bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and Mapping of Nanotopography Interactions with CMP
Authors: Lee Brian , Boning Duane S. , Baylies Winthrop , Poduje Noel , Valley John 
Published: June 2019

AbstractAs the demand for planarity increases with advanced IC technologies, nanotopography has arisen as an important concern in shallow trench isolation (STI) chemical mechanical polishing (CMP) processes. Previous work has shown that nanotopography, or small surface height variations on raw wafers 20 to 50 nm in amplitude extending across millimeter scale lateral distances, can result in substantial CMP-induced localized thinning of surface films such as oxides or nitrides used in STI [1]. This interaction with CMP depends both on characteristics of the wafer such as heights and spatial wavelengths of the nanotopography, and characteristics of the CMP process including the planarization length or pad stiffness.In this paper we review and extend the previous work on modeling of nanotopography. Three approaches to predicting the post-CMP oxide thinning due to nanotopography are compared. The first approach is the simplest, where a statistical aggregate effect is computed. Following the work of Schmolke [2], a transfer coefficient α is found which captures the portion of the nanotopography that is correlated with the final oxide thinning. The second approach is the most detailed, depending on explicit numerical simulation of pad elastic properties. In this case, a contact wear simulation is used to produce a detailed map of oxide thickness corresponding to any given pre-measured nanotopography wafer surface. The third approach is a signal processing method, sitting somewhere between the previous two extremes in terms of approximation and complexity. In this last case, a two-dimensional transfer function is extracted which captures the spatial smoothing accomplished by CMP. This filter can then be applied efficiently to premeasured nanotopography maps for other wafers to predict the final oxide thicknesses.We also propose a predictive mapping of post-CMP oxide or nitride thicknesses to provide insight into the relative goodness of a wafer measured for nanotopography which is to be subjected to a CMP process. Specifically, we suggest that for post-CMP impact, maps and computation of areas having insufficient oxide clearing, or having final nitride thickness outside of required ranges, are useful and practical. Such device failure potential maps complement the fundamental nanotopography height map data and metrics based directly on that data, and enable evaluation, comparison, and development of improved wafers and STI CMP processes.
Evaluation of Monodispersed Silica Particles and Ceria Coated Silica Particles for Chemical Mechanical Polishing
Authors: Lu Zhenyu , Lee Seung-Ho , Matijević Egon , Babu S. V. 
Published: June 2019

AbstractThe properties of abrasive particles play a key role in chemical mechanical polishing (CMP). This study used well-defined dispersions of uniform particles, including spherical silica of varying diameters to polish Cu films and silica cores coated with nanosized ceria particles to polish oxide films. It was shown that the total surface area of the silica abrasives in the slurry controlled Cu material removal rate. However, pH, solid content, and particle size of ceria coated silica abrasives did not have a strong correlation to the removal rate of oxide films.
Optimization of Deposition Thickness and Over Polishing Time to Minimize Wafer Level Topography in Copper CMP
Authors: Kang J.M. , Wu Shaoyu , Selvaraj T. , Lin Benfu , Foo P.D. 
Published: June 2019

AbstractTopography after Cu CMP is one of the main issues in constructing reliable Cu interconnects. The wafer level topography is greatly influenced by many polishing properties such as removal non-uniformity and planarization efficiency, and also by many polishing variables. Among the variables, Cu deposition thickness and over polishing time are easily controllable, and closely related to the topography. For a given polishing condition, the topography can be minimized through the optimization of Cu deposition thickness and over polishing time. A model is proposed to account for the correlation between these variables and the wafer level topography. Numerical result of this model shows a strong dependency of optimized Cu deposition thickness and over polishing time on the removal non-uniformity, dishing susceptibility and over plated bump size.
Reaction Control in Amorphous Silicon Film Deposition by Hydrogen Chloride
Authors: Takano Akihiro , Wada Takehito , Fujikake Shinji , Yoshida Takashi , Ohto Tokio , Aydil Eray S. 
Published: June 2019

AbstractHCl was added to SiH4 containing plasmas to grow a-Si:H(Cl) films with dangling bonds terminated with Cl instead of H. Bulk and surface infrared spectra, film thickness and optical band gap were examined by in situ multiple total internal reflection Fourier transform infrared spectroscopy and in situ spectroscopic ellipsometry. SiH2Cl2 was also used as a conventional Cl source for reference a-Si:H(Cl) film deposition experiments. The introduction of HCl does not affect the deposition rate significantly, and the deposited a-Si:H(Cl) films contain over 1021cm-3 Cl atoms. HCl addition to the gas phase changes the surface compositions of the growing films drastically from higher silicon hydride to chlorinated lower hydride. The surface reaction control eliminates unfavorable hydride bonding structures such as SiH2 and/or SiH in voids in the deposited films. The a-Si:H(Cl) films deposited from mixtures of SiH4 and HCl do not show significant optical band gap widening in spite of containing over 1021cm-3 Cl atoms, a concentration that is comparable to that of hydrogen. In contrast, a conventional chlorine source of SiH2Cl2 increases the deposition rate significantly compared to HCl. The increase in the deposition rate results in monotonic decrease of the refractive index and the optical band gap widening.
Advanced Lateral Crystal Growth of a-Si Thin Films by Double-Pulsed Irradiation of All Solid-State Lasers
Authors: Kudo Toshio , Seike Koji , Yamazaki Kazunori , Komori Hirohito , Yawaka Sachi , Hamada Shiro , Jin Cheng-Guo 
Published: June 2019

AbstractA compact annealing machine with all solid-state green lasers has been developed, which has the advantage of widely adjustable solidification rate through the delay time control of two long pulses (pulse width ~100ns). Advanced lateral crystal growth (ALCG) process has been proved by the double-pulsed all solid-state laser annealing. The laser beam has a line shape 0.1mm wide and 17mm long, and the beam profile on the short axis is quasi-Gaussian (FWHM 0.1mm). Scanning the line beam along the short axis at the 86% overlapping ratio, the lateral crystal growth area of width 14μm, parallel to the long axis, is sequentially formed at the pitch of 14μm towards the scanning direction. The advanced lateral growth mechanism is easily explained as follows: (1) At the first irradiation, twin seed lines of width 4μm, parallel to the long axis, generates at a boundary between a near-complete melting region and a complete melting region. (2) At the second irradiation of scanning step 14μm, the front seed line in the scanning direction grows symmetrically toward both sides. (3) At the third irradiation of scanning step 2x14μm, the seeds laterally grow until stopped by the growing of seeds on both sides. Finally the ALCG process by the scanning line-beam technique like the current ELA enables us to produce the laterally grown Si thin-films sequentially arranging the belt-shaped texture at the pitch of 14μm. The quality of the laterally grown Si films is quite well except for the projections generated by the bump of lateral growing seeds.
Improved Electrical Properties in Nanocrystalline Si Formed by Metal Induced Growth
Authors: Ji Chunhai , Anderson Wayne A. 
Published: June 2019

AbstractIn recent work, the electrical properties of metal-induced-grown (MIG) Si thin films were studied by using current-voltage (I-V) data from a metal/Si Schottky contact. It was found that controlling the doping level of the films and annealing in forming gas (15% H2 and 85% N2) can improve the quality of the nc-Si films. From SIMS analysis on the nc-Si film deposited from a highly doped target, the nc-Si can duplicate the doping level of the sputtering target. Study of p-type doped nc-Si films showed that the fabrication of Schottky diodes on nc-Si films made from an extremely high-doped target (∼1020 cm-3) or low-doped target (∼1015cm-3) was not successful. For highly doped p-type films, tunneling causes Ohmic conduction instead of rectifying conduction. For the nc-Si film deposited from a low-doped p-type target, the film shows conversion to n-type characteristics when measured by a hot probe. This might be due to defects or oxygen in the film. N-type films at the middle doping level (∼1017cm-3) gave good Schottky diodes after annealing the film in forming gas at 700°C. The Schottky diodes fabricated by high work-function metal (Au) gave the rectifying ratio of ~∼103. Several techniques, e.g. slow/fast two-step sputtering at low working pressure and surface polishing, were used to improve the photo response of Schottky photodiodes. The open-circuit voltage (Voc) of 0.164V and short-circuit current density (Jsc) of 2.5 mA/cm2 were achieved under 100mW/cm2 illumination.
A Study of Electronic Defects in Hydrogenated Amorphous Silicon Prepared by the Expanding Thermal Plasma Technique
Authors: Reynolds Steve , Main Charlie , Zrinscak Ivica , Aneva Zdravka , Nesheva Diana 
Published: June 2019

AbstractThe electronic properties of amorphous silicon films prepared by the expanding thermal plasma technique have been studied using steady-state and transient photoconductivity measurements. It is found that films deposited at a substrate temperature of 400°C have a conduction band tail slope of 29 meV, deep defect density of order 3×1016 cm-3, an Urbach tail slope of 65 meV, defect absorption of 5-10 cm-1, and a mobility-lifetime product of 1.3×10-7 cm2 V-1. Aslight increase in defect density and reduction in mobility-lifetime product is observed on moderate light-soaking. The overall optoelectronic quality is somewhat poorer than commercial PECVD material, but there is scope for improvement as deposition conditions are further optimised.
Electron-Spin-Resonance Investigation of Laser Crystallized Polycrystalline Silicon
Authors: Brendel K. , Nickel N. H. , Lips K. , Fuhs W. 
Published: June 2019

AbstractDoped and undoped laser crystallized polycrystalline silicon was investigated by electron-spin-resonance experiments. In P-doped samples two resonance are detected at g = 2.0053 and g = 1.998 which are due to silicon dangling bonds and conducting electrons, respectively. After crystallization a large amount of hydrogen remains in the samples. This residual hydrogen can be activated to reduce the spin density by passivating dangling-bonds. The temperature dependent investigation of the conducting electron resonance reveals that the susceptibility can be described by the sum of Pauli and Curie paramagnetism. The data are discussed in terms of models developed for single crystal and microcrystalline silicon.
Optoelectronic Detection of DNA Molecules Using an Amorphous Silicon Photodetector
Authors: Fixe F. , Prazeres D.M.F. , Chu V. , Conde J.P. 
Published: June 2019

AbstractThis work demonstrates the use of an amorphous silicon (a-Si:H) photodetector to measure the density of covalently-bound DNA molecules tagged with a fluorescent molecule. This device is based on the photoconductivity of a-Si:H in a coplanar electrode configuration. Excitation of a fluorescently-tagged biomolecule with near UV/blue light results in the emission of visible light. The emitted light is then converted into an electrical signal in the photodetector, thus allowing the detection of the presence of the tagged DNA molecules. The design, fabrication and characterization of this integrated a-Si:H-based bio-detector is described. The detection limit of the present device is of the order of 20 pmol/cm2. A surface density of ≤ 30 pmol/cm2 for DNA covalently-bound to an active silica layer was measured with the a-Si:H-based bio-detector.
Process Parameters for Poly-Silicon Deposition at a High Growth Rate (1-7 nm/s) by Hot-Wire Chemical Vapour Deposition
Authors: Rath J.K. , Hardeman A.J. , Werf C.H.M. van der , Veenendaal P.A.T.T. van , Rusche M.Y.S. , Schropp R.E.I. 
Published: June 2019

AbstractHigh silane to hydrogen flow ratios and optimum wire temperatures are the key process parameters to achieve high growth rate poly-silicon films by hot wire chemical vapour deposition (HWCVD) using a four-wire hot-wire assembly. Four tungsten wires, 4 cm apart from each other, were used as catalytic filaments. Growth rates higher than 7 nm/s have been achieved at a substrate temperature of ∼510°C. The increase in deposition rate was accompanied by deterioration of two physical properties i.e., decrease in photoresponse and increase in oxygen incorporation in the film, which is attributed to high porosity in the material that is commonly observed in these high growth rate materials. The process conditions to incorporate a high hydrogen content into the material for passivation of defects and donor states have been identified as high hydrogen dilution and lower wire temperature. With these procedures, poly-Si films deposited at 1.3 nm/s showed a high ambipolar diffusion length of 132 nm. Incorporating such poly-Si films as the i-layer in an n-i-p solar cell on a stainless steel substrate, without back reflector, showed an efficiency of 4.4 % and a high open circuit voltage of 0.58 V, which is attributed to effective passivation of defects and dopants by incorporated hydrogen.
Simulations of Buffer Layers in a-Si:H Thin Film Solar Cells Deposited with an Expanding Thermal Plasma
Authors: Petit A.M.H.N. , Zeman M. , Swaaij R.A.C.M.M. van , Sanden M.C.M. van de 
Published: June 2019

AbstractWith an Expanding Thermal Plasma Chemical Vapor Deposition system (ETP-CVD), solar grade amorphous silicon (a-Si:H) can be deposited at high deposition rate (> 2 nm/s). We think that during the first stage of deposition, a material is grown with a higher defect density than the rest of the bulk creating a defect-rich layer (DRL). Therefore we analyzed, by the means of simulations, the influence of the position of the DRL on the performance of a p-i-n a-Si:H solar cell when moved from the p-i towards the i-n interface and as a function of its thickness. We investigate the effect of a buffer layer in between the p- and the i-layer on the external parameters of the solar cell. The presence of a buffer layer increases the electric field near the p-i interface, which leads to a higher collection of free charge carriers at the interface, although the electric field is then diminished deeper in the bulk. It appears that 10 nm thick buffer layer is sufficient to improve the performance. In case no buffer layer is applied, recombination losses at the p-i interface diminish the performance of the solar cell. We also observe that an increase of the DRL thickness results in a reduction of the solar-cell performance, which is more pronounced when the DRL is located in the region close to the p-i interface rather than close to the i-n interface.
Evaluation of Copper Ion Drift in Low-Dielectric-Constant Interlayer Films by Transient Capacitance Spectroscopy
Authors: Yoshino Takenobu , Hata Nobuhiro , Kikkawa Takamaro 
Published: June 2019

AbstractThe evidence of copper (Cu) ion drift in low-dielectric-constant (low-k) interlayer films is clearly shown by transient capacitance measurements for the first time. The bias-temperaturestress (BTS) was applied to the copper electrode of Cu/low-k/p-Si metal-insulator-semiconductor capacitors. After injecting photoelectrons into the low-k film from the substrate, time-dependence of the capacitance was measured. When BTS-applied samples were measured, a decrement of the capacitance was observed, whereas not observed without BTS. The decrement of the capacitance was attributed to thermal emission of electrons from copper-related electronic states. By assuming an attempt-to-escape frequency of the charge from the electronic states, the energy level of Cu was estimated to be 0.8–0.9 eV below the conduction band edge.
Mim Capacitors with HfO2 and HfAlOx for Si RF and Analog Applications
Authors: Yu Xiongfei , Zhu Chunxiang , Hu Hang , Chin Albert , Li M.F. , Cho B.J. , Kwong Dim-Lee , Foo P.D. , Yu M.B. 
Published: June 2019

AbstractThe MIM capacitors with HfO2 and HfAlOx are investigated for Si RF and analog applications. The results show that both the capacitance density and voltage coefficients of capacitance (VCCs) increase with decreasing the HfO2 thickness. A high capacitance density of 13 fF/μm2with a low leakage current and a VCC of 607 ppm/V is obtained for 10 nm HfO2 MIM capacitor, which can meet the requirement of the ITRS roadmap by 2007 for silicon RF application. On the other hand, it was found that both the capacitance density and voltage coefficients of capacitance (VCC) values of the HfAlOx MIM capacitors decrease with increasing Al2O3 concentration. The results show that HfAlOx MIM capacitor with an Al2O3 mole fraction of 0.14 is optimized. It provides a high capacitance density of 3.5 fF/μm2 and a low VCC of μ140 ppm/V2. Also, small frequency dependence, low leakage current, and low loss tangent are obtained. Thus, the HfAlOx MIM capacitor with an Al2O3 mole ratio of 0.14 is very suitable for use in silicon analog applications.
Stress Stability of PECVD Silicon Nitride Films During Device Fabrication
Authors: Hughey Michael P. , Cook Robert F. 
Published: June 2019

AbstractConventional, dense dielectrics serve as structural elements in Cu/low-k interconnect structures, and a full understanding of their thermo-mechanical properties is desired to help optimize device fabrication and avoid mechanical failure. Wafer curvature measurements were made on plasma-enhanced chemical vapor deposited (PECVD) silicon nitride films during thermal cycling to explore the large, irreversible, tensile stress developed. Spectroscopic techniques were used to probe the composition and structure of the films after annealing steps and indicate that reaction of hydrogen-containing defects provides the mechanism for stress change. A simple kinetic model, modified by the inclusion of an equilibrium function of hydrogen defects, is proposed and is found to adequately describe stress development.
Interfacial Relationships in Microelectronic Devices
Authors: Lane Michael , Rosenberg Robert 
Published: June 2019

AbstractThe continued shrink of interconnect structures is requiring new materials to be introduced into back-end of the line (BEOL) devices at an increasing rate. These new materials must provide a performance benefit from the previous generation with the recent focus on reducing the effective dielectric constant of the integrated structures. This reduction may occur not only by changing the intralevel dielectric but also by changing the capping layer/diffusion barrier on the chemicalmechanically polished (CMP'd) Cu surface. However, changing this material may alter the reliability of the device structure due to a change in the Cu/cap interface bonding. Another consequence of the decrease in minimum feature size in interconnects is that commonly practiced techniques, such as sputtered liner and Cu seed, may not be extendable to future generations. Accordingly, the focus of this paper is on identifying basic relationships between interfacial chemistry and interfacial adhesion and illustrating how those relationships can be used to address some of the issues that may pose problems in future technologies.
Advanced characterization of ultra-low-k periodic porous silica films – pore size distribution, pore-diameter anisotropy, and size and macroscopic isotropy of domain structure
Authors: Hata N. , Negoro C. , Takada S. , Yamada K. , Oku Y. , Kikkawa T. 
Published: June 2019

AbstractWe have shown previously the results from out-of-plane and in-plane X-ray scattering /diffraction measurements together with transmission electron microscope and X-ray reflectance measurements and shown that they are effective in characterization of a periodic porous silica low-k film [1]. In the present work, we report the results on pore-size distribution, pore-diameter anisotropy, and size and macroscopic isotropy of domain structure.
Synthesis of C and CNx Nanotubes, Using the Aerosol Method
Authors: Glerup M. , Castignolles M. , Holzinger M. , Kanzow H. , Loiseau A. , Bernier P. 
Published: June 2019

AbstractHere we will present the state-of-the-art of the aerosol synthesis method. We demonstrate the reliability of this method by showing that the method can be successfully used for the synthesis of C and CNx multi walled nanotubes. For characterization, scanning- (SEM) and high resolution transmission electron microscopy (HRTEM) imaging have been carried out. The N/C ratio is determined using Electron Energy Loss Spectroscopy (EELS) combined with TEM.
Modification of Electrical and Mechanical Properties of Single Wall Carbon Nanotubes by Reaction with SOCl2
Authors: Dettlaff-Weglikowska Urszula , Skakalova Viera , Graupner Ralf , Ley Lothar , Roth Siegmar 
Published: June 2019

AbstractAttaching chemical functional groups to single wall carbon nanotubes (SWNTs) has been achieved by chemical methods. Oxidized purified nanotubes have been treated by thionyl chloride in order to convert carboxyl groups into acylchloride groups. We observe by XPS and EDX that not only chlorine atoms but sulphur containing functional groups are covalently bound to the nanotubes. This chemical functionalization also causes significant changes in the electrical and mechanical properties of the nanotubes. The electrical conductivity measured on mats (bucky paper) increases from 500 S/cm in pristine tubes to 2500 S/cm in modified tubes. Similarly, the Young's modulus of bucky paper increases by about 100 %.
Measurements of Size Scale Effects in Layered Structures
Authors: Bastawros Ashraf , Antoniou Antonia 
Published: June 2019

AbstractA novel experimental configuration is devised to measure the evolution of the deformation field and the corresponding hardening evolution within soft metallic films constrained by hard layers. The experimental configuration provides pure shear state within the constrained film. The material system utilized comprised ductile layer of tin based solder, encapsulated within relatively hard copper shoulders. Different tin-lead compositions are tested with grain size approaching the film thickness. The in-plane strain distribution within the film layer is measured by a microscopic digital image correlation system. The hardening evolution within such highly gradient deformation field is monitored qualitatively through a 2D surface scan with a nanoindentor. The measurements showed a highly inhomogeneous deformation field within the film with discreet shear bands of concentrated strain. The localized shear bands showed long-range correlations of the order of 3-4 the grain size. A size-dependent macroscopic response on the layer thickness is observed. However, the corresponding film thickness is approximately 100-1000 times larger than those predicted by non-local continuum theories and discrete dislocation.