bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Film Composition Transition Phenomena in the Copper Oxide Metal Organic Chemical Vapor Deposition (MOCVD) Studied by Scanning Electron Microscopy (Sem)
Authors: Chang Yu-neng 
Published: March 2011

ABSTRACTIn this report, the impact of deposition temperature variation on the evolution of film morphology and microstructure was studied. In the copper oxide metal organic chemical vapor deposition (MOCVD) process, a temperature gradient was created on the substrate surface. By using a specific design of the heating susceptor, the local temperature of the leading edge (upstream) on the substrate surface was maintained at 70°C lower than the temperature of the ending (downstream) edge. The evolution of local composition and microstructure in deposited films were analyzed by X-ray diffraction (XRD), transmission Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and SEM. From XPS and XRD results, Cu2O rich phase was deposited at the low temperature area, while CuO rich phase was deposited at the high temperature area. These two areas were divided by a phase intermixing (transition) zone of 40–100 ums wide. The temperature of this abrupt Cu2O->CuO deposition product transition was determined to be 390°C -400°C. As indicated by SEM results, the low temperature favorite Cu2O continuous phase, collapsed into coarse grains (with the scale of 10 urn) first, then became fine grains among channels of CuO phase, and finally diminished into the high temperature favorite CuO continuous phase. Spatially resolved XPS results also indicated that the film composition changed abruptly through the transition zone. A nucleation-growth competition mechanism, between the Cu2O rich phase and the CuO rich phase, was suggested to occur in this zone. In this model, this dynamic deposition product transition is interpreted by the temperature dependency of nucleation rates for the specific CuO phase or Cu2O phase.
Deposition and Characterization of MgO Thin Films on SrTiO3 and LaAlO3 Substrates
Authors: Chang Bertha P. , Sonnenberg Neville , Cima Michael J. 
Published: March 2011

ABSTRACTMgO thin films have been deposited on SrTiO3 and LaA1O3 substrates using both off-axis rf magnetron sputtering and electron beam evaporation techniques. The effects of substrate material, temperature, film thickness, deposition rate, sputtering gas, and pressure on the quality of the MgO films produced have been studied. Films deposited on (100) SrTiO3 at temperatures > 300°C display only the (h00) reflections in their X-ray diffraction traces, with narrow X-ray rocking curve measurements indicating that these films are epitaxial. Epitaxy has been confirmed with grazing incidence diffraction. MgO films deposited on (100) LaAlO3 are crystalline, but have varying orientations depending on the film thickness. From scanning electron microscopy, MgO films on SrTiO3 substrates appear smooth and dense while those deposited on LaAlO3 substrates possess rougher surfaces. Surface morphologies have been analyzed using atomic force microscopy.
Structural Instability of the Ceramic Coating in a Metal-Ceramic Composite Induced Through Control of Chemistry of the Bonding Atmosphere
Authors: Ray Abhijit 
Published: March 2011

ABSTRACTA novel processing technique has been developed to coat Al2O3 on Nb in an argon atmosphere with very low O2 content. It has been proposed1 that the low O2 content helped to increase the defect concentration in the ceramic phase resulting in an enhanced diffusion of Nb into Al2O3 at the metal-ceramic interface at a relatively low bonding temperature. A mathematical model has been developed1 to understand the effect of purified bonding atmosphere on interfacial diffusion. While diffraction studies in the transmission electron microscope revealed1 extensive amorphization at the metal-ceramic interface, EDX analysis showed1 that the interfacial amorphous phase has a very high concentration of O. Additionally, this phase is found to contain Al and Nb. The interfacial phase is formed due to the diffusion of Nb into the ceramic phase. The paradoxical phenomenon of O enrichment of the interfacial amorphous phase in a low O2 containing bonding atmosphere is due to the loss of gaseous oxides of Al from this phase. These oxides have relatively less proportion of O compared to Al2O3. Continuous loss of such oxides from the amorphous phase to the gaseous phase will, therefore, result in an O to Al ratio (in the amorphous phase) far exceeding that in Al2O3 (3:2).
Detailed Characterisations of GaAs Films on Si Obtained by Conformal Growth.
Authors: Gerard B. , Pribat D. , Bisaro R. , Costard E. , Nagle J. , Ricciardi J. , Dupuy M. 
Published: March 2011

ABSTRACTConformal growth is a confined epitaxial lateral overgrowth technique capable of yielding low dislocation density GaAs films on Si. This technique makes extensive use of selective epitaxy and crystal growth is confined by a dielectric cap as well as by the self-passivated Si surface itself.In this paper, we have performed a detailed characterisation of the state of stress of the GaAs films in various configurations (after conformal growth and removal of the seed regions, and after the regrowth of an MBE layer) by photoluminescence measurements at 5K and X-ray diffraction experiments. Although the as-grown conformal films are found in the same state of stress than reference MOCVD GaAs epilayers on Si, we report a significant decrease of this stress after MBE regrowth on conformal films.
Mechanism for Step Growth on Diamond (100)
Authors: Zhu Mei , Hauge Robert H. , Margrave John L. , D'Evelyn Mark P. 
Published: March 2011

ABSTRACTA model for diamond growth on stepped diamond (100)2×1 surfaces is proposed, involving adsorption and reaction of CH3 and H on a dimer-reconstructed surface. Surface rearrangments and the breaking of C-C dimer bonds by H and/or H2 are suggested to be important The energetics were estimated by molecular mechanics (MM3). Growth is concluded to occur predominantly by extension of dimer rows, yielding a smooth surface, due to steric and bond-strain constraints on the positions of precursor-addition reactions and the kinetic stability of type SB steps against etching.
Diamond Nucleation During Biased Chemical Vapor Deposition
Authors: Csencsits Roseann , Rankin Janet , Boekenhauer Rachel E. , Kundmann Michael K. , Sheldon Brian W. 
Published: March 2011

ABSTRACTThe initial stages of bias-enhanced chemical vapor deposition (CVD) of diamond were investigated in a microwave-plasma system. Samples were characterized with TEM and concurrent electron energy loss spectroscopy (EELS) to characterize chemical bonding in the deposited material. The results show that a thin amorphous carbon film is deposited during biasing, and that diamond nucleation occurs on this amorphous film. Isolated regions of crystalline SiC within the amorphous layer were also observed at longer bias times. These regions apparently form by a reaction between the amorphous carbon layer and the silicon substrate.
Metastable Structural Surface Excitations and Concerted ad Atom Motions: A Stm Study of Atomic Motions Within a Semiconductor Surface
Authors: Golovchenko Jene , Hwang Ing-Shouh , Ganz Eric , Theiss Silva K. 
Published: March 2011

ABSTRACTKnowledge about atomic scale motions is essential to the understanding of dynamical phenomena on surfaces, such as diffusion, phase transitions, and epitaxial growth. We demonstrate that the addition of a very small number of Pb atoms to a Ge(111) surface reduces the energy barrier for activated processes, thus allowing one to observe concerted atomic motions and metastable structures on this surface near room temperature using a tunneling microscope. The activation energy for surface diffusion of isolated substitutional Pb atoms in Ge(111)-c(2×8) was measured by observing individual atomic interchanges from 24°C to 79°C. We also observed the formation and annihilation of metastable structural surface excitations, which are associated with large numbers of germanium surface atoms in one row of the c(2×8) reconstruction shifting along that row like beads on an abacus. The effect provides a new mechanism for atomic transport on semiconductor surfaces and can explain a number of other observed phenomena associated with Ge(111) surfaces, including the surface diffusion of Pb atoms.
Dry Surface Cleaning of Plasma-Etched Hemts
Authors: Pearton S. J. , Ren F. , Katz A. , Chakrabarti U. K. , Lane E. , Hobson W. S. , Kopf R. F. , Abernathy C. R. , Wu C. S. , Bohling D. A. , Ivankovits J. C. 
Published: March 2011

ABSTRACTFabrication of sub-micron high electron mobility transistors (HEMTs) involves dry etch removal of GaAs from an underlying AlGaAs or InGaAs stop layer. The etch selectivity is achieved by formation of AlF3 on AlGaAs, or InCl3 and InF3 on InGaAs, which must be removed before processing can proceed. Wet chemical cleaning has difficulty in such a situation because of surface tension effects. We have investigated use of Electron Cyclotron Resonance (ECR) H2 or Ar discharges, or hexafluoroacetylacetone (HFAC) vapor, for in-situ dry etch cleaning of HEMTs exposed to low bias BCl3/SF6 discharges. The HFAC vapor can remove most of the remnant fluorine, but is effective only when the sample is heated above ∼250°C. This relatively high temperature is not compatible with in-situ cleaning of the etched device. Low-bias(−75V) sputter cleaning with an Ar discharge removes all remnant Cl and ∼40% of the F, but dc biases above -125V are required for complete cleaning, and this ion bombardment can lead to damage in the HEMT. ECR H2 discharge exposure is effective in removing all Cl- and F-related residues in a short period (∼5 mins) with low dc biases (−25 V) on the sample.
Disordering of a Short Period GaAs-AlGaAs Superlattice by C Diffusion
Authors: Jamal Z. , Goodhew P. J. 
Published: March 2011

ABSTRACTCarbon doping of GaAs and AlGaAs is easily carried out during chemical beam epitaxy by controlling the proportions of the precursors trimethylgallium and triethylgallium. The diffusion of C introduced at levels of up to 1020 cm−3, has been studied by SIMS and by TEM. In the latter case the destruction of short period GaAs-Al.3Ga.7As superlattices was monitored in order to assess the extent of diffusion after annealing at 800°C. The results confirm that C is quite a stable dopant. In addition, the destruction of the superlattices indicates that the diffusion mechanism of C involves group III sublattice sites.
Laser-Chemical 3-D Micromachining
Authors: Bloomstein T. M. , Ehrlich D. J. 
Published: March 2011

ABSTRACTThree-dimensional parts are machined in silicon using laser-induced chlorine etching reactions. Structures are created directly from solid-modeling computer-aided-design/computer-aided-manufacturing software. Removal rates exceeding 2×104 and 105μm3/s, several orders of magnitude faster than electrodischarge machining methods, are achieved at 1-μm, and 15-μm x-y resolution, respectively. Laser-induced metallization of resulting structures as well as replication through compression molding have been demonstrated.
Covalent Nitrides for Maskless Laser Writing of Microscopic Metal Lines
Authors: Maya Leon 
Published: March 2011

ABSTRACTSelected covalent metal nitrides with limited thermal stability, such as Sn3N4, Cu3 N, and Ni3N, were prepared in a glow discharge system by reactive sputtering in a nitrogen plasma. These compounds were characterized by chemical analysis and their thermal behavior established by temperature-programmed thermal decomposition. These materials decompose into the elements with the rate reaching a maximum at 615, 465, and 405 °C for Sn, Cu, and Ni respectively. The feasibility of using these coatings to generate metal lines by maskJess laser writing was explored. Conductingmetal lines, a few micron in width, could be generated with each of these nitrides. The resistivities of the metal lines were within an order of magnitude of those of the bulk metals for Cu and Ni and somewhat more for Sn.
Highly Reliable WGe Ohmic Contact to GaAs-AlGaAs HBTs
Authors: Fullowan T. R. , Ren F. , Tseng B. , Pearton S. J. , Abernathy C. R. , Harriott L. R. , Lane E. 
Published: March 2011

ABSTRACTWe report a highly reliable, sputtered WGe emitter contact for npn heterojunction bipolartransistors. A specific contact resistance of 7.5 × 10−7 Ω-cm2 and a transfer resistance of 4.0 × 10−2 Ωmm were obtained after 380°C, 1 min alloy. The contact was patterned by SF6 dry etching at low bias using a Au mask. This novel contact has comparable resistance to conventional AuGe-based metallization while having superior thermal stability. We have studied the dependence of contact properties on the post-deposition annealing conditions by transfer length method of electrical characterization and Auger analysis, and will also report long-term reliability results in comparison to AuGe-based metallization.
Study of the Thermal Stability of the Schottky Contacts on GaInP Grown by LP-MOCVD
Authors: Chang Edward Y. , Lai Yeong-Lin , Lin Kuen-Chyuan , Chang Chun-Yen , Juang F. Y. 
Published: March 2011

ABSTRACTThermal stability of the Schottky contacts on Ga0.51In0.49P has been made. The Ga0.51In0.49P epitaxial layer was successfully grown on the GaAs substrate by LP-MOCVD to form a lattice-matched heterostructure. In this paper, materials aspects of the Ga0.51In0.49P layers were characterized and thermal stability of three different types of films, including single-layer metal (Pt, Ni, Pd, Au, Co, Mo, W, Cr, Ti, Al, Ta, and In), metal silicides (WSi2, W5Si3, PtSi, and Pt2i), and TiW nitrides (TiWNx ) as the Schottky contacts materials on Ga0.51In0.49P were studied. Due to the high bandgap nature of Ga0.51In0.49P, the Schottky contacts on Ga0.51In0.49P demonstrate good characteristics. The barrier heights range from 0.79 to 1.19 eV depending on the selection of the materials and the annealing conditions. For single-metal contacts, Pt film shows the best thermal stability, the barrier height of 1.09 eV and the ideality factor of 1.06 were obtained for the Pt Schottky diode with furnace annealing at 500 °C for 30 min. For refractory compound films, the TiWNx film shows the best thermal stability. The TiWNx Schottky contacts demonstrate excellent electrical as well as physical characteristics, even after high temperature annealing at 850°C.
Tri-Layer Lift-off Metallization Process Using Low Temperature Deposited SiNx
Authors: Lothian J. R. , Ren F. , Pearton S. J. , Chakrabarti U. K. , Abernathy C. R. , Katz A. 
Published: March 2011

ABSTRACTA tri-level resist scheme using low temperature (<50°C) deposited SiNx ratfier than Ge for the transfer layer has been developed. This allows use of an optical stepper for lithographic patterning of the emitter-base junctions in GaAs/AlGaAs heterojunction bipolar transistors (HBTs) where a conventional lift-off process using a single level resist often leads to die presence of shorts between metallizations. The plasma-enhanced chemically vapor deposited (PECVD) SiNx shows a sligtly larger degree of Si-H bonding compared to nitride deposited at higher temperature (275°C), and is under compressive stress (-5 × 1010 dyne · cm−2) which is considerably relieved upor thermal cycling to 500°C (-1.5 × 1010 dyne · cm−2 after cool-down). This final stress is approximately a factor of two higher man conventional PECVD SiNx cycled in the same manner. The adhesion of the low temperature nitride to die underlying polydimediylglutarimide (PMGI) base layer in the tri-level resist is excellent, leading to high yields in the lift-off metallization process. These layers are etched in Electron Cyclotron Resonance (ECR) discharges of SF6 or O2, respectively, using low additional dc bias (≤-100V) on the sample. Subsequent deposition of the HBT base metallization (Ti/Ag/Au) and lift-off of the tri-level resist produces contacts with excellent edge definition and an absence of shorts between metallization.
Fundamental Studies of TiN Film Growth by CVD From Ti(N M e2)4 and Ammonia
Authors: Prybyla J. A. , Chiang C.-M. , Dubois L. H. 
Published: March 2011

ABSTRACTTiN films were grown by CVD from Ti(N M e2)4 and ammonia using a novel gas delivery system which allowed the sample to be kept in high vacuum while the reactants were mixed at elevated pressures. The object was to study fundamental chemistries and growth properties. We obtained clean (<5% carbon), near-stoichiometric (Ti:N = 1.15+/-0.1) TiN films. The gas phase chemistry was studied by mass spectrometry while the films were analyzed in situ by Auger electron spectroscopy (AES), and then removed for Rutherford backscattering (RBS) analysis. Film quality was studied as a functionof reactant ratio, substrate temperature, and reactant gas pressure. We obtained definitive information on the growth mechanism. Isotopic substituiton experiments establish that a rapid transami-nation reaction occurs in the gas phase. Mass spectrometry experiments indicate that the reactive intermediate is polymeric, consisting of Ti, N, H, arid perhapscarbon. Growth on patterned wafers shows that this intermediate has a high sticking coefficient and a low surface mobility at 300°C. These findings are considered in terms ofthe potential of this precursor system to be used in manufacturing.
Consecutive Selective Chemical Vapor Deposition of Copper and Aluminum from Organometallic Precursors
Authors: Fine Stephen M. , Dyer Paul N. , Norman John A. T. 
Published: March 2011

ABSTRACTFor the next generation of integrated microcircuits, there exists a need in the electronics industry for high conductivity, electromigration resistant metallization that can be deposited selectivity by chemical vapor deposition techniques. This paper describes a new process for depositing copper/aluminum metallization selectively onto diffusion barrier surfaces in two consecutive steps. First copper is selectively deposited by OMCVD ontoa patterned diffusion barrier surface using a Cu(I)(hfac)(olefin) precursor. Selective copper deposition onto tungsten or titanium nitride is achieved at 150°C and 100 mtorr. Aluminum is then selectively deposited onto copper using trimethylaminealane as the OMCVDprecursor. Trimethylaminealane gives good selectivity for aluminum deposition onto coppersurfaces over a temperature range of 100–120°C without the use of a surface activating agent. A small amount of copper diffuses into the as deposited aluminum layer atthe low deposition temperature. Complete diffusion of copper into aluminum is achieved by a rapid thermal anneal at a higher temperature. The selectivity of aluminum deposition onto copper surfaces is far superior to that observed for aluminum deposition onto other metal surfaces.
Characterization of Palladium Acetylacetonate as a CVD Precursor for Pd Metallization
Authors: Kowalczyk Steven P. , Ldgdlund Michael , Fahlman Mats , Salaneck William R. 
Published: March 2011

ABSTRACTPalladium acetylacctonate has received much consideration as a possible precursor for chemical vapor deposition of metallic palladium films for a variety of microelectronic applications. We have studied the adsorption and decomposition of palladium acetylacetonate ongold, polyimide, silicon and silver surfaces to understand the initial mechanisms of metallic palladium film formation. In situ x-ray photoelcctron spectroscopy was used to characterized the films after adsorption and their decomposition after thermal treatment or laser irradiation.
Erbium-Doped Silicon Prepared by UHV/CVD
Authors: Beach David B. , Collins Reuben T. , Legoues Francoise K. , Chu Jack O. 
Published: March 2011

ABSTRACTErbium-doped silicon has been prepared using Ultra High Vacuum/Chemical Vapor Deposition (UHV/CVD). An erbium mctalorganic compound, tris-1,1,1,5,5,5-hexafluoro-2,4-pentanedionato erbium (111) (Er(HFAC)3), was used as the erbium source and silane was used as the silicon source. Films were deposited at 650 °C at a total pressure of 1 mtorr. Erbium concentrations between 8×1019and 1×1018Er atoms/cm3were prepared by varying the Er source reservoir temperature. Low temperature photoluminescence measurements showed strong emission at 1.54μm. The films are single crystal, but with a high concentration of threading defects.
The Reactivity of HCI and Methyltrichlorosilane with Silicon Carbide Surfaces
Authors: Allendorf Mark D. , Outka Duane A. 
Published: March 2011

ABSTRACTThis work explores the reactivity of HCI and methyltrichlorosilane (MTS) with polycrystalline β-silicon carbide (SiC) surfaces using temperature-programmed desorption (TPD) and Auger electron spectroscopy. HCl is a corrosive gas that inhibits SiC deposition. The results show that HCl is adsorbed by SiC, forming a stable surface chloride that could inhibit SiC deposition. TPD shows that chlorine desorbs as HCI or SiCl4, confirming that HCl can etch SiC surfaces. Desorption is rate-limited by the breaking of Si-Cl bonds. MTS is also adsorbed by SiC; its desorption is similar to that of HCI.
Growth of SiO2 on Si(111)7×7 Using SiCl4 and H2O
Authors: Wise Michael L. , Okada Lynne A. , Coon Peter A. , George Steven M. 
Published: March 2011

ABSTRACTThe controlled atomic layer growth of SiO2 insulating layers on silicon surfaces might be achieved through the sequential reaction of SiCl4 and H2O:(A) Si-Cl + H2O → Si-OH + HCl(B) Si-OH + SiCl4 → Si-O-SiCl3 + HCl.To explore this ABAB… binary reaction scheme, laser-induced thermal desorption, temperature-programmed desorption, and Auger electron spectroscopy techniques were utilized to measure the kinetics of H2O oxidation of a Si(111)7×7 surface that had been previously subjected to a saturation SiCl4 exposure. Reaction kinetics studies for the oxidation of the chlorinated surface revealed that the rate of oxygen gain and the rate of chlorine loss were equal at reaction temperatures between 200 K and 700 K. These results were consistent with a direct substitution reaction according to:(A) Si-Cl + H2O → Si-OH + HCl.Above 700 K, the amount of oxygen gain became progressively greater than the amount of chlorine loss. This behavior was associated with the thermal desorption of H2 and the resultant formation of new dangling bond sites for H2O adsorption. For all temperatures, the oxidation kinetics of the chlorinated surface were nearly equivalent to the kinetics for the oxidation of clean silicon. This surprising result indicates that chlorine sites and free dangling bond sites react with equal probability to H2O. The kinetics of SiCl4 deposition were also measured on a Si(111)7×7 surface previously exposed to a saturation H2O dose. This chlorination reaction occurred at a much slower rate and was not as amenable to UHV studies.
Control of Isotropic and Anisotropic Etching and Surface Cleaning of Silicon and Silicon Dioxide in a Hydrogen Plasma
Authors: Veprek S. , Wang Ch. , Ratz G. 
Published: March 2011

ABSTRACTWe present data on the temperature dependence of the etch rate of silicon and silicon dioxide in order to elucidate optimum conditions for the selective oxygen removal from the silicon surface. Both, the etching temperature and ion bombardment have a pronounced influence on the surface morphology. The conditions yielding a minimum surface roughness will be presented. A careful control of the oxygen impurities of the hydrogen plasma in the range between about 1–3 ppm and 60 ppm allow us to control the degree of anisotropy of etching of patterned silicon wafers.