bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical Precursor Routes to Nanostructured Non-oxide Ceramics
Authors: Forsthoefel Kersten M. , Pender Mark J. , Sneddon Larry G. 
Published: June 2019

AbstractAn efficient route to boron carbide, boron nitride, and silicon carbide ceramic nanofibers and nanotubules has been developed which employs newly developed molecular and polymeric precursors in conjunction with porous alumina templating methods. Melt infiltration or vacuum filtration of solutions of 6,6 -(CH2)6-(B10H13)2 or polyhexenyldecaborane through alumina templates followed by pyrolysis and dissolution of the membranes in 48% HF yielded boron carbide nanofibers or nanotubules. Boron nitride nanotubules were generated in a similar fashion by employing polyborazylene as a precursor, while silicon carbide nanotubules were generated from the commercially available allylhydridopolycarbosilane (AHPCS) polymeric precursor. In all cases, SEM and TEM analyses showed aligned, monodispersed ensembles of nanofibers or nanotubules. Structural control of the end products can be achieved through changes in concentration of the precursor solution, the number of alumina membrane treatments, and/or pore size of the alumina template.
Quantum Size Effect Silicon Structures via Molecularly Self-Assembled Hybrid Templates
Authors: Guliants Elena A. , Carreon Moises A. , Abeysinghe Don C. , Ji Chunhai , Anderson Wayne A. , Guliants Vadim V. 
Published: June 2019

AbstractA novel approach for the synthesis of advanced functional inorganic materials with atomic-scale control over the size of periodic features on the sub-30 nm scale is presented. The key innovative aspect of this technique is the direct, bottom-up formation of a two-dimensional periodic array of spatially separated nanostructures in a self-organized thin-film porous template. This thin-film template is fabricated via biologically inspired hierarchical self-assembly of organic surfactant molecules in the presence of inorganic charged silicate species. The removal of organic molecules from such an organic/inorganic hybrid system creates a periodic array of pore channels of ∼3-30 nm diameter inside the thin-film silica template. This porous template is employed as a shadow mask to directly grow various functional nanostructures inside the confined environment of the periodic pore arrays. In the present study, silicon nanostructures were grown inside the templates by both chemical and physical (sputtering) vapor deposition. The quantum size effect was clearly pronounced in the room temperature photoluminescence spectra of the samples prepared by sputtering from a Si target, which makes the approach highly promising for the fabrication of nanoscale optoelectronic devices.
Comparison and Evolution of Copper CMP Consumable Technology
Authors: Evans David R. 
Published: June 2019

AbstractIntensive investigation of copper CMP over the past decade has revealed that consumable technology is of critical importance. There are several reasons for this, but all are ultimately due to the chemical and material properties of copper and associated barrier layers. Moreover, in comparison to conventional dielectric polishing, copper CMP (and, perhaps, metal CMP in general) is of a much more chemical nature. This is a consequence of the fact that metal removal generally requires an oxidation-reduction mechanism while, in contrast, dielectric removal typically requires only simple hydrolysis. As any chemist knows, oxidation-reduction reactions are often notoriously hard to control and easily upset by contaminants. Of course, contaminants can be intentionally added to the chemistry for beneficial purposes in which case they become known as “proprietary additives”.In addition, to the removal chemistry, abrasive and pad technology has also undergone considerable evolution. Indeed, free abrasive, fixed abrasive, and abrasiveless technologies have all been developed. In the case of fixed abrasive polishing, this has required modification of the pads as well, however conventional and abrasiveless polishing can be carried out with conventional polyurethane pads. This picture is further complicated by the various available hardware configurations and the use of multiplaten processes.
Silver Damascene Process with Cap Layer
Authors: Ota Masahiro , Tsujimura Manabu , Inoue Hiroaki , Ezawa Hirokazu , Miyata Masahiro 
Published: June 2019

AbstractDevelopment of semiconductors has proceeded according to broad frameworks such as the International Technology Roadmap for Semiconductors (ITRS). A key development in semiconductor technology involves the adoption of several new materials, such as Cu, low-k and high-k materials, and noble metals in capacitors, transistors, and/or interconnects. These developments will likely lead to wider application of the planarization process to new processes and new materials, and call for even stricter planarization performance requirements. One example involves planarizing Ag interconnects with an optimal cap layer configuration for reducing RC delays. The Cu interconnect process is currently used to reduce wire resistivity. One material that has been proposed as a successor to Cu is Ag. Many low-k materials have been developed with the goal of reducing dielectric constant (k). However, damascene design and matters such as cap layer configuration are also important considerations in reducing the effective dielectric constant (k eff). Our report herein begins by proposing Ni-B deposited by electroless plating as a candidate cap material, due to the following characteristics: (1) it offers good selectivity for Ag interconnects; (2) it provides good barrier effects through thermal processes; and (3) it provides good controllability of deposition rates. Next, we report that Ag damascene with Ni-B cap layer can be realized through electroplating and polishing of Ag interconnects. Although Ag polishing technologies are currently not fully developed, we suggest that they may nevertheless be successfully applied to polish Ag.
Mechanistic Understanding of Material Detachment During CMP Processing
Authors: Che Wei , Guo Yongjin , Bastawros Ashraf , Chandra Abhijit 
Published: June 2019

AbstractA combined experimental and numerical approach has been devised to understand the abrasion aspects of material removal mechanisms of ductile copper film on silicon wafers during Chemical mechanical planarization. The experimentally observed trends of the deformation patterns and the force profiles from micro and nano-single scratch experiments are used to guide numerical simulation using finite element simulation at the continuum scale and molecular dynamics simulation at the atomistic scale. Such integrated approach has provided several plausible mechanisms for material detachments through a combination of surface plowing and shearing under the abrasive particles. The gained insights can be integrated into mechanismbased models for the material removal rate in these processes as well as addressing possible defect formation.
Simulation of Nanoscale Polishing of Copper with Molecular Dynamics
Authors: Ye Y. , Biswas R. , Morris J. R. , Bastawros A. , Chandra A. 
Published: June 2019

AbstractWe investigate the fundamental atomistic processes in chemical mechanical polishing of copper, by simulating the nanoscale polishing of a copper surface by a single abrasive particle. The atomistic mechanisms of an individual surface-polishing event are simulated with molecular dynamics using the embedded atom method. The nature of material removal, chip formation, material defects and frictional forces were investigated as a function of the cutting speed, depth of cut, and abrasive geometry. Nanometric cutting comprises of two steps: material removal as the tool machines the top surface, followed by relaxation of the work material to a low defect configuration, after the tool or abrasive particle has passed over the machined region. Chemical etching processes during planarization considerably improve the quality of the planarized surface and reduce defects in the bulk.
Effect of CMP Pad Exposure to Aqueous Media on the Pad Properties. Part 1. Dynamic Mechanical and Modulated DSC Analysis
Authors: Tregub A. , Moinpour M. , Sorooshian J. 
Published: June 2019

AbstractSoaking of polyurethane-based CMP pad in oxide slurry, de-ionized water, and pH buffer solution, and its effect on thermal and mechanical properties of the pads was studied using Dynamic Mechanical Analysis and Modulated Differential Scanning Calorimetry. Pad softening due to soaking was established, and softening mechanisms are discussed. Diffusion of the aqueous medias to polyurethane pad was described using Fickian diffusion model.
Kinetics of Light-Induced Effects in Mixed-Phase Hydrogenated Silicon Solar Cells
Authors: Yuea Guozhen , Yan Baojie , Yang Jeffrey , Lord Kenneth , Guha Subhendu 
Published: June 2019

AbstractWe have observed a significant light-induced increase in the open-circuit voltage (Voc) of mixed-phase hydrogenated silicon solar cells. In this study, we investigate the kinetics of the light-induced effects. The results show that the cells with different initial Voc have different kinetic behavior. For the cells with a low initial Voc (less than 0.8 V), the increase in Voc is slow and does not saturate for light-soaking time of up to 16 hours. For the cells with medium initial Voc (0.8 ∼ 0.95 V), the Voc increases rapidly and then saturates. Cells with high initial Voc (0.95 ∼ 0.98 V) show an initial increase in Voc, followed bya Voc decrease. All light-soaked cells exhibit a degradation in fill factor. The temperature dependence of the kinetics shows that light soaking at high temperatures causes Voc increase to saturate faster than at low temperatures. The observed results can be explained by our recently proposed two-diode equivalent-circuit model for mixed-phase solar cells.
Hydrogenated Amorphous Silicon Thin Films with Nanocrystalline Silicon Inclusions
Authors: Belich T. J. , Thompson S. , Perrey C.R. , Kortshagen U. , Carter C.B. , Kakalios J. 
Published: June 2019

AbstractThin films of hydrogenated amorphous silicon containing nanocrystalline silicon inclusions (a/nc-Si:H) have been synthesized in an RF capacitively coupled PECVD system using a mixture of hydrogen diluted silane and helium, under deposition conditions at the edge of powder formation within the plasma. High resolution TEM confirms the presence of nanocrystallites as small as 2 nm in these films. Measurements of the optical absorption spectrum using CPM and PDS indicates a broadening of the Urbach slope in the a/nc-Si:H, compared to a-Si:H films, but no appreciable increase in midgap absorption. Despite the deposition conditions for the a/nc-Si:H being very different from those associated with producing optimal quality a-Si:H, the dark conductivity and photoconductivity values, and the sensitivity to light-induced defect creation in the a/nc-Si:H films are comparable to those in a-Si:H.
Metal Containing Link Formed in Amorphous Silicon Metal-To-Metal Antifuse
Authors: Hawley Frank , Issaq Farid , Ranaweera Jeewika , Lambertson Roy 
Published: June 2019

AbstractA Metal-to-Metal (M2M) antifuse is formed using hydrogenated amorphous silicon as a dielectric material between two refractory metal electrodes. The M2M antifuse is used as a programmable device in an FPGA, where it is placed between two interconnect metal layers of a Logic CMOS process. The M2M device may then be programmed to interconnect logic circuits. The resulting programmed link is an alloy of amorphous silicon and barrier metal that forms a low resistance path between the logic circuits.
Lifetime Measurements of Stain Etched and Passivated Porous Silicon
Authors: Guerrero-Lemus Ricardo , Ben-Hander Fathi A. , Ballif Cristoffer , Kenanoglu Ali , Borchert Dietmar , Hernández-Rodríguez Cecilio , Rodríguez Tomás , Martínez-Duart José M. 
Published: June 2019

AbstractIn this work we present the first experimental study of photocarrier lifetimes in p-type and n-type Si substrates in which stain etched porous silicon (PS) has been formed on the surface. The lifetime values have been obtained before and after the surface passivation of the samples. The surface pasivation has been produced by two different techniques: (i) hydrogen passivation by immersion of the samples in a HF solution; and (ii) deposition of SiNx in a plasma enhanced chemical vapour deposition system. The results show a degradation of the photocarrier lifetime when the porous layers are not adequately passivated. This lifetime degradation is mainly associated to a large concentration of rapid recombination centres located at the Si/PS interface. We have also detected a weak influence of the PS outermost dangling bonds to the photocarrier lifetimes.
Effect of SiO2 Capping Layer on a Laser Crystallization of a-Si Thin Film
Authors: Kang Myung-Koo , Kim Hyun Jae , Kang Sook Young , Lee Su-Kyung , Kim Chi-Woo , Chung Kyuha 
Published: June 2019

AbstractEffect of SiO2 capping layer(C/L) on recrystallization of amorphous Si (a-Si) film was investigated. When a thick C/L over 500 Å was deposited on an a-Si film before crystallization, fine p-Si grains less than 100nm were obtained at full range of energy density window. However, when a thin C/L below 200 Å was used, Si-melt spouted out through C/L at over critical energy density. When Si-melt started spouting, abrupt change of grain size also occurred. These large grains could be explained by a non-uniformity of heat flow caused by Si-melt spouting. With this polycrystalline Si (p-Si) material having appreciable grain size protected by C/L, fabrication of low-cost Low Temperature Poly Si (LTPS) without additional cleaning of p-Si surface could be successfully developed.
Observation and Annealing of Incomplete Recrystallized Junction Defects due to the Excimer Laser Beam Diffraction at the Gate Edge in Poly-Si TFT
Authors: Nam Woo-Jin , Park Kee-Chan , Jung Sang-Hoon , Park Soo-Jeong , Han Min-Koo 
Published: June 2019

AbstractIncomplete recrystallized junction defects of self-aligned, excimer laser annealed polycrystalline silicon (poly-Si) thin film transistor (TFT) was investigated by high-resolution transmission electron microscopy (HR-TEM). TEM observation and simulation result verify that the laser irradiation intensity decreased remarkably at the junction due to diffraction of laser beam at gate electrode edge. We proposed oblique-incidence excimer laser annealing method and successfully eliminated the residual junction defects.
2-Dimensional Controlled Large Lateral Grain Growth on the Floating Amorphous Silicon Film by Excimer Laser Recrystallization
Authors: Song In-Hyuk , Kang Su-Hyuk , Nam Woo-Jin , Han Min-Koo 
Published: June 2019

AbstractWe have successfully obtained large lateral grains with well-controlled grain boundary. The proposed excimer laser annealing (ELA) method produces 2-dimensionally controlled grain growth because the temperature gradient is induced in two directions. Along the channel direction, the floating active structure produces large thermal gradient due to very low thermal conductivity of the air-gap. Along the perpendicular direction to the channel, the surface tension effect also produces thermal gradient. The proposed ELA method can control the grain boundary perpendicular and parallel to current path with only one laser irradiation.
Mechanical Stress and Process Integration of Direct X-ray Detector and TFT in a-Si:H Technology
Authors: Lee Czang-Ho , Chan Isaac , Nathan Arokia 
Published: June 2019

AbstractThis paper presents an alternate strategy to reduce the mechanical stress issues pertinent to the process integration of molybdenum/hydrogenated amorphous silicon (Mo/a-Si:H) Schottky diodes and thin film transistors (TFTs), used as X-ray sensor pixels for medical imaging. The previous approach was to minimize the intrinsic stress in the Mo layer through appropriate process conditions and film thickness, but over narrow process latitude and with a compromise in X-ray sensitivity. Alternatively, the mechanical stress in Mo can be reduced by reducing and/or avoiding the extrinsic stress exerted on Mo by the underlying films through a different masking sequence in the fabrication. This modified process allows for a more flexible design of the Mo layer for enhanced X-ray sensitivity, while maintaining the mechanical integrity of the various layers. Also, the performance of the Schottky diode is improved, in terms of its forward current. The pixel shows good linearity in the X-ray response over the range of 40 ∼ 100 kVp.
Origin of the Low-Energy Photoluminescence in Microcrystalline Silicon Films
Authors: Lee Joon-Yong , Park Dong-Hyun , Yoon Jong-Hwan 
Published: June 2019

AbstractIn this work we have investigated the low-energy photoluminescence (PL) band with a peak between 0.8 eV and 1.0 eV for microcrystalline silicon films (μc-Si:H) grown under various growth conditions. At least four subbands are observed, the peaks of which are located near 0.80 eV, 0.87 eV, 0.92 eV, and 0.97 eV, respectively. It is suggested that the low-energy PL band basically arises from a superposition of these subbands, whose intensities strongly depend on deposition conditions, and thus its peak is determined by the sum of these subband intensities. From the results, it is suggested that the subband centered at 0.92 eV originates from defect-related radiative recombination in the amorphous phase rather than radiative band tail-to-tail transitions in the grain boundaries.
Fabrication of Novel TFT LCD Panels with High Aperture Ratio Using a-SiCO:H Films as a Passivation Layer
Authors: Hong W.S. , Jung K.W. , Hwang B.K. , Cerny G. , Yang S.H. , Choi J.H. , Chung K. 
Published: June 2019

AbstractFabrication of a novel TFT-LCD panel, using amorphous silicon oxycarbide (a-SiCO:H) films as a passivation layer, was successfully demonstrated for the first time. The a-SiCO:H low-k films were deposited using a standard PECVD (plasma-enhanced chemical vapor deposition) reactor from a gas mixture of trimethylsilane[Si(CH3)3H] and N2O. The resulting films have a dielectric constant between 2.7 and 3.5 and high optical transmittance in the range of visible lightThe transfer characteristics of the TFT's having a-SiCO:H as a passivation layer were comparable with that of a conventional TFT with a PECVD-grown SiNx passivation layer. Stability of the resulting TFT was performed under prolonged bias conditions, and the source-drain current was fairly constant over the test period. The LCD panel with the a-SiCO:H passivation layer showed 30% higher brightness than that of the standard panel.
Carrier Transport and Recombination In A-SI:H P-I-N Solar Cells in Dark and Under Illumination
Authors: Deng J. , Pearce J.M. , Vlahos V. , Koval R.J. , Collins R.W. , Wronski C.R. 
Published: June 2019

AbstractA study has been carried out on the forward bias dark current and the short circuit current -open circuit voltage characteristics of a-Si:H p-i-n solar cells over wide range of illumination intensities. Results are presented with superposition of these characteristics over extended current voltage regimes. This and the observed separation between these characteristics are consistent with the arguments presented based on first principle arguments. The conclusions drawn about the role of photo-generated carrier lifetimes, the densities of defects and the potential barriers in the i-layers adjacent to the n and p contacts are confirmed by numerical simulations. The key role of these potential barriers to the split in the characteristics offer new insight into both why the lack of superposition has been observed and the erroneous conclusions drawn about carrier transport for a-Si:H solar cells in the dark and under illumination.
Polymorphous Silicon Films Produced in Large Area Reactors by PECVD at 27.12 MHz and 13.56 MHz
Authors: Águas H. , Raniero L. , Pereira L. , Fortunato E. , Cabarrocas P. Roca i , Martins R. 
Published: June 2019

AbstractThis work refers to a study performed on polymorphous silicon (pm-Si:H) at excitation frequencies of 13.56 and 27.12 MHz in a large area PECVD reactor. The plasma was characterised by impedance probe measurements, aiming to identify the plasma conditions that lead to produce pm-Si:H films. The films produced were characterised by spectroscopic ellipsometry, infrared and Raman spectroscopy and hydrogen exodiffusion experiments, which are techniques that permit the structural characterisation of the pm-Si films and to study the possible differences between the films deposited at 13.56 and 27.12 MHz. Conductivity measurements were also performed to determine the transport properties of the films produced. The set of data obtained show that the 27.12 MHz pm-Si:H can be grown at higher rates with less hydrogen dilution and power density, being the resulting films denser, chemically more stable and with improved performances than the pm-Si:H films grown at 13.56 MHz.
Structural Characterization of Microcrystalline Silicon Solar Cells Fabricated by Conventional RF-PECVD
Authors: Li Liwei , Li Yuan-Min , Selvan J. A. Anna , Delahoy Alan E. , Levy Roland A. 
Published: June 2019

Absttact:Direct structural characterization of single junction p-i-n type μc-Si:H solar cells prepared in a single chamber, batch process type RF-PECVD system has been carried out using Raman scattering, XRD, and AFM. The overall degree of microcrystallinity of μc-Si:H i-layers is presented in terms of the ratio of peak intensities (Ic/Ia) of Raman shift at around 520 cm-1 and 480 cm-1, respectively. Strong correlations among device performance, i-layer structural properties, and uniformity have been established using information provided by such direct characterization. Our data support the notion that stable, high quality μc-Si i-layers are grown near the ‘edge’ of microcrystalline-to-amorphous phase transition. Solar cells made from such optimal areas exhibit moderate microcrystallinity (moderate Ic/Ia values). Preferential orientation corresponding to Si (220) planes was observed on those optimal solar cells, which also exhibit less-regular surface morphologies and lower surface roughness compared to that observed on solar cells with mixed-phase or highly crystalline Si:H i-layers.
Hollow Electrode Enhanced RF Glow Plasma Generation and its Application to the Fast Deposition of Microcrystalline Silicon Films
Authors: Tabuchi Toshihiro , Takashiri Masayuki , Toyoshima Yasumasa , Mizukami Hiroyuki 
Published: June 2019

AbstractA hollow electrode enhanced RF glow plasma excitation technique has been newly developed. In this technique, the reactor is divided into a capacitively-coupled RF glow discharge space and a processing space by the counter electrode, which includes a hollow structure and is placed between a RF electrode and the substrate. After introducing hydrogen gas into the chamber and applying RF power to the electrode, high intensity plasma emission is observed near and inside the hollow structure attached to the counter electrode. By using hollow RF electrode excitation in addition to the hollow counter electrode technique, it is found that plasma emission is further enhanced. The application of these discharge types for semiconductor processing is studied in the case of plasma enhanced chemical vapor deposition (PECVD) of hydrogenated microcrystalline silicon thin films. High crystallinity, photo-sensitivity and a maximum deposition rate of 4.9nm/s can all be achieved at a plasma excitation frequency of 13.56MHz and a temperature of 300°C. Properties of these plasmas are investigated by observing the plasma emission pattern and optical emission spectrum analysis. It is found that, using additional hollow RF electrode discharge, faster processing of device grade hydrogenated microcrystalline silicon thin films can be achieved under lower RF power compared to hollow counter electrode technique alone.