. The device is then mounted in a dual-in-line carrier and the frequency shifts by 10 kHz because of the additional internal stresses produced. Packaging issues can't be decoupled from those of the micromachined components. Many of these issues, such as protective coatings, thermal management, calibration etc, are covered briefly in the final chapter. Overall, I found this book informative and interesting. It has a broad appeal and gives a good insight into this fascinating and exciting subject area. Neil White

770 citations

Journal ArticleDOI
01 Aug 1998
TL;DR: Surface micromachining is characterized by the fabrication of micromechanical structures from deposited thin films as discussed by the authors, which typically requires that they be freed from the planar substrate.
Abstract: Surface micromachining is characterized by the fabrication of micromechanical structures from deposited thin films. Originally employed for integrated circuits, films composed of materials such as low-pressure chemical-vapor-deposition polycrystalline silicon, silicon nitride, and silicon dioxides can be sequentially deposited and selectively removed to build or "machine" three-dimensional structures whose functionality typically requires that they be freed from the planar substrate. Although the process to accomplish this fabrication dates from the 1960's, its rapid extension over the past few years and its application to batch fabrication of micromechanisms and of monolithic microelectromechanical systems (MEMS) make a thorough review of surface micromachining appropriate at this time. Four central issues of consequence to the MEMS technologist are: (i) the understanding and control of the material properties of microstructural films, such as polycrystalline silicon, (ii) the release of the microstructure, for example, by wet etching silicon dioxide sacrificial films, followed by its drying and surface passivation, (iii) the constraints defined by the combination of micromachining and integrated-circuit technologies when fabricating monolithic sensor devices, and (iv) the methods, materials, and practices used when packaging the completed device. Last, recent developments of hinged structures for postrelease assembly, high-aspect-ratio fabrication of molded parts from deposited thin films, and the advent of deep anisotropic silicon etching hold promise to extend markedly the capabilities of surface-micromachining technologies.

663 citations

Journal ArticleDOI
TL;DR: The typical power requirements of some current portable devices, including a body sensor network, are shown in Figure 1.
Abstract: Wireless sensor nodes (WSNs) are employed today in many different application areas, ranging from health and lifestyle to automotive, smart building, predictive maintenance (e.g., of machines and infrastructure), and active RFID tags. Currently these devices have limited lifetimes, however, since they require significant operating power. The typical power requirements of some current portable devices, including a body sensor network, are shown in Figure 1.

611 citations

Journal ArticleDOI
TL;DR: In this paper, the Black Silicon Method was used to find the processing conditions needed for a vertical wall in a Reactive Ion Etchers (RIE); two parallel plate reactors and a hexode.
Abstract: Very deep treches (up to 200 um) with high aspect ratios (up to 10) in silicon are etched using a fluorine-based plasma (SF6/O2/CHF3). Isotropic, positively and megatively (i.e. reverse) tapered as well as fully vertical walls with smooth surfaces are achieved by controlling the plasma chemistry. A convenient way to find the processing conditions needed for a vertical wall is described: the Black Silicon Method. This new procedure is checked for three different Reactive Ion Etchers (RIE); two parallel plate reactors and a hexode. The influence of the r.f. power, pressure, and gas mixture on the profile will be shown. Scanning Electron Microscope (SEM) photos are included to demonstrate the Black Silicon Method, the influence of the gases on the profile, and the use of this method in fabricating Micro Electro Mechanical Systems (MEMS).

602 citations

Journal ArticleDOI
TL;DR: The use of various materials, such as silicon, glass and polymers, and their related technologies for the manufacturing of simple microchannels and complex systems is discussed in this paper.
Abstract: Microfluidics is an emerging field that has given rise to a large number of scientific and technological developments over the last few years. This review reports on the use of various materials, such as silicon, glass and polymers, and their related technologies for the manufacturing of simple microchannels and complex systems. It also presents the main application fields concerned with the different technologies and the most significant results reported by academic and industrial teams. Finally, it demonstrates the advantage of developing approaches for associating polymer technologies for manufacturing of fluidic elements with integration of active or sensitive elements, particularly silicon devices.

579 citations