bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Characterization of Laser-Annealed Sputtered Poly-Si Films for High Mobility Tfts
Authors: Okamoto Akio , Shirai Seiiti , Suyama Shiro , Serikawa Tadashi
Published: March 2011

A high mobility of 390 cm2/Vs was successfully obtained for sputtered films, compared with 100 cm2/Vs for CVD films. Then, structural characterization of laser-annealed sputtered silicon films were performed, and compared with that of CVD films. TEM observations show a structural difference between the two film types. In sputtered films, many fine grain-like regions which have slightly different crystal orientation from surrounding regions are observed. On the other hand, in the CVD films, defects are widely spread over the film. X-ray diffraction, Raman scattering, and SIMS yield almost the same results in both films. The above-mentioned structural difference is thought to be essential to obtain high mobility.
Microstructure of BaTiO3 Thin Films Grown by Reduced-Pressure CVD
Authors: Van Buskirk Peter C. , Gardiner Robin , Kirlin Peter S
Published: March 2011

Polcrystalline BaTiO3 films have been grown on NdGaO3 [100], SrTiO3 [100] and Si [100] substrates by reduced pressure CVD. The substrate temperature was 1000°C and the total pressure during growth was 4 torr. X-ray diffraction measurements indicate highly textured films on the NdGa03 substrate. The orientation was predominantly [100], accompanied by small quantities of various TiO crystalline phases.
Microstructural Changes During Processing of Laser-Deposited BaTiO3 and Pzt Thin Films
Authors: Cook L. P. , Vaudin M. D. , Schenck P. K. , Wong-Ng W. , Chiang C. K. , Brody P. S.
Published: March 2011

Thin films of BaTiO3 and PZT (lead zirconate titanate, 47%PbTiO3, 53%PbZrO3) have been produced by laser irradiation of the appropriate ceramic targets and deposition of the ejected and vaporized material on planar substrates. The microstructural changes during thermal processing of these films have been studied by scanning electron microscopy/energy dispersive x-ray spectrometry (SEM/EDX), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), x-ray diffraction (XRD), and by measurement of electrical properties. Films have been deposited using both Nd/YAG and excimer lasers and on unheated as well as heated substrates. Excimer films are considerably smoother than the Nd/YAG films, and the uniformity of the as-deposited microstructures is promoted by substrate heating. However, ferroelectric hysteresis loops were only observed for the considerably less smooth Nd/YAG PZT films; thermal treatment did little to improve the smoothness of these films. An excimer BaTiO3 film deposited on a heated substrate showed crystallographic alignment and had a dielectric constant of −100. Efforts are underway to combine the best features of films produced by both methods.
The Effects of Substrate Conditions on the Microstructural Evolution of Thin Diamond-Like Films
Authors: Cuomo J. J. , Bruley J. , Doyle J. P. , Pappas D. L. , Saenger K. L. , Liu J. C. , Batson P. E.
Published: March 2011

We report on a study of hard amorphous carbon thin films prepared by condensing streams of energetic carbon species, onto a range of substrates maintained at different temperatures. The carbon vapor is generated either by ion sputtering, laser ablation or e-beam evaporation. Spatially resolved electron-energy-loss spectra reveal variations in the films′ microstructure brought about by altering the deposition conditions. We estimate that the density of the different films varies between 2.0 and 3.26 g/cm3. We observe an evolution towards denser films upon increasing incident beam energy, reducing substrate temperature, and increasing substrate thermal conductivity. Low density films contain a predominance of trigonally bonded sp2-hybridized carbon (i.e graphitic carbon) and the highest density films contain a high fraction (∽ 80%) of tetr-ahedral sp3-bonded carbon (i.e. diamond-like).
The Growth and Characterisation of Ir Silicide Films on (111)Si
Authors: Lawn M.A. , Elliman R.G. , Ridgway M.C. , Leckey R. , Riley J.D.
Published: March 2011

A study of the growth of thin Ir silicide films on (111)Si substrates has been undertaken. Thin (2.0nm) ir films deposited onto Si substrates under ultra-high vacuum conditions have been observed to display remarkable film continuity and fine grain structure (lnm). In situ annealing at 1000°C resulted in the formation of large regions (>10µm) of epitaxial IrSi3 islands (∼1µm) with identical epitaxial orientations. By means of annealing an as-deposited (2.0nm) Ir film stepwise to 1000°C within a transmission electron microscope the evolution of Ir silicide phases and morphologies were observed. The epitaxial growth of the semiconducting IrSi1.75 phase is reported along with the formation of Ir silicide islands at temperatures between 700°C and 800°C.
Effects Of Ar+ Ion Bombardment on the Nucleation and Growth of Ag Thin Films
Authors: Cotell C.M. , Sprague J.A. , Gossett C.R.
Published: March 2011

Thin films of Ag were grown on amorphous C and <111= Si substrates with simultaneous Ar+ bombardment at energies ranging from 50–40,000 eV. For deposition of Ag on amorphous C, ion beam bombardment induced no changes in film nucleation behavior relative to evaporation (henceforth referred to as physical vapor deposition, PVD). Film growth was affected at the highest energy (40 keV); the grain size of the Ag films was increased by a factor of three. Rutherford Backscattering (RBS) measurements on Ag films on <111=Si bombarded with Ar+ at 1.5 keV showed that the Ag sputtering yield at film thicknesses <1.5 nm was less than for bulk Ag, in agreement with TRIM calculations. At 40 keV there was evidence for an additional effect of the ion beam due to recoil implantation or ion mixing. Electron diffraction from Ag fdms grown on <111= Si substrates with simultaneous Ar+ bombardment at either 1.5 keV or 40 keV showed evidence for only the expected phases: single crystal Si, polycrystalline Ag, and an amorphous phase that likely resulted from ion damage to the substrate.
Structure Determination of the Nisi2(111) Surface Using Medium Energy Ion Scattering with Monolayer Resolution
Authors: Vrijmoeth J. , Zagwijn P.M. , Frenken J.W.M. , van der Veen J.F.
Published: March 2011

The surface structure of epitaxial NiSi2 films grown on Si (111) has been determined using a new method. The backscattering signals from subsequent Ni layers in the NiSi2 (111) surface are resolved.

The topology of the NiSi2 (111) surface is concluded to be bulklike, i.e., it is terminated by a Si – Ni – Si triple layer.
GaAs(100) Surface Modifications at Elevated Temperatures, Studied By In-Situ Spectroscopic Ellipsometry
Authors: Yao Huade , Snyder Paul G , Woollam John A
Published: March 2011

Spectroscopic ellipsometric (SE) measurements of GaAs (100) were carried out in an ultrahigh vacuum (UHV) chamber, without arsenic overpressure, at temperatures ranging from room temperature (RT) to ∼610°C. Surface changes induced at elevated temperatures were monitored by in-situ spectroscopic ellipsometry. The SE data clearly displayed in real time the process of desorption of the GaAs-surface-oxide overlayer at ∼580°C. In addition, changes in the near-surface region were observed before and after the oxide desorption. The near-subsurface region (top 50–100 Å) became less optically dense after being heated to 540°C or higher. For comparison, a pre-arsenic-capped molecular-beam-epitaxy (MBE)-grown GaAs surface was also studied. After the arsenic cap was evaporated off at ∼350°C, this surface remained smooth and clean as it was heated to higher temperatures.
Microstructural Evolution of Epitaxial LiNbO3 Thin Films Derived From Metal Alkoxide Solutions
Authors: Nashimoto Keiichi , Cima Michael J. , Rhine Wendell E.
Published: March 2011

The evolution of the microstructure of sol-gel derived LiNbO3 thin films was investigated to understand the growth of epitaxial films. LiNbO3 films were prepared from a precursor solution of lithium ethoxide and niobium pentaethoxide. Prehydrolysis promoted the development of polycrys-talline LiNbO3 films, whereas nonhydrolysis produced solid-state epitaxial growth of LiNbO3 films on sapphire substrates. Although the films looked smooth after annealing at 400°C, the morphology of the films changed, depending on substrates and precursors, due to grain growth at high annealing temperature. Prehydrolysis of the alkoxides caused a decrease in the temperature at which grain growth occurred, whereas the film prepared from the nonhydrolyzed precursor on a sapphire substrate showed denser texture and contained abnormally large domains that appeared to be single phase.
Deposition of Highly Transparent and Conductive Fluorine Doped Zinc Oxide Films
Authors: Hu Jianhua , Gordon Roy G.
Published: March 2011

Zinc oxide films have been deposited from dimethyl zinc and oxygen in an atmospheric pressure laminar flow reactor at temperatures ranging from 300°C to 450°C. Highly oriented, conductive and transparent films were obtained at temperatures above 400°C by doping the films with fluorine. The crystallite sizes increase with increasing deposition temperature. From electron microprobe analysis, the doped films usually contained 0.5% to 2% fluorine atoms. Hall coefficient and resistance measurements at room temperature gave electron concentrations above 1020cm−3 and resistivities around 10−3 Ωcm. The doped films had mobilities varying from 20 to 40 cm2/V-s depending on the deposition temperature and fluorine concentration. These are the highest mobilities reported for zinc oxide films. The experimental results were then compared with those obtained from a simple resistivity network model which includes the effects of impurity and grain boundary scattering. Films with a sheet resistance of 5 Ω/square have visible absorption of about 5 to 10%. These properties are very suitable for applications as transparent electrodes for flat-panel displays and other electro-optical devices.
Growth and Characterization of Heteroepitaxial Nickel Films on Diamond Substrates
Authors: Humphreys T. P. , Jeon Hyeongtag , Nemanich R. J. , Posthill J. B. , Rudder R. A. , Malta D. P. , Hudson G. C. , Markunas R. J. , Hunn J. D. , Parikh N. R.
Published: March 2011

In the present study epitaxial Ni(001) films have been grown on natural C(001) substrates (type la and Ha) and homoepitaxial C(001) films. Two deposition techniques including electron-beam evaporation of Ni in a molecular beam epitaxy (MBE) system and evaporation of Ni from a resistively heated tungsten filament have been employed. As evidenced by scanning electron microscopy (SEM), the Ni films deposited by electron-beam evaporation were found to replicate the very fine, unidirectional scratches present on the as polished C(001) substrates. Indeed, the coverage and uniformity of the deposited films would imply a two-dimensional (2-D) growth mode. In comparison, the thermal evaporation of Ni on C(001) substrates results in a highly textured and faceted surface morphology indicative of three-dimensional (3–D) nucleation and growth. Moreover, Rutherford backscattering/channeling measurements have demonstrated that the Ni(001) films deposited by electron-beam evaporation are of superior crystalline quality. Differences in the observed microstructure and apparent growth modes of the epitaxial Ni(001) films have been attributed to the presence of oxygen incorporation in those layers deposited by thermal evaporation.
Relaxation of Capped Strained Layers Via the Formation of Microtwins
Authors: Hwang D. M. , Schwarz S. A. , Ravi T. S. , Bhat R. , Chen C. Y.
Published: March 2011

A new strain relief mechanism in epitaxial layers of lattice mismatched face-centered cubic materials is identified using transmission electron microscopy. For an embedded strained layer near its critical thickness, we find that the primary strain-relaxation channel is through the formation of microtwins. A monolayer microtwin (a stacking fault) spanning the strained layer can form when a pair of partial dislocations of the <112> /6 type with antiparallel Burgers vectors are generated inside the strained layer and glide to the opposite interfaces. A series of partial dislocations can result in a microtwin several monolayers thick. For embedded strained layers of materials with small stacking fault energy, the formation of partial dislocation pairs is an energetically-favored strain relaxation channel, as compared to the formation of perfect dislocation pairs in the conventional double-kink model. Therefore, the mechanism proposed here poses fundamental limitations for strained layer device structures.
Spontaneous Change of Growth Orientation of InGaP/GaAs Superlattices in MBE
Authors: Mahalingam K. , Nakamura Y. , Otsuka N. , Lee H. Y. , Hafich M. J. , Robinson G. Y.
Published: March 2011

The influence of growth interruption during the MBE growth of (100) In0.5Ga0.5P/GaAs superlattices is investigated by cross-sectional TEM. It is observed that for certain combinations of interruption lengths and group V fluxes, the growth orientation of the superlattice changes spontaneously from [100] to <311> direction. V-shaped grooves with {311} facets form initially in the growth plane and eventually lead to the formation of regions of {311} superlattice structures. The direction of V-shaped grooves is along the [011[ axis, which is parallel to the surface dangling bonds of the group V atoms in the unreconstructed (100) plane. The most critical stage for the spontaneous change of the growth orientation is the interruption after the growth of a GaAs layer with the P2 flux. Our observations suggest that small but stable {311} facets form at this stage and develop into well-defined {311} growth planes during the growth of the GaAs layer.
A Study of FeAl/AlAs/GaAs Interfaces Using Moiré-Fringe Contrast in a Transmission Electron Microscope
Authors: Angelo J. E. , Kuznia J.N. , Wowchak A.M. , Cohen P. I. , Gerberich W. W.
Published: March 2011

This paper describes the transmission electron microscope (TEM) investigations of the defect structure present at various FeAl/AlAs/GaAs interfaces. Although a systematic study has not yet been completed it is shown that by changing the growth temperature from 200°C to 300°C the growth morphology changes significantly. In-situ RHEED studies show the growth mode changes from layer-by-layer to island-like when the growth temperature is increased. TEM in both plan-view and cross-sectional modes is used to confirm these results. It is found that by increasing the growth temperature from 200°C to 300°C the growth mode switches from layer-by-layer (2D) with a continuous FeAl film, to island-like (3D) with significant numbers of “pin-holes”. A Moiré-fringe analysis is applied to determine the Burgers vector of the misfit dislocations. In both cases the interface between the FeAl and AlAs consists of a grid of misfit dislocations with [100] and [010] line directions whose Burgers vectors are [010] and [100] respectively.
Island Dynamics in Film Aging
Authors: Marsh S. P. , Glicksman M. E.
Published: March 2011

A theory is presented which describes the capillary-driven aging of discontinuous thin films on a substrate, where the primary transport mechanism among the domains is two-dimensional diffusion of species over the substrate. This theory employs a statistical dynamics formulation, whereby the average growth rate for each domain size class is determined relative to the critical (zero-growth) domain size. The time dependence of the critical size is determined through a global constraint on the individual fields. The effect of fractional area coverage, Aa, is accounted for through a second global constraint over the distribution of island sizes.

This theory yields a self-similar size distribution that is fairly insensitive to Aa. The critical island radius, R*, is found to increase asymptotically as the cube-root of time. The growth rate of R* increases with Aa, which results from the closer proximity of the islands and steeper concentration gradients as Aa increases.
Thickness Dependence of Epitaxial TiSi2 on Si(111).
Authors: Jeon Hyeongtag , Honeycutt J. W. , Sukow C. A. , Rozgonyi G. A. , Nemanich R. J.
Published: March 2011

The epitaxy and morphology of TiSi2 on Si(l 11) are studied as a function of Ti thickness. Titanium thicknesses of 1–2 monolayers and Ti films with thicknesses of 50Å; were examined. The titanium silicide films were formed on atomically clean Si substrates by ultrahigh vacuum (UHV) deposition of Ti followed by in situ annealing. In situ LEED and AES measurements characterized the reaction process. For room temperature deposition of less than two monolayers of Ti the LEED pattern associated with the reconstructed substrate disappeared, and the 1×1 bulk pattern also disappeared completely. Annealing at 200°C resulted in a decrease in the Ti AES signal indicating interdiffusion. For annealing up to 500°C, a series of changes in the LEED patterns were observed, which indicated that the disordered layer transformed to an ordered surface layer. Annealing to higher temperature resulted in the reappearance of the diffraction pattern associated with the 7×7 reconstructed Si(111) surface. This indicated three dimensional island growth. For the TiSi2 formed by in situ annealing of 50Å of Ti on Si(111), three different types of island morphologies were observed and identified as the C49 phase of TiSi2. The C49 TiSi2 was proven to be an epitaxial titanium silicideby HRTEM and SAD. Two different orientation relationships of the TiSi2 islands are found: 1) [3 1 1] C49 TiSi2 // [112]Si and (130) C49 TiSi2 //(11 1) Si, and 2) [1 1 2] C49 TiSi2 // [110] Si and (021) C49 TiSi2 //(1 11) Si. The C49 nucleation and island morphologies are discussed in terms of the character of the epitaxial interface.
Effects on TiN Film Properties of the Interaction Between Titanium and Borophosphosilicate Glass During High-Temperature Nitridation
Authors: Galovich C. S. , Lee S. S. , Kwong D. L.
Published: March 2011

Titanium nitride, formed either by rapid thermal processing (RTP) or reactive sputtering, is commonly applied as a barrier film in the fabrication of metal-to-substrate contacts for CMOS devices. In one approach a titanium film is sputtered onto a patterned dielectric and then nitrided at a temperature greater than 500° C to form a TiN layer. Variations in the structure and resistivity of the titanium layer are observed when the titanium overlies a borophosphosilicate glass (BPSG) film. The structural change appears as a “wrinkling” of the TiN film and the TiN/BPSG interface. More severely wrinkled films are characterized by lower sheet resistivities. Results of TEM and SEM analyses are presented, as well as data on TiN resistivity and reflectance for nitridation temperatures in the range 650°C to 900°C, and for BPSG boron and phosphorus concentrations of approximately 3 to 5 wt. %. Mechanisms for the TiN wrinkling are discussed.
Layer Formation in CuNi/C X-Ray Optics
Authors: Jankowski A. F. , Stearns D. G.
Published: March 2011

A series of Cu/C and CuNi/C multilayer films are prepared for potential use as normal incidence x-ray reflectors. The use of a metal alloy layer is intended to enhance layer formation without metastable metallic carbide formation. The films are characterized both in composition and structure. Addition of Ni to the Cu-rich layer is seen to markedly improve the formation of continuous metal layers.
Diffuse Light Scattering as a Probe of Buried Interface Reactions
Authors: Pantojas V. , Cabral C. , Harper J. , Persans P. D.
Published: March 2011

We report the application of diffuse light scattering to study buried interface reactions. As a model system we discuss the annealing of thin Cu/Al bilayers. Samples were prepared by evaporating Cu/Al and Al/Cu bilayers onto SiO2 covered Si wafers at room temperature. The Cu-Al thickness ratio was chosen to yield an average composition of CuAIt. When bilayers are annealed at 200–250°C the scattering intensity increases by about a factor of five above the as-deposited samples. We believe that this increase is partially due to the non-uniform reaction at the Cu/Al interface and partially to the mottled surface formed when leading growing parts of the reaction layer reach the surface. The relative contribution from this scattering mechanism is discussed quantitatively. For higher annealing temperature(300–350°C) the scattered light intensity falls again almost to the original level, suggesting that the Al/Cu reaction is complete and that the surface is homogeneous and smooth. For higher temperature anneals (400–500°C) the scattering once again increases, mainly due to the natural monotonic increase in surface roughness when metals are annealed. Control samples of the pure metal on Si02 show only the high temperature roughening effect.
Coarsening Phenomenon of Si Clusters
Authors: Kumomi Hideya , Yonehara Takao
Published: March 2011

Coarsening phenomenon is observed among crystalline Si clusters which are deposited over silicon-oxide and -nitride surfaces by chemical vapor deposition using HC1 as an etching gas. As soon as the deposition starts, submicron-sized fine clusters nucleate and increase in number, but do not grow in size. Micron-sized large clusters emerge among the fine ones, gradually increase and rapidly grow, while the preexisting fine ones disappear finally. It is found that the fine clusters must be etched away into vapor again by HCl or reevaporated.
Time Dependent Deformation in Polymers
Authors: Shinozaki D.M. , Klauzner A.
Published: March 2011

Time dependent deformation of polymers must be considered in studies of deformation and fracture of polymer electronic packaging materials. In composites in which fabrication stresses are stored, the rate of plastic relaxation influences the long term mechanical stability. The practical need to predict mechanical performance of these materials from simple mechanical tests is the motivating factor in attempting to relate fundamental mechanisms of deformation to the stress relaxation behaviour. A review of some approaches based on activated rate processes and their application to some preliminary experiments onpolyimide is reported.
Thermal Properties Evaluation of Thin Films, Wafers And Substrates
Authors: Tye R.P. , Maesono A.
Published: March 2011

Materials in use or under consideration for many applications in new and emerging technologies are often available only in small quantities and many times in the form of thin films, wafers and sheets. Such size and form limitations present a number of challenges to those wishing to evaluate thermal performance characteristics. This has resulted in a need to develop totally new transient or modify current transient and steady state techniques significantly. Various new or modified techniques to measure thermophysical properties are described. Illustrations of, applications to and results on semiconductors, superconductors, diamonds, polymers, composites and layered structures will be discussed.
Toward Measurement of Thin Film Properties by Enhanced Moire Interferometry
Authors: Voloshin Arkady S. , Erdogan Fazil , Tsai Leng-Tsun
Published: March 2011

Growing use of thin films in encapsulated integrated circuits(IC's) necessitated new developments in measurement of their mechanical properties in-situ. This can be done by a hybrid analytical experimental approach. The films are approximated by orthotropic membranes and the substrate is assumed to be an elastic continuum. It can be shown that power of stress singularity is a function of geometry and film/substrate material properties. By loading the sample and measuring actual displacement field in the close proximity to the crack or edge, one can evaluate the needed properties.

The technique used to measure full field displacements is enhanced moire' interferometry. It is based on the formation of fringes by the coexistence of light wave fronts diffracted from a specimen grating of high frequency. These specimen gratings are created on the specimen surface using a replication technique from a specially prepared mold. Two beams of coherent laser light illuminate the specimen grating obliquely to create a virtual reference grating in front of the specimen. The frequency f of this grating is chosen to be 2400 lines/ mm, this corresponds to a sensitivity of 0.417 µk per fringe order. When the specimen is deformed the interference pattern (moire' fringes) is formed and collected by a video camera connected to a PC-based digital image processor. Analysis of the moire pattern results in full field displacement.
Grain Boundaries in High Thermal Conductivity Aluminum Nitride.
Authors: Mckernan Stuart , Norton M. Grant , Carter C. Barry
Published: March 2011

The benefits of AIN as a substrate material for the electronics packaging industry appear to be limited by the deleterious effects of boundaries in the polycrystalline material. Some observations on different types of boundary in AIN using several complementary techniques are reported.
Thermal Conductivity of Aluminum Nitride Thin Films
Authors: Shaw-Klein L. J. , Burns S. J. , Jacobs S. D.
Published: March 2011

Anomalously low laser damage resistance thresholds have been observed in many thin film systems. Thermal conductivity values well below bulk have been suggested as a possible cause. A series of reactively sputtered AIN films were deposited on fused quartz and sapphire substrates. Their thermal conductivities were measured using the thermal comparator technique. Important factors contributing to the apparently large thermal resistance in the AIN films include film surfaces, small grain size, and high oxygen concentration. Preferred orientation and columnar morphology also affect film conductivity. Film microstructures were observed by transmission electron microscopy, and correlated with measured values of thermal conductivity.
Interactions of Copper with Interlayer Dielectrics and Adhesion Promoters / Diffusion Barriers.
Authors: Arcot B. , Shy Y.T. , Murarka S.P. , Shepard C. , Lanford W.A.
Published: March 2011

Copper with its high conductivity, specific heat and melting point (compared to Al), is being investigated as the interconnection metal for applications both on and off the chip. Such interconnection wirings will be seperated by the dielectric layers which could be either polymers or inorganic oxides like SiO2. In such applications an adhesion promoter, which may also work as a diffusion barrier, maybe used between the dielectric and the metal film. An investigation of the diffusion and interaction of Copper with such dielectrics and insulators has been carried out in the temperature range of 200 – 500 ºC. Specifically, interactions of Copper with SiO2'P—glass, Polyimidesiloxane and Magnesium are investigated. Results of these studies will be presented and discussed.
Measurement of Mechanical Bulk- and Interfaceproperties of Thin Polymeric Films
Authors: Kim Kyung-Suk
Published: March 2011

Theoretical and experimental studies on the measurement of the mechanical constitutive relation and the interfacial strength for thin polymeric film structures are presented. For the measurement of the constitutive relation, a new innovative testing technique based on the J-integral concept is introduced. This method measures the stressstrain relationship in the thickness direction, while the stress-strain relationship in the lateral direction can be measured with conventional techniques. For the measurement of interface strength the cut test and the ball rolling test were used to construct the failure criteria, based on the interface fracture mechanics concept. The interface between polyimide and glass (SiO2) has been tested and analyzed in detail. This shows that the toughness of the PMDA-ODA polyimide/glass interface was measured as 2.2 J/m2 in pure opening mode and as 15 J/m2 for pure sliding mode. It was also observed that the PMDA-ODA/SiO2 interface toughness is insensitive to temperature variations in the range of 20ºC — 250ºC.
Low Temperature Deposition of High Dielectric Constant Thin Films for Decoupling Capacitor Applications
Authors: Li P. , Gittleman B. , Lu T.-M.
Published: March 2011

High dielectric constant thin films for packaging applications were studied. Compared with polycrystalline or epitaxial ferroelectric thin films amorphous ferroelectric films are a promising alternative because of their ease of processing and low leakage current. Reactive Partially Ionized Beam deposition (RPIB) offers a new approach to deposit high dielectric constant films at a low substrate temperature. As an example, the growth of amorphous BaTiOs thin films using RPIB deposition is described. The films were characterized in terms of dielectric constant and leakage current. The annealing effects on the film properties are also discussed.
The Effect of Sputtering Conditions on Submicron Contact Filling Using Laser Planarization
Authors: Yu C. , Doan T.T. , Kim S. , Sandhu G.S.
Published: March 2011

The effect of sputtering conditions of Al alloy films on the ability to fill submicron contact/vias by laser planarization has been investigated. A significant improvement in the process window (complete contact filling to optical ablation) has been observed by using high temperature and/or bias sputtering. In general, the process window increased with the increasing deposition temperature and substrate bias voltage. For 0.9 μm diameter contacts of aspect ratio ∼ 1, the process window for contact filling by AlSi(l%)Cu(0.5%) increased from 5% for standard deposition parameters to a record high 30% by using the optimized sputtering conditions.
Effect of Oxygen Exposure and Deposition Environment on Thermal Stability of Ta Barriers To Cu Penetration.
Authors: Bojarczuk N.A. , Clevenger L.A. , Holloway K. , Harper J.M.E. , Cabral C. , Schad R.G. , Stolt L.
Published: March 2011

The effect of deposition pressure and controlled oxygen dosing on the diffusion barrier performance of thin film Ta to Cu penetration was investigated. In-situ resistivity, Auger compositional profiling, scanning electron microscopy and cross-sectional transmission electron microscopy were used to determine the electrical, chemical and structural changes that occur in Cu/Ta bilayers on Si upon heating. A 20 nm Ta barrier allowed the penetration of Cu at temperatures ranging from 320 to 630°C depending on processing conditions. Barrier failure temperature is dependent upon the deposition pressure and oxygen contamination at the Ta/Cu interface. This indicates the importance of understanding how deposition conditions affect diffusion barrier performance.
Application of Superplasticity in Solder Joints
Authors: Shine M. C. , Seyyedi J. , Massingill T. , Mei Z. , Morris J. W.
Published: March 2011

The lifetime of non-compliant eutectic solder joints was improved by an order magnitude by rapid quenching. The quenching produces a fine equiaxed superplastic grain structure which lowers the stresses in the solder joints for the fatigue cycle strain range. Similarly, compliant J Bend and Gull wing joints, which last thousands of cycles, operate at lower stresses where superplastic deformation predominates.
Flip-Chip Bump Bonding Reliability and Process Improvement
Authors: Koh Wei H. , Mayemura S. , Kuipers W.
Published: March 2011

Long term reliability of flip-chip bump bonding for application in infrared detector interconnection is investigated. The effectiveness of a thin film nickel as diffusion barrier for reducing indium-gold intermetallic formation is studied by accelerated life test and destructive physical analysis. A new interconnect structure replacing the conventional bump-to-bump configuration is described.
MOCVD of GaN Using Diethylgalliumazide and Ammonia
Authors: Ho Kwok-L. , Jensen Klavs F. , Hwang Jen-W. , Evans John F. , Gladfelter Wayne L.
Published: March 2011

GaN thin films have been deposited on Si and sapphire substrates by metalorganic chemical vapor deposition (MOCVD) using diethylgalliumazide and ammonia. Films were grown in the temperature range of 500-750°C. Growth rates were monitored in situ using laser interferometry. The addition of ammonia enhanced the growth rate significantly. At high temperatures, gas-phase depletion of the precursor reduced the growth rate of GaN. Films grown on (0001)-oriented sapphire substrates at temperatures above 650°C were highly textured with smooth surface morphology. Optical and electrical properties of the films are discussed and compared to those of films grown using conventional Ga and N sources.
The Use of Tris(Trimethylsilyl)Arsine to Deposit GaAs by OMCVD
Authors: Berry Alan D. , Purdy Andrew P. , Wells Richard L. , Pasterczyk James W. , Johansen James D. , Pitt Colin C.
Published: March 2011

Chemical vapor deposition experiments using (Me3Si)3As with either GaCl3 or Me3Ga at ambient pressure have produced films of GaAs on Si and semi-conducting GaAs substrates. The films have been characterized by X-ray diffraction and Auger electron spectroscopy, and each have small amounts of C and O impurities. No desired films were deposited from (C6F5)3GaAs(SiMe3)3 at 500°C and low pressures.
A Comparison of Arsine and Tertiarybutylarsine as Precursors for the Selective Epitaxial Growth of GaAs and AlGaAs
Authors: Smith F.T.J.
Published: March 2011

We have investigated the use of tertiarybutylarsine (tBAs) as an As source in the surface-selective growth of GaAs and AlGaAs by low-pressure OMVPE. Deposition was carried out onto GaAs substrates partly masked with SiNx. Triethylgallium (TEGa) and trimethylaluminum (TMAl) were used as precursors along with either arsine or tBAs. Growth pressures were in the range 0.3 to 3.0 Torr. The usual trends of decreasing deposition on the mask with increasing temperature, decreasing group V/III ratio, and decreasing pressure were observed. At very low group V/III ratios, for either As precursor, single crystal material with a pitted surface was obtained. A reduction in the nucleation of polycrystalline material on the mask was observed when tBAs was used in place of AsH3.
High Performance 0.5 and 0.25 μm Gate GaAs Mesfet Grown by MOCVD Using Tertiarybutylarsine
Authors: Sundaram V.S. , Mao B.-Y. , Zurek S.J. , Levy H.M. , Lee G.Y. , Fraas L.M.
Published: March 2011

Using tertiarybutylarsine and trimethylgallium a GaAs MESFET structure was grown and fabricated into half and quarter micron devices. The typical transconductance and unity current gain frequency (ft) for the half micron device were 360 mS/mm and 24 GHZ respectvely. The corresponding numbers for the quarter micron devices were 510 mS/mm and 55 GHZ respectively.
Decomposition Mechanisms of Antimony Source Compounds for Organometallic Vapor-Phase Epitaxy
Authors: Larsen Cory A. , Gedridge Robert W. , Li Shin Hwa , Stringfellow Gerald B.
Published: March 2011

The decompositions of tertiary stibines (R3Sb, R = methyl, vinyl, isopropyl) were studied in an atmospheric pressure flow tube reactor, using D2 and He as carrier gases. D2 was used to isotopically label the byproducts in order to elucidate the pyrolysis mechanism. The exhaust products were analyzed by a time-of-flight mass spectrometer. The decomposition of these tertiary stibines in the presence of group Ill precursors was studied in order to simulate the conditions of organometallic vapor phase epitaxial growth. A comparison between the pyrolysis temperatures, decomposition mechanisms, and surface area effects of these Sb source compounds is presented.
Polychalcogenide Complexes as Low Temperature Precursors for Quantum Size and Bulk Binary and Ternary Semiconductors
Authors: Dhingra Sandeep , Kim Kang-Woo , Kanatzidis Mercouri G.
Published: March 2011

We report the utility of \Cd(Se4)2]2-, \Cu4Se12]2- and \In3Se15]3- as convenient low temperature precursors to semiconducting CdSe and CuInSe2. DMF and DMSO solutions of these complexes react with Se-abstracting reagents such as CN- and n-(Bu3)P to yield the corresponding binary solids at 155 °C or less. Appropriate stoichiometric mixtures of \Cu4Se12]2- and \In3Se15]3- react to give CuInSe2. The semiconducting solids were characterized with UV/vis spectroscopic, X-ray crystallographic and electron (scanning and transmission) microscopic techniques. The particle size of these materials can range from the quantum-size regime to the bulk regime, depending on the reaction conditions, metal precursor complex and Se-abstracting reagent used.
The Incorporation and Behavior of Oxygen in AlGaAs Grown by Mombe Using Trimethylamine Alane
Authors: Abernathy C. R. , Song J. , Hobson W. S. , Pearton S. J. , Ren F. , Bohling D. A. , Muhr G. T.
Published: March 2011

Trimethylamine alane (TMAAl) has been demonstrated to be a superior Al precursor for growth of AIGaAs by metal-organic molecular beam (MOMBE). TMAA1 reduces both carbon and oxygen contamination relative to the standard Al source, triethylaluminum (TEA1). However, AlGaAs grown with TMAAl still shows a residual oxygen background of ∼2 × 1018 cm−3 when used with triethylgallium (TEGa) and either As4 or ASH3. This background is independent of Al mole fraction and is due primarily to alkoxides in the TEGa. AIGaAs grown with TMAAl and elemental Ga contains oxygen at levels commonly obtained in MBE, −2 × 1017 cm-3. While an oxygen level of −2 × 1018 cm-3 is not desirable, we have found that most of this impurity is electrically inactive as evidenced by room temperature photoluminescence and n-type dopant activation. In light of this, we have assessed the applicability of AlGaAs grown with TMAAl to the fabrication of high-speed GaAs/AIGaAs devices. The source is found to be suitable for structures like the heterojunction bipolar transistor.
Analysis of the Physical and Chemical Factors Determining Compositional Variations in the MOCVD Growth of Indium Gallium Arsenide
Authors: Einset Erik O. , Jensen Klavs F. , Kuech Thomas F.
Published: March 2011

We present an analysis of compositional variations in the growth of the compound semiconductor, InxGal-xAs, by metal organic chemical vapor deposition (MOCVD). A three dimensional transport model for fluid flow, heat, and mass transfer is solved using the finite element method. The Delta Lattice Parameter (DLP) model is used to describe the thermodynamics of the solid solution, and the Hertz-Langmuir equation is used to calculate the evaporation rate of indium from the growing crystal. Wall depletion is incorporated by allowing for explicit wall deposition of In vapor throughout the reactor.

Comparison of model predictions with experimental observations by MOCVD of InGaAs in a horizontal reactor suggests that transport phenomena lead to composition variations across the substrate, and that solution thermodynamics have little effect on the InAs incorporation rate at a given deposition temperature. However, thermodynamic factors appear to influence the change in indium incorporation with growth temperature.
The Surface Chemistry of Si/Ge Deposition
Authors: Crowell John E. , Lu Guangquan , Ning Bob M. H.
Published: March 2011

Reaction processes leading to the deposition of Si and Ge epilayers have been delineated using a combination of surface spectroscopies. The dissociative adsorption of disilane and digermane has been investigated on the Ge(111) surface using multiple internal reflection infrared spectroscopy (MIRIRS). Molecular adsorption of Si2H6 and Ge2H6 occurs for adsorption below 150K. Molecular and dissociative adsorption are competitive processes at 110-140K. Dissociative adsorption of Si2H6 and Ge2H6 occurs above 150K. Trihydride formation (SiH3 and GeH3) is favored near 150-200K, while Si-H and Ge-H bond scission becomes significant above 200K. Di- and trihydrides are dominant below 300K, while the monohydrides are most prevalent above 300K. Decomposition of all surface hydrides occurs by 600K. On the Si(100) surface, digermane adsorption leads to the deposition of a Ge overlayer. Hydrogen desorption from the Ge/Si(100) surface is strongly altered with respect to the clean Si surface. The observed desorption behavior has important consequence on the low temperature deposition of Sil-xGex by thermal CVD.
Surface Chemistry of Silicon and Germanium Treated with Hydrofluoric Acid Solutions: Slow Reactions of Process Residuals
Authors: Yota J. , Burrows V.A.
Published: March 2011

Solutions of hydrofluoric acid are used extensively in the processing of semiconductors, primarily in etching and in oxide stripping procedures. Such solutions are often buffered with ammonium fluoride to insure constant oxide stripping rates. Infrared spectroscopy of silicon and germanium surfaces treated with such solutions indicates that a thin film of ammonium salts will deposit on the materials unless they are immediately and very thoroughly rinsed following treatment. This thin film, comprised initially of ammonium bifluoride (NH4FHF), reacts with the semiconductor material to form ammonium fluoride (NH4F) as a reactive intermediate, and ammonium hexafluorometallate ((NH4)2 SiF6 or (NH4)2 GeF6). These reactions occur very slowly, over hours or days. They are apparently driven by favorable thermodynamics. This explanation is supported by the absence of comparable reactions using analogous chlorine-based solutions (HCI/NH4 CI). Aspects of the reaction mechanism for hexafluorometallate production is presented.
Chemically Assisted Ion Beam Etching of SiGe
Authors: Glembocki O.J. , Prokes S.M. , Stahlbush R.E.
Published: March 2011

Chemically assisted ion beam etching (CAIBE) of Si1−Gex films is reported. Ar+ ion sputtering in the presence of Cl2 background gas has been used to etch epitaxial films of Si1−xGex, with x ranging between 0 and 0.5. It is found that Si1−xGex, sputters more rapidly than Si, but less than Ge. The use of C12 gas enhances the sputter rates of SiGe as in the case of Si. Analysis of the etch rates indicates that the etch rate increase is due to an enhancement of the sputtering process, rather than a chemical effect.
The Deposition of Aluminum and Aluminum Boride Thin Films by Aluminaborane Cluster Compounds
Authors: Glass John A. , Kher Shreyas , Hersee Stephen D. , Ramseyer G. , Spencer James T.
Published: March 2011

The preparation of aluminum-containing thin film materials by MOCVD and MOMBE for use in III-V semiconductor materials, such as HEMT devices, is currently under active investigation. The preparation of uniform, conformal aluminum and boron containing thin film materials from the chemical vapor deposition (CVD) of aluminum borane cluster precursor compounds has been studied. A variety of substrates, deposition conditions and aluminaborane precursors have been explored and their effect on film composition, growth rate and thin film morphology has been investigated. The thermal depositions of aluminum and boron-containing thin films from aluminum borohydride, AI(BH4)3, on copper, SiO2 and GaAs are reported. Boron incorporation in the films vary depending on substrate temperature, aluminaborane flow and the presence or absence of a H2 carrier. These films have been characterized by SEM, AES and XES.
Morphology and Deposition Conditions of CVD Au Films
Authors: Holloway Karen , Zuhoski Steven P. , Reynolds Scott , Matuszewski Christine
Published: March 2011

The chemical vapor deposition of Au films by thermal decomposition from an organometallic precursor [dimethyl 1,1,1,5,5,5-hexaflouro-2,3-pentanedionato Au (III)] has been investigated for application as a interconnection metallization. The morphology and feature fill properties of deposits obtained using H2 and N2 carrier gases and varying pressure and temperature conditions were observed by cross-section scanning and transmission electron microscopy (SEM and TEM). Line patterns etched in SiO2 with aspect ratios up to 1.5 filled with few or no voids at a growth temperature of 250°C. For films deposited in H2 the Au grain size is large (on the order of the feature size). In unetched areas, however, large (600 nm) triangular-shaped structures protrude from the deposit. TEM observation shows that these structures are single-crystal Au dendrites which contain a central twinned region. Au films grown at 275°C had poor hole fills with large, irregular voids. These films exhibited large protrusions which occluded the lines and halted growth in these areas. The deposit morphology suggests a low reaction probability except at preferred crystal sites.
The Deposition of Nickel Boride Thin Films by Borane and Metallaborane Cluster Compounds
Authors: Glass John A. , Kher Shreyas , Kim Yoon-Gi , Dowben P.A. , Spencer James T.
Published: March 2011

The deposition of high purity and controlled stoichiometry metal boride thin-film materials has recently received considerable interest. Borane clusters and their corresponding metal complexes are currently being investigated in our laboratories for their utility as unique source materials for the formation of metallic boride thin films by MOCVD. Variable composition nickel boride thin films ranging from 0.1 micron to several microns have been prepared. These new materials have been characterized by SEM, AES and XES. The magnetic properties of these new films have been investigated with torque magnetometry and magneto-optic Kerr effect magnetometry.
Halogenation of Diamond (100) Using Atomic Beams
Authors: Freedman Andrew , Stinespring Charter D.
Published: March 2011

Diamond (100) substrates have been halogenated under ultrahigh vacuum conditions using atomic beams of chlorine and fluorine. X-ray photoelectron spectra of the resulting samples indicate that saturation levels of less than a monolayer occur for both species. The fluoride adlayer is stable up to 700 K and slowly desorbs at temperatures above this temperature. In contrast, the chlorine adlayer starts to desorb above 223 K, the lowest temperature sampled.
Characteristics of Oxide Layer Grown on Gallium Arsenide Using 2.8-eV Translational Energy Atomic Oxygen
Authors: Cross J.B. , Hoffbauer M.A. , Farr J.D. , Glembocki O.J. , Bermudez V.M.
Published: March 2011

Oxide layers that are thick (>200 Å and uniform have been produced on GaAs (110) and (100) by reacting the substrate (Ts<160°C) with high translational energy (1-3 eV) neutral atomic oxygen at flux levels of∼50 monolayers/second. The Ga and As species are formed in their highest oxidation states, which implies formation of either Ga2O3 and As2O5 or GaAsO4. Raman spectroscopy indicates that there is no metallic (amorphous or crystalline) As in the oxide or at the interface between the oxide and substrate and that there is no appreciable oxidation induced disorder of the substrate as is seen in high temperature thermal oxidation processes.
Trimethylamine Gallane as a Precursor to Cubic Gallium Nitride and Gallium Arsenide. Metal Hydride Chemical Vapor Deposition
Authors: Gladfelter Wayne L. , Hwang Jen-Wei , Phillips Everett C. , Evans John F. , Hanson Scott A. , Jensen Klavs F.
Published: March 2011

Cyclo-trigallazane, [H2GaNH2]3, is known to form bulk powders of the new cubic phase of gallium nitride upon pyrolysis. An explanation for this unusual example where the molecular structure of the precursor controls the crystal structure of the solid state product is presented. In a hot-wall atmospheric pressure chemical vapor deposition (CVD) reactor, arsine was found to react with TMAG to form films of polycrystalline GaAs which were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The growth rates for smooth films was 1-4 μm/h. In a low pressure CVD reactor, elemental arsenic vapor was also found to react with the TMAG to give GaAs thin films.