Tt 01 Nui
low during the entire test for 100 cycles, suggesting that Z-DOL BW molecules do not get attached or displaced as readily as Z-15 molecules. As a brief summary, the influence of velocity, relative humidity, and temperature on the friction force of mobile Z-15 film is presented in Fig. 17.50. The changing trends are also addressed in this figure. Lack of meniscus reformation decreases friction with increasing velocity Desorption of water and decrease of viscosity decrease friction with increase...
Etching and Substrate Removal
Thin film and bulk substrate etching is another fabrication step that is of fundamental importance to both VLSI processes and micro nanofabrication. In the VLSI area, various conducting and dielectric thin films deposited for passivation or masking purposes must be removed at some point or another. In micro nanofabrication, in addition to thin film etching, very often the substrate silicon, glass, GaAs, etc. also needs to be removed in order to create various mechanical micro- nanostructures...
V 1
Fig. 2.19 a Nanoscaled junctions can be assembled on silicon silicon dioxide supports crossing pairs of orthogonally arranged single-wall carbon nanotubes with chromium gold electrical contacts at their ends. b Nano-transistors can be fabricated contacting the two ends of a single-wall carbon nanotube deposited on an aluminum aluminum oxide gate with gold sources and drain. One or two nanotube transistors can be integrated into nanoscaled NOT c and NOR d logic gates devices. They can be used to...
A Promising Approach To Unimolecular Devices Relies On The Fabrication Of
Fig. 2.18 a Nanoscaled transistors can be fabricated inserting a single molecule 20 or 21 between source and drain electrodes mounted on a silicon silicon dioxide support. b A DNA nanowire can bridge nanoelectrodes suspended above a silicon dioxide support breakage of the gold feature is preceded by the deposition of a dilute toluene solution of C60 20 , junctions with enhanced conduction are obtained. This particular molecule has a diameter of ca. 0. 7 nm and can insert in the nanogap...
Thermal Activation Model of Lubricated Friction
With the discussion of shear in entangled polymer systems we have introduced structural entropy as one of the key players that affect frictional resistance in lubricants. We found that the structural entropy was affected by the load of the slider, which introduces an activation barrier in the form of a critical pressure. The terminology used here resembles the one of the Eyring theory of molecular liquid transport 29.14 . Eyring discussed a pure liquid at rest in terms of a thermal activation...
Thermomechanical AFM Data Storage
In recent years, AFM thermomechanical recording in polymer storage media has undergone extensive modifications mainly with respect to the integration of sensors and heaters designed to enhance simplicity and to increase data rate and storage density. Thermomechanical writing in polycarbonate films and optical readback was first investigated and demonstrated by Mamin and Rugar 1992 . Using heater cantilevers, thermomechanical recording at 30 Gb in2 storage density and data rates of a few Mb s...
O 3 Ipl
Stefan Hengsberger received his diploma in physics from the University of Saarbr cken in 1997. He started as a research scientist at Fraunhofer Miami Florida where he worked until mai 1998. In July 1998 he joined the swiss federal institute of Technology EPFL where he earned his PhD in biomechanics in spring 2002. He stayed for another year at EPFL as a postdoc in biomechanics and physics until summer 2003. Since October 2003 he is Professor of Physics at the University of Applied Science in...
Functional Behavior of Lubricated Friction
Friction-rate experiments are well suited to evaluate the rheological nature of interfacial liquids. In classical theories, such as the Reynolds' hydrodynamic theory discussed above, drag forces in lubricated sliding over thick liquid films were found to depend linearly on the rate of sliding and on the viscosity of the bulk fluid. In high-pressure lubrication, described by the elastohy-drodynamic lubrication theory 29.16,17 , it was found that the linear relationship between friction and...
Functionalization of Oxidized Carbon Nanotubes
Carboxylic groups located at the nanotube tips can be coupled with different chemical groups. Oxidized nanotubes are usually reacted with thionyl chloride SOCl2 to generate the acyl chloride, even if a direct reaction is theoretically possible with alcohols or amines, for example. Reaction of SWNTs with octade-cylamine ODA was reported by Chen et al. 3.201 after reaction of oxidized SWNTs with SOCl2. The functionalized SWNTs have substantial solubility in chloroform CHCl3 , dichloromethane...
Large Angular Deflection and Plate Geometry
Nemirovsky and Bochobza-Degani 35.66 have extended the work to the case of large angle deflections, which included using the trigonometric relationship in the capacitance function and a nonlinear relationship for the mechanical spring constant. These nonlinear relationships were used in the voltage-controlled pull-in equation. In addition, their methodology was extended to planar plates with different shapes Fig. 35.29 . They specifically considered triangular plates the apex of the triangle is...
Molecular Channels and Pumps as Biological Nanotechnology
From a structural perspective, one of the most intriguing features of cellular systems is their division into a number of separate membrane-bound compartments. We have already touched upon this compartmentaliza-tion in the context of self-assembly, and note that the role of membranes and the proteins bound within them is described clearly in Alberts et al. 24.1 . The presence of such compartments, often marked by large concentration gradients with respect to the surrounding medium, hints at...
TrackFollowing Controller Design for a MEMS Microactuator DualStage Servo System
MEMS microactuators for dual-stage servo application are usually designed to have a single flexure resonance mode between 1-2kHz 32.8,40 . This resonance mode is usually very lightly damped and can have a 15 variations due to the differences in the fabrication processes. Since the uncertain resonance frequency is relatively low and close to the open loop gain crossover frequency of the control system, robustness to these variations must be considered in the controller design. Controller Design...
Thermomechanics of Multilayer ThinFilm Microstructures
In this section we describe aspects of the deformation characteristics and stress states in multilayer thin-film microstructures. Deformation and stress states will be considered for microstructures that are both attached to a substrate and freestanding after release from the substrate. In the modeling formalism that we will describe, the substrate simply serves as another layer. We will refer to microstructures as beams and or plates, depending on the relevant dimensions. At times we will use...
Nanotransfer Printing
Nanotransfer printing nTP is a more recent high resolution printing technique, which uses surface chemistries as interfacial glues and release layers rather than inks, as in CP to control the transfer of solid material layers from relief features on a stamp to a substrate 6.33-35 . This approach is purely additive i. e., material is only deposited in locations where it is needed , and it can generate complex patterns of single or multiple layers of materials with nanometer resolution over large...
Physical Vapor Deposition Evaporation and Sputtering
In physical deposition systems the material to be deposited is transported from a source to the wafers, both being in the same chamber. Two physical principles are used to do so evaporation and sputtering. In evaporation, the source is placed in a small container with tapered walls, called a crucible, and heated up to a temperature at which evaporation occurs. Various techniques are utilized to reach the high temperatures needed, including the induction of high currents with coils wound around...
References Onc
19.1 I. L. Singer, H. M. Pollock Eds. Fundamentals of 19.12 Friction Kluwer, Dordrecht 1992 p. 351 19.2 K. Autumn, Y. A. Liang, S.T. Hsieh, W. Zesch etal. 19.13 Adhesive force of a single gecko foot-hair, Nature 19.3 A. L. Baldwin, G. Thurston Mechanics of endothe- 19.14 lial cell architecture and vascular permeability, Critical Rev. Biomed. Eng. 29 2001 247-278 19.4 S. R. White, N.R. Sottos, P. H. Guebelle, J.S. Moore 19.15 et al. Autonomic healing of polymer composites, Nature 409 2001...
Plasticity
Plasticity in thin-film multilayers has been studied in depth for thin metal films on thick substrates see, for example 35.6,37,38 , but little work has been directed toward freestanding multilayers. This is probably because, at least when subject to thermal loading, the stresses are typically smaller in freestanding multilayer films than in systems with thin films on thick substrates see Fig. 35.12 . Many interesting open issues exist with regard to the general issue of plasticity in...
What Is 15.39 In Phase Shift
factor Q, and the natural resonant frequency wo of the free oscillating cantilever, a we obtain - Scant Ad A sin ip A In order to calculate the average power dissipation, 15.32 and 15.33 have to be integrated over one complete oscillation cycle. This yields Note that so far no assumptions have been made regarding how the AFM is operated, except that the motion of the oscillating cantilever has to remain sinusoidal to a good approximation. Therefore, 15.37 is applicable to a variety of different...
Electrochemically Etched STM Tips
For samples with more than a few nanometers of surface roughness, the tip structure in the nanometer-size range becomes an issue. Electrochemical etching can provide tips with reproducible and desirable shapes and sizes Fig. 12.18 , although the exact atomic structure of the tip apex is still not well controlled. The parameters of electrochemical etching depend greatly on the tip material and the desired tip shape. The following is an entirely general description. A fine metal wire 0.1-1 mm...
Youngs Modulus of Polysilicon
The Young's modulus of polysilicon films has been measured using all the techniques discussed in Sect. 34.2.2. A good review of the experimental results taken from bulge testing, tensile testing, beam bending, and lateral resonators are contained in 34.31 . All of the reported results are in reasonable agreement, varying from 130 to 175 GPa, though many values are reported with a relatively high experimental scatter. The main origin of the error in these results is the uncertainties involving...
A Typical Microscope in UHV
A typical AFM for UHV application is shown in Fig. 20.7. The housing 1 contains the light source and a set of lenses that focus the light onto the cantilever. Alternatively, the light can be guided via an optical fiber into the vacuum. By using light emitting diodes with low coherency you avoid disturbing interference effects often found in instruments equipped with lasers as light source. A plane mirror fixed on the spherical rotor of a first stepping motor 2 can be rotated Fig. 20.7 Schematic...
Electromechanics Parallel Plate Stabilization
An important practical consideration is the stabilization of the parallel plate electrostatic actuator. Seeger et al. 35.69 and Nemirovsky et al. 35.66 showed that the addition of a series capacitance feedback capacitance stabilizes the actuator such that it does not pull-in to the substrate. The series capacitance and the variable actuator capacitance combine to form a voltage divider that provides passive control of the voltage across the actuator. In this case, Nemirovsky et al. 35.66...
Tribological Issues in MEMSNEMS
Tribological issues are important in MEMS NEMS requiring intended and or unintended relative motion. In MEMS NEMS, various forces associated with the device scale down with size. When the length of the machine decreases from 1 mm to 1 m, the area decreases by a factor of a million and the volume decreases by a factor of a billion. As a result, surface forces such as adhesion, friction, meniscus forces, viscous drag forces, and surface tension that are proportional to area become a thousand...
Tt 01 Srp
The SmCo magnets produce a measured magnetic field intensity of 0.14T at the mid-thickness of the coils. The effective coil length is 320 mm, yielding an expected force Fxy of 45 N per mA of drive current. The principal design issue of the spring system is the ratio of its stiffnesses for in-plane and out-of-plane motion. Whereas for many scanning probe applications the required z-axis range need not be much larger than a few microns, it is necessary to ensure that the z-axis retraction of the...
Local Mechanical Spectroscopy by Contact AFM
Mechanical properties of solids elasticity, anelasticity, plasticity are generally measured on macroscopic samples. But many phenomena in materials science require measurements of mechanical properties at the surface of a material or at the interfaces between thin layers deposited on a surface. High spatial resolution is also important, for example in the cases of multiphased materials or composite materials, phase transitions, lattice softening in shape-memory alloys, precipitation in light...
FIB tips
A common AFM application in integrated circuit manufacture and MEMs is to image structures with very steep sidewalls such as trenches. To accurately image these features, one must consider the micron-scale tip structure, rather than the nanometer-scale structure of the tip apex. Since tip fabrication processes rely on anisotropic etchants, the cone half-angles of pyramidal tips are approximately 20 degrees. Images of deep trenches taken with such tips display slanted sidewalls and may not reach...
i if Xtk
ed. byS.T. Pantelides, M.A. Reed, J. Murday, A. Avi-ran Materials Research Society Press, Pittsburgh 2000 582 H10.3 1 6 4.25 4.7 C. R. Martin Nanomaterials A membrane-based synthetic approach, Science 266 1994 1961-1966 4.8 G.A. Ozin Nanochemistry synthesis in diminishing dimensions, Adv. Mater. 4 1992 612-649 4.9 R.J. Tonucci, B. L. Justus, A.J. Campillo, C. E. Ford 4.26 Nanochannel array glass, Science 258 1992 783-785 4.10 J.Y. Ying Nanoporous systems and templates, Sci. Spectra 18 1999...
Piezo Relaxation and Hysteresis
The last important benefit from low-temperature operation of SPMs is that artifacts given by the response of the piezoelectric scanners are substantially reduced. After applying a voltage ramp to one electrode of a piezoelectric scanner, its immediate initial deflection, I0, is followed by a much slower relaxation, Al, with a logarithmic time dependence. This effect, known as piezo relaxation or creep, diminishes substantially at low temperatures, typically by a factor of ten or more. As a...
Wet Etching
Historically, wet etching techniques preceded the dry ones. These still constitute an important group of etchants for micro nanofabrication, in spite of their less frequent application in the VLSI processes. Wet etchants are by and large isotropic and show superior selectivity to the masking layer compared to various dry techniques. In addition, due to the lateral undercut, the minimum feature achievable with wet etchants is limited to gt 3 m. Silicon dioxide is commonly etched in a dilute 6...
VLS Method for Nanowire Synthesis
Some of the recent successful syntheses of semiconductor nanowires are based on the so-called vapor-liquid-solid VLS mechanism of anisotropic crystal growth. This mechanism was first proposed for the growth of single crystal silicon whiskers 100 nm to hundreds of microns in diameter 4.87 . The proposed growth mechanism see Fig. 4.5 involves the absorption of source material from the gas phase into a liquid droplet of catalyst a molten particle of gold on a silicon substrate in the original work...
Zt
Fig. 4.32 Optimal ZT calculated as a function of segment length for 10-nm diameter PbSe PbS nanowires at 77 K, where optimal refers to the placement of the Fermi level to optimize ZT. The optimal ZT for 10-nm diameter PbSe, PbS, and PbSeo.sSo.5 nanowires are 0.33, 0.22, and 0.48, respectively 4.141 Fig. 4.32 Optimal ZT calculated as a function of segment length for 10-nm diameter PbSe PbS nanowires at 77 K, where optimal refers to the placement of the Fermi level to optimize ZT. The optimal ZT...
Commercial AFM
A review of early designs of AFMs is presented by Bhushan 11.4 . There are a number of commercial AFMs available on the market. Major manufacturers of AFMs for use in an ambient environment are Digital Instruments Inc., a subsidiary of Veeco Instruments, Inc., Santa Barbara, California Topometrix Corp., a subsidiary of Veeco Instruments, Inc., Santa Clara, California other subsidiaries of Veeco Instruments Inc., Woodbury, New York Molecular Imaging Corp., Phoenix, Arizona Quesant Instrument...
Info Ssk
3.227 J. Kong, M.G. Chapline, H. Dai Functionalized car- 3.242 bon nanotubes for molecular hydrogen sensors, Adv. Mater. 13 2001 1384-1386 3.228 F. Rodriguez-Reinoso The role of carbon materials 3.243 in heterogeneous catalysis, Carbon 36 1998 159175 3.229 E. Auer, A. Freund, J. Pietsch, T. Tacke Carbon as 3.244 support for industrial precious metal catalysts, Appl. 3.230 J.M. Planeix, N. Coustel, B. Coq, B. Botrons, P.S. Kumbhar, R. Dutartre, P. Geneste, P. Bernier, 3.245 P.M. Ajayan...
Biomolecules in Therapeutic Nanodevices SelfAssembly and Orthogonal Conjugation
Biological macromolecules undergo self-assembly at multiple levels, and like all instances of such construction, biological self-assembly processes are driven by thermodynamic forces. Some biomolecules undergo intramolecular self-assembly as in protein folding from linear peptide sequences, Fig. 10.10 . Higher order structures are, in turn, built by self-assembly of smaller self-assembled subunits for instance, structures assembled by hybridization of multiple oligonucleotides, enzyme...
Info Kex
N. Tas, T. Sonnenberg, H. Jansen, R. Legtenberg, M. Elwenspoek Stiction in surface micromachining, J. Micromech. Microeng. 6 1996 385-397 R. Maboudian, R.T. Howe Critical review adhesion in surface micromechanical structures, J. Vac. Sci. Technol. B 15 1 1997 1-20 J. H. Smith, S. Montague, J.J. Sniegowski, J. R. Murray, P.J. McWhorter Embedded micromechanical devices for the monolithic integration of MEMS with CMOS, Proc. Int. Electron Devices Meeting, Washington 1995, 609-612 R. S. Muller, K....
Cantilever Biosensors
Micromechanical cantilevers discussed above in conjunction with force microscopy, Fig. 10.6 transduce sensed events by mechanical means 10.82 . Both changes in the resonant frequency and deflection of cantilevers resulting from analyte binding or dissociation can be conveniently and sensitively detected. These changes in cantilever state can be conveniently detected by optical, capacitive, interferometry, or piezoresistive piezoelectric methods, among others. Microfabricated cantilever...
Gaseous Carbon SourceBased Production Techniques for Carbon Nanotubes
As mentioned in the introduction of this chapter, the catalysis-enhanced thermal cracking of gaseous carbon source hydrocarbons, CO - commonly referred to as catalytic chemical vapor deposition CCVD -has been known to produce carbon nanofilaments for a long time 3.4 , so that reporting all the works published in the field since the beginning of the century is almost impossible. Until the 90s, however, carbon nanofilaments were mainly produced to act as a core substrate for the subsequent growth...
Dry Etching
Most dry etching techniques are plasma-based. They have several advantages compared with wet etching. These include smaller undercut allowing smaller lines to be patterned and higher anisotropicity allowing high-aspect-ratio vertical structures . However, the selectivity of dry etching techniques is lower than the wet etchants, and one must take into account the finite etch rate of the masking materials. The three basic dry etching techniques, namely, high-pressure plasma etching, reactive ion...
Editors Vita
Dr. Bharat Bhushan received an M.S. in mechanical engineering from the Massachusetts Institute of Technology in 1971, an M.S. in mechanics and a Ph.D. in mechanical engineering from the University of Colorado at Boulder in 1973 and 1976, respectively, an MBA from Rensselaer Polytechnic Institute at Troy, NY in 1980, Doctor Technicae from the University of Trondheim at Trondheim, Norway in 1990, a Doctor of Technical Sciences from the Warsaw University of Technology at Warsaw, Poland in 1996,...