bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanoporous Silica for Low k Dielectrics
Authors: Ramos Teresa , Roderick Kevin , Maskara Alok , Smith Douglas M. 
Published: April 2011

AbstractConsiderable progress has been made in development of thin films of nanoporous silica (also known as aerogels or low density xerogels) for ILD and IMD applications. Advantages of these materials include high thermal stability, small pore size, and similarity to conventional deposition processes, precursors and final material (silica). We have previously reported success in synthesizing low density, low dielectric constant (K<2) thin films using ambient pressure processing. However, processing of those films was complicated due to large number of process steps and difficulties in independently controlling both film thickness and film porosity.Nanoglass has now developed a new process which considerably reduces the number of process steps and allows independent control of both film thickness and porosity. The dielectric constant of the films can be tailored between 1.3 and 2.5. These films have improved mechanical properties due to controlled pore size and narrow pore size distribution and also because of higher density. The trade-offs between density, mechanical strength and dielectric constant for these types of porous solids will be elucidated. The known properties of the film and the process flow for deposition and post-deposition curing and the role of the relative rates of reaction, gelation, aging, and drying will be presented.
Controlled Incorporation of Nitrogen at The Top Surface of Silicon Oxide Gate Dielectrics
Authors: Niimi H. , Koh K. , Lucovsky G. 
Published: April 2011

AbstractDuring a high RF power (60–100 W) N20/He remote plasma oxidation of Si(100) at 300 °C, nitrogen atoms have been incorporated at the top surface of an ultra-thin (1.0–2.5 nm) oxide. Online Auger electron spectroscopy (AES) has been used to estimate the dielectric film thickness and track the evolution of the film growth. A chemically shifted Si-LW feature from the high RF power oxidation sample indicates that the nitrogen is bonded to the silicon at the top surface of the oxide film. The stability of the bonded nitrogen is also evident in the persistence of the N-KLL Auger peak following (i) a 30 s rapid thermal anneal (RTA) in Ar at 900 °C and (ii) a remotely excited He plasma treatment at 300 °C for 15 s.
Electronic Structure of Si-Si Bond in Si3n4 and Sio2: Experiment and Simulation by Mindo/3
Authors: Gritsenko V.A. , Milov A.D. , Morokov Yu.N. , Novikov Yu.N. , Wong H. , Cheng Y.C. 
Published: April 2011

AbstractThe trapping properties of the Si-Si bond in Si3N4 and SiO2 were investigated. The MINDO/3 calculations show that the spin polarization of the Si-Si bond with a captured hole takes place in both SiO2 and Si3N4. The ESR (Electron Spin Resonance) measurements were made in Si3N4 with captured electrons and holes. The number of localized carriers was of two orders of magnitude larger than that used by others. The ESR signal of localized electrons and holes was not observed. A new mechanism of the antiferromagnetic ordering of localized electrons and holes in an insulator with a large concentration of traps is proposed. According to this mechanism, the antiferromagnetic ordering in Si3N4 may be caused by the resonance tunneling of localized spins through nonoccupied traps. We believe that the deep traps responsible for the electron and hole capturing in Si3N4 are the Si-Si bonds.
Effect of Post-Oxidation on the Oxygen Deficiency of Buried Oxides
Authors: Soo Seol Kwang , Karasawa Toshifumi , Koike Hidemi , Ohki Yoshimichi , Tachimori Masaharu 
Published: April 2011

AbstractThe effect of post-oxidation of the silicon-on-insulator structure produced by implantation of oxygen (SIMOX) upon neutral oxygen vacancies (O3=Si-Si=O3, “=” denotes bonds with three separate oxygens) in the buried oxide has been investigated. It is observed that the photoluminescence intensity from the vacancies and the thickness of buried oxide increase after the post-oxidation. An Ar plasma was used to expose the buried oxide in order to convert the vacancies to E'r (O3=Si, “” denotes an unpaired electron) centers which are detectable by electron-spin-resonance. The total number of E’ r centers was found to increase, which should suggest a similar increase in the number of the vacancies in the buried oxide. Similar measurements repeatedly done on the buried oxide by changing its thickness by etching revealed that the increased part of oxide by the post-oxidation contains the vacancies with a similar density to the original part of oxide, and that the post-oxidation scarcely affects the oxygen deficiency of the original part.
Observation of the Full Interface of Multi-level Interconnects for Sub-Half-Micron Devices
Authors: Hirose Y. , Katayama T. , Fujiki N. , Ohno T. , Sekine M. , Koyama H. 
Published: April 2011

1. AbstractIn recent years, the problem of electrical resistance of vias and contact holes has become greater because a thin insulated layer formed at the interface of the hole has become a serious difficulty in the manufacture of ULSIs. In using conventional techniques of cross sectional analysis to examine the cause, only one cross section of the hole can be analyzed, therefore there is the problem that the two-dimensional interface layer formed cannot be analyzed exactly.In this paper, we have developed a new observation method to inspect two dimensions of the layer formed locally at the interface of the holes. This new observation method gives the configuration, coverage, and element map of the interface layer because the full interface of holes can be inspected; therefore, the process margin can be discussed. The present technique is demonstrated in failure analysis of sub-half-micron vias filled with tungsten.
A Quantum Mechanical Investigation of Positively Charged Defects In SiO2 Thin Film Devices
Authors: Ferreira Antonio M. , Kama Shashi P. , Brothers Charles P. , Pugh Robert D. , Singaraju Babu B. K. , Vanheusden Karel , Warren William L. , Devine Roderick A. B. 
Published: April 2011

AbstractAb initio Hartree-Fock and second-order Möller-Plesset theory calculations have been performed to investigate the stability of triply-coordinated 0+ centers in the Si-O-Si network of amorphous SiO2. The calculations reveal that the H+ ion binds with a bridging O center to form a very stable (De > 6 eV) trivalent O complex. Capture of an electron by the positively charged protonated complex, however, is predicted to immediately lead to the dissociation of the O-H bond. A relatively weaker, but stable bond is also formed between the bridging O atom and a +SiH3 ion.
Reaction Pathways for Nitrogen Incorporation at Si-SiO2 Interfaces
Authors: Koh K. , Niimi H. , Lucovsky G. 
Published: April 2011

AbstractThis paper presents experimental studies in which N-atoms have been incorporated at Si-SiO2 interfaces by forming the interface and oxide film by a 300°C remote plasma assisted nitridation/oxidation process using N2O. Process dynamics have been studied by on-line Auger electron spectroscopy (AES) by interrupted plasma processing. Plasma-activated species have been identified by in-situ mass spectrometry (MS) and optical emission spectroscopy (OES). Based on AES studies using N2O, O2 and sequenced N2O and O2 source gases, reaction pathways for N-atom incorporation i) at and/or ii) removal from buried Si-SiO2 interfaces have been identified, and contrasted with reaction pathways for nitridation using conventional furnace processing. The active species for N-atom incorporation is NO+, and for oxide growth, O2.
Processing of Silicon Oxides Thin Films by Thermal LPCVD Starting from Teos Mixtures
Authors: Vamvakas Vassilis Em. , Davazoglou Dimitris , Vahlas Constantin 
Published: April 2011

AbstractA thermodynamic simulation is presented of the low pressure chemical vapor deposition (LPCVD) of silicon oxide thin films starting from TEOS and N2O mixtures within the temperature range 700 – 1300K, by minimizing the total Gibbs energy of the C‐H‐N‐O‐Si chemical system. It was found that at temperatures up to 1173K and N2O/TEOS molar ratios up to approximately 7, SiO2 films contain carbon impurities, while above this ratio deposits are carbon free. A corresponding experimental investigation is also presented where the obtained submicronic films are slightly substoichiometric in oxygen. They contain small carbon impurities the concentration of which decreases with the N2O/TEOS molar ratio.
Tantalum Pentoxide for Advanced DRAM Applications
Authors: McKinley K. A. , Sandier N. P. 
Published: April 2011

AbstractTantalum pentoxide (Ta2O5) films were deposited from the reaction of tantalum pentaethoxide (Ta(OC2H5)5) and oxygen (O2) using the Lam Research Corporation DSM™9800 advanced LPCVD reactor. Typical films were deposited at a rate of 0.9 – 1.1 nm/min at 400°C. The films were stoichiometric with an O/Ta ratio of 2.57/1.00 and excellent compositional uniformity. Conformity was >95% indicating that the process is surface reaction rate limited. Films with non‐uniformities <2.2% were deposited on 300 mm wafers. The deposited non‐uniformity on 150mm and 200mm wafers was <2.0% ‐1σ within a wafer, wafer to wafer within a batch, and batch to batch. The dielectric constant for as‐deposited films was 22–24, and as high as 34 for films which were heat treated. Various post deposition heat treatments were performed to improve the capacitor's electrical properties. Superior results were obtained from rapid thermal annealing (RTA) in N2O compared with RTA in O2 and two‐step UV‐O3 followed by high temperature annealing in dry O2. Values for the leakage current of <10-8 A/cm2 at 1.2 volts negative bias (worst case) and breakdown >5 MV/cm at 1.6μΑ with tegox<2.5 nm have been obtained. These values meet the requirements for 256 Mbit DRAM memory devices Bottom and top electrode formation and integration issues are also addressed.
POST‐METALLIZATION ANNEALING OF ULTRA‐THIN REMOTE PLASMA ENHANCED CVD OXIDES
Authors: Ragnarsson L‐Å , Lundgren P. , Landheer D. 
Published: April 2011

AbstractA remote plasma enhanced chemical vapour deposition (RPECVD) process was used to deposit thin silicon dioxides on silicon substrates. The oxide properties were compared with thermal oxides with similar thicknesses (2.5–9 nm) using capacitance‐voltage (C‐V), current‐voltage (I‐V) and constant voltage stress measurements (I‐t). Post‐metallization annealing (PMA) showed different annealing dynamics as compared to the thermal oxides for anneal times below approximately 1000 s (at 260 °C) after which the dynamics were similar. The deposited oxides had a higher initial interface state density (Dit) than the thermal oxides, but after PMA they were found to be of the same quality as the thermal oxides. Positive charging of the deposited oxides during constant voltage stress was the same as for thermal oxides, showing that the stress endurance of the two are similar.
Electrical Properties of Batio3 thin Films Flash‐Evaporated on si and sio2/Si
Authors: Caballero J.V. , Avila R. E. , Fuenzalida V.M. , Eisele I. 
Published: April 2011

AbstractBaTiO3 (BT) thin films were prepared by flash evaporation onto p‐Si and SiO2/p‐Si. The films are amorphous and remain so after a thickness reduction by 20% by annealing at 500 °C for 3 min. in O2 atmosphere. The electrical characteristics were measured at room temperature.Electron injection at the Al to BT interface of Al/BT/Si capacitors is enhanced by the Schottky effect, yielding a value of 11.2 for the dielectric constant of BT. Modeling current‐time measurements yields a trap density of 1024 m3, 0.82 eV below the conduction band. Capacitance‐voltage curve shifts due to bias stress on AI/BT/SiO2/Si capacitors are interpreted as caused by electron injection and trapping in the BT films. Starting deposition at 170 °C or post‐deposition annealing reduces the trap density and increases the C‐V curve shifts by bias stress, from 0.3 to over 14 V at bias stress of‐10 V.
Characterization of the Thin Diamond-Like Carbon Films Deposited Using Rf Inductively Coupled Ch4- Plasma Source
Authors: Druz B. , Polyakov V.I. , Ostan E. , Hayes A. , Rukovishnikov A.I. , Rossukanyi N.M. , Khomich A.V. 
Published: April 2011

AbstractDiamond-like carbon (DLC) films with 4-400 nm thickness were deposited on silicon substrates using direct ion beam from an RF inductively coupled CH4 - plasma (ICP) source. The dependence of the film electrical and photoelectrical properties on methane flow were examined. Two kinds of trapping centers with different activation energies and capture cross-sections, and very low densities were discovered by the Q-DLTS method. The influence of thermal annealing in air at 100-450°C was investigated. The current leakage and defect concentration were reduced while electrical breakdown field and photoresponse were increased in annealed films. The results obtained have been used for optimization of the technology to prepare thin films with good protective, electrically insulating, and passivating properties.
Simulation of Structure and Dynamics of Amorphous SiO2
Authors: Kogure Y. , Doyama M. 
Published: April 2011

AbstractA molecular dynamics computer simulation of amorphous SiO2 has been made to investigate the structure and dynamics. The effects of the external stresses on the amorphous structure were investigated through the radial distribution function, the distribution of Si‐O‐Si bond angles, and the distribution of coordination numbers.
Surface Oxidation of Si (111) By High Purity Ozone and Negative Ions Produced by Rydberg Electron Transfer
Authors: Nonaka H. , Kurokawa A. , Nakamura K. , Ichimura S. 
Published: April 2011

AbstractThe sub‐initial oxidation of Si (111) surface by a high‐flux pure ozone was investigated using X‐ray photoelectron spectroscopy. In addition to the advantage of the pure ozone which can efficiently oxidize the Si surface at room temperature, the high‐flux ozone was found to further enhance the oxidation. The possibility of producing negative ions of oxidizing gases using Rydberg electron transfer was also investigated.
Chlorine Precursors For Gate Oxidation Processes
Authors: Mc Geary M.J. , Mertens P.W. , Vermeire B. , Heyns M. , Sprey H. , Lubbers A. , Schaekers M. 
Published: April 2011

Abstract1,1,1‐Trichloroethane (TCA) has played a vital rôle in contemporary semiconductor fabrication as a source for chlorine during the oxidation of silicon substrates. However, TCA has been identified as an ozone depleting compound by the Montreal Protocol, and in the United States The Clean Air Act Amendments of 1990 severely restrict its use in many applications. This paper discusses oxalyl chloride (OC) and trans‐ 1,2‐dichloroethylene (DCE) as alternatives to TCA for silicon oxidation processes. Information on precursor vapor delivery, atmospheric chemistry, industrial hygiene, and combustion chemistry will be presented along with comparisons of metal decontamination efficiency and electrical properties (Qbd) for oxides grown in the presence of each precursor The suitability of OC for low temperature, ultra‐thin oxidation processes will also be addressed.
Parallel Down Flow Rinsl : Water Saving Technology in Wafer Rinse
Authors: Hiratsuka Y. , Fujikawa N. 
Published: April 2011

AbstractWe had proposed parallel downflow rinse which was capable of draining out chemical carried over to rinsing bath together with wafer about twice as fast as overflow rinse.
In an attempt to further improve rinsing efficiency of PDR, we have investigated (1) the effect of wafer carrier shape, and (2) removal of boundary layer on wafer surface. Boat‐type wafer holder is preferable to conventional cassette. Three stirring techniques adequate for PDR, namely, megasonic irradiation. N2 bubbling, liquid level shifting, are found effective to remove chemical ion remaining boundary layer in measuring conductivity and resistivity.
Intersubband Transitions in Microcavities with a Grating: Coupled Oscillators
Authors: Duboz J.-Y. 
Published: April 2011

ABSTRACTWe theoretically study the absorption in grating coupled quantum wells in a cavity. We describe the coupling betwen the three oscillators present in the structure: The intersubband transition, the grating and cavity modes. We show that optical mode anticrossings should be observed. The splitting between the cavity mode and the intersubband transition is calculated but its experimental observation would require electronic coherence times longer than what was measured.
Emission Efficiency in InAs LEDs Controlled by Surface Recombination
Authors: Kane M J , Braithwaite G , Emeny M T , Lee D , Martin T , Wight D R 
Published: April 2011

ABSTRACTIn this paper, light emitting diodes (LEDs) are used to study the recombination dynamics of minority electrons in p type InAs. The LEDs operate through injecting electrons into p type material with a free surface. When surface recombination is dominant, the output of the LEDs is shown to depend only on the strength of the radiative recombination and not on its efficiency. When surface recombination is not dominant, the dependence of the LED efficiency on the thickness of the active layer is analysed to give the minority carrier diffusion lengths and recombination efficiencies. the electron diffusion lenSgth is shown to be 3±0.5 μm in 5×10−18 cm−3 p type InAs and 6±1 pm in 2×10 cm−3 p type material. An upper limit of∼2.1×10−28 cm6 s−1 is deduced for the total Auger recombination rate constant in p type material.
GaAs/GaInP Quantum Well Intersubband Photodetectors for Focal Plane Array Infrared Imaging
Authors: Jelen C. , Slivken S. , Brown G. J. , Razeghi M. 
Published: April 2011

ABSTRACTWe demonstrate long wavelength quantum well infrared photodetectors (QWIP) with GaAs quantum wells and GalnP barriers grown using gas-source molecular beam epitaxy. Wafers were grown with varying well widths. The optimum well width was 75 Å, which resulted in a detection peak at 13 μm and a cutoff wavelength of 15 μm Dark current measurements of the samples with 15 μm cutoff wavelength show low dark current densities. Preliminary focal plane array imaging is demonstrated.
A Novel Infrared Sige/Si Heterojunction Detector with an Ultrathin Phosphorus Barrier Grown by Atomic Layer Deposition
Authors: Banisch R. , Tilack B. , Pierschel M. , Pressel K. , Barth R. , Krüger D. , Ritter G. 
Published: April 2011

ABSTRACTIn strained Sia−xGex heterojunction internal photoemission (HIP) photodiodes the spectral response can be tailored over a wide wavelength range by varying the Ge content. In this paper heavily in situ boron doped SiGe layers with 30% Ge were grown by low pressure rapid thermal chemical vapour deposition (LP(RT)CVD). The detectors exhibit a cut-off wavelength of 8.5 μm. A delta-like P peak, incorporated by atomic layer deposition technique, shifts the cut-off to shorter wavelengths. This shift is related to an increase of the barrier height at the SiGe/Si interface caused by the narrow n+-doped layer in agreement with device simulation. In this way the trade off between critical film thickness for high Ge content film growth and absorption depth for proper detector response can be overcome.
Defect Characterization in ZnGeP2 by Time -Resolved Photoluminescence
Authors: Dietz N. , Busse W. , Gumlich H. E. , Ruderman W. , Tsveybak I. , Wood G. , Bachmann K. J. 
Published: April 2011

AbstractSteady state and time-resolved photoluminescence (PL) investigations on ZnGeP2 crystals grown from the vapor phase by high pressure physical vapor transport (HPVT) and from the melt by gradient freezing (GF) are reported. The luminescence spectra reveal a broad infrared emission with peak position at 1.2 eV that exhibits features of classical donor-acceptor recombination. The hyperbolic decay characteristic over a wide energy range, investigated from 1.2 eV up to 1.5eV, suggest that this broad emission band is related to one energetic recombination center. Higher energetic luminescence structures at 1.6eV and 1.7eV were revealed after annealing of ZnGeP2 crystals in vacuum for a longer period of time. The emission decay behavior in this energy range is characterized by two hyperbolic time constants, viewed as the supercomposition of the decay from the broad emission center peaked at 1.2eV and additional donor-acceptor recombination emissions at 1.6eV and 1.7eV, respectively. ZnGeP2 crystals grown under Ge-deficient conditions by HPVT show an additional emission structure at 1.8 eV with sharp emission fine structures at 1.778 eV related to the presence of additional donor states.
Analysis of three types of Interdiffusion Process in Ingaas/Inp Quantum-Well and their Devices Implications
Authors: Chan Michael C.Y. , Chan K. S. , Herbert Li E. 
Published: April 2011

ABSTRACTThe optical properties of In0.53Ga0.47As/InP single quantum well (QW) (with an as-grown well width of 60Å structures) interdiffused with different cation and anion interdiffusion rates have been theoretically analyzed for applications in optoelectronics. The interdiffusion of TnGaAs/InP QW structures is complicated as interdifrusion can occur for either (i) only group-Ill (In,Ga), (ii) group-V (As,P), or (iii) both group-Ill and group-V sublattices. Depending on the resulting composition profiles, the shifts (blue or red) of the transition energies can be tuned to wavelengths between 1.3μm to 1.55μm for device applications. The results show that the control of the rates of cation and anion interdiffusion offers interesting possibilities for designing optoelectronic devices such as modulators and lasers.
Optical Properties of Diffused AlGaAs/GaAs Multiple Quantum Wells and their Applications in high Power Laser
Authors: Luo Yi , Jiang Ai-Qing , Hao Zhi-Biao , Wang Jian-Hua , Lai Terry W. K. , Herbert Li E. 
Published: April 2011

ABSTRACTWe will present results for an Al0.24Ga0.76As/GaAs diffused multiple quantum well with five periods of 100/100 Å thick well/barrier layers grown in between Al0.24Ga0.76As guiding layers and cladded on top by a 1 μm thick p-Al0.44Ga0.56As layer and on the bottom by an n-Al0.44Ga0.56As layer of equal thickness, on a n+-GaAs buffer layer and n+-GaAs substrate. Vacancy enhanced QW diffusion is employed where a 2000 Å thick layer of SiO2 is deposited on top of the diffused multiple quantum well structure. Photoluminescence measurement and photovoltage measurement at room temperature show that after rapid thermal annealing for 30 sec at 1000 °C to 1040 °C, a bandgap shift of 30 nm is obtained for the exciton edge. Further, this technique is applied to a ridge waveguide laser structure to make two windows for high power output up to 36 mW. This device shows that the diffusion process may have practical applications.
Numerical Simulation of Electronic Behavior in a Finite Superlattice With a Tamm State: A Possible Submillimeter Wave Emitter Without Optical Pumping
Authors: Manzoli J. E. , Hipólito O. 
Published: April 2011

ABSTRACTWe propose a semiconductor heterostructure consisting of six coupled quantum wells of GaAs plus a larger one, all inside Al(x)Ga(l−x)As, x=0.35. Our simulation prevents that the localized electronic eigen-state at the large well, the Tamm state, will oscillate when the voltage applied across these “finite superlattice” varies fast. We include exchange and correlation effects in the local density approximation and made the self-consistent calculations to the electrons at 77K varying the voltage in a gate contact of the device. We obtain the effective potential, the sub-bands (mini-bands) and respective electronic densities which enable us to simulate the temporal evolution of an electronic wave-packet when the gate-voltage is switched fast. Such a switching turns the Tamm eigen-state in a wave-packet. By the simulation we conclude that this wave-packet oscillates a Tera-Hertz frequency that can emit electromagnetic radiation as a charge oscillator. We estimate the finite superlattice capacitance and it confirms the possibility of changing the Hamiltonian faster than the period of the oscillation.