Center for High-Rate Nanomanufacturing Publications Copyright (c) 2013 Northeastern University All rights reserved. http://iris.lib.neu.edu/chn_pubs Recent documents in Center for High-Rate Nanomanufacturing Publications en-us Tue, 21 May 2013 16:15:39 PDT 3600 Resonance damping in ferromagnets and ferroelectrics http://iris.lib.neu.edu/chn_pubs/22 http://iris.lib.neu.edu/chn_pubs/22 Wed, 29 Jun 2011 09:38:52 PDT The phenomenological equations of motion for the relaxation of ordered phases of magnetized and polarized crystal phases can be developed in close analogy with one another. For the case of magnetized systems, the driving magnetic field intensity toward relaxation was developed by Gilbert. For the case of polarized systems, the driving electric field intensity toward relaxation was developed by Khalatnikov. The transport times for relaxation into thermal equilibrium can be attributed to viscous sound wave damping via magnetostriction for the magnetic case and electrostriction for the polarization case.

... ]]> Allan Widom Ferroelectricity Ferromagnetism Resonance Effect of different deposition mediums on the adhesion and removal of particles http://iris.lib.neu.edu/chn_pubs/21 http://iris.lib.neu.edu/chn_pubs/21 Wed, 29 Jun 2011 09:29:53 PDT The purpose of this study is to investigate the effect of the different deposition mediums on the adhesion and removal of particles. Polystyrene latex (PSL) particles (50 µm) are deposited on thermal oxide and silicon nitride coated silicon wafers using different suspension mediums: air, isopropyl alcohol (IPA), and deionized water and then removed in a dry environment. The results show that PSL particles deposited on oxide are easier to remove than those on nitride due to a higher van der Waals force in all deposition mediums. In addition, dry particles deposited in air are much easier to remove than those... ]]> S. Hu Integrated circuits - Wafer-scale integration Nanoparticles Analysis of scratches formed on oxide surface during chemical mechanical planarization http://iris.lib.neu.edu/chn_pubs/20 http://iris.lib.neu.edu/chn_pubs/20 Wed, 29 Jun 2011 09:03:16 PDT Scratch formation on patterned oxide wafers during the chemical mechanical planarization process was investigated. Silica and ceria slurries were used for polishing the experiments to observe the effect of abrasives on the scratch formation. Interlevel dielectric patterned wafers were used to study the scratch dimensions, and shallow trench isolation patterned wafers were used to study the effect of polishing parameters, such as pressure and rotational speed (head/platen). Similar shapes of scratches (chatter type) were observed with both types of slurries. The length of the scratch formed might be related to the period of contact between the wafer and the pad.... ]]> Jae-Gon Choi Integrated circuits - Wafer-scale integration Chemical mechanical planarization Direct measurement of graphene adhesion on silicon surface by intercalation of nanoparticles http://iris.lib.neu.edu/chn_pubs/19 http://iris.lib.neu.edu/chn_pubs/19 Wed, 29 Jun 2011 08:54:03 PDT We report a technique to characterize adhesion of monolayered/multilayered graphene sheets on silicon wafer. Nanoparticles trapped at graphene-silicon interface act as point wedges to support axisymmetric blisters. Local adhesion strength is found by measuring the particle height and blister radius using a scanning electron microscope. Adhesion energy of the typical graphene-silicon interface is measured to be 151±28 mJ/m2. The proposed method and our measurements provide insights in fabrication and reliability of microelectromechanical/nanoelectromechanical systems.

... ]]> Zong Zong Integrated circuits - Wafer-scale integration Graphene Nanoparticles Parylene-C passivated carbon nanotube flexible transistors http://iris.lib.neu.edu/chn_pubs/18 http://iris.lib.neu.edu/chn_pubs/18 Wed, 29 Jun 2011 08:11:40 PDT Carbon nanotubes are extremely sensitive to the molecular species in the environment and hence require a proper passivation technique to isolate them against environmental variations for the realization of reliable nanoelectronic devices. In this paper, we demonstrate a parylene-C passivation approach for CNT thin film transistors fabricated on a flexible substrate. The CNT transistors are encapsulated with 1 and 3 μm thick parylene-C coatings, and the transistor characteristics are investigated before and after passivation. Our findings indicate that thin parylene-C films can be utilized as passivation layers for CNT transistors and this versatile technique can be readily applied for the... ]]> Selvapraba Selvarasah Nanotubes Nanoelectronics Thin film transistors Metamaterials on parylene thin film substrates: design, fabrication, and characterization at terahertz frequency http://iris.lib.neu.edu/chn_pubs/17 http://iris.lib.neu.edu/chn_pubs/17 Wed, 29 Jun 2011 08:00:12 PDT We design, fabricate, and characterize terahertz (THz) resonant metamaterials on parylene free-standing thin film substrates. Several different metamaterials are investigated and our results show strong electromagnetic responses at THz frequencies ranging from 500 GHz to 2.5 THz. The complex frequency dependent dielectric properties of parylene are determined from inversion of reflection and transmission data, thus indicating that parylene is an ideal low loss substrate or coating material. The biostable and biocompatible properties of parylene coupled with the multifunctional exotic properties of metamaterials indicate great potential for medical purposes such as THz imaging for skin cancer detection.

... ]]> Xianliang Liu Metamaterials Thin films Low-voltage and short-channel pentacene field-effect transistors with top-contact geometry using parylene-C shadow masks http://iris.lib.neu.edu/chn_pubs/16 http://iris.lib.neu.edu/chn_pubs/16 Wed, 29 Jun 2011 07:36:04 PDT We have fabricated high-performance top-contact pentacene field-effect transistors using a nanometer-scale gate dielectric and parylene-C shadow masks. The high-capacitance gate dielectric, deposited by atomic layer deposition of aluminum oxide, resulted in a low operating voltage of 2.5 V. The flexible and conformal parylene-C shadow masks allowed fabrication of transistors with channel lengths of L = 5, 10, and 20 μm. The field-effect mobility of the transistors was μ = 1.14 (±0.08) cm²/V s on average, and the IMAX/IMIN ratio was greater than 10⁶.

... ]]> Yoonyoung Chung Field-effect transistors Organic electronics Nanostructured materials Interfacial and electrokinetic characterization of IPA solutions related to semiconductor wafer drying and cleaning http://iris.lib.neu.edu/chn_pubs/15 http://iris.lib.neu.edu/chn_pubs/15 Mon, 23 May 2011 10:33:38 PDT In this study, the interfacial and electrokinetic phenomena of mixtures of isopropyl alcohol (IPA) and deionized (DI) water in relation to semiconductor wafer drying is investigated. The dielectric constant of an IPA solution linearly decreased from 78 to 18 with the addition of IPA to DI water. The viscosity of IPA solutions increased as the volume percentage of IPA in DI water increased. The zeta potentials of silica particles and silicon wafers were also measured in IPA solutions. The zeta potential approached neutral values as the volume ratio of IPA in DI water increased. A surface tension decrease from 72... ]]> Jin-Goo Park Semiconductor wafers Experimental and analytical study of submicrometer particle removal from deep trenches http://iris.lib.neu.edu/chn_pubs/14 http://iris.lib.neu.edu/chn_pubs/14 Mon, 23 May 2011 10:21:22 PDT Particle removal from patterned wafers and trenches presents a tremendous challenge in semiconductor manufacturing. In this paper, the removal of 0.3 and 0.8 µm polystyrene latex (PSL) particles from high-aspect-ratio 500 µm deep trenches is investigated. An experimental, analytical, and computational study of the removal of submicrometer particles at different depths inside the trench is presented. Red fluorescent polystyrene latex (PSL) particles were used to verify particle removal. The particles are counted using scanning fluorescent microscopy. A single-wafer megasonic tank is used for the particle removal. The results show that once a particle is removed from the walls or the... ]]> Kaveh Bakhtari Semiconductors Particles Experimental and numerical investigation of nanoparticle removal using acoustic streaming and the effect of time http://iris.lib.neu.edu/chn_pubs/13 http://iris.lib.neu.edu/chn_pubs/13 Mon, 23 May 2011 10:13:41 PDT Theremoval of nanoparticles is becoming increasingly challenging as the minimumlinewidth continues to decrease in semiconductor manufacturing. In this paper,the removal of nanoparticles from flat substrates using acoustic streamingis investigated. Bare silicon wafers and masks with a 4 nmsilicon cap layer are cleaned. The silicon-cap films are usedin extreme ultraviolet masks to protect Mo–Si reflective multilayers. Theremoval of 63 nm polystyrene latex (PSL) particles from these substratesis conducted using single-wafer megasonic cleaning. The results show higherthan 99% removal of PSL nanoparticles. The results also showthat dilute SC1 provides faster removal of particles, which isalso verified by the analytical analysis. Particle removal... ]]> Kaveh Bakhtari Nanoparticles Acoustic streaming Semiconductors Parallel arrays of individually addressable single-walled carbon nanotube field-effect transistors http://iris.lib.neu.edu/chn_pubs/12 http://iris.lib.neu.edu/chn_pubs/12 Mon, 23 May 2011 09:17:17 PDT High-throughput field-effect transistors (FETs) containing over 300 disentangled, high-purity chemical-vapor-deposition-grown single-walled carbon nanotube (SWNT) channels have been fabricated in a three-step process that creates more than 160 individually addressable devices on a single silicon chip. This scheme gives a 96% device yield with output currents averaging 5.4 mA and reaching up to 17 mA at a 300 mV bias. Entirely semiconducting FETs are easily realized by a high current selective destruction of metallic tubes. The excellent dispersity and nearly-defect-free quality of the SWNT channels make these devices also useful for nanoscale chemical and biological sensor applications.

... ]]> Sarah Lastella Field-effect transistors Nanotubes Microelectromechanical systems Three dimensional controlled assembly of gold nanoparticles using a micromachined platform http://iris.lib.neu.edu/chn_pubs/11 http://iris.lib.neu.edu/chn_pubs/11 Mon, 23 May 2011 08:23:36 PDT By using optical lithographic procedures, the authors present a micromachined platform for large scale three dimensional (3D) assembly of gold nanoparticles with diameters of ∼ 50 nm. The gold nanoparticles are formed into 3D low resistance bridges (two terminal resistance of ∼ 40 Ω) interconnecting the two microelectrodes using ac dielectrophoresis. The thickness of the parylene interlevel dielectric can be adjusted to vary the height of the 3D platform for meeting different application requirements. This research represents a step towards realizing high density, three dimensional structures and devices for applications such as nanosensors, vertical integration of nanosystems, and characterization of... ]]> Nishant Khanduja Nanoparticles Microelectromechanical systems Scalable nanotemplate assisted directed assembly of single walled carbon nanotubes for nanoscale devices http://iris.lib.neu.edu/chn_pubs/10 http://iris.lib.neu.edu/chn_pubs/10 Mon, 23 May 2011 08:16:08 PDT The authors demonstrate precise alignment and controlled assembly of single wall nanotube (SWNT) bundles at a fast rate over large areas by combining electrophoresis and dip coating processes. SWNTs in solution are assembled on prepatterned features that are 80 nm wide and separated by 200 nm. The results show that the direction of substrate withdrawal significantly affects the orientation and alignment of the assembled SWNT bundles. I-V characterization is carried out to demonstrate electrical continuity of these assembled SWNT bundles.

... ]]> Prashanth Makaram Nanotubes Microelectromechanical systems High-throughput assembly of nanoelements in nanoporous alumina templates http://iris.lib.neu.edu/chn_pubs/9 http://iris.lib.neu.edu/chn_pubs/9 Mon, 23 May 2011 08:07:49 PDT The authors demonstrate a nanofabrication method utilizing nanoporous alumina templates which involves directed three dimensional assembly of nanoparticles inside the pores by means of an electrophoretic technique. In their demonstration, they have assembled polystyrene nanobeads with diameter of 50 nm inside nanopore arrays of height of 250 nm and diameter of 80 nm. Such a technique is particularly useful for large-scale, rapid assembly of nanoelements for potential device applications.

... ]]> Evin Gultepe Nanostructured materials Microelectromechanical systems Directed assembly of gold nanoparticle nanowires and networks for nanodevices http://iris.lib.neu.edu/chn_pubs/8 http://iris.lib.neu.edu/chn_pubs/8 Mon, 23 May 2011 07:48:12 PDT Alternating electric field is used to assemble gold nanoparticle nanowires from liquid suspensions. The effects of electrode geometry and the dielectrophoresis force on the chaining and branching of nanowire formation are investigated. The nanowire assembly processes are modeled using finite element calculations, and the particle trajectories under the combined influence of dielectrophoresis force and viscous drag are simulated. Nanoparticle nanowires with 10 nm resolution are fabricated. The wires can be further oriented along an externally introduced flow. This work provides an approach towards rapid assembly and organization of ultrasmall nanoparticle networks.

... ]]> Xugang Xiong Nanowires Nanoelectronics Electric circuits - Alternating current Contact resistance study of noble metals and alloy films using a scanning probe microscope test station http://iris.lib.neu.edu/chn_pubs/7 http://iris.lib.neu.edu/chn_pubs/7 Mon, 23 May 2011 07:33:56 PDT The proper selection of electrical contact materials is one of the critical steps in designing a metal contact microelectromechanical system (MEMS) switch. Ideally, the contact should have both very low contact resistance and high wear resistance. Unfortunately this combination cannot be easily achieved with the contact materials currently used in macroswitches because the available contact force in microswitches is generally insufficient (less than 1 mN) to break through nonconductive surface layers. As a step in the materials selection process, three noble metals, platinum (Pt), rhodium (Rh), ruthenium (Ru), and their alloys with gold (Au) were deposited as thin films on... ]]> Lei Chen Microelectromechanical systems Electric switchgear The effect of frictional and adhesion forces attributed to slurry particles on the surface quality of polished copper http://iris.lib.neu.edu/chn_pubs/6 http://iris.lib.neu.edu/chn_pubs/6 Tue, 17 May 2011 11:56:19 PDT The effect of frictional and adhesion forces attributed to slurry particles on the quality of copper surfaces was experimentally investigated during copper chemical mechanical planarization process. The highest frictional force of 9 Kgf and adhesion force of 5.83 nN were observed in a deionized water-based alumina slurry. On the other hand, the smallest frictional force of 4 Kgf and adhesion force of 0.38 nN were measured in an alumina slurry containing citric acid. However, frictional (6 Kgf) and adhesion (1 nN) forces of silica particles in the slurry were not significantly changed regardless of the addition of citric acid. These... ]]> Yi-Koan Hong Copper - Surfaces Slurry Toxicity of CdSe nanoparticles in Caco-2 cell cultures http://iris.lib.neu.edu/chn_pubs/5 http://iris.lib.neu.edu/chn_pubs/5 Tue, 17 May 2011 07:06:56 PDT Background
Potential routes of nanomaterial exposure include inhalation, dermal contact, and ingestion. Toxicology of inhalation of ultra-fine particles has been extensively studied; however, risks of nanomaterial exposure via ingestion are currently almost unknown. Using enterocyte-like Caco-2 cells as a small intestine epithelial model, the possible toxicity of CdSe quantum dot (QD) exposure via ingestion was investigated. Effect of simulated gastric fluid treatment on CdSe QD cytotoxicity was also studied.


Results
Commercially available CdSe QDs, which have a ZnS shell and poly-ethylene glycol (PEG) coating, and in-house prepared surfactant coated CdSe QDs were dosed to Caco-2 cells. Cell viability and attachment were studied... ]]> Lin Wang Nanostructured materials - Toxicology A parameter study of separation modes of adhering microcontacts http://iris.lib.neu.edu/chn_pubs/4 http://iris.lib.neu.edu/chn_pubs/4 Mon, 16 May 2011 13:56:19 PDT A finite element model was developed to study adhesion of elastic-plastic microcontacts in a previous investigation. An interesting result was the identification of two distinct separation modes, i.e. brittle and ductile separation. In the current study, that model is used to conduct a series of simulations to determine the influence of four nondimensional parameters (including the maximum load parameter) on the contact and on the separation modes. The results show that the parameter S (the ratio of the theoretical stress to the hardness) and δƒ/δc (representing the loading level) are the most important. Smaller S can only lead to brittle... ]]> Yan Du Contact mechanics Electric switchgear Microelectronics Nanoengineering of a negative-index binary-staircase lens for the optics regime http://iris.lib.neu.edu/chn_pubs/3 http://iris.lib.neu.edu/chn_pubs/3 Mon, 16 May 2011 13:29:56 PDT We show that a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction, thereby expanding the range of optical properties theoretically available for future optoelectronic devices. The mechanism for achieving a negative-index lens is based on exploiting the periodicity of the surface corrugation. By designing and nanofabricating a planoconcave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 μm that such negative-index concave lenses can focus plane waves. The beam propagation in the lens was studied experimentally and was in excellent agreement with the three-dimensional finite-difference time-domain numerical simulations.

... ]]> Bernard Didier F. Casse Nanophotonics Lenses