bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulsed Laser Deposition of Laterally Graded X-Ray Optical Multilayers on Substrates of Technical Relevance
Authors: Dietsch R. , Holz TH. , Krawietz R. , Mai H. , SchÖneich B. , Scholz R. , VÖllmar S. , Wehner B. 
Published: April 2011

ABSTRACTPulsed Laser Deposition (PLD) is used for the preparation of Ni/C, W/C, and Mo/Si multilayers having X-ray optical quality. For the synthesis of layer stacks involving a uniform or a graded thickness distribution across 4"-wafers the conventional thin film deposition equipment of PLD has been modified. This modification provides a precise spatial control of the plasma plume orientation in the deposition chamber. With this arrangement the emission characteristic of the plasma source can be computer controlled and the desired coating profile can be tailored across an extended substrate via a stepper-motor-driven target manipulator.Thus film thickness uniformity (δts < 2%) is obtained on substrates up to 4" diameter even for smaller target-substrate distances. For laterally graded Ni and C individual layers linear thickness gradients of dts/dx = 3.2 × 10−8 were confirmed over the total substrate length by spectroscopic ellipsometry. The parameters deduced from single layer deposition were applied for the synthesis of laterally graded Ni/C multilayers. A mean value of the gradient of the stack period thickness dt/dx = 6.2 × 10−8 confirmed by X-ray reflectometry (nominal value: dt0 /dx = 6.4×10−8 ) characterizes precision and reproducibility of the coating process.
Capacitance Humidity Sensor
Authors: Ralston Andrew R.K. , Thoma Paul E. , Klein Carl F. , Denton Denice D. 
Published: April 2011

ABSTRACTA capacitance relative humidity (RH) sensor is described that has a design, construction, and material composition that result in an inexpensive and robust sensor. This sensor has a multilayer, free-standing film construction. It consists of a humidity sensitive polyimide (PI) dielectric core and conductive layers consisting of carbon filled polysulfone on each side of the polyirnide film to form a capacitor. The polyimide used is a BPDA-ODA type, and replaces a PMDA-ODA type polyimide used in a previous version of this sensor. The BPDA-ODA sensor has a nominal capacitance of 200 pF and a nominal sensitivity of 13% at 100% RH. The characteristics of this humidity sensor are discussed and compared to the characteristics of the PMDA-ODA type sensor. Characteristics considered include the PI film moisture uptake and water vapor transmission, and the sensors' sensitivity to relative humidity, frequency response, and aging at 85°C/85% RH. The dual-state sorption model and free volume calculations are used to demonstrate that observed differences in the film are due to differences in chemical composition between the films.
Multilayer Precursor Synthesis of New Copper-Tungsten Selenides
Authors: Fister Loreli , Hornbostel Marc D. , Johnson David C. 
Published: April 2011

ABSTRACTWe have made new ternary compounds in the copper tungsten selenium system using multilayer thin films as reactants. The compounds appear to be unstable above temperatures near 1000ºC with respect to binary compounds, which helps to explain the difficulty in making these compounds by conventional methods.
High Quality NiFe/Ag Superlattices Made by Pulsed Laser Deposition (PLD)
Authors: Treece Randolph E. , Dorsey Paul , Horwitz James S. , Qadri Syed , Chrisey Douglas B. 
Published: April 2011

ABSTRACTHigh-quality thin-film superlattices of permalloy (NiFe) and silver (Ag) have been grown by pulsed laser deposition (PLD) for the first time. The alternating metallic layers weregrown from individual NiFe and Ag targets utilizing an automated multi-target holder coupled to a conventional PLD system. The targets were ablated at a base pressure of 4×10−7 Torr and the material deposited on room-temperature (100) silicon and on fused silica substrates. The films were characterized by X-ray diffraction (XRD), magnetic field-dependent resistivity, and ferromagnetic resonance (FMR). XRD was used to confirm uniform bilayer thicknesses. The magnetic field-dependent resistance measurements indicated the presence of magnetoresistance in the deposited films. An as-deposited film with a bilayer thickness of 75 Å demonstrated a roomtemperature magnetoresistive effect of 0.15 %. FMR has been used to determine the relationship between NiFe magnetism and the observed magnetoresistance.
Microhardness, Structure, and Composition Study of Amorphous Hydrogenated Boron Carbide
Authors: Lin Shu-Han , Li Dong , Feldman Bernard J. 
Published: April 2011

ABSTRACTWe have grown amorphous hydrogenated boron carbide thin films by rf plasma decomposition of diborane and methane. The chemical composition, infrared absorption, optical absorption, and microhardness of these thin films were measured. As a function of increasing diborane concentration in the feedstock, we observe increasing boron and hydrogen concentrations, increasing infrared absorption at 1330 cm−1 due to boron icosahedra, increasing optical bandgaps, and an unchanging microhardness in the grown films. The microhardness should have decreased due to the increasing hydrogen concentration; this expected decrease may have been balanced by an increased microhardness due to the boron icosahedra.
Stress in Thin Diamond Films on Various Materials Measured by Microraman Spectroscopy
Authors: Ralchenko V. G. , Obraztsova E. D. , Korotushenko K. G. , Smolin A. A. , Pimenov S. M. , Pereverzev V. G. 
Published: April 2011

ABSTRACTMicroRaman spectroscopy has been used to determine residual stress in polycrystalline diamond films grown by CVD process in a DC arc plasma from CH4/H2 gas mixtures. A variety of substrate materials, including silica glass, Si, SiC, Mo, Cu, Ni, Fe-Ni alloy, WC-Co and steel, were selected in order to extend as much as possible the range of the substrate thermal expansion coefficients (CTE). Diamond adhesion to catalytically active materials (Ni, Fe, Co) and Cu was improved with a thin buffer layer of CVD tungsten. The observed Raman peak shifts were converted to stress values σmeas in the framework of biaxial stress model. Compressive stress has been found in diamond films at all substrates, except SiO2, which provided a tensile stress up to +2.3 GPa. The maximum compressive stress has been detected for Ni substrate σmeas =-11.4 GPa at room temperature and σmeas =-14.3 GPa at T=78 K. A linear dependence of stress on temperature was found at Ni in the temperature range 78–520 K, in good agreement with prediction of thermal stress model. The splitting of diamond peak to singlet and doublet becomes observable at σ>8–9 GPa. The measured stress correlates in general with calculated thermal stress, increasing with CTE value of respective substrate materials, copper being the only exclusion because of its high plasticity.
Adhesion and Young's Modulus of CVD Diamond Thin Films Grown Over Various Substrates
Authors: Ramesham R. , Askew R. F. , Rose M. F. 
Published: April 2011

ABSTRACTDiamond films were deposited by microwave plasma CVD using H2 and CH4 gas mixture over various substrate materials such as Si, Pd, Be, Cu, Mo, AIN, SiO2, Si3N4, Al2O3, Sapphire, Quartz, Ni-base alloys, single crystal Ni, boron nitride, and Ti. We have used a Z-axis pull stud test to determine adhesion strength of diamond film to some of the substrates. Our observations on the adhesion of diamond films to the above substrates are reported. A method will be described to evaluate Young's modulus of CVD diamond films using fabricated diamond cantilever beams.
Diamond {111} Surface: Graphitization or Reconstruction?
Authors: Jungnickel G. , Porezag D. , Frauenheim Th. , Lambrecht W. R. L. , Segall B. , Angust J. C. 
Published: April 2011

ABSTRACTThe reconstruction of the diamond {1111} surface is re-examined by means of density functional theory based tight-binding molecular dynamics. Evidence is found for competition between a graphitizing tendency leading to an unreconstructed but relaxed 1 × 1 surface and a π-bonded chain-like 2 × 1 reconstruction. The implications of the possible co-existence of these two distinct surface phases for diamond growth are discussed.
Diamond-Like Carbon Films for Silicon Passivation in Microelectromechanical Devices
Authors: Houston M. R. , Howe R. T. , Komvopoulos K , Maboudian R. 
Published: April 2011

ABSTRACTThe surface properties of diamond-like carbon (DLC) films deposited by a vacuum arc technique on smooth silicon wafers are presented with specific emphasis given to stiction reduction in microelectromechanical systems (MEMS). The low deposition temperatures afforded by the vacuum arc technique should allow for easy integration of the DLC films into the current fabrication process of typical surface micromachines by means of a standard lift-off processing technique. Using X-ray photoelectron spectroscopy (XPS), contact angle analysis, and atomic force microscopy (AFM), the surface chemistry, microroughness, hydrophobicity, and adhesion forces of DLC-coated Si(100) surfaces were measured and correlated to the measured water contact angles. DLC films were found to be extremely smooth and possess a water contact angle of 87°, which roughly corresponds to a surface energy of 22 mJ/m2. It is shown that the pull-off forces measured by AFM correlate well with the predicted capillary forces. Pull-off forces are reduced on DLC surfaces by about a factor of five compared to 10 nN pull-off forces measured on the RCA-cleaned silicon surfaces. In the absence of meniscus forces, the overall adhesion force is expected to decrease by over an order of magnitude to the van der Waals attractive force present between two DLC-coated surfaces- To further improve the surface properties of DLC, films were exposed to a fluorine plasma which increased the contact angle to 99° and lowered the pull-off force by approximately 20% over that obtained with as-deposited DLC. The significance of these results is discussed with respect to stiction reduction in micromachines.
Mechanical Properties of Amorphous Hard Carbon Films Prepared by Cathodic ARC Deposition
Authors: Anders Simone , Anders André , Ager Joel W. , Wang Zhi , Pharr George M. , Tsui Ting Y. , Brown Ian G. , Bhatia C. Singh 
Published: April 2011

ABSTRACTCathodic arc deposition combined with macroparticle filtering of the plasma is an efficient and versatile method for the deposition of amorphous hard carbon films of high quality. The film properties can be tailored over a broad range by varying the energy of the carbon ions incident upon the substrate and upon the growing film by applying a pulsed bias technique. By varying the bias voltage during the deposition process specific properties of the interface, bulk film and top surface layer can be obtained. We report on nanoindentation and transmission electron microscopy studies as well as stress measurements of cathodic-arc amorphous hard carbon films deposited with varied bias voltage. The investigations were performed on multilayers consisting of alternating hard and soft amorphous carbon.
A Comparative Study of Residual Stresses and Microstructure in a-tC Films
Authors: Martínez-Miranda L. J. , Sullivan J. P. , Friedmann T. A. , Siegal M. P. , Mercer T. W. , Dinardo N. J. 
Published: April 2011

ABSTRACTWe compare the microstructure of highly tetrahedrally-coordinated-amorphous carbon (atC) films prepared by pulsed laser deposition (PLD), measured using both small angle x-ray scattering (SAXS) and x-ray reflectivity, with other physical properties such as film stress and electrical resistivity. These properties are controlled by the film growth conditions and film thicknesses. Films prepared under vacuum conditions exhibit a shift in the measured mass density, as a function of laser energy density. The density for films approximately 600Å thick approach that of crystalline diamond. The measured densities for thicker, approximately 1000Å films, exhibit a smaller shift, and a lower density value. This shift correlates to observed changes in film stress and electrical resistivity. The small angle signal of the reflectivity spectra suggests the presence of layering, or in-plane density variations or a combination of both within the films.
The Effect of Temperature on the Deformation of Diamond Surfaces
Authors: Brookes Chris A. , Brookes E. J. , Xing G. 
Published: April 2011

ABSTRACTA brief review is given of recently published work on the fracture and plastic flow of natural and synthetic diamond crystals when deformed by softer impressors at elevated temperatures. Under these conditions, a brittle-ductile transition (BDT) temperature for the different types of diamond has been established.In this paper we show that below the BDT temperature, brittle ‘chatter’ cracking on {111} cleavage planes accounts for anisotropic wear provided that the mean contact pressure exceeds about 10 GPa. Above the BDT temperature, titanium diboride sliders develop contact pressures sufficient to cause extensive plastic deformation of the diamond specimens but insufficient to produce cleavage fracture. However, repeated sliding with TiB2 does lead to cumulative plastic flow preceding fatigue type fracture on {110} planes. Using cubic boron nitride and diamond sliders above the BD T temperature leads to a combination of both plastic deformation and {110} cracking. The coefficient offriction is a maximum in <100> and a minimum in <110> directions. and the measured scratch hardness, which confirms that the <100> directions are softer than <110>, is shown to be consistent with the predictions of a resolved shear stress model which was de velopedffor explaining anisotropy in all crystals.
1D and 2D Monte Carlo Simulations of Pulsed Laser Ablation Of Si/Ga Into Ar/O2With A Substrate
Authors: Capewell D. L. , Goodwin D. G. 
Published: April 2011

AbstractThe Direct Simulation Monte Carlo (DSMC) method is applied to the problem of pulsed laser deposition in both 1D and 2D axisymmetric simulations. A source of target atoms expands into a cylindrical volume containing a background gas at room temperature and pressures up to 100 mTorr in the presence of a diffusely reflecting substrate. At regular intervals, the density and temperature of each species are computed. Particle flux and energy per particle incident on the substrate are also monitored as functions of time. The simulation results qualitatively compare well with experimental plume diagnostics, with measured film growth rates as a function of background gas pressure, and with measured changes in film growth stoichiometry resulting from the introduction of a background gas into a two-component PLD system.
High Quality RTCVD Sidewall Spacer Dielectrics
Authors: Miles D. S. , Mirabedini M. R. , Venables D. , Wortman J. J. , Maher D. M. 
Published: April 2011

AbstractRapid thermal chemical vapor deposition (RTCVD) has been investigated as an alternative to low pressure chemical vapor deposition (LPCVD) for formation of sidewall spacer dielectric. Silane (SiH 4 ) and tetraethylorthosilicate (TEOS) were chosen as the silicon gas sources in these studies. Reasonable deposition rates were obtained for RTCVD oxides, oxynitrides and nitrides for use in thin sidewall spacer application. Refractive index and etch rate measurements suggest that oxides deposited with a 2 % flow rate ratio of SiH 4 /N2O and annealed at 900 °C for 10 seconds produces films with excellent structural quality. Refractive index and wet etch rate both exhibit a linear dependence with the gas flow ratio. An increase in deposition pressure decreased the refractive index while increasing the etch rate. Oxide and oxynitride dielectrics formed using SiH 4 had a much superior step coverage over a wide range of aspect ratios than TEOS dielectrics. Dit and breakdown fields for oxides and oxynitrides with 3 atomic % nitrogen were comparable to that of thermal oxide indicating their good electrical quality. The results reported suggest that RTCVD sidewall spacers are a promising candidate for use in future MOSFET devices.
Optimization of Process Parameter and Temperature Uniformity On Wafers For Rapid Thermal Processing
Authors: Tillmann Andreas 
Published: April 2011

AbstractA new strategy based algorithm to optimize process parameter uniformity (e.g.sheet resistance, oxide thickness) and temperature uniformity on wafers in a commercially available Rapid Thermal Processing (RTP) system with independent lamp control is described. The computational algorithm uses an effective strategy to minimize the standard deviation of the considered parameter distribution. It is based on simulation software which is able to calculate the temperature and resulting parameter distribution on the wafer for a given lamp correction table. A cyclical variation of the correction values of all lamps is done while minimizing the standard deviation of the considered process parameter. After the input of experimentally obtained wafer maps the optimization can be done within a few minutes. This technique is an effective tool for the process engineer to use to quickly optimize the homogeneity of the RTP tool for particular process requirements. The methodology will be shown on the basis of three typical RTP applications (Rapid Thermal Oxidation, Titanium Silicidation and Implant Annealing). The impact of variations of correction values for single lamps on the resulting process uniformity for different applications will be discussed.
Rapid Thermal Chemical Vapor Deposition of Nitrogen-Doped Polysilicon for High-Performance and High-Reliability CMOS Technology
Authors: Sun S. C. , Wang L. S. , Yeh F. L. 
Published: April 2011

AbstractIn this paper, a detailed study is presented for the growth kinetics of rapid thermal chemical vapor deposition (RTCVD) of nitrogen-doped polysilicon using silane and ammonia chemistry. It is found that nitrogen doping has reduced the surface roughness and grain size of the RTCVD polysilicon film. Both the deposition rate and the incubation time of film growth depend strongly on the ammonia to silane flow ratio. We have proposed a novel structure of NICER (Nitrogen Incorporation into CMOS Gate Electrode by in-situ RTCVD). High performance and highly reliable dual gate CMOS can be formed by combining rapid thermal oxidation (RTO) with RTCVD.
N-Channel Mos Transistors below 0.5 μm with Ultra-Shallow Channels formed by Low Temperature Selective Silicon Epitaxy
Authors: Huang P. L. , Seastrand K. , Violette K. E. , Wolf J. , Öztürk M. C. 
Published: April 2011

AbstractIn this paper, we present an application of ultra high Vacuum Rapid Thermal Chemical Vapor Deposition (UHV-RTCVD) to MOSFET channel engineering. MOSFETs were fabricated on ultra-thin (200 Å), moderately doped (l×1017 - 6×1018 cm−3) p-type epitaxial layers selectively grown in active areas defined by standard LOCOS isolation. The selective epitaxy was achieved using a novel Si2H6Cl2/B2H6 process at 800°C and at a total pressure under 30 mtorr. Low thermal budget processing techniques were emphasized to minimize spread in the channel doping profile. Threshold voltages below 0.6 V were obtained. Transistors with effective channel lengths of 0.45 μm exhibit subthreshold slopes from 78 to 92 mV/decade determined by the epitaxial channel doping density. We have found that by using ultra-thin channels, expected transconductance degradation at high channel doping densities can be minimized. Furthermore, ultra-thin channels help reduce the sensitivity of the threshold voltage on substrate bias. The results show that low temperature selective silicon epitaxy can be used to form ultra-shallow channel doping profiles that can enhance the performance of MOSFETs in the deep submicron regime.
Formation of Raised Source/Drain Junctions by Rapid Thermal Chemical Vapor Deposition
Authors: Öztürk Mehmet C. , Wortman Jimmie J. 
Published: April 2011

AbstractIn this paper, we present alternative uses of rapid thermal chemical vapor deposition (RTCVD) in forming junctions for the raised source/drain MOSFET. The results will include applications of epitaxial silicon, SixGe1−x and TiSi2 all selectively deposited in dedicated coldwalled, lamp heated high or ultra high vacuum RTCVD reactors. Two general approaches will be considered : 1) ultra shallow junction formation in silicon followed by a selective deposition process to form a raised contact, 2) selective deposition to obtain a layer that can be used as a solid diffusion source and as a sacrificial layer for self-aligned silicide formation. In the first approach, junctions are formed typically by low energy ion-implantation. In this paper, we present rapid thermal vapor phase doping (RTVPD) as an alternative to ion-implantation to form defect free ultra-shallow junctions in Si. The method involves exposing a silicon wafer to a dopant gas (such as B2H6) at a moderate temperature (∼600°C) for a short time and subsequent annealing for drive-in. This is followed by either selective epitaxy and conventional self-aligned TiSi2 formation or selective deposition of a low-resistivity C54 TiSi2 from TiCl4 and SiH4. In the second approach, first, a semiconductor (Si, polysilicon or SixGe1−x) is deposited selectively. If the material is undoped, doping can be achieved by ion-implantation. In-situ doping is also possible as will be shown with p- and n-type SixGe1−x at temperatures as low as 625°C using B2H6 or PH3. The doped layer is then used as a solid diffusion source to form the junctions by out-diffusion. Using these different approaches, we present examples of high quality junctions in Si as shallow as a few hundred angstroms. The techniques are compared based upon their robustness, complexity, equipment and thermal budget requirements.
Rapid Thermal Transformation of A-15 Crystal Structure Metallic Thin Films
Authors: O'Keefe M. J. , Cerny C. L. 
Published: April 2011

AbstractPhysical vapor deposition of Group VI elements (Cr, Mo, W) can lead to the formation of a metastable A-15 crystal structure under certain processing conditions. Typically, a thermally induced transformation of the metastable A-15 structure into the equilibrium body centered cubic structure has been accomplished by conventional furnace annealing at T/Tm≈ 0.3 from tens of minutes to several hours. In this study we report on the use of rapid thermal annealing to transform sputter deposited A- 15 crystal structure tungsten and chromium thin films into body centered cubic films within the same temperature range but at times on the order of one minute. The minimum annealing times and temperatures required for complete transformation of the A-15 phase into the BCC phase varied from sample to sample, indicating that the transformation was dependent on the film characteristics. The electrical resistivity of A-15 Cr and W films was measured before and after rapid thermal annealing and was found to significantly decrease after transformation into the body center cubic phase.
RTP Based Tin Barrier Integrity for WF6 Processing During W-Plug Formation
Authors: Lee C. Y. , Yen H. , Hsia S. T. , Liu D. , Shah N. , Feldmeier K. , Wasserman Y. 
Published: April 2011

AbstractThe study evaluates the barrier integrity of Rapid Thermal Processed (RTP) titanium layer to form TiSi2/TiN and sputter deposited TiN layer annealed in RTP system. Various temperatures and ambient conditions were used during processing. Subsequent effects of the W-plug process on the TiN layer have been evaluated in terms of effects of WF6 on the underlying Ti/TiN layer.Evaluation of the WF6 on the via side walls and the via corners will be the primary focus of this work. Results will be discussed in terms of effective TiN thickness the process of formation of TiN and its stability