bluuebunny/crossref_metadata_2025 huggingface dataset:
Amorphization of Zr3Al by Hydrogenation and Subsequent Electron Irradiation
Authors: Meng W. J. , Koike J. , Okamoto P. R. , Rehn L. E.
Published: March 2011

1-MeV electron irradiation of hydrogenated Zr3Al (Zr3AlH0.96) at 10K is studied. A more than 20 fold reduction in the critical dose required for complete amorphization is observed for the hydrogenated specimen as compared to the un-hydrogenated Zr3Al under identical irradiation conditions.
Microstructures in Sic and Si3N4Implanted with Ti and Heat Treated
Authors: Vardiman R. G.
Published: March 2011

Bulk SiC and Si3N4have been implanted with Ti at room temperature, and subsequently vacuum heat treated between 800° and 1100°C. All specimens were backthinned by ion milling and examined in TEM. SiC becomes amorphous on implantion, and develops a fine dispersion of TiC precipitates up to 800°C. At 900°C recrystallization has begun, possibly nucleated by the TiC particles. Si3N4shows fine TiN particles in an amorphous matrix even as implanted. This structure is retained up to 900°C. At 1000°C, regrowth of the Si3N4apparently from the substrate begins, and the TiN particles also grow as large as 200nm.
Tribology of Amorphous Alloys Formed With Ion Beams
Authors: Follstaedt D. M. , Knapp J. A. , Pope L. E.
Published: March 2011

The changes in friction and wear properties (i.e., tribology) of steels due to thin surface alloys formed by ion beams are surveyed, and considered in light of their microstructures. Amorphous alloys containing both Ti and C are found to give superior performance in comparison to alloys with N, B, C, P or Ti. All the amorphous layers reduce friction, but the duration of benefits and wear resistance at high loads vary with composition. By examining similar amorphous alloys with Ti alone or C alone, the critical roles played by each in resisting wear are demonstrated. Amorphous alloys with Ti and C appear to be quite hard.
The Relationship Between Crystal Structure and Hardness of Nitrogen Implanted Iron Surface Layers
Authors: Fujihana Takanobu , Okabe Yoshio , Iwaki Masaya
Published: March 2011

A study has been made of the relationship between crystal structure and hardness of N-implanted Fe-surface layers. The substrates used were polycrystalline Fe-sheets 1 mm thick with a purity of 99.9 %. The ion implantation of 14N+ was performed with doses ranging from 7.5×1016 to 1×1018 ions/cm2 at an energy of 100 keV. The substrate temperatures during implantation were kept at -40, 20, 100 and 200 °C. The crystal structure of N-implanted layers was identified by X-ray diffraction method (XRD). The near surface hardness was measured by a Knoop hardness tester. The XRD patterns revealed that the iron-nitride peculiar to each implantation condition was formed, and the iron-oxide was embedded in the nitrides in case of higher temperature implantation. N-implantation led to hardness increase, whose degree also depended on implantation conditions. The comparison between the structure and hardness of implanted layers indicated that, among the phases of iron-nitrides produced by 20 °C implantation, ε-phase is the hardest and the γ-Fe203 and γ'-Fe4N formed by 200 °C implantation are harder than the ε-phase nitrides. These results are discussed with respect to the surface composition estimated by Rutherford backscattering spectrometry (RBS) using 1.5 MeV 4He+-ions.
Microstructural Studies of Iad and PVD Cr Coatings by Cross Section Transmission Electron Microscopy
Authors: Cheng C. C. , Erck R. A. , Fenske G. R.
Published: March 2011

Cross section transmission electron microscopy was used to study the microstructure and interface structure of Cr films deposited by ion-assisted deposition as a function of the incident ion energy. High-energy ion bombardment (1 keV) was found to enhance the adhesion of the deposited film owing to the formation of an intermixed layer, whereas deposition with lowenergy ions (100 eV) was found to reduce or eliminate grain boundary porosity. A tailored Cr film with excellent adhesion and no grain boundary porosity was deposited by combining highand low-energy ion bombardment.
Passivation of GaAs Laser Mirrors by Ion-Beam Deposited Al2O3
Authors: Webb D. J. , Dietrich H. -P. , Gfeller F. , Moser A. , Vettiger P.
Published: March 2011

The use of ion-beam sputtered Al2O3 to passivate the mirrors of semiconductor injection lasers is described. Dense films, which offer considerable protection against corrosion, can be deposited without damage to the crystal surface. The overall quality of the passivation is demonstrated by long-term stress testing of the lasers.
Ion Beam assisted Deposition of Titanium Nitride
Authors: Hubler G. K. , Vanvechten D. , Donovan E. P. , Kant R. A.
Published: March 2011

The composition of titanium nitride films prepared by ion beam assisted deposition was studied as a function of the partial pressure of N2 gas in the deposition volume, and as a function of the impingement 'ratio of nitrogen ions (500 eV) to evaporated titanium atoms. The amount of nitrogen incorporated from the ambient gas was derived by subtraction of the fraction introduced by the ion beam. It is shown that the primary effects of ion bombardment are an increase in the sticking coefficient and a reduction in the number of active surface adsorption sites.
Influence of Phosphorus Dopant Concentration on Recrystallization of Buried Amorphous Layers in SI(100) Produced by Channeled Implants
Authors: Schreutelkamp R. J. , Janssen K. T. F. , Saris F. W. , Westendorp J. F. M. , Kaim R. E.
Published: March 2011

Buried amorphous layers are produced in Si(100) by implantation of 100 keV P+ and Si+ ions under channeling condition along the <100>-direction. Rutherford Backscattering Spectrometry in combination with channeling shows that a continuous buried amorphous. layer with a thickness of 1300 Å results under a crystalline toplayer with a thickness of 600 Å. After Solid Phase Epitaxy a highly concentrated defect layer remains for all implants at the depth where the two amorphous/crystalline interfaces of the buried amorphous layer meet. Planar channeling along (100)-direction shows that dislocation loops are present after SPE regrowth at the ‘interface’ of the two crystalline regions for all implants. The size of the dislocation loops becomes smaller in the presence of phosphorus. Moreover, channeling analysis shows that in case of Rapid Thermal Annealing treatment in addition to the SPE regrowth process the defect structures present after full recrystallization can be more easily dissolved in case of the phosphorus implants as compared to the silicon self implant
Influence of the Implanted Species on the Residual Damage After Hot Implants in Silicon
Authors: Calcagno L. , Spinella C. , Catania M. , Campisano S. U. , Foti G. , Ferla G. , Rimini E.
Published: March 2011

Damage formation during hot implants of 600 keV As or Ge ions into Si was investigated by changing the target temperature (>150 °C) and the ion fluence. The defect distributions, as obtained by channeling analysis, are characterized by a gaussian shape whose maximum coincide with the peak of the energy density deposition and with a width of 200 nm. The amount of damage is a factor of two higher for Ge than for As ion implants, and a similar result was found for the damage created by Ge implants into bare Si or Si doped with a near constant As concentration of 2×10 20/cm3. The transition to amorphous formation is quite sharp for As (around 120 °C) and quite broad for Ge implants. The different amount and kind of extended defects is probably due to an interaction of the mobile point defects, vacancies and interstitials, with As. The interaction probably increases the defects annihilation rate.
Influence of Ion-Implantation on Characteristics of Picosecond Photoconductive Switches
Authors: Knudsen John F. , Bowman Robert C. , Smith Duane D. , Moss Steven C.
Published: March 2011

Ion-implantation induced amorphization has been used to modify the linearity of response of ultrafast photoconductive switches fabricated on SOS. The extent of amorphization was determined using various materials characterization techniques. TRIM-86 Monte Carlo calculations were used to model the defect densities produced by ion implantation. Linearity of response is critically dependent upon the nature of the semiconductor region under metallic contacts and the character of the response is opposite to that expected from reports in the literature.
Formation of Shallow Boron P+ Junctions Using Sb Amorphization
Authors: Ganin E. , Davari B. , Harame D. , Scilla G. , Sai-Halasz G. A.
Published: March 2011

Shallow P+ junctions have been fabricated using reverse-type dopant preamorphization by Sb. The junctions ∼100 nm in depth have leakage current below 10 nA/cm2, sheetresistance less than 200 Ω/□ and ideality factor in the range 1.01–1.03. This type of amorphization scheme provides electrical activation of B at low temperature, which is very promising for low temperature processing applications. The importance of process optimization was demonstrated. The electrical results were correlated with residual defect structure observed by cross-sectional TEM.
Silicided Shallow Junction Formation Using Ion Implantation and Thermal Annealing
Authors: Rubin Leonard M. , Herbots N. , Hoffman D. , Ma D.
Published: March 2011

The combination of arsenic and boron implantation with rapid thermal annealing (RTA) has been investigated to form shallow p-n junctions under a titanium silicide (TiSi2) metallization. The use of TiSi2 as a connection material can lead to the destruction of the junction if the kinetics of silicidation and doping are not well controlled. The purpose of this study is to better understand and control these kinetics, using far-from equilibrium processing such as ion implantation and RTA. The structures were characterized by Rutherford Backscattering Spectometry (RBS) for arsenic and silicide profiling, Secondary Ion Mass Spectometry (SIMS) for boron profiling, Scanning Electron Microscopy (SEM), and electrical sheet resistance measurements. Two procedures were investigated. Both involved the thermal reaction of Ti thin films, sputter-deposited with thicknesses ranging between 40 and 80 nm. In the first experiment, the as-deposited films were implanted with either 115 keV arsenic or 28 keV boron to form the junction, disperse the native oxide, and ion beam mix the Ti and Si. The films were then subjected to an RTA at 750°C for 15 to 60 seconds, which leads to TiSi2 formation in unimplanted films. Implantation was found to actually prevent TiSi2 formation. Ion transport calculations indicated that dopant pile-up at the interface might inhibit silicidation while higher energies and larger implant doses can more effectively ion beam mix Ti and Si. A more attractive solution consists of first forming TiSi2 from the as-deposited Ti by RTA, and then implanting to form the junction. This resulted in better control of the junction thickness. A sharp increase in the TiSi2 resistivity was found after implantation but the original value could be restored by a second RTA. This RTA also electrically activated the dopants and recrystallized the junction. The material properties of Ti/Si and TiSi2/Si under ion bombardment, RTA, doping, and conventional furnace annealing will be discussed.
Synthesis of Two-Layer TiB2-TiSi2 Structures by Boron Implantation into Titanium Film and Rapid Thermal Annealing
Authors: Tokarev V. V. , Demchenko A. I. , Ivanov A. I. , Borisenko V. E. , Zarovsky D. I.
Published: March 2011

Further progress in IC dimension reduction, increase in integration degree and speed require development and use of new current-conducting materials. This is due to the fact that existing current-conducting systems based on aluminium are low temperature, characterized by low electromi gration stability and require use of complex barrier layersi[l]. Polycide currentconducting materials have quite high resistance, interact with aluminium and are sensitive to the formation conditions. From this point of view, borides and titanium borides in particular are very promising for making current-conducting systems since they are very much characterized by good barrier properties, high conductance, properties and electromigration stability [2].
Plasma-Activated Ion Beam Reactive Sputtering of NbN Thin Films
Authors: Lichtenwalner D. J. , Anderson Alfredo C. , Rudman D. A.
Published: March 2011

In order to better study and control the processes occurring in a reactive sputtering situation, a unique deposition method has been used in which the Ar-ion-beam sputtering of an elemental Nb target is combined with an auxiliary Ar/N2 plasma at the substrate. The ion source allows independent control of the sputtering parameters (ion flux, energy). The magnetically enhanced triode plasma provides a source of ionized and excited nitrogen at the film surface, and allows independent control of the substrate plasma parameters. A conductancelimiting enclosure surrounds the substrate, resulting in a pressure differential of nearly an order of magnitude between the substrate and target regions. This enables us to separate the substrate and target reaction regimes at low nitrogen flows. NbN has been investigated because of its technological importance and the fact that it is representative of transition metal nitrides.

With the substrate plasma off and N2 provided at the substrate, the cubic superconducting NbN (δ phase) is produced even at low N2 flows, when the target is in the unreacted, metallic state. Upon increasing the N2 flow, the nitrogen content of the films abruptly increases as the target reaction proceeds. The addition of the substrate plasma results in the nonsuperconducting hexagonal δ' phase, which to our knowledge has not previously been produced as a singlephase thin film. The electrical properties of the δ' phase are reported.
About Some Peculiarities in Defect Appearence in Elemental and III–V Compound Semiconducting Materials
Authors: Kalitzova Maria G. , Pashov N. K. , Vitali G. , Rossi M.
Published: March 2011

High Resolution Transmission Electron Microscopy (HRTEM) has been used to obtain direct Information on the structure of damage clusters and in-depth radiation damage distribution in ion-implanted Ge and GaAs with Te+ and Si+ respectively, at doses far below the amorphization threshold. The observed changes in damage contrast in Te+ implanted Ge emphasize the existence of well defined separation between vacancies and interstitials in the lattice damage clusters. For GaAs an integrated “grey zone” was found as a typical effect of Si+ implantation.
On Energy and Dose Effects During Ion-Assisted Epitaxial Growth of InAs on Si(100)
Authors: Choi C.-H. , Barnett S. A.
Published: March 2011

Epitaxial InAs films have been grown on Si(100) substrates using triode ion-assisted deposition (TRIAD). The ratio r of the impinging Ar ion flux J to the deposited InAs flux was varied from 2.5 to 8.5 for Ar ion energies E from 5 to 55 eV. The growth temperature T was 350°C while the growth rate R was fixed at 0.6 μm/h. Two types of experiments were carried out. First, in order to investigate ion damage effects, X-ray diffraction rocking curve full-widths at half-maximum (FWHM) were measured as a function of E and r. In these experiments, the first 50 nm of InAs was always grown under the same conditions, r = 5 and E = 25 eV, in order to eliminate possible complicating effects caused by ion irradiation during InAs nucleation on Si, followed by 550 nm of growth at different E and r values. FWHM values increased with increasing E and r from 2800 arcsec, a value limited by defects arising from the 11% mismatch between InAs and Si, to 8900 arcsec as a result of ion damage. The FWHM value was found to be dependent on the total number of atomic displacements due to ion irradiation, estimated using a modified Kinchin-Pease expression. In the second set of experiments, E during the first 50 nm of growth was varied while ion irradiation damage in the remaining 5500 nm was minimized. Increasing E from 15 to 40 eV resulted in a decrease in the FWHM from 5500 to 2600 arcsec, followed by a gradual increase when E was increased above 40 eV. Ion irradiation at the onset of film growth thus reduced the propagation of defects from the InAs/Si interface into the film.
Ion Implantation of Boron in Diamond
Authors: Sandhu G. S. , Swanson M. L. , Chu W. K.
Published: March 2011

It has been a challenge to inject dopant atoms onto diamond lattice sites by ion implantation, because of the complications of ion damage and defect clustering during annealing. We re-investigated this topic by implanting boron ions into an insulating natural diamond ( type II-A ) which was predamaged by carbon ion implantation. Both of the implantations were performed at liquid nitrogen temperature. The amount of pre-damage was adjusted to produce enough vacancies and interstitials in diamond to promote boron substitutionality during subsequent annealing. Samples were characterized by optical absorption and electrical measurements. It was found that optical absorption of the implanted samples strongly depends on the post implant annealing sequence. The activation energies obtained from electrical measurements match very closely to those due to boron atoms in natural p-type diamonds. Photoconductivity measurements showed that the fraction of remaining electrically active radiation defects in the implanted and annealed samples depends on the relative fluences of boron and carbon.
B(1−x)Nx Alloy Films Prepared by Ion Beam Assisted Deposition
Authors: Carosella C. A. , Hubler G. K. , Van Vechten D. , Donovan E. P.
Published: March 2011

We have produced alloy films of B(1−x)Nx (x:0 to 0.5) via ion beam assisted deposition (IBAD). Rutherford backscattering spectroscopy (RBS) measurements show that the stoichiometric films are achieved with a nitrogen to boron atom arrival rate of N/B = 2.55. The film N/B ratio for all measured compositions is fit with a model that predicts that the nitrogen sticking coefficient is 0.36. Measurements of B(1−x)Nx film thicknesses with a profilometer confirm the value of this sticking coefficient. The BN film is transparent and has an refractive index that varies between 1.90 and 1.77 in the range 400 nm to 3100 nm. The refractive index data can be fit with the Sellmeier equation. Films 500 run thick with N/B less than 0.6 appear metallic; the index decreases linearly with increasing nitrogen content. The films have two broad absorption peaks, centered at 750 cm−1 and 1370 cm−1 that correspond to BN vibrations. The characteristics of the bands suggest that the films are amorphous or a microcrystalline hexagonal phase. The Knoop microhardness of the films generally decrease with increasing N content. Stoichiometric films have a microhardness of Hk = 20 GPa, measured with a 25 gm load.
A new Apparatus for Dynamical Ion Beam Mixing
Authors: Jaulin M. , Laplanche G. , Delafond J. , Pimbert-Michaux S.
Published: March 2011

A new apparatus for dynamical ion beam mixing has been developed in our laboratory. The system is based on deposition by ion beam sputtering concurrently with ion beam implantation. It operates under a vacuum of 10−5 Pa before deposition and 10−3 Pa during deposition.
Growth Mechanism of Direct Writing of Silicon in AR+ Laser CVD
Authors: Nagahori Takeshi , Matsumoto Satoru
Published: March 2011

Silicon lines are directly written using argon ion laser CVD. The thickness profile of the line has a Gaussian-like shape. The thickness profile is calculated with the model based on Arrhenius behavior. A good agreement is obtained.

The effective exposure time is used to analyze the direct writing process. Using it, the average growth rate is estimated to be about 100 times faster than that of conventional large area CVD with the activation energy of 2.4± 0.4eV.
Laser Photochemical Vapour Deposition of Epitaxial Ge Films on GaAs from GeH4 Using NH3 as a Sensitiser
Authors: Kiely C.J. , Jones C. , Tavitian V. , Eden J.G.
Published: March 2011

The viability of ammonia as a sensitiser for the epitaxial growth of Ge on GaAs by laser photochemical vapour deposition (LPVD) has been investigated. Specifically NH3/GeH4/He (0.8/5/95 sccm, 5.5 Torr total pressure) mixtures have been irradiated by a 193nm ArF excimer laser in parallel geometry for substrate temperatures, Ts<400°C. As evidenced by a dramatic acceleration in Ge film growth rate, the NH3 efficiently couples the laser radiation to the GeH4 precursor molecule. The microstructures of LPVD Ge films grown with and without NH3 have been examined by TEM, and the epitaxial nature of both types of films has been verified, although some subtle differences are noted. Chemical analysis of the deposited films has been carried out using Auger spectroscopy, X-ray photoelectron spectroscopy and secondary ion mass spectroscopy. Our results show that there is little or no nitrogen incorporation into the Ge films grown in the presence of NH3, and that hydrogen contamination in our films is minimal. The beneficial effect of NH3 on the growth rate of LPVD Ge films is attributed to the photolytic production of hydrogen atoms which efficiently decompose GeH4 by hydrogen abstraction collisions.
UV Enhancement of Surface Catalytic Polymerization of Ethylene
Authors: Purohit Parul Vora , Rothschild Mordechai , Ehrlich Daniel J.
Published: March 2011

The polymerization of ethylene on surfaces sequentially dosed with TiC14 and trimethylaluminum was studied by Fourier transform infrared spectroscopy. The polymer film was observed in situ as a function of time and under the influence of 254-nm cw radiation. The rate of polymerization and the saturation thickness of the polyethylene are strongly dependent on the order of dosing and the partial pressures of the reactants that form the catalyst. UV enhancement of polymerization was demonstrated to occur through two separate photochemical channels: gas-phase photolysis of the reactants and solid-phase chemical transformation of a noncatalytic thin film.
Photodissociation of Chlorine on a Cooled Silicon Wafer
Authors: Kawasaki Masahiro , Sato Hiroyasu , Nishi Nobuyuki
Published: March 2011

Laser irradiation at 193 nm of multilayered Cl2 on an Si wafer cooled to 100 K leads to both photodissociation of Cl2 and formation of photoetching products.
Laser Induced Wet-Chemical Etching of Mn-Zn Ferrite in H3PO4
Authors: Lu Yong Feng , Takai Mikio , Nagatomo Syohei , Namba Susumu
Published: March 2011

Maskless etching of single crystalline Mn-Zn ferrite in an H3PO4 aqueous solution by Ar+ laser irradiation has been investigated to obtain high etching rates and aspect-ratios of etched grooves. The etching processes have been found to be photochemical in a low laser power region and thermochemical in a high laser power region. High etching rates of up to 340 pm/s and an aspect-ratio of 50 for slab structures have been achieved. Periodic ripple structures have been observed under specific etching conditions due to the local surface melting.
Ultraviolet Laser Ablation of a Silicon Wafer
Authors: Kawasaki Masahiro , Sato Hiroyasu , Inoue Gen
Published: March 2011

Pulsed laser irradiation at 248 nm can ablate Si atoms from an Si wafer. The mechanism of this photoablation has been examined by laser-induced fluorescence analysis of the Si products. The Si atoms are measured to leave the wafer surface with averaged translational energy of 2.5 kcal/mol. The distribution of translational energy is well described by the theoretical model for non-cascade ablation processes.
Excimer Laser Thin Metallic Film Patterning on Polyvinyledene Difluoridea)
Authors: Gauthier Michel , Bourret Richard , Jen Cheng-Kuei , Adler Eric L
Published: March 2011

Tactile sensors and ultrasonic transducers based on the piezoelectric properties of polyvinyledene difluoride, PVF2, usually take the form of thin 10 - 110 μm polymer films coated on one or both sides with a metallic film. Electrode patterns are usually fabricated by photolithography that requires a 90 °C baking process which may harm the piezoelectric properties of the PVF2 film. We have developed an alternate method, based on direct patterning with a XeCl laser, yielding complex patterns of lines as narrow as 20 μm which are better than those fabricated by photolithography. The metallic film is ablated on both sides of the polymer while maintaining the intrinsic properties of the PVF2. The ablation mechanism is investigated using transmission optical, scanning electron, and scanning acoustic microscope images. The performance of an ultrasonic transducer fabricated with this technique is described.
High Current Density Electron Beam Induced Desorption
Authors: Berger S.D. , Macaulay J.M. , Brown L.M. , Allen R.M.
Published: March 2011

High current density electron beam irradiation with a small probe can lead to the production of holes in a variety of inorganic materials. We review some of the experimental observations of the hole formation process and compare these to the predictions of a simple model.
Formation of a Ni3O4 Spinel Phase on the Surface of NiO During Electron Irradiation
Authors: Buckett Mary I. , Marks L. D.
Published: March 2011

Structural changes occurring at the surface of NiO during electron irradiation were examined in-situ with a variable voltage high resolution electron microscope. The interaction of the specimen with the electron beam was found to be highly dependent on the state of the surface prior to irradiation. It was observed that by varying the sample preparation conditions, the Ni on the surface of NiO could either be oxidized to Ni304 spinel phase or reduced to islands of metallic Ni. The formation of the Ni3O4 spinel phase is in agreement with previous surface science studies, where chemical shift information identified the presence of Ni3+ species at the surface. This has previously been interpreted as the formation of Ni203
RF Plasma CVD Using Hollow Cathode Discharge
Authors: Araki Shin , Kamaji Hideki , Norimoto Kazuo
Published: March 2011

We have made a-Si photoreceptors at low pressure to prevent the formation of SimHn powders and by separating the growing surface from the high density plasma. A new plasma CVD method using a hollow-cathode discharge, where the discharge electrode is the cathode, is described. There is a hollow region in the discharge electrode. Hollow-cathode discharge enables a high density plasma to form at low pressure. The gas is decomposed in the hollow cathode preventing plasma damage to the film. This method allows us to achieve a high deposition rate (10 µm/h) and good quality films for photoreceptors.
Selective-Area Laser-Assisted Processing for Microelectronic Multi-Chip Interconnect Applications
Authors: Miracky Robert F.
Published: March 2011

Laser direct-write processes are attractive complements to traditional methods of fabricating microelectronic circuitry. This paper is a summary of our work in applying such processes to high-density inter-chip interconnection modules, such as those using copper conductors on polyimide dielectric layers. We begin by discussing the requirements which laser processes must satisfy in order to be useful in this application. An analytical model of laser heating is then described, which aids in understanding the thermal problem of absorption of visible-wavelength laser light by polyimide. Calculations using this model are consistent with experimental observations. Finally, we focus on one laser processing technique: laser chemical vapor deposition. We describe a new process for laser chemical vapor deposition of tungsten on polyimide, which enables the formation of low resistance contacts (≈ 0.1 Ω) between the deposited tungsten films and pre-patterned nickel-coated copper conductors. Lines approximately 30 /m wide and 34 µm thick were deposited at a scan rate of 93 µm/s. From four-point resistance measurements of different lengths of deposited films, the tungsten film resistivity is estimated to be two to three times the bulk value.
Flashlamp-Pumped Dye and Excimer Laser Planarization of Thin Metal Films
Authors: Marella Paul F. , Tuckerman David B. , Pease R. Fabian
Published: March 2011

The fundamental differences between excimer (≈ 30 ns pulse duration) and flashlamp-pumped dye (≈ 500 ns pulse duration) laser planarization are examined for 1.5-2 µm thick gold films over SiO2 layers. Test structures containing bar patterns (square waves) of 5000 Å peak-to-trough amplitude with spatial periods ranging from 10 µm to 100 µm were prepared and laser-irradiated. A linear model is presented which describes the time-evolution of the film's surface topography when melted with a dye laser pulse. Excimer laser planarization is found to be susceptible to evaporative recoil effects which may cause undesired pattern amplification.
Single & Multiple Pulse Ablation of Polymeric and High Density Materials with Excimer Laser Radiation at 193NM and 248NM
Authors: Elliott David J. , Piwczyk Ernhard P. , Elliott David J. , Piwczyk Bernhard P.
Published: March 2011

The evolution of the excimer laser from a research tool in the 1970's to the industrial models of the 1980's has opened up numerous applications in semiconductor manufacturing, materials processing, and biological and medical research. Present production-capable, computercontrolled excimer systems with handling equipment enabling efficient automation can now operate for up to 50 million shots before undergoing scheduled maintenance, with fluences remaining within ±10% in most cases. Thus, although many uses for the excimer laser are still researchoriented, production applications are rapidly emerging.
Lif-Diagnostics of Cr During Laser-Induced Deposition from Cr(CO)6
Authors: Rieger D. , Rager B. , Bachmann F.
Published: March 2011

The spatial and temporal distribution of Cr* in a laser-CVD arrangement has been studied by laser-induced fluorescence (LIF). Low excited Cr*(a5S2) atoms are produced by dissociation of Cr(CO)6 by a KrF laser ( λ = 248 nm) via two photon absorption. An observed disappearance of Cr* after photolysis is due to reaction with photofragments, quenching via collision relaxation and deposition. The diffusion constants for Cr* in He/Cr(CO)x mixtures could be determined. The Cr* density in the vicinity of a sample drops sharply by heating the sample. The decrease is due to thermal decomposition of Cr(CO)6 with an activation energy of 0.11 eV.
Micro-Indentation and Micro-Scratch Tests on Sub-Micron Carbon Films
Authors: Wu T. W. , Burn R. A. , Chen M. M. , Alexopoulos P. S.
Published: March 2011

Micro-indentation and micro-scratch techniques were used to characterize the hardness and the adhesion strength of 0.11 μm thick sputtered carbon f-ilms on Silicon substrates. Hardness depth profiles and critical loads were measured using a microindenter under indentation and scratch testing modes, respectively. The carbon film with 6 mtorr argon sputtering pressure shows better practical adhesion (or higher critical load) and slightly higher hardness. The indentation fracture phenomenon observed on the 30 mtorr film is closely related to its poor adhesion. The failure mechanism will also be discussed.
Hardness and Elastic Modulus Measurements in CdTe and ZnTe Thin Film and Bulk Samples and ZnTe-CdTe Superlattices
Authors: Farthing L. J. , Weihs T. P. , Kisker D. W. , Krajewski J. J. , Tang M. F. , Stevenson D. A.
Published: March 2011

Hardness and modulus values of bulk and epilayer ZnTe and CdTe samples and of ZnTe-CdTe superlattices are reported. Both hardness and Young's modulus values increase with increasing ZnTe content in the ZnCdTe samples. Alloying effects and strains in the superlattice structure are proposed to explain the strengthening.
Mechanical Properties of Nanometre Volumes of Material: use of the Elastic Response of Small Area Indentations
Authors: Pethica J. B. , Oliver W. C.
Published: March 2011

A new, differential method for determining the stiffness of a sub-micron indentation contact area is presented. This allows measurement of elastic modulus as well as plastic hardness, continuously during a single indentation, and without the need for discrete unloading cycles. Some of the new experiments that become possible with this technique, especially at the nanometre scale, are described. We show quantitatively that electropolished tungsten reproducibly exhibits the ideal theoretical lattice strength at small indentation loads.
Mechanics of Elastic Dislocations in Strained Layer Structures
Authors: Freund L. B. , Bower A. , Ramirez J. C.
Published: March 2011

Application of the elastic continuum theory of dislocations to modeling of phenomena associated with elastic strain relaxation in strained layer epitaxial heterostructures is discussed. The concept of critical thickness for onset of strain relaxation in a strained epitaxial layer is first reviewed, and some extensions to periodic arrays of dislocations and to multiple layers are described. Then, two issues are addressed that arise when the assumptions underlying the critical thickness concept are not met. One issue concerns the nucleation of dislocations at the growth surface of an epitaxial film, particularly the influence of surface irregularities on the activation energy for surface nucleation. A second issue concerns the kinetics of glide of a threading dislocation as it lays down an interface misfit dislocation when the layer thickness exceeds the critical thickness. A generalized driving force for the glide process is defined, and a relationship between this force and the glide speed is proposed.
Strain Relief Mechanisms and Nature of Misfit Dislocations in GaAs/Si Heterostructures
Authors: Sharan S. , Narayan J. , Salerno J. P. , Fan J. C. C.
Published: March 2011

The nucleation and glide of misfit dislocations in GaAs/Si system is investigated using transmission electron microscopy. GaAs epilayers of different thicknesses were examined by electron microscopy (plan and cross-section) and the elastic strain remaining in the film has been related to the average spacing of the misfit dislocations at the interface. A model is developed based on minimum energy considerations to determine the strain-thickness relationship. The theoretical predictions of strain relaxation are compared with experimental observations using high resolution electron microscopy.
Effect of Highly Strained Superlattices on the Threading Dislocation Behavior in GaAs Grown on Silicon
Authors: El-Masry N. A. , Tarn J. C. L. , Karam N. H. , Bedair S. M.
Published: March 2011

GaAs films grown on silicon substrates suffer from a high density of threading dislocations. One technique to reduce these dislocations is the use of strained layered superlattices (SLS) InGaAs-GaAsP as buffer. We found that the effectiveness and interactions of the SLS with the threading dislocations strongly depend on the dislocation type and the strain field of the superlattices. Because of the high dislocation density in GaAs/Si, the SLS acts as a medium for dislocation interactions and annihilations. Highly strained SLS (∼ 2%) is required to bend the dislocations and keep them bent at the strained interfaces. We found that the combination between annealing and a highly strained superlattice coupled with selective epitaxy is an effective approach to reduce the threading dislocations in GaAs grown on Si. Transmission electron microscopy is used to study these effects.
Critical Thickness for Three-Dimensional Epitaxial Island Growth
Authors: Jagannadham K. , Narayan J.
Published: March 2011

The generation of misfit dislocation loops in three-dimensional epitaxial islands grown on thick substrates is analyzed. The coherent strain in the island is described by virtual interfacial dislocation loops situated in the interface. The traction free surface boundary conditions are satisfied by the surface dislocation loops situated on the surface of the island. A misfit dislocation loop is formed and the changes in the energy of the configuration used to determine if the total energy is lowered. The numerical analysis is carried out forhemispherical islands of GaAs grown on (100) silicon with a misfit dislocation of Burgers vector 3.84 Å. It has been found energetically favorable to nucleate a misfit dislocation loop at a distance of 3 å from the interface when the radius of the hemispherical island is equal to or greater than 40 å. In addition, a misfit dislocation loop could be nucleated at a larger distance from the interface when the size of the island is larger.
X-Ray Diffraction Studies of Annealed SiGe/Si SLS
Authors: Lowe Walter P. , Macharrie R. A. , Bean J. C.
Published: March 2011

We have done x-ray diffraction to study the affect of annealing on a SiGe/Si strained-layer superlattice (SLS). The post anneal spatial distribution of the Ge and Si atoms within the alloy layer is of particular interest. X-ray data taken from an annealed sample along the superlattice direction (100) show two sharp and well separated superlattice envelope functions. In contrast to the unannealed sample, and what would be a typical scattering spectra for a superlattice, the envelopes bisect the position of the unannealed sample's envelope function. The position of the envelope function is related to the tetragonal distortion εT in the SiGe alloy layers. The two separate envelopes (α and β) show that the SiGe alloy (100) planes have divided themselves into two groups with different interplanar spacings after the anneal. Each group with a tetragonal distortion such that and where εT is the tetragonal distortion in the unannealed sample. This is strong evidence for coherent phase separation perpendicular to the growth direction, along the SiGe alloy layer. In another investigation a search of reciprocal space for the 2 × 2 {… SiSiGeGe…} (111) chemically ordered state showed no evidence for the existence of such an ordered state.
The Cracking and Decohesion of Thin Brittle Films
Authors: Hu Mu-San
Published: March 2011

Film cracking and decohesion are two typical failure modes observed in thin coatings. In this investigation, failures were initiated in brittle Cr films deposited on both ductile and brittle substrates to study these phenomena. Fracture mechanics models were proposed to interpret the experimental observations. Excellent agreement between theory and experiment has been demonstrated.
Tailored Nicrostructures to Control Interfacial Toughness
Authors: Oh T. S. , Cannon R. N. , Ritichie R. O.
Published: March 2011

Failure of ceramic-metal interfaces in response to residual or applied stress is frequently effectively brittle owing to the propensity for interfacial cracking caused by weaker than average chemical bonds and elastic or plastic discontinuities at the interface. Stronger atomic bonding derived from improved interfacial chemistry can enhance fracture resistance to a degree which may be limited by diversion of the crack into the brittle ceramic.

Alternatively, methods under study promote interfacial fracture toughness in glass-Cu bonds via near-interfacial microstructures that encourage greater energy dissipation in a region near the interface fracture. Particular success has obtained from microvoid toughening wherein placement of controlled arrays of microcrack-like-voids in the ductile metal, suitably near the interface, can markedly enhance interfacial fracture energy, e.g. by as much as two orders of magnitude and to much greater toughnesses than for glass. The toughness develops with extension of the crack owing to formation of a bridging zone behind the crack wherein the crack flanks are spanned by ligaments of plastically deforming metal film.
Simple Models for Surface Cracking
Authors: Meakin Paul
Published: March 2011

A simple model for crack growth in thin films deposited onto a substrate has been developed. This model results in the generation of cracking patterns which have a remarkably realistic appearance. In the simulations a slow crack initiation period is followed by a period of rapid crack growth in which quite linear cracks are formed. Later on the crack growth process becomes slower and less regular as the cracking process relieves much of the stress in the surface layer. In this model pre-existing defects have a large effect on the crack growth kinetics and morphology.
Adherence of Diamond Films Produced by Microwave Plasma Deposition on Sialon Tool Inserts
Authors: McCune Robert C. , Hoffman D. W. , Whalen T. J. , McHugh C. O.
Published: March 2011

The adherence of diamond films produced by microwave-enhanced chemical vapor deposition (CVD) on SiAlON tool inserts was assessed by scratch, indentation and machining tests on aluminum alloys. While the films are nominally adherent during handling and mild cutting operations, the measured adherence values are appreciably lower than values associated with conventional CVD coatings on cobalt-tungsten carbide cutting inserts. An indentation type adhesion test using polished substrates was found to yield reproducible behavior for interfacial crack extension at loads ranging from 15 to 150 kg. The “critical load” in scratch testing was found to be less than 10 N.
Long-Range Coherency Strain and Tilted Ipitaxy in Ag-Fe-Ag Sandwich Structures on Gaas(001) Substrates
Authors: Farrow R. F. C. , Speriosu V. S. , Parkin S. S. P. , Chien C. , Bravman J. C. , Marks R. F. , Kirchner P. D. , Prinz G. A. , Jonker B. T.
Published: March 2011

We find that epitaxial Fe films sandwiched between epitaxial Ag films grown on GaAs (001) substrates possess residual coherency strain at a thickness of 2000Å. The [001] directions of the Fe and Ag films are tilted with respect to the GaAs [001] axis. The tilts are coplanar with the tilt of the substrate surface normal to the [001] axis of GaAs and are qualitatively consistent with a recently proposed modol for tilted epitaxy.
Relationship Between Interfacial Strain and the Elastic Response of Multilayer Metal Film
Authors: Clemens Bruce M. , Eesley Gary L.
Published: March 2011

We have used x-ray diffraction and picosecond transient piezoreflectance to investigate the structural and elastic properties of three distinct multilayer systems: Mo/Ni, Pt/Ni and Ti/Ni. We demonstrate that the commonly observed lattice expansion perpendicular to the film plane is not a bulk effect, but is localized at the interface between the contacting metals. Incorporating the measured interfacial expansion into a universal binding relation, we show that the measured elastic softening versus compositional repeat distance can result from the interfacial strain.
Thin Film Stresses in TiW/AlCuSi/TiW Sandwich Structures
Authors: Wang Iton
Published: March 2011

A highly reliable metallization for high current bipolar integrated circuits was developed with the aid of thin film stress analysis to optimize the process. The final structure was a sandwich layer of TiW and AlCuSi alloy. Film stresses were measured for individual TiW layers as well as for the sandwich layers of TiW/AlCuSi/TiW. In this paper, it will be shown how sputter deposition pressure can drastically affect film stress. For individual TiW layers, the film stress can be varied between compressive and highly tensile by adjusting the Argon pressure. Meanwhile, the AlCuSi layers were always tensile under the normal range of sputtering pressures. By controlling the individual film stresses, a sandwich layer can be designed so that the overall structure has a very low average stress. This work will also show how a TiW capping layer has a major effect on the final average stress of the sandwich structure.
Control and Variation of Stress in Pecvd SiNx Films on InP
Authors: Lopata J. , Dautremont-Smith W. C. , Lee J. W.
Published: March 2011

Stress in plasma enhanced chemical vapor deposited (PECVD) SiNx films on InP has been evaluated as a function of source gases (NH3 /SiH4 or N2/SiH4) and plasma operating frequency (high, » 1 MHz or low, « 1 MHz). All films were deposited at 300°C in the same parallel-plate, radial flow plasma reactor. Levels of stress in PECVD SiNx on InP within a continuous range from moderately high tensile (∼ 5 × 109 dyne cm−2) to very high compressive (2 × 1010 dyne cm−2 ) were obtained from appropriate choices of deposition parameters. Deposition from NH3/SiH4 at high frequency produces tensile stress, of magnitude increasing with NH3/SiH4 flow ratio. Deposition from N2/SiH4 at high frequency produces zero to low compressive stress. At low frequency compressive stress is always produced; for N2/SiH4 increasing the gas flow ratio from 25:1 to 500:1 reduces the compressive stress from 1.8 X 1010 to 7 × 108 dyne cm−2. The ability to vary the stress in a dielectric film of approximately constant chemical composition over such a broad range is beneficial for assessing the effects of stress on device performance.
Interfacial Fracture Mechanics
Authors: Hutchinson John W.
Published: March 2011

The mechanics of interface cracks has recently been clarified (e.g., [1]) and a number of efforts are underway to develop a mechanics of interface fracture with applications to composite materials, thin film/substrate systems, and coatings. An intrinsic feature of interfacial fracture is its mixed mode character wherein both shear and normal stresses act on the interface directly ahead of the crack. Depending on geometry and loading, the mixture of modes can range from purely normal stresses (mode I) to purely shear stresses (mode II). Toughness of an interface is characterized by critical combinations of mode I and mode II stress intensity factors (i.e., a locus of critical combinations) rather than just the single critical mode I stress intensity factor in the fracture of homogeneous materials. Equivalently, the critical energy release rate depends on the mode combination for interfacial fracture. Solutions are now available to the following problems: an interface crack in a layered structure where a very thin layer is sandwiched between two thick layers of different material [2], an interface crack between two layers of arbitrary thickness subject to arbitrary combinations of bending and stretching loads [3], and a crack in a substrate paralleling an interface between a thin film and the substrate driven by a variety of loadings including residual tension in the film [4]. These solutions can be used to analyze specimens for determining interfacial toughness and for predicting cracking in thin film or layered structures.
Silicon Nitride Fibers Using Micro Fabrication Methods
Authors: Koskinen J. , Johnson H. H.
Published: March 2011

Amorphous LPCVD and PECVD Si3N4films have been patterned into fibers of various shapes using integrated circuit methods. A tensile test apparatus was developed which allows a simultaneous testing of up to 20 fibers. The average tensile strength of LPCVD Si3N4fibers with a 30 μm gauge section was 7.0 ± 0.4 GPa. The corresponding value for PECVD Si3N4was 2.4 ± 0.2 GPa. The following properties of the materials were measured: atomic composition (RBS, FRES), density, refractive index, internal stress, elastic modulus and micro hardness. A Weibull analysis of the tensile strength values was performed.
Mechanical Testing of Thin Films
Authors: Rosenmayer C. T. , Brotzen F. R. , Gale R. J.
Published: March 2011

Metal films used as conductors in integrated circuits must be able to withstand stresses created during their deposition, caused by mismatches in thermal expansion coefficients and by bending which occurs during manufacture and installation. These stresses may be biaxial or uniaxial in nature. This paper discusses testing techniques and gives examples of results of mechanical testing of thin metallic films of aluminum, aluminum-copper(2%), copper, and tungsten in uniaxial and biaxial tension. The film specimens were deposited on and removed from production silicon wafers in order to simulate as much as possible actual device conditions. Basic considerations for the comparison of the two testing methods are also presented.