bluuebunny/crossref_metadata_2025 huggingface dataset:
Kelvin Test Structure Modeling of Metal-Silicide-Silicon Contacts
Authors: Reeves G. K. , Holland A. S. , Leech P. W.
Published: April 2011

Low resistance ohmic contacts for silicon devices commonly incorporate silicide materials as part of the contact. The electrical characterisation of ohmic contacts requires the use of various test structures such as the Cross Kelvin Resistor in order to determine the specific contact resistance ρc. This paper describes the results of using a three-dimensional finite element model of a Kelvin Resistor test structure in order to determine the influence of the electrical and geometrical parameters of a silicide-well on the magnitude of ρc. The same model of the test structure is further used to model the current density in the contact region. The results indicate that the presence of a silicide-well leads to reduced values of both ρc and the current density.
The Influence of Capping Layer Type on Cobalt Salicide Formation in Films and Narrow Lines
Authors: Besser P. R. , Lauwers A. , Roelandts N. , Maex K. , Blum W. , Alvis R. , Stucchi M. , Potter M. De
Published: April 2011

The effect of capping layer (Ti vs TiN) on CoSi formation and CoSi2 sheet resistance has been investigated. Resistance measurements and XTEM analysis have been used to show that the Ti cap lowers the activation energy for CoSi formation by gettering the O2 from the RTA (rapid thermal anneal) ambient and eliminating the formation of SiO2 between the growing CoSi and the Co. The sheet resistance of cobalt silicide formed from Co/Ti and Co/TiN bilayers on poly- Si lines was measured as a function of linewidth and RTA temperature. With a Ti cap, the sheet resistance is low and independent of temperature, and the RTA process window is large.
Doping Influence on TiSi2 C49-C54 Phase Conversion Kinetics by Micro-Raman Spectroscopy
Authors: Meinardi F. , Quilici S. , Moro L. , Queirolo G. , Sabbadini A.
Published: April 2011

MicroRaman measurements on titanium silicide films grown on single-crystal and polycrystalline silicon substrates doped with As, BF2 and P have been performed. The data collected on patterns of different areas and shapes, but comparable doping level show that the doping has negligible effects both on C54 nucleation center density and on activation energy for the C49/C54 phase transition. On the contrary, substrate strongly affects the C54 growth rate, ruling the ability of the C54 phase to propagate after the nucleation.
Diffusion Barrier Properties of the Tin Films Prepared by Ecr Pecvd Method
Authors: Park Hye-Lyun , Jang Seong-Soo , Lee Won-Jong
Published: April 2011

TiN film is used as a diffusion barrier layer in contact and via holes in the metallization process of the microelectronics. In most cases, TiN film has been prepared by sputtering which has limited conformality. With the shrinkage of the dimension of the device structure there has been an urgent request for new deposition methods which offer better conformality. Recently, modified PVD systems like highly ionized sputtering system and CVD systems like MOCVD and PECVD systems have been developed.

We prepared TiN films with TIC4, N2, and H2 in an ECR PECVD system. TiN films prepared at the temperature of 450°C had resistiveity lower than 50 μm Ω cm and better step coverage than those prepared by PVD system. Barrier properties of the TiN films against Cu were investigated and related with the film properties like composition and microstructure.

The Cu/TiN/Si structure were annealed in an H2/Ar atmosphere for 30 min at the temperature range from 500 to 600°C.

Plasma treatment and thermal treatment during and/or after the deposition in various atmosphere were adopted to change the composition and the microstructure of the TiN films.

The composition of the film was analyzed with AES, the microstructure of the film was observed with SEM and the crystallinity was analyzed with XRD. The electrical resistivity was measured with four-point probe method. Barrier properties of the films were studied again Cu metallization. The change in the resistivity and the structure of the Cu/TiN/Si were investigated after the heat-treatment.
Asymmetrical Heating Behavior at Ni/Doped-Si Junctions for Soi Structures
Authors: Liao C. N. , Tu K. N.
Published: April 2011

With an increasing component density and shrinking feature size in integrated circuit (IC) chips, the heat dissipation issue on the IC chips becomes increasingly important because of device performance and reliability concerns. The heating behavior at Ni/doped-Si junctions, which depends on Joule heating, Peltier effect and heat conduction, is explored in the study. A semiconductor-on-insulator (SOI) structure is used to obtain thermal isolation of the test specimen. The Si channel of 720 μm × 25 μm was lithographically defined and implanted with As+ and BF2+ dopants at a dose of 5×1015 ions/cm2, respectively. By applying a current through a Ni contact/doped-Si/Ni contact structure and measuring the resistance of the doped Si channel near the cathode and the anode ends, we found an obvious asymmetrical heating behavior at the two ends, depending on the dopant type and post-implanatation annealing condition. The Seebeck coefficients of doped Si were measured to be about 140 μV/K and 80 μV/K for BF2+ - doped Si and As+-doped Si, respectively.
Processing of Pure Ni Mocvd Films
Authors: Brissonneau Laurent , Reynes Alex , Vahlas Constantin
Published: April 2011

In this study are reported results on the processing of nickel thin films by metal-organic chemical vapor deposition starting from nickelocene, at atmospheric and reduced pressures, and at temperatures varying between 150 °C and 300 °C. Films present a Volmer-Weber type nodular morphology. Nodules are composed of small crystallites, the mean size of which is about 50 nm. Carbon (up to 10 at. % depending on processing conditions) is incorporated at interstitial rather than intergranular position in the films. High operating pressure favors carbonfree films. An analysis of the gas phase reaction by mass spectrometry is presented in order to understand the mechanisms of the carbon contamination of the deposits.
The Best Way to Obtain Good Quality CVD-TiN Films from TiCl4 and NH3
Authors: Hamamura Hirotaka , Shimogaki Yukihiro , Akiyama Yasunobu , Egashira Yasuyuki , Komiyama Hiroshi
Published: April 2011

TiN films deposited by CVD utilizing TiCl4 and NH3 are widely used in ULSI processes. The residual chlorine in the film is one of the major issues of TiCl4 based chemistry [1–5]. We have examined the kinetics of TiN-CVD using TiCl4 and NH3 as precursors to determine method for controlling the residual chlorine concentration.

We analyzed the deposition rate profiles obtained from a simple tubular isothermal reactor. Deposition was performed over the temperature range from 300°C to 500°C and with varying initial concentrations of TiCl4 and NH3. We found that the deposition rate was independent of the TiCl4 concentration at higher concentrations. The deposition rate was proportional to the TiCl4 concentration in the low concentration range. This phenomenon can be well explained by a Langmuir-Hinshelwood type mechanism. Examination of the deposition rate dependence on the concentration of NH3 showed that both the maximum deposition rate at high TiCl4 concentrations and the first order kinetic rate constant in the lower TiCl4 concentration range were proportional to the NH3 concentration. These results indicate that the deposition was controlled by the Eley-Rideal mechanism. The residual chlorine concentration was found to be proportional to the surface coverage factor of adsorbed TiCl4. We conclude that the best way to obtain good quality TiN films can be obtained theoretically through these kinetic studies.
Scaling and Integration of High Performance Interconnects
Authors: Yang Simon
Published: April 2011

Interconnect delay is believed to have a dominating impact on the speed of large logic circuits (such as micro-processors) when the Si technology is scaled into sub- 0.25um generations. In this paper, we analyzed interconnect scaling issues based on leading micro-processor trend data, simple RC delay model and the “Rents' rule”. It was concluded that, in order to not limit the speed of large logic circuits, “fat” metal wires need to be used for upper metal layers, which will lead to a rapid increase of required number of metal layers (>10) for sub-0.25um technology generations. Introducing Cu and low ε interconnect system can delay this rapid increase by ∼1 generation. Creating multiple clock frequencies in large logic chips and reducing the size of high frequency islands appears effective in containing the interconnection delay problem. Therefore, the proposed interconnection scaling/development strategy is to introduce Cu and low ε dielectric into manufacturing in next 1∼3 generation (0.25um∼0.13um), develop low cost and high yield interconnect system to enable ∼10 interconnect layers, and improve circuit design methodology to reduce high frequency island size.
Thermomechanical Behavior of Continuous and Patterned Al Thin Films
Authors: Kraft O. , Nix W.D.
Published: April 2011

In this paper, we study the influence of the line width on the mechanical behavior of narrow unpassivated lines of pure Al and Al with 0.5 wt.-% Cu. The stress/temperature behavior during thermal cycling is investigated using x-ray diffractometry. Our results suggest that it is possible to distinguish between two temperature regimes in which different deformation mechanisms take place. At low temperatures, the narrowest lines sustain larger stresses than the continuous films, whereas at high temperatures the opposite behavior was found. Further, iso-thermal stress relaxation measurements on pure Al lines after various heat treatments were performed. These results indicate the existence of a threshold stress below which no deformation of the lines occurs.
The Stress Change in Passivated Al Lines Due to the Reaction Between Ti and Al
Authors: Marieb T. , Mack A. , Lee J. , Dibattista M.
Published: April 2011

The thin film reaction between Ti and Al-0.5%Cu to form TiAl3 is common in the microelectronics industry. In this paper the stress changes in Al-0.5%Cu films at elevated temperatures during the reaction are measured. The changes are measured in blanket films as well as in passivated interconnect lines. Results show that in blanket films the Al-0.5%Cu does not experience any stress change due to the reaction. However in passivated lines, where the layers are not allowed to relax in the normal direction, tensile stresses build up in the Al-0.5%Cu due to the volume shrinkage that happens when these films react.
FEM Analysis of Thermal Stresses in Advanced Electronic Packages
Authors: Rzepka Sven , Korhonen Matt A. , Li Che-Yu , Meusel Ekkehard
Published: April 2011

Following the general tendency of downsizing in microelectronic packages, the interposing layer between silicon chip and organic board is constantly reduced while the differences in thermal expansion stay constant. Consequently, thermal stresses have become the most important reliability concern in advanced packages. Finite element analysis is known as an effective way of theoretically studying the mechanical situation in multi-component systems with complex material behavior. The paper presents results of finite element simulations that provide practical guidance for design, process and material developments of chip size packaging (CSP), flip chip (FC), and direct chip attach (DCA) modules. Using realistic and efficient models, a low-cost CSP concept is assessed, the effects of underfill, underfill imperfections, and underfill defects on the reliability of FC modules are studied, and an optimum set of mechanical properties for underfill materials is proposed. Finally, reliability risk factors in DCA modules are identified and preliminary design guidelines are given.
Novel Electromigration Failure Mechanism for Aluminium-Based Metallization on Titanium Substrate
Authors: Girardi G. , Caprile C. , Cazzaniga F. , Riva L.
Published: April 2011

In this paper a phenomenological characterisation of an anomalous grain growth, observed after classical electromigration lifetests, on Al-l%Si-0.5%Cu multigrain stripes, deposited at high temperature (460°C) on a Ti substrate, is reported. Failure analysis, carried out by Scanning Electron Microscopy (SEM) and Focus Ion Beam (FIB), has detected an abnormal single-grain growth in the vertical direction, starting from the Ti/Al interface. Medium Time to Failure (MTF) data are compared with those of stripes on Ti/TiN substrate, on which no grain growth was observed. The growth of the anomalous grains has been related to the Ti/Al interface properties. Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM) analyses concurrently show a higher texture of the film on the Ti, compared with the film on the Ti/TiN substrate. The tight columnar orientation of grain boundaries strongly limits the mechanism of grain boundary diffusion during electromigration stress. The atomic flux is then forced to take place at the Ti/Al interface, where the epitaxial growth of the Al single grains is favoured.
Statistical Evaluation of Stressmigration Reliability in Al-Cu Interconnects
Authors: Jawarani D. , Gall M. , Capasso C. , Müller J. , Hernandez R. , Kawasaki H.
Published: April 2011

High-resolution resistance measurements of metal stripes have been performed to study void growth duringin situannealing at 180°C. Void growth has been characterized by resistance monitoring over 14,000 hours. During the annealing of Al-lwt%Cu stripes, Cu atoms from solution migrate to grain boundaries to form Al2Cu precipitates leading to a drop in resistance. At the same time, relaxation of tensile stresses in metal stripes takes place in the form of void nucleation and growth, leading to an increase in resistance. The resistance drop due to precipitation was shown to obey Avrami's precipitation kinetics while void growth over this time period obeyed a diffusion-type equation. The resulting equation to describe this physical model was fitted to the measured resistance data. Extrapolation to failure condition (ΔR/R=10%) could therefore be obtained for all the devices under test and plotted on a cumulative probability plot. Using the measured value of activation energy for void growth, stressmigration reliability was then assessed by extrapolation to an operating temperature. Post-mortem microscopy was performed to correlate resistance increase with void density and size in these interconnects. Finite element simulations were performed to calculate resistance increases due to voiding in metal stripes and correlate these with the experimentally obtained data.
A Quantitative Study of Void Nucleation Times in Passivated Aluminum Interconnects
Authors: Doan Jonathan C. , Bravman John C. , Flinn Paul A. , Marieb Thomas N.
Published: April 2011

Accelerated electromigration tests were performed in a High Voltage SEM (HVSEM). These experiments were conducted on 10 identical, passivated Al interconnect test structures at a temperature of 237°C and a current density of 30mA/µm2. Simultaneous testing and observation of the entire structure allowed the void nucleation times to be measured. Two normal distributions fit the nucleation times. The second of these distributions coincides roughly with the distribution of failure times of the test structures. Fracture of the passivation is hypothesized as the mechanism that causes the concurrent late nucleation and failure processes.
Electromigration-Induced Drift in Damascene vs. Conventional Interconnects: An Intrinsic Difference
Authors: Proost J. , Samajdar I. , Witvrouw A. , Maexo K.
Published: April 2011

The electromigration (EM) behaviour of damascene Al(Cu)-interconnects has been studied for the first time by drift experiments and results directly compared to plasma-etched lines. For the latter EM is known to occur through sequential stages : an incubation period, needed for Cu-depletion, and an Al-drift stage. It is shown that using a damascene implementation, the incubation time significantly increases but the Al-drift velocity does as well. This is demonstrated to be an intrinsic effect, directly related to the technological nature of both metallization schemes. Implications on lifetime prediction at operating conditions are discussed.
Evolution of the Electrical Properties of Interconnects Under Electromigration Stress
Authors: Jones B.K. , Guo Jianping , Xu Yanzhong , Trefan G.
Published: April 2011

We report experimental results of measurements of the changes in the resistance and thermal non-linearity of a variety of samples during accelerated electromigration stress to failure. The value of the extra measurement of the second harmonic of the AC bridge signal is illustrated by observations of changes in the thermal conductance to the substrate and the temperature coefficient of resistivity which are not detected by the resistance measurement. These quantities are also larger than the resistance measurement.
Test Methods for Characterizing Piezoelectric Thin Films
Authors: von Preissig F. J. , Zeng H. , Kim E. S.
Published: April 2011

Two experimental techniques for quantifying MEMS-relevant material constants of piezoelectric thin films are presented. The first is an improved version of our recently developed ‘plank method.’ This technique is used to determine the product of the biaxial elastic modulus and the piezoelectric constant d31. The updated method is easier and more precise, and it utilizes the results of dynamic as well as improved static finite-element analyses. The second method is the bulge test, here emphasizing the special requirements of piezoelectric and fragile films. Results from both techniques applied to zinc oxide are presented.
The Fracture Toughness of Polysilicon Microdevices
Authors: Ballarini R. , Mullen R.L. , Kahn H. , Heuer A.H.
Published: April 2011

The development of polysilicon fracture mechanics specimens with characteristic dimensions comparable to those of typical microelectromechanical systems (MEMS) devices is presented. The notched cantilever specimens are fully integrated with a simultaneously microfabricated electrostatic actuator, which allows on-chip testing of the specimens without the need of an external loading device, and without any possible influences from external sources. Under monotonic loading, the average maximum tensile stress (strength) and average nominal fracture toughness were measured as 4.2 GPa and 3.5 MPa-m½ for boron-doped specimens, and 5.0 GPa and 4.0 MPa-m½ for undoped specimens. An average modulus of rupture of 3.3 GPa and average nominal toughness of 2.7 MPa-m½ were measured for specimens cracked under cyclic resonance loading. The differences between the monotonic loading and cyclic loading data are attributed to fatigue initiation of a sharp crack from the 1 ýtm radius notch. The experimental data is consistent with a critical flaw size in the fabricated devices, a, that is related to the fracture toughness Klc by Klc/a1/2=4600 MPa.
Adhesion Promotion by Surface-Modification at the Pmma-Metal Interface for Liga-Type Processing
Authors: Das S. S , Malek C. G.Khan
Published: April 2011

The formation of high aspect ratio Micro-Electro-Mechanical Structures (HI-MEMS) requires good adhesion of the thick microstructures to the substrate. The interfacial bond strength between PMMA and various metal substrates (Ti, Cu, Au, and Ni), in the preliminary stages of the LIGA process, was evaluated by shear stress measurement. Adhesion promotion processes have been investigated such as texturing of the surface of Ti and Cu substrates by chemical oxidation or thermal processing of the PMMA sheet, and use of a positive resist as an interfacial adhesion promoter. Several fold increases in bond strength were obtained, the largest increase associated with a combination of substrate roughening, thermal treatment and use of adhesion promoters.
Mechanical Property Evaluation of Electroplated High Aspect Ratio Microstructures
Authors: Stephens L. S. , Kelly K.W. , Meletis E.I. , Simhadri S.
Published: April 2011

High aspect ratio microstructures (HARMs) with a height of hundreds of micrometers and a width of a few tens of micrometers present high promise in a number of challenging fields. At LSU, a number of applications are being developed in which nickel HARMs are electroplated on metal surfaces (mold insert fabrication for the LIGA process, HARMs on mechanical seal faces, HARMs on heat exchange surfaces, etc.). In some of these applications, the HARMs are subjected to high stresses and the mechanical properties are particularly important. These properties can be used to adjust processing parameters to optimize properties of the HARMS.

This paper presents a method for measuring the strength properties of cantilevered nickel HARMs constructed by LIGA. Experimentally measured values are reported for modulus of rupture (1280 MPa), Young's modulus (153 GPa) and Knoop hardness (500 Hk) for HARMs with an overplated base. SEM micrographs clearly indicate that failure of the beams is brittle and most frequently occurs at the interface of the beam and overplated base.
Fracture Strength of Polycrystalline Silicon
Authors: Jonestt P.T. , Johnsontt G.C. , Howe R.T.
Published: April 2011

A structure has been developed to measure the fracture strength of thin films that allows for a large amount of statistical data to be generated from a single die. The strength of a material is determined by measuring the displacement at fracture of cantilever beams bending in-plane. This device has been used to measure the fracture strain of three different polysilicon materials: polysilicon from two different MCNC MUMPS runs and a polysilicon fabricated at the Microfabrication Laboratory at the University of California at Berkeley. The strain at fracture of the MUMPS polysilicon was measured to be 1.5% ± 0.2% for both MCNC MUMPS runs. The Berkeley polysilicon exhibited a fracture strength of 1.2% ± 0.1%, a difference from the MUMPS result that is statistically significant. Also, no statistical difference in fracture strength was measured on specimens that were super-critically carbon dioxide dried as opposed to furnace dried. In a separate experiment, the Young's modulus of the MCNC MUMPS polysilicon was found to be 173 ± 20 GPa.
Young's Modulus, Yield Strength and Fracture Strength of Microelements Determined by Tensile Testing
Authors: Greek S. , Ericson F.
Published: April 2011

Some mechanical properties of thin film microelements, e.g. fracture strength, depend on the manufacturing process, the load application as well as on size and shape of the microelements. Hence, the test structures that are used to determine mechanical properties should have dimensions of the same order of magnitude as an application structure, i.e. microelements must be used to accurately characterise MEMS. The fabrication of test structures must be realised in the same process as an intended application in order to give accurate results. Microelements are easily viewed in an SEM, but to be handled and tested in situ a micromanipulator was developed. Test structures were designed as released beams fixed to the substrate at one end, with a ring at the other. A high-precision testing unit was mounted on the micromanipulator next to the test structures. In the SEM, the testing unit was manoeuvred to grip the ring of the test structure beam and a tensile test of the beam was then executed. From the test data Young's modulus and fracture strength of polysilicon and single crystalline silicon were evaluated. Relative measurement of test structures with different beam lengths enabled Young's modulus to be evaluated with an accuracy of ±5%. Young's modulus was determined to 172±7 GPa for polysilicon and 142±9 GPa for single crystalline silicon in the <100> direction. The fracture surfaces were examined and compared. Young's modulus, yield strength and fracture strength of microelements made from electroplated nickel and nickel-iron alloy were also measured. Young's modulus was evaluated to 231±12 GPa for nickel and 155±8 GPa for nickel-iron alloy composed of 72 at% nickel and 28 at% iron.
Meso (Intermediate)-Scale Electromechanical Systems for the Measurement and Control of Sagging in LtcC Structures
Authors: Espinoza-Vallejos Patricio , Zhong Jihua , Gongora-Rubio M. , Sola-Laguna Luis , Santiago-Aviles J.J.
Published: April 2011

Sagging of suspended or laminated structures is a common problem in the processing of Low Temperature Co-Fired Ceramics (LTCC). These glass-ceramic composites are susceptible to plastic deformation upon lamination, or under the stress of body forces once the glass transition temperature of the glass binder is reached during processing. We have designed and fabricated, using the conventional methods of LTCC fabrication, meso-scale structures (ranging in size from 100 mm to 1 cm) to quantify and seek control strategies for this problem. We have implemented bridge structures and membranes to emulate most of the conventional structures encountered during packaging or sensor (actuator) device fabrication.

We have observed that when an LTCC tape with holes larger than 400 µm in diameter is laminated, the tapes above and below deform into the cavity. For smaller diameters, deformation is negligible. Bridging structures can be compensated for the potential effect of body forces by screen-printing a thick film over-layer which exert internal tensile stresses on sintering. This can often yield straight bridges. The use of fugitive phase materials, which disappear or flow during firing, is another way of supporting bridging structures. Several of these strategies have been explored, and results are presented.
Bioencapsulation in Sol-Gel Glasses
Authors: Bergogne L. , Fennouh S. , Livage J. , Roux C.
Published: April 2011

Bioencapsulation in sol-gel materials has been widely studied during the past decade. Trapped species appear to retain their bioactivity in the porous silica matrix. Small analytes can diffuse through the pores allowing bioreactions to be performed in-situ, inside the sol-gel glass. A wide range of biomolecules and micro-organisms have been encapsulated. The catalytic activity of enzymes is used for the realization of biosensors or bioreactors. Antibody-antigen recognition has been shown to be feasible within sol-gel matrices. Trapped antibodies bind specifically the corresponding haptens and can be used for the detection of traces of chemicals. Even whole cells are now encapsulated without any alteration of their cellular organization. They can be used for the production of chemicals or as antigens for immunoassays.
Design and Synthesis of Vanadium Pentoxide/Polypyrrole Hybrid Electrochemical Materials
Authors: Harreld J.H. , Dunn B. , Cheng W. , Leroux F. , Nazar L.F.
Published: April 2011

Vanadium oxide/polypyrrole hybrid gels were synthesized by two different strategies. These approaches were focused on either the sequential or consecutive polymerization of the inorganic and organic networks. Both techniques led to monolithic hybrid aerogels. Aerogels synthesized by the consecutive network formation method (“cosynthesis”) with compositions of approximately [PPy]0.8V205intercalated nearly twice as much Li per V2O5(2·8·3·0 Li/V205) as non-hybridized V20, aerogel (1·5 Li/V205). When suitable oxidation and polymerization treatments were applied to the materials, their specific capacity remained reasonably high (180−190 mAh/g compared to 220 mAh/g exhibited by V205, aerogel).
Hybrid Gels and Nanoscale Chemistry for Optical Applications
Authors: Boilot J-P. , Biteau J. , Brun A. , Chaput F. , Morais T. Dantas De , Darracq B. , Gacoin T. , Lahlil K. , Lehn J-M. , Levy Y. , Malier L. , Tsivgoulis G-M.
Published: April 2011

A large variety of materials for optical and optoelectronic applications has been developed by trapping active organic molecules and nanocrystals into pure inorganic and hybrid organic- inorganic gels. Concerning optically active molecules, we focus only here on luminescent materials for solid state tunable lasers and light-emitting diodes, and photochromic materials for integrated optics and optical storage. Optical properties can be controlled by changing the nature and the intensity of chemical and steric interactions between the organic system and the solid host matrix. Concerning nanocrystals, we present two approaches for the synthesis of transparent solids based on 1I-VI semiconducting nanoparticles. A first category of materials consists in the dispersion of CdS nanoparticles in sol-gel silica matrices. The luminescence can be controlled by offering an alternative pathway for the recombination of surface trapped carriers. A second group of transparent materials is obtained by considering the CdS nanoparticles not only as the optically active units, but also as the building blocks for the whole solid.
α-RuCl3: A New Host for Polymer Intercalation. Lamellar Polymer/α-RuCI3 Nanocomposites.
Authors: Wang Lei , Brazis Paul , Rocci Melissa , Kannewurf Carl R. , Kanatzidis Mercouri G. , Claflin B. , Lucovsky G. , Claflin B. , Lucovsky G.
Published: April 2011

α-RuCl3 was identified as a new host for polymer intercalation using different intercalative methods. It is found that Li0.2RuCl3 exfoliates in water into single [RuCl3]x− layers which can be used to encapsulate macromolecules. RuC13/polymer nanocomposites such as Li0.2(PEO)xRuCl3 (PEO=poly[ethylene oxide]), Li0.2(PVP)xRuCl3 (PVP=polyvinylpyrrolidone) and (PPY)xRuCl3 (PPY=polypyrrole) were successfully prepared. (PANI)xRuCl3 (PANI=polyaniline) was prepared by in situ intercalative polymerization directly from α-RuCl3. These nanocomposites were characterized with Thermogravimetric Analysis (TGA), Infrared spectroscopy (IR), Powder X-ray Diffraction (XRD), magnetic measurements, conductivity measurements and thermopower measurements.
Liquid, Methoxylated Polysiloxane / Silica Hybrid Resins by a Non-Hydrolytic Route
Authors: Bourget L. , Mutin P.H. , Vioux A.
Published: April 2011

The preparation of liquid, methoxylated, polysiloxane hybrid resins containing Me2Si(O-)2 (D) or MeHSi(O-)2 (DH) units cross-linked by Si(O-)4 (Q) units was attempted using the nonhydrolytic condensation reaction between Si-Cl and Si-OMe groups, catalyzed by ZrCI4. The structure of the resins was investigated by 29Si NMR, which showed that redistribution reactions played a prominent role. Thus, Si-OMe/Si-OSi redistributions lead to a highly homogeneous, random structure for the D/Q resin. On the other hand, this route does not apply to the synthesis of DH/Q resins, due to the redistribution of Si-H bonds which leads to the escape of MeSiH3 and to the formation of T and TH units.
Shape-Controlled Synthesis of Hydroxyapatite in Organic Media
Authors: Sakamoto K. , Nakahira A. , Okazaki M. , Ichihara J. , Inoue M. , Yamaguchi S.
Published: April 2011

We have examined the effect of organic solvent on the microstructures of hydroxyapatite (HAp) formed by hydrolysis of α -tricalcium phosphate ( α -TCP) in heterogeneous solvent system (water-hydrophobic organic solvent). The shape of HAp was like ultrafine whisker (length : about 1 ∼- 4 µ m) and its size depended on the used organic solvent.

As a simple hybridization, incorporation of fluoride anion (F−) into HAp was attempted in similar system to obtain fluoridated apatite [Ca10(PO4)6(OH)2−x Fx.]. The formation rate was strongly affected by the concentration of F− and reaction temperature. Although the product in water (in the absence of organic solvent) consists of fine particles less than 1 µ m, the product prepared in the heterogeneous solvent system was mixture of ultrafine particles ( ∼ 0.1 µ m) and needle-like particles (length : about 1 ∼ 4 µ m, width : ∼ 0.5 µ m). The microstructures of HAp and FHAp were controlled by hydrophobicity of organic solvent.
Synthesis of Oriented Meso-Structure Silica Film by Ferrocenyl Surfactant
Authors: Zhou H.S. , Honma I.
Published: April 2011

Self-assembly of organic-inorganic molecules into highly order nanostructured architectures have attracted increasing attention because these materials provide a rich source for scientific research and technological applications. We report the synthesis of an oriented silica mesostructured film by ferrocenyl surfactant templating using a spin coating method. The oriented silica meso-structure film was prepared as follows: tetraethoxysilane (TEOS) was partially hydrolyzed by a substoichiometric amount of pure water mixed with ethanol (EtOH) under acidic condition. The solution became homogeneous as the hydrolysis proceeded, then, ferrocenyl TMA was added, the mixture was stirred at room temperature for about 1 hour, and finally, the film was obtained by spin coating the hybrid sol. X-ray diffraction pattern of the film showed that the film oriented in a lamellar structure with (100) d-space of 36.3 A. The optical and electronic conductivity properties of the film have also been explored.
Analysis of Layered Structures at High Spatial Resolution Using Energy Filtered Imaging
Authors: Flaitz P.L. , Bruley J.
Published: April 2011

The development of energy filtered imaging systems for the TEM has opened new approaches to analyzing structures with very small dimensions. One of the benefits of such systems is the ability to form an EELS spectrum image containing energy information on one axis and spatial information on the other axis. By dissecting such an image in the spatial dimension, it is possible to generate a line profile across a layered structure at high spatial dimension without the need for a small probe. We have applied this approach to two structures typical of semiconductors, the Si/SiO2/Si interfaces in a gate oxide and the Ti/SiO2 interface for Al barrier metallization, which illustrate the spatial resolution possible with this technique. To analyze the spectrum images, the element specific near edge structure (ELNES) data are processed by conventional EELS background routines and multivariate statistical techniques using MATLAB software to extract both profiles of principal bonding components and composition.
Applications of High Resolution Immersion Lens Scanning Electron Microscopes to Sem-Based Defect Review at 250nm Design Rules
Authors: Tracy B.
Published: April 2011

Introduction

The use of SEM-based defect review tools has increased dramatically over the past five years as the semiconductor industry moved from 0.7 micron to 0.25 micron design rules. During this period, a dramatic inflection occurred at the 0.5 micron node; optical microscopy lacked sufficient resolution to determine even if a simple etch step was properly performed. Accordingly, many “inspection SEMs” were introduced into the wafer fabrication facility. With ever increasing focus on yield improvement, defect review SEM's proliferated in the fab in an effort to drive down both baseline defects and process excursions. In order for such an effort to be successful, a clear improvement in the low voltage image resolution performance of the scanning electron microscope was required. Commercial vendors have responded with impressive tools achieving image resolutions of 2.5–4nm @1 kV. At this level of performance, routine observation of semiconductor wafers is possible at 100,000X magnification. This dramatic improvement in resolution is the result of many factors, by far the biggest of which is the use of “immersion lens” designs which employ a strongly excited objective lens operated at short working distances (∼2mm). This electron optic design was first introduced into the laboratory SEM market, with instruments capable of producing approximately 1.2nm resolution at 20kV. These high performance lenses in which the magnetic field extends below the bottom of the polepiece, were fitted onto 200mm platforms allowing whole wafer inspection/defect review. The features of such tools and their application to the IC industry is the subject of this paper. An example of the superb imaging performance of such a 200mm tool is illustrated in figure 1.
The Effect of Growth Temperature and Substrate Misorientation on Degree of Order and Antiphase Domain Size in Ga0.52In0.48P Epilayers Grown on GaAs (001) Substrates by Gs-Mbe
Authors: Meenakarn C. , Staton-bevan A. E. , Najda S. P. , Duggan G. , Kean A. H.
Published: April 2011

A Transmission Electron Microscopy (TEM), Photoluminescence (PL) and Photoluminescence Excitation Spectroscopy (PLE) investigation has been conducted on Ga0.52In0.48P epilayers grown on (001) GaAs substrates by Gas-Source Molecular Beam Epitaxy.For Ga0.52In0.48P epilayers grown on exact (001) GaAs substrates, increasing the growth temperature from 480°C to 535°C increased the antiphase domain plate thickness, t, from 7.3±0.4 to 17.4±0.9 Å, and decreased the long range order parameter, n, from 0.32 to 0.18±0.1. For epilayers grown at 530°C, on GaAs(001) substrates off-cut 0°, 7°, 10° and 15° towards [111]A, increasing the substrate misorientation from 0° to 15° decreased the antiphase domain plate thickness, from 12.3±0.6 to 6.0±0.3 Å. The long range order parameter also decreased from 0.19 to 0.10±0.01.

The band gap energies of these samples, grown by GS-MBE, were close to those reported
for fully disordered Ga0.52In0.48P epilayers grown by MOCVD at ∼760°C. This shows that GSMBE is also a good technique to grow GaInP for high band gap optical data storage applications and at lower growth temperatures. The optimum growth conditions in this study were at a growth temperature of 530°C on (001) GaAs substrate with 15° off-cut towards [111]A.
Crystallographic Mapping in Scanning and Transmission Electron Micrsocopy with Application to Semiconductor Materials
Authors: Dingley D. J. , Wright S. I. , Dingley D. J.
Published: April 2011

The two sister techniques, Electron Backscatter Diffraction and Orientation Imaging Microscopy which operate in a scanning electron microscope, are well established tools for the characterization of polycrystalline materials. Experiment has shown that the limiting resolution for mapping is the order of 0.1 microns. The basic techniques have been extended to include multiphase mapping. Whereas it has been possible to distinguish between phases of different crystal systems easily, it has not been possible to distinguish between phases that differ in lattice parameter by less than 5 %.

An equivalent transmission electron microscope procedure has been developed. The technique couples standard hollow cone microscopy procedures with dark field microscopy. All possible dark field images that can be produced by tilting the electron beam are scanned to detect under what settings each crystal is brought into a diffracting
condition. Subsequent analysis permits determination of both crystal phase and orientation.
Grain Size Distribution and Degree of Texture in Films Used in Integrated Circuits
Authors: Lindsay R. , Chapman J. N. , Craven A. J. , Mcbain D. , Molchanov I.
Published: April 2011

As miniaturisation proceeds, the electrical properties of conductive films used in modem IC's are increasingly influenced by the grain sizes and the texture of the films. There is a need therefore to devise techniques which can examine these properties. Described in this work are two new cross-sectional TEM techniques for use on fully-processed IC's to determine quantitatively grain size distributions and the degree of texture in a film. The technique which investigates texture is used to determine how quickly the texture develops through a polysilicon film.
High Temperature X-Ray Diffraction in Transmission Under Controlled Environment
Authors: Margulies L. , Kramer M. J. , Williams J. J. , Deters E. M. , McCallum R. W. , Haeffner D. R. , Lang J. C. , Kycia S. , Goldman A. I.
Published: April 2011

A compact tube furnace has been developed for high temperature X-ray diffraction studies using high energy synchrotron radiation. The furnace design has a low absorption path in transmission yet allows for a high degree of control of the sample atmosphere and a minimal temperature gradient across the sample. The design allows for a maximum temperature of 1500°C with a variety of atmospheres including inert, reducing, and oxidizing. Preliminary results obtained at the SRI-CAT I-ID undulator line (60keV) at the APS facility and the A2 24 pole wiggler line (45keV) at CHESS on the Ti5Si3Z5 (Z = C, N, O) system will be presented to demonstrate the feasibility of this approach.
Applications of Synchrotron Infrared Microspectroscopy to the Study of Inorganic-Organic Interactions at the Bacterial- Mineral Interface
Authors: Holman Hoi-Ying N. , Perry Dale L. , Martin Michael C. , Mckinney Wayne R.
Published: April 2011

Synchrotron microspectroscopy has been used to study the inorganic-organic interactions in the mid-infrared region (4000#x2013;400 cm#x2212;1) as Arthrobacter oxydans attach themselves to magnetite surfaces. Relative band intensities and band intensity ratios for functional groups of organically-derived biological molecules that are inherent to the experimental system are discussed. The molecular components as they are perturbed by interactions with water, dichromate and chromate metal ions on the mineral surfaces are investigated. Mapping of the spectral markers for the inorganic-organic interactions at the biological- mineral interfaces is presented and discussed. Comparative analyses of the synchrotron infrared microspectra suggest that the bacterial-chromium interactions depend on the solubility and toxicity of the chromium compounds.
Angle-Resolved Photoemission Study of The Electronic Structures of Auai1 and Ptga2
Authors: Hsu L.-S. , Denlinger J. D. , Allen J. W.
Published: April 2011

In this work, in-situ doped polysilicon and poly-SiGe films have been used as the gate material for the fabrication of MOS devices to evaluate their respective performances. These films were deposited in an RTCVD system using a Si2H6 and GeH4 gas mixture. MOS capacitors with 45 Å thick gate oxides and polysilicon/poly-SiGe gates were subjected to different anneals to study boron penetration. SIMS analysis and flat band voltage measurements showed much lower boron penetration for devices with poly-SiGe gates than for devices with polysilicon gates. In addition, C-V measurements showed no poly depletion effects for poly-SiGe gates while polysilicon gates had a depletion effect of about 8%. A comparison of resistivities of these films showed a low resistivity of 1 mΩ-cm for poly-SiGe films versus 3 mΩ-cm for polysilicon films after an anneal at 950 °C for 30 seconds.
Electronic Effects At Interfaces In Cu (cr, mo, w, ta, re) Multilayers
Authors: Bello A. F. , Van Buuren T. , Klepeis J. E. , Barbee T. W.
Published: April 2011

Interfacial electronic effects between Cu and the transition metals Cr, Mo, W, Ta, Re, are investigated by determining the strength of the white line absorption resonances on the L3,2 edges of Cu in Cu5/TM5 multilayers. X-ray absorption (XAS) was performed to study the white lines, which are directly related to the unoccupied states of Cu in the multilayers. The metallic multilayers are 2 nm in period and 200 nm in total thickness. Each period contains 5 monolayers of Cu and 5 monolayers of the transition metal: = 40% of the atoms are at interfaces. These material pairs form ideal structures for the investigation of interfacial electronic effects as they form no compounds and exhibit terminal solid solubility. Only weak white lines are observed on the L3,2 edges of Cu since all the d-orbitals are filled. In the Cu/TM multilayers, however, we observed enhancement of the Cu white lines. We attribute this to the charge transfer from the “interfacial Cu atoms” d-orbital to the transition metal layers. Analysis of the white line enhancement enables calculation of the charge transfer calculation from the Cu to the transition metal. Cu shows a charge transfer of about 0.03 electrons/interfacial Cu atom in Cu/Cr, 0.064 in Cu/Mo, 0.35 in Cu/Ta, 0.17 in Cu/W , and 0.23 in Cu/Re. This charge transfer is consistent with the enhanced absorption energy of Cu on these materials as observed in thermal desorption experiments.
The Chemical Environment Of Er3+ In A-Si:Er:H And A-Si:Er:O:H
Authors: Tessler Leandro R. , Piamonteze Cínthia , Iñguez Ana Carola , Alves M. C. Martins , Tolentino H.
Published: April 2011

We have measured extended x-ray absorption fine structure (EXAFS) of the Er LIII edge in a-Si:Er:O:H with different concentrations of Er and O. The samples were prepared by reactive RF co-sputtering from a silicon target partially covered with metallic erbium platelets. They present the characteristic Er 3+ photoluminescence at 1.54 μm as deposited. The FFT of the Er EXAFS provides two well separated peaks. The characteristics of the first peak resemble those of Er2O3. We associate the first neighbor shell with oxygen atoms, even in non intentionally oxygenated samples. The average coordination and Er-O separation are significantly smaller than in Er2O3. This may be the reason why Er3+ luminescence in a-Si:H presents small temperature quenching. The second shell is interpreted as being composed of silicon atoms.
An Exafs Study of Compositional Homogeneity in Sol-gel Processed Potassium Tantalum Niobates
Authors: Wilkinson A. P. , XU J. , Pattanaik S.
Published: April 2011

A series of K(Ta1-x Nbx)O3 solid-solution samples were prepared by direct reaction of oxides and carbonates, a homogeneous sol-gel process, and an inhomogeneous sol-gel process. The inhomogeneous sol-gel samples were prepared by the prehydrolysis of separate KTaO3 and KNbO3 precursor solutions followed by mixing of the resulting sols, drying and calcination. An examination of these samples by EXAFS at the Ta LIII and Nb K-edges, i) illustrated the difficulty of obtaining homogeneous solid solutions via direct reaction of oxides/carbonates, and ii) showed that the homogeneity of a solid-solution could be controlled by varying the hydrolysis procedure used during its sol-gel synthesis.
X-Ray Absorption Spectroscopy Studies of Electrochemically Deposited Thin Oxide Films
Authors: Balasubramanian M. , Melendres C. A. , Mansour A. N. , Mini S.
Published: April 2011

We have utilized “in situ” X-ray Absorption Fine Structure Spectroscopy to investigate the structure and composition of thin oxide films of nickel and iron that have been prepared by electrodeposition on a graphite substrate from aqueous solutions. The films are generally disordered. Structural information has been obtained from the analysis of the data. We also present initial findings on the local structure of heavy metal ions, e.g. Sr and Ce, incorporated into the electrodeposited nickel oxide films. Our results are of importance in a number of technological applications, among them, batteries, fuel cells, electrochromic and ferroelectric materials, corrosion protection, as well as environmental speciation and remediation.
Electronic and Spatial Structure Studies of Cadmium and Zinc Dialkyldithiocarbamate Molecules in Nonaqueous Solutions Used in the Processes Spray Pyrolysis
Authors: Erenburg S. B. , Bausk N. V. , Zemskova S. M. , Tkachev S. V. , Mazalov L. N.
Published: April 2011

CdK EXAFS and 113Cd NMR spectra, ZnK EXAFS and XANES spectra were measured for solutions of cadmium and zinc dialkyldithiocarbamates in organic solvents with different donor numbers: tributylphosphine, methylene chloride, benzene, dibutylsulfide, pyridine, dimethylsulfoxide and for some model compounds. The parameters of the local surroundings of the Cd and Zn atoms for complex forms in solutions were determined using EXAFS . Spatial structure models of the complex forms in a metal chelate - nonaqueous solvent system are suggested. It is established that coordination of nitrogen atoms by cadmium atoms in pyridine solutions is realized for both Cd[(C2H5)2NCS2 ]2 and Cd[(n−C4 H9)2NCS2]2. For the tributylphosphine solution of Cd[(n−C4H9) 2NCS2]2 and Zn[(n−C4H9)2NCS2]2, additional coordination of the phosphorus atoms of the solvent molecules by the metal atoms are established.