bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Properties of a Plasma Deposited Candidate Insulator for Future Multilevel Interconnects Technology.
Authors: Gelatos A. V. , Mogab C. J. , Saha N. C. , Parikh N. 
Published: March 2011

ABSTRACTResults are reported from an investigation of the properties of boron nitride thin films. The BN films were deposited by the method of plasma enhanced chemical vapor deposition (PECVD) from mixtures of ammonia and diborane. The deposition variables were RF power, pressure, ammonia partial pressure, diborane partial pressure, diluent type (nitrogen or argon), and temperature. The films were characterized for their stoichiometry, hydrogen content, stress, refractive index, and especially for their dielectric properties. It was observed that the main parameters affecting the dielectric constant were the ratio of ammonia to diborane flow, and the deposition temperature. The dielectric constant decreased with increasing ammonia to diborane ratio, while it increased with decreasing deposition temperature. The lowest dielectric constant value achieved was 4.0 ·, 0.1. Nitrogen dilution allowed the deposition of boron nitride films with the lowest dielectric constant value at ammonia to diborane ratios smaller than those required under argon dilution, which suggests some incorporation of nitrogen into the boron nitride matrix from the diluent.
Doping and beyond: towards a common model for the ohmic contact formation mechanism in the Au/Te/Au/-, AuGe/-, and Ge/Pd/n-GaAs systems
Authors: Wuyts K. , Watté J. , Silverans R. E. , MüNder H. , Berger M. G. , Luth H. , Van Hove M. , Van Rossum M. 
Published: March 2011

ABSTRACTThe results of our recent research on the ohmic contact formation mechanism in furnace alloyed Au/Te/Au/GaAs contacts are summarized, and preliminary Raman measurements on annealed Ge/Pd/GaAs structures are presented. The data and those reported in literature on the AuGe- and Ge/Pd- GaAs systems are argued to be more in agreement with the graded crystalline heterojunction concept (the formation of n+-Ge/GaAs, n+Ga2Te3/GaAs junctions) than with the doping model (the formation of n+-GaAs).
Lognormal Lateral Distribution of Barrier Height in Au/n-GaAs Schottky Junctions?
Authors: Horváth ZS. J. 
Published: March 2011

ABSTRACTExperimental capacitance-voltage (C-V) characteristics are presented for Au/n-GaAs Schottky contacts. The deviation of the obtained C-V characteristics from the theoretical one including the linear regions of the 1/Ca-V plot may be explained by either the normal or the lognormal lateral distribution of the barrier height. It is concluded that from physical point of view the lognormal lateral distribution of the Schottky barrier height proposed first in this work, is more likely than the normal distribution.
Fabrication of Hollow High Aspect Ratio Metal Microstructure Arrays
Authors: Calvert J. M. , Georger J. H. , Rebbert M. L , Anderson M. A. , Park D. , Hickman J. J. , Dulcey C. S. , Peckerar M. C. 
Published: March 2011

ABSTRACTA process has been developed to produce regular arrays of hollow metal microstructures on substrates of choice. Optical lithography was used to define high aspect ratio structures in photoresist. The resist structures were selectively metallized by electroless (EL) deposition such that metal was deposited only on the sidewalls of the resist and on the surface of the substrate. Dissolution of the polymeric photoresist resulted in regular arrays of hollow metal cylinders and cones with geometries and structure spacings determined by the original resist structures. Characterization of metallized microstructures using surface analytical techniques and SEM is presented. Arrays of microstructures with 500–1000 Å thick EL Ni walls and aspect ratios (height/tip diameter) of 8:1 are shown.
Stability of Nanoscale Cobalt Silicide Film Formation on Polysilicon
Authors: Pramanick S. , Erokhin Yu. N. , Patnaik B. K. , Rozgonyi G. A. , Gambino J. P. 
Published: March 2011

ABSTRACTWe have extended the recent work1,2 on grain boundary grooving, agglomeration and islanding during the reaction of thin Co films on single crystal Si<100> substrates (source/drain contacts) to the case of poly silicon substrates3 (gate contact and local interconnects). The stability of 27 to 50 nm CoSi2 films formed via rapid thermal annealing on polysilicon substrates with and without P+ or Ge+ implantation was examined using XTEM, RBS, XRD, and Four-probe measurements. For an undoped polysilicon, partial agglomeration of a 30 nm CoSi2 film has been observed, similar to that seen on a single crystal Si substrate.2For heavily Phosphorus doped polysilicon, a transition from low resistance, stoichiometric cobalt disilicide films (700 °C, 10 sec RTA) to high resistance films at 700 °C, 30 sec RTA (600–1000 Ω per square and discontinuous suicide grain growth) has been observed. Concurrent suicide formation on preamorphized polysilicon (Ge+ I/I and no anneal) has been found to suppress agglomeration of nanoscale cobalt suicide layers, since small grain size and low grain boundary energy are favorable for improving thermal stability4. These continuous layers also exhibited the lowest sheet resistance corresponding to a resistivity of ≤ 21 μΩ-cm.
Effect of Near-Interface Concentration Change on Barrier Height in Ion-Bombarded and Heat-Treated GaAs Schottky Contacts
Authors: Horváth ZS. J. 
Published: March 2011

ABSTRACTThe change of the doping concentration (including type) near the metal-semiconductor interface influences the Schottky barrier height (BH). In many cases this phenomenon is apparently spontaneous, or it is a side effect of the technology. The goal of this paper is to summarize the effect of the near-interface concentration change on the apparent and real Schottky BHs, and to demonstrate its importance with experimental results obtained in GaAs Schottky contacts. The question of the definition of the real BH for some of these structures is also treated.
Optimizing n+ Ohmic Contacts on GaAs for HemtS
Authors: Harris H. M. , Farley J. R. 
Published: March 2011

ABSTRACTLow ohmic contact resistance is essential for high performance microwave and millimeter wave transistors. Rapid thermal processing (RTP) has been used to optimize the ohmic contact resistance of gold - germanium / nickel / gold metallizations on gallium arsenide (GaAs) layers for high electron mobility transistor (HEMT) applications. A HEMT layer structure consisting of a 9000Å buffer layer grown on a semi-insulating substrate followed by a 20Å undoped AlGaAs spacer layer, a 700Å Al0.22Ga0.78 As layer doped at 1.0 × 1018cm-3and a 500Å GaAs cap layer doped at 1.5 × 1018 cm°C to 450°C. Time at temperature was varied from 10 seconds to 1 minute. Optimum conditions for our equipment and layer structure were found to be 365°C for 30 seconds. These conditions produced contact resistances of 0.08 ohm-mm (approximately 2.0 times better than the standard furnace alloy process).
The Ternary Phase Diagram for Au-Ga-As Using the Flow Chart Technique
Authors: Mueller C. H. , Holloway P. H. , Connell R. G. 
Published: March 2011

ABSTRACTDegradation of the Au/GaAs interface during heating is a problem which limits device reliability. The “flow chart” method was used to construct the ternary Au-Ga-As phase diagram and determine the equilibrium reactions which are responsible for interfacial degradation. Interfacial degradation was correlated with the removal of Asx from the interface, which lowered the liquidus temperature and enhanced the dissolution of GaAs. The dissolution proceeds by a series of class II reactions within the Au-AuGa-GaAs ternary system and results in the incorporation of Ga into the Au phase, and growth of several AuxGay phases. However, when the processing is accomplished in a manner which prevents the interface from being depleted in As, no interfacial degradation is expected.
Metallurgical Behavior of the Metal-IN-P Systems: Implications for the Design of Contacts to Inp
Authors: Mohney Suzanne E. , Austin Chang Y. 
Published: March 2011

ABSTRACTPhase equilibria in the M-In-P (M = transition metal) ternary systems is determined through a combination of thermodynamic calculation and experimentation. Palladium is identified as a particularly attractive metal for contacts to InP. One useful feature of this system for contact design is the occurance of PdχInP ternary phases. Additionally, Pdln is found to be in equilibrium with InP and is identified as a promising contact material to InP because of its high melting point, low resistivity, and favorable properties for processing. Progress in the development of Pdln-based contacts to InP is briefly discussed.
Au/Ge/Pd Ohmic Contacts to n-TYPE InP
Authors: Jian Ping , Ivey Douglas G. , Bruce Robert , Knight Gordon 
Published: March 2011

ABSTRACTOhmic contact formation and thermal stability in a Au/Ge/Pd metallization to n-type InP, doped to a level of 1017 cm-3, have been investigated. Contact resistance was measured using a transmission line method, while microstructural changes were examined by means of TEM, EDX, CBED and SAD. Contacts became ohmic after annealing at temperatures ranging from 300°C to 375°C. A minimum contact resistance of 2.5×l0-6 Ω-cm2 was obtained after annealing at 350°C for 320s. The drop in resistance to ohmic behavior corresponded to the decomposition of an epitaxial quaternary phase (Au-Ge-Pd-P). Annealing at 400°C and above resulted in Au10In3 spiking into InP and a break down of contact lateral uniformity, which increased contact resistance.
The Achievement of Low Contact Resistance to Indium Phosphide: the Roles of Ni, Au, Ge, and Combinations Thereof
Authors: Fatemi Navid S. , Weizer Victor G. 
Published: March 2011

ABSTRACTWe have investigated the electrical and metallurgical behavior of Ni, Au-Ni, and Au-Ge-Ni contacts on n-InP. We have found that very low values of contact resistivity (pc) in the E-7 Ω-cm2 range are obtained with Ni-only contacts. We show that the addition of Au to Ni contact metallization effects an additional order of magnitude reduction in pc. Ultra-low contact resistivities in the E-8 Ω-cm2 range are obtained with both the Au-Ni and the Au-Ge-Ni systems, effectively eliminating the need for the presence of Ge in the Au-Ge-Ni system. The formation of various nickel phosphides at the metal-InP interface is shown to be responsible for the observed pc values in the Ni and the Au-Ni systems. We show, finally, that the order in which the constituents of Au-Ni and Au-Ge-Ni contacts are deposited has a significant bearing on the composition of the reaction products formed at the metal-InP interface and therefore on the contact resistivity at that interface.
Physical AMD Electrical Properties of Iridium Thin Films
Authors: Elliman R. G. , Lawn M. A. , Reeves G. K. , Jagadish C. 
Published: March 2011

ABSTRACTThin Ir films were deposited onto clean (111) Si surfaces. The films were analysed by Rutherford backscattering and transmission electron microscopy and were shown to be continuous for film thicknesses as small as 0.5nm. The films contained internal stress as deposited and coiled up when the substrate was removed chemically.A four point probe was employed to measure the resistivity of the films as a function of film thickness. The resistivity increased with decreasing film thickness, from ∼35 micro-Ohm. cm for 160nm thick films to -190 micro-Ohm. cm for 0.5nm thick films. This increase in resistivity is shown to be consistent with theories of carrier transport in thin films.
Advanced Planarized Aluminum Metallization Process
Authors: Chen F. S. , Durit G. A. , Staman J. W. , Wei C. C. , Liou F. T. 
Published: March 2011

ABSTRACTSputtered aluminum has been used for interconnection in integrated circuits because of its low resistivity. However conventional sputtered aluminum has two important drawbacks, poor step coverage and poor planarization, which make it unsuitable for eubmicron multi-level interconnect process. CVD tungsten is an attractive option for forming plugs and interconnects but suffers several drawbacks. It is therefore preferable to use aluminum for both plugs and interconnections due to its simplicity and established prior history. We have developed a fully planarieed aluminum metallization process which produces void free contact plugs.In order to verify the filling of the contact plugs, we have carried out extensive SEM analysis using secondary electron and backscattered electron imaging methods with various SEM sample preparation methods, i.e. chemical etching to extract the metal plug without inducing any damage to the metal, SEM cross section prepared with some oxide (about 1000Å) left in front of the metal plug and standard SEM cross section through the metal plug. Complementary secondary and backscattered imaging has proven to be a reliable method for ascessing the filling of the contact holes. Wafer and package level reliability data for the planarized aluminum metallization used on a megabit device will also be presented.
The Volatile Component Loss and the Surface Morphology of the Gold-Palladium Metallizations to the Compound Semiconductor Structures
Authors: Dobos L. , Kovács B. , Mojzes I. , Malina V. , Pécz B. , Karányi J. 
Published: March 2011

ABSTRACTPalladium based metal systems can be used to make ohmic contacts to AIIIBV compound semiconductors. A covering layer of gold is advantageous even from the point of view of bonding. Gold, palladium, Au/Pd layers were studied on InP and GaAs substrates. The samples were annealed in the vacuum chamber of the scanning electron microscope (SEM) and the volatile component losses (arsenic or phosphorus) were monitored by a quadrupole mass spectrometer. The changes of the surface morphology were studied using the SEM images. In the case of Pd/AIIIBV samples a single characteristic peak due to the interaction taking place between the palladium and the substrate was observed on the volatile component loss vs. temperature curve. In the case of Au/Pd/AIIIBv samples a second peak appeared on the evaporation vs. temperature curve due to the interaction between gold and AIIIBV substrate. The temperature of that second peak is about 50–60°C higher than in the case of a single gold layer on AIIIBV substrates because gold had to diffuse through the palladium layer, what hindered the reaction of gold with AIIIBV materials.
Interconnection Challenges of the 1990'8
Authors: Fury Michael A. 
Published: March 2011

ABSTRACTSilicon device performance has improved dramatically over the past two decades. During that time, the portion of total circuit delay attributable to interconnect wiring has increased to nearly half. Changes in the use of aluminum wiring and silicon oxide insulators must be considered to further improve performance.The generation of ULSI circuitry now under development in the industry depends heavily on innovations in materials and processes to achieve significant improvements in wiring density and circuit performance. The subsequent generation places even greater demands on materials improvements for lower resistivity wiring and a lower dielectric constant insulator. Integrating materials and methods compatible with semiconductor processing while ensuring device reliability will create a significant financial challenge in addition to the technical challenge.This presentation enumerates the interconnection challenges facing the materials scientist and the circuit designer. The ultimate limits in materials improvements are predictable and finite. Further improvements will be derived from design innovations such as treating interconnects as active rather than passive devices. Accurate physical modelling of MLM structures will complement even more complex electrical modelling. Manufacturing sciences will grow in sophistication if implementation is to succeed. The financial burden of these technical challenges will foster collaborations among semiconductor manufacturers, equipment vendors, and research universities.
Experimental Design Study of Coincident Titanium Nitride/Titanium Silicide Formation from Rapid Thermal Processing
Authors: O'Meara D. L. , Spero J. C. 
Published: March 2011

ABSTRACTAn experimental design method was used to define the process behavior of the two barrier metal properties most applicable to semiconductor device fabrication: contact resistance and contact junction current leakage. Instead of using basic research-level evaluations such as sfoichiomefry and film composition, we attempt to optimize titanium nitride (TiN) barrier metal properties to obtain both low contact resistance and low contact junction current leakage. The optimization was based on TiN films made using a rapid thermal process (RTF).Our study focussed on TiN barriers formed on arsenic-doped n-type contacts. A two-step thermal process was used with temperature and duration of each step and the initial titanium thickness chosen as process variables. Response surface modeling of the contact resistance and contact junction leakage current reveals response variations that suggest three regions of film formation. The model defines an optimum barrier metal process to minimize both contact resistance and current leakage for the arsenic-doped contacts used for this study.
Enhanced Pteos and O3-Teos CVD Processes for Improved Step Coverage and Gap-Filling
Authors: Ghosh Sumanta K. , Bourgeois Mark A. , Ramkumar K. , Saxena Arjun N. 
Published: March 2011

ABSTRACTThe step-coverage and gap-filling characteristics of SiO2 films deposited by TEOS based plasma CVD and Thermal CVD processes on AlX and Cu/X metallizations were studied. It was found that the conformality of the films, in the case of plasma CVD, is influenced by the relative flow rates of TEOS to oxygen. The suitability of the two types of SiO2 films for filling gaps of different aspect ratios on AlX and Cu/X metallizations with different aspect ratios was examined. The results are discussed and correlated with the other important characteristics of these SiO2 films.
Selective Metallization of CVD Diamond Films
Authors: Calvert J. M. , Pehrsson P. E. , Dulcey C. S. , Peckerar M. C. 
Published: March 2011

ABSTRACTA process has been developed for the deposition of patterned adherent metal on diamond substrates using low temperature processing conditions. CVD diamond films on Si wafers were oxidized with an RFO2 plasma and subsequently functionalized by attachment of self-assembled ultrathin films (UTFs) to the oxidized diamond surface. The UTFs were exposed to patterned deep UV radiation, and selectively metallized by electroless (EL) deposition. EL Ni and Co patterns, with feature sizes to 20 μm linewidth have been produced. Oxidized and UTF-modified surfaces were characterized by surface spectroscopie and wettability techniques. The EL metal deposits on the diamond substrate passed the Scotch tape adhesion peel test.
Thermal Studies of Au-Ti Thin Films Deposited on Oxide Substrates
Authors: Strane J. W. , Russell S. W. , Li Jian , Mayer J. W. 
Published: March 2011

ABSTRACTCo-evaporated Au-Ti thin films deposited onto sapphire and silicon dioxide substrates were thermally treated over a temperature range of 300–900°C in both vacuum and reactive amb ients. Vacuum annealing produced negligible reaction between the oxide substrate and film, the Au-Ti, however, reacted to form intermetallic compounds with little net elemental redistribution in the film. Heat treating in oxygen resulted in segregation of titanium to the surface where it formed both rutile and anatase structures. In addition, the high interfacial energy between the gold and the oxide phases led to the formation of large (5 micron diameter) gold particles on the film surface or voids at the titania-gold interface. Annealing in Ammomia produced an oxynitride surface in addition to the Ti-Au separation, Au particulate formation, and/or interfacial voiding already observed. The extent of surface degradation observed during these reactive ambient anneals varied with Ti concentration and temperature. The film did not react with SiO2 under any circumstances, however, at temperatures above 650°C in reactive ambients the titanium accumulated at the Al2,O3 interface. These results were obtained by RBS, X-ray diffraction, TEM and SEM.
Kinetics of Intermetallic Formation in Free Standing Cu/Mg Multilayer Thin Films
Authors: Arcof B. , Clevenger L. A. , Murarka S. P. , Harper J. M. E. , Cabrai C. 
Published: March 2011

ABSTRACTDifferential scanning calorimetry (DSC) has been used to study the temperatures, kinetics and phase formation mechanisms in Cu/Mg multilayer thin films. When the Cu:Mg layer thickness ratio was 1:4, CuMg2 was the only phase that formed. Cu/Mg films with a layer thickness ratio of 1:1 first form CuMg2 at 215°C with an activation energy of 1.0 ± 0.04 eV and then Cu2Mg at 380°C with an activation energy of 0.73 ± 0.04 eV. The temperatures at which the two phases form decrease as the layer thicknesses decrease due to the shorter reaction times needed in thinner films. The constant scan rate DSC data from films with a layer thickness ratio of 1:1 show three exothermic peaks. The first peak is extremely sharp and results from the formation of isolated nuclei of CuMg2 at the Cu/Mg interface. The formation of CuMg2 is thus shown to be nucleation controlled. The second peak is a growth peak due to the heat released during the growth of CuMg2. The third peak corresponds to the formation and growth of Cu2Mg.
Space Charge Effects Due to Near Contact Non-Uniform Electric Fields in Semi-Insulating GaAs
Authors: Derhacobian Narbeh , Haegel Nancy M. 
Published: March 2011

ABSTRACTVariable length semi-insulating GaAs p+-υ-n+ diodes are used to investigate the influence of near contact electric field non-uniformities on the injection of minority carriers. The results show that despite the presence of highly linear IV characteristics, significant nonuniformities in the electric field dominate the device response. The current density through the device is shown to depend on the device length with a power law J ∞ (L)1.0 at a constant bias. The experimental results are compared, with good agreement, to a theoretical model which treats semi-insulating GaAs as a trap-dominated relaxation semiconductor. Electroabsorption measurements are used to observe the slow transients associated with the appearance of near contact field nonuniformities.
Evidence of Electrical Interactions between Photo-Induced Charge Carriers and Moving Dislocations in Red Mercuric Iodide
Authors: Marschall Jochen , Milstein Frederick 
Published: March 2011

ABSTRACTVariations in both the hole and the electron photocurrents in single crystals of mercuric iodide (HgI2) are measured during plastic deformation by shearing over (001) planes. The results demonstrate the presence of electrical interactions between moving “easy glide” dislocations and photo-induced charge carriers in HgI2. It is found that both hole and electron photocurrents are decreased during dislocation motion and that the extent of this effect (and the subsequent recovery after deformation ceases) depends on the applied bias.