bluuebunny/crossref_metadata_2025_split huggingface dataset:
Planarization of Cu and Ta Using Silica and Alumina Abrasives - A Comparison
Authors: Li Y. , Ramarajan S. , Hariharaputhiran M. , Her Y. S. , Babu S.V. 
Published: April 2011

ABSTRACTExperimental results on chemical mechanical polishing of copper and tantalum in the presence of different chemicals, such as Fe(NO3)3, H2O2 and glycine, using both silica and alumina abrasive particles are presented. The polish rates with alumina slurries vary in accordance with the hardness of the material being polished, suggesting a dominant role for a wear mechanism. However, polish rates with silica slurries do not relate directly to the hardness of the film, indicating a more complex removal mechanism.
Optical Characterization of Porous Membranes
Authors: Mujat Claudia , Denney Lorrene , Dogariu Aristide 
Published: April 2011

ABSTRACTMultiple light scattering techniques are intensively investigated as potential characterization tools for a broad range of applications. We are reporting on the noninvasive characterization of filters used in processes such as slurries filtering for CMP.Filters are soft porous membranes characterized by their pore size distribution and thickness, and a noncontact, nondestructive optical procedure to measure these properties is highly desirable. Due to their internal inhomogeneity, porous media strongly scatter light and, therefore, a specific procedure needs to be developed.In this work, low coherence interferometry is used to investigate light propagation in the filter and obtain the reflectivity as a function of optical pathlength for backscattered photons. This can be subsequently related to the optical properties of the sample using analytical and/or numerical models, and the porosity of the sample can be determined. In the case of filters with thicknesses much larger than the wavelength, a diffusion approximation for light propagation is used to infer the porosity information. For thinner membranes, numerical methods are used to describe the intermediate low-scattering regime that can not be represented analytically. As a direct result of the measurement, the thickness of the filter is determined independent of porosity.
Dynamic Mechanical Analysis (DMA) of CMP pad materials
Authors: Li Irene , Forsthoefel Kersten M. , Richardson Kathleen A. , Obeng Yaw S. , Easter William G. , Maury Alvaro 
Published: April 2011

ABSTRACTIn the semiconductor industry, there is a need to establish fundamental, mechanism-based, correlation(s) between process conditions, consumables (e.g., pads and slurries), and observed process performance in Chemical-Mechanical Polishing (CMP). In this paper, we present recent results of studies on polyurethane-based CMP pads in static and dynamic conditions using Dynamic Mechanical Analysis (DMA) to monitor modulus and energy damping changes. Two-layered, composite IC1000 on Suba IV pads, [IC1000 (cast and cured polyurethane elastomer) / Suba IV (polyurethane impregnated polyester felt)], were analyzed: prior to use (fresh); after a 24-hr soak in silica-containing oxide slurry (basic); and after oxide polishing (used). Upon comparison it was observed that a characteristic transition feature due to water is present at sub-ambient temperatures in both the slurry soaked and used pads. Exposure of as-received pads to basic oxide slurry results in a broad, high temperature transition thought to be the result of chemical-induced disruption of macrostructural units. Polishing (load-enhanced chemical exposure) introduces further changes to the polymer network represented by an apparent degradation to the structural species responsible for the high temperature transition in Suba IV.
An Evaluation of the Effects of Benzotriazole in NH4OH Slurry for Copper CMP
Authors: Len V.S.C. , Mcneill D.W. , Gamble H.S. 
Published: April 2011

ABSTRACTChemical mechanical polishing (CMP) of copper using alumina-based NH4OH slurry containing benzotriazole (BTA) has been evaluated in terms of polish efficiency and viability. Dishing of damascene copper patterns can result from a combination of chemical dissolution and mechanical abrasion due to the deformed polishing pad bending into the recessed copper regions. The addition of at least 0.1 wt.% BTA to the slurry leads to the formation of a thin Cu(I)-BTA polymer on the copper surface during CMP. This polymer reduces the amount of dishing by an order of magnitude. At the same time, however, the CMP polish rate falls sharply with the addition of 0.1 - 0.25 wt.% BTA to the slurry. Above 0.25 wt.% BTA, the polish rate falls no further. Stability of alumina particles in the NH4OH slurry is found to deteriorate with the addition of BTA. Integrated copper/barrier electromigration resistance test structures with large contact areas (2×2mm) have been successfully patterned using a 2-step CMP/etching process scheme, using a BTA-containing slurry to minimise dishing.
Fundamental Study of Iodate and Iodine Based Slurries for Copper CMP
Authors: Lee Seung-Mahn , Mahajan Uday , Chen Zhan , Singh Rajiv K. 
Published: April 2011

ABSTRACTThe chemical mechanical polishing of copper in several slurry chemistries based on iodate and iodine oxidizers has been investigated. Benzotriazole (BTA) and potassium iodide (KI) were used for preparing the polishing slurry chemistries based iodate. As observed by the anodic electrochemical behavior of copper and the surface analyses of EDS, it was determined that CuI layer formed in the iodate and iodine based solutions. Especially, in I2 slurry in pH 4, CuI layer formed very fast and uniformly, and passivated the copper. In addition, the highest removal rate using this slurry was obtained. These results were compared to H2O2 based slurries. From these experimental results, the slurry containing 0.1M KIO3 and 0.01M KI, and 0.01N I2 give better results than H2O2 based slurry in copper CMP.
Planarization of Copper Damascene Interconnects by Spin-Etch Process: A Chemical Approach
Authors: Mukherjee Shyama P. , Levert Joseph A. , DeBear Donald S. 
Published: April 2011

ABSTRACTThe present work describes the process principles of “Spin-Etch Planarization” (SEP), an emerging method of planarization of dual damascene copper interconnects. The process involves a uniform removal of copper and the planarization of surface topography of copper interconnects by dispensing abrasive free etchants to a rotating wafer. The primary process parameters comprise of (a) Physics and chemistry of etchants, and (b) Nature of fluid flow on a spinning wafer. It is evident, that unlike conventional chemical-mechanical planarization, which has a large number of variables due to the presence of pads, normal load, and abrasives, SEP has a smaller number of process parameters and most of them are primary in nature. Based on our preliminary works, we have presented the basic technical parameters that contribute to the process and satisfy the basic requirements of planarization such as (a) Uniformity of removal (b) Removal rate (c) Degree of Planarization (d) Selectivity. The anticipated advantages and some inherent limitations are discussed in the context of process principles. We believe that when fully developed, SEP will be a simple, predictable and controllable process.
Structural Characterization of Epitaxial GMR Magnetic Multilayers and Spin Valves Grown by Sputter Deposition
Authors: Geng H. , Loloee R. , Heckman J.W. , Bass J. , Pratt W.P. , Crimp M.A. 
Published: April 2011

ABSTRACTEpitaxial Cu/Py/FeMn and (Cu/Co)×20 GMR magnetic multilayers were grown on single crystal (011) Nb that was deposited on (1121) Al2O3 substrates by dc magnetron sputtering. Electron backscatter patterns (EBSPs) revealed that the Cu films display two twin variants, corresponding to two stacking sequences of {111} planes in fcc. The epitaxial orientation relationship between the bcc Nb and both fcc Cu variants was the Nishiyama-Wasserman (N-W) relationship. Conventional TEM observations revealed epitaxial growth for both the Cu/Py/FeMn and (Cu/Co)×20 multilayers. High-resolution TEM confirmed epitaxial growth of close packed (011) Nb on (1120) Al2O3 substrates with [111]Nb∥[0001]Al2O3. Numerous small twins were observed in the Cu near the Cu-Nb interface of the Cu/Py/FeMn multilayer. In the Cu/Co multilayer, the growth planes of the Cu and Co were found to be {100} instead of the expected close-packed {111} planes of the fcc structure.
First Principles Based Solution to the Boltzmann Transport Equation for Co/Cu/Co Spin Valves
Authors: Maclaren J.M. , Malkinski L. , Wang J.Q. 
Published: April 2011

ABSTRACTWe present the results of a first principles based semi-classical study of electronic transport in Co/C/u/Co spin valves. The model is parameterized using Bloch states obtained from local spin-density electronic structure calculations and lifetimes appropriate to sputtered films. The approach is used to study the variation in giant magnetoresistance (GMR) with the individual layer thicknesses. Using values for the lifetimes for electrons in the Co and Cu layers that reproduce the resistivities of sputtered films, we are able to rationalize the variation in the current in the plane (CIP) GMR in a set of Co/Cu/Co spin valves produced under similar conditions. Important contributions to the GMR come from two sources, a channeling effect in the Cu which is a direct result of the different sized Fermi spheres for majority Cu and Co electrons, and from within a region in the Co layers within about one to two mean free paths of the interface. Unlike the CIP GMR, values for the current perpendicular to the plane (CPP) GMR are much larger and much less sensitive the variations in the individual layer thicknesses.
Large Anisotropy Via Oblique Sputtering of Ta Underlayers
Authors: Bonevich J.E. , McMichael R.D. , Lee C.G. , Chen P.J. , Miller W. , Egelhoff W.F. 
Published: April 2011

ABSTRACTAnisotropy fields in excesss of 120kA/m(1500Oe)have been produced in 3 nm to 5 nm thick polycrystalline films of Co with Ta underlayers. The unusualy high anisotropy is magnetostatic in origin, and is induced by corrugations on the surface of an obliquely sputtered Ta underlayer. Cross-sectional TEM reveas 8 nm columnar grains of Ta tilted toward the Ta source and elongated perpendicuar to the Ta flux in the film plane. The anisotropy field of the Co film increases with both the underlayer thickness and the angle between theTa source and the film normal. In spin valve samples, the anisotropy is attenuated by more than an order of magnitude across a 4nm thick Cu spacer. Magnetoresistance measurements on a spin valve indicate less than 2° dispersion in hard axis directions, and despite the nanometer-scale roughness of the underlayer, there is weak broadening of the ferromagnetic resonance line.
In situ electrical resistance measurements of Al-Ge films in the TEM using a modified heating holder
Authors: Verheijen M.A. , Donkers J.J.T.M. , Thomassen J.F.P. , van den Broek J.J. , van der Rijt R.A.F. , Dona M.J.J. , Smit C.M. 
Published: April 2011

ABSTRACTA TEM specimen holder has been developed for the measurement of the electrical resistance of a TEM sample as a function of temperature. A Philips TEM heating holder was modified for this purpose. This creates the opportunity to directly correlate changes in the resistance to microstructural changes as a function of temperature.The microstructure of Al-Ge films of several thicknesses has been studied in an in-situ annealing experiment and has been recorded on videotape, while simultaneously acquiring resistance data. These in-situ TEM studies confirm that the irreversible decrease in resistance of these films is caused by crystallisation. During this transition segregation occurs, resulting in crystalline Al and Ge phases.
Characterization of Cu-Al alloy/SiO2 interface microstructure
Authors: Wang Pei-I , Murarka S. P. , Yang G.-R. , Barnat E. , Lu T.-M. , Chen Y.-C. , Li Xiang , Rajan K. 
Published: April 2011

ABSTRACTCu-Al alloys have been recommended for application as the diffusion barriers/adhesion promoters for advanced copper based metallization schemes. This approach to barrier formation is to generate an ultra-thin interfacial layer through Cu alloying without significantly affecting the resistivity of Cu. In this paper the microstructure of the bilayers of Cu/Cu-5 at%Al and Cu-5 at%Al/Cu sputter deposited on SiO2 before and after thermal annealing is investigated by transmission electron microscopy (TEM). Interfacial layer is observed in both cases. The variation of the resistance of the Cu-Al alloy film is consistent with its microstructure. The x-ray diffraction (XRD) spectra of Cu-5 at%Al on SiO2 shows that the addition of Al into Cu intends to favor the Cu (111) texture. These results will be presented and discussed showing that films of Cu doped with Al appear to act as a suitable barrier and adhesion promoter between SiO2 and Cu.
In Situ Curvature and Diffraction Studies of Pd Films on Si(001) During Solid-State Reaction
Authors: Gergaud P. , Thomas O. , Chenevier B. , Ghetta V. , Mouroux A. , Zhang S.L. 
Published: April 2011

ABSTRACTThe stress evolution during silicide formation from thin metal films on Si substrates is not well understood. It requires a detailed knowledge of the mechanical properties of each substance, i.e. metal, silicide(s) and Si, in the reacting system. In situ curvature measurement generally gives access to the overall force in the layered stack, whereas in situ X-ray diffraction (XRD) provides information about the mechanical strain in each crystalline sublayer. In this study, we performed both in situ XRD and curvature measurements on the Pd/Si(001) system. From both measurements, we found out that the in-plane strain in the metal and in the silicide is compressive. Whereas it decreases all along the solid-state reaction for the silicide, it slightly increases for the metal. We then compared our results with the qualitative model proposed by Zhang and d'Heurle. This model suggests a high compressive stress in the silicide at the very first stage of the reaction. This is in good agreement with our experimental results. Finally, the measured strains were then translated into force per unit width and compared to in-situ curvature measurement results. A good qualitative agreement between these two different measurements was also found.
Ab Initio Studies of AlSb (001) Adatom Behavior and Reconstruction
Authors: Modine N. A. , Kim Hanchul , Kaxiras E. 
Published: April 2011

ABSTRACTWe discuss a recent investigation of adatom behavior on the AlSb(001) surface using first-principles electronic structure methods based on the density functional theory. For Al and Sb adatoms, we find a number of novel adatom structures that differ dramatically from previous results for the superficially similar group-III arsenides. In particular, we conclude that it is energetically favorable for an Al adatom to incorporate substitutionally into the outermost layer of the AlSb surface. This observation helps motivate a proposed new reconstruction for the AlSb(001) surface. Finally, we argue that the unusual adatom behavior identified for this surface probably results from the presence of a dimer row composed of a double layer of group-V atoms in the reconstruction, and therefore, it should be generic to all of the antimonides, as well as, the c(4 × 4) reconstruction of the arsenides and phosphides.
Formation and Evolution of InAs Nanowires on an InP(001) Surface
Authors: Yang Haeyeon , Smathers J. B. , Ballet P. , Workman C. L. , Salamo G. J. 
Published: April 2011

ABSTRACTWe have used in-situ scanning tunneling microscopy (STM) to study the formation and evolution of InAs islands on an InP (001) surface. The InAs islands are produced by (i) exchange of P-atoms with As-atoms or by (ii) direct deposition of In and As. In both cases InAs nanowires arem elongated along the [ī 10] direction with a length over 1 µm. We observe these nanowires to be stable under an arsenic environment while unstable with no arsenic flux, and eventually transform into a rectangular-based pyramid with a truncated top. These observations indicate that surface reconstruction can play a role in the selection of quantum wire or dot growth.
Effects of the Dislocation Density and Surface Energy on Phase Diagrams of the S-K Growth Mode for the GaInN/GaN and GaPSb/GaP Systems
Authors: Nakajima K. , Ujihara T. , Miyashita S. , Sazaki G. 
Published: April 2011

ABSTRACTThe growth of thin films has been categorized into three types namely the Frank-van der Merwe (FM) mode, the Stranski-Krastanov (SK) mode, and the Volmer-Weber (VW) mode. The strain, surface, and interfacial energies were calculated for the three types of growth mode of the GaInN/GaN and GaPSb/GaP systems by considering the effects of the dislocation density and reconstruction of dangling bonds. The phase diagrams of the growth modes were determined for the GaInN/GaN and GaPSb/GaP systems. In the GaInN/GaN system, the VW mode appears in the most region of the phase diagram. The region of the VW mode becomes smaller as the dislocation density increases. In the GaPSb/GaP system, the SK and VW modes appear and the region of these modes becomes larger as the reconstruction ratio increases
Movpe Strip-Like Self-Organization of InAs Grown on InP Vicinal Surfaces
Authors: Auvray Laurent , Soulière Véronique , Dumont Hervé , Dazord Jacques , Monteil Yves , Bouix Jean 
Published: April 2011

ABSTRACTWe have investigated the influence of MOVPE growth parameters on the surface morphology of InAs nanostructures grown on 0.2° misoriented (001)InP substrates. Thin layers of nominal thickness of about 3 and 6 ML were deposited at 500°C with V/Ill flux ratios ranging from 50 to 240. The samples were cool down from 500 to 350°C during 6 minutes under either arsine or phophine atmosphere. The influence of this step has been found to greatly determine the surface morphology of the nanostructures observed by atomic force microscopy. Dots self-aligned along the steps and forming a non continuous strip, regularly spaced every 3-4 terraces have been obtained. The morphology of the strips can be varied with the growth conditions (V/III flux ratio). In this work, we will propose a mechanism for the formation of the strips observed during the cooling under phosphine atmosphere taking into account an As » P exchange.
Step Bunching, Chemical Ordering, and Diffusivity in Si1−yCy Heteroepitaxy
Authors: Grosse Frank , Croke Edward T. , Gyureb Mark F. , Floydc Margaret , Smith David J. 
Published: April 2011

ABSTRACTThe growth of Si1−yCy on Si(001) and Si(118) surfaces is investigated experimentally and theoretically. A step instability is found on (118) surfaces leading to step bunching, under low C-concentrations. This behavior is explained by increased diffusivity of Si dimers in the vicinity of carbon. Self adjusting step bunches are found in kinetic Monte Carlo simulations with ordering of the carbon along nearly (001) planes. Experimental parameters (i.e., temperature, flux rate, and tilt angle of the substrate), which are controllable experimentally, can be used to adjust the length scale of the step bunching.
The Growth of High Quality GaAs Epilayers on Stripe Patterned InP Substrates With a Transferred GaAs Fused Layer
Authors: Hwang Sung Min , Park Young Ju , Kim Eun Kyu , Choi In-Hoon 
Published: April 2011

ABSTRACTBoth the wafer fusion and the heteroepitaxy technology were used successfully to obtain high quality GaAs layer on the InP substrate where the lattice mismatch was 3.7 %. The enhancement of the lateral growth rate was a crucial factor for the formation of high quality QWR in the patterned fusion layer. This technique can provide a way of overcoming the limitation of heteroepitaxy caused by misfit problems and its subsequent quality degradation. It is expected that the overgrowth technique on the patterned fusion layer can be applicable to the photonic device fabrication on the other substrate such as Si.
2-D Precursors and Interdiffusion in CdSe/ZnSe Self-Assembled Quantum Dots
Authors: Dobrowolska M. 
Published: April 2011

ABSTRACTThis paper discusses structural and optical data taken on a series of MBE grown samples where n monolayers of CdSe (0.5< n < 2.6) was deposited on (and subsequently capped by) ZnSe. The cross-sectional scanning transmission electron microscopy (STEM) images observed on samples with lowest CdSe coverages reveal the co-existence of 2D ZnCdSe platelets and 3D islands, showing clearly that the platelets act as precursors for the formation of the 3D islands. The STEM data also present direct graphic evidence that interdiffusion plays an important role in the dynamics of CdSe quantum dot formation. The macro- and micro-photoluminescence results fully confirm the STEM data. For coverages below 1.5 monolayers, photoluminescence data show only the emission characteristic of 2D platelets, while for coverages between 1.5 and 1.9 monolayers simultaneous emissions from 2D and 3D islands are observed. The sample obtained by depositing the highest (2.6 monolayer) CdSe coverage shows only the emission characteristic of 3D islands.
In Situ Real-Time Studies of Oxygen Incorporation in Complex Oxide Thin Films Using Spectroscopic Ellipsometry and Ion Scattering and Recoil Spectrometry
Authors: Mueller A.H. , Gao Y. , Irene E.A. , Auciello O. , Krauss A.R. , Schultz J.A. 
Published: April 2011

ABSTRACTThe surface termination of c-axis oriented YBa2Cu3O7-δ (YBCO) and the oxygen incorporation mechanism has been investigated using a unique combination of spectroscopic ellipsometry (SE) and time of flight ion scattering and recoil spectrometry (ToF-ISARS). The high surface sensitivity of the ToF-ISARS technique combined with the bulk oxygen sensitivity of SE are shown to yield complimentary information. The SE provided the film orientation and quality, while ToF-ISARS supplied surface compositional and structural information and enabled isotopic 18O tracer studies. It was determined that the 0 content of the film had little effect on the surface termination of the film, indicating a lack of labile Cu(l) sites at the c-axis oriented YBCO surface. Also, strong evidence for a Ba or BaO terminated structure is shown. The data related to the 18O tracer studies indicate that O from the reaction ambient incorporates only into the labile Cu(1) sites during both deposition and annealing, while stable O sites were populated with O from the sputtered target, indicating either the need for sputtered atomic O or sputtered YCuO complexes to occupy the stable Cu(2) sites.
Reactive Cluster Epitaxy: CoSi2 Nanoparticles on (111) Si
Authors: Zimmermann C.G. , Yeadon M. , Kleinschmit M. , Averback R.S. , Gibson J.M. 
Published: April 2011

ABSTRACTThe formation of epitaxial CoSi2 islands of nanoscopic dimensions is reported using the technique of reactive cluster deposition. Co clusters in the size range 5-50nm were synthesized by sputtering a high purity Co target inside a UHV sputtering chamber. The clusters were then deposited on the reconstructed Si (111) surface. Upon annealing the particles reacted with the Si substrate to form epitaxial CoSi2.Our observations were made using a JEOL 200CX transmission electron microscope modified for in-situ sputtering and ultrahigh vacuum conditions.