bluuebunny/crossref_metadata_2025 huggingface dataset:
An Extensible Software Design Applied to Rapid Thermal Processing
Authors: Dankoski Paul , Gyugyi Paul , Franklin Gene
Published: March 2011

The next five to ten years will show a dramatic increase in the number of sensors and actuators in use. Several advances in technology, namely integrated sensors, fast reliable communications, and powerful computers, are making such changes possible. Coordinating the complex interactions of multiple sensors and control settings can be too confusing for an ad-hoc approach. Applying modern model-based control theory to multi-input/multi-output systems has the potential of improving the yield and throughput in a computer integrated manufacturing environment.

Our expectation is that as more sensors and actuators become available, it will be important to handle internal communications between processing subsystems in a uniform manner to allow for incremental expansions to the processing equipment. Because of the wide assortment of physical sensors available for control equipment, an architecture is presented which attempts to unify the communications and control in a multiprocessor environment. The focus of this paper will be to explain one method of controlling a Rapid Thermal Multiprocessing chamber and how it is designed to handle future growth.

The implementation and experimentation are being performed on the Rapid Thermal Multiprocessor (RTM) at the Center for Integrated Systems (CIS) at Stanford University.
Combined Simulation and Measurement Study of Temperature Uniformity in Rapid Thermal Processing
Authors: Lin Yur-Tsai , Subrahmanyan Ravi , Sitaram A. R.
Published: March 2011

Modeling and simulation of rapid thermal processing has been studied extensively in the past. This work presents the results of a combined simulation and measurement study of a commercial multilamp RTP chamber. The simulations were used to estimate the contributions of different geometrical, material, process, and physical effects on temperature uniformity. The physical effects considered in the simulations included radiation, thermal conduction, transient effects during ramp up and cool down and the effects of patterns on the wafer surface. The effects were corroborated by direct temperature measurements using thermocouple embedded wafers, and the results were used to reliably calculate stress effects. The stress distributions were determined analytically in cases without surface films on the wafer. In the case of wafers with surface films, stress distributions were calculated based on thermal strains. This study allows us to concentrate efforts on increasing temperature uniformity to those areas where the greatest benefits in terms of yield and film uniformity can be obtained.
Rta Implant Monitor: Does it Tell the Truth?
Authors: Lojek B.
Published: March 2011

The measurement of the sheet resistance of Arsenic implanted layers is almost exclusively used for the monitoring of temperature nonuniformity of RTP equipment. However, as is shown in this contribution this technique relies on several averaging processes and a satisfactory uniformity of sheet resistance achieved on the implant monitor does not mean that the same performance will be achieved on the wafer with different optical properties. The sheet resistance uniformity is not the only the function of the processing temperature but also the function of the processing parameters such as annealing time, rate of heating and cooling, intensity of radiation and its spectral variation as well as function of the optical properties ofthe processed material. Impact of the substrate on the achieved results and processing dependence are discussed.
Reduced Thermal Budget Borophosphosilicate Glass (BPSG) Fusion and Implant Activation Using Rapid Thermal Annealing and Steam Reflow
Authors: Thar R.P.S. , Gonzalez F. , Hawthorne R. , Ward V. , Jeng N.
Published: March 2011

Highly dense next generation dynamic random access memory (DRAM) devices impose severe restrictions on the times, temperatures and atmospheres of all thermal process steps following the sourcedrain implantation. BPSG reflow and source-drain implant activation are two of the process steps that contribute significantly towards enhanced overall thermal budget during the fabrication of DRAM devices.

In this paper, we present the results of an optimized thermal budget process using a combination of steam reflow and rapid thermal annealing (RTA). We demonstrate that this approach produces better reflow characteristics than the best RTA or reflow cycle alone. The processes will be compared on pchannel CMOS devices and the differences in various electrical characteristics will be highlighted. The results of BPSG reflow and dopant outdiffusion will be presented. Experimentally obtained data on junction depth from SIMS analysis will be correlated with corresponding RTA simulation results.
High Quality Ultra-Thin Tunneling N2O Oxides Fabricated by Rtp
Authors: Yoon G. W. , Joshi A. B. , Kim J. , Kwong D. L.
Published: March 2011

In this paper, a detailed reliability investigation is presented for ultra-thin tunneling (∼50 Å) oxides grown in N2O ambient using rapid thermal processing (RTP). These N2Oss-oxides are compared with oxides of identical thickness grown in O2 ambient by RTP. The reliability investigations include time-dependent dielectric breakdown as well as stress-induced leakage current in MOS capacitors with these gate dielectrics. Results show that ultra-thin N2O-oxides show much improved reliability as compared to oxide grown in O2 ambient.
Fabrication of Ultra-Shallow P+-N and N+-P Junctions by Diffusion From Selectively Deposited, Ion-Implanted and In-Situ Doped Si0.7Ge0.3
Authors: Grider D.T. , ÖztÜrk M.C. , Wortman J.J. , Harris G.S. , Maher D.M.
Published: March 2011

Selectively deposited Si0.7Ge0.3 has been investigated as a potential diffusion source for fabricating ultra-shallow junctions in Si. Rapid thermal chemical vapor deposition (RTCVD) was used to selectively deposit Si0.7Ge0.3 on Si using SiH2C12, GeH4, and H2. Both ionimplanted and in-situ doped Si0.7Ge0.3 were considered as a diffusion source for fabricating ultra-shallow junctions. In-situ doping was achieved with B2H6 and PH3 for p-type and n-type doping, respectively. Boron and phosphorus diffusion in ion-implanted Si0.7Ge0.3 was investigated and modeled using SSUPREM4. Diffusion from implanted and in-situ doped Si0.7Ge0.3 in Si was also studied and modeled. Boron diffusivities in Si0.7Ge0.3 were found to be approximately 10 times greater than in Si, while phosphorus diffusivities were over 100 times greater in Si0.7Ge0.3. The faster dopant diffusivities in Si0.7Ge0.3 allow high surface concentration, abrupt diffusion profiles to be formed in Si. Gated, p-n junction diodes with junction depths as shallow as 140Å were fabricated and tested to study the quality of the diffusions from Si0.7Ge0.3.
Fabrication of High Quality Mos Devices for Application in Hazardous Environments Based on Rtp Gate Dielectrics With in Situ Rtcvd of Polysilicon Gates
Authors: Fröschle B. , Bruemmer H.P. , Lang W. , Neumeier K. , Ramm P.
Published: March 2011

Process modules for MOS gate fabrication were developed which can be completed subsequently in one RTP reactor: atmospheric process sequences for gate oxides and oxynitrides as well as low pressure chemical vapor deposition of polysilicon (RTCVD). Prior to the Rapid Thermal Oxidation (RTO), the wafers were treated with a Rapid Thermal Cleaning process (RTC) in H2/Ar ambient. After the desoxidation step the RTO was done in O2/H2/Ar followed by an anneal (RTA) for the gate oxide or a nitridation in NH3 (RTN) and reoxidation for the oxynitrides, respectively. The polysilicon gate electrode was fabricated either by RTCVD in situ or in a conventional furnace reactor. The two-step RTCVD process resulted in a very good thickness uniformity for the polysilicon layers of 3% (3mm from the edge). The influence of the process variations on breakdown field, fixed oxide charge, interface state density, flatband voltage, and threshold voltage of the different types of gate dielectrics was investigated. The charges and voltages were determined by LF-HF CV measurements. In order to characterize the radiation tolerance of electronic devices, radiation induced flatband and threshold voltage shifts as well as the build up of interface charges were determined. The irradiation was performed at a Co - 60 gamma source. Breakdown fields in the range of 19 MV/cm, interface state densities of less than 109 eV−2cm−2, and radiation induced threshold voltage shifts below 0.1 V after 1.5 Mrad(Si) were obtained.
Improved Passivation of Silicon Solar Cells Using Combined Low-Energy Hydrogen Implantation and Optical Processing
Authors: Sopori Bhushan L.
Published: March 2011

An improved technique for impurity/defect passivation of silicon solar cells is described. A low-energy hydrogen implantation is performed from the back side of solar cells to produce a deep hydrogen diffusion. The deep diffusion is believed to be caused by the formation of a mobile hydrogen-vacancy (H-V) complex. Next, a layer of Al is deposited on the hydrogenated side and an Optical Processing (OP) step is performed. The OP step accomplishes several objectives that include formation of an ohmic contact, dissociation of H-V complexes to release hydrogen that can participate in further passivation, and dissolution and regrowth of the highly defected surface layer.
Improving The Barrier Properties of Nickel. Chrome and Nichrome Films on Silicon
Authors: Nowicki Ronald S. , Arias Louie , Rau Chris , Motamedi Ahmad , Harris David W. , Baumann Scott
Published: March 2011

A new technique for improving the diffusion barrier properties of thin, thermallyevaporated nickel, chromium and nichrome films on silicon is described. In this technique, known as “Rapid Thermal Annealing” (RTA), profound differences in the diffusion barrier properties of the films annealed in ammonia ambient at 550-750°C, in comparison to films annealed only in vacuum, were observed. The films annealed in ammonia retained their integrity while the films annealed in vacuum showed diffusion of the silicon into the metal overlayer throughout the entire thickness of the metal in some cases. The film sheet resistance increase for the latter was consistent with the formation of the metal silicide. The possibility of extending this technique to electroplated films used in integrated and hybrid device fabrication is being studied.
A Low Frequency Remote Plasma Rapid Thermal CVD System with Face Down Electrostatic Clamp Wafer Holder
Authors: Bonfim Marlio J. C. , Swart Jacobus W. , Velasco Cristian E. M. , Okura Juscelino H. , Verdonck Patrick B.
Published: March 2011

A multiprocess CVD system with the following main features is designed and constructed: the wafer holder is made of a Si wafer with diameter larger than the process wafers. This larger holder produces a better temperature uniformity on the process wafer. A good thermal contact between holder and process wafer is obtained by an electrostatic clamp. The holder supports the process wafer facing down. A remote plasma is produced in a small chamber inside the process chamber. The 100 KHz RF frequency keeps the system very simple and cheap while still reasonable ionization is achieved. SiO2 films were deposited using SiH4 and O2 with and without remote plasma of O2. At low temperatures and 1.5 Torr, process activation energies of about 0.9 and 0.3 eV were obtained respectively.
Modelling the Dielectric Growth on Silicon Produced in a Nitrous Oxide Rtp Environment
Authors: Harrison H Barry , Dimitrijev Sima , Sweatman Denis , Parker Joanna , Preston Stephanie
Published: March 2011

The results of measurements of the physical properties of the dielectric grown on various orientations and surface doping concentration on silicon in an N2O environment are presented. We use this data to produce a model that predicts the dielectric thickness as a function of time and temperature.
Computer Simulation of Chain Molecule-Inorganic Interphases: Chromatographic Stationary Phases and Rigid Rod Self-Assembled Monolayers
Authors: Klatte S. J. , Zhang Z. , Beck T. L.
Published: March 2011

Molecular dynamics simulations of alkane chains chemically tethered to silica surfaces are presented. The system was modeled after the stationary phases of chromatographic columns. The interphase properties were computed as functions of chain length, surface bonding density, and temperature. At densities appropriate for chromatography, the chains undergo a gradual transition with increasing temperature from a glassy state to a liquid-like state. The simulations are consistent with extensive experimental data including neutron scattering, NMR, IR, and EPR methods. The implications for chromatographic retention are discussed. In a second series of studies, we explored driving forces for observed ordering on the solid surface in terms of the various components of the chain-chain and chain-surface forces. Interfacial z profiles are sensitive functions of each of the forces. Finally, we present preliminary Monte Carlo results on origins of tilt behavior in self assembled monolayers of rigid chain species on metal surfaces.
Formation of Ultrathin Polystyrene Films in Adsorbed Surfactant Bilayers on Silica
Authors: O'Haver John H. , Harwell Jeffrey H. , O'Rear Edgar A. , Waddell Walter H. , Snodgrass Linda J. , Parker James R.
Published: March 2011

Adsorbed surfactant bilayers on silica are proposed as the reaction site for the formation of ultrathin polystyrene films. Results from the polymerization of styrene in cetyl trimethyl ammonium bromide bilayers show effective conversion of adsolubilized monomer to polymer. The process has been demonstrated for a variety of precipitated silica substrates and for two types of initiation schemes. The polymer formed has been extracted and characterized using PA-FTIR, NMR, UV, and GPC. The molecular weight of polymer formed has also been investigated with respect to polymerization time.
Surface-Enhanced Raman Scattering as an In-Situ Probe of Polyimide/Silver Interphases
Authors: Young J. T. , Boerio F. J.
Published: March 2011

The molecular structure of interphases formed between thin films of the polyamic acid of pyromellitic dianhydride (PMDA) and oxydianiline (ODA) and silver substrates that were pretreated with m-aminothiophenol (m-ATP) was determined using surface enhanced Raman scattering (SERS) and X-ray photoelectron spectroscopy (XPS). It was found that m-ATP adsorbed dissociatively onto silver substrates through the thiol groups. When thin films of the polyamic acid of PMDA/ODA were spin-coated onto the silver substrates treated with m-ATP, an interphase that was only a few angstroms in thickness was formed in which acid groups of the polyamic acid and amino groups of the m-ATP combined to form ammonium carboxylate species. The bulk of the polyamic acid films was cured to polyimide by immersion in mixtures of acetic anhydride and pyridine or triethylamine but ammonium carboxylate species inhibited curing in the interphase.
The Use of a Single-Fiber Fragmentation Test to Study Environmental Durability of Interfaces/Interphases Between Epoxy and a Glass Fiber
Authors: Schuute Carol L. , McDonough Walter , Shioya Masatoshi , Hunston Donald L.
Published: March 2011

This work examines the usefulness of the single-fiber fragmentation test in studying the durability of fiber/matrix interfaces/interphases. This test measures the critical length/diameter ratio (L/D) of the fiber fragments formed in the test and relates this length to the interface's strength, or ability to transfer load. In the work reported here, we immersed samples of epoxy containing a single-glass fiber - that was previously sized with an epoxy-compatible coating - in either 65 or 75 °C water and tested after different times of exposure. In general, this ratio increased as a function of time of exposure to water. During exposure at 75 °C, the fibers' L/D in the samples did not increase significantly until after the sample reached its “apparent” equilibrium content of water ∼ (3.0 wt%). Because there was no significant measurable change in the tensile modulus between wet and dry samples, we cannot attribute these differences in L/D to changes in the resin's properties due to plasticizing by water. A small percentage of samples exposed at 65 °C did not show a significant increase in L/D, and in these cases the moisture produced a marked roughening of the fiber surface along the fiber/matrix interface. One possible explanation is that the attack by moisture degrades the interface, thus reducing its strength with a corresponding increase in the L/D. To varying degrees, however, the attack by moisture also degrades the E-glass fiber. This attack by moisture roughened the surfaces of the fibers and increased the distribution and/or size of the critical flaws, thus reducing both the strength of the fiber and the L/D. Based on our preliminary results, it appears that the singlefiber test has the potential to be useful for studying the durability of the resin/matrix interface providing that the influence of the environmental agent on all of the components of the model composite: resin, fiber, and interface/phase, is considered.
Density Functional Calculations on the Metal-Polymer Interfaces
Authors: Selmani A. , Ouhlal A. , Yelon A.
Published: March 2011

Bonding of chromium to the polyimide, PMDA-ODA, surface is still subject to debate. In an attempt to clarify this problem, we have performed density functional theory calculations on a model molecule, phthalimide, which contains the most reactive functionalities of the polyimide PMDA part. Considering only the low spin case, we find that chromium bonds preferentially to the phenyl ring. However, when we release the spin polarisation and optimise the structure, we find that the absolute stable configuration is that of chromium in a quintet state at a carbonyl group. The energy difference is 0.30 eV. The complete optimised structures are determined. The infrared spectrum have been calculated for phthalimide and compared to experimental spectra. The agreement is excellent. A vibrational analysis for the Cr/phthalimide system, in both configurations (Cr on C=O and Cr on phenyl), in their stable spin states, is presented.
Surface Modification of Polytetrafluoroethylene and the Deposition of Copper Films
Authors: Jiang Wenbiao , Norton M. Grant , Dickinson J. Thomas
Published: March 2011

Enhancement of the adhesion of thin copper films on polytetrafluoroethylene substrates was found when the substrate surface was irradiated with a pulsed UV excimer laser prior to metal deposition. The interaction between the laser and the polymer was examined by characterizing the neutral and charged species emitted from the surface during irradiation. The nature of the species emitted indicates that significant chemical modification of the polymer surface occurs. In addition to chemical modification, the interaction with the laser also alters the surface morphology of the polymer. Irradiation at fluences of ∼ 0.6 J/cm2 results in an overall planarization of the surface, whilst irradiation at higher fluences results in the formation and enlargement of voids and localized melting.
Glass-Coated, Surface-Modified High-Performance Polymer Fibers
Authors: Lietzaua Christian , Farris Richard J.
Published: March 2011

High-modulus PPTA and PBZT fibers have been surface-modified by a series of reactions to allow single filaments to be wetted by sodium silicate solutions as well as to exhibit good adhesion to the resulting glass coating. Fiber surfaces have been characterized by X-ray photoelectron spectroscopy. PBZT and PPTA fibers showed little or no decrease of their tensile properties as a consequence of the surface-modification. Glass coatings have been applied to single filaments by dip-coating in an aqueous sodium silicate solution followed by air- and vacuumdrying. Coated PPTA and PBZT fibers with shear moduli as high as 5 GPa have been prepared. The compressive strain at failure of PPTA filaments coated with a 0.5 μm thick air-dried coating was raised to 0.6%, compared to 0.4% for uncoated filaments.
Profiling Polyimide-Polyimide Interfaces
Authors: Stoffel Nancy C. , Kramer Edward J. , Volksen Willi , Russell Thomas P.
Published: March 2011

The adhesion of spuncast polyimide layers is critical to the success of manufacturing multilayer polyimide structures. We have measured the interpenetration between a spuncast layer of the meta isomer of poly(amic ethyl ester) (PAE) precursor of PMDA 4,4′ ODA and the corresponding partially-imidized PAE base layer using forward recoil spectrometry (FRES). Measurements made with FRES show that interpenetration decreases rapidly as the base layer imide fraction f increased, with a corresponding decrease in adhesion measured with a T-peel test. In the region of f > 0.8, differences in interfacial adhesion are still observed while the interfacial widths are too narrow to be differentiated with FRES. For this reason, the use of other high resolution techniques for profiling the polyimide-polyimide interface such as nuclear reaction analysis, dynamic secondary ion mass spectrometry, and neutron reflectometry will be necessary to accurately correlate interpenetration with adhesion.
Aluminum Oxide Films for Thermo-Oxidative Protection of Polyimide-Based Composites
Authors: Miller Larry M. , Gulino Daniel A.
Published: March 2011

Polyimide-based composites offer one of the best opportunities to bring the advantages of high modulus-to-density ratio materials to higher temperature applications, such as jet engines. In the present work, thin films (1000 - 2000Å) of aluminum oxide have been deposited by plasma-enhanced chemical vapor deposition from aluminum triisopropoxide precursor on polyimide composite substrates. The films were characterized for stoichiometry, thickness uniformity, and adhesion, and their effectiveness in the prevention of thermo-oxidative degradation of the composite at temperatures up to 371 °C has been examined and compared to that provided by other thin film materials. These preliminary results indicate that Al2O3 is not as successful as SiO2 at preventing oxidative degradation, although significant variability in the quality of the polyimide composite substrate makes precise comparison difficult.
Environmental Effects on the Mechanical Behaviour of Thermoplastic Toughened Phenolics
Authors: Eccott A. R. , Arnold J. C. , Isaac D. H.
Published: March 2011

The environmental stress cracking (ESC) behaviour of thermoplastic toughened phenolics has been studied. As these materials have applications for ‘under the bonnet’ automotive components, testing took place in several ‘in - service’ environments and in some of the constituent chemicals as well as in air.

Initial screening of the materials using three point bend testing highlighted the most hostile environments for further study. More detailed creep tests were then performed with methanol and air. ESC effects led to an increase in creep rate which relates to crack initiation. Crack initiation is lowest at intermediate levels of thermoplastic with an optimum content of about 12%. It was found that there was a significant decrease in the creep rupture lifetimes as the fraction of thermoplastic toughening agent increased. With low thermoplastic content, crack blunting becomes an important factor.
Optical Measurement of Preform Impregnation in Resin Transfer Molding
Authors: Nowak Thomas , Chun Jung-Hoon
Published: March 2011

Infiltration of preforms used to manufacture high-performance, advanced polymer composites can lead to void formation due to inhomogeneities within the preforms. Void formation occurs at three distinct length scales: the fiber, tow and part scales. Flow visualization experiments were used to characterize void formation at the tow and fiber scales. Effects of tow-scale inhomogeneities were studied by varying the warp angle of a woven fabric. Effects of fiber-scale inhomogeneities were studied using scale models of typical tows. The experiments indicate that minimization of void content requires a trade-off between fiberscale and tow-scale void formation.
Graphite Fiber/Polyimide Composites with Improved Processability
Authors: Delvigs Peter , Klopotek David L. , Cavano Paul J.
Published: March 2011

In an effort to improve the processing characteristics of addition-type polyimide matrix resins, the use of flexibilized three-ring and four-ring aryl diamines was investigated. A series of fourteen diamines containing carbonyl and methylene, as well as thio connecting groups was synthesized. The diamines were polymerized with the dimethyl ester of 3,3,′4,4′-benzophenonetetracarboxylic acid, using the monomethyl ester of nadic acid as an end cap. The effect of diamine structure on the solubility and rheological properties during cure, as well as glass transition temperature and thermooxidative stability of neat resins was determined. Graphite fiber-reinforced composites were fabricated from selected resin formulations, and composite thermomechanical properties were investigated.
Photosensitive Polyamic Acids Developable with Aqueous Alkaline Solutions
Authors: Tanaka Jun , Kikkawa Haruhiko , Shoji Fusaji , Satou Hidetaka , Kataoka Fumio
Published: March 2011

New negative-type photosensitive polyamic acids, precursors of polyimides, developable with aqueous alkaline solutions were synthesized. Among diamine monomers having a photofunctional group, 2′-(methacryloyloxy)ethyl 3,5-diaminobenzoate yields high molecular weight polyamic acids. A photosensitive polymer composition consisting of Michler's ketone and a thermally stable peroxide, 3,3′,4,4′-tetrakis(t-butyldioxycarbonyl)-benzophenone, results in high photosensitivity. The photosensitive coating of the composition is soluble in aqueous alkaline solutions as well as in organic aprotic polar solvents and either can be used as a developer of the coating. However, resolution of the patterns is quite different especially with thick films. Solvent developers result in poor resolution whereas aqueous alkaline developers give patterns of high aspect ratio even with thick films. This is probably due to the difference in the diffusion efficiency and swelling property of the polymer to the developers.

Effects of copolymerizing with an ordinary diamine monomer on photosensitivities and film properties of the polyimides derived from their precursors are also discussed.
Multilayer Mirrors For X-Ray Lithography
Authors: Spiller Eberhard , Watson IBM T. J.
Published: March 2011

The applications of multilayer x-ray mirrors to x-ray lithography are reviewed. Topics included are: multilayer performance and characterization, testing and fabrication of large mirrors with figure errors in the Angstrom range, multilayer x-ray masks, and collimators.
Top Layer Oxidation In Mo/SI Multilayer X-Ray Mirror
Authors: Nguyen Khanh , Gullikson Eric , Underwood James
Published: March 2011

Reflectivity of Mo/Si multilayer x-ray mirrors with molybdenum as the top layer decreased over time when stored in air due to oxidation of the top Mo layer to MoO3 and MoO2. High reflectivity can be maintained by having silicon as the top layer. In fact, reflectivity of Si-top multilayer coatings increase slightly during the first few days after deposition.
Fast Dosimeter Film For Evaluation Of X-Ray Lithography Sources
Authors: Maldonado Juan R. , Pomerene Andrew
Published: March 2011

This paper presents data on the soft x-ray behavior of the photochromic dosimeter film UVSC manufactured by Sensor Physics. In particular, the x-ray sensitivity measured with synchrotron storage ring x-ray sources will be presented and compared with a presently used dosimeter film which is many times less sensitive. Relevant properties of the film for x-ray source evaluation also will be presented together with data obtained with other x-ray lithography sources.
Characterization Of Boron Films Prepared By Chemical Vapor Deposition And Their Application In X-Ray Imaging
Authors: Yuan Fang , Allred David D.
Published: March 2011

Boron, a low Z element, is useful for x-ray optics since it has a low atomic absorption coefficient. Boron films prepared by chemical vapor deposition were characterized optically, electronically and mechanically. Auger, infrared and hydrogen effusion analyses showed that the films are amorphous hydrogenated boron. The hydrogen content ranges from 8–71%. The measurements of the complex refractive index and the resistance vs. temperature determined that they are a typical amorphous semiconductor with the energy gap ranging from 1.09 to 1.36 eV, decreasing with increasing hydrogen content and with the Fermi energy level pinned about midgap. The real refractive index at 490 nm increases from 3.25–3.59 with increasing hydrogen content. The Young's modulus and hardness were found to be 3.05 × 1013 dyne/cm2 and around 2500 Vickers, respectively. The chemical tests suggested that boron films are stable in nonoxidizing bases and concentrated acids. Some oxidizing bases such as basic ferricyanide and permanganate solutions are good etchants for CVD boron films. Boron coated beryllium x-ray windows which have enhanced resistance to degradation are now commercially available, and self-supporting boron windows are potential future products for x-ray imaging.
Ionization Radiation Effects And Mechanisms
Authors: Vladimirsky Yuli , Scott John D. , Bhattacharya Pradeep K.
Published: March 2011

A systematic approach for predicting radiation stability of materials and devices is presented. The conceptual basis is a consideration of the radiolysis potentially occurring in x-ray-irradiated materials as a multi-stage process: a) primary radiation excitations (PRE); b) secondary generation of isolated electronic and structural defects resulting from PRE relaxation; and c) interaction, accumulation, and coagulation of defects resulting in change of device electronic properties and in degradation of optical material. This predictive technique involves specific relevant information in a relatively simple context for the purpose of modeling the radiolysis process. It should find general application in selecting materials for x-ray optical elements such as masks, filters, windows where resistance to radiolysis is required as well as for photoresists where radiolytic sensitivity is necessary.
LPCVD Of Silicon Carbide Films From The Organosilanes Diethylsilane And Di-T-Butylsilane
Authors: Levy Roland A. , Grow James M.
Published: March 2011

In this paper, the kinetics and properties of amorphous LPCVD silicon carbide films synthesized from the single organosilane precursors diethylsilane (DES) or di-tbutylsilane (DTBS) are discussed. For DES, the growth rate is observed to vary linearly with flow rate and pressure, while for DTBS, a square root dependency is seen as a function of these parameters. An Arrhenius type behavior was observed for both chemistries yielding activation energy values of 40 and 25 kcal/mol for DES and DTBS respectively. The elemental composition of the films became progressively richer in carbon as the deposition temperature increased with stoichiometry occurring near 750°C. The film stress was dependent on carbon content and became compressive at compositions near Si0.35C0.65. The hardness and Young's modulus of the films increased with increasing carbon content reaching maxima near stoichiometry. Free-standing membranes produced under optimal processing conditions had a relatively low optical transmission due to excess carbon. Although, transmission characteristics were improved by adding NH3 in the reaction chamber, the resulting silicon carbonitride films exhibited undesirably high values of tensile stress.
Multilayer Membranes For X-Ray Lithography
Authors: Shimkunas Alex R. , Mauger Philip E. , Bourge Lawrence P.
Published: March 2011

Multilayer x-ray lithography membranes were designed and fabricated. Consisting of alternating layers of SiC and SiNx, the membranes were designed to have low reflectance for improved optical alignment of x-ray masks, high fracture strength, superior chemicaletch resistance, and high manufacturing yield. The membranes were prepared from multilayer coatings deposited on silicon wafers in an electron cyclotron resonance chemical vapor deposition system. Membranes with less than 5% reflectance over 150 nm bandwidths were made. External SiNx layers increased the chemical etch resistance of the membranes. The fracture strength was 2–3 times that of SiC, and the membrane yield was 50% higher than that of single-layer SiC. Field-emission SEM of the multilayer coating cross-section showed the presence of 20–150 nm defects near the layer interfaces. The layering confines or stabilizes the defects, thereby increasing the membrane yield and fracture strength.
Effects of Simulated X-Ray Lithography Exposures On Submicron-Channel Mosfets
Authors: Lelis A. J. , Oldham T. R.
Published: March 2011

Investigations of submicron-channel-length n- and p-channel MOSFETs subjected to channel hot-carrier stressing were performed, comparing the reliability of devices with and without exposure to simulated x-ray lithography processing steps. No significant differences were observed between the sample groups.
Contactless Evaluation Of The Stress In X-Ray Mask Wafers (SiN/Si) Using A Laser/Microwave Method.
Authors: Oda Masatoshi , Usami Akira , Nakai Takahisa , Ito Akira , Ichimura Masaya , Wada Takao
Published: March 2011

Highly accurate X-ray masks are strongly required to establish SR lithography technology. X-ray masks must be produced as accurately as the LSI devices, because a one-toone projection aligner system is used. To minimize the in-plane mask distortion, it is desirable to estimate the value of the stress and the non-uniformity in the membrane fabrication (SiN) process. The values of the stress were estimated from the measurement of the warpage and the calculation. It is very difficult to obtain the stress distribution in the SiN/Si wafer. Thus, we measured the minority carrier lifetime distribution using the non-contact laser/microwave method. The carrier injection was done by a 774nm or 904nm semiconductor laser diode, and their beam was focused to about 500 μmφ. The surface lifetime, τ s, of the SiN/Si wafer with the stress over ˜ 108dyn/cm2 decreased to 60–70% of that of the bare Si wafer. Thus, the contactless laser/microwave system can be adaptable for the characterization in the X-ray mask process.
Polycrystalline Diamond Films for X-Ray Lithography
Authors: Whitehair S. J. , Yehoda J. E. , Fuentes R. , Roy R. A. , Guarnieri C. R. , Cuomo J. J.
Published: March 2011

Microwave driven discharges are finding increasing use in semiconductor areas such as deposition, etching, cleaning and ashing. One application that is of particular interest is the use of microwave discharge grown thin film diamond as a x-ray mask. Because of diamonds extreme properties these masks offer potential advantages over current silicon based mask technology. A review of diamond mask technology will be presented and compared to competing technologies.
Synchrotron Radiation for Measurement of Contaminants on Silicon Surfaces
Authors: Madden Michael C. , Wherry David C. , Pianetta Piero , Brennan Sean
Published: March 2011

The detection limit for aluminum using total reflection x-ray fluorescence (TXRF) is approximately 100 times lower for a synchrotron source compared to a conventional source. The detection limit for transition metals is approximately 15 to 40 times lower depending on atomic number and energy of the incident radiation.
X-Ray Analysis of Multilayer Structures
Authors: Kushnir V. I. , Georgopoulos P.
Published: March 2011

A new technique of obtaining layer thickness and internal strains in multilayer structures and quantum wells from the rocking curve data is described and analytically proved. This method consists of Fourier transform of the experimental intensity profile multiplied by the wave vector deviation squared. It is shown that peaks of the Fourier transform correspond to distances between boundaries in the specimen. The (400) reflection curves of a quantum well in InP/InAs and a superlattice structure made up of latticematched GaAs/Ga0.49 In0.51P layers were measured with 8 KeV radiation at beamnline X-18A, National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The results of above procedure were used to reduce a number of degrees of freedom in a computer simulation of reflecting curves. It is shown that it is possible to extract layer thicknesses with the accuracy of about 15 Å for thick layers to as low as 1 Å for superlattices. Interplanar distances can be obtained with an accuracy of 0.0001 Å.
Investigation of Filamentation Damage Resulting from Electromagnetic Breakdown in Si Bi-Polar Diodes
Authors: Wang S. , Dudley M. , Fazi C. , Gordon-Smnith D.
Published: March 2011

Synchrotron white beam X-ray topographic studies of damage induced during the R-F electromagnetic breakdown of bi-polar diodes on silicon have been carried out. Filaments associated with damage processes in reverse bias, have been observed close to the surface of the Si epilayer, using the surface sensitive grazing Bragg-Laue technique. Ray-tracing experiments have enabled us to determine the exact lateral location of the filament to be at the edge of the metallization region, at the junction between it and the metallic contact. The influence of these results on hardening technologies is discussed.
Atomic Structure Studies of Zirconia Solid Solutions by EXAFS
Authors: Chen I-Wei , Li Ping , Penner-Hahn James
Published: March 2011

We have investigated, using EXAFS, the local atomic structures of four zirconia polymorphs and their solid solutions with Ca2+, Ga3+, Fe3+, y3+, Gd3+, Ge4+, Ti4+, Ce4+ and Nb5+. Structural information up to 9Å, and in one special case up to 10.9Å, from the absorbing atom has been obtained. The characteristic features of local environments of both the host Zr and the dopant cations, and their variations leading to cation ordering and symmetry evolutions, are elucidated in terms of a dopant size effect and an oxygen vacancy effect. The dynamic aspects of the EXAFS Debye-Waller factor are used to shed light on the connection between phase transition, dopant stabilization, and cation-anion correlation.
Diffraction of Fe/Cr using Anomalous Dispersion Enhancement
Authors: Foiles C. L. , Loloee R. , Rahman Sharif M.
Published: March 2011

Results for a study using anomalous scattering to increase the X-ray contrast between Fe and Cr in metallic multilayers are reported. This increased contrast is sufficient to provide reliable values for actual bilayer distances and to begin semi-quantitative analysis of peak intensities even in the presence of orientational texture.
Simultaneous, Time-Resolved, Saxs/Waxs Studies on Block Copoly(Ether-Urethane) Phase Behaviour
Authors: Bras W. , Derbyshire G. E. , Greavest G. N. , Mantt G. R. , Naylor S. , Ryan A. J.
Published: March 2011

A new experimental technique for the characterisation of the thermal-morphological properties of materials has been developed at Daresbury. Many thermal events, for example melting endotherms, are signals of changes in morphology covering size scales from the atomic to the microscopic, that is Å to μm. There are obvious advantages in collecting both the wide angle (1-20Å) and small angle (20-1000Å) patterns simultaneously to unambiguously characterise such thermal events. The new apparatus comprises a Linkam hot-stage capable of controlled heating and cooling mounted in a combined SAXS/WAXS camera. The camera is equipped with a multiwire quadrant detector (SAXS) located 3.5 m from the sample position and a curved knifeedge detector (WAXS) that covers 120° of arc at a radius of 0.4 m. SAXSIWAXS is possible with a time resolution of 0.1 seconds and heating/cooling rates up to 120 °C min-1.
Speciation of Uranium After Microbial Action by XANES and XPS
Authors: Dodge Cleveland J. , Francis A. J. , Lu F. , Halada G. P. , Kagwde S. V. , Clayton C. R.
Published: March 2011

The speciation of radionuclides and toxic metals in wastes subjected to microbial action is important in determining the extent of stabilization in a disposal environment. As part of an ongoing study, we investigated the reduction of uranium by aClostridiumsp. using X-ray absorption near edge spectroscopy (XANES) at the National Synchrotron Light Source (NSLS) and X-ray photoelectron spectroscopy (XPS). XPS analysis of uranyl acetate containing hexavalent uranium exhibited a binding energy of 382.0eV at the U 4f7/2peak. The sample incubated in the presence of bacteria was shifted to lower binding energy (380.6eV), confirming the reduction of U6+to U4+at the bacterial surface. XANES analysis, using an electron yield detector, was performed at the Mv absorption edge (3d--> 5f). The absorption peak energy of the sample exhibited a shift from 3551.1eV to 3550.1eV which is higher than uranium metal (3549.6eV) but lower than U4+(3550.4eV). This indicates the presence of U3+which is probably located beneath the surface within the biomass. Anaerobic bacterial treatment of wastes containing uranyl ion can result in the stabilization of uranium.
Micro-Impact Technique and its Applications
Authors: Wu T.W. , Lee C.-K. , Wang R.H.
Published: March 2011

A micro-impact tester has been designed and built by using a piezoelectric impact hammer as an impactor driver. During the course of an impact process, force interactions between the impactor and target surfaces were monitored continuously by a miniaturized piezoelectric loadcell embedded in the flying head assembly. After having fully characterized an impact system, the trajectory of the impactor can be calculated by using the corresponding pre-recorded impact force interaction in the simulation program. The contact and returning velocities, kinetic energy loss of the impactor and the impact penetration curve are the key information obtained from the simulation. Furthermore, the impact morphology can reveal failure mechanisms of materials by providing details such as indent shapes, coating fragments, chipping, crack type and size, and other such information which are useful in assessing the fracture toughness of testing materials. The micro-impact testing was carried out in the contact velocity ranging from 0.3 to 2.0 m/sec. Three types of materials such as metal, glass and amorphous carbon were used in studying their distinct mechanical behavior under high rate indentations. The correlations between the impact conditions, energy losses, impact morphologies and material responses are illustrated and discussed.
Residual Stress Effects in the Scratch Adhesion Testing of Tantalum Thin Films
Authors: White Richard L. , Nelson John , Gerberich William W.
Published: March 2011

The effect of residual stress on the scratch adhesion critical load has been measured for sputtered tantalum films. In this single metallurgical system, six different failure modes could be observed, ranging from ductile ploughing to extensive spallation. For tantalum films deposited on silicon substrates, a 15% decrease in critical load was observed as the film residual stress increased from -1.1 GPa to +1.0 GPa. A larger percentage decrease (50%) was observed for films deposited on softer AIMg/NiP substrates. Film spallation was more extensive for films deposited over a thin carbon layer and for these films critical loads increased slightly with film stress. These results are substantially in contradiction with existing quantitative models for the scratch adhesion test and indicate that failure by shear at the film-substrate interface can be more important than failure by compressive buckling.
The Analysis of Depth-Sensing Indentation Data
Authors: Baker Shefford P.
Published: March 2011

Common methods for analyzing depth-sensing indentation data are briefly reviewed and an overview of the principal factors limiting the accuracy and precision of results obtained using these methods is presented. The largest deviations from the elastic contact models used to interpret depth-sensing indentation data arise from time-dependent displacements and uncertainties in the shape of the indenter tip, the elastic/plastic nature of the contact and the compliance of the testing machine.
Growth Stress in CVD-WGex Films Deposited by Reduction of WF6 by GeH4
Authors: Leusink G.J. , Oosterlaken T.G.M. , Janssen G.C.A.M. , Radelaar S.
Published: March 2011

Growth stresses in thin metal films on a substrate are important for integrated circuit device fabrication and reliability. The development of growth stress in blanket CVD-WGex films deposited by GeH4 reduction of WF6 is studied by in situ wafer curvature measurements. Depending on process conditions, the growth stress varies from 600 MPa tensile in β-WGex films deposited at low temperatures (T < 400 °C) to 400 MPa compressive in α-WGex films deposited at high temperatures (T > 400 °C). At very low temperatures amorphous WGex films grow without significant stress. Development of tensile growth stress is favoured by low temperatures and high growth rates, whereas development of compressive growth stress is favoured by high temperatures and low growth rates. Although the material properties of CVD-WGex films depend on process conditions, the development of growth stress in these films shows a dependence on deposition temperature and growth rate which is similar to pure α-W films deposited by H2 reduction of WF6. The results will be discussed in view of a model which has recently been put forward to explain development of growth stress in polycrystalline metal films on a substrate.
Dispersion Strengthening of AL Films by Oxygen Ion Implantation
Authors: Bader S. , Flinn P.A. , Arzt E. , Nix W.D.
Published: March 2011

Finely dispersed, stable Al-oxide particles were produced in Al films on Si substrates by oxygen ion implantation . A laser reflow technique was employed to vary the grain structure of some of the films. Transmission electron microscopy (TEM) was used to characterize the oxide particles and the grain size in the films, and a wafer curvature technique was employed to study the influence of microstructure on the deformation properties as a function of temperature.

For coarse grained laser reflowed films, ion implantation increased the strength considerably, both in compression and in tension. Weak beam TEM techniques showed that the strengthening is most likely caused by attractive interactions between dislocations and particles. As-deposited and ion implanted films showed a stable grain size of only 0.35 μm after annealing, which caused significant softening to occur in compression, especially at high temperature. However these films showed very high stresses in tension at temperatures below 130°C. In these films the presence of the oxide particles stabilizes the small grain size and this causes a weakening effect which can be attributed to diffusion controlled grain boundary relaxation mechanisms. The high tensile stresses at temperatures below 130°C can be explained by direct and indirect particle strengthening.
Dislocation Threading Through an Epitaxial Film: an Analysis Based on the Peierls-Nabarro Concept
Authors: Beltz G. E. , Freund L. B.
Published: March 2011

The Peierls-Nabarro theory of crystal dislocations is applied to estimate the critical thickness of a strained layer bonded to a substrate for a given mismatch strain. Previous analyses were based on the continuum theory of elastic dislocations, and hence depended on the artificial core cutoff parameterr0. The Peierls-Nabarro theory makes use of an interplanar shear law, which leads to a more realistic description of the stresses and displacements in the vicinity of a dislocation core, thus eliminating the need for the core cutoff parameter. The dependence of the critical layer thickness on the mismatch strain in films with a diamond cubic lattice is found to be similar to that predicted by the continuum elastic dislocation theory, provided that a core cutoff radius equal to about one-tenth the Burgers displacement is used.