bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper Film Deposition Using H and O Atoms
Authors: Ann Halstead Judith , Locke Peter S. , Reeves Robert R. 
Published: March 2011

ABSTRACTThe formation of thin copper films by H-atom reaction with Cu(FOD)2 and Cu(HFA)2 has been demonstrated at near room temperature. Oxygen atoms have now also been reacted with these β-diketonate copper complexes, producing films of copper oxide which can be readily reduced by subsequent treatment with H-atoms. The thin copper films produced are conductive and highly adherent. The oxygen atom reaction with the copper complex produces a visible chemiluminescent glow, yielding information on the nature of the reaction process.
In-situ emissivity and temperature measurement during rapid thermal processing (RTP)
Authors: Vandenabeele P. , Schreutelkamp R. J. , Maex K. , Vermeiren C. , Coppye W. 
Published: March 2011

ABSTRACTA prototype RTP system has been developed which allows for in-situ emissivity and temperature measurements. The wafer emissivity is measured by using an optical detector at a wavelength of 2.4 μm and by modulation of the lamp power. This method permits accurate temperature determination in the range from 400 to 1200°C, independent of wafer backside roughness, backside layers, and transmit tance. The feasibility of the temperature measurement technique is demonstrated by using wafers with built-in thermocouples and highly As-doped wafers with different backside roughnesses or layers. The emissivity variations during processing can also be used to study thin film reactions in-situ. This is demonstrated for Co silicidation using probing wavelengths varying from 0.6 to 3.2 μm.
Reactions of Titanium Films with thin Silicon Dioxide, Nitride, and Oxynitride Films During Rapid Thermal Annealing
Authors: Ko Sen-Hou , Devashrajee N. M. , Murarka Shyam P. , Ding Pei-Jun , Lanford William A. 
Published: March 2011

ABSTRACTThe interactions of Ti with SiO2, Si3N4, and SiOiNy have been studied during rapid thermal annealing at 400 to 900 °C in Ar with 3% H2 ambient. X-ray diffraction, sheet resistance measurements, RBS, nuclear reaction technique to profile hydrogen, and microscopy have been employed in this study. The results of this investigation indicate that Si3N4 and SiOxNy are more stable with Ti than SiO2.
The Effect of Copper on the Titanium-Silicon Dioxide Rbaction and the Implications for Self-Encapsulatin G. Self-Adhering Metallization Lines
Authors: Russell Stephen W. , Li Jian , Strane Jay W. , Mayer James W. 
Published: March 2011

ABSTRACTCo-evaporated Cu-Ti films on thermally-oxidized Si substrates were annealed in vacuum at temperatures between 300 and 700°C. Reactions within the films and between film and substrate were monitored by Rutherford backscattering spectrometry, X-ray diffraction, transmission electron microscopy and sheet resistance. We found that, despite the competition from intermetallic compound formation, the Cu-Ti films react with SiO2 beginning at 400°C, with Ti migrating to the SiO2 interface to form both a suicide, Ti5Si3, and an oxide and to the free surface to form additional oxide. The reaction leaves relatively pristine Cu. Above 600°C, however, Cu begins to react with the underlying suicide. By comparison, pure Ti reacts with SiO2 only above ∼700°C.
TiN Metallization Barriers: From 1.2μ to 0.35μ Technology
Authors: Pintchovski Fabio , Travis Ed 
Published: March 2011

ABSTRACTThe evolution of modern integrated circuit technology to sub micron dimensions has brought about a number of challenges, specially in the field of metallization. Decreasing junction depths have imposed stringent demands on the materials used for the electrical contacts. This is due to the potential interactions between the contact metal and silicon (or suicide in the case of salicide processes) causing junction leakage and/or shorting. The solution most commonly applied to this problem is that in which a barrier material is interposed between the metallization and the contact. The material most often selected for this purpose has been TiN. TiN can be deposited via the reactive sputtering of Ti in a N2 atmosphere or it can be also obtained by sputtering Ti and then reacting it with either N2 or NH3. Shrinking VLSI dimensions have brought about the need for improved planarization for the purposes of metal definition. It has also prevented the tapering of contacts for space saving reasons. Both of these issues resulted in deep, straight wall contacts with aspect ratios greater than 1 that cannot be metallized appropriately with conventional sputtering techniques. These requirements have driven the development of a conformai CVD TiN barrier process. This paper describes the evolution of the TiN metallization barrier from the requirements of 1.2μ to 0.35μ technologies.
Reaction Growth and Morphology of An Aluminide Compound in Al-Cu/Ti-W Bilayers
Authors: Park M. , Krause S. J. , Wilson S. R. 
Published: March 2011

ABSTRACTThe effect of copper content on the reaction growth and morphology of Al12W in Al-Cu/Ti-W bilayers was studied with plan view and cross-section transmission electron microscopy. After heat treatment at 450°C for 30 minutes, a spiked growth of A112W penetrated into the grain boundaries of Al-0.5 wt.% Cu film by the reaction of Al with the Ti-W sublayer. Increasing copper addition from 0.5 to 1.5% inhibited the spiked growth of AI12W, resulting in a flat and planar layer (-150Å) of Al12W. It is suggested that increasing copper segregation in the aluminum grain boundaries during heat treatment at 450°C causes a significant change in the growth morphology of the Al12W compound.
Characterization of TiN Diffusion Barrier for Submicron Technology
Authors: Dixit G. A. , Chen F. S. , Zhang H. , Yao G. D. , Wei C. C. , Liou F. T. 
Published: March 2011

AbstractThe electrical properties and structure of reactively sputtered titanium nitride barrier metal films have been characterized. Junction leakages and yields for different post deposition treatments of the barrier metal layer are reported. TEM, x-ray diffraction and Auger electron spectroscopy have been used for the physical characterization of the TiN films.
A Mass Spectrometric Study of Process Steps of a Tungsten LPCVD Process
Authors: Silvestri T. A. , Guzzo G. C. , Brestovansky D. F. , Markle R. J. , Barber R. 
Published: March 2011

ABSTRACTThe study of the wafer atmosphere during processing has become a key practice in understanding interactions of the process gases with the wafer, internal chamber surfaces and other process gases. For today's ULSI fabrication, Low Pressure Chemical Vapor Deposition (LPCVD) of tungsten has become common for sub-micron contact and via filling and was the chosen process for this investigation. The wafer atmosphere during key process steps of the tungsten LPCVD process has been characterized by mass spectrometry. During the tungsten LPCVD process studied, the TiN surface was first conditioned for tungsten deposition by generating active nucleation sites. This is followed by the actual deposition. After the deposition, wafer backside etch with NF3 plasma, wafer removal and an in situ chamber clean with NF3 and H2 plasmas performed. This paper discusses the mass spectral analysis of the tungsten LPCVD process during the nucleation, backside etch and in situ chamber clean process steps. Additionally, this paper describes benefits of in situ gas analysis.
Pt Reactions with Ge, SiGe, and Si/SiGe Superlattices
Authors: Wang P. J. , Chang Chin-An , Meyerson B. S. , Chu J. O. , Tejwani M. J. 
Published: March 2011

ABSTRACTReactions between Pt and SiGe alloy have been studied by comparing several structures: Pt/Ge, Pt/SiGe, and Pt/Si-SiGe superlattices. The Ge, SiGe layers and Si-SiGe superlattices were grown on (100) Si substrates by the ultrahigh vacuum/chemical vapor deposition technique. Pt-Ge reactions start around 200 °C, forming PtzGe. This is followed by the formation of PtGe around 300 °C. The Pt-Ge reactions are thus similar to those of Pt-Si. The reactions between Pt and SiGe, however, involve a preferential Pt-Si reaction. At 200 °C, for example, while Pt2Ge is normally seen from the Pt/Ge system, only PtzSi is detected from both x-ray diffraction and Rutherford backscattering measurements. At higher temperatures, both the PtGe and PtSi phases form. This preferential Pt-Si reaction is observed in both Pt/SiGe and Pt/Si-SiGe superlattice structures.
Metallization Systems for Bonding of InP Laser Diodes to CVD-Diamond Submounts
Authors: Katz A. , Wang K-W. , Baiocchi F. A. , Dautremont-Smith W. C. , Lane E. , Lee C -H. , Wong Y- M. , Tai K. L. , Bacon D. D. , Luftman H. S. , Varma R. R. 
Published: March 2011

ABSTRACTSome metallization systems consisting of barrier metals and Au-Sn (multiple alternating layers) were studied as a bonding schemes of InP-based laser diodes to the first time used, CVD-diamond submounts. The first system to be studied, which was traditionally used in various other applications was Ti(100nm)/Pt(200nm)/Au(500nm)/Au-Sn(2.5 μm). This structure provided a molten Au-Sn layer of eutectic composition (80:20 wt%) on top of the Ti/Pt metals for about 6 sec, while heated at temperatures of 300 to 350°C, and allowed for efficient bonding of the device to the submount. Longer heating durations, however, led to reaction between Pt and Sn to consume significant amounts of Sn from the solder, thus elevating its melting temperature and resolidifying the solder. With optimum bonding conditions, a high quality bond of the InP-based laser diode to the CVD-diamond submount was observed, and a superior electrical performance of the diode was measured compared to diodes that were bonded with the standard In/BeO configurations. In order to maintain the superior performance of the InP laser diode bonded assembly but improve the thermodynamic stability of the metallurgical system and thus extending the bonding processing window, various metals such as W and Cr were studied as a replacement for the Ti/Pt barrier metals in between the CVD-diamond submount and the Au-Sn solder. While applying the W layer, a thin Ti(10nm) layer was introduced in between it and the Au-Sn to improve the solder wettability. The W layer was found to remain intact after heating at 350°C for durations as long as 5 min, and thus, due to the inert nature of the Au-Sn/W interface, the Au-Sn ratio was kept uniform at the eutectic liquid composition through a long heating duration (up to 5 min). Minimum reaction was observed, as well, at the Au-Sn/Cr interface, while executing a Ti(100nm)/Cr(200nm)/Au-Sn(1.5 μm) system, and thus allowed for an excellent bonding of the InP laser diodes to the CVD-diamond submounts.
High Temperature Performance, Reliability and Simulation of GaAs Mesfets with CVD Diamond Heat Sinks
Authors: Zhu L. , Tang Pin F. , Christou A. 
Published: March 2011

ABSTRACTAn investigation of the temperature stability and high temperature characteristics of GaAs FETs on CVD diamond heat sinks was carried out by modeling the high temperature electrical characteristics for GaAs MESFETs and by experimentally measuring the elevated temperature performance. The thermal characteristics were determined experimentally using infrared microscopy techniques. The thermal measurements by infrared microscopy were correlated with results of a finite element analysis calculation of the GaAs FET thermal distribution. Reliability testing at 230°C resulted in an MTF of approximately 2000 hours.
The Kinetic Effects of Layering Sequence of Al-Ge-Ni Ohmic Contact Components on (001) GaAs
Authors: Lampert W. V. , Haas T. W. , Holloway Paul H. 
Published: March 2011

ABSTRACTElectrical characterization has demonstrated dramatic differences in the amount of heat treatment time required to convert the ohmic contact metallizations from Schottky to ohmic behavior, depending on the layering sequence of the Al, Ge, and Ni metals. Additional time differences were found to be dependent on the doping concentration of the contact layer of the GaAs and on the heat treatment temperature. For samples with Ge at the metal-semiconductor interface, the time required to convert from Schottky to ohmic behavior varies inversely with the doping concentration of the contact layer and directly with heat treatment temperature. Samples with Ni at the metal-semiconductor interface converted from Schottky to ohmic behavior much faster and had a much smaller dependence on the doping concentration and the heat treatment temperature. Models to explain these observations in terms of interdiffusion of the components and phases formed will be proposed.
The Epitaxial Growth of Al on Hydrogen Terminated Si(100) Substrates with and Without Ion Bombardment
Authors: McEachernt R. L. , Laszig Dirk , Brownt W. L. 
Published: March 2011

ABSTRACTWe have demonstrated that aluminum can be grown epitaxially on H-terminated Si(100) substrates under modest vacuum conditions using thermal deposition. The effect of 1 keV to 4 keV ion bombardment during deposition was found to be either minimal or detrimental. Preliminary results from sputter-deposited Al films show very different behavior, with the films tending to relax from the epitaxial (110) texture to a (111) texture.
A Novel Wavelength Tunable Silicon Detector for Infrared Detection
Authors: Perera A. G. U. , Sherriff R. E. , Francombe M. H. , Devaty R. P. 
Published: March 2011

ABSTRACTA cryogenic extrinsic silicon detector which can detect IR photons of very low energy, i.e., down to about 5.5 meV ( 220 μm) is presented. The mechanism involves photoexcitation of carriers over low energy interfacial work function barriers at p-i or n-i interfaces in a process analogous to the classic photoelectric effect. Estimates for the responsivity and the detectivity for unoptimized commercial samples containing both p-i and n-i interfaces and a sample containing only a single p-i interface are provided by comparison with a silicon composite bolometer. The range of long wavelength thresholds (λt) observed suggests that this approach can be used to tailor detectors for different IR wavelength regions by changing the dopant impurity and the impurity concentration at levels near the metal-insulator transition. Single interface results confirm the possibility of detector optimization using multilayered structures. This should lead to a unique family of uniform monolithic IR focal plane structures with tailorable and tunable response characteristics within virtually all the IR spectral range of interest.
Photoinduced Electron Transfer Counter to the Bias Field in Coupled Quantum Wells
Authors: Stockman Mark I. , Muratov Leonid S. , Pandey Lakshmi N. , George Thomas F. 
Published: March 2011

ABSTRACTOptical excitation of electrons in an asymmetric double quantum well is theoretically examined. The well is biased to align the excited levels and permit resonant electron tunneling. Emphasis is made on the photoinduced transfer of electrons counter to the bias electric field force. A density-matrix approach is developed to describe optical excitations in the presence of an arbitrary dephasing. The excitation profiles obtained for cases of different dephasing reveal the full range of tunneling coupling between the wells from completely coherent to incoherent (stepwise).
Carrier Injection and Space Charge Effects in a-Si:H / Crystaiine Si Heterojunctions
Authors: Sanders A. , Swiatkowski C. , Grunow P. , Hirsch W. , Neitzert H. C. , Kunst M. 
Published: March 2011

ABSTRACTA study of excess carrier kinetics in a-Si:H / crystalline n-Si heterojunctions by transient photoconductivity measurements as a function of the excitation density is presented. It is observed that excess carriers can be injected from the a-Si:H in the c-Si part of the junctions, where the time associated to this injection process can be clearly resolved. The number of injected carriers increases with the number of excess carriers induced in the a-Si:H at low excitation density reaching a limit in the moderate excitation range. The driving force of the injection process is tentatively ascribed to the space charge field at the interface. The injection efficiency is estimated to be about 10%.
Influence of the photoinduced EL2 Grating on Electron and Hole Gratings Generated in GaAs
Authors: Disdier Laurent , Roosen Gerald 
Published: March 2011

ABSTRACTDynamic gratings of free carriers are generated from optical excitation of the deep EL2 level in semi insulating gallium arsenide with nanosecond pulses. The nonlinear modification of the crystal index of refraction is evidenced by degenerate four wave mixing experiments. In regards to the sample parameters, a fair agreement is obtained between the experimental values and the theoretical predictions derived from the Drude-Lorentz model and the anharmonic motion of carriers.
Two-Wave Mixing Gain vs Intensity Dependence in Photorefractive GaAs:EL2 in Presence of Strong Electron/Hole Competition
Authors: Gravey Philippe , Wolffer Nicole , Picoli Gilbert , Renais Olivier , Viallet Jean-Emmanuel 
Published: March 2011

ABSTRACTWe studied the pump intensity dependence of the 2WM gain in a photorefractive GaAs:EL2 crystal, with a 3.3 kV/cm d.c. field, at two different wavelengths. The grating period was 37 Am and the beam ratio was 4. At 1.32 μm, the characteristics exhibits a resonant behaviour (with a maximum of 0.23 cm-1). As for InP:Fe, these results can be explained by considering that thermally and optically generated carriers are of different types. The curve at 1.047 Am exhibits an original feature. At low intensities the gain as the same sign than at 1.32 μm (with a maximum of 0.12 cm-1), but the sign changes with increasing intensity and the gain tends towards an asymptotic value of -0.15 cm-1. Such behaviour may also be explained with the same model.
Non-Contact, No Wafer Preparation Deep Level Transient Spectroscopy (DlTS) Based on Surface Photovoltage (SPV)
Authors: Lagowski Jacek , Edelman Piotr , Dexter Mark 
Published: March 2011

ABSTRACTThis work reports on the theoretical modeling and experimental investigation of isothermal SPV-DLTS based on the rate window concept. Experimental implementation of the technique is done using computer analysis of the SPV transients after ceasing the illumination. The transient involves two processes – a recombination of excess minority carriers and a thermal emission of carriers trapped by surface states and bulk defects. The later process is the key one for deep level defect determination.The upper limit for the measurable deep level emission rate is provided by the recombination lifetime. This limit often exceeds, by orders of magnitude, the standard 103 s−1 limit in capacitance DLTS. The sensitivity of SPV-DLTS is of the same order as that of optical capacitance DLTS.
A New Method for Identification of Electron and Hole Traps in SI-GaAs by Modulated PITS and TSC
Authors: Zhangao Wang , Chengji Li , Hui Zhang , Yunyan Li , Lanying Lin 
Published: March 2011

ABSTRACTThe electron and hole traps in semi-insulating (SI) GaAs can not be identified by common Photoinduced Current Transient Spectroscopy (PITS) and Thermally Stimulated Current (TSC) measurements because of appearing of same sign signal for electrons and holes in both experiments. Therefore, we have developed two approaches which could be used to identify the type of the traps, and the origin of the puzzling negative peaks in the PITS spectra.The TSC and qusi-stationary Hall effect measurements have been simultaneously performed at the temperatures between 77K and 300K. The sign of Hall voltage corresponding to TSC peak shows the type of the trap.PITS spectra with applying different bias polarity to the sample were carefully measured with below gap and above gap photoexcitation. According to the change of PITS peak's height with different bias polarity, the electron and hole traps could be readily distinguished, since a negative bias makes hole no contribution to the PITS signal whereas electron swept into the sample would fill the electron traps, and consequently results in the appearence of the electron trap peaks. On the contrary, a positive bias would cause the filling of the hole traps.The negative PITS peaks appearing or vanishing can be understood if one takes into account the trap initial filling conditions, the carrier recapture and the high dark current etc.
Raman and Ellipsometric Studies of Delta-Doped GaAs
Authors: Yao H. , Schubert E. F. , Kopf R. F. 
Published: March 2011

ABSTRACTGaAs (100) samples with multiple δ-doped layers (N2D=∼2×1013/cm2) were studied by Raman scattering (RS) and spectroscopic ellipsometry (SE). A quasithree- dimensional (3D) plasmon-phonon coupled mode (L+), probed at λ= 514.5 nm, from a 9-layer δ-doped GaAs with layer-spacing of 100 Å, was observed at ∼895 cm−1. At similar frequency, a plasmon mode was also detected from another GaAs sample with the same δ-doping periods but doubled layer-spacing (200 Å). This provides evidence of spatial quantization of the electron distributions in δ-doped GaAs. The equivalent 3D electron concentration, estimated from the Raman plasmon mode, is ∼1.1×1019/cm3. The presence of the 3D plasmon mode from a quasi-two-dimensional (2D) electron gas is possibly contributed by the electrons in the high energy subbands in the V-shaped potential well of the δ-doped GaAs. The pseudodielectric function <ε>= <ε1>+i<ε2> of this δ-doped GaAs sample was measured by spectroscopic ellipsometry (SE), from an unoxidized surface in an ultrahigh vacuum (UHV) chamber, in the range of 1.5 to 5.0 eV. Compared with uniformly doped GaAs, our SE data indicates a reduced broadening of the optical transitions between the E1 and E1+Δ1, energies due to the δ-doping.
Influence of The Growth Temperature on The Presence of Composition Inhomogeneities in In0.52Al0.48As Layers Grown by MBE on InP Substrates
Authors: Peiro F. , Cornet A. , Hierms A. , Morante J.R. , Georgakilas A. , Halkias G. 
Published: March 2011

ABSTRACTBy using Transmission Electron Microscopy we have studied the presence of composition inhomogeneities in In0.52Al0.48As layers grown on (100) InP. We have found a critical temperature equal to 550°C above which composition inhomogeneities start to appear nonuniformly distributed over the sample area. However, as the growth temperature increases they cover the whole layer. Furtermore, the density of stacking faults and threading dislocations increases for growth temperatures beyond the optimum value of 530°C.
InGaAs/GaAs Quantum Well Structures Grown by Migration-Enhanced Epitaxy
Authors: Wu J.E. , Yoo H.M. , Stoebe T.G. 
Published: March 2011

ABSTRACTGaAs/In.2Ga.8As/GaAs quantum well structures containing InGaAs layers of thickness over and under the critical thickness (hc) were studied, as grown by both conventional molecular beam epitaxy (C-MBE) and migration-enhanced epitaxy (MEE) techniques. A 6.0 monolayer per cycle (ML/cyc) growth rate, in contrast to a one or less-than-one ML/cyc growth rate used in a conventional MEE process, was used to grow In.2Ga.8As layers over hc. As-grown samples were characterized via photoluminescence, X-ray diffraction, and transmission electron microscopy (TEM). The 6.0 ML/cyc MEE-grown layers over hc show superior optical quality to MBE-grown layers with the same thickness. Both X-ray diffraction and TEM microstructure results indicate that the 6.0 ML/cyc MEE-grown In.2Ga.8As layers are still strained layers while those grown by conventional MBE method are not. The 6.0 ML/cyc MEE process seems to be advantageous for growing InGaAs layers over the critical thickness.