bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thin Film Transistors Made of Polysilicon Crystallized at 950°C on Steel Substrate
Authors: Wu Ming , Wagner Sigurd 
Published: April 2011

ABSTRACTWe fabricated top-gate polycrystalline silicon thin film transistors on steel foil substrates with two processes: (1) Directly deposited n+ source/drain layers. (2) Ion-implanted n+ source/drains. The steel substrates enable reducing the crystallization time of amorphous silicon to polysilicon from 4 hours at 600°C to 20 seconds at 900°C. Thin film transistors were made from polysilicon channel material crystallized at 950°C for either 20 seconds or 20 minutes. The steel foil substrates were passivated with SiO2. The best thin film transistors to date have mobilities of above 30cm2/Vs in both the linear and saturated regions.
Thin Film Transistors with Electron Mobility of 40 cm2V−1s−1 Made from Directly Deposited Intrinsic Microcrystalline Silicon
Authors: Cheng I-Chun , Wagner Sigurd , Mulato Marcelo 
Published: April 2011

ABSTRACTWe report top-gate n channel μc-Si:H TFTs with saturated electron mobilities up to 40 cm2V−1s−1 and ON/OFF ratios up to ~106. The μc-Si:H was grown from silane, dichlorosilane, and hydrogen. The glow discharge was excited at a frequency of 80 MHz to raise the growth rate to ∼1Å/sec, which is above that achievable with 13.56 MHz. Deposition temperatures were 230°C for the i-layer and 280°C (the highest temperature in the process) for the n+ source and drain layers. The TFTs were fabricated from 340-nm thick μc-Si:H films, and with a 300-nm thick gate insulator of plasma deposited SiO2.
Deposition of Heterogeneous Silicon Thin Films-Structure and Electric States-
Authors: Shimizu Isamu 
Published: April 2011

ABSTRACTHeterogeneous silicon thin films exhibited various microstructures were prepared by plasma enhanced(PE)-CVD from gaseous mixture of SiF4+H2 (SiH4) on glass substrate. Efficient parameters for controlling the microstructures were reviewed together with the way to grow crystalline seeds on glass by repeating the deposition and etching. Two step growth where polycrystalline silicon thin films were epitaxially grown on the seeds made on glass was proposed to accelerated the growth rate. The relationship between the microstructure and the carrier-transport properties are addressed, as well.
In-Situ Mass Spectroscopy of ECR Silane Plasmas for Amorphous and Microcrystalline Silicon Growth
Authors: Song Young J. , Guliants Elena , Lee Hak-Gyu , Anderson Wayne A. 
Published: April 2011

ABSTRACTECR silane plasmas for the deposition of a-Si:H and μc-Si films were investigated by in-situ mass spectroscopy (MS) using a quadrupole residual gas analyzer. The results showed that the intensities of ionic and neutral species (H, H2, He, Ar, Si and SiHx) in the 2 % SiH4/He plasma are strongly dependent on the deposition conditions such as chamber pressure, input power and hydrogen dilution. In all cases, the prevalence of Si ions was observed over SiH, SiH2 and SiH3 ions, suggesting a high decomposition rate of the silane in the plasma. In particular, the population of atomic hydrogen in the plasma seems to play a key role in the properties of both a-Si:H and μc-Si films. For example, the increased intensity of atomic hydrogen, compared to that of molecular hydrogen, resulted in the better quality a-Si:H film, showing a higher photo and dark conductivity ratio of ~105. The intensity of the hydrogen species was especially sensitive to the chamber pressure. The correlation between MS spectra and film properties is presented.
N-Type Silicon Films Produced by Hot Wire Technique
Authors: Ferreira Isabel M. M. , Cabrita Ana M. F. , Fortunato Elvira M. C. , Martins Rodrigo F. P. 
Published: April 2011

ABSTRACTThe role of the deposition pressure (p) and the type of filaments (tungsten, W or tantalum, Ta) used to produce large area (10cm×10cm) n-type Si:H films by hot wire chemical vapour (HW-CVD) deposition technique was investigated. The data show that the electro-optical properties of the films produced are dependent on the gas pressure used. In the pressure range of 1×10-3 Torr to 1.0 Torr, the room dark conductivity (σd) varies from 1×10-8 to 2 S/cm for films produced at the same hydrogen dilution and filament temperature (Tfil.). On the other hand, the hydrogen concentration (CH) decreases from 10% to 2%, while the growth rate (R) shows an exponential increase, from 1 to 9 Å/s. The SIMS analysis, within the detection limits, does not reveal the existence of any significant W or Ta contamination in the films produced.
The Influence of W Filament Alloying on the Electronic Properties of Hwcvd Deposited a-Si:H Films
Authors: Mahan A. H. , Mason A. , Nelson B. P. , Gallagher A. C. 
Published: April 2011

ABSTRACTIn depositing a-Si:H by HWCVD using W filaments, one issue common to this technique is that of filament lifetime. When using undiluted silane as the source gas, a buildup of silicon at the colder ends of the filament is routinely observed (thickening), and it is here that filament breakage usually occurs. Less well understood is the effect of filament alloy formation on a-Si:H electronic properties. In this work we combine ambipolar diffusion length (SSPG) measurements on consecutively deposited a-Si:H films with SEM surface topography and sputter (SP) Auger depth profiling of the filament Si/(W+Si) composition to track film electronic properties as a function of the Si buildup on short filaments entirely exposed to the growing film surface. We find that with increasing exposure time of the filament to silane, appreciable Si exists everywhere along the filament length, even in the non-thickened central regions. We discuss the effect of this alloying on the film deposition rate and electronic properties, and suggest that the nature of the filament surface must be carefully considered when optimizing a- Si:H film electronic properties. Finally, we discuss possible ways to minimize this alloying by post deposition treatments, which include different filament ‘run’ temperatures.
Thin Single Crystal Silicon on Oxide by Lateral Solid Phase Epitaxy of Amorphous Silicon and Silicon Germanium
Authors: Greene Brian J. , Valentino Joseph , Hoyt Judy L. , Gibbons James F. 
Published: April 2011

ABSTRACTThe fabrication of 250 Å thick, undoped, single crystal silicon on insulator by lateral solid phase epitaxial growth from amorphous silicon on oxide patterned (001) silicon substrates is reported. Amorphous silicon was grown by low pressure chemical vapor deposition at 525°C using disilane. Annealing at temperatures between 540 and 570°C is used to accomplish the lateral epitaxial growth. The process makes use of a Si/Si1-xGex/Si stacked structure and selective etching. The thin Si1-xGex etch stop layer (x=0.2) is deposited in the amorphous phase and crystallized simultaneously with the Si layers. The lateral growth distance of the epitaxial region was 2.5 μm from the substrate seed window. This represents a final lateral to vertical aspect ratio of 100:1 for the single crystal silicon over oxide regions after selective etching of the top sacrificial Si layer. The effects of Ge incorporation on the lateral epitaxial growth process are also discussed. The lateral epitaxial growth rate of 20% Ge alloys is enhanced by roughly a factor of three compared to the rate of Si films at an anneal temperature of 555°C. Increased random nucleation rates associated with Ge alloy films are shown to be an important consideration when employing Si1-xGex to enhance lateral growth or as an etch stop layer.
Via Electromigration Lifetime Improvement of Aluminum Dual-Damascene Interconnects by Using Soft Low-k Organic SOG Interlayer Dielectrics
Authors: Kaneko Hisashi , Usui Takamasa , Ito Sachiyo , Hasunuma Masahiko 
Published: April 2011

AbstractThe via electromigration(EM) reliability of aluminum(Al) dual-damascene interconnects by using Niobium(Nb) new reflow liner is described. It has been found that the via EM lifetime was improved by introducing low-k organic spin on glass(SOG)-passivated structure than the conventional TEOS-SiO2/SiN-passivated structure. Higher EM activation energy of 1.08 eV was obtained for the SOG-passivated structure than the conventional TEOS-passivated structure of 0.9 eV, even though no significant Al micro-crystal structure difference was found for both structures. It has been turned out that the low-k SOG material has the 1/7 Young's modulus (8 GPa) of TEOS-SiO2 (57 GPa) or thermal SiO2(70 GPa). The small Young's modulus means that SOG is more elastically deformable and/or softer than TEOS or thermal SiO2. This elastic deformation of the low-k SOG could retard the tensile stress evolution due to the Al atom migration near the cathode via, and elongated the time until the Al interconnect tensile stress exceeds the critical stress value for void nucleation. It has been concluded that the small-RC and reliable multi-level Al interconnect can be realized by the Nb-liner reflow-sputtered process with soft and low-k SOG dielectric materials.
Synthetic Control and Properties of Processible Poly(Methylsilsesquioxane)S
Authors: Lee Jin-Kyu , Char Kookheon , Kim Hie-Joon , Rhee Hee-Woo , Ro Hyun-Wook , Yoo Dae Young , Yoon Do Y. 
Published: April 2011

AbstractProcessible poly(methylsilsesquioxane)s (PMSSQs) were prepared in THF solution under nitrogen atmosphere in the presence of HCl catalyst. It was found that various reaction parameters such as concentration, temperature, reaction time, the amount of water, and the amount of acid catalyst could affect the molecular weight and the amount of functional end groups of PMSSQ samples. Thin films prepared from our PMSSQ samples by spin-coating followed by curing to 420°C exhibited a much better crack resistance than those presented in the literature, while the dielectric constant remained practically the same, i.e., ca. 2.7.
Characterisation of Low-K Dielectric Films by Ellipsometric Porosimetry
Authors: Baklanov M.R. , Mogilnikov K.P. 
Published: April 2011

AbstractEllipsometric porosimetry (EP) is a simple and effective method for the characterization of the porosity (volume of both open and close pores), average pore size, specific surface area and pore size distribution (PSD) in thin porous films deposited on top of any smooth solid substrat e. Because a laser probe is used, small surface area can be analyzed. Therefore, EP can be used on patterned wafers and it is compatible with microelectronic technology. This method is a new version of adsorption (BET) porosimetry. In situ ellipsometry is used to determine the amount of adsorptive which adsorbed/condensed in the film. Change in refractive index is used to calculate of the quantity of adsorptive present in the film. EP also allows the study of thermal stability, adsorption and swelling properties of low-K dielectric films. Room temperature EP based on the adsorption of vapor of some suitable organic solvents and method of calculation of porosity and PSD is discussed. Examination of the validity of Gurvitsch rule for various organic adsorptives (toluene, heptane, carbon tetrachloride and isopropyl alcohol) has been carried out to assess the reliability of measurements of pore size distribution by the ellipsometric porosimetry.
Structural Analyses of Fluorine-Doped Silicon Dioxide Dielectric Thin Films by Micro-Raman Spectroscopy
Authors: Coffer Jeffery L. , Zerda T. Waldek , Taylor Kelly J. , Martin Scott 
Published: April 2011

AbstractFluorine-doped silicon dioxide, a dielectric material compatible with copper integration, has received considerable attention for applications requiring a k value in the 3.5 to 4.0 range. Given the influence of structure on desired properties, convenient experimental structural probes of this type of material are of widespread interest. This work focuses on Raman spectroscopic analyses of ring defects in fluorine-doped silicon dioxide films prepared by plasma enhanced chemical vapor deposition (PECVD) as well as high density plasma methods (HDP). These measurements are complemented by ab initio computational simulations of the ring defects in these films and the impact of nearby fluorine on their stability. The impact of aging on these structures and correlations of observed trends with experimental techniques such as X-ray fluorescence are also described.
Seed-layer Deposition for Sub 0.25 µm Cu Metallization Using a Line Cusp Magnetron Plasma Source
Authors: Wickramanayaka Sunil , Nagahama Hanako , Watanabe Eisaku , Hayashi Toshihiko , Sato Makoto , Nakagawa Yukito , Hasegawa Shinya , Mizuno Shigeru , Numasawa Yoichiro 
Published: April 2011

AbstractA magnetically enhanced capacitively coupled plasma source was developed for sputter deposition of Cu seed layers on sub 0.25µm via or contact holes. The plasma source is of planer parallel plate configuration where the Cu target plate is one of the electrodes. For the generation of plasma, 60 MHz rf power is selected in order to increase the plasma density. Additionally, a line cusp magnetic field is used to further increase the plasma density. The film deposition rate and uniformity obtained with this plasma source is∼200 nm/min and ∼±5%, respectively. The Cu film resistivity lies around 2 µωcm. This sputtering system yields good film coverage on bottom and sidewalls of via holes with an aspect ratio > 5; therefore, a perfect Cu filling could be realized by electroplating process.
Organic Solution Deposition of Copper Seed Layers onto Barrier Metals
Authors: Gu H. , Fang R. , O'Keefe T. J. , O'Keefe M. J. , Shih W.-S. , Snook J. A. M. , Leedy K. D. , Cortez R. 
Published: April 2011

AbstractSpontaneous deposition of copper seed layers from metal bearing organic based solutions onto sputter deposited titanium, titanium nitride, and tantalum diffusion barrier thin films has been demonstrated. Based on electrochemically driven cementation exchange reactions, the process was used to produce adherent, selectively deposited copper metal particulate films on blanket and patterned barrier metal thin films on silicon substrates. The organic solution deposited copper films were capable of acting as seed layers for subsequent electrolytic and electroless copper deposition processes using standard plating baths. Electroless and electrolytic copper films from 0.1µm to 1.0µm thick were produced on a variety of samples on which the organic solution copper acted as the initial catalytic seed layer. The feasibility of using organic solution deposited palladium as a seed layer followed by electroless copper deposition has also been demonstrated. In addition, experiments conducted on patterned barrier metal samples with exposed areas of dielectric such as polyimide indicated that no organic solution copper or palladium deposition occurred on the insulating materials.
Structural Characterization Of Laser Lift-Off GaN
Authors: Stach Eric A. , Kelsch M. , Wong W.S. , Nelson E.C. , Sands T. , Cheung N.W. 
Published: April 2011

AbstractLaser lift-off and bonding has been demonstrated as a viable route for the integration of III-nitride opto-electronics with mainstream device technology. A critical remaining question is the structural and chemical quality of the layers following lift-off. In this paper, we present detailed structural and chemical characterization of both the epitaxial layer and the substrate using standard transmission electron microscopy techniques. Conventional diffraction contrast and high resolution electron microscopy indicate that the structural alteration of the material is limited to approximately the first 50 nm. Energy dispersive electron spectroscopy line profiles show that intermixing is also confined to similar thicknesses. These results indicate that laser lift-off of even thin layers is likely to result in materials suitable for device integration. Additionally, because the damage to the sapphire substrate is minimal, it should be possible to polish and re-use these substrates for subsequent heteroepitaxial growths, resulting in significant economic benefits.
Magnetic Field Generation at Early-Stage KrF Excimer Laser Ablation Of Solid Substrates
Authors: Hong M. H. , Lu Y. F. , Foong A. , Chong T.C. 
Published: April 2011

AbstractMagnetic field generation at early-stage of KrF excimer laser ablation of solid substrates (for delay time less than 200 ns) is investigated. Based on classical electrodynamics, fast and dynamic emission of electrons and positive ions at the beginning of laser ablation induces an electromagnetic field nearby. A tiny iron probe wrapped with 50-turn coil is applied to detect this dynamic magnetic field. It is found that signal waveform is closely related to probe distance from the laser spot. For probe distance less than a threshold, the signal has a double-peak profile with a negative peak appearing first and peak durations in tens of nanoseconds. As probe distance increases, the amplitude of positive peak reduces much faster than the negative one. It disappears for probe distance up to the threshold and signal waveform becomes a negative peak with a wider duration. Mechanism on magnetic field generation at early-stage of laser ablation is analyzed to obtain more information on charged particle dynamics. Dependence of the magnetic signal on laser fluence, substrate bias and pulse number is also studied during laser ablation of solid substrates and removal of metallic oxide layer on the surface.
Optimization of The Processing Parameters for Pulsed Laser Deposition of Nickel Silicide Ohmic Contacts On SiC
Authors: Richardson C. J. K. , Wisnioski M. H. , Spicer J. B. , Demaree J. D. , Cole M. W. , Hubbard C. W. , Joshi P. C. , Hirvonen J. K. , Kim H. , Pique A. , Chrisey D. B. 
Published: April 2011

AbstractThis research investigates the potential of pulsed laser deposition to create reliable high current ohmic contacts of Ni2Si on single crystal 4H-SiC. Since this stoichiometry is the stable interphase in the nickel-silicon carbide diffusion couple, direct deposition eliminates the detrimental excess carbon normally formed by direct sintering Ni on SiC, the surface roughening that results from this sintering as well as the need for post-deposition high-temperature (900°C) anneals that are required in complex multi-component contacts. This study examines the processing parameters that must be used during deposition to obtain the desired microstructural characteristics for the contact. Pulsed laser deposition of nickel silicide produces smooth films with an amorphous or nanocrystalline structure interspersed with macroparticles. Macroparticle formation on the resulting films appear in the form of solidified droplets of the eutectic composition nickel silicide (3:1) that form during the long term target processing. The dependence of the number and size distributions of these droplets on laser fluence sample temperature is examined.
Atomistic Simulations of the (1014) Surface of Carbonate Minerals
Authors: Wright Kate , Cygan Randall T. , Slater Ben 
Published: April 2011

ABSTRACTAtomistic simulation methods have been used to model the structure of the (1014) surfaces of calcite, dolomite, and magnesite under dry and wet conditions. The potential parameters for the carbonate and water species contain shell terms to model the polarizability of the oxygen atoms. These static calculations show that the surfaces undergo relaxation leading to the rotation and distortion of the carbonate groups with associated movement of cations. The dry surface energies are 0.322, 0.247, and 0.256 Jm−2 for calcite, dolomite, and magnesite respectively. The influence of water on the surface structure and energies has been investigated for monolayer coverage. When fully hydrated with a monolayer of water, the surface energy for calcite is reduced indicating a stabilization of the surface with hydration. The extent of carbonate group distortion is greater for the dry surfaces compared to the hydrated surfaces, and for the dry calcite relative to that for dry magnesite.
Organic Light-Emitting Diodes Using Triphenylamine Based Hole Transporting Materials
Authors: Fujikawa Hisayoshi , Ishii Masahiko , Tokito Shizuo , Taga Yasunori 
Published: April 2011

ABSTRACTThe durability of the tris(8-quinolinolato) aluminum based light-emitting diode (LED) is related to the thermal stability of the hole transport layer. Several linear linkage triphenylamine oligomers were used for the hole transport layer. The thermal stability was clearly seen to depend on a glass transition temperature (Tg) of the hole transporting material, and a linear relationship between the Tg and the thermal stability was found. A lowering of “turn-on voltage” for light emission and an increase of luminous efficiency with increasing temperature was also observed. Excellent durability of the organic LED with a tetramer of triphenylamine was achieved at a high temperature of 120°C. Our results indicate that the linear linkage of triphenylamine leads to a high Tg and high device performance at high temperatures.
Simulation of the Influence of Interface Charge on Electron Emission
Authors: Jensen Kevin L. , Shaw Jonathan L. 
Published: April 2011

ABSTRACTSeveral materials are promising candidates for electron sources. For diamond, a tunneling interface at the back contact limits injecting charge into the conduction band, but a purely geometric model of internal field emission is inadequate to explain experimental data. The presence of a defect, modeled by a coulomb charge, within the tunneling barrier region significantly enhances transmission and, in concert with a geometrical model, may better account for observed current levels. Charge has been suggested to play a similar role in the SiO2 covering on a single tip silicon field emitter to explain experimental data. The tunneling theory in both cases is similar. In the present work, a general method for estimating electron transport and energy distributions through potential profiles, which describe both semiconductor interfaces and field emission potential barriers when a charged particle modifies the tunneling barrier, is developed. While the model is intended for treating a metal-semiconductor interface, it is cast here in terms of in a thin SiO2 coating over a silicon field emitter tip to enable qualitative comparisons with experimental data. Tunneling probabilities are found by numerically solving Schrödinger's Equation for a piece-wise linear potential using an Airy Function approach. A qualitative comparison to experimental energy distribution findings is possible by utilizing an analytical model of the field emitter tip from which current-voltage relations may be found.
Observation of Hot Electron Field Emission
Authors: Shaw Jonathan 
Published: April 2011

ABSTRACTWe report energy distributions of silicon Field Emitter Arrays coated with 50A of ZnO. The distributions reflect changes in the ZnO conductivity induced by annealing in vacuum, temperature, and annealing in hydrogen. An additional coating of titanium performed in-situ produced large additional changes. Emission from the ZnO at energies near the Fermi level increased with gate voltage only after hydrogen annealing, when hot, and after Ti coating. In those same cases the emission distribution contained a tail at energies above EF. The highenergy emission tail is due to a many-body or Auger process whereby holes injected below EF create hot electrons. Although emission from ZnO occurred at energies up to 8eV below EF, no high-energy tail was observed in the normal case. Thus emission appears to occur from isolated electrons in ZnO gap states in cases where the distribution lacks a high-energy tail. Conversely, emission above EF suggests that emission occurred from a metallic state such as an accumulated conduction band.