bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature Dependent Amorphization of Silicon During Self-Implantation
Authors: Maszara W.P. , Rozgonyi G.A. , Simpson L. , Wortman J.J.
Published: March 2011

We have investigated the damage which results from silicon self-implantation for the range of doses from 2E14 to 1E16 cm−2 for temperatures from 82 to 296 K for 150 and 300 keV implants. Cross-sectional TEM was used to evaluate the nature of the amorphous layer. The experimental results were correlated with computer calculated damage distributions using a Monte Carlo simulation program. The depth of amorphous-crystalline interface(s) was evaluated as a function of dose and temperature. An experimental damage energy density curve was constructed. Using the curve, a critical energy density for amorphization, Ec was calculated for the samples implanted at different temperatures. The energy was found to depend on depth and implant energy, and it increased with temperature. A study of a-c interface morphology shows no dependance on temperature within the range considered. Kinetics of dynamic annealing are discussed in conjunction with the above findings.
Metastable Alloy Formation By Ion Beam Mixing
Authors: Saris F.W. , Westendorp J.F.M. , Vredenberg A.
Published: March 2011

In Ion Beam Mixing new surface alloys are produced by a combination of vacuum deposition and ion irradiation. One may wonder what the advantages are of this combination. Indeed one may ask:

- Why not just ion implantation?

- Why ion beams instead of laser or electron beams?

- Why ion mixing instead of evaporation only?

- What phases are formed and what is the stability of ion mixed phases?

In an attempt to answer these questions the role of ion beam mixing in modern materials modification will de delineated. Areas of controversy and further development will also be illustrated.
Silicide Formation By High Dose Transition Metal Implants Into Si.
Authors: Sanchez F. H. , Namavar F. , Budnick J. I. , Fasihudin A. , Hayden H. C.
Published: March 2011

We report preliminary results of a study on silicide formation by means of high dose transition metal implants into Si (100) single crystals.

100 keV Cr+, Fe+, Co+ and Ni+ were implanted at room temperature. For the Cr+, Fe+ and Ni+ implants, no silicide formation was observed after implantation. However, both Rutherford Backscattering Spectrometry (RBS) and X-Ray Diffraction (XRD) results clearly indicated the existence of CrSi2 after the Cr-Si samples were annealed 4 hours at 550°C. In the case of the Fe+ and Ni+ implants, FeSi2 and NiSi2 were identified by XRD after annealing the implanted samples half an hour at 400°C. A layer of CoSi of about 1000 Å was observed in the as implanted Co-Si samples by both RBS and XRD.

Ni+ ions accelerated to 150 keV were implanted at 350°C. A much broader distribution and higher retention of Ni was obtained in this case, showing evidence of long range atomic diffusion. NiSi and polycrystalline silicon were observed by XRD in the as implanted samples.

The possibility of high dose ion implantation as a suitable technique for producing transition metal silicides is discussed.
Amorphisation, Crystallisation And Related Phenomena In Silicon
Authors: Williams J.S.
Published: March 2011

This review examines recently observed phenomena associated with amorphisation and crystallisation of silicon under ion bombardment and furnace annealing. Ideally, heavy ion damage should completely amorphise the silicon surface layers so that the underlying crystal can provide a perfect template for subsequent epitaxial growth. However, in practise the ion bombardment and annealing behaviour can be decidedly more complex. During ion bombardment of silicon, several correlated processes can take place depending on the target temperature and the precise bombardment conditions. These processes include: defect production; amorphisation; diffusion and segregation of defects and impurities; and ion-beam-induced (epitaxial) crystallisation. During subsequent heat treatment, amorphous layers can exhibit anomalous impurity diffusion and precipitation effects, nucleation of random crystallites, and solid phase epitaxial growth. In addition, the kinetics of the epitaxial growth process are sensitive to the type and state of implanted impurities present in the silicon. The competition between random nucleation and epitaxy is also dominated by impurity effects. Finally, correlations between all of these phenomena provide i) considerable insight into impurity and defect behaviour in amorphous and crystalline silicon, and ii) a better understanding of the amorphous to crystalline phase transition, including mechanisms of solid phase epitaxial growth.
Laser Recrystallization of InP Films on Oxidized Si Substrate
Authors: Xiqiang Li , Weiwen Zhu , Chenglu Lin , Weiyuan Wang , Shihchang Tsou
Published: March 2011

The InP films with thickness of 1-2 µm and resistivity of 10-10−3Ω-cm were sputtered on oxidized Si substrates heated at about 300°C to form as InP SOI. Using X-ray diffraction, ED, TEM, Hall and RBS, we have investigated the grain size, compositions, thermal stability and electrical characteristics of InP SOI before and after CW Ar+ laser recrystallization. The sputtered InP SOI films appear as polycrystalline and its grain size increases with increasing of irradiated laser power from 5.8 to 7.0 W at a beam diameter of 70 µm. After irradiation at 7 W the single crystal ED patterns are obtained, the mobility and carrier concentrations amount to 103cm2/Vs and 1017cm−3, respectively, and the compositions are stoichiometric.
A Study of Melting and Resolidification of Silicon-on-Insulator Structures Formed by Lateral Epitaxy
Authors: Williams D A , Mcmahon R A , Hasko D G , Ahmed H , Hopper G F , Godfrey D J
Published: March 2011

The formation of silicon-on-insulator structures, by recrystallising polycrystalline silicon films with a dual electron beam technique, has been studied over a wide range of conditions. The quality of the layers has been assessed by examining cross-sections in the SEM and optical microscopy of the surface after a Secco etch. The range of line powers which gives device-worthy single crystal material becomes greater as the sweep speed increases and as the background temperature is reduced. The extent of melting into the substrate in the seed windows and below the isolating oxide was determined from the movement of an arsenic implant. The experimental results are compared to the predictions from a one dimensional model for the heat flow.
Improved Soi Films By High Dose Oxygen Implantation and Lamp Annealing
Authors: Celler G. K. , Hemment P. L. F. , West K. W. , Gibson J. M.
Published: March 2011

Ion beam synthesis of a buried SiO2 layer is an attractive silicon-on-insulator technology for high speed CMOS circuits and radiation hardened devices. We demonstrate here a new annealing procedure at 1405°C that produces silicon films of excellent quality, essentially free of oxygen precipitates and with sharp interfaces between the Si and the SiO2.
Heavy Metal Gettering in Implanted Buried-Oxide Structures
Authors: Kamins T. I. , Chiang S. Y.
Published: March 2011

To investigate gettering of heavy metal impurities to the damaged regions surrounding an implanted buried oxide, the behavior of chrominum and copper on annealing has been investigated. Cr tends to segregate to the surface Si-SiO2 interface, although a small fraction moves to the damaged regions surrounding the buried oxide. Cu segregates to the damaged regions more readily; in addition, a large fraction of the implanted Cu moves to a location several micrometers beneath the buried oxide layer. The buried oxide does not appear to stop the movement of the Cu.
Strain and Damage in Silicon Due to a Deep Oxygen Implantation
Authors: Vreeland Thad , Jayadev T.S.
Published: March 2011

Silicon wafers, implanted with oxygen at 550°C to form a buried oxide layer have been examined with TEM and x-ray diffraction. Implantation damage increased with depth up to ~1500 Å where some amorphous regions were seen. The amorphous region extended for -4500 Å to a damaged crystalline region ~1000 Å thick. Double crystal x-ray rocking curves of the as-implanted and of annealed crystals were obtained and analyzed. The strain normal to the (100) surface in the as-implanted crystalline Si did not exceed +0.05%. After an argon anneal, the strain disappeared, leaving a crystal with a lower density of extended defects and no measureable misorientation of surface or deep layers. In marked contrast, an anneal in a hydrogen atmosphere exhibited no normal strain but contained regions above the oxide layer which differed in orientation from the substrate. The misorientation ranged up to ~0.1 degree.
The Physical and Electrical Properties of Buried Nitride Soi Structures Synthesized By Nitrogen Ion Implantation
Authors: Slawinski C. , Mao B.-Y. , Chang P.-H. , Lam H.W. , Keenan J.A.
Published: March 2011

Buried nitride silicon-on-insulator (SOI) structures have been fabricated using the technique of nitrogen ion implantation. The crystallinity of the top silicon film was found to be exceptionally good. The minimum channeling yield, Xmin' was better than 3%. This is comparable to the value observed for single crystal silicon. The buried insulator formed during the anneals has been identified as polycrystalline α-Si3 N4 with numerous silicon inclusions. This nitride, however, has been found to remain amorphous in regions at the center of the implant where the nitrogen concentration exceeds the stoichiometric level of Si3N4. Nitrogen donor formation in the top silicon layer has also been observed.
Interpretation of Uv Reflectance Measurements on Silicon-On-Sapphire By Spectral Reflectance and Spectroscopic Ellipsometry Studies
Authors: Pickering C. , Hodge A.M. , Daw A.C. , Robbins D.J. , Pearson P.J. , Greef R.
Published: March 2011

Spectral reflectance and spectroscopic ellipsometry measurements have been made on SOS wafers with haze ratings 1-5. The wavelength dependence of reflectance is dominated by surface scattering, but degraded crystallinity effects are also observed, and are significant in some samples. Analysis of dielectric function spectra using an effective medium approximation has indicated the presence of α-Si and voids in surface layers up to 300Å thick in medium haze wafers, with concentrations decreasing away from the surface. The assessment parameter normally used for SOS, UVR No., has been shown to includeboth crystallinity and scattering effects, and their relative importance cannot be determined without more detailed measurements.
Electrical Characterization of Crystallized—Silicon Thin Films
Authors: Johnson N. M.
Published: March 2011

A review is presented on the application of electrical measurements to evaluate the existence and effects of residual electronic defects in crystallized—silicon thin films. Experimental techniques include current—voltage characterization, electronbeam—induced conductivity, transient—capacitance measurements on thin—film capacitors, transient—conductance spectroscopy on thin—film transistors, and photoconductivity.
Assessment of Silicon—On—Insulator Technologies for Vlsi
Authors: Tsaur B-Y.
Published: March 2011

A high—performance, cost—effective silicon—on—insulator (SOI) technology would have important near—term applications in radiation—hardened electronics and longer term applications in submicrometer VLSI. The advantages of SOI over bulk Si technology for these applications will be outlined, and CMOS, CJFET, andbipolar device structures being developed for SOI will be discussed. The current status and future prospects of the two most promising SOI technologies —— beam recrystallization and high—dose oxygen implantation —— will be reviewed, with emphasis on such issues critical to commercialization as material quality and manufacturing feasibility.
Elimination of Subboundaries from Zone-Melting-Recrystallized Silicon-On-Insulator Films
Authors: Geis M. W. , Chen C. K. , Smith Henry I. , Nitishin P. M. , Tsaur B-Y. , Mountain R. W.
Published: March 2011

Since the introduction of zone-melting recrystallization (ZMR)for silicon-on-insulator (SOI) films, subboundaries (low-angle grain boundaries) have been the major crystalline defects in recrystallized films. By using an improved ZMR procedure, subboundaries have been eliminated over large areas. The improvements include the use of 1-µm-thick polycrystalline-Si films deposited on 2-µm-thick thermal SiO2 film (instead of 0.5-µm-thick Si and SiO2 films), a new encapsulation technique, and improved control of the thermal gradient during ZMR. Recrystallized SOI films without subboundaries contain isolated dislocations with densities <2 × 106 cm−2.
Low Temperature Polycrystalline Silicon Thin Film Devices for Large Area Electronics
Authors: Hawkins William G.
Published: March 2011

A process sequence for polycrystalline silicon NMOS logic circuitry is presented here. The fabrication sequence eliminates ion implantation steps and requires a maximum process temperature of 900°C. Low process temperature and diffusion doping may allow use of high temperature glass as substrates. Diffusion doping of large substrates eliminates expensive modification of an ion implanter. Initial Work utilized ion implantation to dope device channels before oxidation. Phosphorus channel doping is effective in the control of device threshold, based on the observation that both enhancement and depletion mode device behavior can be obtained. Boron doping is not effective because segregation of the boron into SiO2 occurs during subsequent oxidation. The results obtained from ion implantation doping show that functioning NMOS gates can be fabricated. In fact, it was discovered that undoped polycrystalline silicon channels provide suitable enhancement mode devices, while lightly phosphorus doped channels yield depletion mode devices. A process sequence based solely on phosphorus diffusion is then demonstrated.
Capping Techniques for Zone-Melting-Recrystallized Si-On-Insulator Films
Authors: Chen C.K. , Pfeiffer L. , West K.W. , Gels M.W. , Darack S. , Achaibar G.
Published: March 2011

To prepare silicon-on-insulator (SOI) films by graphite-strip-heater zone-melting recrystallization (ZMR), a capping technique must be used to insure wetting by the molten Si zone. We have demonstrated two new capping techniques that result in reproducible wetting without degrading the crystallographic texture of the recrystallized film: annealing SiO2- capped Si films in NH3 and depositing two SiNx layers with carefully controlled compositions on the SiO2 capping layer. Wetting is promoted by the incorporation of trace amounts of nitrogen at the Si-SiO2 interface. Both N implantation experiments and Auger spectroscopy studies establish that the presence of less than a monolayer of nitrogen at this interface is sufficient to insure wetting.
A Seeded Channel Approach to Silicon-On-Insulator Technology
Authors: Ting C. H. , Baerg W. , Lin H. Y. , Siu B. , Hwa T. , Sturm J. C. , Gibbons J. F.
Published: March 2011

A seeded channel approach was developed to avoid the short comings of the conventional SOI structure such as grain or sub-grain boundaries in the channel region, floating substrate effects, etc. In this approach, the gate of each FET is located above its own seed window to insure that single crystalline material is obtained for the channel region. The source and drain regions, however, are located in the recrystallized silicon over Si02 for improved isolation and minimizing junction capacitance. Recrystallization was obtained in 4" silicon wafers by using an Ar laser and a computer controlled X-Y stage with heated substrate holder. Problems encountered in laser recrystallization, such as, reflectivity variations over seed and SOI regions, surface ripples, pittings, etc., were eliminated by optimizing the thin film thickness of the isolation oxide, polysilicon, and the capping oxide. This technology was used successfully to fabricate FET devices using a standard production n-MOS process. Good device characteristics were obtainred using 400Å gate oxide and channel length ranging from 1um to 50um. The measured electron mobility in the channel region is, however still lower than the ideal bulk values.
Electronic Structure Of Silicide-Silicon Interfaces
Authors: Bisi O.
Published: March 2011

Significant understanding of the processes occurring at the interface between transition metal ultrathin overlayers and silicon has been achieved in recent years. In general these interfaces are highly reactive and the formation of an interfacial suicide compound takes place. The reaction at the near-noble metal-silicon interface can occur even at liquid nitrogen temperature. Furthermore the reaction products can give rise to epitaxial interfaces. How can the covai ent bonds in silicon be broken at such a low temperature and eventually give rise to an epitaxial interface are intriguing questions, which cannot be answered without a full understanding of the electronic and atomic processes involved in the interface reaction.

Theoretical investigation‘through band structure calculations allows us to understand the modifications of the suicide electronic states in the interface region. Assuming various interface geometries (e.g. epitaxial growth or interstitial interdiffusion) the effect of different atomic processes on the electronic properties is analysed and available photoemission and Auger spectroscopie experimental informations are interpreted. The role of both electronic states and atomic processes in determining the interface physical properties is discussed.
Early Stages Of Reaction Between Amorphous Ni-Nb And Crystalline Au Films
Authors: Dobisz E. A. , Craighead H. G. , Perepezko J. H. , Wiley J. D. , Doyle B. L. , Peercy P. S.
Published: March 2011

Thin film interactions between a-(Ni-Nb) and polycrystalline Au over-layers have been studied with high depth resolution (≤1.7nm) Rutherford backscattering (RBS) and TEM to obtain information on the early stages of reaction at the interface. The RBS spectra from Au indicated that the interdiffused samples consisted of two layers: an Au-Nb binary layer on the surface and a ternary Au-Ni-Nb compound layer beneath the binary layer. The growth kinetics of the ternary compound layer differed in samples which had been relaxed prior to Au deposition from the kinetics for unrelaxed samples. Furthermore, cross section TEM micrographs showed that relaxed and unrelaxed samples exhibit different microstructures after the early stages, of annealing. We interpret this result to indicate that the reaction stages in relaxed samples are not as advanced as those in the unrelaxed samples.
Reaction Of Amorphous And Crystalline Alloys With Silicon
Authors: Hung L. S. , Wang S. Q. , Mayer J. W. , Saris F. W.
Published: March 2011

The reaction of Ni- refractory metal alloys with silicon has been studied by backscattering spectrometry and transmission electron microscopy. The analysis of the as-deposited sample revealed solid solutions for Ni-Cr and amorphous phases for Ni-Ta and Ni-Ti. In situ annealing resulted in crystallization of Ni43 Ta57 at 750 °C, a value above the reaction temperature of the alloy with silicon. The amorphous alloy of Ni48Ti52 was transformed into the equilibrium compound of NiTi at 450 °C, much below the reaction temperature. Phase separation has been observed in the Ni-Cr and Ni-Ta systems with a Ni- silicide layer next to the Si substrate and a refractory disilicide layer on the other side. In contrast, Si reacts with the NiTi compound to form a uniform mixed layer with a composition of NiTiSi2. The different behavior is explained based on considerations of both thermodynamic and kinetic terms.
In Situ Ellipsometric Studies of Palladium Silicide Formation
Authors: Kelso S. M. , Nemanich R. J. , Doland C. M.
Published: March 2011

We have studied the formation of palladium suicide on clean silicon <111> surfaces using in situ spectroscopie ellipsometry. Pd films of thicknesses from 5 to 50 A were studied both as deposited and after annealing to complete the reaction to Pd2Si. The measured dielectric function spectra were analyzed to determine the amounts of Pd2Si and unreacted Pd. Evidence of Pd-Si solid state reaction was detected after all depositions. In the as-deposited films the fraction of suicide increased with the thickness, up to about 40% for the thickest films (50 Å Pd), while the annealed films were completely reacted. These results are consistent with earlier Raman spectroscopy studies.
Epitaxial Growth of CaxSr1−xF2 Layers on CaF2 by Vacuum Evaporation
Authors: Norton Nicholas G. , Knight K. S.
Published: March 2011

The evaporation and epitaxial growth on single crystal CaF2 substrates of CaF2/SrF2 mixtures are investigated. The evaporated films are studied with X-ray diffraction and optical microscopy.

X-ray diffraction results show that the evaporation of yCaF2 + (1 - y)SrF2 mixtures from a single boat, with y in the range 0 to 1, result in single phase, mixed crystals of composition CaxSr1−xF2. If Vegard's law is assumed to apply it is found experimentally that the film composition is the same as that of the source.

For the evaporation of CaF2 and SrF2 onto cleaved CaF2 crystals it is shown that the best quality epitaxial films are obtained at substrate temperatures of∼400°C. At temperatures <400°C there is some broadening of the X-ray diffraction spots from the overlayer compared with those from the substrate. At temperatures>400°C there is a tendency for the epitaxial films to delaminate from the substrate.
Reaction And Interdiffusion at III-V Compound Semiconductor-Metal Interfaces
Authors: Brillson L. J.
Published: March 2011

The characterization of III-V compound semiconductor-metal interfaces by surface science techniques has led to new relationships between interfacial chemistry and Schottky barrier formation. These and recent results on ternary alloy III-V compounds suggest a greater control of Schottky barrier heights by atomic scale techniques and advanced III-V materials than previously believed.
Phase Formation Sequence In The Pd-Gaas System
Authors: Sands T. , Keramidas V. G. , Yu A. J. , Yu K. M. , Gronsky R. , Washburn J.
Published: March 2011

The morphological aspects of ternary phase formation during the Pd-GaAs reaction have been studied by application of transmission electron microscopy (TEM) and Rutherford backscattering (RBS) techniques. The TEM images show that the first product phase, “phase I”, forms during deposition of Pd onto (100) GaAs and exhibits the preferred orientation [0001]I ∼ // [011]GaAs. In the presence of unreacted Pd, the second phase, “phase II”, nucleates at large-angle grain boundaries in the phase I film as the annealing temperature increases above ∼ 250°C Energy dispersive analysis of x-rays and RBS suggest that both phases I and II have nominal compositions in the range of Pd3GaAs to Pd4GaAs.
Photochemical Organometallic Vapor Phase Epitaxy Of Mercury Cadmium Telluride
Authors: Morris B. J.
Published: March 2011

Because of the difficulty in preparing single-crystalline Hg1−xCdx Te with adequate control of properties for detector array manufacturing, the emphasis in material development has shifted to epitaxial techniques, such as molecular beam epitaxy (MBE), liquid phase epitaxy (LPE), and organometallic vapor phase epitaxy (OMVPE, sometimes called MOCVD). Each of the epitaxial techniques thus far reported has fundamental limitations such as a requirement for high growth temperature (LPE and OMVPE) or low growth rates (MBE). We report here preliminary results on a new technique, called photochemical organometallic vapor phase epitaxy (POMVPE), which apparently does not have the limitations of other epitaxial methods for growing Hg Cd Te films.
Non-Alloyed Ohmic Contacts to n-GaAs Using Epitaxial Ge Layers
Authors: Sawada T. , Chen W. X. , Marshall E. D. , Kavanagh K. L. , Kuech T. F. , Pai C. S. , Lau S. S.
Published: March 2011

Alloyed ohmic contacts (i.e. Au-Ge-Ni) to n-GaAs lead to non-planar interfaces which are unsuitable for devices with shallow junctions and small dimensions. In this study, the fabrication of non-alloyed ohmic contacts (via solid state reactions) is investigated. A layered structure involving the solid phase epitaxy of Ge using a transport medium (PdGe) is shown to produce low (1 — 5 × 10∼6Ω cm2) and reproducible values of contact resistivity. The resultant interface is shown to be abrupt by cross-sectional transmission electron microscopy.
Improved Ohmic Contacts to n-Type GaAs, Using Oiboride Diffusion Barriers
Authors: Shappirio Joel R. , Lux Robert A. , Finnegan John J. , Fox Donald C. , Kwiatkowski Joseph H.
Published: March 2011

Ohmic contacts employing Au/Metal/Au/Ge/Ni (Metal=Ni or. TiB2) to n-type GaAs have been investigated. Alloying of the contacts, performed by both optical (rapid thermal) and strip heater methods, resulted in very low specific contact resistivities for the samples employing the TiB2 diffusion barrier. Such contacts are shown to be stable on aging at 350C for 180 hours.
Electrical Study of Schottky Barriers on Cleaved InP and GaAs (110) Surfaces
Authors: Newman N. , van Schilfgaarde M. , Kendelewicz T. , Spicer W. E.
Published: March 2011

We have performed a systematic study of the electrical properties of a large number of metal/n-GaAs and metal/n-InP diodes. Diodes were fabricated on clean cleaved InP and GaAs (110) surfaces in ultra-high vacuum with in-situ metal deposition of Cr, Mn, Sn, Ni, Al, Pd, Cu, Ag and Au. Using current-voltage (I-V) and capacitance-voltage (C-V) measuring techniques, we were able to obtain very reliable and consistent determinations of the barrier height, θ/b, and ideality factor, n. All of the metal-semiconductor systems formed on lightly doped (< 5×1016/cm3) substrates were characterized by near-unity (1.05) ideality factors.

The effects of doping on the electrical characteristics of the n-GaAs diodes were investigated. A decrease in the effective I-V barrier height, an increase in the ideality factor in forward bias and a strong voltage dependence on the thermionic emission currents in reverse bias were found for diodes formed on the more heavily doped samples. These changes are essentially metal-independent, but depend strongly on the doping of the substrate. The characterization (and elimination in some cases) of peripheral leakage currents from the thermionic emission current for the n-GaAs systems was found to be essential in obtaining consistent results in our work and in reinterpreting some of the prior work in the literature. The dominant leakage current in the GaAs diodes flows through a small area, low barrier at the periphery of the device and can be eliminated by mesa etching.
Uv-Ozone Cleaning of GaAs (100) Surfaces for Device Applications
Authors: Solomon J. S. , Smith S. R.
Published: March 2011

GaAs (100) substrates were subjected to UV-ozone, wet chemical, and thermal treatments prior to deposition of Ni contact structures. The use of UV-ozone showed marked improvement in the electrical characteristics compared to the wet chemical and thermal treatments alone. The major effect of UV-ozone is the nondestructive removal of carbonous contaminants. Results of C-V and I-V barrier height measurements on Ni contact structures fabricated on the treated surfaces are presented.
Electrical Properties of Epitaxial Silicide-Silicon Interfaces
Authors: Tung R. T. , Levi A. F. J. , Gibson J. M. , Ng K. K. , Chantre A.
Published: March 2011

The Schottky barrier heights of single crystal NiSi2 layers on Si(111) have been studied by current-voltage, capacitance-voltage and activation energy techniques. Near ideal behavior is found for Schottky barriers grown on substrates cleaned at ∼820°C in ultrahigh vacuum. The Fermi level positions at the interfaces of single crystal type A and type B NiSi2 are shown to differ by ∼0.14 eV. Transmission electron microscopy demonstrated the epitaxial perfection of these suicide layers. At a cleaning temperature of 1050° C, the near surface region of lightly doped n-type Si was converted to p-type. The presence of a p-n junction was directly revealed by spreading resistance measurements and resulted in a high apparent Schottky barrier height (≥0.75 eV) which no longer bears immediate relationship to the interface Fermi level position.
Silicide-Silicon Interface States
Authors: Yang E. S. , Wu X. , Evans H. L. , Ho P. S.
Published: March 2011

The existence and nature of localized states at metal-semiconductor interfaces are long-standing scientific issues that have not been resolved. As device dimensions continue to shrink and packing density continues to increase, interfaces at silicide-silicon contacts will be increasingly influential in determining the circuit behavior. Characterization of these interfaces, whether as ohmic contacts or rectifying junctions, is a necessity for microelectronics. Therefore, the study of silicide-silicon interfaces are important both scientifically and technologically. In this talk, we shall review the theoretical models of the Schottky barrier and the importance of interface states. We shall then introduce available experimental tools for interface state studies. In particular, we shall discuss the measurement of silicide-silicon interface states by an accurate-phase capacitance spectroscopy (APCS). Some of the devices were fabricated with standard chemical cleaning before metal evaporation. Others were prepared in an UHV chamber with heat cleaning before metal deposition. For palladium suicide diodes, the behavior of both chemically-cleaned and UHV-prepared samples is similar. The peak position of the capacitance spectrum correlates with the barrier height, and the magnitude of the peak decreases by a factor of three after annealing. In the case of nickel suicide diodes, a comparison between epitaxial and non-epitaxial interfaces shows much lower interface state density for the former. Experimental data indicate that suicide formation and interfacial perfection are important in specifying the Fermi level.
Electrical Characterization of the Oxide-Silicon Carbide Interface by MOS Conductance Technique
Authors: Chaudhry M. I. , Berry W. B.
Published: March 2011

The electrical properties of the SiO2/SiC interface were studied using the conductance vs voltage (G-V) data for the metal-oxide-SiC (MOS) structure. It was found that the dry oxide contained too mjch charge either at the oxide-SiC interface or within the oxide films to obtain useful data. On the other hand the wet oxide invariably resulted in better capacitance and conductance data. The capacitance-voltage data showed that the SiC surface exhibited accumulation, depletion or inversion when the appropriate gate bias was applied. The conductance-voltage data indicate electronic surface states at the oxide-SiC interface. From this conductance data the interface state density has been estimated.
Epitaxial Growth Of Platinum-Group Metal Silicides On (111) SI
Authors: Chang Y. S. , Chu J. J. , Chen L. J.
Published: March 2011

Epitaxial ruthenium, osmium, rhodium and iridium suicides have been successfully grown on silicon. Electroless chemical plating was used to deposit platinum-group metal thin films on silicon. Two step annealing was found to be effective in inducing the growth and improving the quality of the epitaxial suicide on silicon.

Transmission electron microscopy was applied to characterize the microstructures and determine the orientation relationships between epitaxial suicides and substrate Si. The compositions of deposited films were determined by scanning Auger electron spec-troscopy combined with depth profiling technique. The percentages of phosphorus were found to be in the range of 2–3 at. %.
Dlts Study of Oxide Traps Near the Si-SiO2 Interface
Authors: Vuillaume D. , Bourgoin J. C.
Published: March 2011

We have used the DLTS (Deep Level Transient Spectroscopy) technique to characterize the traps of the oxide layer near the Si-SiO2 interface. Using the so-called saturating pulse DLTS, no saturation is observed when all the fast interface states are filled. This unusual behavior is interpreted by taking into account tunneling emission from oxide traps situated near the Si-SiO2 interface. We show how the deconvolution between interface states and oxide traps is allowed by introducing a model of tunneling emission from oxide traps into Si substrate, for the derivation of the DLTS response. By this way a depth localisation of these oxide traps is obtained : about 10 to 30 Å from the interface. The experimental study of the filling kinetics allows the determination of the concentration of these oxide traps (≈ 107 to 108 cm-2) and their associated tunneling capture cross-section (≈ 10-22 to 10-21 cm2). The validity of the model and measurements is rapidly discussed.
Microstructure and Magnetic Properties of CoCrTa Thin Films
Authors: Robinson C. J. , Howard J. K.
Published: March 2011

The addition of Ta into thin sputtered films of CoCr greatly affects the microstructure and magnetic properties. Grain size, crystallographic preferred orientation and hysteresis parameters have been studied using transmission electron microscopy, electron diffraction, X-ray diffraction, polar Kerr effect and vibrating sample magnetometry techniques. Crystallographic preferred orientation is enhanced and is accompanied by increased perpendicular magnetic anisotropy. An extremely fine-grained microstructure is produced giving rise to films which show no morphological growth features. Thus the observed magnetocrystalline anisotropy is not attributed to columnar growth. Orientation in these films can be further increased by using under-layers of non-ferromagnetic CoCrTa alloys. The mechanism by which this occurs is discussed.
Correction Method for Ion Yield Transients in the Near Surface Region of Sims Depth Profiles
Authors: Bryan S. R. , Linton R. W. , Griffis D. P.
Published: March 2011

As solid state device features continue to decrease in size, it has become more important to characterize dopant concentrations within the first several hundred angstroms of the surface. Secondary ion mass spectrometry (SIMS) is the technique of choice for dopant depth profiling due to its high sensitivity and good depth resolution. In order to increase the sensitivity of SIMS, electropositive elements (e.g. oxygen) or electronegative elements (e.g. cesium) are used as primary ion species to enhance positive or negative secondary ion yields, respectively. This has the disadvantage, however, of causing secondary ion yields to vary by up to several orders of magnitude over the first few hundred angstroms of a depth profile as the implanted primary ion concentration increases [1,2]. Secondary ion yields stabilize once the primary ion reaches a steady state concentration, which occurs at a depth proportional to the range of the primary ions in the solid. This ion yield transient artifact hinders quantification of dopant concentrations until the primary ion concentration reaches steady state.
The Effect of the Oxide Interface on the Material and Electrical Properties of Polysilicon Contacts
Authors: Burk Dorothea E. , Newkirk Joseph W. , Jo Myung-Suk
Published: March 2011

A strong correlation has been found between the electrical, compositional and structural properties of the polysilicon contact and its interface with the heavily doped pol isi 1-emitter of a transistor. The integrity and thickness of the oxide interface is a major factor for improving the observed performance. Transistors for which the polysilicon was also the diffusion source for the emitter were studied.
Amorphous Silicon Ultra Thin Base Bipolar Phototransistor with High Performance (β=12, τx ≤30μs)
Authors: Chang C. Y. , Wu B. S. , Fang Y. K. , Lee R. H.
Published: March 2011

An n+ /i/p /i/n amorphous silicon bipolar transistor has been successfully fabricated with a current gain of 12 and a response speed of 30 yS This new structure of bipolar transistor has a very thin base (200Å), therefore, high gain and high speed is obtainable. This device has a very promising applications as a flat panel display transistor and a phototransistor in photosensing element/array and photo coupler. Electrical and optical characteristics have been extensively investigated. Theoretical model and experimental results are plausibly in good agreement.

Variation from the fundamental structure is also been developed, such as the Schottky emitter Al/i/p /i/n bipolar transistor.
Influence of Al Thin Film Properties on Wire Bondability of Semiconductor
Authors: Kobayashi M. , Hirota J. , Watanabe N. , Machida K.
Published: March 2011

It is required for the reliable semiconductor to control high junction quality in wire bonding.

It is expected that the Al film properties may considerably affect the junction quality. Yamamoto et al. studied the effects of Al film properties on the bondability in wire bonding by thermocompression bonding system, and disclosed that the breakability of oxide film on the Al is a key factor. [1]

In this report, effects of fabrication condition, properties and bond-ability of Al thin film were investigated in wire bonding by thermosonic bonding system. As a result, it has clarified that concentration of impurities in the Al film is an extremely influential factor for the stability of adhesion and the expansion of alloying region in the junction boundary, that is, for the improvement of junction quality.
Decohesion of Thin Films From Ceramic Substrates
Authors: Cannon R. M. , Fisher R. M. , Evans A. G.
Published: March 2011

Decohesion of thin films from ceramic or semiconductor substrates is strongly influenced by internal stresses in films and stress concentrations from edges or flaws as well as by interfacial fracture energy. Residual stresses can cause spontaneous delamination, splitting and curling of films under tension or delamination, buckling and spal ling of films under residual compression, even with good interfacial bonding. Delamination behavior is considered using simple fracture mechanics models, supplemented with preliminary measurements of interfacial fracture energies. Formation conditions largely control internal stresses in films; whereas fracture energies are dictated by interfacial chemistry and mechanical factors such as plasticity.
An Investigation of The Bond Between Layers of Consolidated Amorphous Ribbon (Powercore™ Strip)
Authors: Raybould D. , Diebold A.
Published: March 2011

Thin amorphous metal ribbons can be bonded together to form a thick strip which remains amorphous. This, PowercoreTM strip, has similar magnetic properties to the annealed thin ribbon and so is a direct substitute for silicon steel in power transformers. Its good properties are partially a result of the nature of the bond between the layers of ribbon. This paper reports on a study of this bond by Auger microscopy and laser acoustic microscopy.
Correlation between Fracture Mechanical and Atom Probe Investigations on Metallic Glass Ribbon
Authors: Calvo M. , Menand A. , Osterstock F. , Chermant J.L.
Published: March 2011

Metallic glasses have good mechanical and magnetical properties. However they embrittle after annealing and/or low temperature testing. In this paper, we describe the rupture of atom probe tips using fracture mechanical measurements. We found boron rich areas which seem to be interconnected and more numerous after annealing and act as crack nuclei. The good correlation between the calculated and the measured size of the critical defect seem to confirm that the boron segregations are on the origin of embrittlement and gives good ground for further straightforward investigations.
Formation of Quasicrystals In Rapidly Solidified Al Alloys
Authors: Schaefer Robert J. , Bendersky Leonid A
Published: March 2011

Electron beam surface melting has been used to study Al-Mn and Al-Mn-Si alloys subjected to a wide range of solidification conditions. Several of the reported equilibrium intermetallic phases are not found even at moderate growth rates. Beyond a composition-dependent critical velocity the equilibrium phases are all replaced by the quasicrystalline icosahedral and decagonal (T) phases. The icosahedral phase is favored over the T phase by higher solidification velocities. The addition of Si to Al-Mn alloys eliminates the T phase, but does not significantly facilitate the formation of the icosahedral phase by electron beam melting because the ternary α and β phases of Al-Mn-Si are able to grow rapidly into the electron beam melts.
Formation and Thermal Stability of Quasi Crystalline and Other Metastable Al-RICH Al-Mn Phases
Authors: Quan M.X. , Giessen B.C.
Published: March 2011

RSP of Al-rich Al-Mn alloys is known to produce several metastable phases, including (with increasing Mn content) supersaturated Al solid solution and two non-crystallographic phases, identified in the literature as an icosahedral phase (I) and a (probably) decagonal phase (T) with translational symmetry in one direction. The formation of these phases in the composition range from 8 to 30 at. pct. Mn has been studied in melt-spun and arc-furnace quenched alloys. The thermal transformation characteristics of all metastable phases were measured by DSC; transformation temperatures, enthalpies and activation energies were determined. At compositions from 17 to 20 at. pct. Mn, two transformations were observed. Noteworthy results include: smeared out (slow-onset) reactions, transformation temperatures dropping sharply toward lower Mn contents, transformation enthalpies rising steeply in the same range, and activation energies ranging from ~40 kcal/gmol for the low-temperature process (at ~763 K) to ~80 kcal/gmol for the high temperature process (~883 K).
A Study of Amorphous Erbium-Based Alloys Formed by Near-Isothermal Cold-Rolling of Elemental Composites
Authors: Atzmon Michael , Unruh Karl M. , Politis Constantin , Johnson William L. , Keck W. M.
Published: March 2011

We report the formation of single-phase amorphous Cu-Er and Ni-Er alloys in bulk form by cold-rolling of composites prepared from elemental foils. As for previously reported cases of metallic glass formation by solid-state reaction, the driving force for the reaction is the negative enthalpy of mixing of the constituent elements. It occurs during deformation close to room temperature. Amorphous Cu7 2 Er2 8 was also produced by high-energy ball-milling of the elemental powders as well as by sputtering and liquid quenching. The alloys obtained were characterized by means of differential scanning calorimetry and x-ray diffraction. The crystallization behavior observed and the radial distribution functions obtained showed good agreement between the alloys prepared by different methods.
Deposition of TiN Films by Reactive Sputtering with Targets Facing Type of High Rate Sputtering
Authors: Naoe M. , Hoshi Y.
Published: March 2011

TiN films lμm thick were deposited on SKH55 alloy substrate at various substrate bias voltage by a reactive sputtering of Ti target in a mixture of Ar (1 mTorr) and N2 (1 mTorr) with a Target Facing type of high rate sputtering apparatus. The color of the film changes in the order of yellow, golden, silver and golden as the substrate bias voltage increases from 0 to 200 V. The reflection ratio and Vicker's hardness of the film also changes with the bias voltage. Besides, the change of the reflection factor corresponds well to the change of theVicker's hardness of the film. The films with silver color and maximum reflection ratio which are obtained at a rf bias voltage around 100 V, have the largest value of the Vicker's hardness about 3500. While, the films with golden color and small reflection factor, which are obtained at both rf bias voltage around 80 V and 150 V, have the lowest Vicker's hardness of about 1500.
Surface Treatment of Titanium Using Lasers
Authors: Mordike B.L. , Bergmann H.W.
Published: March 2011

Thermochemical treatments of titanium surfaces by laser are presented and the beneficial effects attainable eg wear resistance, corrosion resistance etc., discussed. It is shown that it is possible to produce titanium surfaces with load bearing capability.
Particle Coarsening of Dispersoids In Rapidly Solidified Ti-5Sn-3Y
Authors: Lu Y.Z. , Giessen B.C. , Whang S.H.
Published: March 2011

Rapidly solidified Ti alloys containing rare earth metal dispersoids, such as La or Er, have excellent resistance to coarsening at elevated temperature (700–900°C). In particular, the coarsening of the dispersoid particles in RSP Ti-5Sn-3Y was studied; these particles were found to be Y5Sn3. The measured growth kinetics were found to be compatible with the modified LSW model; it was concluded from the observed parameters that in this alloy the diffusion rate of Y is the rate determining factor, providing a measurement of the diffusion coefficient of Y in a Ti matrix and yielding its activation energy Q = 272 kJ/mole.
Transition from A Planar Interface to Cellular and Dendritic Structures During Rapid Solidification Processing
Authors: Laxmanan V.
Published: March 2011

Microstructural transitions occurring during solidification processes may be described in terms of three dimensionless parameters, s, p and σC, which include among them various processing variables and relevant material constants. The dimensionless parameter, s, in particular offers a convenient description of both planar-cellular and cell-dendrite transitions. The relationships between σC, s and p predicted by various dendrite growth models have been summarized.
Creep Deformation of Ultrafine Grained Ni7 5B1 7Si8
Authors: Nussbaum Gilles , Ast Dieter G.
Published: March 2011

The creep behavior of the fine grained, intermetallic superplastic alloy of overall composition Ni7 5 B1 7Si8 prepared by crystallizing an amorphous precursor was studied in the temperature range between 500 and 615°C, the stress range between 36 and 800 MPa, and for grain sizes between 6.8 and 1.12*10−5 mm. The strain rates measured varied between 10−7 and 6*10−5 sec−1.

Two different creep deformation mechanisms were observed. At low applied stresses, the material deformed in a diffusion controlled mode, with proportional to σ1. No dislocations developed in the grains, and the activation energy for creep was 4 eV. This value is higher than the self-diffusion of Ni in Ni (the principal constituent in the alloy) in agreement with observation in other Ni based alloy systems. At high applied stresses, a second mechanism became rate limiting. The activation energy of this process is about 0.6 eV and dislocations develop in the interior of grains when this mechanism operates.

The transition between the two regimes is grain size and temperature dependent and occurs at about 400 MPa at a deformation temperature of 550°C and a grain size of 6.8 10−5 mm. An analysis of the grain size dependence of creep strain rate as well as its absolute value indicates that the low stress regime is Coble type creep.
Fracture Processes in Fully Crystallized Co84Nb10B6 Metallic Glass
Authors: Megusar Janez , Vargas Tina , Grant Nicholas J.
Published: March 2011

Fracture processes have been studied in a fully crystallized Co84Nb10B6 glass, with the mean grain size ranging from 43 nm to 0.65 μm. Tensile tested specimens with a mean grain size≥ 0.3 μm showed a ductile (dimple) fracture with microvoids initiated at the boride-cobalt matrix interfaces. As the mean grain size (more correctly, the corresponding mean free path of the deforming cobalt phase) was ≤ 0.1 μm, the fracture process may be similarly initiated by the microvoid formation at the boride-cobalt interface. However, one-to-one correspondence between dimples and boride particles may not be preserved. As a result, dimples become more shallow and may include several boride particles instead. Although the fracture surface of the brittle fine grained Co84Nb10B6 alloy gives an appearance of a cleavage fracture on a macroscale, it is distinctly different, by allowing for the microvoid formation on a microscale.