Small Wire Research Articles

Dual ICP Si Etching and Vapor Deposition Polymerization Liner for Backside Via-Last TSV Packaging Process Integration

Smart ICT (Information and Communication Technology) such as “Big Data”, “Cloud computing” and Smart Functionalities such as Stand-alone Self-activating MEMS/Sensors construct Smart Systems which enable IoT (Internet of Things), IoE (Internet of Everything) thus Smart Society. To realize above-mentioned Smart Technologies, high-density, low-power consumption, wide-bandwidth, fast-operation semiconductor devices as well as smart functional devices enabled by integrating functionalities with advanced semiconductor technologies including CMOS technologies are necessary. High-density Packaging technologies such as 3D, 2.5D packaging scheme basing on TSV (through-Si via) technology and 2.1D PCB packaging are among key technologies to satisfy the requirements from the both smart semiconductor devices and smart functional devices. "Hetero 3D stacked" technologies are gathering the most attention from now on. These technologies can make a high density packaging interconnection by using TSV on the each function devises. Heterogynous 3D Si integration has great advantages over conventional 2D devices such as high packaging density, small wire length, high-speed operation, low power consumption, and high feasibility for parallel processing. But, the radical problem about the cost of TSV fabrication is not still solved. In particular, the management of barrier metal film deposition on the smooth surface is most important technology for Cu diffuse protection [1]. On the other hand, TSV isolation liner materials with high step coverage and lower temperature deposition on the smooth surface for high frequency devices will be necessary in the future. “Scallop-free” etching process has developed for TSV fabrication [2]. In this paper, our high-density packaging technologies including scallop-free, low-temperature processed TSV solution for via-last packaging scheme and 2.1D packaging solutions on large panel build-up board by semiconductor manufacturer tools will be introduced. Especially, backside Via-last TSV process integration was proposed by “A Novel Dual ICP Plasma” Si etching and low-temperature "Vapor Deposition Polymerization (VDP)" liner (< 200 degree ) for lower-cost and low-stress hetero 3D chip stacked. “A Novel Dual ICP Plasma” is using 2 RF modes mixed ICP plasma. One is high frequency RF mode. And, another is low frequency RF mode. This plasma is able to generate high-density plasma (High etch rate), and also “Scallop-free” smooth etching. This is a kind of “Non-Bosch” process. On the other hand, this dual ICP plasma can carry out “Bosch” process at the same module. This system is very unique etching tool that can use for distinguishing between "Bosch" and "non-Bosch" to TSV cost reduction.

A New Approximate Closed Solution for Small Dipole Antenna with Method of Moments

In this paper, an approximate closed-form solution of the impedance coefficient for a small dipole using the method of moments is developed from the reduced or approximate Pocklington equation. As an application, the close-form self-impedance coefficient using the piecewise constant and linear basis functions are found, with well-defined rounding error functions. The authors found that the self-impedance using the piecewise constant basis function is inconsistent with the physics of the problem for segments close to wavelength tenths and arbitrary small wire diameters, independent of the reduced kernel approximation and the printed source model used.

Exact EM field excited by a short horizontal wire antenna lying on a conducting soil

To date, only under restrictive assumptions can we derive closed-form expressions for the fields generated by an electrically small horizontal wire antenna situated on a planar conducting soil. Such assumptions limit the validity of the derived formulas to specified frequency ranges, or to the case of highly-conducting material media. The purpose of this work is to relax all the constraints underlying the derivation of the previously published solutions to this half-space problem, and develop an analytical technique that allows to reduce the integral representations for the field components generated by the dipole source to a well-known elementary contour integral, whose evaluation is straightforward. Numerical results are presented to show the advantages of the obtained explicit formulas, which are valid regardless of the operating frequency, over the previous solutions.

DNA detection with top–down fabricated silicon nanowire transistor arrays in linear operation regime

Silicon nanowire field‐effect transistors (SiNW‐FETs) are offering a label‐free sensing of DNA molecules based on the detection of the biomolecules’ charges. Typically, the charge accumulation at the solid–liquid interface is leading to a change in surface potential of the device. In other works, this effect is usually displayed as change in conductance of the nanowires. In this paper, we show that our topdown processed SiNW‐FET devices can be regarded as long‐channel, ion‐sensitive field‐effect transistor devices (ISFETs) and that their electronic characteristics can be fitted by an advanced MOSFET model taking narrow channel effects into account. In DNA experiments, changes in threshold voltage upon immobilization of capture DNA and hybridization with complementary target DNA were recorded as reported before. The signal amplitudes were scaling with different concentrations of electrolyte buffer as known from the commonly used Poisson–Boltzmann theory. In reports from other groups, the sensitivity of SiNW‐FETs was reported to be superior compared to ISFETs and scaling effects were observed with smaller wires having higher sensitivities. From our experiments, it seems that the immobilization of the DNA to the wire structure is leading to two effects: firstly, the threshold voltage is changing, leading to a shift in the transistors’ transfer characteristics similar to what was described for ISFET devices. In addition, upon DNA binding, a general increase in charge carrier density inside the nanowire is leading to an enhanced conductance. We assume that the latter effect is scaling with nanowire dimensions, while the surface effect is typically constant for all sensor structures.

Behaviour and Strength of Ferrocement Rectangular Beams in Shear- A Experimental Study

Ferrocement is another form of reinforced concrete in which the cement mortar is reinforced with closely spaced layers of continuous and relatively small diameter wire mesh. Early applications of Ferrocement have been to building of boats. Its application to terrestrial structures started much later. The experimental investigation includes casting and testing of 24 rectangular beams and 8 cubes. The specimens were divided into eight series; A to H according to the volume fraction of reinforcement, compressive strength of the mortar, and amount of reinforcement was varied in Series A to H by varying the number of layers of wire mesh. Specimens in these series were symmetrically reinforced with 4, 6, 8 and 10 layers of wire mesh, respectively, and were lumped together near each face with a clear cover of 5 mm. Series E and F were identical to Series D except for the compressive strength of the mortar. The remaining two Series G and H were also identical to Series D, but the amount of reinforcement near the compression face was different. While the specimens in Series H were provided with two layers of wire mesh, those in Series G contained no reinforcement near the compression face. The parameter investigated in each series was the shear-span-to -depth ratio a/h, which was achieved by varying the shear span to overall depth ratio from 1 to 2 at increments of 0.5 for the sake of simplicity since several reinforcement layers were involved.

Helical spring design optimization for endoscopic devices using a design-of-experiments approach

Event Abstract Back to Event Helical spring design optimization for endoscopic devices using a design-of-experiments approach Hamid Ebrahimi1, 2, Albert Yee1, 2, 3 and Cari Whyne1, 2, 3 1 Sunnybrook Research Institute, Holland Musculoskeletal Program, Canada 2 University of Toronto, Institute of Biomaterials and Biomedical Engineering, Canada 3 University of Toronto, Department of Surgery, Canada Introduction: Endoscopes are long thin tubular devices for non-invasive visualization of the interior of cavities, canals and vessels. They can be inserted through natural orifices or small surgical incisions. A typical endoscope outer diameter is 10mm and length can vary from 70 to 180mm[1]. While some rigid endoscopes are used, the flexibility of articulated endoscopes is important in many clinical applications. Articulated endoscopes are generally controlled by cables and levers which bend the distal extremity of the device to enable route selection or to change the field of view. Challenges of flexible endoscopes include reliable advancement and steerability of the device tip[2]. Reliable advancement can be addressed by utilization of relatively rigid helical springs within the device shaft. However, steerability requires that the tip must be flexible to accommodate different bend radii. The aim of this study is to understand the main effects (geometric and physical properties of the tip and their interactions) that impact the radius of curvature governing steerability in traditional endoscopes. Methods: Using the Abaqus Scripting Interface (ASI), a helical coil and cable assembly were modeled with the cable connected to the coil proximal circumference (Figure 1). The cable was placed inside the helical spring to represent a common endoscope design configuration. A two-level factorial design-of-experiments methodology was utilized to understand the main geometric and physical effects and their interactions on the attainable radius of curvature (outcome). The effects of five coil parameters were assessed: pitch, height, Young’s modulus (E), applied force, and wire width. Abaqus dynamic/explicit was utilized to analyse 32 models generated using ASI. The results were analyzed using a commercial design-of-experiments-specific statistical package (Design-Ease). Based on the Box-Cox plot, a Log transformation of the output response was used to stabilize the variance. A Sum-of-Squares chart with a 2% weighted contribution threshold was utilized to determine the model inclusion criteria. Analysis of variance (with a Bonferroni correction) was used to determine the significance of the model, effects, and interactions. Results: The model, four of the input parameters (height, E, force, and wire width) and two interactions (between pitch/wire width and pitch/height/E/wire width) were found to be statistically significant (P<0.0001). The largest contribution to the model was wire width (effect=1.39, 58.33% contribution). The force and pitch/wire width interaction each had a negative influence, reducing the radius of curvature (allowing for tighter bends), whereas the height, E, wire width and pitch/height/E/wire width interaction showed a positive influence. Pitch and all other interaction effects below the 2% contribution threshold were applied as model error. Using this model, geometric and physical properties can be optimized to meet specific endoscopic tip design criteria. A small pitch and wire width yield a radius of curvature optimal for acute bending radii, however, if due to design restrictions, a larger wire width is necessary, an increase in pitch may accommodate to yield a sufficiently small bending radius. Conclusion: A robust computational model was developed using a design-of-experiments approach that allows parametric optimization of endoscopic tip design parameters for radius of curvature minimization. Canadian Institutes of Health Research (CIHR)

A Simplified Low-${Q}$ Electrically Small Magnetic Dipole Antenna

An electrically small wire cage antenna is presented as an alternative to previously proposed spherical split-ring (SSR) antennas, which achieve ${Q}$ 's near the lower limit defined by Chu. This design is targeted to approach the same lower bound, but constructed in a manner more economical for production. The proposed dual-polarized wire cage structure is produced using a standard dielectric substrate which is patterned front and back with copper, using well-defined and reproducible etching procedures. The thin interdigitated structure is then placed over a ground plane using rigid conducting elements that help to suspend the dielectric substrate while completing the wire cage. A parameterized HFSS model was used to optimize performance. Measurements were made on fabricated prototypes that demonstrate performance consistent with simulated results, confirming that SSR antennas and their derivatives are capable of approaching Chu's limit on the radiation efficiency of electrically small antennas.

Sustaining the inter-wire arc in twin-wire indirect arc welding

A study of sustaining or igniting the arc between tips of two wires in twin-wire indirect arc welding (TWIAW) with AC is challenging. In comparison with conventional gas metal arc welding (GMAW) where one of the arc terminals is the base metal which is stationary and large, both arc terminals in TWIAW are wire tips which are small and subject to variations. The alternating of the polarity among the two wires in AC TWIAW further increases the challenge in sustaining the arc between the two wires. To meet the challenges, i.e., sustaining the arc between the small and varying wire tips despite the alternating polarity, the effects on the arc behaviors from different working parameters are observed, measured and analyzed in this study. The inter-wire distance which characterizes the instability of the inter-wire arc between the two wires in TWIAW is found to increase as the AC current frequency, the inter-wire angle and the wire diameter decrease as well as the amperage of the current increases. This definite tendency provides the foundation to control the inter-wire melting and droplet detachment/metal transfer to successfully sustain the inter-wire between the two small wires dynamically such that the AC TWIAW may operate as desired to deliver its desirable properties—low heat input and high deposition rate.

A new technique of closed intramedullary nailing in fractures of the proximal humerus with varus deformity

Introduction. Varus displacement is common in fractures of the proximal humerus. Development of new low invasive surgical modalities providing anatomy restoration and non-traumatic fracture fixation is actual. Purpose of the study was development of the low invasive technique of closed interlocking nailing providing reduction of the typical varus displacement in fractures and posttraumatic deformities of the proximal humerus. Material and methods. A new technique of correction of the proximal humerus in fractures and posttraumatic deformities was applied in 12 patients - 7 with two-part fractures and 5 with posttraumatic varus deformities. The surgical technique includes application of a small wire circular external frame. Its proximal part is secured to the humeral head to reduce varus displacement along with connection to the distal part of the frame, and the reached alignment is fixed by an intramedullary nail. Results. In all 12 cases we succeeded to reduce the varus deformity. At 1 year follow-up healing was reached in 11 patients, and in one patient exchange compression nailing was performed. Constant score in 1 year was 76±17 after fracture treament, and 70±16 in posttraumatic deformities, which corresponeded to good results. Conclusion. The presented technique allows to reach 40-50° angular correction without open approach and significant soft tissue damage. The obtained results confirm efficacy of the new technique and pertinence of its use in patients with fractures and posttraumatic deformities of this localization. The introduced technique of closed nailing appears to be a promising approach in reconstructive surgery of the proximal humerus.

Resection of a physeal bar with complete transverse osteotomy at the metaphysis and Ilizarov external fixation.

The traditional techniques involving an oblique tunnel or triangular wedge resection to approach a central or mixed-type physeal bar are hindered by poor visualisation of the bar. This may be overcome by a complete transverse osteotomy at the metaphysis near the growth plate or a direct vertical approach to the bar. Ilizarov external fixation using small wires allows firm fixation of the short physis-bearing fragment, and can also correct an associated angular deformity and permit limb lengthening. We accurately approached and successfully excised ten central- or mixed-type bars; six in the distal femur, two in the proximal tibia and two in the distal tibia, without damaging the uninvolved physis, and corrected the associated angular deformity and leg-length discrepancy. Callus formation was slightly delayed because of periosteal elevation and stretching during resection of the bar. The resultant resection of the bar was satisfactory in seven patients and fair in three as assessed using a by a modified Williamson-Staheli classification.

Infrared thermometers for small wires drawing

This work describes the design of two contactless thermometers based respectively on a total radiance and two-color pyrometry scheme, developed to measure the temperature of a small brass coated steel wire during wire drawing. In this critical condition, wire oscillation and relevant insertion errors do not allow using commercial contact or contactless sensors. Thus, ad hoc pyrometers optical layouts have been designed in order to minimize sensitivity to the wire oscillations and emissivity changes. Moreover, performances associated to different infrared detectors have been compared using as figure of merit the achieved measurement uncertainty simulating typical disturbances, i.e. the background temperature variation, the slope of the wire’s emissivity and the effect of the atmosphere transmittance. Finally, the uncertainty budgets were drawn, evidencing the limitations of the proposed methods and identifying the best configuration for both developed instruments.

Wetting of steel by Al 4043 alloys in cold metal transfer process

The sessile drop method was used for the study of the wetting of steel by Al 4043 alloys in cold metal transfer process. The moving of triple line was determined by the reaction at interface rather than the wettability of reaction product. The evaporation of Zn coating for galvanised steel induced instability of wetting for small wire feed speeds and reduced the heat input in the interface. Wire feed speed dependent interfacial structures were observed, which are due to the heat input dependent interfacial reactivity. The calculation of adsorption energy can be used for the explanation of interfacial structures and Zn rich zone in Al galvanised steel system.

Ultrafast Carrier Dynamics of a Photo-Excited Germanium Nanowire–Air Metamaterial

Ultrafast carrier dynamics in arrays of single crystal and relatively uniform-diameter Ge nanowires (NWs) are investigated by transient absorption measurements and effective medium simulations. We present the first quantitative analysis of a Ge NW–air metamaterial, translating the photon response of the assemblies to carrier dynamics. Three time regimes of the ultrafast recombination process are identified: Auger recombination dominant (0–5 ps), “fast” surface trapping and recombination dominant (5–20 ps), and a mix of “fast” recombination and “slow” surface trapping (20–200 ps). The rates of surface recombination and their dependences on pump fluence are determined, highlighting the different interactions of electrons and holes with Ge NW surface and interface states. Structural and excitation conditions can be engineered to extend the photogenerated electron and hole lifetimes. Small wire diameters and low pump powers enhance the electron lifetime because charging of defect states in the surface oxide l...

Novel Si Etching and Dielectric Liner Film Processing Technologies for Low-Cost TSV Packaging

In recent years, "2.5D silicon interposers" and "Full 3D stacked" technology for high-performance LSI circuits has attracted much attention since this technology can solve interconnection problems by using TSVs (Through Silicon Vias) to electrically connect stacked LSI circuits. 2.5D and 3D Si integration has great advantages over conventional 2D devices such as a high packaging density, small wire length, high-speed operation, low power consumption, and a high feasibility for parallel processing. Yet, the problem of cost-effective TSV production is still to be solved. In particular, the demand for a new plating bath technology to shorten the Cu plating time is pressing. In addition, TSV isolation liner materials will be necessary with lower cost for the production of future high-frequency devices. A new etch process has been developed for scallop-free and taper-shaped TSV fabrication [1]. By using a direct etch process instead of cycled etching, TSVs were obtained with smooth-sidewalls and tapered profiles. The absence of scallops has a positive effect on signal transmission speed. Also, the direct etch process allows for shorter TSV fill process times and thus provides lower cost of deposition processes like PE-CVD, PVD and Cu-ECP (electrochemical plating) [2,3]. A cost correlation of taper-shape etching and Cu-ECP (electro-chemical plating) will be included. For the TSV isolation, polyurea dielectric liners were successfully deposited using a vapor deposition polymerization technology (which is Ulvac’s FPF/PV large panel technology). This process allows for isolation liners in next-generation high-frequency devices and for the film formation into a TSV pattern. In summary, a novel low-cost TSV fabrication flow can be provided for 2.5 / 3D Si integration in high-frequency applications. The process flow yields scallop-free and taper TSVs, which can be filled effectively with electroplated copper and polyurea dielectric liners.

Failure Analysis of Crane Wire Rope

A failure analysis of a broken multi strand wire rope from an offshore platform crane was performed. The wire rope was operated for less than 5 years. The wire consists of seven strands, one central strand and six strands around it. The diameter of the small wires was about 0.78-0.94 mm and the larger wires was a round of 1.52 - 1.78 mm. The large size wires were found fractured by cyclic torsional stresses as characterized by the presence of fatigue cracking originating from the outer surface of the wire. Meanwhile the smaller wires were fractured in a ductile manner under excessive load after the larger wire broken out due to the fatigue mechanism.

Evolution of treatment mechanics and contemporary appliance design in orthodontics: A 40-year perspective.

Until the early 1970s, successful treatment with the Begg technique and the Tweed edgewise technique required tedious wire bending. The introduction of Andrews' straight wire appliance changed that, and it was one of the most significant contributions in the history of orthodontics. The straight wire appliance significantly reduced the amount of wire bending and also brought along other options in treatment mechanics. Retraction of the canines with elastic chains and ligature wires became more common. Sliding mechanics in place of closing loops became the method of space closure for a significant number of clinicians. Edgewise force levels were initially used to close spaces; however, it was soon observed that lighter forces were more effective with sliding mechanics. Along with these changes, it became apparent that compensation in the appliance was needed, depending on the type of malocclusion and particularly with varying extraction sequences. Various appliance designs were developed to accommodate changes in mechanics and force levels. These modifications improved tooth positions at the end of treatment as long as the brackets were properly placed. These major changes in appliances, force levels, and treatment mechanics can be traced back to the work of Dr Lawrence Andrews and the straight wire appliances.

Boiling Heat Transfer to Dilute Emulsions From a Vertical Heated Strip

Heat transfer measurements for nucleate pool boiling of a dilute emulsion on a short vertical surface are reported. The vertical surface is a thin steel ribbon of 1.35 mm height × 101 mm length. Direct current resistance heating produces boiling either on the surface or in the free convection boundary layer of dilute emulsions of pentane in water and FC-72 in water. Single phase and boiling heat transfer is measured for emulsions with a volume fraction of the dispersed component of 0.1% and 0.5% in a pool at approximately 25 °C. The dispersed component is created by a simple atomization process and no surfactants are employed to maintain the droplets of the dispersed phase in suspension. In free convection, the presence of the dispersed component somewhat impedes heat transfer, but when boiling commences enhancement of heat transfer is observed. Boiling is observed in the emulsions at lower surface temperatures than for water alone, and significantly more superheat is required to initiate boiling of the dispersed component than would be needed for a pool of the dispersed component alone. Consequently, a temperature over shoot is observed prior to initiation of boiling, and such an over shoot has been observed in several prior studies. Boiling heat fluxes are compared to recently published measurements of boiling in similar emulsions on a small diameter horizontal wire. Boiling generally occurs at a slightly higher degree of superheat of the dispersed component on the heated strip as compared to thin wires.

The influence of a small upstream wire on transition in a rotating cylinder wake

Recent experimental research on rotating cylinder wakes has found that a previously numerically predicted subharmonic instability mode, mode C, occurs for considerably lower rotation rates than predicted through stability analysis, yet other mode transitions occur closer to the predicted onset. One difference between the theoretical and experimental set-ups is the use of a small-diameter hydrogen bubble visualisation wire placed upstream of the rotating cylinder. The current paper tests the hypothesis that a wire, of only $1/100$th of the cylinder diameter, placed five diameters upstream of the cylinder, sufficiently perturbs the flow to substantially affect certain wake transitions, including the onset of mode C. This is achieved using stability analysis of a flow that includes the upstream wire. The results indeed show that the wire of a tiny diameter induces a non-negligible asymmetry in the flow, triggering the subharmonic mode at substantially lower rotation rates. Furthermore, at higher rotation rates, the onset of two other three-dimensional modes are delayed to higher Reynolds numbers. These results make the point that even seemingly minute perturbations caused by minimally intrusive methods may result in substantially altered experimental flow behaviour.

Modeling and Analysis of Crosstalk Induced Effects in Multiwalled Carbon Nanotube Bundle Interconnects: An ABCD Parameter-Based Approach

In this paper, the crosstalk effects in both small and large diameter multiwalled carbon nanotube bundle interconnects (MWCNTs) for the future nanoscale integrated circuits are studied with the help of ABCD parameter matrix approach for global levels of interconnects at 22- and 14-nm technology nodes. Here, isolated MWCNTs are modeled using an equivalent single conductor transmission line. The simulation results show that the results are at par with the result of SPICE model. It is observed that performance wise, the large diameter MWCNT bundles are better than both small diameter MWCNT bundles and copper wire for both repeated and unrepeated interconnects. The same trend is observed with the number of inserted repeaters. For repeated wires, the optimized placement of repeaters offsets the delay advantage numbers of MWCNT bundles over copper wire. Technology scaling adversely impacts the delay advantage numbers of small diameter MWCNT bundles. As far as the worst-case crosstalk noise peak voltage is concerned, the large diameter MWCNT bundles also outperform both small diameter MWCNT bundles and copper wire for longer interconnects. However, for shorter interconnects, copper wire and small diameter bundles outclass the large diameter bundles due to their relatively larger time constant. We have compared our crosstalk analysis results with the earlier work to justify the validity of our proposed model and observed that the results with our model are in well conformity with the existing work. It is seen that even the tall Cu vias are not going to significantly affect the performance of MWCNT bundle interconnects. Twice the minimum width global level interconnects are the optimal choice to achieve the maximum delay advantage using MWCNT bundle interconnects in comparison with Cu-based interconnects. Finally, our analysis shows that from the performance and signal integrity perspective, the large diameter MWCNT bundles are a suitable alternative to both small diameter MWCNT bundles and copper interconnects for future integrated circuit technology generations.

Surface superconductivity in thin cylindrical Bi nanowire.

The physical origin and the nature of superconductivity in nanostructured Bi remains puzzling. Here, we report transport measurements of individual cylindrical single-crystal Bi nanowires, 20 and 32 nm in diameter. In contrast to nonsuperconducting Bi nanoribbons with two flat surfaces, cylindrical Bi nanowires show superconductivity below 1.3 K. However, their superconducting critical magnetic fields decrease with their diameter, which is the opposite of the expected behavior for thin superconducting wires. Quasiperiodic oscillations of magnetoresistance were observed in perpendicular fields but were not seen in the parallel orientation. These results can be understood by a model of surface superconductivity with an enhanced surface-to-bulk volume in small diameter wires, where the superconductivity originates from the strained surface states of the nanowires due to the surface curvature-induced stress.