bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adhesion Energy Measurements of Multilayer Low-K Dielectric Materials for ULSI Applications
Authors: Shaffer E. O. , Mills M. E. , Hawn D. , Van Gestel M. , Knorr A. , Gundlach H. , Kumar K. , Kaloyeros A. E. , Geer R. E. 
Published: April 2011

ABSTRACTCurrently, the IC industry is researching the integration of a variety of materials to meet the low dielectric constant requirement for improved back-end of line (BEOL) interconnect performance. One critical dimension for successful ntegration of these new materials is maintaining mechanical integrity through multilayer processes. This includes both cohesive and adhesive fracture resistance. The latter adds additional complexity in that adhesive toughness is a function of the adherend materials and the processes used to join them. Hence, many good dielectric materials may be rematurely eliminated from further research not because of inherently poor adhesion but because of the necessity to optimize processing strategies.In this paper, we use the modified Edge Liftoff Test (m-ELT) to quantify the mechanical adhesion of multilayer blanket coatings. A specific example is used to demonstrate the utility of combining the m-ELT with surface analysis to optimize the reliability of low-K dielectric resins for use in ULSI applications. The system studied consists of a Cyclotene™5021(BCB) low-K material integrated with CVD aluminum for single level, damascene structures. The effects of liner layer metallurgy and surface plasma treatments are measured. Surface analysis is done on the failed parts to understand the location of the failure. In this way recommendations for process optimization can be made.
Study of the thermal properties of polymeric dielectric materials by photothermal technique
Authors: Hu Chuan , Ogawa Ennis T. , Hay Michael F. , Ho Paul S. 
Published: April 2011

ABSTRACTIn this paper, we present some results of the newly developed on-wafer photothermal measurement. To study thermal anisotropy, the out-of-plane thermal diffusivity measured from this technique is compared with the in-plane thermal diffusivity by measured by ISTS [1]. In addition to the thermal properties, the agreement with mechanical [2] and optical properties are also shown. The significance of different thermal performance between low K dielectric medium materials and SiO2 suggests that greater attention should be paid to thermal properties for integrated devices with low K materials.
Dielectric Behavior and Phonon Damping in Low-Dielectric Constant Perovskite Materials
Authors: Katiyar Ram S. , Siny Igor , Guo R. , Bhalla A. S. 
Published: April 2011

ABSTRACTWe have carried out a comparative study of the dielectric losses in some complex perovskites with both 1:1 and 1:2 compositions of the B ions, namely, SrAl1/2Nb1/2O3 (SAN), SrAl1/2Ta1/2O3 (SAT) and BaMg1/3Ta2/3O3 (BMT). The samples were prepared in two forms, viz. ceramics and single-crystal fibers, the latter were grown by laser heated pedestal growth technique (LHPG). All of these materials possess low dielectric constants, low losses and high Q values. In contrast to relaxor ferroelectrics, that as a rule exhibit broad features in their Raman spectra, SAN, SAT and especially BMT have very narrow phonon lines in the Raman spectra. A linear correlation is found between the microwave dielectric losses and the width of first order phonon lines in a sequence of BMT → SAT → SAN ceramics with increasing phonon damping. Moreover, the phonon damping decreases in materials with non-close-packed structure where there is enough space for undisturbed phonon vibrations. The problem of charge compensation in compounds with the Bsite disorder is also discussed.
Novel Technique for Measuring Through-Plane Thermo-Mechanical Properties of Thin Polymer Films
Authors: Patel K. S. , bidstrup-Allen Sue Ann , Kohl P. A. , HODGE T. C. 
Published: April 2011

ABSTRACTPolymer thin films (less than 20 ltm) are widely used as coatings and inter-level dielectrics in microelectronic applications. In multi-layer structures, stresses generated in the films due to interaction with adjacent layers and solvent evaporation induced shrinkage, cause the polymer chains to orient in the plane of the film resulting in anisotropic film properties. Characterization of properties in all directions is essential for accurate electrical and mechanical design and modeling.A new technique has been developed to measure, in-situ, the through-plane (z) properties of thin polymer films. A parallel plate capacitor device and an interdigitated electrode structure were used as sensors to detect changes in dielectric constant and thickness of thin polymer films under thermal or mechanical loading. The through-plane compression modulus and coefficient of thermal expansion were calculated and results are reported for benzocyclobutene (BCB) films.
Plasma etching of organic low-dielectric-constant polymers: comparative analysis
Authors: Baklanov M. R. , Vanhaelemeersch S. , Alaerts C. , Maex K. 
Published: April 2011

ABSTRACTThe etch characteristics of the low-k dielectrics DVS BCB (BCB hereafter) and SILK in oxygen/fluorine plasmas are studied. In an O2/NF3 plasma afterglow, the etch rate of both polymers first increase linearly with increasing NF3 concentration, then decreases monotonously. A fluorine plasma afterglow does not etch either BCB nor SILK but strongly changes their chemical and optical properties. Reactive ion etching (RIE) of the polymers shows a different behaviour. The etch rate of SILK in a pure oxygen plasma is maximal, but BCB is etched slowly. The fluorine additives increase the etch rate of BCB. The etch rate of SILK decreases with increasing fluorine concentration. RIE in a pure SF6 plasma shows good etch characteristics and can be used for some practical applications. Mechanisms of the reactions are discussed.
Plasma Etching of Hydrogen-Silsesquioxane
Authors: Liu Youfan , McMillan Chris , Dall Fred 
Published: April 2011

ABSTRACTCF4 plasma etching of hydrogen-silsesquioxane films on bare silicon substrates was conducted. An increase in average etching rate and a decrease in dielectric constant from 2.9 to 2.7 were observed after a top layer was removed from the surface of the film, indicating that a negative density depth gradient in the film was developed during the cure processing, A small part of the reduction in dielectric constant may be attributed to structural change resulting from the plasma interaction with the films since a small amount of Si-F bonds were identified in the surface layer of the film after plasma etching. There are indications in the x-ray photoelectron spectroscopy (XPS) spectra that traces of fluorocarbon polymer residue have been generated during the plasma etching. The results of this study also indicate a possibility of obtaining a lower dielectric constant HSQ film by plasma etching.
Integration Studies of Plasma Deposited Fluorinated Amorphous Carbon
Authors: Mountsier Thomas W. , Samuels John A. , Swope Richard S. 
Published: April 2011

ABSTRACTRecently, we reported the deposition of fluorinated amorphous carbon (FlAC) from hexafluorobenzene (C6F6) under parallel plate (PP) and inductively coupled plasma (ICP-HDP) conditions. Based on initial materials testing, these two platforms generated comparable materials with low dielectric constants (2.4 – 2.8), low weight loss/shrinkage (< 1.5 %/hr. at 425° C), hardness (2–3 Gpa) and adhesion (4–9 kpsi). Here we attempt to answer a basic integration question: FIAC compatibility with other materials used in the interconnect scheme. Investigations of adhesion of F1AC to, and capped by, silicon oxide, silicon nitride and various metals shows generally greater stability of the ICP generated material vs. PP-FIAC. Failures appeared to occur primarily at the FIAC/film interface at 400 and 300 °C for ICP and PP respectively. Although thickness-loss and weight-loss measurements indicate good thermal stability, TDS spectra show low-level outgassing of fluorine-based molecules and fragments even in samples annealed for 4 hours at 400 °C, resulting in interface failures. Plasma treatments and anneals of the F1AC were found to have a minimal effect but liner/cap composition and processing has a strong influence on the adhesion of other films to the fluorocarbon.
Liquid-Phase Deposition of Low-K Organic Silicon-Oxide Films
Authors: Usami K. , Sugahara S. , Sumimura K. , Matsumura M. 
Published: April 2011

ABSTRACTLow-K silica films were grown from the liquid phase using methyl-triethoxy-silane. Physical and chemical properties were investigated together with electronic properties. The film had dense methyl groups and showed insulating characteristics even under as-grown conditions. The dielectric constant, low-field resistivity and breakdown field-strength were 3.6, 1013 Ωcm and IMV/cm, respectively, for the as-grown film. They were improved to 2.6, more than 1015 Ωcm and more than 3MV/cm, respectively, after 300°C vacuum annealing
Electrical Reliability of Cu and Low-K Dielectric Integration
Authors: Wong S. Simon , Loke Alvin L. S. , Wetzel Jeffrey T. , Townsend Paul H. , Vrtis Raymond N. , Zussman Melvin P. 
Published: April 2011

ABSTRACTThe recent demonstrations of manufacturable multilevel Cu metallization have heightened interest to integrate Cu and low-K dielectrics for future integrated circuits. For reliable integration of both materials, Cu may need to be encapsulated by barrier materials since Cu ions (Cu+) might drift through low-K dielectrics to degrade interconnect and device integrity. This paper addresses the use of electrical testing techniques to evaluate the Cu+ drift behavior of low-K polymer dielectrics. Specifically, bias-temperature stress and capacitance-voltage measurements are employed as their high sensitivities are well-suited for examining charge instabilities in dielectrics. Charge instabilities other than Cu+ drift also exist. For example, when low-K polymers come into direct contact with either a metal or Si, interface-related instabilities attributed to electron/hole injection are observed. To overcome these issues, a planar Cu/oxide/polymer/oxide/Si capacitor test structure is developed for Cu+ drift evaluation. Our study shows that Cu+ ions drift readily into poly(arylene ether) and fluorinated polyimide, but much more slowly into benzocyclobutene. A thin nitride cap layer can prevent the penetration.
Polymer/metal Interfaces in Interconnect Structures: Moisture Diffusion and Stress Corrosion Effects
Authors: Ma Qing , Tran Quan , Pan Chuanbin , Fujimoto Harry , Chiang Chien 
Published: April 2011

ABSTRACTMoisture can cause a host of reliability problems at interfaces including interface debonding. Two mechanisms can be identified. First, moisture at an interface can reduce the interface bonding strength dramatically by altering the chemical bonds. Second, when an interface with a crack or a crack-like defect is under tensile stresses, stress corrosion may allow crack growth at stresses much lower than critical fracture would require. To avoid wet interfaces, wafers should be briefly baked or exposed to a plasmain situbefore the next film deposition step. However, moisture can also reach interfaces by diffusion along interfaces from unprotected edges during a wet process, such as CMP, or during storage in the ambient. In this work, the effect of moisture induced interface strength reduction was utilized to determine the diffusion distance. By using a mechanical peel technique, the diffusivity of moisture along the interface between Al and a poly(arylene ether) based low-K material (PAE2) was measured to be 4–6 μm2/s. Stress corrosion was studied using a special 4-point bend technique so that both strain energy release rate and crack velocity can be obtained. It was found that the mechanism of stress corrosion at this interface is more complicated compared to that in a bulk material: while the chemical reaction took place at the crack tip, moisture diffusion was also occurring along the interface ahead of the crack tip, preconditioning the interface. There appeared to be a region that kinetics was limited by interfacial moisture diffusion and reaction, from which the reaction time for interface weakening was estimated to be ∼ 10 seconds. It was also found that even for samples saturated with moisture, the relative humidity of the test environment was still very important.
Properties Development During Curing of Low Dielectric-Constant Spin-On Glasses
Authors: Cook Robert F. , Liniger Eric G. , Klaus David P. , Simonyi Eva E. , Cohen Stephan A. 
Published: April 2011

ABSTRACTVariations in the electrical and mechanical properties of silsesquioxane spin-on glass thin films are examined as a function of curing time and temperature. Particular attention is paid to the trade-off between producing low dielectric constant films, suitable for advanced microelectronic interconnection structures, and mechanically stable films, able to withstand semiconductor wafer fabrication processes. Two critical aspects of the mechanical stability of spin-on glasses are shown to be: the positive thermal expansion mismatch with silicon–leading to tensile film stresses; and reactivity with water–leading to susceptibility to stress-corrosion cracking.
Electromigration Study of Ai/Low K Dielectric Line Structures
Authors: Wang P.-H. , Pellerin J. G. , Fox R. J. , Ho P. S. 
Published: April 2011

ABSTRACTElectromigration reliability is a key concern for implementation of low dielectric constant (k) materials for on-chip interconnects. To address this problem, we have carried out a comparative study of electromigration performance for Al(0.5 wt% Cu) line structures formed with TEOS-based SiO2 and a low k polymeric material, poly(arylene ether) (PAE). The test structures consist of 800 μm long single-level ines. Resistometric measurements were performed to determine electromigration lifetime. To supplement lifetime measurements, TEM was used to measure overall grain size and electron back-scatter diffraction (EBSD) was employed to determine the local grain orientation and grain boundary characteristics in the line structure. In addition, SEM was used to examine void morphology. Microstructural analysis revealed a larger grain size and an enhanced (111) texture in PAE-passivated lines compared to TEOS-passivated lines. The differences can be attributed to a high-emperature process used to cure the PAE dielectric. The overall results obtained in this study show reasonably good electromigration performance for low k dielectric interconnects.
Carrier relaxation and recombination in InGaN/GaN quantum heterostructures probed with time-resolved cathodoluminescence
Authors: Zhang Xingang , Rich D. H. , Kobayashi J. T. , Kobayashi N. P. , Dapkus P. D. 
Published: April 2011

ABSTRACTSpatially, spectrally, and temporally resolved cathodoluminescence (CL) techniques have been employed to examine the optical properties and kinetics of carrier relaxation in InGaN/GaN heterostructure and single quantum well (QW) samples. CL images of the QW sample revealed a spotty cellular pattern indicative of local In compositional fluctuations on a scale of < 100 nm. The compositional variations induce local potential fluctuations, resulting in a strong lateral excitonic localization at InN-rich regions in the InGaN QW layer. Time-resolved CL measurements revealed a lateral spatial variation in the luminescence decay time which correlates with the spatial variation in the luminescence efficiency. A reduced lifetime is observed at boundary regions between centers of excitonic localization. A detailed time-resolved CL study shows that carriers generated in the boundary regions will diffuse toward and recombine at the InN-rich centers. An electron beam induced modification of the emission spectra was observed for InGaN/GaN heterostructure samples. Exposure to the e-beam resulted in a shift in the near-band gap emission to higher energies with a simultaneous increase in the emission intensity. These result are interpreted as a modification of the surface passivation through e-beam exposure and carbidization of the surface.
Electrical Stabilization of Diamond Mis Interface and Misfets by Ultrahigh-Vacuum Process
Authors: Yun Young , Maki Tetsuro , Tanaka Hiroyuki , Kobayashi Takeshi 
Published: April 2011

ABSTRACTIn order to obtain electrically stabilized MIS interface, a diamond metal-insulator- semiconductor field-effect transistor (MISFET) was prepared by means of reduced-oxygen process including ultrahigh-vacuum (UHV) process, and its electrical properties were closely investigated. According to the results, observed effective mobility (μeff) was 400 cm2/Vs at room temperature, which is the highest value obtained until now in the diamond FET at room temperature. The transconductance (gm) and surface state density (Nss) of the device operation region was 5mS/mm and ∼ 1010/cm2 eV, respectively, which is also comparable with conventional Si MOSFETs with the same gate length (Lg = 30μm).
Nitridation of Substrates With Hydrazine Cyanurate for The Growth of Gallium Nitride
Authors: Kropewnicki T. J. , Kohl P. A. 
Published: April 2011

ABSTRACTThe use of purified hydrazine cyanurate as a solid source of hydrazine in the low temperature nitridation of GaAs (100) and (111) and sapphire (0001) is demonstrated. Thenitridated surfaces were analyzed by X-ray Photoelectron Spectroscopy (XPS) for chemical composition and Atomic Force Microscopy for surface morphology. The GaAs surfaces were composed primarily of GaN, GaAs, and Ga2O3, and were as smooth as unprocessed standards. The nitridated sapphire surfaces were composed of A1NxO1-x and exhibited three-dimensional growth for long nitridation times.
Studies On The Intermetallic Semiconductor RuAl2
Authors: Ponnambalam V. , Varadaraju U. V. 
Published: April 2011

ABSTRACTThe intermetallic compound RuAl2 with Nowotny chimney-ladder structure is synthesized using arc melting technique. The electrical resistity and thermo electric power measurements were carried out in the temperature range 300–1000K. The resistivity increases with increasing temperature and reaches a maximum value at about 700K. Thermo electric power (TEP) of the sample is negative and the value is about -80 µV/K at RT. The value increases with increasing temperature reaching a maximum value of -140 µV/K at about 600K. The compound exhibits temperature independent power factor in the temperature range 300–550K The calculated figure of merit 1.3 × K-1 is comparable to 7 × 10-4 K-1 of Si-Ge alloys which are used as high temperature thermoelectric materials.
Transient Photoconductivity of GaN Thin Film On Sapphire Substrate
Authors: Chen Z. Z. , Shen B. , Zhang R. , Zhang X. Y. , Yang K. , Chen H. , Chen P. , Zang L. , Zhou Y. G. , Zheng Y. D. , Wu Z. S. , Sun X. T. , Chen F. 
Published: April 2011

ABSTRACTWe studied the transient photoconductivity(PC) properties of GaN thin film on (0001) sapphire substrate. The decay curves of PC obtained by YAG:Nd pulsed laser are divided into two special regions, which are the beginning and tail decay regions, corresponding to two time constants, 0.1 ms and 1.0 ms, respectively. Keeping the same light intensity and bias voltage, when the sample was heated to 300°C, the time constants are both reduced. It shows that there are a large number of traps at the position of tens of meV above the valence band edge. The PC ascends S-shaped when the data were collected during the first 200 ns. As the sample is not shined, the PC sharply reduces and oscillates, indicating that the carriers redistributed between the deep traps and the valence band. The experiment results are explained by the model that involves two hole trapping levels, the shallow trapping level and the deep trapping level. Moreover, the mechanism of the curves varied as the light intensities are also explained by the model.
Incorporation Of Er Into GaN By in-situ Doping During Halide Vapor Phase Epitaxy
Authors: Zhang Rong , Kuech T. F. 
Published: April 2011

ABSTRACTThe incorporation of Er into GaN by in-situ doping during halide vapor phase epitaxy has been investigated. The NH3, HCl, metallic Ga and Er were used as source materials, while N2 was employed as a carrier gas. The GaN:Er films were obtained at different Ga/Er source temperatures. The SIMS analysis shows that the steady state Er doping concentration can be as high as 2×1018 cm−3. All in-situ Er-doped samples luminescence at 1.54 μm due to the 4I13/2 → 4I15/2 transition of Er3+ at both low (11K) and room temperature. The higher the Ga/Er boat temperature, the stronger the 1.54 μm luminescence, implying a higher incorporation rate of Er into the GaN. The 4I11/2 → 4I15/2 transition luminescence, centered around 980 nm, can also be detected at both low and room temperature. The broad-spectrum PL measurements exhibited sharp bandedge luminescence without the presence of the yellow luminescence band.
The Effect of Thermal Annealing of Au Contacts on 6h-Sic and 4h-Sic
Authors: Shi D. T. , Lu W. , Chen H. , Collins W. E. 
Published: April 2011

ABSTRACTThe annealing effects of gold contacts on SiC single crystal substrates have been investigated using SPM and XPS/AES. Ultra-thin Au films with thicknesses of 30 Å and 150 Å, respectively, were fabricated onto both 4H- and 6H-SiC substrates via rf sputtering. The Au/SiC systems were then undergone a series of annealing with temperatures ranging from 200 °C to 400 °C. This study reveals that the sputtering system can generally produce a thin film of uniformly distributed nano-meter sized granular particles. The size of the particles increases with both the thickness of the ultra-thin film and annealing temperature. The thicker Au film revealed pin-hole damages after 300 °C annealing and severe cracking and spalling after 400 °C. However, the thinner Au film only demonstrated the increase of particle sizes. The atomic ratio of gold to silicon in the surface region decreases with the increase of annealing temperature, which indicates the diffusion of gold into silicon carbide. No significant changes of the Schottky barrier heights have been found for Au contacts onto both 6H- and 4H-SiC in the annealing temperature range. After the 400 °C annealing, a noticeable SiO2/SiOx, peak was unveiled in the XPS spectra.
X-Ray Photoemission Spectromicroscopy Of Gan And AIGan
Authors: Lorusso G. F. , Solak H. , Cerrina F. , Underwood J. H. , Batson P. J. , Kim Y. , Cho Y. , Kisielowski C. , Krueger J. , Weber E. R. 
Published: April 2011

ABSTRACTWe investigate here for the first time GaN and AIGaN films by using x-ray photoemission spectromicroscopy. As compared to conventional x-ray photoemission spectroscopy (XPS), spectromicroscopy can provide spatially resolved information on the chemical composition of the sample surface. The experimental results where obtained by using MAXIMUM, a scanning photoemission microscope installed on 12.0 undulator beamline at the Advanced Light Source (ALS), Berkelely, allowing for a spatial resolution of 100 nm. We investigate here GaN and AlGaN thin films grown on sapphire substrate by metalorganic chemical vapor deposition (MOCVD). The results clearly indicate the great potential of spectromicroscopy in investigating chemical inhomogeneity, inpurities and localization in GaN and AlGaN thin films.