bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of a Continuous Wave Incoherent Light Source (Cwils) to Semiconductor Processing
Authors: Harrison H.B. , Johnson S.T. , Cornish B. , Adams F.M. , Short K.T. , Williams J.S. 
Published: March 2011

ABSTRACTWe present results which highlight applications of a continuous wave incoherent light source in the processing of semiconductor devices. In particular, damage removal and activation of ion implanted gallium arsenide is demonstrated for both capless and capped annealing of low dose implants at temperatures of > 800°C for times < 10 s. For gallium arsenide FET applications, we demonstrate that it is possible to simultaneously carry out activation, contacting and interconnection steps by utilizing thermomigration processes which are not available with conventional furnace processing. In silicon we demonstrate that shallow multi layer bipolar structures can be successfully fabricated with anneal cycles that lead to supersaturation effects and negligible diffusion.
Beam Processing of Silicon With a Scanning CW Hg Lamp
Authors: Stultz Tim , Sturm Jim , Gibbons James 
Published: March 2011

ABSTRACTA scanning arc lamp annealing system has been built using a 3” long mercury arc lamp with an elliptical reflector. The reflector focuses the light into a high intensity narrow line source. Silicon wafers implanted with 100 Kev 75As+ to 1×l015 cm−2 have been uniformly annealed with a single scan, resulting in complete activation and negligible redistribution of the implanted species. Using a scan rate of 1cm/s, entire 3” wafers have been annealed in less than 10 seconds with this system. The system has also been used to recrystallize thin films of polysilicon deposited on thermally grown silicon dioxide. The recrystallized films contain grains that are typically 0.5–1 mm in width and several centimeters long. Surface texture measurements show the crystallites to be almost entirely (100) in the plane of the film with the orthogonal <100>direction closely paralleling the scan direction. Mosfets were fabricated in these films with surface mobilities 66% of ones fabricated in single crystal silicon. An epitaxial layer with the same crystallographic features as the recrystallized film was grown on the film itself.
Oxygen and Nitrogen Incorporation During Cw Laser Recrystallization of Polysilicon
Authors: Drowley C.I. , Kamins T.I. 
Published: March 2011

ABSTRACTThe incorporation of nitrogen and oxygen in polysilicon has been examined by SIMS. The analysis, combined with C-V measurements and ion implantation, has been used to correlate the incorporation of the two species with the fixedcharge density at the back polysilicon/Si02 interface. Laser recrystallization with a silicon-nitride encapsulation layer results in the inclusion of 2–4 × 1017 cm−3 nitrogen atoms in the polysilicon; if an oxide capping layer is used, the nitrogen level observed is at the background of the SIMS system (~1015cm−3). Either type of capping layer results in 3−4×1018cm−3 oxygen atoms being incorporated into the polysilicon. Implantation of nitrogen into the polysilicon before recrystallization increases the fixed-charge density Nf,b) at the back interface, while implanted oxygen decreases Nf, b. The high Nf, b found with a nitride capping layer is attributed to deposition of nitrogen or SiNx at the back interface.
Electrical Characteristics and Device Applications of Zone-Melting-Recrystallized Si Films on SiO2
Authors: Tsaur B-Y. , Fan John C. C. , Geis M. W. , Chapman R. L. , Brueck S. R. J. , Silversmith D. J. , Mountain R. W. 
Published: March 2011

ABSTRACTDevice-quality Si films have been prepared by using graphite strip heaters for zone melting poly-Si films deposited on SiO2-coated substrates. The electrical characteristics of these films have been studied by the fabrication and evaluation of thin-film resistors, Mosfets and MOS capacitors. High yields of functional transistor arrays and ring oscillators with promising speed performance have been obtained for CMOS test circuit chips fabricated in recrystallized Si films on 2-inch-diameter Si wafers. Dualgate Mosfets with a three-dimensional structure have been fabricated by using the zone-melting recrystallization technique.
Neutron Activation Measurements of As and Ga Loss During Transient Annealing of Gaas
Authors: Rose A. , Pollock J.T.A. , Scott M.D. , Adams F.M. , Williams J.S. , Lawson E.M. 
Published: March 2011

ABSTRACTSignificant dissociation is normally detected under non-optimised transient annealing of GaAs. We have utilised neutron activation to measure As and Ga loss from virgin and implanted material annealed under various transient conditions. Complementary RBS data are reported. In particular, surface dissociation has been measured as a function of pulsed ruby laser power and for several combinations of time and surface temperature using an incoherent light source and a vitreous carbon strip heater.The results indicate that neutron activation analysis offers a powerful tool to identify the conditions required to minimise GaAs dissociation during annealing. For examplq ruby laser pulses of energy 0.29–1.38 J cm−2 caused As loss of 4 – 90 × 10 cm−2.
Thermal Pulse Annealing of Hg1−xCdxTe
Authors: Dimiduk K. C. , Opyd W. G. , Greiner M. E. , Gibbons J. F. , Sigmon T. W. 
Published: March 2011

ABSTRACTThermal pulse annealing has been used to modify the near surface of Hg1−xCdxTe. Using anneals of approximately 260°C for seven seconds, the crystal quality of epitaxial HgCdTe surfaces can be improved as observed by MeV He+ ion channeling. Similar anneals have also been used to repair the damage resulting from a 250 keV, 101511 B/cm2 implant into HgCdTe held at LN2. For higher temperatures and/or longer anneals, surface Hg loss is observed. Rutherford Backscattering measurements are used to measure this loss. The resulting loss rate data is described by No= A exp (−ΔE/kT) where A and ΔE depend on the material composition with A = 1029, ΔE = 1.8 eV and A = 1036, ΔE = 2.6 eV for x = 0.23 and 0.4, respectively.
Ion and Electron Spectroscopy During Pulsed Laser Irradiation of Silicon
Authors: Long J.P. , Williams R.T. , Royt T.R. , Rife J.C. , Kabler M.N. 
Published: March 2011

ABSTRACTIon mass spectrometry, charged particle yields, and kinetic energy distributions of electrons and ions are used to characterize silicon wafers and vacuum-cleaved silicon surfaces under conditions related to laser annealing. We find that alkali metals dominate the positive ion emission from chemically-cleaned wafers, a mass-72 peak tentatively identified as Si2O+ comprises the main ion emission from the cleaved surface, and ion and electron temperatures can be derived from the energy distribution curves although the Si2O+ emission implies more than a simple thermal evaporation process.
Strain Relief by Tilting of Epitaxial GaAs Films on Si
Authors: Schowalter L. J. , Hall E. L. , Lewis N. , Hashimoto Shin 
Published: March 2011

AbstractIn this paper, a general formula is calculated relating the misalignment of a heteroepitaxial overlayer with respect to the substrate to the defects at the interface. High-resolution TEM studies are presented which show that the density of dislocations along the interface of GaAs grown on vicinal Si(100), with Burgers vector perpendicular to the interface, is consistent with the amount of tilt observed in ion-channeling studies. Arguments are also presented which demonstrate that the tilt observed is an effective form of strain relief but that this mechanism can only operate when the heteroepitaxial growth is nucleated by island growth. One significant conclusion is that the lower bound observed on the threading dislocation density in GaAs on Si is due to this mechanism of strain relief by tilting.
Onset of Misfit Dislocation Generation in As-Grown and Annealed Sil-XGex/Si Films
Authors: Scott M. P. , Laderman S. S. , Kamins T. I. , Rosner S. J. , Nauka K. , Noble D. B. , Hoyt J. L. , King C. A. , Gronet C. M. , Gibbons J. F. 
Published: March 2011

AbstractX-ray topography and transmission electron microscopy were used to quantify misfit-dislocation spacings in as-grown Si1-xGex films formed by Limited Reaction Processing (LRP), which is a chemical vapor deposition technique. These analysis techniques were also used to study dislocation formation during annealing of material grown by both LRP and by molecular beam epitaxy (MBE). The thickness at which misfit dislocations first appear in as-grown material was similar for both growth techniques. The thermal stability of capped and uncapped films was also investigated after rapid thermal annealing in the range of 625 to 1000°C. Significantly fewer misfit dislocations were observed in samples containing an epitaxial silicon cap. Some differences in the number of misfit dislocation generated in CVD and MBE films were observed after annealing uncapped layers at temperatures between 625 and 825°C.
Thermal Stress-Induced Grain Boundary Voiding and Notching in Narrow Al-Based Metallizations
Authors: Li Che-Yu , Black R. D. , LaFontaine W. R. 
Published: March 2011

AbstractGrain boundary voiding has been identified as a diffusional creep mechanism that produces failure of narrow Al-based metallizations during thermal aging. It is considered to be a reliability concern for sub-micron metallizations because the resulting failure rate has been observed to be strongly line width dependent. This paper presents a theoretical model for stress-induced grain boundary voiding. The proposed model is shown to account for the experimentally observed temperature and time dependence of thermal aging-induced line failure data reported in the literature.
Effect of Hydrogen on Thermal Stress in Layered Structure of Ti and Ti(Al) Thin Films.
Authors: Hu C.-K. , Ho P. S. , Gupta D. 
Published: March 2011

AbstractThe effect of hydrogen on stress in thin film structures has been investigated for Ti, Al, Ti(Al) and Al(Ti) films. The stress in the metal films was measured in-situ as a function of temperature and ambient (vacuum of 10-6Torr., forming gas and nitrogen) using a bending beam technique. The metal films were deposited on fused quartz or polyimide/fused quartz substrates using a dual e-gun evaporation method. The stress in pure Ti films was found to be strongly dependent on the annealing environment. Upon thermal cycling in a forming gas, an abrupt change of stress in the Ti film due to crack formation and delamination in the Ti film was observed. The possibility to eliminate the hydrogen effect by Al addition has been investigated. The hydrogen effect can be reduced by an addition of 5 at.% Al, but stress induced crack formation similar to the pure Ti film was still observed in this alloy film. An increase to 20 at.% Al in the alloy films eliminated the hydrogen effect, however, such an alloy film was brittle as cracks and delamination were observed after one thermal cycle from room temperature to 350 °C. A similar behavior in stress relaxation was observed in an Al-riched film with 20 at.% Ti.
Deformation in Thin Films Deposited on Rigid Substrates
Authors: Murakami Masanori 
Published: March 2011

AbstractStresses and strains are always present in thin films deposited on rigid substrates. They are introduced into the films during the deposition and/or subsequent heat and chemical treatments. Since the origins of the strains (stresses) in thin films and their shapes are different from those of bulk materials, the distribution of strains supported elastically by the films is different from that of the bulk materials. The present paper reviews deformation in thin films caused by elastic strains, using illustrative data of Pb and Nb films that were deposited on Si wafers. Also, x-ray diffraction techniques to detect such local deformation are briefly reviewed.
Thermally Induced Stresses and Strains in Laser Processing of Thin Films
Authors: Tuchman Judah A. , Welsh Lisa P. , Herman Irving P. 
Published: March 2011

AbstractThe stresses and strains induced in thermal laser processing of substrates and thin films on substrates, are obtained in terms of single integrals by solving the thermoelastic equations using a Gaussian profile laser as the heating source. This analysis is applied to silicon thin films on fused silica and sapphire substrates. In part, this study shows that defects can form in the films because the stresses induced during high temperature laser processing of silicon and similar materials can exceed the yield stress under certain experimental conditions.
Effects of Stress on the Adhesion of Metals to Polyimides
Authors: Seshan K. , Lacombe R. H. , Wagner J. B. 
Published: March 2011

AbstractThis paper describes the effects of ambient, thermal and mechanical stress on the adhesion of titanium (Ti) to polyimide (PI). Pull testing on the Ti/PI system shows that metal/polyimide bonding degrades when the composite is thermally cycled. A thermochemical mechanism is proposed that accounts for the interface degradation. We do not treat the adhesive interface as a discrete layer, but rather as a gradual “transition zone” between metal and polymer -- a zone that may grow, and/or change in composition and stress state, thus altering the adhesive properties. The mechanism predicts discontinuities that may develop in the transition zone. Through the use of finite element techniques, it is demonstrated that when loads and displacements are imposed on the composite containing interface discontinuities, large localized stresses develop. Such stresses could explain the experimentally observed low strength failures.
Characterization of Surface Mechanical Properties and Residual Stresses in Ion Implanted Nickel
Authors: Morrison D. J. , Jones J. W. , Was G. S. , Mashayekhi A. , Hoffman D. W. 
Published: March 2011

AbstractIn this study, we have measured changes in hardness and residual stress state in polycrystalline nickel samples which have undergone a variety of ion beam surface treatments including self-implantation, amorphization by ion beam mixing Ni-Al multilayers, and the formation of a two-phase microstructure by elevated temperature aluminum implantation. Hardness-depth profiles of the the near-surface regions were determined using an ultra-low load microindentation system, and residual stress states induced by the surface modifications were analyzed using optical interferometry. These property changes were correlated with the accumulation of surface fatigue damage.
Gas Phase and Surface Reactions in Mocvd of GaAs from Triethylgallium, Trimethylgallium, and Organometallic Arsenic Precursors
Authors: Omstead Thomas R. , Sickle Penny M. Van , Jensen Klavs F. 
Published: March 2011

ABSTRACTThe growth of GaAs from triethylgallium (TEG) and trimethylgallium (TMG) with tertiarybutylarsine (tBAs), triethylarsenic (TEAs), and trimethylarsenic (TMAs), has been investigated by using a reactor equipped with a recording microbalance for in situ rate measurements. Rate data show that the growth with these precursors is dominated by the formation of adduct compounds in the gas lines, by adduct related parasitic gas phase reactions in the heated zone, and by the surface reactions. A model is proposed for the competition between deposition reactions and the parasitic gas phase reactions. Model predictions are in very good agreement with experimental data for all combinations of precursors except for TEG/TMAs where extensive gallium droplet formation is observed at low temperatures. Growth of reasonable quality GaAs with Hall mobilities of 7600 cm2/Vs at 77 K using TEG and tBAs is reported for the first time.
Application of X-Ray Scattering to the in Situ Study of Organometallic Vapor Phase Epitaxy
Authors: Fuoss P. H. , Kisker D. W. , Brennan S. , Kahn J. L. 
Published: March 2011

ABSTRACTDespite their importance, the detailed surface reactions and rearrangements which occur during chemical vapor deposition remain largely undetermined because of the lack of suitable experimental probes. In principle, x-ray scattering and spectroscopy techniques are well suited to studying these near atmospheric pressure processes but advances in this area have been limited both by the lack of suitable x-ray sources and by the difficulty of integrating the growth and measurement experiments. We have developed equipment and techniques to perform in situ x-ray scattering studies of the structure of surfaces during organometallic vapor phase epitaxial (OMVPE) growth using the extremely bright undulator radiation from the PEP electron storage ring. In this paper, we describe our initial experimental results studying cleaning and subsequent reconstruction of GaAs (001) surfaces in a flowing H2 ambient. These results demonstrate the excellent surface sensitivity, low background and high signal levels necessary to study the dynamic processes associated with semiconductor growth using OMVPE.
In-Situ Diagnostics of Diamond CVD
Authors: Butler J. E. , Celii F. G. , Pehrsson P. E. , Wang H. -t. , Nelson H. H. 
Published: March 2011

ABSTRACTThe deposition of diamond, a metastable crystalline form of carbon, from low pressure gases poses intriguing questions about the mechanisms of growth. Tunable IR Diode Laser Absorption Spectroscopy, Laser Multi-Photon Ionization Spectroscopy, and Laser Induced Fluorescence were used to characterize the gaseous environment in the Chemical Vapor Deposition growth of diamond films. The quality of the deposited material was examined by optical and SEM microscopies, and Raman, Auger, and XPS spectroscopies. When a reactant mixture of 0.5% methane in hydrogen, was passed across a hot Tungsten filament (2000 C), C2H2, C2H4, H and CH3 were detected above the growing diamond surface, and concentration limits for undetected species were determined. These results are discussed in terms of simple models for species formation and consumption, as well as the implications for the diamond growth mechanism.
Chemical Reaction Pathways for the Deposition of Amorphous Silicon-Hydrogen Alloys by Remote Plasma Enhanced CVD
Authors: Parsons Gn , Tsu Dv , Lucovsky G 
Published: March 2011

ABSTRACTWe have grown thin films of a-Si:H alloys by Remote Plasma Enhanced CVD (Remote PECVD) and have studied the deposition process by mass spectrometry. We find that the concentration of silane fragments (SiHx x=0 to 3) and higher silanes (e.g. disilane Si2H6) in the gas phase is below our detection limit of =0.5%. Bias experiments and a comparison of the a-Si:H deposition rate with the known concentration of silane in the gas phase suggest that in Remote PECVD, silane molecules, SiH4*, vibrationally excited in the gas phase or on the deposition surface may lead dirtectly to a-Si:H film deposition.
Chemical Kinetics of Silicon-Rich Oxide Growth in an LPCVD Reactor
Authors: Lam C. H. , Rose K. 
Published: March 2011

ABSTRACTThe chemical kinetics of Silicon Rich Oxide (SRO) growth in a N2O-SiH4 LPCVD reactor has been studied at deposition temperatures from 610 to 680°C and pressures from 0.4 to 0.5 torr. We can produce SRO films with a wide spectrum of input reactant ratios γ = [N2O]/[SiH4] = 1 to 40. The dependence of film composition on γ changes dramatically in a region around γ = 2.Growth for γ < 2 is consistent with the chemical kinetics of SIPOS growth. Growth for γ > 20 can be explained by oxidation of silicon in the bulk of the growing SRO film. We can explain growth from γ ≈ 4 to 20 by considering the chemical kinetics of possible binary surface reactions which may produce Si-Si or Si-O bonds. This allows us to accurately model the dependence of SRO growth rate in this region as a function of γ, pressure, and deposition temperature.
The Decomposition of Trimethylgallium and Trimethylaluminum on Si(100)
Authors: Lee F. , Gow T. R. , Lin R. , Backman A. L. , Lubben D. , Masel R. I. 
Published: March 2011

ABSTRACTThe decomposition of trimethylgallium (TMG) and trimethylaluminum (TMA) on Si(100) is studied by TPD, XPS, and EELS. It is found that the decomposition of TMG is largely an intramolecular process. First one of the methyl groups in the TMG reacts with a hydrogen in another methyl group liberating methane. This leaves a CH2 group bound to the gallium which is seen clearly in EELS. Subsequently, another hydrogen reacts with a methyl group producing additional methane. This leaves a gallium atom and a CH group on the surface. Hydrogen desorbs, while carbon is incorporated into the growing film. Careful calibration of the peak areas in the TPD data indicates that 2.1 ± 0.3 moles of methane, 0.5 ± 0.03 moles of hydrogen, 1 mole of gallium, and 0.95 ± 0.1 moles of surface carbon are produced for every mole of TMG which decomposes. Since, the decomposition ratio is independent of the state of the surface, the surface orientation, and the level of impurities on the surface, it appears that the surface is not a direct participant in the reaction.TMA adsorbs as dimers. However, the dimers decompose upon heating to 400 K. Thereafter, the chemistry of TMA decomposition is similar to that for TMG. Nonetheless, the product ratio varies with the TMA coverage, the state of the surface, and the aluminum coverage. Also, silicon-carbon bonds are evident at 600 K in EELS. It is suggested, therefore, that the decomposition of TMA is similar to that of TMG, except that methyl groups in TMA have a tendency to migrate to the support. In both TMA and TMG, carbon incorporation is an intrinsic part of the decomposition process. This suggests that TMA and TMG would not be appropriate source gases when one needs to produce films with very low carbon levels.
Valence Hole Localization in Molecular Auger Decay
Authors: Lapiano-Smith D. A. , Ma C. I. , Wu K. T. , Hanson D. M. 
Published: March 2011

ABSTRACTStudies of the unimolecular decay, following the excitation of core electrons of the carbon and fluorine atoms in carbon tetrafluoride and silicon and fluorine in silicon tetrafluoride by monochromatic, synchrotron radiation, provided evidence for a “valence bond depopulation” fragmentation mechanism. The fragmentation processes were examined using time-of flight mass spectroscopy. The mass spectra show the distribution of ions collected in coincidence with low and high energy electrons. Distinct changes in the mass spectra with atomic site of excitation and photon energy are observed. The observation of F2+ ions in the time-of-flight mass spectra following excitation of a fluorine is electron in SiF4 is significant because it provides direct evidence for the formation of a localized, two-hole, final valence state that persists on the time scale of fragmentation. In contrast, the lack of F2+ ions from CF4, indicates that the fragmentation occurs through a delocalized two-hole state.
Mechanisms in the Ion-Assisted Etching of TiSi2
Authors: O'Brien W. L. , Rhodin T. N. , Rathbun L. C. 
Published: March 2011

ABSTRACTA detailed investigation into the mechanisms of the ion-assisted etching of TiSi2 using 1000 eV argon ions and chlorine gas is reported. X-ray photoelectron spectroscopy (XPS) was used to investigate surface product distributions and modulated ion beam mass spectroscopy (MIBMS) was used to investigate gas phase product distributions. Identical experiments were performed on silicon and titanium single crystal substrates. Information on chemical mechanisms during ion-assisted etching was obtained by comparing the product distributions of the three substrates. For each substrate, the di and tetrachlorides were the major gas phase products. These products were emitted with high thermal velocities following a surface residence process. TiCl and TiCl2 products were found on the titanium surface after simultaneous exposure to chlorine and argon ions, but not on the TiSi2 surface. These observations are discussed in terms of specific chemical mechanisms which are critical during ion-assisted etching.