bluuebunny/crossref_metadata_2025 huggingface dataset:
Modifying Crystallographic Orientations of Polycrystalline Si Films Using Ion Channeling
Authors: Kung K. T-Y. , Ivepson R. B. , Reif R.
Published: March 2011

Polycrystalline silicon films 4800 Å thick deposited via low pressure chemical vapor deposition on oxidized silicon wafers have been amorphized by silicon ion implantation and subsequently recrystallized at 700°C. Due to channeling of the ions through grains whose <110> axes were sufficiently parallel to the beam, these grains survived the implantation step and acted as seed crystals for the solid-phase epitaxial regrowth of the film. This work suggests the feasibility of combining ion implantation and furnace annealing to generate large-grain, uniformly oriented polycrystal1ine films on amorphous substrates. It is a potential low-temperature silicon-on-insulator technology.
Photoelectron Spectroscopy of Conduction-Electron Energy
Distributions in Laser-Excited Silicon
Authors: Long J.P. , Williams R.T. , Rife J.C. , Kabler M.N.
Published: March 2011

Electron energy distributions, extending from equilibrium surface states
through transiently populated conduction band states, have been observed in
laser excited silicon by means of transient photoelectron spectroscopy.
Atomically clean (111) wafers in UHV were excited by 90 nsec, 2.33 eV or 65
nsec, 4.66 eV pulses. Photoelectron spectra were obtained with the 4.66 eV
pulses. Photovoltage shifts have been measured and found to saturate. We
have identified a feature in the excited state portion of the spectra due to
electrons which have equilibrated in the conduction band minima (CBM).
Electron temperatures as a function of 2.33 eV pump fluence have been
extracted from the spectra and are shown to be in equilibrium with the
lattice above 1100 K. Very hot non-equilibrium electrons are also observed
to ~ 4 eV above the CBM. A method of determining the diffusion depth of CBM
electrons has been developed and applied to our data.
Diffusion Mechanisms and Nonequilibrium Defects in SI
Authors: Mathiot D. , Pfister J. C.
Published: March 2011

The problem of the respective contributions of vacancies and self interstitials to diffusion mechanims in silicon is clarified by using a consistent model for the diffuion of P, As and B which involves the resolution of the coupled continuity equations for the impurities, the vacancies and the self-interstitials. This model allows also the understanding of basic features concerning the kinetics of the point defects in presence of impurities.
Transient Enhanced Diffusion and Gettering of Dopants in Ion Implanted Silicon
Authors: Pennycook S. J. , Narayan J. , Culbertson R. J.
Published: March 2011

We have studied in detail the transient enhanced diffusion observed during furnace or rapid-thermal-annealing of ion-implanted Si. We show that the effect originates in the trapping of Si atoms by dopant atoms during implantation, which are retained during solid-phase-epitaxial (SPE) growth but released by subsequent annealing to cause a transient dopant precipitation or profile broadening. The interstitials condense to form a band of dislocation loops located at the peak of the dopant profile, which may be distinct from the band formed at the original amorphous/crystalline interface. The band can develop into a network and effectively getter the dopant. We discuss the conditions under which the various effects may or may not be observed, and discuss preliminary observations on As+ implanted Si.
Defect Formation and Hydrogen Trapping in H+ Implanted FZ Silicon
Authors: Choyke W. J. , Spitznagel J. A. , Doyle N. J. , Wood S. , Irwin R. B.
Published: March 2011

The formation and annealing of buried damage layers in hydrogen implanted N-type float zone <111> silicon has been studied by Rutherford Backscattering/ion channeling and cross-section transmission electron microscopy. Implantation with 50 keV or 75 keV H+ ions was conducted at temperatures of 95K, 300K and 800K at fluences of 2×1017 H+/cm2, 8×1017 H+/cm2 and 1×1018 H+/cm2. Post implantation annealing was conducted at temperatures up to 800K. The results show a temperature dependent transition from a highly hydrogen doped amorphous zone bounded by strongly diffracting (TEM) 2–5 nm diameter defects for implantation at 95K to a crystalline microstructure containing small dislocation loops and ∼40% of the implanted hydrogen for implantation at 300K. Defect production and annealing and hydrogen trapping in the damage zone are shown to depend on the relative implantation and post implantation annealing temperatures.
The Chemistry of Oxygen in Silicon
Authors: Mikkelsen J. C.
Published: March 2011

Some of the key issues involving the chemistry of oxygen in silicon crystals are presented in this paper. The incorporation of oxygen into Czochralski-grown ingots from melt contact with silica crucibles is described in the context of the Si-SiO2 phase diagram. The techniques for characterizing oxygen in silicon are reviewed, with an emphasis on the use of secondary ion mass spectrometry (SIMS) and 18O isotope substitution. The intrinsic diffusivity and solubility of oxygen in silicon derived from these SIMS measurements are compared to similar results from other techniques as well as related extrinsic behavior of oxygen. Aggregation phenomena involving oxygen, including thermal donor formation and precipitation are discussed. Finally, the recent progress in understanding internal gettering and shear stress are summarized.
A Model That Describes the Role of Oxygen, Carbon, and Silicon Interstitials in Silicon Wafers During Device Processing
Authors: Hartzell R. A. , Schaake H. F. , Massey R. G.
Published: March 2011

A model has been developed that simulates oxygen precipitation in silicon wafers during high temperature device processing. The approach used to calculate the nucleation and growth of oxygen precipitates is radically different from other approaches presented in the literature. A discrete rate equation representation of nucleation and growth has been transformed into a continuum representation in the form of a partial differential equation. This partial differential equation describing both the statistical clustering of oxygen during nucleation and the diffusion driven transport during precipitate growth is solved continuously starting from crystal growth through any arbitrary time-dependent temperature process.
Oxygen Precipitation in CMOS Wafers
Authors: Forbes L. , Whitwer F. D. , Peng J. D.
Published: March 2011

The application of denuding, nucleation, and intrinsic gettering in CMOS integrated circuit processes is described. Specifically, it will be demonstrated that an initial oxidizing step, as many manufacturers are using, seriously retards the effectiveness of any subsequent nucleation step or procedure. The results of a large number of one-step, two-step, and three-step heat treatments are summarized and design criteria for controlled oxygen precipitation in integrated circuit fabrication are described. Two-step heat treatments, without denuding and with the nucleation step first, have been used to induce precipitates close to the surface of CMOS wafers and DLTS measurements made to deduce the effectiveness of intrinsic gettering and the electrical characteristics of precipitation induced microdefects.
Rapid Diffusion of Molybdenum Trace Contamination in Silicon
Authors: Tobin S. P. , Greenwald A. C. , Wolfson R. G. , Meier D. L. , Drevinsky P. J.
Published: March 2011

Molybdenum contamination has been detected in silicon epitaxial layers and substrate wafers after processing in any one of several epitaxial silicon reactors. Greatly reduced minority carrier diffusion lengths and lifetimes are consistent with Mo concentrations measured by DLTS in the 1012 and 1013 cm−3 ranges. Depth profiling of diffusion length and the Mo deep level show much greater penetration than expected from previous reports of Mo as a slow diffuser. The data indicate a lower limit of 10−8 cm2/sec for the diffusion coefficient of Mo in silicon at 1200°C, consistent with high diffusivities measured for other transition metals.
Diffusion of Dopants in (111) Silicon During High Temperature Heat Treatment in Nitrogen
Authors: Kook T. , Jaccodine R. J.
Published: March 2011

The diffusion of various dopants( B, P, As, and Sb) in (111) silicon during high temperature( 1100°C ) heat treatment in nitrogen depends on the capping layers, i.e., SiO2, Si3 N4, and SiO2 + Si3 N4, layers. The junction motion of all dopants were retar ed in the bare silicon compared with that in the SiO2 + Si3 N4 capped silicon. The apparently retarded junction motion of As and sb diffused specimens in the bare silicon is due to the severe out-diffusion loss of dopant atoms and As and Sb diffusion are in fact enhanced during thermal nitridation of silicon in N2.
Ion Implantation Disorder in Strained-Layer Superlattices
Authors: Arnold G. W. , Picraux S. T. , Peercy P. S. , Myers D. R. , Biefeld R. M. , Dawson L. R.
Published: March 2011

Cantilever-beam bending and RBS channeling measurements have been used to examine implantation-induced disorder and stress buildup in In0.2Ga0.8As/GaAs SLS structures. Implantation fluences from 1011 to 1015/cm2 were used for 150 keV Si, 320 keV Kr, and 250 keV Zn in SLS and GaAs bulk materials. The critical fluence for saturation of compressive stress occurs prior to amorphous layer formation and is followed by stress relief. For all the ions the maximum ion induced stress scales with energy density into atomic processes and stress relief occurs above ∼1 × 1020: keV/cm3. Stress relief is more pronounced for the SLSs than for bulk GaAs. We suggest that stress-relief may lead to slip or other forms of inelastic material flow in SLSs, which would be undesirable for active regions in device applications. Such material flow may be avoided by limiting maximum fluences or by multiplestep implantation and annealing cycles (or hot implants) at high fluences.
Compound Semiconductor Surfaces and Interfaces: Whence Fermi Level Pinning?
Authors: Woodall Jerry M.
Published: March 2011

Except for a few special cases, the electrical and optical properties of most III-V semiconductor surfaces and interfaces can be explained in terms of surface Fermi level pinning. However, despite years of research there is no universal agreement on the origin of this pinning. This problem is of more than just academic interest since pinning affects optoelectronic device performance via surface recombination losses, and high speed device performance through uncontrollable ohmic and Schottky contact properties for MESFETs and through a high interface trap density for MISFETs.

This talk reviews some of the approaches to the pinning problem and presents some recent results on the role of misfit dislocations in pinning. In particular it will be shown that there are are several models which can explain the usually observed pinning positions. However, we have developed a modified work function model capable of explaining both the usual pinning positions and the experimentally observed exceptions in Schottky barrier height for some metal/semiconductor interfaces. The electrical properties of lattice mismatched GaInAs/GaAs heterojunctions suggest that Fermi level pinning occurs at misfit dislocations.
Electron - Beam Measurements of Epitaxial GaAs Layers
Authors: Paz O. , Borrego J. M.
Published: March 2011

In studying the growth of epitaxial layers in III-V compounds, it is advantageous to obtain information on the early stage of the growth that takes place at the substrate-epitaxial layer interface. In this paper, we describe a method of measuring the recombination velocity at this interface, as well as the minority carrier diffusion length in the bulk of the epitaxial layer. A bi-directional diffusion of excess carriers was modeled, with layer thickness, diffusion length and recombination velocity as variables. Layer thickness was determined using spreading resistance, the other two variables can be separated by measuring layers of several thicknesses. Some carriers diffuse from the point of generation toward the surface and are collected at a Schottky barrier depletion layer, The remaining carriers diffuse from the point of generation toward the epi-substrate interface where they recombine.
A Comparison of Transient Annealing Methods for Silicide Formation
Authors: Harper R. E. , Sofield C. J. , Wilson I. H. , Stephens K. G.
Published: March 2011

Nickel and cobalt silicides have been formed by raster-scanned electron beam and flash-lamp irradiation of thin metal films on single crystal (100) and (111) silicon wafers. RBS and channelling measurements indicate that the NiSi2 is epitaxial and of good crystalline quality (Xmin 4% on (111)); epitaxial CoSi2 was more difficult to form and of somewhat poorer quality. The elastic recoil technique has been used to determine bulk and interfacial light element contamination. These measurements have been correlated with resistivity and SEM studies of the surface textures.
Cross-Sectional Tem Study of Rhodium on Single Crystal and Amorphous Silicon
Authors: Herd S. R. , Psaras P. A. , Fishera I. J. , Tu K. N.
Published: March 2011

A crystalline interfacial bilayer, consisting of about 5nm each of RhSi and Rh2Si was found after E-beam deposition of 95nm of Rh onto either Si[100] or α-Si substrates. Cross sectional TEM of the as-deposited and annealed specimens showed no change occurred after 24hrs at 200° C. With infinite supply of Si, as on the Si[100] substrate, RhSi was found as a major growing phase, although Rh2Si also grew at a much slower rate. With a limited supply of Si, as in the α-Si case, RhSi first formed until all α-Si was consumed (2 hrs at 400°C) and then transformed partially to Rh2Si after 4 hrs at 400°C. This transformation could be confirmed by RBS since Rh2Si layer thickness exceeded 30nm
Structural Unit Models for High Angle Symmetrical Tilt Boundaries in Ordered Compounds with the Ll2 Structure
Authors: Farkas D.
Published: March 2011

Hard sphere models were used to determine densest configurations in symmetrical [100] and [110] tilt boundaries in compounds with the Ll2 structure. The minimum allowed interatomic distances used in these models were estimated from interatomic potentials and the structures of the intermetallic phases in the binary system. The structural unit model is used to analyze the possible ground states for ordering.

Two different cases were analyzed corresponding to compounds with “soft” potentials (i.e. Cu3 Au) and “hard” potentials (i.e. Ni3Al). For the Cu3Au type the grain boundary structures obtained were similar to those reported by other investigators for pure fcc metals. Several boundaries were found to be a “two phase” structure, differing in composition and ordering state. This leads to a certain degree of clustering in the boundaries. The contribution of clustering to the grain boundary energy is calculated in a point approximation based on the first coordination shell.

For compounds of the Ni3Al type the structures that are densest were found to be generally diffetent from the low energy configurations of boundaries in, pure fcc metals and Cu3 Au. These configurations preserve order, but are much less dense. The possibility of grain boundary “phases” that are not present in other fcc materials may constitute an explanation for the extreme GB weakness observed in Ni3Al and other Ll2 compounds with high ordering energy.
Dislocation Core Structure and the Anomalous Yield Behavior of Li2Ordered Alloys At Elevated Temperatures
Authors: Vitek V. , Pope D. P.
Published: March 2011

In many LI2ordered alloys the flow stress increases with increasing temperature and is in this “anomalous” regime strongly dependent on orientation and sense of the applied stress. These dependences can be predicted from the nature of the dissociation and core structure of the 1/2<101> screw superpartials in these alloys. Computer modelling shows that two different configurations, a glissile one on {lll} planes and a sessile one on {010} planes, exist and both are described here in detail. The anomalous increase of the flow stress may then be explained by an increasing amount of core transformations from the glissile to sessile forms as the temperature increases. The theoretical model for the immobilization of screw dislocations by this mechanism is then discussed and its validity illustrated by comparison with experimental results on Ni3(Al, Ta) single crystals.
High Temperature Ductility Minimum in Rapidly Solidified Ni3Al - B
Authors: Taub A. I. , Huang S. C. , Chang K. M.
Published: March 2011

The elevated temperature mechanical properties of rapidly solidified, boron doped Ni3Al have been investigated. Melt spun ribbon, plasma deposits and HIP'ped powder were tested with the same general results. It was found that the boron doped, rapidly solidified alloy exhibits an increasing flow stress with increasing temperature similar to that reported for conventionally cast Ni3Al. In addition, the rapidly solidified alloys exhibited a severe ductility minimum in the range 500–750C. The ductility minimum is relatively insensitive to both boron and aluminum concentration, but the embrittlement onset temperature changes with processing and testing parameters. In all cases, the onset of the ductility drop coincides with the onset of the decrease of the flow stress. It is postulated that this behavior is due to a change in the flow mechanism at elevated temperature to one that is associated with grain boundary stress concentration.
Cyclic Deformation Behavior of Ni3Ge Single Crystals At Room Temperature
Authors: Pak Han-Ryong , Hsiung Leih-Ming , Kato Masaharu
Published: March 2011

Fully reversed strain-controlled, tension-compression tests were performed at room temperature to study cyclic-deformation properties of Ni3Ge single crystals. The cyclic deformation is performed with the stress axis parallel to the [1 1.94 2.69] direction at a strain rate of 1.0 × 10-4 s-1 and at a total-strain amplitude between 5.0 × 10-4 and 1.5 × 10-3. Cyclic strain-hardening occurs to saturation over the range of the employed strain amplitudes. The cyclic-stress amplitude is higher in compression than in tension at a plastic-strain amplitude larger than 1 × 10-5 where screw dislocations are operative. This stress asymmetry becomes more prominent (i.e., the mean stress-amplitude becomes larger in magnitude) as the plastic-strain amplitude becomes larger. At a plastic-strain amplitude less than 1 × 10-5 where edge dislocations are operative, the stress amplitude is symmetric. A similar stress asymmetry is also observed for monotonic flow stress. The cyclic hardening is explained by considering an interaction between the screw dislocations.
Effects of Do3 Transitions on the Yield Behavior of Fe-Al Alloys
Authors: Inouye H.
Published: March 2011

The effect of DO3 transitions on the yield behavior of alloys near the Fe3 Al composition was investigated by tensile tests. Above 400°C, DO3 (Fe3 Al) ordered alloys exhibited an anomalous increase in yield strength with temperature with a peak value around 560 to 600°C which was not observed if the DO3 ordered alloys were also aged before testing. This yield behavior is explained by the precipitation of a (disordered solid solution) and the formation of B2 (FeAl) via the sequential reactions: DO3→α+DO3→α+B2.
Creep in Ordered Nickel Base Alloys
Authors: Strutt P. R. , Kear B. H.
Published: March 2011

This paper examines the fundamentals of deformation behavior in ordered y′ (Ni3Al), β (NiAl) and β′ (Ni2AITi) phases, and specific two phase y/y′ and B/B′ alloys. The relative creep strengths of these ordered nickel-base alloys are discussed. Differences in creep behavior are explained in terms of the effects of temperature, crystallographic orientation and alloying on creep deformation mode. In particular, it is shown that trace additions of boron and carbon to y/y′ alloys, or deviations from stoichiometry in β′ -type alloys can exert a strong influence on creep behavior.
The Production and Thermal Stability of a Refined Dispersion of Er2O3 in Ti3Al using Rapid Solidification Processing
Authors: Konitzer D. G. , Fraser H. L.
Published: March 2011

The use of rapid solidification processing to produce a refined dispersion of second phase in Ti3Al is demonstrated. Laser surface melting produces a disordered solid solution of Ti and Al with a supersaturation of Er and 0. A refined dispersion of Er2O3 is formed on heat treatment at 973 K. This oxide is found to be stable at elevated temperatures up to 1173 K.
Volume and Grain Boundary Diffusion in Ll2Alloys with Special Reference to Ni3Al Compounds
Authors: Chou T. C. , Chou Y. T.
Published: March 2011

Experiment and theory of diffusion in Ll(2) alloys are briefly reviewed. Current work on volume and grain boundary diffusion in Ni(3)Al alloys are presented and discussed.
Physical Properties of Ni3Al Containing 24 and 25 Atomic Percent Aluminum
Authors: Williams R. K. , Graves R. S. , Weaver F. J. , McElroy D. L.
Published: March 2011

Thermal conductivity, electrical resistivity, Seebeck coefficient and thermal expansion data were obtained on well-annealed Ni3Al containing 24 and 25 at. % Al. The results span the temperature range 300 to 1000 K. The expansion coefficients did not vary with composition and increased with temperature, reaching values of aIout 17 × 10−6 K−1 at 1000 K. The thermal conductivity and electrical resistivity changed rapidly with composition, and the thermal conductivity of 24 at. % Al is as much as 30% lower than that for stoichiometric Ni3A1. The electronic Lorenz function of Ni3Al was obtained by subtracting the estimated phonon conductivity component and found to be within about 5% of the Sommerfeld prediction from 300 to 1000 K. The electrical resistivity results for stoichiometric Ni 3Al are influenced by the loss of ferromagnetic order at lower temperatures and are not adequately described by the Bloch-Grüneisen equation.
Pseudoelasticity and Pseudotwinning in Ordered Shape-Memory Alloys
Authors: Zangwill A. , Bruinsma R.
Published: March 2011

Shape-memory behavior is a complicated phenomenon which Intimately relates macroscopic strain recovery with martensitic phase transformation. A vital step In the theoretical understanding of this effect is a clear picture of a superficially rather simpler phenomenon: martensitic pseudoelasticity. Within the martensftic phase, a number of ordered alloys exhibit deformation strain recovery which Is reminiscent of rubber elasticity. The deformation Is observed to occur via coherent motion of parallel twin boundaries. In this case, where long range elastic accomodatlon forces play no role, the origin of the restoring force on the twin boundaries is still unclear. In this work, we present a quantitative theory which generalizes previous suggestions in the literature and unifies this phenomenon with elastic mechanical untwinning. Our description is based on the concept of a “pseudotwin” originally proposed by Laves and later elucidated by Cahn. Here, the motion of a twin boundary generates a new metastable crystallographic structure (the pseudo-twin) of locally higher free energy. This notion not only provides a source for a “volume” restoring force but leads to a natural descriptioni of observed stabilization effects. Specific experiments to test our description will be proposed.
Kinetics of the SRO-LRO Transformation in NI4MO
Authors: Stansbury E. E.
Published: March 2011

The isothermal time-temperature dependence of the transformation from SRO to LRO as measured by resistivity changes is given. Problems of defining an initial state from which the transformation occurs are reviewed with emphasis on the microdomain structure from which the LRO structure develops. Questions of homogeneous transformation relative to heterogeneous transformation by clear nucleation and growth are addressed in terms of experimental evidence and theoretical predictions. Strong evidence for a nucleation and growth mechanism, at least above 750° C, is presented.
Nonequilibrium Crystal Growth During Pulsed Laser Annealing
Authors: White C. W.
Published: March 2011

Solidification of the melted region during pulsed laser annealing occurs under conditions that are far from equilibrium at the interface. Studies of laser annealing of ion implanted silicon can be used to provide a wealth of information on nonequilibrium crystal growth phenomena.
Study of the Crystalline to Amorphous Silicon Boundary Following Laser Induced Solid Phase Epitaxy.
Authors: Gonchond J. P. , Rozgonyi G. A. , Bois D.
Published: March 2011

EBIC and voltage contrast SEM microscopy, combined with optical microscopy. chemical etching and Talystep profiling have been used to investigate cw laser annealing of a-Si in the slip-free SPE regime. Special attention is devoted to the edges and extremities of the line scans, i.e. to the c-to a-Si boundary. At very low power, evidence is given for an initial reordering and thus electrical activation stage of the a-Si. For the higher power range regrowth occurs through two different processes. The EBIC yield is interpreted in terms of a balance between annealing of the ion implantation damage and defect generation in the si substrate during the laser annealing. These results are extended to the case of a scanned electron beam annealing.
Evidence Against a Reduced Melting Temperature in Amorphous Silicon
Authors: Kokorowski S.A. , Olson G.L. , Roth J.A. , Hess L.D.
Published: March 2011

Experimental results are presented which indicate that amorphous silicon does not melt at a temperature significantly lower than the melting point of crystalline silicon (1693°K), contrary to recent reports which suggest a 300 to 500°K melting point depression. Time-resolved optical reflectivity measurements are used to determine the temperature and to investigate phase changes which occur in silicon during cw laser heating. It is shown that amorphous silicon films produced by arsenic implantation into Si(100) do not melt when heated to temperatures in excess of 1600°K. An alternate interpretation of previous work that is consistent with the present findings is proposed.
Laser Processing in Silicon Molecular Beam Epitaxy
Authors: De Jong T. , Smit L. , Korablev V.V. , Saris F.W.
Published: March 2011

We have grown epitaxial silicon films on silicon (100), (110) and (111) oriented substrates, using pulsed ruby laser irradiation as a means to obtain clean, ordered substrate surfaces. On these surfaces epitaxial layers were grown in two ways: I. Rȯom temperature deposition and pulsed laser induced epitaxy of 100–300 nm films was carried out repeatedly, yielding ∼1 μm thick epitaxial layers. II. Low temperature molecular beam epitaxy (M.B.E.), even at 250°C on Si(100),of layers up to 1 μm.

Applying the second technique to implanted substrates, we annealed and cleaned arsenic implanted silicon (100) samples in situ, and produced epitaxial overlayers of 100–1000 nm, thus creating a buried n-type channel in silicon.
Oxygen-Trapping and Oxidation Induced by Laser Irradiation in Silicon
Authors: Liu Yung S. , Chiang Shin-Wu , Katz W.
Published: March 2011

Rapid oxidation in silicon induced by nanosecond UV laser pulses has been recently reported [1]. A significant amount of oxygen was observed to be incorporated in theregrown silicon layer when irradiation took place in air or in oxygen ambient. The fundamental interaction and transport kinetics involved include: incorporation of impurity during surface melting, trapping of solute during resolidification, and rapid reaction to form chemical bonds. The present study has investigated the mechanism of oxygen incorporation and trapping under various regrowth conditions. Oxygen depth-concentration distributions were analyzed using secondary-ion-mass spectroscopy (SIMS). The oxide formed was studied using differential Fourier-Transformed IR (FT-IR) spectroscopy.
Surface Electronic Properties of Ionimplanted Laser-Annealed Si(111)
Authors: Eastman D.E. , Heimann P. , Himpsel F.J. , Reihl B. , Zehner D.M. , White C.W.
Published: March 2011

Highly-degenerate As-doped n-type and B-doped p-type Si(l11)−(1×1) surfaces have been prepared via ion implantation and laser annealing and studied using photoemission. For As concentrations of ∼4–7%, surface states become very different from those for intrinsic Si(l11)−(1×1) and the Fermi level EF at the surface moves to the conduction band minima resulting in a zero height n-type Schottky barrier. Emission from the conduction band minima has been directly viewed in momentum space.
Laser Induced Diffusion of Radioactive As into Si
Authors: Pfeiffer Loren , Kovacs T. , Celler G. K. , Trimble L. E. , Jacobson D. C.
Published: March 2011

A high efficiency technique for incorporating As or other high volatility elements into Si and other semiconductors by laser pulse processing is described. By this method more than 80% of the As atoms painted onto a Si surface were made to relocate onto substitutional sites in the 73Si crystal. Mossbauer analysis of laser diffused As atoms in a Ge crystal indicates that although the final As sites are >97% substitutional, the majority are associated with one or more defects not seen in conventionally diffused material.
Pulse Electron Beam Annealing of Phosphorus-Implanted Silicon
Authors: Borisenko Victor , Labunov Vladimir
Published: March 2011

Low-energy electron beam pulses of 0.2–0.8 s duration have been used to anneal silicon wafers implanted with 1.4×1015 P+/cm2 at 30 and 100 keV. Sheet resistivity, carrier concentration profiles and phosphorus atom distributions have been measured. It has been found that the impurity is completely activated without a noticeable diffusion at the energy density of 30 J/cm2 and higher. The annealing process appears to take place via a solid phase diffusion and annihilation of radiation defects.
CW Laser Induced Deep Level Defects in Virgin Silicon.
Authors: Chantre A. , Kechouane M. , Bois D.
Published: March 2011

Deep Level Transient Spectroscopy has been used to investigate cw laser induced defects in virgin silicon. Two main regimes have been found. In the solid phase regime, two well defined deep levels at Ec−0.19 eV and Ec−0.45 eV are observed. This point defect introduction is proposed to be involved in the degradation of ion-implanted cw laser annealed junctions. The mechanism leading to point defects generation is likely to involve trapping of in–diffused vacancies, quenched–in from the high temperature state. In the slip lines or melt regimes, additionnal deep levels are detected, which are ascribed to dislocations.
Defect Analysis of Silicon Irradiated by Pulsed Ion Beams
Authors: Mader Siegfried , Chu Wei-Kan
Published: March 2011

Silicon wafers with (001), (011), and (111) orientations were irradiated with pulsed Ba beams that caused shallow surface melting. Upon resolidification the dislocations are trapped with configurations which are characteristically different for each orientation. A novel feature are dislocations with a [100] Burgers vectors. The dislocations accommodate part of the thermal misfit between substrate and solidifying layer.
Interplay of Soret vs. Normal Impurity Diffusion During Laser or E-Beam Induced Heat Flow Transients in Metals
Authors: Dona' Dalle Rose L.F. , Miotello A.
Published: March 2011

In the growing amount of the experimental data on the diffu sion processes of implanted impurities in a metal sample irradiated by highly energetic and very short pulses, some order may be introduced by the knowledge of the structure of induced thermal transient. The differences in such a structure due to two different energy sources (laser and electron beam) are de scribed with reference to the conditions under which Soret diffusion may be experimentally observed as distinct from nor mal diffusion. Laser induced transient seem to offer this possibility.

Some previously reported diffusion processes in laser irra diated systems are reinterpreted on this basis, showing the importance of the Soret effect.
Raman and Optical Properties of the Pulsed Laser Annealing Phase of SI
Authors: Compaan A. , Aydinli A. , Lee M. C. , LO H. W.
Published: March 2011

Raman measurements of temperature reported earlier have been repeated using a doubled Nd: YAG pulse for excitation and an electronically delayed dye laser pulse. These results, together with a variety of experimental tests of the Raman method, confirm the validity of the small temperature rise during pulsed laser annealing. Transmission measurements spanning the visible and near IR show that there exists a thin (∼ 70 nm) layer at the surface in which the induced absorption coefficient is ∼ 7 × 105 cm−1.
Seeded Growth of Si Over SiO2 Substrates by CW Laser Irradiation
Authors: Trimble L. E. , Celler G. K. , Ng K. K. , Baumgart H. , Leamy H. J.
Published: March 2011

Seeded epitaxial growth of Si over SiO2 is demonstrated in two types of structures. In the first case, rectangular pads of deposited Si were recessed into a thick SiO2 film. Narrow (≃ 5μm) via holes in SiO2 linked the pads with the bulk Si substrates. In the second embodiment, SiO2 patterns were recessed into the Si wafers which were then covered with a continuous 0.5μm poly-Si layer. In both cases, nearly planar geometries were maintained by use of local oxidation and etching techniques. Silicon was recrystallized with a focused Ar+ laser beam. Depending on the scanning conditions and the Si pattern geometry, single crystal growth propagated between 30 and >500μm. The factors influencing the extent and quality of the crystallized regions are discussed.
Line-Source E-Beam Crystallization of SI on Silicon Nitride Layers
Authors: Knapp J. A. , Picraux S. T. , Lee K. , Gibbons J. F. , Sedgwick T. O , Depp S. W.
Published: March 2011

We report the use of a swept line–source electron beam for liquid phase recrystallization of Si films on Si3N4 layers over Si substrates. For the case of 5000Å of Si on 1000Å of Si3N4 layers over Si Si3N4, we have demonstrated the growth of Si crystalline regions as large as 0.5 × 5 mm of predominately [100] orientation normal to the film and [010] in the sweep direction. The nucleation of grain growth for this case occurred at small defects in the nitride layer at the edge of the treated area, growing out as far as 500 μm over intact nitride. Thicker nitrides (2500Å) remained intact at power densities useful for treating the Si film. For this thicker nitride we demonstrate non–seeded growth for single and repetitively melted Si. In all cases the surface morphology of the regrown regions is suggestive of rapid growth along <100> directions.
Characterization of Thermal Oxides of Laser Annealed Polysilicon
Authors: Shah Rajiv R. , Mays Robert , Lloyd Crosthwait D.
Published: March 2011

We report an investigation of the effects of laser processing on the thermal oxides of polysilicon. LPCVD polysilicon, 500 nm thick, deposited on 500 nm thermal oxide of single crystal silicon was laser processed at various stages in the process sequence for device fabrication. Effects of CW Ar+ and pulsed 1.06 and 0.53 μm laser processing were investigated. Laser annealed polysilicon was oxidized in a steam ambient. Using a second level of polysilicon, guard ring diode and capacitors were fabricated. Electrical characterization revealed an improvement in breakdown field strengths of these oxides without deleterious effects on any of the associated interfaces.
Laser Processing of Porous Silicon
Authors: Baumgart H. , Frye R. C. , Trimble L. E. , Leamy H. J. , Celler G. K.
Published: March 2011

Silicon can be prepared in a unique morphological form by anodic dissolution in HF. The resultant material contains pores of 10–100Å diameter in numbers sufficient toproduce a high surface area, low density single crystal. We have investigated the potential of both pulsed and CW laser processing in this material for dielectric isolation applications. Pulsed processing at λ = 532 nm yields fused surface layer structures that are epitaxial. The porous Si that underlies this surface film is undisturbed and can beoxidized to produce vertical isolation from the substrate.
Schottky-Diodes in Laser Recrystallized Polysilicon
Authors: Schaber H. , Schelpmeier H. , Werner W.M. , Cutter D.
Published: March 2011

Schottky-diodes on laser recrystallized polycrystalline silicon are studied and compared to diodes fabricated on conventional, fine grained poly-Si. A strong dependence of reverse current on grain size is found and can be quantitatively explained by carrier generation at grain boundaries. In order to reduce the series resistance of the diodes, various methods to create a n+n doping profile in the recrystallized layer are investigated.
Non Alloyed Ohmic Contacts for GaAs Coplanar Mixer Diodes
Authors: Woodcock John M.
Published: March 2011

A Q-switched ruby laser has been used to anneal gallium arsenide which has either been implanted with a donor or coated with a thin layer of material containing the donor. Silicon nitride (∼500Å), germanium (∼50Å), tin (∼50Å) and silicon (∼500Å) have been used and in all cases laser annealing produces n-type doping levels in excess of 1019cm−3. Non alloyed ohmic contacts have been made on these heavily doped layers with specific contact resistances as low as 1.4 × 10−6Ω cm2. These contacts have been used in the fabrication of fine geometry coplanar mixer diodes. Ideality factors of 1.1 have been measured from the d.c. current voltage characteristics and diodes with a total capacitance of O.03pF have series resistances below 10 ohms. Matched pairs of these devices have given a 4.8dB conversion loss at 35GHz in a fin line balanced mixer.
Compositional Analysis and Electrical Property Measurements of CW Laser-Annealed InSb
Authors: Liu Yung S. , Wei C.Y. , Tantraporn W. , Chiang S.W. , Possin G.E.
Published: March 2011

Characteristics of CW Ar-ion laser annealed InSb has been studied; properties include stoichiometric composition analysis and electrical C-V measurements. The stoichiometry compositions of laser-annealed samples at different power levels and scan speeds have been studied using an electron microprobe technique. Results were compared with electrical C-V measurements using MOS structures.
Surface Temperatures Produced In Silicon Using Large Diameter Scanning Cw Sources
Authors: Gibbons J. F. , Christel L. A. , Lietoila A.
Published: March 2011

The temperature induced at the surface of a silicon wafer is calculated for both circular and rectangular scanning beams, assuming both a thermally isolated and heat sunk back surface. In the former case, the problem is one of simple uniform heating with radiative cooling at slow scan speeds. A significant thermal gradient is produced across the wafer at high scan speeds. In the latter case, a one-dimensional analysis suffices except for beam diameters less than about twice the wafer thickness, when lateral heat diffusion effects are present.
Electron Energy Distributions During Pulsed Laser Annealing and Damage of Silicon
Authors: Williams R. T. , Kabler M. N. , Long J. P. , Rife J. C. , Royt T. R.
Published: March 2011

Spectra of photoelectrons and thermionic electrons emitted from silicon during pulsed laser irradiation at energy densities encompassing the thresholds for laser annealing and damage are reported. Annealing is accomplished with a 90-nsec pulse of 532-nm light, which may be accompanied by a 266-nm probe pulse. A cylindrical mirror analyzer is used for energy resolution of emitted electrons. Time-resolved reflectivity at 633 nm verifies attainment of the high-reflectivity annealing phase. Spectral widths and total yields imply a modest electron temperature (T < 3000 K) during annealing. The data suggest that the work function of the silicon (111) face may increase about 0.6 eV upon transition to the molten phase.
Ductile Tantalum Oxide Protective Coatings
Authors: Rizkalla Hani L. , Wellinghoff Stephen T.
Published: March 2011

Amorphous, anodic Ta2O5 films of 400 A thickness deposited on deformable polymer substrates deformed by microshear banding even at 5–10% tensile strain. Electron beam evaporated Ta2O5 (EBE) were considerably more brittle in tension on the same substrates, fracturing at strains less than 1%. Even though both films were amorphous to electron diffraction the EBE vibrational spectrum in the Ta2O5 region (900 cm-1 - 400 cm-1) was more reminiscent of thermally oxidized material that appears to have greater microstructural order. A significant dynamic mechanical peak was observed at 60–90°C for both Al and Ta foils coated with either anodic or EBE Ta2O5 films. This process was assigned to relaxation of interfacial stresses induced by atomic motion in the oxide in this temperature range. In the face of the rather similar dynamic mechanical spectra we suspect that the presence of a greater Packing heterogeneity might explain the greater brittleness of the EBE films.
Contact Angle Measurements of Wetting In Pristine and Ion Implanted High Modulus Benzene Derived Graphite Fibers
Authors: de Hodgins O. C. , Dresselhaus M. S. , Uhlmann D.
Published: March 2011

Measurements are reported of the contact angles of benzene-derived carbon fibers with de-ionized water, aminopropyltriethoxy silane and du Pont 5878 polyimide solutions. Both pristine fibers and fibers implanted with 5×1012 cm-2 and 1×1015 cm-2 fluences of 31p ions were investigated. Such implantation was observed to decrease the contact angle in all three solutions. The ion implantation had no significant effect on tensile strength, but did result in increased structural disorder (as reflected in the width of the main wide angle X-ray diffraction peak) and increased surface roughness. The increased disorder and roughness are believed to be principally responsible for the observed change in wetting angle.
Kinetics of Cavity Growth In Solder Joints During Thermal Cycle
Authors: Stone Donald S. , Homa Thomas R. , Li Che-Yu
Published: March 2011

Grain boundary cavity growth in solder joints during thermal fatigue is analyzed. The stress cycle profile is estimated based on a geometrically simplified model of a ceramic chip carrier - printed circuit board assembly and a state variable equation for plastic flow in the solder.
Failure Modes of Metal Interfaces: Experimental Evidence Relating to the Effect of Chemical Species
Authors: Pashley M. D. , Pethica J. B.
Published: March 2011

The strength of an interface between two metal surfaces can be drastically affected by the presence of chemical species in the interface. The two surfaces may form the boundary between two grains inside a solid block of metal, the interface between a substrate and a metal film or the interface between two solid bodies brought into physical contact. Interface impurities such as oxygen atoms generally reduce the cohesion between the two surfaces. Conventional fracture experiments have difficulty in determining whether this results from a reduction in the interfacial energy, or a hardening of the interface, either of these making brittle fracture easier. The experiments which we have carried out by contacting two clean and characterised surfaces in ultra high vacuum, enable a direct study to be made of the change in interfacial energy and mechanical behaviour as a result of adsorbed species.

A sharp metal point of about 1μm radius of curvature is contacted against a flat metal specimen and the force of adhesion and contact area (measured from electrical resistance) are determined. The extent of ductile or elastic behaviour of the interface can be determined from the reversibility of the contact area as a function of applied load during separation.

We have shown directly from a contact experiment, that monolayer quantities of oxygen reduce the interfacial energy by a factor of three in the metal contacts studied. Interfacial ductility is only reduced by the presence of oxide layers of the order of 5nm thick.
Model Compound Approach for Polymer-Metal InterFaces: ESCA Studies
Authors: Sanda P. N. , Bartha J. W. , Silverman B. D. , Ho P. S. , Rossi A. R.
Published: March 2011

ESCA studies of two molecules which are similar in structure to the PMDA and ODA constituents of the PMDA-ODA polyimide monomer are discussed. Their interaction with in-situ evaporated Cr and Cu films are compared. The PMDA model compound interacts with Cr through the imide group, while very little interaction is observed with Cu. The ODA model compound (oxydianiline) interacts with Cr via the ether linkage and the terminal amino groups, whereas very little interaction is observed with Cu.
Oxidation of Silicides - Summary
Authors: Nicolet M-A.
Published: March 2011

Silicides of transition metals are used in two distinct ways in very large scale integrated circuits: (i) in the contact pads of individual devices on a chip, and (ii) in the interconnection lines. For the latter applications, two particular properties of the silicides make them desirable: their metallic electrical conductivity, and the possibility to produce a protective coating of SiO2 under heat treatment in an oxidizing ambient. Of those two attributes, the second one is particularly attractive because it offers inherent advantages in multilevel metallization schemes. To utilize this feature of silicides successfully, an understanding of the oxidation process is mandatory.
Interface Failure of Gold Covered SiO2 Substrate With TiW and Nb Intermediate Adhesion Layers
Authors: Liehr M. , Delrue J. P. , Herbots N. , Berghe R. Vanden , Caudano R.
Published: March 2011

In this paper, we report an electron microscopy study (SEM and TEM) of the Au-TiW-SiO2 structure annealed in ambient air up to 600°C. Scanning Auger microscopy has also been used to characterize the interfaces. Growth of pyramid- like structures was found to occur under heat treatment above 450°C. Volume increase and adhesion failure due to oxidation of the TiW layer and weak points in the Au top layer were found to be at the origin of this particular growth. Similar surface failures have been reported under oxidation at higher temperature for the tungsten silicide – SiO2 systems. According to the assumed growth mechanism, the necessary conditions for a pyramid growth have been defined and checked on another multilayer structure, that is the Au-Nb-SiO2 interface.
Multilayer Ceramics
Authors: Schwartz Bernard
Published: March 2011

Multilayer ceramics (MLC) technology is the basis for several major products today, which include capacitors and packages for integrated circuits. This technology was originally developed to produce miniature capacitors for the micromodule program. When these goals were achieved, new applications in packaging were found. The MLC technology is now the building block in IBM's medium and large computers. The current state of this technology will be described. It's advancement will require improved understanding of the sciences involved in each of the process steps. Several of these technical areas will be discus-ed, particularly the relationships among the electrical properties of the materials and the performance of the package. As the dimensions become smaller, more concern will have to be shown for the defect levels. This implies improved control of material preparation and processing.
Surface Characterization by Reflection Electron Microscopy (REM)
Authors: Hsu Tung , Cowley J. M.
Published: March 2011

Reflection electron microscopy (REM) utilizes the Bragg reflected high energy electrons to form the image of a crystal surface. Images of dislocations, atomic steps, reconstructions of surface layers of atoms and adatoms, stacking faults and twinning, superlattices, etc., have been successfully observed on a wide variety of specimens. Contrast is mainly due to diffraction and phase, which distiguished REM as a unique method for high spacial resolution and high sensitivity imaging of the surfaces of bulk specimens. REM can be effectively performed under UHV as well as under the moderate vacuum of an ordinary commercial electron microscope.