bluuebunny/crossref_metadata_2025_split huggingface dataset:
A physically-based SPICE model for the leakage current in a-Si:H TFTs accounting for its dependencies on process, geometrical, and bias conditions
Authors: Servati Peyman , Nathan Arokia , Sazonov Andrei 
Published: April 2011

ABSTRACTWe have developed a physically-based analytical model of the static current-voltage characteristics of hydrogenated amorphous silicon (a-Si:H) inverted staggered thin film transistors (TFTs) in the reverse (leakage) regime (VG<0,VD>0). We studied analytically (based on measurement data) the dependence of the leakage current on process parameters (i.e. the deposition-temperature-dependent phosphorus diffusion profile in the a-Si:H active layer), geometrical parameters (i.e. a-Si:H thickness, source/drain overlap areas), and operating conditions (i.e. VG, VD). The derived analytical model is implemented in HSPICE. The simulated and measured results are in good agreement with a discrepancy of less than 5%.
A Study of the Time Scales of Processes Responsible for the Light-induced Degradation of a-Si:H by Pulse Illumination
Authors: Stradins Paul , Kondo Michio , Matsuda Akihisa 
Published: April 2011

ABSTRACTDegradation properties of a-Si:H and a-Si:D by pairs of intense light pulse pairs are examined. By varying the delay time between pulses in a pair while keeping the total illumination time and dose constant, the time scales involved in the light-induced defect creation are investigated. In nanosecond pulse case, we find a sharp drop in degradation efficiency with delay time, followed by further gradual decrease at much longer times. For microsecond pulses, the degradation efficiency varies with the delay time in microseconds. The recombination proceeds bimolecularly and is largely completed during the pulse. It is suggested that the first stage of degradation is related to bimolecular recombination that takes place during the pulse. The second stage is possibly related to longer-living metastable species.
A Critical Test of Defect Creation Models in Hydrogenated Amorphous Silicon Alloys
Authors: Palinginis Kimon C. , Yang Jeffrey C. , Guha S. , Cohen J. David 
Published: April 2011

ABSTRACTUsing the modulated photocurrent method we studied the deep defect creation and annealing kinetics of amorphous silicon-germanium alloys with Ge fractions below 10at.%. The modulated photocurrent spectroscopy clearly discloses the existence of two distinct bands of majority carrier traps in these alloys. The bands were identified as neutral Si dangling bonds and neutral Ge dangling bonds. Our studies show clearly that the Si and Ge defects directly compete with each other during annealing, implying a global reconfiguration mechanism. The creation kinetics reveal the usual t1/3 illumination time dependence for the total deep defect density. However, the individual densities of Si and Ge defects have different time dependencies. The details of the creation and annealing kinetics of Ge and Si defects are used to test predictions of certain defect creation models.
Mechanisms for Metastability in Hydrogenated Amorphous Silicon
Authors: Biswas R. , Li Y.-P. , Pan B.C. 
Published: April 2011

ABSTRACTWe propose metastabilities in amorphous silicon fall into two classes. One class is the local changes of structure affecting a macroscopic fraction of sites. The other class is the metastable generation of dangling bonds with mid-gap states. The local metastability is explained by a new metastable state formed when H is flipped to the backside of the Si-H bond at monohydride sites. The dipole moment of this H-flip defect is larger and increases the infrared absorption. This H-flip defect accounts for large structural changes observed on light soaking including larger absorption and volume dilation. We propose a new model for the generation of metastable dangling bonds. The new ‘silicon network rebonding model’ involves breaking of weak silicon bonds and formation of isolated dangling bonds, through rebonding of the silicon network. Hydrogen motion is not involved in metastable defect formation. Defect formation proceeds by breaking weak silicon bonds and formation of dangling bond-floating bond pairs. The floating bonds migrate through the network and annihilate, producing isolated dangling bonds. This new model provides a new platform for understanding the atomistic origins of lightinduced degradation.
Modeling the Optical Quantum Efficiency of Thin Film Amorphous Silicon Solar Cells
Authors: Rowlands Sally-anne F. , Livingstone John , Lund Christopher P. 
Published: April 2011

ABSTRACTThe optical quantum efficiency and spectral response of p-i-n thin film amorphous silicon (a-Si:H) solar cells have been modeled using software based on optical admittance analysis. The optical constants of a-Si:H and Indium Tin Oxide (ITO) thin film layers have been measured by Variable Angle Spectroscopic Ellipsometry (VASE) and used as inputs into the optical admittance analysis program in order to model cells constructed from these films.Amorphous silicon thin films and p-i-n assemblies have been deposited by glow discharge and reactive sputtering techniques. The optical constants of doped and intrinsic a-Si:H thin films were determined by VASE and the film thickness verified by Scanning Electron Microscopy studies. The optical constants of commercially available transparent conducting oxide (TCO) coated substrates have also been determined by VASE.The experimental transmission spectra of p-i-n assemblies are compared with transmission spectra that have been modeled using the measured optical constants. Results of modeling different a-Si:H solar cell structures using these materials are presented, including a study of the optimal TCO layer thickness for p-i-n a-Si:H solar cells. This work shows that optical admittance modeling gives a good prediction of the optical behavior of p-i-n assemblies, but that accurate measurements of the optical constants of the component films are required in order to model effectively the optical quantum efficiency and photocurrent.
Relation between Growth Precursors and Film Properties for Plasma Deposition of a-Si:H at Rates up to 100 Å/s
Authors: Kessels W.M.M. , Smets A.H.M. , Hoefnagels J.P.M. , Boogaarts M.G.H. , Schram D.C. , Sanden M.C.M. van de 
Published: April 2011

ABSTRACTFrom investigations on the SiH3 and SiH radical density and the surface reaction probability in a remote Ar-H2-SiH4 plasma, it is unambiguously demonstrated that the a-Si:H film quality improves significantly with increasing contribution of SiH3 and decreasing contribution of very reactive (poly)silane radicals. Device quality a-Si:H is obtained at deposition rates up to 100 Å/s for conditions where film growth is governed by SiH3 (contribution ∼90%) and where SiH has only a minor contribution (∼2%). Furthermore, for SiH3 dominated film growth the effect of the deposition rate on the a-Si:H film properties with respect to the substrate temperature is discussed.
Ion-Assisted Deposition of Silicon Epitaxial Films with High Deposition Rate Using Low Energy Silicon Ions
Authors: Oberbeck Lars , Wagner Thomas A. , Bergmann Ralf B. 
Published: April 2011

ABSTRACTIon-assisted deposition (IAD) enables low temperature (≥ 435°C), high-rate (≤ 0.5 μm/min) epitaxial growth of silicon films. Therefore, IAD is an interesting deposition technique for microelectronic devices and thin film solar cells. The Hall-mobility of monocrystalline epitaxial layers increases with deposition temperature Tdep and reaches values comparable to those of bulk Si at Tdep ≥ 540°C. Polycrystalline epitaxial layers exhibit inhomogeneous electrical properties, as shown by Light Beam Induced Current measurements. Recombination within the grains dominates over recombination at grain boundaries. Secco etching identifies an inhomogeneous density of extended structural defects in the polycrystalline epitaxial layers and in the substrate. A major part of the extended defects in the epitaxial layers originates from defects in the substrate.
Low temperature selective Si epitaxy by reduced pressure chemical vapor deposition introducing periodic deposition and etching cycles with SiH4, H2 and HCl
Authors: Kim Hong-Seung , Shim Kyu-Hwan , Lee Jeong-Yong , Kang Jin-Yeong 
Published: April 2011

ABSTRACTThis paper presents the experimental results of selective Si epitaxial growth from 650 °C to 700 °C on (100) silicon wafers with oxide patterns using reduced pressure chemical vapor deposition with the SiH4-HCl-H2 gas system. In addition, an HCl etching process is introduced and the conditions of the deposition and etching processes are addressed to sustain the selectivity. As a result, we noted that the addition of HCl serves not only to reduce the growth rate on bare Si, but also to suppress the nucleation on SiO2. In these experiments it has been also observed that the Si layer was grown to 3 nm while sustaining the selectivity. Moreover, further introduction of the HCl etching process following the deposition allowed a 50 nm-thick film to sustain the selectivity for twenty periods.
Crystalline Si Films Grown Epitaxially at Low Temperatures by ECR-PECVD
Authors: Platen J. , Selle B. , Christiansen S. , Nerding M. , Schmidbauer M. , Fuhs W. 
Published: April 2011

ABSTRACTElectron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) is used to grow thin epitaxial films on Si(100) wafers. We report on systematic variations of deposition parameters like substrate temperature, substrate dc bias voltage, and gas composition. The structural quality was significantly improved by increasing the substrate temperature from 325 to 500 °C. Simultaneously, compressive lattice strain tends to increase. A negative dc bias voltage resulted in highly disordered films and increased surface roughness due to enhanced ion damage. In contrast positive bias voltages decreased the defect creation by reducing the ion bombardment of the surface during growth. Under so far optimized conditions the remaining disorder is given by two-dimensional, extended defects running parallel to the growth direction and forming grain boundaries with a lateral spacing of 500–700 nm. The single grains are essentially free of one- and two-dimensional defects and show the same orientation as the substrate. By reducing the H2 dilution and adding Ar to the excitation gas the deposition rate increased from 5.3 to 16.2 nm/min. This resulted in inferior structural quality which might be attributed to the reduced etching effect, the enhanced ion bombardment and/or the increased growth rate.
Room Temperature Recrystallization of Electroplated Copper Thin Films: Methods and Mechanisms
Authors: Walther D. , Gross M. E. , Evans-Lutterodt K. , Brown W. L. , Oh M. , Merchant S. , Naresh P. 
Published: April 2011

AbstractWe report a comparison of the room temperature recrystallization of electroplated (EP) copper in blanket films as a function of thickness measured by focused ion beam (FIB) microscope images and sheet resistance measurements. Both sets of data show an increase in rate with film thickness from 0.75νm up to 5νm, while little recrystallization is observed in films thinner than 0.75νm. Interestingly, the recrystallization rates from FIB analysis are consistently faster than those from the sheet resistance measurements. These data suggest that the recrystallization is initiated close to the top surface of the EP Cu film, but that in thinner films a high surface-to-volume ratio allows surface inhibition or pinning to retard the transformation. A Johnson-Mehl-AvramiKolmogorov (JMAK) analysis of the two data sets yields unusually high values for the Avrami exponent μ of up to 7 for the FIB data, while lower values of around 4 are obtained for the sheet resistance data. X-ray diffraction pole figures of the films have also been collected and correlations between the crystallographic texture, film thickness and recrystallization are discussed.
Electromigration Characterization Versus Texture Analysis in Damascene Copper Interconnects
Authors: Berger T. , Arnaud L. , Gonella R. , Touet I. , Lormand G. 
Published: April 2011

AbstractWe have studied the effect of texture (X-ray diffraction pole figures) and grain morphology (Focus Ion Beam cross-sections) on the electromigration performances of copper damascene interconnects. Three different metallizations have been characterized : Chemical Vapor Deposition copper deposited on TiN (process A) and electroplated copper deposited either on Ta (process B) or TaN (process C). The reliability performance of these interconnects has been evaluated using both Wafer Level Reliability (WLR) and Package Level Reliability (PLR) tests on 4 and 0.6 νm wide lines using single metal level test structures. On the basis of the activation energy values and failure analysis observations, we concluded that interfacial diffusion plays a key role in the electromigration phenomenon for processes B and C whereas grain boundaries seem to be the active diffusion path for process A. The existence of several failure mechanisms during electromigration tests (interfacial or grain boundary diffusions), the impact of the damascene architecture on microstructure (sidewall textures and non columnar grain shapes) and the copper propensity for twinning seem to mask the impact of texture on the electromigration reliability of copper damascene interconnects.
Novel Low-k Dual-phase Materials Prepared by PECVD
Authors: Grill Alfred , Patel Vishnubhai 
Published: April 2011

AbstractDielectric materials based on Si, C., O, H (SiCOH) have been demonstrated previously with dielectric constants of about 2.8. This value could be potentially further reduced by increasing/introducing porosity in the SiCOH films. Depositing multiphase films containing at least one thermally unstable phase and annealing the films to remove this labile phase from the material could create the enhanced porosity. Dual-phase materials, SiCOH-CH, have been prepared in the present study by PECVD from mixtures of a SiCOH precursor with a hydrocarbon. The films have been characterized as-deposited and after thermal anneals of up to 4 hours at 400°C. The atomic composition of the films has been determined by RBS and FRES analysis and their optical properties have been determined by FTIR and n&k measurements. Metal-insulator-silicon structures have been used to measure the electrical properties of the dual-phase films. After an initial anneal at 400°C, accompanied by a significant loss of CH and some SiH species and a thickness loss of up to 50%, the films stabilized. Depending on the deposition conditions and concentration of the CH precursor in the feed gas, the dielectric constant decreased by 10-15% during the stabilization anneal and reached values as low as 2.4. These initial results indicate the possibility to further reduce the dielectric constant of PECVD produced SiCOH films and the potential to incorporate such films in the interconnect structures of future ULSI chips.
High-Temperature Mechanical Behavior and Phase Morphology of Poly(Tetrafluoroethylene)/Siloxane Nanocomposites Used as Ultra Low-k Dielectrics
Authors: Xu Ping , Qu Shichun , Rosenmayer Tom , Lin Min Y. 
Published: April 2011

AbstractPoly(tetrafluoroethylene) (PTFE)/siloxane nanocomposites have been prepared as ultra low-k dielectrics. These new nanocomposites show excellent high-temperature mechanical properties compared to unfilled PTFE while their dielectric constant almost remains unchanged. Specifically, the data from the dynamic mechanical study indicates that these nanocomposites have the mechanical behavior similar to that of crosslinked polymers. Small-angle neutron scattering (SANS) has been carried out to characterize the phase morphology of the PTFE/siloxane nanocomposites and the size of the inorganic networks. It has been shown that no phase separations or orientations appear in these nanocomposites in the range of 12 to 469 nm. These SANS results suggest that these materials are single-phase nanocomposites that are very homogeneous and isotropic. They are basically PTFE-based molecular composites.
A Study on CVD TaN as a Diffusion Barrier for Cu Interconnects
Authors: Im Se-Joon , Kim Soo-Hyun , Park Ki-Chul , Cho Sung-Lae , Kim Ki-Bum 
Published: April 2011

AbstractTantalum nitride (TaN) films were deposited using pentakis-diethylamido-tantalum [PDEAT, Ta(N(C2H5)2)5] as a precursor. During film growth, N- and Ar-ion beams with an energy of 120 eV were supplied in order to improve the film quality. In case of thermallydecomposed films, the deposition rate is controlled by the surface reaction up to about 350 °C with an activation energy of about 1.07 eV. The activation energy of the surface reaction controlled regime is decreased to 0.26 eV when the Ar-beam is applied. However, in case of Nbeam bombarded films, the deposition is controlled by the precursor diffusion in gas phase at the whole temperature range. By using Ar-beam, the resistivity of the film is drastically reduced from approximately 10000 µω-cm to 600 µω-cm and the density of the film is increased from 5.85 g/cm3 to 8.26 g/cm3, as compared with thermally-decomposed film. The use of N-beam also considerably lowers the resistivity of films (∼ 800 µω-cm) and increases the density of the films (7.5 g/cm3). Finally, the diffusion barrier properties of 50-nm-thick TaN films for Cu were investigated aftre annealing by X-ray diffraction analysis. The films deposited using N- and Arbeam showed the Cu3Si formation after annealing at 650 °C for 1 hour, while thermallydecomposed films showed Cu3Si peaks firstly after annealing at 600 °C. It is considered that the improvements of the diffusion barrier performance of the films deposited using N- and Ar-ion beam are the consequence of the film densification resulting from the ion bombardment during film growth.
The 2,2,6,6-Tetramethyl-2-Sila-3,5-Heptanedione Route to the Chemical Vapor Deposition of Copper for Gigascale Interconnect Applications
Authors: Claessen Rolf U. , Welch John T. , Toscano Paul J. , Banger Kulbinder K. , Kornilov Andrei M. , Eisenbraun Eric T. , Kaloyeros Alain E. 
Published: April 2011

AbstractA new class of copper(II) precursors containing silylated β-diketonate ligands has been developed for the chemical vapor deposition (CVD) growth of copper for applications in ultralarge scale integration interconnect schemes, including conformal seed layer for gigascale Cu integration and ultrathin Cu lines with enhanced conductivity characteristics. Cu(tmshd)2 (tmshdH = 2,2,6,6-tetramethyl-2-sila-3,5-heptanedione) has been studied as a representative compound and is appreciably more volatile than nonsilylated compounds such as Cu(tmhd)2 or Cu(tmod)2 (tmhdH = 2,2,6,6-tetramethyl-3,5-heptanedione; tmodH = 2,2,7-trimethyl- 3,5- octanedione). The CVD process employs Cu(tmshd)2 as the metalorganic precursor and hydrogen as the reducing and carrier gas. These films were deposited using a custom made, cold wall, stainless steel CVD. Copper films were produced at a substrate temperature of 250 – 320 °C, hydrogen flow rates of 20 - 100 sccm, deposition pressure of 0.2 - 1 Torr, and a source temperature of 120 – 135 °C. The films were analyzed by X-ray photoelectron spectroscopy, cross section scanning electron microscopy, transmission electron microscopy, four-point resistivity probe, Rutherford backscattering spectrometry and Auger electron spectroscopy.
Trench and Via Filling with Electroplated Copper: Effect of Current Density and Pulse Waveform
Authors: Seah C. H. , Mridha S. , Siew Y. K. , Sarkar G. , Chan L. H. 
Published: April 2011

AbstractA study was carried out to investigate the effect of current density and pulse waveform on the filling of line trenches and contact vias with aspect ratio of 2:1 for sub-0.25 µm device manufacturing using normal pulse plating of copper. The growth pattern of the copper films deposited using 0.05 and 0.10 A/cm2 current density gave no significant difference. Small grains were seen to have nucleated uniformly across the line trenches and via holes after 1 second of electroplating. With increasing the deposition time to 2 seconds, a slight buildup of the film thickness was observed in both trenches and vias without significant increase in the size of the copper grains. Grain growth involving the coalescence of small grains occurred after 5 seconds of plating and a further buildup in thickness and fill up of the trenches and vias occurred after 10 seconds of deposition.When the patterned wafers were plated with a pulse waveform of 3 ms on and 0.5 ms off, the filling of trenches could not be complete after 30 seconds of electroplating. A complete filling of the trenches was achieved within 30 seconds of deposition using a pulse waveform of 6 to 8 ms on and 1 to 2 ms off. When the on-period was increased above this range to 9.9 ms, voids were observed at the centre of the via holes.
Kinetic Roughening During Rare-Gas Homoepitaxy
Authors: Nabighian E. , Bartelt M. C. , Zhu X.D. 
Published: April 2011

AbstractUsing an optical reflectivity difference technique, we monitored the growth of multilayer Xe films on a commensurate monolayer of Xe on Ni(111), from 35 to 60K. A transition occurs near 40K, from rough growth at low temperature to quasi-layer-by-layer growth characterized by persistent oscillations in the reflectivity difference. We discuss this transition in terms of changes in the island formation process and the onset of second layer nucleation. The Xe sticking coefficient at 40K is obtained from the period of the oscillations in the reflectivity difference. We find that the sticking coefficient decreases with increasing fihn thickness at fixed Xe pressure.
Diamond Synthesis on Glassy Substrate With Completely Closed Reaction Chamber
Authors: Hayashi Rie , Onishi Fumitomo , Uede Mayu , Takagi Yoshiki 
Published: April 2011

AbstractFor diamond synthesis with gaseous reaction, crystalline materials such as Si and Mo were used as substrates. In this study, we used materials of noncrystalline oxide for substrates, for example, quartz glass.We used unique apparatus for diamond synthesis, completely closed system, no reaction gas was introduced to the chamber and no reactant gas was evacuated from it.Deposits were Identified as diamond with SEM, AFM and Raman spectra. With these results, we successfully confirmed our samples as diamond particles on quartz glass substrate.
Raman Studies Of LiMn2O4 Films Grown by Laser Ablation
Authors: Camacho-Lopez M.A. , Escobar-Alarcon L. , Haro-Poniatowski E. , Julieni C. 
Published: April 2011

AbstractPolycrystalline thin films of lithium manganese oxide have been grown using the pulsed-laser deposition (PLD) technique. Films of LiMnO2O4, were deposited onto Si substrates heated at temperature lower than 300°C from a sintered composite target (LiMn2O4+Li2O) irradiated with a Nd:YAG laser. The structural characterizations of these films have been carried out by Raman scattering spectroscopy which probe the local environment of cations in the LiMn2O4 framework. Raman spectra of PLD LiMn2O4 films have been investigated as a function of various growth conditions, i.e. substrate temperature, partial oxygen pressure in the deposition chamber, and target composition.