bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper Oxidation Studied by In Situ Raman Spectroscopy
Authors: Schennach Robert , Gupper Andreas 
Published: June 2019

AbstractThe growing importance of copper in the semiconductor industry has led to a renewed interest in the properties and growth modes of copper oxides under a variety of conditions. While thermal oxidation of copper has been studied extensively over the last decades, recent surface studies seem to ignore the possible formation of Cu3O2. It has been shown earlier that thermal oxidation of copper leads to multilayer structures, which consist of CuxO, Cu2O, Cu3O2and CuO, depending on the oxidation conditions. These oxides were analysed ex situ using X-ray Photoelectron Spectroscopy (XPS) combined with depth profiling, Linear Sweep Voltammetry (LSV) and Galvanostatic Reduction (GR). In this work it will be shown that Raman Spectroscopy can be used to follow the formation of the different copper oxides in situ. The experiments were performed using a Raman Microscope with a sample heating extension, which enables in situ copper oxidation in air between room temperature and 300 Δ. Raman spectra were acquired in the range between 3000 Δcm-1to 150 cm-1. From these spectra one can see that Cu20 is formed between 70 Δ and 130 Δ, Cu302is formed between 150 Δ and 250 Δ and CuO starts to form at temperatures higher than 250 Δ.
Near-Threshold Electromigration of Damascene Copper on TiN Barrier
Authors: Meyer William K. , Solanki Raj , Evans David 
Published: June 2019

AbstractElectromigration measurements of dual-damascene VLSI copper interconnect with sputtered TiN barrier was performed to measure both long-line (Jmax) performance and EM threshold (JLmax). Wafer-level stress of via chains with various segment lengths was combined with a statistical efficient experiment design to explore various conditions with minimum sample size. Resistance saturation was observed with exponential time constant corresponding to vacancy diffusivity. Time to opens failure by resistance increase follows Black's equation with current exponent n=1.90 and activation energy Ea=0.94 eV. Thermal gradients due to high current stress were characterized and accounted-for in acceleration models.
The Study of Modified Layers in SiCOH Dielectrics using Spectroscopic Ellipsometry
Authors: Worsley Marcus A. , Bent Stacey F. , Gates Stephen M. , Kumar Kaushik , Dalton Timothy , Hedrick Jeffrey C. 
Published: June 2019

AbstractThe current challenge in designing new low-k dielectrics is realizing sufficient mechanical and chemical stability such that the material can be integrated into current damascene schemes. The material of interest in this study is a nonporous SiCOH composite (carbon-doped silicon oxide, also known as organosilicate glass “OSG”) for use as an intermetal dielectric (IMD). During integration of this IMD, processing steps such as etch, resist strip and chemicalmechanical polishing for planarization may chemically alter the outer layer of the dielectric. Here, spectroscopic ellipsometry is used to characterize the modified layer of SiCOH films after exposure to different resist strip plasmas. The data are analyzed based on a 2-layer model, consisting of a carbon-deficient layer on the surface of the low-k SiCOH dielectric. This model is supported by XPS and FTIR data. The effects of two types of plasma etch chemistry on the formation of this modified layer were studied, and differences between the two chemistries were found. The 2-layer model accurately describes the modifications produced by the oxidizing plasma, but its description of the modified layer formed by the plasma involving nitrogen is not complete. A 3-layer model with an additional nitrogen-doped layer is suggested.
Observation of Grain Growth in Cu Films by In-Situ EBSD Analysis
Authors: Field D.P. , Nowell M.M. , Kononenko O.V. 
Published: June 2019

AbstractRecrystallization, grain growth and crystallographic texture evolution in Cu films is an area of importance for IC interconnect fabrication as the film characteristics influence the resulting line microstructure. This study examines Cu films deposited by partially ionized beam deposition onto a sublayer of tantalum nitride and additionally onto alpha- C:H. The films were annealed in-situ in the SEM chamber and intermittent orientation imaging was used to characterize the grain growth and crystallographic texture evolution in the films. Both initial and final textures are weak in each of the films analyzed, but are a function of sublayer material and thickness. Grain size in the Cu films is significantly smaller for the tantalum nitride sublayer than for the á-C:H sublayer.
Wafer Thinning for Monolithic 3D Integration
Authors: Jindal A. , Lu J.Q. , Kwon Y. , Rajagopalan G. , McMahon J.J. , Zeng A.Y. , Flesher H.K. , Cale T.S. , Gutmann R.J. 
Published: June 2019

AbstractA three-step baseline process for thinning of bonded wafers for applications in threedimensional (3D) integration is presented. The Si substrate of top bonded wafer is uniformly thinned to ~35 μm by backside grinding and polishing, followed by wet-etching using TMAH. No visible changes at the bonding interface and damage-free interconnect structures are observed after the thinning process. Both mechanical and electrical integrity of the bonded pairs are maintained after the three-step baseline thinning process, with electrical tests on wafers with multi-level copper interconnect test structures showing only a slight change after bonding and thinning. This thinning process works well for Si removal to an etch-stop layer, although present process uniformity is not adequate to thin bulk Si substrates. Other issues such as wafer breakage and edge chipping during Si thinning and their possible solutions are also addressed.
Some Aspects of the Materials Science of Low-K Integration
Authors: McGahay Vincent 
Published: June 2019

AbstractThe microelectronic industry's transition to low dielectric constant insulators in the wiring levels of integrated circuits has proven to be more difficult than expected. Materials properties are an integral part of the problem, as much for yield as for reliability. Unfortunately, many properties which are important for manufacturing robustness tend to degrade as the dielectric constant is lowered. Although materials properties are a useful guide to low-K manufacturability, inflexibility with regard to specifications could ultimately limit future progress. Application of basic principles of materials science to the integration of low-K dielectrics can give critical insight into the nature of the difficulties. Several examples of problems in low-K integration which benefit from such analysis are given.
Sequential Process Modeling for Determining Process-Induced Thermal Stress in Advanced Cu/Low-k Interconnects
Authors: Yang Kwanho , Waeterloos Joost J. , Im Jang-Hi , Mills Michael E. 
Published: June 2019

AbstractThe thermomechanical reliability of Cu/low-k interconnects, which is directly related to yield problems and premature device failures, has been a major issue. The development of a manufacturing process, which can satisfy the most stringent reliability standards, requires detailed information on the thermomechanical behavior of Cu/low-k interconnects. The thermomechanical behavior of Cu/low-k interconnects is complicated by the fact that processinduced thermal stresses are developed during the manufacturing process. A conventional finite element analysis (FEA) approach has some difficulties to model Cu/low-k interconnects that keep changing during process steps. Therefore, a sequential process modeling technique has been developed to simulate the interconnect behavior to substantially any level of detail and understand the complex thermomechanical behavior of Cu/low-k interconnects while being manufactured. In this paper, we briefly describe a sequential process modeling technique and demonstrate how we use the modeling technique to solve a Cu/SiC delamination problem in a Cu/SiLK* semiconductor dielectric dual damascene test structure.
Accelerated Oxidation of Hydrogen Silsesquioxane Thin Films Facilitated by an Organosilicone Resin Additive
Authors: Harkness Brian R. , Boisvert Ron , Deng Qian , Zhong Ben , Sun Jianing , Gidley David 
Published: June 2019

AbstractIt has been discovered that the incorporation of small amounts of hydrogen silsesquioxaneco-octadecyl silsesquioxane resin into hydrogen silsesquioxane films results in a significant modification of the thermally processed thin film properties compared to standard hydrogen silsesquioxane (HSQ) films derived from FOx ® solutions. These modifications included a doubling of the modulus and significant reduction in the remaining silyl hydride level. Key to the change in properties was an accelerated oxidation of the film during a one-minute hot plate bake step under a partial oxygen atmosphere. A systematic examination of a series of 5 to 30 weight percent resin additive formulations showed improved mechanical properties at lower additive levels but these were neutralized at higher levels by increasing levels of nanoporosity. It is hypothesized that the enhanced oxidation effect is the result of increased oxygen diffusivity into the film facilitated by the hydrocarbon component of the resin additive.
Structure and Properties of Polysilsesquioxanes and Copolymers for Ultra-Low Dielectric Films
Authors: Yoon Do Y. , Ro Hyun Wook , Park Eun Su , Lee Jin-Kyu , Kim Hie-Joon , Char Kookheon , Rhee Hee-Woo , Kwon Dongil , Gidley David W. 
Published: June 2019

AbstractPolysilsesquioxanes (PSSQs) with the empirical formula (RSiO3/2)n have become very important as low-dielectric insulators for copper interconnects in the next-generation logic devices, but the detailed structure-property relationships were completely lacking. We have investigated the microstructure and functional properties of PSSQs with varying alkyl substituents and also PSSQ copolymers. As a result, significant advances have been made in the scientific understanding of PSSQ structures and significant improvements of key properties such as the crack resistance, mechanical modulus and hardness, and incorporation of nanometer-sized (<4 nm) porosity for ultra-low dielectric constants (<2.0).
Creating Nanoporosity by Selective Extraction of Porogens Using Supercritical Carbon Dioxide/Cosolvent Processes
Authors: Lahlouh B. , Rajagopalan T. , Lubguban J. A. , Biswas N. , Gangopadhyaya S. , Sun J. , Huang D. , Simon S. L. , Kim H. C. , Volksen W. , Miller R. D. 
Published: June 2019

AbstractThis work presents a novel approach using supercritical carbon dioxide (SCCO2) to selectively extract poly(propylene glycol) (PPG) porogen from a poly(methylsilsesquioxane) (PMSSQ) matrix, which results in the formation of nanopores. Nanoporous thin films were prepared by spin-casting a solution containing appropriate quantities of PPG porogen and PMSSQ dissolved in PM acetate. The as-spun films were thermally cured at temperatures well below the thermal degradation temperature of the organic polymer to form a cross-linked organic/inorganic polymer hybrid. By selectively removing the CO2 soluble PPG porogen, open and closed pore structures are possible depending upon the porogen load and its distribution in the matrix before extraction. In the present work, two different loadings of PPG namely 25 wt.% and 55 wt.% were used. Both static SCCO2 and pulsed SCCO2/cosolvent treatments were used for PPG extraction. The initial results indicate that the pulsed SCCO2/cosolovent treatment was more efficient. Fourier transform infrared spectroscopy (FTIR) and refractive index measurements further corroborate the successful extraction of the porogens at relatively low temperatures (2000C). For the pure PMSSQ film, the k value is 3.1, whereas it is 1.46 and 2.27 for the open and closed pore compositions respectively after the static SCCO2 extraction and 430°C subsequent annealing. The reduction in the k-value is attributed to the formation of nanopores. The pore structure was verified from transmission electron microscopy (TEM), and from small-angle x-ray scattering (SAXS) measurements, the pore size was determined to be 1-3 nm for these films.
Environmental Effects on Subcritical Delamination of Dielectric and Metal Films from Organosilicate Glass (OSG) Thin Films
Authors: Lin Y. , Vlassak J.J. , Tsui T.Y. , McKerrow A.J. 
Published: June 2019

AbstractSubcritical delamination of dielectric and metal films from organosilicate glass (OSG) thin films was studied in controlled ambient with different levels of relative humidity and in aqueous environments of varying pH. The material systems studied include OSG/SiO2, OSG/TaN and OSG/SiNx. For both sets of experiments, subcritical crack growth in OSG is found to be described by a model originally developed for soda-lime silicate glass. The threshold energy release rate for water molecule-assisted cracking varies linearly with the natural logarithm of water partial pressure. In aqueous environments, the threshold value decreases linearly with increasing pH in accordance with a simple model. The slope of crack growth rate curve also decreases with increasing pH.
Characterization of Nanoporous Low-k Thin Films by Contrast Match SANS
Authors: Hedden Ronald C. , Bauer Barry J. , Lee Hae-Jeong 
Published: June 2019

AbstractSmall-angle neutron scattering (SANS) contrast variation is used to characterize matrix properties and pore size in nanoporous low-dielectric constant (low-k) thin films. Using a vapor adsorption technique, SANS measurements are used to identify a “contrast match” solvent mixture containing the hydrogen– and deuterium-containing versions of a probe solvent. The contrast match solvent is subsequently used to conduct SANS porosimetry experiments. With information from specular X-ray reflectivity and ion scattering, the technique is useful for estimating the mass density of the matrix (wall) material and the pore size distribution. To illustrate the technique, a porous methylsilsesquioxane (MSQ) spin-on dielectric is characterized.
Novel Process Methodology for Uniformly Cutting Nanotubes
Authors: Lustig Steven R. , Boyes Edward D. , French Roger H. , Gierke Timothy D. , Harmer Mark A. , Hietpas Paula B. , Jagota Anand , Mitchell Greg P. , Onoa G. Bibiana , Sams Kerry D. 
Published: June 2019

AbstractWe present a novel process methodology for the controlled cutting of nanotubes and other nanostructures to well-controlled lengths and sizes. The continuing increase in complexity of electronic devices, coupled with decreasing size of individual elements, are placing more stringent demands on the resolution and accuracy of fabrication patterns. The ability to fabricate on a nanometer scale guarantees a continuation in miniaturization of functional devices. Particularly interesting is the application of nanotubes' chemical and electronic properties which vary with their dimensions and structure. One realization of this process includes the use of photolithography or electron beam lithography to place protective resist patterns over the nanostructures to be cut. Those sections which are not covered by the resist pattern are removed by reactive ion etching. This is a scaleable process which permits the simultaneous cutting of many nanostructures and ensembles of nanostructures. The lengths, shapes or length distributions can be predicted from theory and thus specified for a given application requirement. Nanostructures which can be cut in this process include nanotubes, nanofibers and nanoplanes. Large scale production of nanostructures with uniform length or specific size-distribution can be used in electronic applications such as field-emission transistors, optoelectronic elements, single electron devices and sensors.
Advances in Cnx Nanotube Growth
Authors: Liu J. , Czerw R. , Webster S. , Carroll D.L. , Park J. H. , Park Y. W. , Terrones M. 
Published: June 2019

AbstractCarbon nanotubes containing substitutionally “doped” nitrogen were synthesized using injection chemical vapor deposition methods. X-ray photoelectron spectroscopy comparisons between materials grown with different nitrogen sources suggest that the nitrogen content of the nanotubes has little correlation with the total nitrogen content of the “dopant” gas. Tunneling microscopy and spectroscopy do, however, confirm that drastic distortions occur within the graphene lattice as the nitrogen is substituted. Further, donor states are clearly identifiable within the density of electronic states.
The Effects of Catalyst Grain Sizes on the Diameter of MPECVD Grown Patterned Carbon Nanotubes
Authors: Wang S. G. , Zhang Qing , Zhong G. F. , Yoon S. F. , Ahn J. , Yang D. J. 
Published: June 2019

AbstractThe electronic structure and properties of carbon nanotubes (CNTs) strongly depend on their diameter and chirality. The well controlled CNTs diameter is becoming one of the challenges for their applications in microelectronics. In this paper, the patterned CNTs were produced by microwave plasma enhanced chemical vapor deposition technique using a metal catalyst of nickel. The correlation between the CNT diameter and the grain sizes of the nickel catalyst was examined. The experimental results show that nickel films converted to nickel particles when they were heated up. The diameter of CNTs increases with increasing grain sizes of the nickel particles, indicating that the CNT diameter can be controlled by controlling the grain sizes of the nickel catalyst.
Electronic Device Fabricated From Polyaniline / Single walled Carbon Nanotubes Composite
Authors: Ramamurthy P.C. , Malshe A.M. , Harrell W.R. , Gregory R.V. , McGuire K. , Rao A.M. 
Published: June 2019

AbstractComposites of high molecular weight polyaniline and single walled carbon nanotubes are investigated for applications to electronic devices. Electrical characteristics of devices fabricated using this composite show an order magnitude higher current level than those measured in the neat polyaniline devices. Composite materials and devices with various weight percentages of single walled carbon nanotubes were also fabricated. Current-voltage (I-V) characteristics of these devices indicate a significant increase in current with an increase in carbon nanotube concentration in the composite. Analysis of the forward I-V characteristics of these composite devices on a log-log scale shows two power law regions. In the lower voltage range, the exponent is 1, which is consistent with ohmic conduction, while in the higher voltage range, the exponent is between 1.1 and 1.5, which is consistent with space-charge-limited conduction.
Self-Assembly Fabrication of High Performance Carbon Nanotubes Based FETs
Authors: Valentin Emmanuel , Auvray Stephane , Filoramo Arianna , Ribayrol Aline , Goffman Marcelo , Capes Laurence , Bourgoin Jean-Philippe , Patillon Jean-Noel 
Published: June 2019

AbstractWe describe the realization of high quality self-assembled single wall carbon nanotube field effect transistors (CNTFET). A method using self-assembled monolayers (SAMs) is used to obtain high yield selective deposition placement of single wall carbon nanotubes (SWNTs) on predefined regions of a substrate. This is achieved with individual or small bundles of SWNTs and with high densities suitable for fabrication of integrated devices. We show that such positioned SWNTs can be electrically contacted to realize high performance transistors, which very well compare with state-of-the-art CNTFETs. We therefore validate the self-assembly approach to reliably fabricate efficient carbon nanotube based devices.
Fabrication of Carbon Nanotube Triode Using Helicon Plasma Cvd with Electroplated Nico Catalyst
Authors: Muroyama Masakazu , Kimura Kazuto , Yagi Takao , Saito Ichiro 
Published: June 2019

AbstractA carbon nanotube triode using Helicon Plasma-enhanced CVD with electroplated NiCo catalyst has been successfully fabricated. Isolated NiCo based metal catalyst was deposited at the bottom of the cathode wells by electroplating methods to control the density of carbon nanotubes and also reduce the activation energy of its growth. Helicon Plasma-enhanced CVD (HPECVD) has been used to deposit nanotubes at 400°C. Vertically aligned carbon nanotubes were then grown selectively on the electroplated Ni catalyst. Field emission measurements were performed with a triode structure. At a cathode to anode gap of 1.1mm, the turn on voltage for the gate was 170V.
High Concentration Aqueous Mixtures of Single Walled Nanotubes
Authors: Grunlan Jaime C. , Bannon Michael V. 
Published: June 2019

AbstractGum arabic (GA) and polyvinylpyrrolidone (PVP) were used to stabilize relatively high concentration mixtures of single walled carbon nanotubes (SWNTs) in water. Viscosity and electrical conductivity data, along with electron microscopy, suggest that PVP interacts much more strongly with nanotubes than GA does. This strong PVP-SWNT relationship results in better dispersion of the nanotubes, resulting in lower electrical conductivity, but may enhance mechanical behavior in polymer-matrix composites.
Fracture Toughness of Nanocrystalline L12 (Al+X at.%Mn)3 Ti Prepared by Mechanical Alloying and Consolidated by SPS
Authors: Jang Hee Sup , Kang Chang Won , Kim Young-Seok , Kim Seon-Jin 
Published: June 2019

AbstractThe effects of ternary element addition of manganese on microstructure and mechanical properties of nanocrystalline L12 (Al+X at.%Mn)3Ti (X=0 - 12) fabricated by mechanical alloying and spark plasma sintering (SPS) were investigated. The SPS method was used to consolidate nanocrystalline L12 (Al+X at.%Mn)3Ti with the pressure of 50 MPa. The heating rate was 100°C /min. The final sintering temperature was determined from the observation of the shrinkage of the specimen. In binary Al3Ti, the final sintering temperature was 864°C. The sintering temperature was reduced down to 658°C with increasing Mn concentration. After SPS, the L12 structure was maintained in the specimens which contained Mn concentration of 8- 12 at.%. The microhardness test, grain size measurements, and fracture toughness test were conducted as a function of Mn concentration. In order to investigate the effect of the grain size on the microhardness and fracture toughness of the (Al+8 at.%Mn)3Ti, heat treatments were performed in a vacuum furnace ( 10-3 torr ). With increasing heat treatment temperature, the microhardness decreased due to the formation and growth of Al4C3, Al2O3, and TiC, while fracture toughness increased. The fracture toughness of 4.12 MPa m1/2 was attained for the (Al+8 at.%Mn)3Ti specimen and it was the highest value among the specimens after 1h heat treatment at 1100°C. The grain sizes were about 60 nm and 100 nm after 1 h heat treatment at 900°C and 1100°C, respectively.
Indentation Techniques for the Study of Deformation Across Grain Boundaries
Authors: Nibur K. A. , Bahr D. F. 
Published: June 2019

AbstractThe mechanism by which deformation is transferred across grain boundaries and ways in which boundaries of different misorientations impact this process has been studied using indentation testing. This information could be useful in designing texture of nanocrystalline materials to maximize their mechanical properties for specific applications. Atomic force microscopy (AFM) and orientation imaging microscopy (OIM) has been combined to identify slip systems activated around indentations. When indentations are placed near grain boundaries, slip steps can be imaged on both sides of the boundary and the associated slip systems of each grain can be determined. Dislocation pile ups have been observed around indentations near boundaries which do not share a common slip direction with the active slip planes of either grain, and slip steps have been seen to traverse boundaries when these shared slip directions are present.