bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of SiH3 Diffusion in Determining the Surface Smoothness of Plasma-Deposited Amorphous Si Thin Films: An Atomic-Scale Analysis
Authors: Valipa Mayur S. , Bakos Tamas , Aydil Eray S. , Maroudas Dimitrios 
Published: June 2019

AbstractDevice-quality hydrogenated amorphous silicon (a-Si:H) thin films grown under conditions where the SiH3 radical is the dominant deposition precursor are remarkably smooth, as the SiH3 radical is very mobile and fills surface valleys during its diffusion on the a-Si:H surface. In this paper, we analyze atomic-scale mechanisms of SiH3 diffusion on a-Si:H surfaces based on molecular-dynamics simulations of SiH3 radical impingement on surfaces of a-Si:H films. The computed average activation barrier for radical diffusion on a-Si:H is 0.16 eV. This low barrier is due to the weak adsorption of the radical onto the a-Si:H surface and its migration predominantly through overcoordination defects; this is consistent with our density functional theory calculations on crystalline Si surfaces. The diffusing SiH3 radical incorporates preferentially into valleys on the a-Si:H surface when it transfers an H atom and forms a Si-Si backbond, even in the absence of dangling bonds.
Wiring and introduction of single silicon nanocrystals into multi-walled carbon nanotubes
Authors: Švrček Vladimir , Normand Francois Le , Ersen Ovidui , Pham-Huu Coung , Begin Dominique , Louis Benoit , Ledoux Marc-Jaques 
Published: June 2019

AbstractFor a long time the application of silicon technology for optoelectronics has been limited by the extremely poor generation of light by bulk silicon. However, the properties of Si were found to depend on its structure at a nanometric scale and bright photoluminescence from silicon nanocrystals (Si-nc) was discovered. In this work, the results obtained for the mechanical connecting of single Si-nc by two independent techniques are presented. First, the room temperature approach of connecting and introducing Si-nc embedded in colloidal suspensions by capillary forces within multi-walled carbon nanotubes (MWCNTs) and second, the direct growth of MWCNTs on single Si-nc coated with iron catalyst are described.
Correlation of In and Ex Situ Stress to Microstructures during Al-Induced Crystallization of PECVD Amorphous Silicon
Authors: Ray S. , Lian Y.G. , Sriram V. , Tucker D. J. , Pan G. Z. 
Published: June 2019

AbstractWe studied the correlation of in and ex situ stress to microstructures during Al-induced crystallization for structures of Al on top (AOT) and Al on bottom (AOB) of amorphous Si (a-Si) on 3000 Å SiO2 coated on Si wafers and found that a-Si deposited on PECVD SiO2 and Al increases the stress compressively, and Al deposited on PECVD SiO2 and on a-Si decreases the stress tensilely. In addition, the stress of AOB structures is in general less than that of AOT structures. Correlation of stress to microstructures indicated that the difference in microstructures between AOT and AOB results from the nature of the layer structures themselves. By using modified Stoney's equation, the lower stress of AOB structures than AOT could be explained with existence of oxide between a-Si and Al for both AOT and AOB structures.
Electronic Properties of Improved Amorphous Silicon-Germanium Alloys Deposited by a Low Temperature Hot Wire Chemical Vapor Deposition Process
Authors: Datta Shouvik , Cohen J. David , Xu Yueqin , Mahan A. H. 
Published: June 2019

AbstractWe report novel material properties of a series of a-Si,Ge:H alloys grown by hot-wire chemical vapor deposition under low filament temperature (˜1800°C) and low substrate temperature (˜200-300°C). These alloys exhibit significantly improved electronic properties including low defect densities and sharp band tails (Urbach energies ≤ 45meV even for Ge fractions as high as 47at.%). On the other hand, comparisons of the transient photocapacitance and transient photocurrent spectra do not indicate very efficient hole collection in these materials. We found two distinct regimes of light-induced degradation in the alloy sample with 29at.% Ge fraction, possibly corresponding to the light induced increase of Ge and Si dangling bonds, respectively.
Experimental Study of Silane Plasma Nanoparticle Formation in Amorphous Silicon Thin Films
Authors: Thompson S. , Perrey C. R. , Belich T. J. , Blackwell C. , Carter C. B. , Kakalios J. , Kortshagen U. 
Published: June 2019

AbstractRF glow discharge deposited hydrogenated amorphous silicon films containing silicon nanocrystalline inclusions (a/nc-Si:H) films are investigated as a function of a thermal gradient applied across the silane plasma during film growth. The a/nc-Si:H films are synthesized from hydrogen-diluted silane plasmas when a capacitively-coupled plasma enhanced chemical vapor deposition reactor is operated at high gas chamber pressures. Plasma diagnostics and transmission electron microscopy image analysis of films deposited with and without a thermal gradient suggest that nanoparticle formation occurs within the plasma, rather than resulting from solid-state nucleation at the growing film surface.
Hot-mesh Chemical Vapor Deposition for 3C-SiC Growth on Si and SiO2
Authors: Yasui Kanji , Eto Jyunpei , Narita Yuzuru , Takata Masasuke , Akahane Tadashi 
Published: June 2019

AbstractThe crystal growth of SiC films on (100) Si and thermally oxidized Si (SiO2/Si) substrates by hot-mesh chemical vapor deposition (HMCVD) using monomethylsilane as a source gas was investigated. A mesh structure of hot tungsten (W) wire was used as a catalyzer. At substrate temperatures above 750°C and at a mesh temperature of 1600°C, 3C-SiC crystal was epitaxially grown on (100) Si substrates. From the X-ray rocking curve spectra of the (311) peak, SiC was also epitaxially grown in the substrate plane. On the basis of the X-ray diffraction (XRD) measurements, on the other hand, the growth of (100)-oriented 3C-SiC films on SiO2/Si substrates was determined to be achieved at substrate temperatures of 750-800°C, while polycrystalline SiC films, at substrate temperatures above 850°C. From the dependence of growth rate on substrate temperature and W-mesh temperature, the growth mechanism of SiC crystal by HMCVD was discussed.
Study of the Oxidation of Polycrystalline SiGe: Formation of Ge Nanocrystals and their Related Luminescence
Authors: Prieto A. C. , Avella M. , Jiménez J. , Rodríguez A. , Sangrador J. , Rodríguez T. , Kling A. 
Published: June 2019

AbstractPolycrystalline SiGe layers have been oxidized in either dry or wet atmospheres. The evolution of the growing oxides and the SiGe layer during the oxidation processes have been characterized using Raman spectroscopy, X-ray diffraction, Rutherford backscattering and Fourier transform infrared spectroscopy. Formation of Ge nanocrystals has been observed for both oxidation atmospheres. Violet luminescence emission has been observed and its relation to the oxidation processes has been studied. The luminescence is unambiguously related to the presence of these Ge nanocrystals. Since it does not exhibit quantum confinement, it must be related to defects linked to the nanocrystals.
Fabrication of One-dimensional Silicon Nano-wires Based on Proximity Effects of Electron-beam Lithography
Authors: Hu S. F. , Sung C. L. 
Published: June 2019

AbstractOne-dimensional silicon nanowire structures have been successfully made by using the proximity and accumulation effects of electron-beam (e-beam) lithography. Wire structures are fabricated in a thin poly silicon layer on a silicon substrate with a 400 nm buried SiO2. Measurements of the current-voltage characteristics at various temperatures from 4 K up to 300 K show significant nonlinearities and single-electron effect behavior. The blockade size is significantly affected by thermal effects, oscillations of the blockade, and the conductivity dependence on the gate potential.
Advances in Amorphous Silicon Integrated Photonics Science and Technology
Authors: Halada G.P. , Chawda Samrat , Mawyin J. , Tonucci R.J. , Mahan A.H. , Fortmann C.M. 
Published: June 2019

AbstractOver the past few years we have been developing a scientific basis for amorphous silicon-based integrated photonics technology. Waveguides using hydrogen-implanted, optically-smooth, hot-wire-deposited films have been prepared and demonstrated, and structures were characterized by Raman spectroscopy of the implanted and the non-implanted regions of the waveguide samples. The analysis is consistent with greater disorder in the film structure induced through implantation. More recently, materials prepared by femtosecond laser ablation of silicon powder have been characterized by Raman spectroscopy indicating a structure having both amorphous and crystalline components. As amorphous silicon photonics continues to evolve, the patterning of materials of differing crystallinity may become an issue of interest.
Two-dimensional a-Si:H/a-SiC:H n-i-p sensor array with ITO/a-SiNx antireflection coating
Authors: Vygranenko Yu. , Chang J. H. , Nathan A. 
Published: June 2019

AbstractThis paper presents a two-dimensional a–Si:H/a-SiC:H n–i–p photodiode array with switching diode readout, developed specifically for fluorescence-based bio-assays. Both device structure and fabrication processing has enabled enhancement of the external quantum efficiency of the encapsulated device up to 80%, reduction of the photodiode leakage down to 10 pA/cm2 at -1V reverse bias, and increase of the rectification current ratio of the switching diodes up to 109. The critical fabrication issues associated with deposition of device-quality materials, tailoring of defects at the i–p interface, device patterning with dry etching, junction passivation, and contact formation will be discussed. Both sensing and switching diodes were characterized. While the observed dark current in the photodiodes at low reverse bias voltages is primarily due to carrier emission from deep states in the a–Si:H bulk, the leakage in the small switching diodes stems from peripheral defects along junction sidewalls. Optical losses in the photodiodes with ITO/a–SiNx:H antireflection coating were evaluated using numerical modeling, and the calculated transmission spectra correlated well with the spectral response characteristics. Measurements of the charge transfer time and output linearity demonstrated the efficiency of the single-switching diode readout configuration. The response of the array to optical excitation was also investigated. The observed long term retardation in the signal rise and decay at illumination levels less than 1010 photons/cm2-s can be associated with charge trapping in the undoped layer.
Amorphous Silicon Based p-i-i-n Structure for Color Sensor
Authors: Zhang S. , Raniero L. , Fortunato E. , Pereira L. , Águas H. , Ferreira I. , Martins R. 
Published: June 2019

AbstractThis work deals with the study of the role of the film thickness and composition on the color selectivity of the collecting spectrum of glass/ZnO:Ga/p-a-Si1-xCx:H/ a-Si1-xCx:H /a-Si:H/n-a-Si:H/Al photoelectronic detectors produced in a single chamber plasma enhanced chemical vapor deposition (PECVD) system. The cross contaminations were minimized by a rotate-cover substrate holder system. The devices can detect the blue illumination at small reverse bias and detect red illumination at large reverse bias. The role of the process parameters, especially the thickness of the p-type and intrinsic a-Si1-xCx:H, and the intrinsic a-Si:H layers on the device performances were studied in detail aiming to achieve a better detectivity.
Comparison of the Effect of Light Soaking in Porous Silicon and a-Si:H
Authors: Mandal N. P. , Agarwal S. C. 
Published: June 2019

AbstractIn undoped a-Si:H thin films, light soaking (LS) decreases dark current and photocurrent and increases the electron spin resonance signal monotonically with increasing exposure time, (Staebler-Wronski Effect, SWE). On the other hand, in porous silicon (PS) the light-soaking effect is non-monotonic. For short durations, LS increases dark current, photo current and photoluminescence and decreases the ESR signal. Long exposures of PS, however, have the opposite effect, which is similar to the SWE observed in a-Si:H. All metastabilities in PS as well as in a-Si:H can be removed by annealing, but not by exposure to infrared light. We find that the combined effect of NH3vapor exposure and LS on PS yields a final state that depends upon the order in which the two steps are performed. This is in contrast to the corresponding observation in a-Si:H. We could arrest the light-induced degradation of PS over long times by coating with a thin polystyrene, which resulted in constant PL and ESR intensities. However, in the case of a-Si:H the polymer coating decreases the SWE, but does not eliminate it. The results can be understood, if we were to propose that LS affects the surface in PS, but affects mainly the bulk in a-Si:H.
Solid state MAS NMR spectroscopic characterization of plasma damage and UV modification of low k dielectric films
Authors: Abell Thomas , Houthoofd Kristof , Iacopi Francesca , Grobet Piet , Maex Karen 
Published: June 2019

Abstract29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy was employed to characterize short-range atomic structure modifications to low k dielectric films that were subjected to post-deposition plasma exposure or UV curing. Comparison of spectra from single thick depositions of a CVD low k film (k∼3.0) with sequential thin depositions of the same film revealed ∼3% increase in Si-O crosslinking that was attributed to interfacial plasma damage. Comparison of a second CVD low k film (k∼3.0) before and after UV curing revealed ∼11% increase in Si-O crosslinking with commensurate losses of Si-OH and Si-CH3 groups. UV curing was believed to result in bulk modification. This crosslinking was found to increase the Young's modulus of the film from 11 to 16 GPa as measured on 700 nm films by nanoindentation. NMR analysis was found to provide significant information beyond that provided by FTIR but required special sample preparation and extensive data collection.
Flip Chip Reliability of GaAs on Si Thinfilm Substrates Using AuSn Solder Bumps
Authors: Oppermann Hermann , Hutter Matthias , Klein Matthias , Engelmann Gunter , Toepper Michael , Wolf Jürgen 
Published: June 2019

AbstractAu/Sn solder bumps are mainly used for flip chip assembly of compound semiconductors in optoelectronic and RF applications. They allow a fluxless assembly which is required to avoid contamination of optical interfaces and the metallurgy is well suited to the final gold metallization on GaAs or InP. Flip chip assembly experiments were carried out using two layer Au/Sn bumps as plated without prior bump reflow. An RF and reliability test vehicles comprise a GaAs chip which was flip chip soldered on a silicon substrate. Temperature cycling tests with and without underfiller were performed. The different failure modes for underfilled and nonunderfilled samples were discussed and compared. Additional reliability tests were performed with flip chip bonding by gold thermocompression for comparison. The test results and the failure modes are discussed in detail.
Interconnects for Elastically Stretchable and Deformable Electronic Surfaces
Authors: Jones Joyelle , Lacour S.P. , Wagner Sigurd 
Published: June 2019

AbstractDeformable, large-area electronic surfaces are desirable for many human-machine interfaces. The goal of our research is to fabricate elastically deformable electronics by integrating electronic devices and stretchable interconnects onto a flexible substrate. The focus of this paper is the fabrication and electrical performance of the stretchable interconnects. Au was deposited onto a silicone elastomer (PDMS) and patterned to achieve a resolution of 2 μm. Two patterning techniques are presented: patterning by shadow mask and patterning by photolithography. Photolithographic patterning on PDMS is not straightforward. First, we discuss the challenges in patterning and then the morphology of lines patterned by both techniques. The electrical resistance of the Au lines under tensile strain is presented. Interconnects patterned by shadow mask remain electrically conductive up to 100 % strain. Those patterned by photolithography maintain electrical conductivity when strained up to 60 %.
Double-layered Structure of Surface Modification of Low-k Dielectrics Induced by He Plasma
Authors: Yanai Ken-Ichi , Hasebe Tadayoshi , Sumiya Kouji , Oguni Seiki , Koga Kazuhiro 
Published: June 2019

AbstractSurface modification of a p-SiOC film induced by Helium (He) plasma was investigated using various measurements. Differential Fourier transform infrared absorption (FT-IR) spectra and the etch-depth measurements with the immersion in the mixed hydrofluoric acid (HF) indicate that the almost all of Si-CH3 bonds are broken in the modification layer, resulting in carbon-depletion, an SiO2-like composition. The x-ray photoelectron spectroscopy (XPS) measurements at different take-off angles reveal that the modified surface forms a double-layered structure, a thin carbon-rich top layer (about 1 nm thick) on a thick carbon-depletion layer (about 20 nm thick) with the irradiation of He plasma over 300 W. Atomic force microscopy (AFM) observations show that the modified surface is the smoothest in the case of the carbon-depletion surface.
Fracture Property Improvements of a Nanoporous Thin Film Via Post Deposition Bond Modifications
Authors: Jacques Jeannette M. , Tsui Ting Y. , McKerrow Andrew J. , Kraft Robert 
Published: June 2019

AbstractFor 90 nm node devices, the group of materials known as organosilicate glass (OSG) has emerged as the predominant choice for intermetal dielectrics. A potential failure mechanism for this class of low-k dielectric films during the manufacturing process is catastrophic fracture due to channel cracking. The use of an electron beam curing process is being investigated for improvement in the mechanical strength of these silicon-based materials. Within this work, the effects of curing dose (micro-C/cm2) upon the mechanical properties of OSG thin films were characterized. For a set process voltage and current, linear relationships exist between the dose and several mechanical film properties. Channel crack growth velocities were also measured for these cured materials. As the cure dose is increased, the crack growth rate decreases according to a power law relationship. The structural film changes induced by the electron beam cure process are addressed, focusing on their impact upon the mechanical strength of OSG thin films.
Structure Evolution in Plated Cu Films
Authors: Field D.P. , Park NJ , Besser PR , Sanchez JE 
Published: June 2019

AbstractStructure evolution in plated Cu films is a function of sublayer stacking, film thickness, plating chemistry, plating parameters, and temperature. The present work examines grain growth and texture evolution in annealed plated Cu on a 25 nm thick Ta sublayer for films of 480 and 750 nm in thickness. These results are compared against those obtained from damascene Cu lines fabricated from a similar process, using a series of line widths. The results show that the initial structures of the plated films are similar, with slightly weaker (111) texture, a higher fraction of twin boundaries, and larger grains in the thicker films. The microstructure of the Cu within the trench constraints is a strong function of line geometry with the propensity for twin boundary development controlling structural evolution.
Effect of Temperature on Incubation Time for Spontaneous Morphology Change in Electrodeposited Copper Metallization
Authors: Ahmed S. , Buckley D.N. , Nakahara S. , Kuo Y. 
Published: June 2019

AbstractA systematic investigation of the effect of annealing time and temperature on the incubation period for spontaneous morphology change (SMC) in electrodeposited copper metallization is reported. The incubation time is greatly reduced at higher temperatures. At each temperature, the remaining incubation time at room temperature was found to decrease approximately linearly with increasing annealing time. An Arhennius plot of the measured rates of decrease showed good linearity and yielded a value of 0.48 eV for the activation energy. This is consistent with a vacancy diffusion mechanism for the process occurring during the incubation period and supports our proposed mechanism for SMC.
Integration of ALD-TaN Liners on Nanoporous Dielectrics
Authors: Moon Bum Ki , Iijima Tadashi , Malhotra Sandra , Simon Andrew , Shaw Thomas , Ryan Todd , Labelle Cathy , Fuller Nick , Bolom Tibor , Dunn Derren , Flaitz Philip , Mehta Sanjay , Inoue Keishi , McGahay Vincent 
Published: June 2019

AbstractUltra-thin ALD-TaN/PVD-Ta liners have been developed to prevent Cu diffusion into porous interlayer dielectric (ILD) materials envisioned for future copper interconnections. The porous ultra-lowk(p-ULK) film is prepared using the spin-on method, and typical k-value and the average pore size of p-ULK used in this paper are 2.3 and 2-3 nm, respectively. Interaction and phenomena at the ILD/ALD-TaN interface have been investigated, and the electrical measurements of samples with a bi-layered ALD-TaN/PVD-Ta barrier were performed after completing the metallization and CMP process.A deep penetration of ALD-TaN was observed on the as-deposited p-ULK, which is due to the interconnected pore structures. However, the surface of the p-ULK is drastically changed after the etch process, where changes are attributed to plasma damage and re-deposition of etched species. Pores can therefore be sealed during the etch process. Furthermore, the plasma damage makes the sidewall more hydrophilic, which may promote the growth of ALD-TaN layer. Based on EELS and EDS profiles, there is no signature of TaN penetration into the etched p-ULK at M1 level with a sharp Ta peak, which indicates excellent stability of ultra-thin ALD-TaN liner.An oxidation test in air ambient and at elevated temperature confirmed the barrier properties of the stacked ALD-TaN/PVD-Ta layers. Any weak point in the barrier allows the Cu to oxidize and to make a color change under an optical microscope. However, all of our samples showed no color change, which implies that the barrier is very uniform and stable. Electrical properties measured at M1 showed excellent results. Our results demonstrate the ability to successfully integrate ALD-TaN barriers with a nanoporous ULK film.
Degradation of Fracture and Fatigue Properties of MEMS Structures Under Cyclic Loading
Authors: Kim Jong-Jin , Kwon Dongil 
Published: June 2019

AbstractThe fracture and fatigue properties of LIGA nickel MEMS structures were evaluated by microtensile and fatigue test methods. A microtensile/fatigue device was developed and specimens with feature size ten micrometers were used. The fatigue property was derived from displacement amplitude – the number of cycles to failure curve by applying a dynamic load with a piezoelectric actuator. The tensile/fracture properties after various cyclic loading were also measured. Both fatigue and tensile test results showed a cyclic softening phenomenon.