Wafer Polishing

The final step of wafer fabrication is chemical-mechanical polishing (CMP). This method is currently employed and involves both mechanical and chemical polishing mechanisms. Its purpose is to provide a smooth, specular surface where device features can be defined by lithographic processes (see Section 4) or to improve bondability (refer to Section 3.7.10). Wafers are fixed to a hard ceramic base plate using a wax bonding method. These are then lowered against a synthetic-leather-made polishing...

Info

Rahouadj, and E. Gaffet, Ann. Chim. Sci. Mater 22, 351 (1997). 149. A. Caro and H. Van Swygenhoven, Phys. Rev. B 63, 134101 (2001). 150. P. Keblinski, D. Wolf, S. R. Phillpot, and H. Gleiter, Scripta Mater 41, 631 (1999). 151. D. Wolf, Current Opinion Solid State Mater. Sci. 5, 435 (2001). 152. H. Van Swygenhoven, D. Farkas, and A. Caro, Phys. Rev. B 62, 831 153. H. Van Swygenhoven, Science 296, 2386 (2002). 154. H. E. Schaefer, K. Reimann, W. Straub, R. Phillipp, H....

Determination of Creep Stress Relaxation and Other Attributes to Local Plasticity

Indentation experiments can also be used to study the deformation mechanisms of nanocrystalline materials. They offer convenient means to determine, for example, the strain rate sensitivity of the material. Strain rate sensitivity m is the slope of a plot of log applied stress versus log strain rate, that is, the inverse of the stress exponent n in Eq. (4). The effective strain rate eeff is obtained from where A A(xp) is projected contact area and xp is the plastic depth beneath the indenter....

Faradays Induction

According to Faraday's induction law, an electromotive force (emf) will be induced in a closed-path electrical circuit if there is a change of magnetic flux linking to the circuit. In equation form, Faraday's law is expressed as where A is the surface area, and B is the magnetic flux. The negative sign in the equation is a result of Lenz's law, which states the direction of the induced voltage is such that the induced flux opposes the incident flux. Faraday's induction law is demonstrated in...

Disordering of Ordered Alloys by Ball Milling The Example of X2MnSn Heusler Alloys

Heusler alloys X2YZ, more particularly X2MnSn alloys in which Mn atoms carry a magnetic moment of more than 3 xB, are excellent candidates for evidencing such behavior. Their structure is indeed reasonably simple (Fig. 7) and their magnetic (and hyperfine magnetic) properties are well documented (see 324-331 among others). The L21 structure may contain two types of antiphase boundaries (APBs) with fault vectors of a 4(111) (B2 APBs) and a 2(100) (L2j APBs) respectively, where a is the lattice...

Silicon Nitride

Thin films of silicon nitride are of special interest for microtechnology. These films can be used for passivating devices, because they serve as good moisture barriers, prevent sodium diffusion, and provide excellent scratch protection. The films also can be used as masks for selective oxidation of silicon (LOCOS), because silicon nitride oxidizes very slowly. Another application is the use as an etching mask for wet chemical KOH etching and the use as a construction material in microsensors...

Local Effect Microscopic Model

In a recent paper, Tian and Atzmon have studied the kinetics of microstructure evolution in nanocrystalline Fe powder during mechanical milling 86 . A phenomenological model has been proposed based on the assumption of simultaneous grain refinement and grain growth. The weak temperature dependence of the grain-growth term is consistent with nonequilibrium vacancy production. Based on the results of such an approach, it has been shown that the efficiency for refinement and vacancy production...

Physical Vapor Deposition

Rather than relying on chemical reactions to produce the reacting species to form the film as in CVD, PVD methods use mainly physical processes to deposit films. PVD is more versatile than CVD, allowing for the deposition of almost any material. PVD is done under vacuum using, either the evaporation of a solid or molten source or by using energetic gaseous ions in a plasma to knock off or sputter dislodge the atoms from a source target. These atoms or molecules then travel through a vacuum or a...

Chemical Vapor Growth

Chemical and physical vapor growth are processes where the substrate material is transformed into a layer with different properties. Within this group, thermal oxidation is of prime importance in IC technology where thermally grown field and gate oxides can provide the highest quality oxides having the lowest interface trap densities. Diffusion and ion implantation are two key processes which are used to introduce controlled amounts of dopants into semiconductors. They are used to dope...

Brillouin Scattering

A very powerful, nondestructive, and sensitive technique for the characterization of elastic properties of materials, and in particular for thin films or multilayers, but also for nanos-tructured materials, is Brillouin spectroscopy. Brillouin light scattering is the inelastic scattering of an incident optical wave field by thermally excited elastic waves (usually called acoustic phonons). Since the advent of lasers, Brillouin scattering has received considerable interest for the...

Molecular Gearing Systems

Molecular gearing systems were among the first successful examples of rotary mechanical devices engineered and synthesized using conventional chemistry. The major efforts aimed at synthesizing molecular gears have been focused on triptycene derivatives. The use of triptycenes as molecular gears started during the 1970s with a significant body of the research being done by Mislow and Iwamura 42-44 . The simplest triptycene gears, however, were constructed by Oki 45 using two triptycene...

Amorphous Float Glass Wafer Production

Float glass offers the quality of plate glass combined with the lower production cost traditionally associated with sheet glass manufacturing. Float glass is virtually distortion and defect free, making it ideal for various premium-glazing applications in buildings and homes or for automotive glass along with hundreds of other glass fabrications. Float glass manufacturing is not unlike the manufacturing of commodities like steel or plastic. Each of the processes requires raw materials to be...

With Ferromagnetic Glass Cores

Ferromagnetic glasses were widely used in the 1980s as the permeability susceptibility-changing ferromagnetic glass cores for the induction-based sensors. Since the inductance of the coil is proportional to the susceptibility of its core material, changes in the ferromagnetic glass susceptibility can be determined from the change of the coil inductance. It is also common to use a pair of excitation and sensing coils, where the excitation coil excites the ferromagnetic glass with an ac magnetic...

Physical Liquid Deposition

In physical liquid deposition, an amount of liquid is deposited (coated) first on a substrate and then it is hardened to form a solid film. Several methods exist such as dipping, spraying, painting, casting, or melting as will be treated in this section. Spinning Spin coating has been optimized for deposition of thin layers of polymer on round and nearly ideally flat surface silicon wafers. For example in photoresist spinning, the wafer is held on a vacuum spindle, and 1 cm3 of liquid resist is...

CMR Manganite Nanocomposites

In the previous section we have discussed the role of grain boundary (GB) scattering in modifying the low-field extrinsic magnetoresistance. To increase the low-field tunneling magnetoresistance in manganites, it is important to enhance the electronic barriers in the GB by controlled doping at the intergranular regions. Recently, it was reported that introduction of a second phase, usually a nonmagnetic or an anti-ferromagnetic insulator, into the ferromagnetic manganite matrix would lead to an...

Liquid Phase Film Formation

For films formed from a liquid solution, bulk properties of the film and substrate determine the step coverage of the formed layer. Important phenomena to consider are surface free energy, wettability, and viscosity and include inertia effects caused by fast rotation in a spindle as in spin coating. In general, the term planarization is used in such cases. In the ideal case, the deposited film will perfectly fill any surface irregularity and forms a flat surface as shown in Figure 48. This...

Hybrid Lithography

In order to improve resolution and keeping throughput high, sometimes write lithography is combined with print lithography. For example, the combination of imprinting with scanning probe lithography for the mold preparation may possibly provide an important breakthrough for a low-cost mass preparation of nanometer scale devices. At this point, the local oxidation of semiconductor or metal surfaces seems to offer the most reliable method to produce the required molds. It is important to note...

Se GeSe Amorphization Induced by Ball Milling

Experiments show evidence that mechanical attrition can induce complete crystallization of an amorphous solid and complete amorphization of a nanocrystalline phase as shown in the case of Se 142 . The induced MA phase transformation has been found to be closely related to the initial microstructure of the processed materials. Depending on the starting materials, MA may either (i) raise the excess energy of the milled sample by accumulating various microdefects or (ii) lower the total excess...

Reduction of Minerals The Case of Bastnaesite

A nonthermal process for extracting rare earths from bast-naesite by means of mechanochemical treatment has been developed by Zhang and Saito 302 . Bastnaesite (ReCO3F, Re rare earths) is one of the most important resources containing rare earth elements such as La and Ce. There are several hydrometallurgical methods for extracting them from bastnaesite. They can be classified into two process methodologies one is the acidic method using H2SO4 solution the other the alkali method using NaOH. In...

Rotaxanes

Several different schemes have now been reported for producing a rotaxane that undergoes shuttling action in response to an external stimulus. In 1991 one of the first functional molecular shuttles produced in reasonable yields was reported by Anelli and co-workers 11 . It is a 2 rotax-ane containing a linear dumbbell-shaped component, possessing two w-electron rich hydroquinone rings separated by a polyether chain, and terminated by two bulky triisopropy-lsilyl groups as stoppers. A cyclic...

Pic

Replaced by a conductor line carrying a voltage pulse. Experimental results show the MDL force sensor can detect a small force of 0.01 N, and the force dependency follows an exponential profile up to 0.35 N. Chiriac et al. 34 and Hristoforou et al. 18 also designed a stress and torque sensor based on the MDL. The sensor, illustrated in Figure 30, consists of a FeSiB ferromagnetic glass wire with its top end fixed and bottom end loaded with a mass or torque. An excitation coil is placed near the...

Plasticity of Nanocrystalline Materials

Plasticity of nanocrystalline materials is of interest from both theoretical and practical points of view. The practical aspects are related both to the ease of producing complicated forms by plastic deformation as well as to the service performance of these materials. As discussed in the previous section, the susceptibility of, for example, fine-grained ECA pressed materials to strain localization limits their tensile and fatigue ductility and in practice to a large extent determines their...

Tensile and Compressive Response Ductility and Creep Superplasticity

Again, the starting point in the discussion of these properties is the already well-known strong effect that grain size has on the ductility and toughness of conventional grain-size (> 1 m) materials. For example, the ductile-brittle transition temperature in conventional mild steel can be lowered by about 40 C by reducing the grain size by a factor of 5. We here recall that the brittleness can be defined in terms of the strain-rate sensitivity m, that is, the exponent in the equation and can...

Effects of Alloy Compositions on the Ferromagnetic Glass Properties

The magnetomechanical properties of ferromagnetic glasses, such as magnetostrictive and magnetoelastic coupling, magnetic hardness, hysteresis losses, and anisotropy are all dependent upon alloy composition. Although there are no general theories for predicting the effects of alloy composition on the properties of the ferromagnetic glasses, several models have been developed to describe the effects of alloy composition on Fe-rich and Co-rich ferromagnetic glasses 70 . In general, Fe-rich...

Introduction

Amorphous ferromagnetic glasses are noncrystallized ferromagnetic alloys free from defects such as grain boundaries, precipitates, or phase segregation 1, 2 . The amorphous structure of these materials gives rise to unique magnetic and mechanical properties, such as high mechanical strength 3 , large magnetoelastic coupling, large magnetostriction 4 , and the so-called giant magnetoimpedance effect (GMI) 5 , which make them suitable for various sensor applications. The large magnetostriction...

Elastic and Anelastic Properties of Nanocrystalline Materials

There are very few theoretical considerations related to the elasticity of nanocrystalline materials. Some early experimental results have prompted ideas on elastic properties being dependent on the volume fraction of lower-density grain boundary phase in relation to the bulk phase 39 . Later, however, the experimental results 40, 41 have, according to Morris 2 , quite convincingly showed that the grain size refinement does not play any obvious role in modifying Young's modulus, shear modulus,...

Gas Phase Etching

Major limitations of wet chemical etching of silicon (dioxide) with hydrofluoric acid (HF) include the necessity for a subsequent rinse and dry step after each etch step, which is critical when dealing with fragile structures. Moreover, the hydrophobic silicon surface strongly attracts particles and other bath contaminations. Another drawback is the inability of wet chemicals to penetrate small geometries with high aspect ratios due to surface tension. Moreover, as wafer size continues to...

Controlling the GMI Effect

Equations (51) and (52) show that the impedance of the ferromagnetic glasses increases with the factor M t, e for both ferromagnetic glass wires and ribbons. Hence one can increase the sensitivity of a GMI sensor by increasing the operating frequency. In addition, it is also found that the transverse and circumferential permeabilities are dependent upon the amplitude of the driving current, applied stress, and annealing temperature. The effect of ac frequency on the GMI was studied by Knobel et...

Optical Printing

Optical lithography comprises the formation of images with visible or near-UV radiation (A 300-380 nm) in a resist (e.g., Novolac) using shadow or projection printing. Shadow printing may be employed where the gap between mask and wafer is small. In case of projection printing, some sort of image-forming system (e.g., a 4 1 demagnification lens) is interposed between mask and wafer. The linewidth limit of optical printing lies near 0.4 m, although 0.2 m features may eventually be printed under...

Colossal Magnetoresistive Manganites

Recently, it has been recognized that some perovskite oxides (divalent doped lanthanum and rare-earth mangan-ites and some related oxides of Ruddlesden-Popper series 8 ) possess large negative magnetoresistance or colossal magnetoresistance (CMR). These materials undergo phase transition from the paramagnetic (PM) insulating (semiconducting) phase to the ferromagnetic (FM) metallic phase below the corresponding Curie temperature. In these per-ovskite oxides, metal-insulator transition (MIT)...

Extreme Ultraviolet Printing

To extend the ongoing technological trends to wavelengths below 100 nm, processes of a short-wavelength imaging method are explored, which includes reduction optics analogs to optical projection printing. Such a reduction scheme with the ability of making diffraction-limited images would take full advantage of the short wavelength. The method, initially called soft X-ray projection lithography but later named extreme-ultraviolet printing (EUVP with wavelength between 4 and 200 nm), uses...

MDL Stress and Torque Sensors

Hristoforou and Reilly 17 designed a simple MDL force sensor using a Metglas 2605SC ribbon. The sensor is similar to that shown in Figure 29, but with the excitation coil Figure 29. The basic arrangement of a magnetoelastic delay line. An elastic wave is generated by the excitation coil and propagated along the MDL due to the magnetostrictive effect. As the elastic wave propagates to the other end of the MDL, it causes an induction voltage at the sensing coil by the inverse magnetostrictive...

Synthesis Of Colossal Magnetoresistance Cmr Nanocomposites

Composites can be prepared in different ways. For making these composites, the insulating material chosen should be inert to the manganites in which they are inserted and insulator should also easily form nano-grade particles in the manganite matrix. Conventional methods of preparing CMR materials can also be employed for synthesizing CMR composite 27, 51 with other oxides magnetic or nonmagnetic . Magnetic nanoparticles, a widely studied material with metal oxides grain size lt 10 nm , can be...

Material Properties

Lide, Handbook of Chemistry and Physics, 74th ed. CRC Press, Boca Raton, 1994. 43. S. Timoshenko, Strength of Materials, Part I Elementary Theory and Problems, 3rd SI ed. Van Nostrand, New York, 1955. 44. J. M. Gere and S. P. Timoshenko, Mechanics of Materials, 3rd ed. Chapman amp Hall, London, 1991. 45. R. C. Hibbeler, Engineering Mechanics Mechanics of Materials, 3rd ed. Prentice Hall, New Jersey, 1997. 46. R. A. Higgins, Properties of Engineering Materials. Industrial Press, New...

Magnetization Curve

Stress Induced Magnetization Curve

As indicated in Section 2.2, the magnetic flux B and field H are scaled by the permeability similarly the magnetization M and field H are scaled by the susceptibility x. For ferro- and ferrimagnetic materials, and x are not constants instead they are nonlinear functions that depend on the previous state of magnetization hysteresis . Figure 16 is a plot of B and 0M versus H, known as the BH or MH loop, where and x are the tangents of the curve at different operating H. Note that from Figure 16,...

Ductility of Nanocrystalline Materials

The ductility of nanocrystalline materials can be examined by tensile testing. In a tensile test ductility is related to the elongation at fracture or the reduction of area at necking at fracture. A classical approach to theoretical consideration of the ductility of nanomaterials is that of Morris 2 , who uses the so-called Consid re construction to describe the respective importance of stress level and work-hardening rate in controlling the geometric instability responsible for the onset of...

References

Phys. 38, 4096 1967 . 2. S. Mader and S. Nowick, Appl. Phys. Lett. 7, 57 1965 . 3. A. Inoue, Mater. Sci. Eng. A 304-306, 1 2001 . 4. T. J. de Lacheisserie, J. Magn. Magn. Mater. 25, 251 1982 . 5. M. Knobel, J. Schoenmaker, J. P. Sinnecker, T. Sato, R. Grossinger, and W. Hofstetter, Mater. Sci. Eng. A 226-228, 546 1997 . 6. R. C. O'Handley, Modern Magnetic Materials Principles and Applications. Wiley, New York, 2000. 7. M. Brouha and J. van der Borst, J. Appl....

Instrumented Nanoindentation 411 Principle and Equipment

Conventional hardness measurement is insufficient to estimate the properties of, for example, thin nanostructured films, because of its low accuracy in the low-load indentation region that is due to limitations of the resolution of the optical systems attached to the hardness testers of conventional type. The development of the testing equipment has enabled the users to continuously monitor the load experienced by the indenter and the depth of penetration. This made it possible to overcome the...

Single Crystal Quartz Wafer Production

Quartz in some respects presents us with an even more ideal substrate material than silicon because of its nearly temperature-independent thermal expansion coefficient. A variety of quartz micromachined piezoelectric devices are on the market such as electronic filters, resonators, and wristwatch tuning forks. Natural quartz has been replaced by alpha quartz grown in large single crystals using a hydrothermal process. It is not at all like the growing of single-crystal silicon. It occurs at 350...

Microtechnology

Eijkel, A Thin-Film Magnetoresistive Angle Detector, Ph.D. Dissertation Thesis , University of Twente, Enschede, the Netherlands, 1988. 100. F. C. M. van de Pol, A Pump Based on Micro-engineering Techniques, Ph.D. Dissertation Thesis , University of Twente, Enschede, The Netherlands, 1989. 101. F. R. Blom, Resonant Silicon Beam Force Sensor, Ph.D. Dissertation Thesis , University of Twente, Enschede, The Netherlands, 1989. 102. S. Bouwstra, Resonating Microbridge Mass Flow Sensor,...

Applications

Nanostructured materials or reinforced materials including special nanostructures, as well as hard thin films or multilayers, are of course extremely interesting in view of a number of applications as structural materials or reinforcement fibers, hard protective coatings, or high-resistance components in special devices such as MEMS micro-electromechanical systems , NEMS nano-electromechanical systems , magnetic media, X-ray optical elements e.g., multilayers , etc. Metals, alloys,...

Molecular Ratchets

Ratchets are devices that allow motion in only one direction. Generally they consist of three components 1 the ratchet wheel, 2 the pawl, which acts to prevent rotation of the wheel in the wrong direction, and 3 the spring, which holds the pawl in place. Kelly et al. sought to translate these macroscopic properties of the ratchet to the molecular scale using triptycene as a wheel and helicenes as the pawl and spring components 47, 48 . The synthesis of trip-tycyl 4 helicene successfully...

Laser Induced Surface Acoustic Waves

Frequency spectra of acoustic waves can be measured either exciting the waves, by piezoelectric excitation in quantitative acoustic microscopy 60 or by laser pulses in laser acoustic methods see below 61, 62 , or exploiting the thermally excited waves, in Brillouin scattering experiments 63 . In acoustic microscopy, a piezoelectric transducer is coupled, through an acoustic lens and a contact fluid, to the specimen surface the transducer excites and detects the waves. In laser acoustic methods,...

Magnetostriction Effects

Most ferromagnetic glasses exhibit magnetostriction, a phenomenon where the dimensions of an object change when subjected to the influence of an external magnetic field. Magnetostriction is generally quantified with the saturation magnetostriction As, which is defined as the ratio of the change in length Al l at magnetic saturation. Although it is well known that the magnetostriction of a ferromagnetic glass varies with alloy composition, predicting the effects of alloy composition on the...

Solid State Reaction Method

It is observed that for preparing nanocomposite of nonmagnetic, insulating, and or glass particle in ferromagnetic manganite matrix, solid-state reaction method, with low-temperature sintering, is a useful one. The efficiency of these composites depends on how the insulating component is dispersed around the grain boundaries of the ceramic. Bulk polycrystalline La07Pb03MnO3 x wt Ag LPMO Ag x 0-20 composites have been prepared at relatively lower sintering temperature 900 C to keep the grain...

Granular Giant Magnetoresistance

Granular magnetic materials, where magnetic metallic particles are embedded in a nonmagnetic metallic host, show remarkable negative giant magnetoresistance GMR . Granular GMR was first found in Cu-Co granular systems by Berkowitz et al. and Xiao et al. in 1992 3, 4 after the discovery of GMR in Fe Cr multilayers in 1988 1 . The equilibrium solubility of Co in Cu is extremely small. But an extended solid solution can be formed in Cu-Co thin films. By thermally annealing the solid-solution...

Magnetostrictive Delay Line Sensors

Ferromagnetic glasses, in particular Fe-rich alloys, are widely used to construct magnetostrictive delay lines since they have a large magnetoelastic coupling, which allows efficient energy conversion between magnetic fields and acoustic waves. The basic arrangement of the MDL is illustrated in Figure 29 A current pulse is first sent to the excitation coil to generate an ac magnetic field, and an elastic wave is created and propagated along the MDL due to the magnetostrictive effect. As the...

Soft Magnetic Materials

Magnetically soft materials have a low coercivity and high permeability, which result from the low crystalline and strain anisotropy energies. The low anisotropy energy minimizes the domain wall energy, allowing the rotation of domain wall with minimum energy loss when subjected to an external field. Due to reversible magnetization and a correspondingly low hysteresis loss, soft magnetic materials are largely used in field sensors, power transformers, induction motors, etc. Soft magnetic...

Diamagnetism

All materials exhibit diamagnetism however, the effect of diamagnetism is small and often shadowed by other magnetic effects. A diamagnetic material has the ability to repel magnetic fields, with the flux density in diamagnetic materials actually being less than in vacuum. Classically, dia-magnetism is explained by the reduction of the electron velocity due to an external magnetic field. To understand diamagnetism, first consider an atom with an electron moving clockwise in an orbit...