bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Studies of Laser Annealed Semiconductors
Authors: Zehner D. M. , White C. W. 
Published: March 2011

ABSTRACTThe surface regions of semiconductor single crystals have been examined following laserannealing in an ultrahigh vacuum environment with the output of a pulsed ruby laser. Atomically clean surfaces with impurity levels below 0.1% of a monolayer can be produced by multiple pulse irradiation. Ordered surface structures are produced on low index oriented crystals as well as crystals slightly misoriented. Metastable surface structures exhibiting (l×1) LEED patterns have been produced on (111) orientations and are believed to be a consequence of the rapid cooling rates of 109 degs/sec achieved with the laser irradiation process. The surface and subsurface regions of ion-implanted Si crystals have been examined both before and after laser irradiation and results obtained from Si samples implanted with As are discussed.
Applications of Laser Annealing in IC Fabrication
Authors: Hess L.D. , Eckhardt G. , Kokorowski S.A. , Olson G.L. , Gupta A. , Chi Y.M. , Valdez J.B. , Ito C.R. , Nakaji E.M. , Lou L.F. 
Published: March 2011

ABSTRACTLaser annealing is discussed in the context of potential applications in the fabrication of advanced solid state components and integrated circuits. General aspects of the uniquetemporal and spatial heating distributions that can be obtained with laser heating are presented, and selected examples are given which illustrate the advantage of special time/temperature heating cycles in the processing of specific semiconductor device structures. The performance of silicon and Hgcdte diodes, polysilicon resistors, multiple stacked polysilicon/oxide capacitors, Al/Si ohmic contacts and MOS/SOS transistors fabricated using laser annealing is significantly improved relative to devices fabricatedusing conventional furnace annealing.
Rapid Thermal Annealing of Silicon Using an Ultrahigh Power Arc Lamp
Authors: Hodgson R. T. , Baglin J. E. E. , Michel A. E. , Mader S. , Gelpey J. C. 
Published: March 2011

ABSTRACTWe have used an ultrahigh power, 100kW vortex cooled arc lamp to anneal As+ implant damage in <100> silicon wafers. When the wafer temperature was held above 1100°C for ∼1sec, TEM analysis indicated that the material was free of extended defects.The dopant diffused much more rapidly than would be expected from the usual models. However, preliminary results indicate that defect free material can be produced with dopant movement limited to ∼100Å.
Flame Annealing of Ion Implanted Silicon
Authors: Narayan J. , Young R. T. 
Published: March 2011

ABSTRACTWe have investigated flame annealing of ion implantation damage (consisting of amorphous layers and dislocation loops) in (100) and (111) silicon substrates. The temperature of a hydrogen flame was varied from 1050 to 1200°C and the interaction time from 5 to 10 seconds. Detailed TEM results showed that a “defect-free” annealing of amorphous layers by solid-phase-epitaxial growth could be achieved up to a certain concentration. However, dislocation loops in the region below the amorphous layer exhibited coarsening,i.e., the average loop size increased while the number density of loops decreased. Above a critical loop density, which was found to be a function of ion implantation variables and substrate temperature, formations of 90° dislocations (a cross-grid of dislocation in (100) and a triangular grid in (111) specimens) were observed. Electrical (Van der Pauw) measurements indicated nearly a complete electrical activation of dopants with mobility comparable to pulsed laser annealed specimens. The characteristics of p-n junction diodes showed a good diode perfection factor of 1.20–1.25 and low reverse bias currents.
Isothermal Annealing of Ion Implanted Silicon With a Graphite Radiation Source
Authors: Wilson S. R. , Gregory R. B. , Paulson W. M. , Hamdi A. H. , Mcdaniel F. D. 
Published: March 2011

ABSTRACTBoth (100) and (111) Si wafers were implanted with As, P or B to doses from 1013 to 1016/cm2 and annealed with a Varian IA-200 isothermal annealer. The anneal occurs in a vacuum using infrared radiation for exposure times of 5 to 30 sec. Sheet resistance (Rs), Hall effect, RBS and SIMS were used to analyze the wafers. For each dopant a decreasing Rs occurs with increasing exposure time until a minimum value is reached. Longer anneals produce increased dopant diffusion, and the Rs for As and P implanted wafers increased unless the wafer was capped with 0.05 μm of SiO2 which prevents a loss of dopant. The results for (100) wafers are better than for (111) with As doses ≤1015/cm2, however at doses >1015/cm2 the (100) and (111) results are comparable. The As implanted, isothermally annealed layers were thermally stable for As concentrations ≤2E 20/cm3.
Gettering of Impurities by Incoherent Light Annealed Porous Silicon
Authors: Borisenko V. E. , Dorofeev A. M. 
Published: March 2011

ABSTRACTThe application of electrochemically formed porous silicon to getter Cu and Au atoms in silicon crystals during incoherent light annealing for 4 to 20 sec is reported. Exposure light power density of 30 W/cm2 was used to heat the samples up to 950 °C. Improvement of lifetime related to Au and Cu gettering with porous silicon has been observed. Excess impurity interstitials and their enhanced diffusion are supposed to be responsible for the gettering effect.
Instability of The Electron-Hole Plasma and its Possible Relation With Melting
Authors: Combescot Monique , Bok Julien 
Published: March 2011

ABSTRACTWe show that the softening of the T.A. phonon mode produces an instability in the electron-hole plasma of a silicon-like semiconductor and suggest that this instability can be the mechanism for melting of this type of material. This allows us to estimate the characteristics of a laser pulse which are necessary to modify the usual melting, i.e. which would lead to a substantial decrease of the melting temperature.
Scanning Eectron Beam Annealing of Oxygen Donors in Czochralski Silicon
Authors: Pollard C J , Speight J D , Barraclough K G 
Published: March 2011

ABSTRACTThe destruction of the oxygen donor complex in Czochralski silicon has been studied using scanning electron beam annealing in the range 550°C to 1050° C for 5s to 1000s. A two stage annealing schedule ensured a rapid rise to the target temperature and overscanning provided a uniform, non-distorting heating field. Four point probe and spreading resistance measurements showed a very rapid donor destruction rate above 650° C; between 550° C and 650°C the lower donor destruction rate allowed a study of the annealing behaviour.
Arsenic Implant Activation and Redistribution in P-Type Silicon Induced by Pulsed Electron Beam Annealing
Authors: Barbierf D. , Baghdadi M. , Laugier A. , Cachard A. 
Published: March 2011

ABSTRACTIn this work Pulsed Electron Beam Annealing has been used to Sctivaye As implanted in (100) and (111) silicon (140 keV- 1015 cm−2 ). With a selected electron beam energy deposition profile excellent regrowth layer quality and As activation has been obtained in the 1.2–1.4 J/cm2 fluence range. As redistribution is conistent with the melting model assuming a diffusivity of 10−4 cm2/s in liquid silicon. As losses might slightly reduce the carrier concentration near the surface in the case of (100) silicon. However a shallow and highly active N+ layer have been achieved with optimized PEBA conditions.
Transient Annealing of Ion-Implanted Silicon Using A Scanning IR Line Source
Authors: Liu Y.S. , Cline H.E. , Possin G.E. , Parks H.G. , Katz W. 
Published: March 2011

ABSTRACTRecent interest in finding an efficient method for transient annealing of ion-implanted silicon has led to studies of various rapid annealing schemes such as graphite heaters and high intensity incoherent light sources as alternative methods to laser annealing. In this paper, we describe a recent study of transient annealing of ion-implanted silicon using a scanning IR line source created by a single tungsten filament enclosed in a quartz envelope. Various dopants (B+, P+ and As+) with fluences of 1014 to 1016 ions/cm2 were implanted and annealed under both transient and steady-state thermal conditions. Dopant depth distributions were analyzed using the SIMS technique. Sheet resistance measurements indicated that almost 100% activations of the implanted dopants were achieved. Sensitivities of dopant activation to transient annealing conditions were studied as a function of dopant concentrations, and high-dose As- and B-implanted samples were found to be sensitive to transient thermal cycle, particularly to the peak temperature. Recrystallization was studied with Rutherford backscattering spectroscopy using 2 Mev He+ ions.
Conduction in Polycrystalline Silicon: Generalized Thermionic Emission-Diffusion Theory and Extended State Mobility Model
Authors: Khondker A.N. , Kim D.M. , Shah R.R. 
Published: March 2011

ABSTRACTWe present a general theory of conduction in polysilicon. The theoretical framework reconciles two apparently divergent approaches for modeling conduction processes in polysilicon and provides a physical basis to correctly interpret and to point out the deficiencies of previously reported thermionic and thermionic field emission theory. This model is based on an extended state mobility in the disordered grain boundary and the thermionic emission-diffusion theory for conduction of current. The attractive features of our theory are (a) it can explain the experimental data without the use of an artificial factor, f, (b) the conduction process is characterized explicitly by the inherent material properties of the grain and the grain boundary. Our model is particularly suited for describing the electrical properties of laser restructured polysilicon, where because of large grain size the diffusion process is expected to be dominant.
Selective Laser Annealing For Device Processing
Authors: Calder I.D. , Naem A.A. , Naguib H.H. 
Published: March 2011

ABSTRACTSelective laser crystallization of undoped polysilicon films has been achieved through the use of a patterned Si3N4 anti-reflection (AR) coating. The recrystallized poly-Si beneath the AR cap exhibits an etch rate 50–90% lower than the surrounding uncapped material, allowing anisotropic etching of poly-Si for the fabrication of MOSFET gates. Undercut is reduced by at least a factor of two from unannealed material. Annealed edge profiles are uniform within ±0.03μm for plasma etching (±0.05 for wet etching) compared to ±0.1μm (± 0.25μm for wet etching) for unannealed regions. The sheet resistivity of 0.5μm films doped by phosphorus diffusion was reduced from an initial value of 82±5 Ω/□ to 40±8 Ω/□ when the dopant was diffused into recrystallized poly-Si and to a final value of 10.2 ± 0.2 Ω/□; after a further laser activation step. Potential applications in VLSIC processing are discussed.
Crystallization of Amorphous Silicon Films by Pulsed Ion Beam Annealing
Authors: Gyulai J. , Fastow R. , Kavanagh K. , Thompson M. O. , Palmstrom C. J. , Hewett C. A. , Mayer J. W. 
Published: March 2011

ABSTRACTRegrowth by pulsed proton beam was studied for evaporated amorphous Si layers, for layers converted to polycrystalline by annealing (both with and without Ge markers) and for implantation-amorphized SOS films. Silicon-on-sapphire showed the lowest threshold for regrowth. Amorphous silicon melted at about 0.2 J/cm2 lower fluences of protons of 380 kev energy than crystalline Si. Implanted Sb into Sos occupies lattice positions exceeding the solid solubility.
Detection of Electronic Defects in Strip-Heater Crystallized Silicon Thin Films
Authors: Johnson N. M. , Moyer M. D. , Fennell L. E. , Maby E. W. , Atwater H. 
Published: March 2011

ABSTRACTElectronic defects in strip-heater crystallized silicon thin films have been investigated with capacitance-voltage (C-V),deep-level spectroscopic, and scanning-electron microscopic techniques. For electrical characterization the crystallized silicon films were used to fabricate inverted metal-oxide-silicon capacitors in which degenerately doped bulk silicon substrates provided the gate electrode. High-frequency C-V characteristics yield effective fixed-charge densities in the oxide of ≤ 2×1011 cm−2. Trap-emission spectra, recorded with deep-level transient spectroscopy on both p-type and n-type capacitors, indicate a continuous distribution of deep levels throughout the silicon bandgap. The Si-SiO2 interface is considered to be the principal source of this deep-level continuum, since the films are essentially single crystal with a low density of subgrain boundaries; the effective interface-state density is ≤ 2.5×1010 eV−1 cm−2. A discrete energy level, detectable above the background continuum,appears in the upper half of the silicon bandgap; it may identify a point defect in the bulk of the silicon film with a spatially uniform density of approximately 1×1013 cm−3. On lateral p-n junction diodes, electron-beam-induced-current images reveal enhanced diffusion of arsenic along structural defects intersecting the junction.
Characterization and Application of Laser Induced Seeded-Lateral Epitaxtal Si Layers on SiO2
Authors: Miyao M. , Ohkura M. , Warabisako T. , Tokuyama T. 
Published: March 2011

ABSTRACTElectrical and crystal properties of seeded lateral epitaxial Si are evaluated as a function of distance from seeding area with the aid of a micro-probe RHEED and MOSFET fabrication. the results indicate that the quality of a grown layer is as good as that of bulk Si Crystal for most of the epitaxial layer. However, at the SiO2 edge, electrial properties are somewhat poor due to the existence of dislocation and residual stress.Element devices useful for SO structures are fabricated. Electrical properties of MOSPET's with double active areas indicate that surface and bottomregions of the epitaxial layer are all of device worthy quality.Insulated control gate bipolar type transistors are proposed and some preliminary results are shown.
Measurement of Fast Melting and Regrowth Velocities in Picosecond Laser Heated Silicon
Authors: Bucksbaum P. H. , Bokor J. 
Published: March 2011

ABSTRACTFast regrowth of amorphous silicon from liquid silicon films has been directly observed in a time resolved picosecond laser melting experiment. Liquid films up to 100 nm thick were formed on crystalline substrates with 15 picosecond 248 nm pulses from a KrF* excimer laser. The film thickness as a function of time was probed directly by observing attenuation of 1.64 pm 15 psec light pulses transmitted through the melt. Melting and regrowth velocities were compared to a heat diffusion model, and evidence for melt undercooling was observed. The resolidified silicon was amorphous at all values of incident laser intensity.
Cw Laser Annealing of Ion Implanted Oxidized Silicon Layers on Sapphire
Authors: Alestig G. , HolmÉn G. , Peterström S. 
Published: March 2011

ABSTRACTCW laser annealing has been performed on silicon on sapphire (SOS) implanted with boron or phosphorus ions to a dose of 1015 ions/cm2 . The laser irradiation was done both with and without an oxide layer on top of the silicon and from both the silicon and the sapphire side. Sheet resistivity and Hall effect measurements were used for the analysis of the samples. Good annealing and high activation of the dopants were obtained for both oxidized and unoxidized SOS. For samples irradiated from the silicon side, the needed laser power changed depending on the thickness of the oxide. For samples irradiated from the sapphire side, the needed laser power was independent of oxide thickness.
The Effects of Selectively Absorbing Dielectric Layers and Beam Shaping on Recrystallization and Fet Characteristics in Laser Recrystallized Silicon on Amorphous Substrates
Authors: Possin G. E. , Parks H. G. , Chiang S. W. , Liu Y. S. 
Published: March 2011

ABSTRACTSelective absorption, using patterned dielectric films, and beam shaping were used as means for improving the recrystallization of LPCVD polysilicon islands on fused quartz. IR imaging of the laser heated region was used to optimize and control the recrystallization. MOSFETs were fabricated in laser-recrystallized silicon islands on amorphous substrates using a standard n-channel poly-gate process. Devices with various channel lengths and widths were fabricated, and the dependence of threshold voltage, channel mobility, and leakage on recrystallization conditions and device dimensions was studied.
Growth of Silicon-on-Insulator Films using a Line-Source Electron Beam
Authors: Knapp J. A. , Picraux S. T. 
Published: March 2011

ABSTRACTA swept line-source electron beam has been used to study unseeded Si-on-insulator crystallization at beam scan speeds of 150–1500 cm/s. For a particular sample configuration a maximum linear crystallization velocity of ~ 350 cm/s was observed. At higher sweep speeds, competing nucleation occurred at intervals across the film. Both the limit in crystallization velocity and the intervals between nucleation are tentatively explained by a simple model.
Time Resolved Measurements of Interface Dynamics During Pulsed Laser Melting Observed by Transient Conductance
Authors: Thompson Michael O. , Galvin G. J. 
Published: March 2011

ABSTRACTThe transient conductance technique has been used in a detailed study of the liquid-solid interface dynamics during pulsed laser melting of Si and silicon-on-sapphire. Average melt and regrowth velocities, as well as the maximum melt depth, can be obtained with the technique. The measurements are found to agree well with a computer simulation based on a thermal model of the melt and subsequent solidification. The melt-in velocity has been observed to exceed 200 m/sec. Under 2.5 ns UV irradiation, the critical velocity for amorphization of <100> Si has been measured at 15 m/sec.
Lateral Epitaxial Growth of Thick Polysilicon Films on Oxidized 3-Inch Wafers
Authors: Celler G. K. , Robinson Mcd. , Lischner D. J. , Sheng T. T. 
Published: March 2011

ABSTRACTRecently we reported the first successful crystallization from the melt of 15,μm thic Si films on SiO2. In this technique of Lateral Epitaxial Growth over Oxide (LEGO), crystallization is initiated at seeding vias in SiO2 and propagates over the amorphous insulator, resulting in high structural quality of the grown film. Uniform and bow-free crystallization of complete 3-inch wafers occurs in <60 sec in a special furnace, with wafers placed between a bank of high intensity tungsten halogen lamps and a water cooled base.In this paper we provide further details of crystallization procedure and new structural characterization data. The mechanism of LEGO crystallization and its limitations are also discussed.
Crystallization of Silicon Films on Glass: A Comparison of Methods
Authors: Lemons Ross A. , Bosch Martin A. , Herbst Dieter 
Published: March 2011

ABSTRACTThe lure of flat panel displays has stimulated much research on the crystallization of silicon films deposited on large-area transparent substrates. In most respects, fused quartz is ideal. It has high purity, thermal shock resistance, and a softening point above the silicon melting temperature. Unfortunately, fused quartz has such a small thermal expansion that the silicon film cracks as it cools. This problem has been attacked by patterning with islands or moats before and after crystallization, by capping, and by using silicate glass substrates that match the thermal expansion of silicon. The relative merits of these methods are compared. Melting of the silicon film to achieve high mobility has been accomplished by a variety of methods including lasers, electron beams, and strip heaters. For low melting temperature glasses, surface heating with a laser or electron beam is essential. Larger grains are obtained with the high bias temperature, strip heater techniques The low-angle grain boundaries characteristic of these films may be caused by constitutional undercooling. A model is developed to predict the boundary spacing as a function of scan rate and temperature gradient.
Electrical Defect Analysis Following Pulsed Laserirradiation of Unimplanted GaAs
Authors: Pribat D. , Delage S. , Dieumegard D. , Croset M. , Srivastava P.C. , Bourgoin J.C. 
Published: March 2011

ABSTRACTCurrent-voltage, capacitance-voltage and defect spectroscopy techniques are used to characterize the electrical properties of GaAs crystals after pulsed laser irradiation with either a Nd-YAG or a Ruby laser. I(V) and C(V) measurements performed in conjunction on Au/GaAs Schottky structures after laser irradiation at low energy density show an important barrier lowering, of the order of 300mV. Carrier compensation up to 6×lO16/cm3 is observed in a subsurface layer whose thickness increases with deposited laser energy density. D.L.T.S. is used to study the tail of laser induced defects behind the heavily compensated layer. Finally the results are compared to those obtained following conventional thermal treatment.
Transient Conductivity Measurements in Pulsed Ion Beam Melted Silicon
Authors: Fastow R.M. , Gyulai J. , Mayer J.W. 
Published: March 2011

ABSTRACTA pulsed proton beam, ˜200 ns in duration, has been used to melt and regrow single crystal silicon. The protons had an energy of 300 kev, yielding a measured energy density of 0.8–2.0 J/cm2. The method of transient conductivity has been used to determine the melt depths, melt durations, and regrowth velocities. The measured values for 2.0 J/cm2 were, respectively, 1.7 μm, 2 μsec, and 1.4 m/sec.Computer generated melt curves were compared to experiment with good agreement. The energy required to initiate melt was determined, and a linear dependence of melt depth with energy has been observed.
Pulsed Proton Beam Annealing of Co-Si Thin Film Systems
Authors: Chen L. J. , Hung L. S. , Mayer J. W. , Baglin J. E. E. 
Published: March 2011

ABSTRACTCobalt (∼300Å) and CoSi2 (∼1000Å) thin films on Si have been annealed by intense proton beams. RBS and TEM were performed to study ion beam annealing effects.For ion beam energy densities above about 1 J/cm2, epitaxial CoSi2 layers were formed for both Co and polycrystalline CoSi2 on Si. At low energy densities, Co2Si was found to coexist with Co. The results are discussed in terms of eutectic melting processes.
Submicron Conductor Array Fabricated from a Recrystallized Eutectic Thin Film
Authors: Cline H. E. 
Published: March 2011

ABSTRACTA submicron conductor array was fabricated without using lithography by selectively etching a recrystallized A1-A12Cu eutectic alloy thin film. The 2 micron thick eutectic films were deposited on glass substrates and directionally solidified with both a quartz-iodine lamp and a scanning laser at rates between .0016 and .14 cm/sec. The resulting structure consisted of alternate parallel stripes of the two eutectic phases with a spacing between .5 and 4 microns that was controlled by the solidification rate. An array of submicron Al- rich conductors was fabricated by selectively etching away the Al2 Cu phase. At solidification rates greater than .004 cm/sec using the lamp heater the solid-liquid interface became non-planar while with the laser the structure was well alligned at the highest rates used, .14 cm/sec. At the maximum theoretical solidification rate that produces a two phase aligned eutectic structure the width of the Al wires would be 100A.
Amorphous Phase Trapping as a Result of Pulsed Laser Irradiation of Silicon
Authors: Wood R. F. 
Published: March 2011

ABSTRACTIt is concluded that large interface undercoolings of ˜ 300 deg are not likely to occur during pulsed laser annealing and that the observed liquid to amorphous phase transition is not a purely thermodynamic effect. It is then shown that the formation of the amorphous phase can be understood on the basis of a kinetic rate model which makes large undercoolings of the interface unnecessary.