Pressure Sensor

Pressure sensors are one of the early devices realized by silicon micromachining technologies and have become successful commercial products. The devices have been widely used in various industrial and biomedical applications. The sensors can be based on piezoelectric, piezoresistive, capacitive, and resonant sensing mechanisms. Silicon bulk and surface micromachining techniques have been used for sensor batch fabrication, thus achieving size miniaturization and low cost. Two types of pressure...

Info

Fig. 4.18a-d STM height images, obtained in the constant current mode, of MoSe chains deposited on an Au(111) substrate. (a) A single chain image, and (b) a MoSe wire bundle. (c) and (d) Images of MoSe wire fragments containing 5 and 3 unit cells, respectively 4.119 . The scale bars are all 1 nm Fig. 4.18a-d STM height images, obtained in the constant current mode, of MoSe chains deposited on an Au(111) substrate. (a) A single chain image, and (b) a MoSe wire bundle. (c) and (d) Images of MoSe...

O 3

19 Scanning Probe Studies of Nanoscale Adhesion Between Solids in the Presence of Liquids and Monolayer 19.1 The Importance of Adhesion at the 19.2 Techniques for Measuring Adhesion 19.3 Calibration of Forces, Displacements, and 19.3.1 Force 19.3.2 Probe Tip 19.3.3 Displacement Calibration 19.4 The Effect of Liquid Capillaries on 19.4.1 Theoretical 19.4.2 Experimental and Theoretical Studies of Capillary Formation with Scanning 19.4.3 Future Directions 19.5 Self-Assembled 19.5.1 Adhesion at SAM...

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Reichl Packaging and interconnection of sen- 37.46 sors, Sens. Actuators A 25-27 (1991) 63-71 37.32 A. Grisel, C. Francis, E. Verney, G. Mondin Packaging technologies for integrated electrochemical 37.47 sensors, Sens. Actuators 17 (1989) 285-295 37.33 J.L. Lund, K. D. Wise Chip-level encapsulation of implantable CMOS microelectrode arrays, 1994 Solid-State Sensor and Actuator Workshop, Hilton 37.48 Head (1994) 29-32 37.34 T. Akin, B. Siaie, K. Najafi Modular micromachined high-density...

Current Challenges and Future Trends

Although the field of MEMS has experienced significant growth over the past decade, many challenges still remain. In broad terms, these challenges can be grouped into three general categories (1) fabrication, (2) packaging, and (3) application. Challenges in these areas will, in large measure, determine the commercial success of a particular MEMS device, both in technical and economic terms. The following presents a brief discussion of some of these challenges, as well as possible approaches to...

Perfluoropolyether Lubricants

The classical approach to lubrication uses freely supported multimolecular layers of liquid lubricants 33.49, 54,55 . The liquid lubricants are sometimes chemically bonded to improve their wear resistance. Partially chemically bonded, molecularly thick perfluoropolyether (PFPE) lubricants are widely used for lubrication of magnetic storage media 33.35 and are suitable for MEMS NEMS devices. Adhesion, friction, and durability experiments have been performed on virgin Si(100) surfaces and silicon...

Field Effect Transistor Biosensors

Field effect transistor (FET) architectures are another sensing architecture that can be conveniently produced by micro-nanofabrication. FETs consist of a current source, a current drain, a conductive path (sensing channel) between them, and a sensing gate to which a bias can be applied. Analyte binding to the sensing channel induces a charge transfer resulting in a dipole between the surface and the underlying depletion region of the semiconductor current that passes between the source and...

The Reticuloendothelial System and Clearance of Foreign Materials

Physical properties such as surface chemistry and particle size can drive targeting of nanomaterials (and presumably nanodevices containing them) to some tissues. For instance, the pharmacokinetic (Pk) and biodistribution (Bd) properties 10.32 of many drugs and nanomaterials are driven by their clearance in urine, which is in turn governed by the filtration preferences of the kidney. Most molecules making transit into urine have masses of less than 25 to 50 kilodaltons (kDa 25-50 kDa particles...

And Template Manufacturing

Particle Silica Self Assembly

Self-assembly is a nanofabrication technique that involves aggregation of colloidal nano-particles into the final desired structure 5.86 . This aggregation can be either spontaneous (entropic) and due to the thermo- Physical Self-Assembly. This is an entropic-driven method that relies on the spontaneous organization of colloidal particles into a relatively stable structure through non-covalent interactions. For example, colloidal polystyrene spheres can be assembled into a 3-D structure on a...

Commercial STMs

There are a number of commercial STMs available on the market. Digital Instruments, Inc. located in Santa Barbara, CA introduced the first commercial STM, the Nanoscope I, in 1987. In a recent Nanoscope IV STM for operation in ambient air, the sample is held in position while a piezoelectric crystal in the form of a cylindrical tube (referred to as PZT tube scanner) scans the sharp metallic probe over the surface in a raster pattern while sensing and outputting the tunneling current to the...

Closure

At most solid-solid interfaces of technological relevance, contact occurs at many asperities. A shaip AFM FFM tip sliding on a surface simulates just one such contact. However, asperities come in all shapes and sizes. The effect of radius of a single asperity (tip) on the friction adhesion performance can be studied using tips of different radii. AFM FFM are used to study various tribological phenomena, including surface roughness, adhesion, friction, scratching, wear, indentation, detection of...

References

Bhushan Magnetic Recording Surfaces. In 28.19 Characterization of Tribological Materials, ed. by W. A. Glaeser (Butterworth-Heinemann, Boston 1993) pp. 116-133 28.2 B. Bhushan Principles and Applications ofTribol- ogy (Wiley, New York 1999) 28.20 28.3 B. Bhushan Introduction to Tribology (Wiley, New York 2002) 28.4 V.J. Novotny, I. Hussla, J. M. Turlet, M.R. Philpott Liquid polymer conformation on solid surfaces, 28.21 J. Chem. Phys. 90 (1989) 5861-5868 28.5 V.J. Novotny Migration of...

Effect of Tip Radii and Humidity on Adhesion and Friction

The tip radius and relative humidity affect adhesion and friction for dry and lubricated surfaces 17.23,36 . Eigure 17.22 shows the variation of single-point adhesive-force measurements as a function of tip radius on a Si(100) sample for several humidities. The adhesive force data are also plotted as a function of relative humidity for several tip radii. The general trend at humidities up to the ambient is that a 50-nm radius SisN4 tip exhibits a slightly lower adhesive force compared to the...

Upr A8011 Cnrs

Centre d'Elaboration des Mat riaux et d'Etudes Structurales (CEMES) 29 Rue Jeanne Marvig 31055 Toulouse Cedex 4, France e-mail monthiou cemes.fr e-mail mmorgens physnet.uni-hamburg.de Department of Electronic Engineering Yamada-Oka 2-1 565-0871 Suita-Citiy, Osaka, Japan e-mail smorita ele.eng.osaka-u.ac.jp e-mail mukasa nano.eng.hokudai.ac.jp University of Western Ontario Department of Applied Mathematics WSC139, Faculty of Science London, Ontario N6A 5B7, Canada e-mail mmuser uwo.ca University...

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Bode plot 976 Bohr radius of excitons 135 Boltzmann ansatz 482 Boltzmann distribution 887 bond - breakage 483 i i - lifetime 482 bonded lubricant film 864 bonded PFPE 1012 bonding - kinetics 893 -techniques 1114 bone - ion implantation 330 bottom-up - chemical strategies 10 -materials 281 - film formation 861 -lubricant 729,861 - lubricant film 832 -lubrication 530,569-571,580, bovine serum albumin (BSA) 476 bpsi (bits per square inch) 901 BPT (1, 1'-biphenyl-4-thiol) 854, 1007 BPTC...

Using Wet Etch and Wafer Bonding

The use of anisotropic wet etchants to remove silicon can be regarded as the beginning of the micromachining era. Back side etch was used to create movable structures such as beams, membranes, and plates, Fig. 5.20. Initially, the etching was timed to create a specified thickness. However, this technique proved inadequate in creating thin structures (< 20 m). Subsequent use of various etch stop techniques allowed the creation of thinner membranes in a more controlled fashion. As mentioned in...

Quantum Structure Nanofabrication Using Epitaxy on Patterned Substrates

There have been several different approaches to the fabrication of quantum wires and dots using epitaxial layers. The most straight forward technique involves e-beam lithography and etching of an epitaxial grown layer (e.g., InGaAs on GaAs substrate) 5.63 . However, due to the damage and or contamination during lithography, this method is not very suitable for active device fabrica- Fig. 5.48 (a) InGaAs quantum wire fabricated in a V-groove InP and (b) AlGaAs quantum wire fabricated through...

Tt 01

Fig. 16.4 Experimental setup of the biomembrane force probe (BFP). The spring in the BFP is a pressurized membrane capsule. Its spring constant is set by the membrane tension, which is controlled by micropipette suction. The BFP tip, a glass microbead of 1-2 im diameter, was chemically glued to the membrane. Operated on the stage of an inverted microscope, the BFP (on the left) was kept stationary and the microbead test surface (on the right) was translated to from contact with the BFP tip by...

Quantum Structure Nanofabrication Using Strain Induced Self Assembly

A more recent technique for fabricating quantum wires and dots involves strain-induced self-assembly 5.62, 65 . The term self-assembly represents a process whereby a strained 2-D system reduces its energy by a transition into a 3-D morphology. The most commonly used material combination for this technique is the InxGai-xAs GaAs system, which offers a large lattice mismatch (7.2 betweenInAs andGaAs) 5.66,67 , although recently Ge dots on Si substrate have also attracted considerable attention...

Microfluidic Multiplexer Integrated with Passive Microdispenser

Ahn et al. 9.19 have demonstrated the sPROMs technology to be an innovative method of controlling liquid Fig. 9.19a-f Microphotographs of microdispenser sequence (a) fabricated device (b) fluid at reservoir inlet (c) reservoir filling (d) reservoir filled (e) split in liquid column due to pneumatic actuation and (f) fluid ejected to measurement channel and locked in by passive valve. After 9.58 , reproduced by permission of The Royal Society of Chemistry Fig. 9.19a-f Microphotographs of...

Nanotherapeutic Devices in Oncology

The economic burden imposed by cancer is immense, measuring in the billions of dollars annually in the United States alone. Existing therapies such as surgical resection, radiotherapy, and chemotherapy have profoundly limited efficacy and frequently provide unfavorable outcomes as the result of catastrophic therapeutic side effects. Additionally, the biology, chemistry, and physics of cancer, in general, and solid tumors in particular, provide therapeutic avenues accessible only by nanoscale...

Introduction Types of Surface Forces

In this chapter, we discuss the most important types of surface forces and the relevant equations for the force and friction laws. Several different attractive and repulsive forces operate between surfaces and particles. Some forces occur in vacuum, for example, attractive van der Waals and repulsive hard-core interactions. Other types of forces can arise only when the interacting surfaces are separated by another condensed phase, which is usually a liquid. The most common types of surface...

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Senturia, R. L. Smith, 25.23 R. M. White Microsensors (IEEE, New York 1990) 25.2 I. Fujimasa Micromachines A New Era in Mechanical Engineering (Oxford Univ. Press, Oxford 1996) 25.3 W. S. Trimmer (Ed.) Micromachines and MEMS, 25.24 Classic and Seminal Papers to 1990 (IEEE, New York 25.4 B. Bhushan Tribology Issues and Opportunities in MEMS (Kluwer, Dordrecht 1998) 25.25 25.5 G.T. A. Kovacs Micromachined Transducers Sourcebook (WCB McGraw-Hill, Boston 1998)...

Spm

Have been used for nanofabrication 11.4,10,45-47 and nanomachining 11.48 . STMs and AFMs are used at extreme magnifications ranging from 103 to 109 in x, y and z directions for imaging macro to atomic dimensions with high resolution information and for spectroscopy. These instruments can be used in any environment such as ambient air 11.2,49 , various gases 11.17 , liquid 11.50-52 , vacuum 11.1,53 , at low temperatures (lower than about 100 K) 11.54-58 and high temperatures 11.59,60 . Imaging...

Parylene

Parylene (poly-paraxylylene) is another emerging polymeric MEMS material due in large part to its biocompatibility. It is particularly attractive from the fabrication perspective, because it can be deposited by CVD at room temperature. Moreover, the deposition process is conformal, which enables parylene coatings to be applied to prefabricated structures, such as Si mi-croneedles 7.94 , low stress silicon nitride membrane particle filters 7.95 , and micromachined polyimide Au optical scanners...

Su8

SU-8 is a negative-tone, epoxy-like photoresist that is receiving much attention for its versatility in MEMS processing. It is a high-aspect-ratio, UV-sensitive resist designed for applications requiring single-coat resists with thicknesses on the order of 500 microns 7.90 . SU-8 has favorable chemical properties that enable it to be used as a molding material for high-aspect-ratio electroplated structures (as an alternative to LIGA), and as a structural material for microfluidics 7.90 . In...

Oh Oh

For printing onto flexible and rigid substrates with hard inorganic and soft polymer stamps. Figure 6.6 presents a set of procedures for using nTP to pattern a thin metal bilayer of Au Ti with a surface transfer chemistry that relies on a dehydration reaction 6.33 . The process begins with fabrication of a suitable stamp. Elastomeric stamps can be built using the same casting and curing procedures described for CP. Rigid stamps can be fabricated by (1) patterning resist (e.g., electron beam...

Atomic Level Analysis of Biological Systems

As already described in the introduction, one of the intriguing roles of nanotechnology in the biological setting is that it has brought the Instron technology of traditional solid mechanics to the nanoscale and has permitted the investigation of the force-extension characteristics of nanoscale systems (macromolecules and their assemblies, in particular). As noted earlier, mechanical force spectroscopy 24.20 is emerging as a profound tool for exploring the connection between structure, force,...

System Interface

MEMS products are mounted in systems that have much greater mass than the device itself. For this reason, it is difficult to transmit a mechanical shock wave to a MEMS sensor that is sufficient to cause failure after it is installed in a module. However, failures are possible when the devices are handled during module assembly. Improper functional response is also possible if the module mount system has a mechanical resonance that amplifies or reduces mechanical transmission under different...

Modeling at the Nano Bio Interface

We have already provided a number of different views of the biology-nanotechnology interface, all of which reveal the insights that can emerge from model building. Indeed, one of the key thrusts of this entire chapter is the view that as the type of data that emerges concerning biological systems becomes increasingly quantitative, it must be responded to with models that are also quantitative 24.30 . The plan of this section is to show how atomistic and continuum analyses each offer insights...

Acknowledgements

Dresselhaus, Yu-Ming Lin, Oded Rabin, Marcie R. Black, Gene Dresselhaus The authors gratefully acknowledge the stimulating discussions with Professors Charles Lieber, Gang Chen, S.T. Lee, Arun Majumdar, Peidong Yang, and JeanPaul Issi, Dr. Joseph Heremans, and Ted Harman. The authors are grateful for support for this work by the ONR Grant 000140-21-0865, the MURI program subcontract PO 0205-G-7A114-01 through UCLA, and DARPA contract N66001-00-1-8603. 6 Stamping Techniques for...

Package and Test

IC packages are environmental (mechanical, chemical, electromagnetic, optical) barriers that protect the chips from surrounding media. Only power and electrical signals and inertial forces pass unimpeded, so most MEMS sensors and actuators require that this barrier be selectively penetrated. Package and test functions are unique to each company's design and MEMS product type. Standard semiconductor packaging equipment and processes are modified when possible. However, even the line of...

Amontons Law and Deviations from It Due to Adhesion The Cobblestone Model

Early theories and mechanisms for the dependence of friction on the applied normal force or load, L, were developed by da Vinci, Amontons, Coulomb and Euler 18.228 . For the macroscopic objects investigated, the friction was found to be directly proportional to the load, with no dependence on the contact area. This is described by the so-called Amontons' law Experimentally, it has been found that during both smooth and stick-slip sliding the local geometry of the contact zone remains largely...

E

The magnitude of the end deflection can be measured by microscopy, optical interferometry, or any other technique. Another useful structure for measuring stress gradients is a spiral. For this structure, the end of the spiral not anchored to the substrate will move out-of-plane. Also Fig.34.3a,b Schematic (a) top view and (b) side view of Guckel ring structures 34.8 . The dashed lines in (a) indicate the anchors Fig.34.3a,b Schematic (a) top view and (b) side view of Guckel ring structures 34.8...

U1

Point B, when the adhesion force upon further approach would become larger than the spring restoring force, the tip will suddenly jump to point C. We can then probe the predominantly repulsive force interaction by further reducing the tip-sample distance. Then, while retracting the tip, we will pass point C, because the tip is still in a local energy minimum. At position D the tip will jump suddenly to point A again, since the restoring force now exceeds the adhesion. From Fig. 15.2 we can see...

Nj Nj

Aluminum metallizations by continuous indentation and X-ray stress measurement techniques, J. Mater. Res. 6 (1991) 2084-2090 22.83 22.68 T. Y. Tsui, W. C. Oliver, G.M. Pharr Influences of stress on the measurement of mechanical properties using nanoindentation. 1. Experimen- 22.84 tal studies in an aluminum alloy, J. Mater. Res. 11 22.69 T. Y. Tsui, J. Vlassak, W. D. Nix Indentation plastic displacement field Part I. The case of soft films on 22.85 hard substrates, J. Mater. Res. 14 (1999)...

Nano Tools Nano Devices Nano Systems

Due to the ability of graphene to expand slightly when electrically charged, nanotubes have been found to act conveniently as actuators. Kim et al. 3.346 demonstrated it by designing nano-tweezers able to grab, manipulate, release nano-objects (the nano-bead having been handled for the demonstration was actually Fig. 3.31 Sketch explaining how the first nano-tweezers were designed. First is a glass micropipette (dark cone, top). Then two Au coatings (in grey, middle) are deposited so that they...

STM Probe Construction

The STM probe should have a cantilever integrated with a sharp metal tip with a low aspect ratio (tip length tip shank) to minimize flexural vibrations. Ideally, the tip should be atomically sharp, but in practice most tip preparation methods produce a tip with a rather ragged profile that consists of several asperities with the one closest to the surface responsible for tunneling. STM cantilevers with sharp tips are typically fabricated from metal wires of tungsten (W), platinum-iridium...

Passive Micropumps

A passive system is defined inherently as one that does not require an external energy source. Thus, the term passive micropump might seem misnomer upon initial inspection. However, there have been some efforts dedicated to realizing a passive micropump that essentially does not draw energy from an external source, but stores the required actuation energy in some form and converts it to mechanical energy on demand. Passive Micropump Based on Osmotic Pressure Nagakura et al. 9.71 have...

Solid Carbon Source Based Production Techniques for Carbon Nanotubes

Among the different SWNT production techniques, the three processes (laser ablation, solar energy, and electric arc) presented in this section have at least two common points a high temperature (1,000K < T < 6,000 K) medium and the fact that the carbon source originates from the erosion of solid graphite. In spite of these common points, both the morphologies of the carbon nanostructures and the SWNT yields can differ notably with respect to the experimental conditions. Before being...

Isbn 3540012184

Spinger-Verlag Berlin Heidelberg New York This work is subject to copyright. All rights reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September, 9, 1965, in its current version, and...

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...

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...

Promising Approach To Unimolecular Devices Relies On The Fabrication Of Nanometer-sized Gaps In Metallic Features

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...

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...

Track Following Controller Design for a MEMS Microactuator Dual Stage 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 Thin Film 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...

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...

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...

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...

If

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

Oxide Assisted Growth Nanowires

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...

Biomolecules in Therapeutic Nanodevices Self Assembly 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...

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 Source Based 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

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,...