bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Properties of Transition Metal Hydrogen Complexes in Silicon
Authors: Weber J. 
Published: April 2011

ABSTRACTA summary is given on the electrical properties of transition-metal hydrogen complexes in silicon. Contrary to the general understanding, hydrogen leads not only to a passivation of deep defect levels but also creates several new levels in the band gap due to electrically active transition-metal complexes. We present detailed data for Pt-H complexes and summarize briefly our results on the transition metals Ti, Co, Ni, Pd, and Ag. The introduction of hydrogen at room temperature by wet chemical etching, followed by specific annealing steps allows us to study the formation of the different complexes. In particular, depth profiles of the defect concentrations give an estimate of the number of hydrogen atoms involved in the complexes. Transition-metals binding up to four hydrogen atoms are identified.
Hydrogen-induced Changes of The Microscopic Structure of Microcrystalline Silicon
Authors: Kaiser I. , Nickel N. H. , Pilz W. , Fuhs W. 
Published: April 2011

ABSTRACTMicrocrystalline silicon samples were exposed to an electron cyclotron resonance (ECR) hydrogen plasma at various exposure times and substrate temperatures. Before and after each post-hydrogenation treatment the crystalline fraction, Xc, was determined from Raman backscattering spectra. The results reveal that the change of Xc strongly depends on the structural composition of the starting material. Amorphous samples exhibit an increase of Xc while for ltc-Si specimens the Xc decreases. The decrease of Xc is enhanced for specimens with a high initial crystalline fraction. The same plasma treatment of Si-wafers did not lead to amorphisation. We conclude that the presence of lattice strain is required to observe a H-induced decrease of Xc.
H-passivation of Si(100) By Wet Chemical Cleaning: Discovery of Ordering
Authors: Atluri V. , Herbots N. 
Published: April 2011

ABSTRACTSi(100) is H-passivated via a modified pre-RCA cleaning followed by etching in HF:alcohol, to produce ordered (1 × 1) templates which desorb at low temperature (T ≥ 600°C). Four sets of 12 wafers, each set processed identically, are used to test reproducibility, and are characterized by Ion Beam Analysis (IBA), Tapping Mode Atomic Force Microscope (TMAFM), and Fourier Transform Infrared Spectroscopy (FTIR). The absolute coverage of oxygen and carbon is measured by ion channeling combined with nuclear resonance at 3.05 MeV for oxygen and 4.265 MeV for carbon, improving the signal to noise by a factor 10 for oxygen and by 120 for carbon. It is then possible for the first time to measure ordering of oxygen atoms with respect to the surface by comparing the amount of oxygen from rotating random spectra to the disordered oxygen measured by channeling. Hydrogen is measured via the elastic recoil detection (ERD) of 4He2+ at 2.8 MeV.Si(100) etched in HF:methanol after a modified preliminary RCA cleaning yields the cleanest surface. The data suggest that Si(100) passivated by HF in alcohol is terminated by an ordered hydroxide layer, which desorbs at lower temperatures than the more refractory Si02.
Effect of Hydrogen on Surface of Niobium
Authors: Gadgil V. J. , Keim E. G. 
Published: April 2011

ABSTRACTNiobium single crystals are used as substrate material for constructing superconducting quantum interference device or SQUID. The use of niobium is prompted by the fact that it is a low Tc metallic superconductor. In order to fabricate the device the surface of the crystal has to be polished flat. This is achieved by combination of mechanical polishing and electrochemical polishing. It has been reported that during electrochemical polishing hydrogen can enter the material forming Niobium hydrides. These can result in surface roughening of a magnitude greater than the thickness of the films subsequently deposited. This leads to failure of the films. The problem can be solved by annealing the material at 300° C to remove any hydrogen that might be present. However it is phenomenologically interesting to study the effect of electrochemical hydrogen charging on the surface of Niobium.
Power Supply Distribution and Other Wiring Issues For deep-submicron Ic's
Authors: Lynch W. T. , Arledge L. A. 
Published: April 2011

ABSTRACTAn Interconnect Architecture Optimization (IAO) methodology is proposed. The algorithm makes use of fundamental RLCLL2 relations for wiring delays, as well as predictive 3D interconnect density function histograms with y and x axes of wire length and inverse gate delay. The fundamental RLCLL2 relations determine “maximum” wire lengths as a function of wiring size within the wiring hierarchy; the 3D histogram establishes the pre-physical design allocations of wiring nets within the hierarchy. The decision process begins with the set-asides of wiring for power, clock, and vias, and ends with an optimized number of wiring levels and sizes. Some of the major conclusions of the preliminary analyses are: there are no significant problems with wiring at the lowest level as long as the local wire lengths are appropriately scaled; the MOSFET device may not be able to provide enough current to satisfy the capacitive fanout loads within the future allocations of clock period; and the global wires, despite significant improvements in performance, will continue to provide a design and technology challenge for larger chips and higher frequencies.
Thickness Effects in the Reaction of Cobalt with Slicon-Germanium Alloys
Authors: Boyanov B. I. , Goeller P. T. , Sayers D. E. , Nemanich R. J. 
Published: April 2011

ABSTRACTThe thickness dependence of the reaction of cobalt with silicon and epitaxial silicongermanium alloys (SiGe) was studied. Cobalt layers 25 Å and thicker deposited on Si(100) and annealed at 600°C formed CoSi2. When the thickness of the Co film was reduced to 10 Å the Co/Si(100) reaction resulted in a mixture of CoSi and CoSi2 even after annealing for 20 minutes at 800°C. The products of the reaction of Co with (100)-oriented Si1−x Gex after annealing at 800°C depended on the thickness of the Co film and the Ge concentration in the SiGe layer. When the thickness of the Co film was below a critical value, the only phase formed during the Co/SiGe reaction was CoSi. A mixture of CoSi and CoSi2 was observed when the thickness of the Co film exceeded the critical value. The critical thickness for CoSi2 nucleation increased superlinearly with Ge concentration in the range 0≤x≤0.25, and did not depend on the doping of the Si(100) substrate or the strain state of the SiGe film. XRD and EXAFS measurements indicated no measurable incorporation of Ge had occurred in either the CoSi or CoSi2. The amount of CoSi2 formed above the critical thickness increased monotonically with the thickness of the as-deposited Co film. The observed thickness effect was attributed to preferential Co–Si bonding in the reaction zone, and was modeled in terms of the energy cost of Ge segregation, which accompanies the formation of CoSi and CoSi2 during the reaction of Co with SiGe.
Integration of NiSi SALICIDE for Deep Submicron CMOS Technologies
Authors: Lin X. W. , Ibrahim N. , Topete L. , Pramanik D. 
Published: April 2011

ABSTRACTA NiSi-based self-aligned silicidation (SALICIDE) process has been integrated into a 0.25 Ion CMOS technology. It involves rapid thermal annealing (RTA) of Ni thin films (300, Å thick) on Si substrates in the temperature range ≈400 - 700 °C. It was found that the NiSi sheet resistance (Rs) gradually decreases with decreasing linewidth. Parameters, such as RTA temperature, substrate dopant (As vs BF2) and structure (single crystal vs poly), were found to have little effects on Rs. NiSi forms a smoother interface with single crystalSi than with poly Si, and has a slightly lower resistivity. MOSFETs based on NiSi show comparable device characteristics to those obtained with Ti SALICIDE. Upon thermal annealing, NiSi remains stable at 450 °C for more than 39 hours. The same is true for 500 °C anneals up to 6 hours, except for NiSi narrow lines (<0.5 μm) on n+ poly Si substrates whose Rs is moderately increased after a 6 hr anneal. This work demonstrates that with an appropriate low-thermal budget backend process, NiSi SALICIDE can be a viable process for deep submicron ULSI technologies.
Growth and Characterization of Self-Aligned Erbium Silicide on N-Type, (100) Oriented Silicon
Authors: Das Suhit R. , LeBrun Les , Sproule G. Irwin 
Published: April 2011

ABSTRACTIn view of its low barrier height to n-type Si, ErSi2 has potential applications as an infrared detector, as low-resistance ohmic contacts and as source/drain regions in Schottky barrier MOSFETs. Although there is a substantial body of work on ErSi2 grown on Si(111), there are relatively few published papers on the growth and properties of ErSi2 on Si(100). In order to develop a CMOS-compatible process, we have studied the growth of ErSi2 using a multi-source, UHV magnetron system to sputter-deposit 20 nm Ti/(10–50) nm Er bilayers on chemically cleaned n-Si(100) substrates followed by ex-situ rapid thermal annealing in N2. Highly oriented ErSi2 in the hexagonal phase was formed at an annealing temperature of 400°C with ErSi2 (100) Si(100). The Ti overlayer and the unreacted Er were selectively etched in HF and HNO3, respectively, leaving behind an ErSi2 layer with a smooth surface morphology, a uniform bulk composition and a planar ErSi2/Si interface. Results of electrical sheet resistance and Schottky barrier height measurements on these layers will be reported.
Suppression of the Phase Transition and Agglomeration of TiSi2 by Addition of Zr Element
Authors: Yoon Sanghyun , Jeon Hyeongtag 
Published: April 2011

ABSTRACTThe formation of C49 TiSi2 phase at high temperatures was investigated by adding the Zr contents in Ti-silicide film. Stabilizing the C49 TiSi2 phase which exhibits lower surface and interface energies than those of the C54 TiSi2 phase at high temperatures was expected to suppress the problems of Tisilicide, such as the phase transition and the film agglomeration. The thin films of Ti and Zr were codeposited (40 nm) on Si substrates in the dual e-beam evaporation system equipped with an ion pump and its base pressure of ∼5 × 10−9 torr. The amounts of Zr contents (5 and 10 atomic %) added on Tisilicide were monitored by in-situ quartz crystal monitor. Immediately after the deposition, this film was annealed by ex-situ vacuum furnace at temperatures between 600 °C and 900 °C in 100 °C increments. The identification of the phase and the chemical composition were investigated by XRD and AES, respectively. The surface and interface morphologies were examined using cross-sectional TEM. The phase transition temperature of TiSi2 was raised with increasing Zr contents. The agglomeration of TiSi2 film was also suppressed by adding Zr element and much improved interface morphologies were observed.
New Approaches for Formation of Ultra-Thin PtSi Layers for Infrared Applications
Authors: Donaton Ricardo A. , Jin Sing , Bender Hugo , Zagrebnov Maxim , Baert Kris , Maex Karen , Vantomme Andre , Langouche Guido 
Published: April 2011

ABSTRACTPtSi is one of the most used silicides in infrared Schottky barrier detectors due to its low Schottky barrier to p-type Si ( Øb ∼ 0.23 eV). Control of the thickness and uniformity of the silicide layer is fundamental for a good infrared detector performance, since the silicide thickness has to be in the range of 3 to 8 nm. Such thin layers are usually made by evaporation of Pt followed by a furnace annealing. We will show different approaches for fabrication of utra-thin PtSi layers. In all of the processes, high-vacuum sputtering is used for Pt deposition and the silicidation is performed in a rapid thermal annealing system. Smooth and uniform Pt Si layers down to 3 nm thick are formed in this way. It will be shown that the controllability of the thickness during sputter deposition is not a critical issue and the deposition process has a large process window. Moreover, when taking an optimal approach, a large process window can also be found for the RTA step. The implementation of these approaches for device fabrication and some electrial results of diodes made with them will also be presented.
Homogenization of the Bilayers of Cu-Al Alloy and Pure Copper to Produce CU-0.3 at.% Al Alloy Films
Authors: Wang Pei-I , Murarka S. P. , Bedell S. , Lanford W. A. 
Published: April 2011

ABSTRACTPreparation of Cu-0.3 at.% Al alloy films by homogenization anneals of metallic bilayers consisting of Cu/Cu-AI on SiO2 is studied to produce advanced copper based metallization for future ICs. The bilayer films were annealed at temperature in the range of 200°C- 400°C and the depth profiles were obtained using Rutherford Backscattering technique. It is found that Al diffuses through the undoped copper layer to surface - leading to lower Al concentration in the original Al doped Cu layer and apparently increased concentration of Al in undoped Cu (not detectable by RBS). The resistivity of these annealed films ranged from 2.1 to 2.4 μΩ-cm depending on final Al concentration achieved. Electrical stability of such MOS capacitors was also investigated. All these results will be presented and discussed showing that Al-doped copper layers can be used as diffusion barrier/adhesion promoter between the oxide ILD and copper metal.
Ambient Dependence of Agglomeration Stability of Cu/Ta Films
Authors: Hartman J. W. , Atwater H. A. , Hashim Imran , Chin Barry , Chen Fusen 
Published: April 2011

ABSTRACTWe have investigated the effects of oxygen contamination on the agglomeration of thin Cu films fabricated by physical vapor deposition on Ta barriers. Thin Cu films on clean, ultrahigh vacuum-deposited Ta barriers were stable against agglomeration when annealed for several hours at temperatures as high as T=380°C. However, on Ta barriers intentionally contaminated with oxygen, agglomeration of Cu films occurred within minutes when annealed above 300°C. Time-resolved reflectivity was used to study film evolution and agglomeration in situ. Atomic force microscopy was used for post-growth characterization of agglomeration. Characterization of Ta barriers by X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry demonstrated that clean Cu films on contaminated Ta barriers containing as little as 5% oxygen were unstable against agglomeration.
Etching of Platinum Thin Films by High Density Ar/Ci2/Hbr Plasma
Authors: Kim C.-I. , Kim N.-H. , Chang E.-G. , Kwon K.-H. , Yeom G.-Y. , Seo Y.-J. 
Published: April 2011

ABSTRACTPlatinum is widely researched as the electrode material for capacitor of high dielectric films in dynamic random access memory (DRAM) application. However, the dry etching of Pt is difficult because of its chemical stability. So, the dry etching of Pt remains at the preliminary work.In this work, Pt etching mechanism was investigated by using inductive coupled plasma (ICP) with Ar/Cl2/HBr gas.The peaks were found due to brominated Pt as well as chlorinated Pt in the XPS (X-ray photoelectron spectroscopy) narrow scan. Ion bombardment effects on the etched surface decreased with increasing HBr/(HBr+Cl2) gas mixing ratio. The maximum etch rate of Pt was 105 nm/min at the HBr/(HBr+Cl2) ratio of 0. And selectivity to SiO2 was good in all samples with various HBr/(HBr+Cl2) gas mixing ratios. These results are consistent with XPS and OES (optical emission spectrometry) and single Langmuir probe.
TiN Diffusion Barrier Formation by Pulsed Source Chemical Vapor Deposition method
Authors: Jeon Hyeongtag , Lee Sangsoo , Ahn Taehang , Uhm Jangwoong 
Published: April 2011

ABSTRACTTiN film is applied as a diffusion barrier and an adhesion promotion layer in the ultralarge scale integrated circuit (ULSI) devices. These TiN thin films are usually deposited by sputtering and chemical vapor deposition (CVD) methods. The CVD method is now studied intensively due to its satisfiable step coverage and compatibility with current device fabrication process. There are several different CVD methods already proposed such as LPCVD, MOCVD and PECVD. These proposed CVD methods have many disadvantages such as impurity incorporation and particle generation due to gas phase reactions between source and reactant gases. To solve these problems, we propose a new CVD method to reduce impurities and particles which is the pulsed source chemical vapor deposition (PS-CVD) method. In this method, the source, reactant and purge gases are introduced into reaction chamber, separately. TiN films are deposited using TiCl4, NH3 and Ar by alternately introducing into reaction chamber. In detail, TiCl4 source is introduced and adsorbed on Si substrate and then Ar gas purges this source gas. Continuously, NH3 gas in supplied into reaction chamber and adsorbed on the Ti-adsorbed Si substrate and then Ar gas is again introduced to purge NH3 gas. These four steps are one cycle. The main variables in this experiment are source pulse time, source purge time, reactant pulse time, reactant purge time, and so on. The deposition characteristics are also different depending on substrate temperatures. Above the thermal decomposition temperatures, the film thickness is a function of the source pulse time like conventional CVD. Below the thermal decomposition temperatures, the film thickness is saturated and exhibits a constant value in this temperature range. The TiN film thickness depends only on the number of deposition cycle. The process window were determined by experimentally in this temperature range. Process variables were established, and then TiN films were deposited. The characteristics of this TiN diffusion barrier were analyzed. The surface microroughness, the chemical composition and contaminant contents were measured by AFM, SEM and AES. A crystal structure and the phase identification were performed with using XRD and the sheet resistance was measured by a four point probe. These results will be discussed and compared with the results of TiN formed by sputtered and conventional CVD methods.
Integration of Multi-Level Copper Metallization into a High Performance Sub-0.25μM Technology
Authors: Venkatraman R. , Jain A. , Farkas J. , Mendonca J. , Hamilton G. , Capasso C. , Denning D. , Simpson C. , Rogers B. , Frisa L. , Ong T. P. , Herrick M. , Kaushik V. , Gregory R. , Apen E. , Angyal M. , Filipiak S. , Crabtree P. , Sparks T. , Anderson S. , Coronell D. , Islam R. , Smith B. , Fiordalice R. , Kawasaki H. , Klein J. , Venkatesan S. , Weitzman E. 
Published: April 2011

ABSTRACTWe report the integration of six levels of Cu interconnects using dual inlaid patterning in a 0.2 μm logic technology. A review of process technology as well as device performance shortcomings using conventional aluminum metallization has been presented. Two tantalum based barriers, TaNx and Ta-Si-N as well as a titanium based barrier, CVD TiN, have been evaluated for their applicability. The use of embedded barriers wherein the barrier is formed below the surface of the dielectric has also been discussed as a potential option. No degradation to the device front-end parametrics were found with the choice of an appropriate barrier. Planarization by Cu CMP introduces surface topography that needs to be minimized in order to process multiple levels of interconnects within specified sheet resistance distributions for a range of line widths. Excellent results with highly planarized levels of metallization have consistently been achieved through an optimization of the unit processes and device integration.
Electrochemical and Material Study of Electroless Ternary Barriers for Copper Interconnects
Authors: Lopatin S. , Kim Y. , Shacham-Diamand Y. 
Published: April 2011

ABSTRACTElectroless cobalt-rich CoWP ternary alloys with a low weight percent of tungsten (∼ 2 percent) and a high phosphorus content (∼11 weight percent) have been deposited in basic solution onto copper and cobalt in integrated Cu damascene structures. A capability of the electroless CoWP deposition to form conformal barrier/protection films was demonstrated. Conformal 10 nm thick CoWP layer was also formed on the sidewalls of 30–40 nm wide seam of aspect ratio about 5:1 on the top of 0.4 μm wide in-laid Cu line.
Metal - Gan Contact Technology
Authors: Lau S. S. 
Published: April 2011

ABSTRACTIn this talk, we summarize the experimental results obtained on metal-GaN interactions in our laboratory. These interactions include the epitaxial growth of metal thin films on chemically cleaned GaN surfaces, metal silicides for Schottky contacts and metallization schemes for ohmic contacts. We found that many fcc and hcp metals can grow epitaxially on (0001) GaN surfaces at room temperature without in-situ surface cleaning. Metal silicide contacts (such as PtSi) may be more suitable for high temperature applications than elemental contacts, due to the thermal stability of silicides. The intrinsic mechanisms for ohmic behavior for various metal contacts are not well understood at present. More consistent barrier height values measured experimentally can shed light on this issue. Due to the defective nature of the GaN layers, carrier transport across the metal/GaN interface can be due to a number of transport mechanisms, thus making accurate determination of the barrier height difficult. In spite of these difficulties, it seems possible to draw certain general conclusions on the electrical behavior of metal contacts on n-GaN.
PVD Ti-Si-N Films Process Development for Copper Interconnect Applications
Authors: Zhang Jiming , Venkatraman Ram , Wilson Terri , Fiordalice Robert , Gregory Rich , Weitzman Elizabeth 
Published: April 2011

ABSTRACTA process has been developed for the deposition of amorphous Ti-Si-N films using reactive ion sputtering of a TiSi target. The Ti-Si-N films have been extensively characterized over a wide range of process parameters. Resistivities of the films less than 300 μΩ-cm have been achieved. Stress measurements on Ti-Si-N films indicate that the film stress changes from tensile to compressive as the nitrogen composition is increased. Near-zero film stresses were achieved by choice of optimum nitrogen N2 flow. SIMS analysis of Cu diffusion through blanket PVD Ti-Si-N (300Å) after an anneal at 390°C/3 hour showed a near overlap of the Cu profile compared to the profile of an unannealed SiO2/PVD Ti-Si-N /Cu film stack, indicating that the Cu did not diffuse significantly through the barrier after anneal. Low contact resistance (0.8 Ω) and low (< 10−11 A) leakage were obtained using a dual inlaid structure with a 300 Å Ti-Si-N processed with optimized conditions. These results showed that Ti-Si-N could be used as a potential barrier for copper metallization.
Barriers For Copper Interconnections
Authors: Wong S. Simon , Ryu Changsup , Lee Haebum , Kwon Kee-Won 
Published: April 2011

ABSTRACTThe integration of Cu interconnections will require sophisticated structures to prevent Cu from coming into contact with devices. The barriers for Cu also must have good adhesion with dielectric and Cu, and yield desirable microstructure of Cu. This paper discusses several critical barrier requirements and compares the properties of Ta and Ti/TiN barrier systems.