Silicon Wafer

Right angle magnetron sputtering (RAMS) was used to produce hydroxyapatite (HA) film coatings on pure titanium substrates and oriented silicon wafer (Si(0 0 1)) substrates with flat surfaces as well as engineered surfaces having different forms. Analyses using synchrotron XRD, AFM, XPS, FTIR and SEM with EDS showed that as-sputtered thin coatings consist of highly crystalline hydroxyapatite. The HA coatings induced calcium phosphate precipitation when immersed in simulated body fluid, suggesting in vivo bioactive behavior. In vitro experiments, using murine osteoblasts, showed that cells rapidly adhere, spread and proliferate over the thin coating surface, while simultaneously generating strong in-plane stresses, as observed on SEM images. Human osteoblasts were seeded at a density of 2500 cells cm -2 on silicon and titanium HA coated substrates by RAMS. Uncoated glass was used as a reference substrate for further counting of cells. The highest proliferation of human osteoblasts was achieved on HA RAMS-coated titanium substrates. These experiments demonstrate that RAMS is a promising coating technique for biomedical applications.

In this work, we propose a pressure sensor fabricated on compound LiNbO 3 /Silicon/Silicon substrates obtained by Au/Au bonding at room temperature and double face lapping/polishing of LiNbO3/silicon stack and a final gold bonding with a structured silicon wafer. Sensitivity of the final sensor to bending moments then is tested and results show pressure sensitivity of such devices.

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Interface acoustic waves (IAWs) propagate along the boundary between two perfectly bonded solids. For a leakage-free IAW, all displacement fields must be evanescent along the normal to the boundary inside both solids, but leaky IAWs may also exist depending on the selected combination of materials. When at least one of the bonded solids is a piezoelectric material, the IAW can be excited by an interdigital transducer (IDT) located at the interface, provided one can fabricate the transducer and access the electrical contacts. We discuss here the fabrication and characterization of IAW resonators made by indirect bonding of lithium niobate onto silicon via an organic layer. In our fabrication process, IDTs are first patterned over the surface of a Y-cut lithium niobate wafer. A thin layer of SU-8 photo-resist is then spun over the IDTs and lithium niobate to a thickness below one micrometer. The SU-8-covered lithium niobate wafer then is bonded to a silicon wafer. The stack is subsequently cured and baked to enhance the acoustic properties of the interfacial resist. Measurements of resonators are presented, emphasizing the dependence of propagation losses on the resist properties. Comparison with theoretical computations based on periodic finite element/boundary element analysis allows for explanation of the actual operation of the device.

Ellipsometric detective method of refractive index, absorptive index and thickness of the film deposited on the substrate with some optical parameters has been developed. This method is applied for optical parameters and film thickness detecting in visible and near IR spectrum. Refraction index and film thickness dispersion has been studied. It has been determined that film refractive index (2.6 on average) is by 7% less than that of monocrystalline CdTe.

The detection and quantitative measurement of trace components is a challenging task. The key component in such an instrument is the concentration step where the analytes are accumulated before the analysis. In this research, simple and inexpensive processes for the microfabrication of microconcentrator that can be used with sensors and as an injector in GC were developed. Analytes are selectively concentrated in the microconcentrator. Rapid electrical heating of the microconcentrator releases the adsorbed species as a "concentration pulse", which serves as an injection for the detection system. The relatively small size of the microconcentrator allows it to be heated and cooled rapidly. The microconcentrator serves the dual purposes of sample concentration and injection. The devices were fabricated on 6-inch silicon substrate using standard photolithographic processes. First, a microheater embedded in silicon wafer was fabricated. The channels were lined with a conductive layer by sputtering metal film through which an electric current could be passed causing Ohmic heating. The preconcentration was done on thin-film polymeric layer deposited in the channel. Rapid heating of the conductive layer caused the "desorption pulse" to be injected into the sensor/detector. Several channel configurations were fabricated with a width between 50 to 456 [an, depth between 35 and 350 pm and length between 6 and 19 cm. The separation distance between the channels was varied such that the entire microheater fitted in a 1 cm2 area. Due to their small size, the microconcentrators could be fabricated more than 50 at a time on a 6-inch silicon wafer. In the first part of this research, the heating characteristics of the microheaters are studied. Deposition of metals to form a resistive heating element in microchannels was demonstrated. It was found that temperature as high as 360°C could be attained in a ten seconds. The microconcentrator was effective as a concentrator plus injector. It exhibited high signal enhancement and precision.

The pn camera of EPIC is inherently robust against radiation damage effects. Nevertheless, the knowledge of charge transfer inefficiency (CTI) of the pn camera is crucial for obtaining the correct energy scale. We describe detailed in-orbit monitoring of this effect, utilizing the internal calibration source. We find that during the first two years in orbit the CTI increased by ∼ 4% for Al-K α and by ∼ 7% for Mn-K α . The increases in the CTI are well within expectations, with no measurable effect on the energy resolution.

One of the three imaging spectroscopic cameras abord XMM will be equipped with a pn-CCD. The chip exhibits features that make it ideally suited for the XMM mission. Due to its layout, quantum e ciency is very good, especially at very low and very high X-ray energies. Parallel signal preampli cation makes fast readout possible, resulting in high time resolution of 70 ms for Full Frame readout or even a few s for the timing mode, where only part of the CCD is read out. Radiation hardness has been tested and proven to be excellent. The Flight Model camera has been calibrated at various test sites. An overview over the achieved performance is given in the following text.

An analytical model is proposed which relates the bonding temperature, pressure, and duration with the integrity of metal-metal thermocompression bonds. Unlike previous models, this approach takes into account the pressure-dependent time evolution of the thermocompression bond formation. The model allows calculation of the true contact area of rough surfaces, based on a creep-dominated plastic deformation. Verification of the model was provided through experiments on Cu-Cu thermocompression bonds of electroplated Cu on diced silicon wafers with chemical-mechanical polished surfaces. The samples were bonded at a range of temperatures, pressures, and times. Shear strength measurements were used to characterize the effects of the bonding parameters on the interface bond strength. Calculated true contact area and bond shear strength can be related by a single proportionality factor. The model can be used to predict the thermocompression bond quality for given bonding parameters and process optimization for reliable bonds, thus assisting in the adoption of the Cu thermocompression bond process in the three-dimensional integrated circuits applications.

Self-diffusion coefficients of Si in thermally grown SiO2 on a semiconductor-grade silicon wafer have been determined at temperatures between 1150 and 1300 °C under equilibrium conditions using isotope heterostructures (natSiO2/28SiO2). Si self-diffusion was induced by appropriate heat treatments, and the diffusion depth profiles of Si30 isotope from SiO2nat to SiO228 layers were determined by secondary ion mass spectrometry (SIMS). The diffusion coefficients found in the present study for 1150–1300 °C are more than two orders of magnitude smaller than the values measured with semiconductor-grade SiO2 in the presence of excess silicon, i.e., in nonequilibrium conditions, and agree very well with previously reported values of Si self-diffusion in fused silica under equilibrium conditions.

The possible benefits of phosphorus gettering as applied to production multicrystalline silicon wafers have been evaluated. After optimization of an open tube POCl 3 process, relatively low temperatures and short times have been found to significantly improve the minority carrier lifetime of most wafers. The possible gettering action stemming from the industrial process of phosphorus diffusion has also been investigated and found to be similarly effective. Average lifetimes of 45µs (diffusion length of 360µm) were obtained, with some wafers reaching maximum values up to 130µs. Lifetime monitoring of a commercial cell fabrication line has also enabled characterization of the voltage limits imposed by the standard emitter and aluminum back-surface-field. The results indicate that the bulk, as improved by emitter gettering, is generally not the limiting factor on cell performance.

This paper describes the 3D simulation and measurements of free space characterization for the complex permittivity of p-type and n-type doped silicon wafers at K-Band. The component of this free space measurement system (FSMM) consists of Millitech series GOA Gaussian optics lens antennas, Vector Network Analyzer (VNA) and a high performance workstation. The antennas were modeled and simulated using Computer Simulation Technology (CST) software. The thru, reflect and line (TRL) calibration technique were used to eliminate the effect of undesirable multiple reflections. The simulation and measurement results are presented where good agreements are observed.

In this paper, we use Random Forests to learn the inverse lithography function. We choose a suitable feature vector based on the structure of the lithography transfer function and use an ensemble of decision trees as the classifier. While our method yields outputs comparable (in visual quality as well as BER) to previous work, it is 10 folds faster.

Le procédé thermique rapide (RTP : Rapid Thermal Process) est très utilisé dans la fabrication des composants de microélectronique. Il correspond à plusieurs étapes clés comme les recuits d'implantation, de siliciuration, d'oxydation, de nitruration et le dépôt de couches minces par CVD (Chemical Vapor Deposition). Il consiste à chauffer un nombre restreint de substrats de silicium par des lampes infrarouges permettant ainsi des durées de traitement très courtes. L'enjeu majeur est d'obtenir une température uniforme à la surface du substrat. Le but de cette étude est de mieux comprendre les relations entre le chauffage par les lampes infrarouges et le profil de température d'un substrat de silicium dans un système thermique rapide, le système AS-One 150, en vue d'améliorer l'uniformité de la température du substrat de silicium. La modélisation du système est réalisée en deux et trois dimensions. La modélisation approfondie d'une lampe infrarouge est aussi effectuée pour mieux cerner les paramètres des lampes à entrer dans les modèles en deux et trois dimensions. Les modélisations ont été réalisées à l'aide du logiciel CFD'ACE. Les équations de conservation de la masse et de la chaleur ont été considérées et l'équation de transfert radiatif est résolue selon un schéma utilisant la méthode Monte-Carlo. Les modèles sont validés en confrontant les profils de température du substrat et les températures des filaments à des mesures expérimentales. Des simulations avec le modèle en deux dimensions sont par la suite réalisées pour mettre en évidence l'influence du hublot en quartz sur le profil de température du substrat et inversement. Différents paramètres du modèle sont modifiés comme les propriétés radiatives du substrat et du hublot ou la diffusivité. Cette corrélation est ensuite expliquée par les propriétés d'émission, d'absorption, de réflexion et de transmission du substrat de silicium et du hublot en quartz et par l'influence des parois froides du réacteur à 300 K. Les différents phénomènes expliquant la forme du profil de température du substrat sont alors posés dans un schéma en quatre phases. La discussion de ce schéma permet d'aboutir à deux idées pour améliorer l'uniformité de la température du substrat. Ces dernières consistent à modifier les propriétés radiatives au niveau de la surface inférieure du hublot pour laisser passer le rayonnement des lampes et éviter l'absorption du rayonnement émis par le substrat de silicium selon deux configurations. Ces idées sont alors vérifiées par des simulations numériques en deux dimensions. Une future mise en oeuvre expérimentale est finalement envisagée.

An analytical model is proposed which relates the bonding temperature, pressure, and duration with the integrity of metal-metal thermocompression bonds. Unlike previous models, this approach takes into account the pressure-dependent time evolution of the thermocompression bond formation. The model allows calculation of the true contact area of rough surfaces, based on a creep-dominated plastic deformation. Verification of the model was provided through experiments on Cu-Cu thermocompression bonds of electroplated Cu on diced silicon wafers with chemical-mechanical polished surfaces. The samples were bonded at a range of temperatures, pressures, and times. Shear strength measurements were used to characterize the effects of the bonding parameters on the interface bond strength. Calculated true contact area and bond shear strength can be related by a single proportionality factor. The model can be used to predict the thermocompression bond quality for given bonding parameters and process optimization for reliable bonds, thus assisting in the adoption of the Cu thermocompression bond process in the three-dimensional integrated circuits applications.

Single-Molecular Wire Transistor Based on Carbon-Bridged Oligo-Phenylene Vinylene 1 東京工業大学フロンティア材料研究所, 2 東京大学理学研究科化学専攻, 3 神奈川大学理学部 居藤 悠馬 1, Chun Ouyang 1, 橋本康平 ,辻 勇人 ,中村 栄一 2, 真島 豊 1 1Laboratory for Materials and Structures, Tokyo Institute of Technology, 2Department of Chemistry, School of Science, The University of Tokyo, 3Faculty of Science, Kanagawa University Yuma Ito1, Chun Ouyang1, Kouhei Hashimoto2, Hayato Tsuji3, Eiichi Nakamura2 and Yutaka Majima1 E-mail: ito@nanoele.msl.titech.ac.jp

This paper presents a microassembly method for low-profile three-dimensional probe arrays for neural prosthesis and neuroscience applications. A silicon (Si) lead transfer structure, Si interposer, is employed to form electrical connections between two orthogonal planes-the two dimensional probes and the dummy application-specific integrated circuit (ASIC) chip. In order to hold the probe array and facilitate the alignment of probes during assembly, a Si platform is designed to have through-substrate slots for the insertion of probes and cavities for holding the Si interposers. The electrical interconnections between the probes and the dummy ASIC chip are formed by solder reflow, resulting in greatly improved throughput in the proposed assembly method. Moreover, since the backbone of the probe can be embedded inside the cavity of the Si platform, the profile of the probe array above the cortical surface can be controlled within 750 μm. This low-profile allows the probe array not to touch the skull after it is implanted on the brain. The impedance of the assembled probe is also measured and discussed.

X-ray and neutron reflectivity are used to study the morphology of a triblock copolymer of d-poly(styrene) and poly(2-vinylpyridine) in the form P2VP30-dPS50-P2VP~O deposited as a film on a silicon wafer. Microphase separation leads to a lamellar film which is strongly quantized in layers of about 300 A each and with P2VP at the silicon substrate. The confinement of the polymer ends to the same plane leads for the top layer to a « looping » of the polymer, so that the middle PS part can still wet the air interface completely.

Nearly monodisperse iron nanoclusters have been used to define the diameters of carbon nanotubes grown by chemical vapor deposition (CVD). Iron nanoparticles with average diameters of 3, 9, and 13 nm were used to grow carbon nanotubes with average diameters of 3, 7, and 12 nm, respectively. Transmission electron microscopy studies of the nanotubes show that the as-grown nanotubes are single-walled carbon nanotubes (SWNTs) or thin multiwalled carbon nanotubes (MWNTs) with 2 or 3 layers. Investigations of the growth conditions also demonstrate that the supply of carbon reactant is critical for enabling the growth of large diameter nanotubes from large iron nanoclusters, and that the growth temperature is especially important for achieving high-quality large diameter nanotubes. The implications of these results and possible applications of the nanotubes are discussed.

Turbulent flow drag reduction on hybrid riblet superhydrophobic surfaces 1 JULIE CROCKETT, RICHARD PERKINS, DANIEL MAYNES, Brigham Young University -We investigate characteristics of turbulent flow in a mini-scale channel where one of the walls is structured with riblets, superhydrophobic microribs, or a hybrid surface that has both structure types present. Individually, large scale riblets, approximately 80 microns tall with 160 micron spacing, provide drag reduction through damping spanwise turbulent motions, and superhydrophobic surfaces, with nearly an order of magnitude smaller features, provide drag reduction through apparent slip at the wall. It is postulated that the combination of the structures will yield a more significant drag reduction than either alone. Experiments were conducted in a rectangular channel with one wall comprised of superhydrophobic features, riblets, or the combination of the two and for channel Reynolds numbers ranging from 4500 to 20000. The velocity profile, turbulent statistics, and shear stress profile are observed using PIV measurements. In addition friction factor and turbulence production are extracted from the PIV data. Modest drag reductions were observed for both the superhydrophobic and riblet surfaces. The combined surfaces showed the greatest drag reduction and turbulence production was significantly reduced for these surfaces.

High hardness diamond-like carbon (DLC) films with good adhesion can be prepared by plasma source ion implantation in combination with radio frequency glow discharge plasma. Acetylene gas was used as the source gas to deposit the DLC films. Either pulses of -18 kV with a repetition rate of 1 kHz or DC voltages from -0.5 to -3 kV were applied to the substrate holder. A radio frequency (RF) of 13.56 MHz was applied to a counter electrode to generate a glow discharge plasma. The films were deposited on austenitic type stainless steel SUS304 as well as silicon wafers and characterized regarding thickness and surface morphology by cross-sectional SEM and by AFM, respectively. The chemical structure was investigated by Raman spectroscopy. The hardness of the films was evaluated by an indentation method. Furthermore, a ball-on-disc test was employed to obtain information about the frictional properties and sliding wear resistance of the films. The deposition rates of the films were enhanced by the RF discharge. The I D /I G value varied, depending on the deposition condition, in the range of 0.49 to 2.0. The hardness of the DLC films was around 19 GPa for the film deposited without RF and up to 26 GPa for the films deposited with RF discharge. A low friction coefficient was derived for all films prepared in this study, with lowest values of 0.04.

A plasma source ion implantation (PSII) method for the deposition of metal-containing diamond-like carbon (DLC) films on the interior surface of tubes was developed. A magnetron sputter source equipped with a Ti target was used as a plasma source and a metal source. Argon/acetylene-mixed gas was used as the working gas for plasma. A negative high-voltage pulse (-10 kV, 100 Hz, 100 s) superposed on a DC voltage of -0.5 kV was applied to the substrate tube. The chemical composition and microstructure of these films were characterized by Auger electron spectroscopy, X-ray photoelectron spectroscopy, Xray diffractometory, high-resolution transmission electron microscopy and micro-Raman spectroscopy. Uniformity in the thickness of deposited DLC films was confirmed and the structures of Ti-containing DLC films were examined.

We report on HfO2/Al/HfO2 multilayer thin films for heat mirror applications prepared on corning glass substrates by electron beam evaporation. Films fabricated at a substrate temperature of 100 °C show nano-polycrystals of HfO2 embedded in a disordered lattice according to X-ray diffraction results. Atomic force microscopy revealed that HfO2/Al/HfO2 layers possess smooth surface that is appropriate for optical heat mirror applications. Study of optical properties by UV-Visible spectrophotometer demonstrated that transmittance of HfO2/Al/HfO2 device was decreasing from UV to VIS and then slightly increasing in the NIR regions, with an opposite trend followed by reflectance. Optical constants i.e. refractive index, extinction coefficient, band gap energy, Urbach energy has also been calculated. The optical band gap and Urbach energy are found to be 4.34 eV and 3.164 eV, respectively. The collective oscillation energy loss for heat mirrors applications are also observed.

There is currently much interest in n-type base solar cells because of potential advantages, both of silicon base material and of cell process, for high efficiency. We present results of n-base solar cells on large area multicrystalline and monocrystalline silicon wafers, produced using simultaneous diffusion of phosphorus back surface field and boron emitter, screen-printed metallization and firing through. The cell process leads to record high efficiencies of 16.4% on multicrystalline and 18.3% on monocrystalline wafers. It is experimentally demonstrated that in multi-crystalline Si a low resistivity is correlated to reduced cell efficiency, with the optimum base resistivity lying between 1.5 and 4 Ωcm. By characterizing and modeling cells from monocrystalline Si, from nominally clean multicrystalline Si, as well as from intentionally Fe-contaminated multicrystalline Si, the impact of purity on emitter recombination is investigated in more detail.

A simplified laboratory process with one photolithographic step for front junction solar cells on ntype multicrystalline (mc) silicon has been developed. The emitter diffusion is done in an open tube furnace with BBr3 and back-surface-field diffusion using POCl3, loading the wafers front-to-front and back-to-back respectively and thus avoiding additional etching steps. The front surface has been passivated by a 10 nm thermal oxide grown in a tube furnace. With this simple process, efficiencies of 11.0% on n-type mc-Si and 11.5% on n-type Cz-Si have been realized without antireflection coating and without surface texture. Applying a double layer antireflection coating (DARC) on these cells, efficiencies of 16.4% on Cz-Si and 14.7% on mc-Si have been achieved.

Tip-tilt mirrors are the key components in a wide variety of systems which find applications in diverse fields such as defence, laser communication, astronomy, material processing, medical diagnostics and various research and development projects. Tip-tilt mirrors perform a variety of functions that include scanning, beam pointing and tracking, beam stabilization 1-5 and so on. In the directed energy weapon (DEW) systems, besides beam pointing and tracking, TTMs are used to correct beam jitter inherently present in high power lasers or the one introduced by the atmospheric turbulence. Most high power lasers used for DEW applications suffer from wavefront distortions in their beam profiles. A high power gas dynamic laser (GDL) involves large mass flow rate of gases expanding through short throat, short length nozzles into the cavity to achieve laser action with required power level. Non-laminar flow of gases in the laser cavity brings inhomogeneities in lasing medium resulting in degradation of wavefront quality of output laser beam. Moreover, mechanical and acoustical vibrations of the optical components and the platform supporting these components generate high frequency beam jitter. An adaptive optical system is, in general, used to correct the localized wavefront errors and the beam drift/ jitter . Wavefront errors are compensated using a segmented or continuous face-sheet deformable mirror while the beam jitter is corrected with a tip-tilt mirror . The global tilt error (jitter) correction can also be accomplished with a deformable mirror but its use drastically reduces overall bandwidth of the adaptive optical system. Most adaptive optical systems, therefore, use a separate tip-tilt mirror for correction of beam jitter. In this paper, authors described a large aperture, tip-tilt mirror assembly for correction of beam jitter in a CO 2 gas dynamic laser. Simulation studies have been carried out to optimize various response parameters of the TTM. Dynamics of TTM have been studied experimentally and results are presented. The TTM assembly has been used to correct tilt error up to ±200 micro-radians with a closed loop bandwidth of 20 Hz. A Mirror is the key component of any TTM assembly. Controlled angular displacements of the mirror along two orthogonal directions are responsible for closed loop correction of beam jitter. Clear aperture of the mirror, maximum tilt range and first mechanical resonance (open loop bandwidth) are some of the important considerations in the design of a tip-tilt mirror. Clear aperture of the mirror is governed by initial beam size of the laser source, inherent tilt errors, beam divergence and the distance of tip-tilt mirror from laser exit plane. For our application, where laser beam has an annular shape (150 mm x 88 mm), the required clear aperture of the mirror is 170 mm. For mirror substrate of this size, maintaining surface flatness over the entire aperture is a real challenge. For reasonable surface flatness of the mirror, thickness to diameter ratio must be at least 1/10. However, thick mirror substrates adversely affect closed loop bandwidth requirements of TTMs. A design tradeoff is required between these two conflicting parameters. The selection of material for the mirror substrate is another important factor which decides crucial parameters of TTM such as its first mechanical resonance, surface flatness, machinability, and capability to withstand high thermal loads. Copper, Aluminum,

Micro Electromechanical System (MEMS) microshutter arrays are being developed at NASA Goddard Space Flight Center for use as a field selector of the Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST). The microshutter arrays are designed for the spontaneous selection of a large number of objects in the sky and the transmission of light to the NIRSpec detector with high contrast. The JWST environment requires cryogenic operation at 35K. Microshutter arrays are fabricated out of silicon-on-insulator (SOI) silicon wafers. Arrays are closepacked silicon nitride membranes with a pixel size of 100x200 m. Individual shutters are patterned with a torsion flexure permitting shutters to open 90 degrees with a minimized mechanical stress concentration. Light shields are processed for blocking light from gaps between shutters and frames. The mechanical shutter arrays are fabricated using MEMS technologies. The processing includes multi-layer metal depositions, the patterning of magnetic stripes and shutter electrodes, a reactive ion etching (RIE) to form shutters out of the nitride membrane, an anisotropic back-etch for wafer thinning, followed by a deep RIE (DRIE) back-etch to form mechanical supporting grids and release shutters from the silicon substrate. An additional metal deposition is used to form back electrodes. Shutters are actuated by a magnetic force and latched using an electrostatic force. Optical tests, addressing tests, and life tests are conducted to evaluate the performance and the reliability of microshutter arrays.

Using aluminum oxide (Al2O3) films deposited by high-rate spatial atomic layer deposition (ALD), we achieve very low surface recombination velocities of 6.5 cm/s on p-type and 8.1 cm/s on n-type crystalline silicon wafers. Using spatially separated reaction zones instead of the conventional time-sequenced precursor dosing enables growth rates up to 70 nm/min, whereas conventional ALD limits the growth rate to <2 nm/min. The excellent passivation level is predominantly assigned to a high negative fixed charge density of Qf=−(4±1)×1012 cm−2 in the Al2O3 films. We demonstrate an excellent thermal stability of the passivation quality.

TiN thin films 0.095 m were deposited on silicon wafers at 800ЊC by rapid thermal low-pressure chemical vapor deposition from a TiCl q NH q H gaseous mixture. Micro-scratches were performed using a system equipped with an optical microscope, 4 3 2 an acoustic emission sensor and a friction force sensor. Critical loads were determined to evaluate the adhesion of TiN to the substrate. The influence of the indenter state on the critical load was studied. Scanning electron micrographs, electron probe microanalyses and chemical etching of the film were performed to identify and interpret the damage mechanisms. Experimental results were analyzed using the Weibull statistic. It was shown that small particles of TiN were chipped off and formed a third body, which modified the indenter᎐film contact and contributed to an increase in the range of the critical load. Models previously proposed in the literature, which allow calculation of the work of adhesion from a critical load, are discussed with respect to the damage mechanisms observed.

We fabricated and characterized on-chip Fabry-Pérot (FP) vapor sensors for the development of oncolumn micro-gas chromatography (GC) detectors. The FP sensors were made by coating a thin layer of polymer on a silicon wafer. The air-polymer and polymer-silicon interfaces form an FP cavity, whose resonance wavelengths change in response to the vapor absorption/desorption, thus allowing for rapid detection and quantification of vapors. For proof-of-concept, two polymers (PDMS and SU-8) were used independently and placed in an array in a microfluidic channel, and showed different sensitivities for different vapors. A sub-nano-gram detection limit and sub-second response time were achieved, representing orders of magnitude improvement over those previously reported. This on-chip design will enable the unprecedented integration of optical vapor sensors with GC systems.

We report on ultra low energy implant dose and activation monitoring with junctions down to 10nm using new metrology techniques and equipment. Dopant electrical activation was determined by non-penetrating elastic material probe in either a single probe configuration for CV surface electrically active dopant measurement called Nsurf or 4point probe (4PP) configuration for sheet resistance (Rs) measurements. Use of x-ray photoelectron spectroscopy (XPS) was demonstrated for implanter monitoring applications by means of surface atomic compositional mapping of the implanted As, P, or B and co-implanted species such as Ge and F as well as other elements, all independently in a single measurement. As-implanted dopant variation appears to track with surface oxide thickness uniformity measured by XPS maps.

Si resonant interband tunnel diodes that demonstrate negative differential resistance at room temperature, with peak-to-valley current ratios greater than 2, are presented. The structures were grown using low-temperature ͑320 °C͒ molecular-beam epitaxy followed by a postgrowth anneal. After a 650 °C, 1 min rapid thermal anneal, the average peak-to-valley current ratio was 2.05 for a set of seven adjacent diodes. The atomic distribution profiles of the as-grown and annealed structures were obtained by secondary ion mass spectrometry. Based on these measurements, the band structure was modeled and current-voltage trends were predicted. These diodes are compatible with transistor integration.

Full-band simulations of indirect, phonon assisted, interband tunneling are used to calculate the current–voltage response of a low-temperature molecular-beam-epitaxy-grown silicon tunnel diode with delta-doped contacts. Electron confinement in the contacts results in weak structure in the current–voltage characteristic. The structure is lost when finite lifetime effects are included. The approach uses the nonequilibrium Green function formalism in a second-neighbor sp3s* planar orbital basis.

Boron carbide (B 4 C) is one of the few materials that is expected to be most resilient with respect to the extremely high brilliance of the photon beam generated by free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at light source facilities, B 4 C-coated optics are subject to ubiquitous carbon contaminations. These carbon contaminations represent a serious issue for the operation of high performance FEL beamlines due to severe reduction of photon flux, beam coherence, creation of destructive interference, and scattering losses. A variety of B 4 C cleaning technologies were developed at different laboratories with varying success. We present a study regarding the lowpressure RF plasma cleaning of carbon contaminated B 4 C test samples via inductively coupled O 2 /Ar, H 2 /Ar, and pure O 2 RF plasma produced following previous studies using the same ibss GV10x downstream plasma source. Results regarding the chemistry, morphology as well as other aspects of the B 4 C optical coating before and after the plasma cleaning are reported. We conclude from these comparative plasma processes that pure O 2 feedstock plasma only exhibits the required chemical selectivity for maintaining the integrity of the B 4 C optical coating.

This paper presents a thermally isolated ovenized design of MEMS resonator. Ovenization (joule heating) is done to compensate for the temperature dependence of resonator frequency. An ovenized resonator has a stable frequency over a wide temperature range of -40°C to 85°C. However, the ovenized designs lead to power consumption because of joule heating. It is therefore necessary to thermally isolate the device in order to reduce the power consumption. In this paper, we demonstrate an in-chip thermal isolation and heat delivery within the device layer of the silicon resonator that reduces the power requirement without compromising on the overall performance of the device. A power consumption of 12mW for an ovenized MEMS resonator, built within a wafer-scale encapsulation process, is reported here.

Ta 2 O 5 waveguides offer great potential for high-density active photonic crystal circuits and their combination with rare-earth dopants for active devices is of interest for increasing their potential functionality. To this end, neodymium-doped Ta2O5 rib waveguide lasers have been fabricated on an oxidized silicon wafer by rf sputtering and argon ion-beam milling and laser action in this material has been demonstrated. Lasing was observed at wavelenghts between 1060 and 1080 nm and an absorbed pump power threshold of 87 mW was obtained.

In this paper, nanobeam cavity studies were performed on low-symmetric 1D photonic crystals. An eligible comparison between low-symmetric structure and a regular cavity is held. Due to nature of the resonance, reduced symmetry is expected to decrease confined resonance field; however, authors focused on the tuning of the extra parameters arisen from degenerated symmetry and promising results are obtained. Quality factor enhancement with respect to varying structural parameters is observed. To the best of authors' knowledge, this is the first time that the cavity is enhanced with controlled low symmetric structures. Also, mode profile variation and spectral response shift due to structural parameters are analyzed. Results hold potential for further integrated photonic device research such as filtering, optical memory units, quantum cryptology.

Laser induced breakdown plasmas are ``dirty'' events yielding a mixture of ionized species, electrons, and non-ionized matter of various size. Molecular emissions have been detected in excited nanosecond plasmas microseconds after the ablation event. However, with these ...

The implantation of high-density polyethylene (HDPE) has been conducted using Ag+ ions with energy of 60 keV, achieved fluences 1.5 and 10?1015 ions/cm2. Transmission electron microscopy (STEM) and field emission gun - scanning electron microscopy (FEG-SEM) showed the existence of nanoparticle clusters. X ray photoelectron spectroscopy (XPS) revealed the presence of silver in the sample surface region. The surface topography was studied by atomic force microscopy (AFM), while the surface composition uniformity was analyzed using phase imaging AFM. Optical characterization obtained by spectroscopic ellipsometry (SE) showed changes in refractive index, extinction coefficient and the optical band gap with the fluence of implanted ions.

Very little is known about the structure of organic molecular thin films at their rest potential. Further, it is not known whether the structure of these films is modified by an applied potential. We present a new x-ray scattering technique, which allows high-resolution structural studies of buried self-assembled monolayers (SAMs) that are sandwiched between silicon and mercury junctions. The high-energy x-ray beams, utilized in the present studies (32 keV), penetrate through the conducting silicon electrode. The x-ray reflectivity interference pattern thus provides information on the thickness and orientation of the molecules in the electronic junction. Our results, for alkane-thiol and alkane-silane layers, show that the SAMs form homogenous densely packed monolayers within the deeply buried interface. The thickness of these layers is compared with the SAMs prepared at the vapor/vacuum interfaces on mercury and silicon.

In this study, we embark on a deep dive into the fascinating realm of laminar axial flow around a corner. Our investigation unfolds along two key axes: to scrutinize the intricate interplay between fluid dynamics and corner geometry, and to meticulously examine the impact of different boundary conditions (BCs) imposed at the fluid-solid interface. We delve into two distinct BC scenarios: the "strict" no-slip condition [1,2,4], which dictates a stringent constraint of zero velocity at the solid surface, and the more "permissive" Navier's slip condition [2,3,5], which accommodates a degree of fluid slippage along the boundary. Of particular interest is the delicate transition between these two scales of boundary behavior. Actualized by examples we show how a short distance theory smoothly becomes an effective at larger distances. Remarkably, we unveil a profound analogy between the flow problem under investigation and the realm of stationary heat exchange. The heat exchange problem is one example of the possible application of our new method (combination of permitting BC and corner geometry) by use of one-one correspondence with a vast verity of natural problems , far beyond the confines of fluid dynamics.

In this paper, we investigate the surface properties of a series of copolymers of perfluoroalkyl methacrylate (CH2dC(CH3)COOCH2CnF2n+1, n ) 1, 6, or 10) and methyl methacrylate (MMA) and of blends of perfluorooctyl-end-capped poly(methyl methacrylate) (PMMA) and pure PMMA. The introduction of perfluoroalkyl groups significantly lowers the polymer surface energy as determined by the acid-base approach. X-ray photoelectron spectroscopy (XPS) confirms a higher fluorine concentration in the surface region (the outer 3.8 nm) as compared to in the bulk. The fluorine density in the outermost atomic layer is quantitatively determined by low-energy ion scattering (LEIS). A linear relationship is found between the fluorine density in the outermost atomic layer and the surface energy of the partially fluorinated polymethacrylates, irrespective of the length of the perfluoroalkyl chain. This linearity confirms Langmuir's "principle of independent surface action". Deviation from this linear relationship exists for both highly and sparsely fluorinated polymethacrylates and can be ascribed to the local (surface) ordering of the fluorinated tails and MMA units, respectively. This study may offer one further step toward a deeper understanding of the correlations between macroscopic surface properties and microscopic surface chemical composition.

A thermally stable copolymer of a polyimide and a dianiline terminated polydimethylsiloxane has been developed for use as a structural oxygen etch barrier material in high performance multilayer electronic wiring structures. We report on the preparation of the etch barrier material and on investigations of the etch stop and adhesion properties of this material. Studies on the effects of adhesion-promoting plasma treatments are supported by x-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS) data. Before plasma treatment, it is observed that the siloxane component segregates to the surface. After either an O2 reactive ion etch treatment or H2O plasma exposure, the unusual XPS charging effects are interpreted as a surface layer containing two distinct phases: the etched polyimide fraction and a partial overlayer of a carbon containing SiO2

Molecular dynamics (MD) simulation has become an indispensable tool in the research and development of semiconductor nanomaterials, playing a crucial role in modern semiconductor fabrication technologies. This approach not only enables the op timization of semiconductor materials but also offers in-depth insights into their fundamental atomic-scale properties, thereby enhancing the performance and reliability of semiconductor devices. In the current landscape of the semiconductor industry, where demands for quality a nd performance continue to rise, MD simulations serve as a critical method for designing, optimizing, and refining material processing techn iques. This review presents a comprehensive analysis of state-of-the-art MD simulation methods applied in semiconductor nanomaterial fabrication, with a particular emphasis on mechanical mechanisms and microstructural [1] transformations during processing. Advanced techniques such as surface machining, ion implantation, laser processing, and vibration-assisted machining can be effectively optimized using MD simulations, which help elucidate the mechanical, thermodynamic, and microstructural changes involved in these processes. Despite its adva ntages, MD simulation faces several challenges, including the calibration of interatomic potentials, accurate prediction of chemical rea ctions under extreme processing conditions, and the simulation of complex nanoscale systems. To overcome these limitations, this study also explor es recent advances, such as the integration of MD with emerging computational techniques like machine learning, to improve accuracy and predictive capability. The paper concludes by outlining future research directions, highlighting the continuous evolution of MD simulati on and its potential integration with advanced technologies such as multiscale modeling and quantum-classical hybrid simulations, aiming to further enhance semiconductor manufacturing and expand the application of these materials in high-tech industries, ultimately contributing to the ongoing innovation in the global semiconductor field.

Anodic niobia has been considered as a potential substitute for anodic tantala in the capacitor industry with advantages of increased dielectric constant (~ 40-50), and reduced oxide density (4.74 g cm -3), compared with the corresponding values for tantalum oxide, (25-30) and 8.04 g cm -3 respectively). Low leakage current values and thermal stability under polarization are mandatory for use of anodic film as a dielectric. This is the case for anodic oxides on aluminium and tantalum but not for those on niobium. The behaviour of niobium oxide can be related to the reduced band-gap energy compared with anodic alumina or tantala, higher non-stoichiometry, giving a material with n-type semiconductor characteristics, and higher tendency to crystallize under electric field. Sputtering-deposited alloys of valve metals, with particular emphasis on aluminium alloys, enable formation of anodic oxide layers of controlled composition, with the anodizing behaviour related to the contributions ...

A new technique to control selectivity of mask materials during XeF2 etching was proposed. By exposing Si sample with SiO2 and Si3N4 as mask materials to UV light of 981mW/cm2 during XeF2 etching, the etching rate ratios of Si/SiO2 and Si/Si3N4 were dramatically decreased from 11446 to 906.1 and from 488.2 to 29.3, respectively. This new technique allows us to remove the mask material selectively and change the mask pattern by UV light exposure during in-situ etching process without additional photolithography step and opens a new silicon micromachining process for 3-dimensional fabrication. The multi-step Si structure was successfully realized by this technique.