bluuebunny/crossref_metadata_2025_split huggingface dataset:
HI/H2 ECR Plasma Etching of III-V Semiconductors
Authors: Pearton S. J. , Chakrabarti U. K. , Katz A. , Ren F. , Fullowan T. R. , Abernathy C. R. , Hobson W. S. 
Published: March 2011

ABSTRACTHI/H2/Ar discharges are shown to be universal etchants for rn-V semiconductors, giving rise to highly anisotropic features with smooth surface morphologies. At loy dc self bia:s (-100V) and low pressure (1 mTorr), etch rates for all III-V materials of >2000Å min−1 are possible for high HI percentages in the discharges, whereas rates greater than 1 Åm min−1 are obtained at higher pressures and dc biases. These etch rates are approximately an order of magnitude faster than for CH4/H2/Ar mixtures under the same conditions and there is no polymer deposition on the mask or within the reactor chamber with HI/H2/Ar. Auger Electron Spectroscopy reveals residue-free, stoichiometric surfaces after dry etching in this mixture. As i result, photoluminescence intensities from dry etched samples remain high with little apparent damage introduction. Changes in the near-surface carrier concentration due to hydrogen passivation effects are also negligible with HI-based mixtures in comparison to CH4-based dry etching.
A Photoluminescence Investigation of Ion Beam and Electron Cyclotron Resonance ETCH-Induced Damage on GaAs/AlGaAs Multi Quantum Well Structures
Authors: Bensaoula A.H. , Bensaoula A. , Freundlich A. 
Published: March 2011

ABSTRACTThe presence of highly energetic ionic and neutral species during dry etching generates damage in device structures which significantly reduces their performance. In this study we have utilized photoluminescence spectroscopy (PL) on GaAs/AlGaAs Multi Quantum Well (MQW) structures to assess and compare the relative damage induced by the standard ion beam etch technique and the “less damaging” newer Electron Cyclotron Resonance (ECR) etch technique. MQW structures with well widths of 2.7, 6.4, 10.8, and 81 nanometers (nm) at a distance from the sample surface of 40.5, 83, 130, and 170 nm respectively were grown by molecular beam epitaxy. In order to minimize the effect of the radically different chemistries present in reactive ion etching and in ECR reactive etching we have chosen to initially compare the damage-induced luminescence degradation resulting from Ar irradiation only. The PL intensity is shown to correlate well with the ion dose and energy. At equivalent total surface erosion under Ar irradiation the ECR process is shown to cause significantly less deterioration on QW PL yield. In the ion beam case a dose corresponding to a surface sputtering of less than 100 angstroms of the AlGaAs barrier causes total extinction of the PL from the QW lying at 1000 angstroms below the surface. By comparison under similar conditions no degradation is detected in the ECR irradiation case. Even at higher ECR doses equivalent to removal of up to 30 nm from the top AlGaAs barrier layer only minimal degradation is observed.
Lattice Parameter Changes in High Dose Ion-Implanted, Pulsed Laser Annealed GaAs:Si
Authors: Compaan A. , Yao H.D. , Adams P.M. , Knudsen J.F. 
Published: March 2011

ABSTRACTDouble crystal x-ray diffraction has been used to examine the lattice parameter changes which occur in heavily Si-doped GaAs obtained by ion implantation of 28Si at 180 keV with doses up to 1 x 1016/cm2. The heavily damaged, implanted layer was pulsed laser annealed with single pulses from a 10 ns dye laser operating at 728 nm with an energy density of up to 0.9 J/cm2. Plasmon Raman scattering was used at the center of the laser-annealed spots to determine the free electron concentration which reached ∼4 × 1019/cm3. Double crystal rocking curves were obtained for <400> reflections from the pulsed laser annealed area and from the surrounding as-implanted region. The results show a dilation of the lattice of up to 0.5% in the as-implanted region and in the laser-annealed region a dilation of 0.025%. The residual lattice dilation after annealing is interpreted in terms of a dilation due to free carriers and a (smaller) contraction due to the Si atomic size effects.
Evidence for Vacancy Clustering in Silicon Implanted Indium Phosphide
Authors: Schultz Peter J. , Simpson P.J. , Akano U.G. , Mitchell I.V. 
Published: March 2011

ABSTRACTDamage induced in InP wafers by ion implantation has been investigated using Doppler broadening of annihilation radiation from variable-energy positrons (VEP), Rutherford backscattering/channeling (RBS), and room temperature photoluminescence (PL). Si* ions were implanted at 600 keV incident energy to total fluences from 1011 to 1014 ions cm−2. Annealing at room temperature was monitored for ∼100 days, during which both VEP and RBS showed recovery of the crystal toward the pre–implanted condition. RBS measurements of samples annealed at elevated temperatures showed that full restoration of lattice order occurred at 375 K, but VEP data for isochronal annealing up to 720 K showed only a moderate reduction in the vacancy–type defect concentration with a significantly narrower lineshape, consistent with vacancy clustering. PL measurements for MOCVD grown InP layers annealed up to 1100 K after implantation also indicated only moderate defect reduction.
Low Energy Ion Beam Modification of AlNxOy Thin Film for Insulated Gate Field Effect Transistors
Authors: Chan James S. , Cheung Nathan W. , Yu Kin Man 
Published: March 2011

ABSTRACTNitrogen ion implantation was performed to enhance the nitrogen content of non-stoichiometric AlNXOY film (x < 1.0), which was prepared via reactive RF sputtering. A method called plasma immersion ion implantation (P111) was employed to perform the nitrogen implants. The implanted films were studied for changes in film composition using Rutherford Backscattering (RBS). Optical absorption behavior of the films was analyzed using a Perkin-Elmer monochrometer, and electrical characteristics were measured using both high frequency capacitance-volltage (CV) and current-voltage (IV) measurements. The implanted films were subsequently rapid thermal annealed in a nitrogen atmosphere from 550°C to 1060°C, and the resulting effects on the AlNXOY film were investigated using the aforementioned techniques.
Titanium Surface Hardening by Pulsed Nitrogen Ion Implantation
Authors: Feugeas Jorge , Sanchez G. , Grigioni G. , de Gonzalez C.O. 
Published: March 2011

ABSTRACTLayers of TiN have been developed on pure titanium samples using pulsed ion beams generated with a Plasma Gun operated in the detonation mode.XPS analyses show TiNx formation in depths >0.6μm, with stoichiometric x>0.8. The efficient TiN formation in this process can be attributed to the fast energy released by the pulsed beams, which can increase the surface layer temperatures at a ∼15K/ns rate, generating thermal gradients of ∼1500K/μm. This thermal effect can help the titanium getter effect on the nitrogen plasma bubble.
Oxide Degradation Effects in Dry Patterning of Resist Using Neutral Oxygen Beams
Authors: Mlynko Walter E. , Kasi Srinandan R. , Manos Dennis M. 
Published: March 2011

ABSTRACTNovel processing methods are being studied to address the highly selective and directional etch requirements of the ULSI manufacturing era; neutral molecular and atomic beams are two promising candidates. In this study, the potential of 5 eV neutral atomic oxygen beams for dry development of photoresist is demonstrated for application in patterning of CMOS devices. The patterning of photoresist directly on polysilicon gate layers enables the use of a self-contained dry processing strategy, with oxygen beams for resist etching and chlorine beams for polysilicon etching. Exposure to such reactive low-energy species and to the UV radiation from the line-of-sight, high-density plasma source can, however, alter MOSFET gate oxide quality, impacting device performance and reliability. We have studied this process-related device integrity issue by subjecting polysilicon gate MOS structures to exposure treatments of 5–20 eV oxygen beams similar to those used for resist patterning. Electrical characterization shows a significant increase in the oxide trapped charge (30–90x) and interface state density (30–60x) upon low-energy exposure. Current-voltage(IV) and dielectric breakdown characterization show increased low-field leakage characteristics for the same exposure. High-field electron injection studies reveal that the 0.25–V to 0.5–V negative flatband shifts (measured after oxygen beam exposure) can be partially annealed by carrier injection. This could be due to positive charge annihilation or electron trapping, or some combination of both. SEM and electrical analysis of structures exposed to neutral beam processing are presented along with the results of thermal annealing treatments.
Formation of Defects During Ion-Assisted Growth of Thin Films from the Vapor Phase
Authors: Sundgren J-E , Hultman L , Håkansson G , Birch J , Petrov I 
Published: March 2011

ABSTRACTDuring ion-assisted growth of thin films from the vapor phase, defect generation and incorporation are of paramount interest. In many cases the wish is to obtain as defect free films as possible, however, in some applications a certain, controllable, defect content is desirable. In this paper experimental results on defect incorporation as a function of ion energy and growth temperature are presented. Results for poly- and single crystalline TiN films as well as for epitaxial Mo/V superlattice films are given. As the ion energy and/or ion flux are increased the amount of defects increases. At low temperatures the defects consist predominantly of point defect clusters and incorporated primary ions while at higher temperatures redistribution of point defects and incorporated primary ions results in dislocation loops and gas bubbles, respectively. However, for low ion energies where the energy transferred to the growing film surface is not high enough to cause atomic displacement events, reduction of defect densities can also be obtained. Furthermore, in the case of Mo/V superlattices it is demonstrated that interfacial mixing and increased interface roughness occurs at ion energies ≥ 25 eV. In the absence of an applied substrate bias the interface widths are determined to be 0.3 nm. For higher energies the widths becomes progressively larger and at a bias of 225 V an interface width of > 0.9 rum is obtained.
Role of Kinetic Energy of Sputtered Particles in Thin Film Properties
Authors: Taga Yasunori 
Published: March 2011

ABSTRACTThe thin film processes of the sputter deposition method have been reviewed with special emphasis on the effects of kinetic energy of sputtered particles and ion bombardment during deposition on thin film properties. An overview is first given to describe the thin film process and ion-surface interactions, where the methods of measuring the energy distribution of sputtered ions and the anisotropic-emission-effect sputter deposition are presented. Experimental results for Cr, SiO2 and Ni-Si-B films are presented, and the correlation between the structure and properties of the thin films is discussed. Research in modification of thin films by energetic atoms and ions is an exciting area of materials science in the future.
Ion-Induced Surface Modification of Alloys
Authors: Wiedersich H. 
Published: March 2011

ABSTRACTIn addition to the accumulation of the implanted species, a considerable number of processes can affect the composition of an alloy in the surface region during ion bombardment. Collisions of energetic ions with atoms of the alloy induce local rearrangement of atoms by displacements, replacement sequences and by spontaneous migration and recombination of defects within cascades. Point defects form clusters, voids, dislocation loops and networks. Preferential sputtering of elements changes the composition of the surface. At temperatures sufficient for thermal migration of point defects, radiation-enhanced diffusion promotes alloy component redistribution within and beyond the damage layer. Fluxes of interstitials and vacancies toward the surface and into the interior of the target induces fluxes of alloying elements leading to depthdependent compositional changes. Moreover, Gibbsian surface segregation may affect the preferential loss of alloy components by sputtering when the kinetics of equilibration of the surface composition becomes competitive with the sputtering rate. Temperature, time, current density and ion energy can be used to influence the individual processes contributing to compositional changes and, thus, produce a rich variety of composition profiles near surfaces.
Second Phase Formation in Aluminum annealed after Ion Implantation with Molybdenum.
Authors: Bentley J. , Stephenson L. D. , Benson R. B. , Parrish P. A. , Hirvonen J. K. 
Published: March 2011

ABSTRACTThe microstructure of aluminum annealed after implantation to peak concentrations of approximately 4.4 and 11 at. % Mo was investigated by analytical electron microscopy. Al12Mo precipitates formed with pseudo-lamellar and continuous film microstructures. Video recordings of insitu annealing experiments revealed the details of the phase transformations.
High-Density Cascade Effects in Ion-Implanted Ag-Au Alloy
Authors: Vozzo F. R. 
Published: March 2011

ABSTRACTHigh-purity, polycrystalline foils of 12 atomic percent gold Ag-Au alloy were implanted with polyatomic ions of arsenic and antimony at energies of 45 keV per atom. During fluence intervals before and after the steady state, sputtered material was collected on high-purity strips of aluminum foil. Subsequent backscattering analysis of the targets and collectors showed that significant redistribution and segregation occurred in the implanted layer, with relative depletion of silver consistently observed. The results suggested that preferentiality in sputtering is dependent on composition of an alloy and the ion beam used (even at low fluence), but there appears to be no major difference between the redistribution behavior of targets sputtered with atomic ions and equal-velocity molecular ions.A model is presented which predicts the sputtering behavior and surface configuration of a binary alloy implanted to steady state with a third species.
The Production of Porous Structures on Si, Ge and GaAs by High Dose Ion Implantation.
Authors: Williams J.S. , Chivers D.J. , Elliman R.G. , Johnson S.T. , Lawson E.M. , Mitchell I.V. , Orrman-Rossiter K.G. , Pogany A.P. , Short K.T. 
Published: March 2011

ABSTRACTThis paper presents new data on the previously observed porous structures which can be developed in high dose, ion implanted Ge. In addition, we provide strong evidence to suggest that such porous structures can be formed in high dose, ion implanted Si and GaAs substrates under particular implant conditions. Comparison of the various systems using RBS analysis indicates that heavy ion doses as low as 1014 cm−2 can give rise to such structural modifications in GaAs, whereas doses of 1015 cm−2 are needed to observe an effect with Ge and doses usually exceeding 1016cm−2 are required for Si.
Thermodynamics and Kinetics of Crystallization of Amorphous Si and Ge Produced by Ion Implantation
Authors: Donovan E.P. , Spaepen F. , Turnbull D. , Poate J.M. , Jacobson D.C. 
Published: March 2011

ABSTRACTAmorphous Si and Ge layers, produced by noble gas (Ar or Xe) implantation of single crystal substrates, have been crystallized in a differential scanning calorimeter (DSC). This technique allows determination of the growth velocity (which is proportional to the rate of heat evolution, ΔHac), and the total enthalpy of crystallization ΔHacAmorphous Ge was found to relax continuously to an amorphous state of lower free energy, with a total enthalpy of relaxation of 6.0 kJ.mole−1 before crystallization started. The regrowth velocity on (100) substrates,measured to be 4.2×1017 exp (−2.17eV/kT)Å/sec, is compared to other determinations. The value of ΔHac was found to be 11.66± 0.7 kJ.mole, in good agreement with ΔHac for amorphous Ge produced by other methods. For Si, ΔHac was determined to be 11.95± 0.7 kJ.mole without any evidence of heat release due to relaxation. The kinetics of crystallization measured by DSC are compared with those determined by other techniques. The effects of the implant profile on the regrowth velocity could also be observed directly in the DSC signal. The more accurate value of ΔHac allowed a more precise determination of the melting temperature of amorphous Si: Taℓ= 1420K.
Physical Properties of Two Metastable States of Amorphous Silicon
Authors: Hubler G.K. , Waddell C.N. , Spitzer W.G. , Fredrickson J.E. , Kennedy T.A. 
Published: March 2011

ABSTRACTCharacterization of the two metastable states of amorphous Si produced by ion implantation is extended to include electron paramagnetic resonance, fundamental absorption edge, and density measurements in addition to infrared reflection. It is found that the properties of the two a-Si states are not dependent upon the mass of the incident ion (12C, 29Si, 31p, 120Sn) or upon the anneal temperature for 400°≤TA≤600°C. The dangling-bond density drops about a factor of 2, the absorption coefficient drops by more than a factor of 5, but the density does not change when the a-Si makes a transition between the two states.
Megavolt Bioron and Arsenic Implantation into Silicon
Authors: Byrne P.F. , Cheung N.W. , Tam S. , Hu C. , Shib Y.C. , Washburn J. , Strathman M. 
Published: March 2011

ABSTRACTFormation of buried p-type and n-type layers in (100) silicon has been accomplished by implanting with 4 MeV boron and 11 MeV arsenic ions respectively. The projected range (Rp) of 4 MeV boron is 5.2 microns with a straggle (ΔRp) of .2 microns. The 11 MeV arsenic implant has a Rp of 4.37 microns with a ΔRp of .37 microns. The 4 MeV boron implant was carried out to a dose of l×1015/ cm2 while the 11 MeV arsenic implant dose was 1.9×1015/ cm2. For both dopants the target holder could be cooled with either liquid nitrogen (LN) or flowing room temperature water (RT). Buried amorphous regions are seen by cross sectional transmission electron microscopy (XTEM) for both boron and arsenic when LN cooling is used. Arsenic shows a buried amorphous region for the RT case as well. The extent of the buried amorphous regions are compared with the energy deposited into nuclear stopping as determined by computer simulation. Threshold levels are determined for the creation of these buried amorphous regions. The boron samples were annealed for 30 minutes at 900°C in a nitrogen ambient, and XTEM shows no residual damage for both cooling conditions. The arsenic samples underwent a two step annealing procedure; 545°C for 16 hours followed by a 945°C step for 15 minutes. Regions containing dislocation networks are observed by XTEM for both cooling conditions.The 4 MeV implanted boron buried layer was applied to an NMOS process. Transistors fabricated above the p-type buried layer show channel mobility, threshold voltage, and sub-threshold leakage which are indistinguishable from transistors fabricated without the buried layer. Vertical npn bipolar transistors have been fabricated using the 11 MeV arsenic buried layer to form the collector. Electrical characteristics from both these devices indicate that megavolt ion implantation can be applied to silicon for active device geometries.
A Review of Silicon-On-Insulator Formation by Oxygen Ion Implantation
Authors: Pinizzotto Russell F. 
Published: March 2011

ABSTRACTSilicon-on-Insulator structures will be an important technological advance used in future VLSI, VHSIC and threedimensional integrated circuits. The most mature SOI technology other than silicon-on-sapphire is SIMOX, or Separation by Implanted Oxygen. High energy oxygen ions are implanted into single crystal silicon until a stoichiometric buried silicon dioxide layer is formed. After implantation, the material is annealed at high temperature to remove implantation induced defects. The structure is completed by the growth of a thin epitaxial silicon layer. Devices and complex circuits have been successfully fabricated by several research groups. This paper reviews the development of this buried oxide SOI technology from 1973 to 1983. The five major sections discuss the advantages of SOI, the basics of buried oxide formation, the literature published between 1973 and 1983, key issues that must be solved before large scale implementation takes place and, finally, predictions of future developments.
Characterisation of Device Grade Soi Structures formed by Implantation of High Doses of Oxygen
Authors: Hemment P.L.F. , Maydell-Ondrusz E.A. , Stephens K.G. , Arrowsmith R.P. , Glaccum A.C. , Kilner J.A. , Butcher J.B. 
Published: March 2011

ABSTRACTSOI structures have been formed in (100) silicon by implanting 400 keV molecular oxygen to a dose of l.8×l018 O atoms cm−2. These samples were annealed at 1150°C for 2 hours with a SILOX cap. Oxygen depth profiles have been determined by SIMS and wafers implanted at about 500°C have been characterized by studying the regrowth kinetics, As drive in and oxidation rate in the top silicon overlay.
Point defect Supersaturation and Enhanced Diffusion in SPE Regrown Silicon.
Authors: Pennycook S. J. , Narayan J. , Holland O. W. 
Published: March 2011

ABSTRACTTransient, greatly enhanced diffusion has been observed on annealing solid-phase-epitaxial (SPE) grown Si-Sb alloys. This is shown to be due to a high concentration of interstitials being trapped during SPE regrowth. The migration enthalpy, for diffusion of Sb by an interstitialcy mechanism was measured as 1.8 ± 0.2 eV. The interstitials eventually condensed into loops, marking the end of the transient. In a SPE grown Si-Bi alloy a similar transient enhanced diffusion was observed, with an activation energy of 2.0 ± 0.2 eV, but no loops formed.
Investigation of a Thermal Spike Model for Ion Mixing of Metals with SI
Authors: Shreter U. , So Frank C.T. , Paine B. M. , Nicolet M-A. 
Published: March 2011

ABSTRACTA Model for Ion Mixing of Bilayer systems in a thermal spike is described. Normal thermal reactions, at a constant average temperature, are assumed for the duration of the spike. New experimental results on mixing of a Nb/Si couple with Xe ions are shown to agree with the prediction of the model that the apparent activation energy in ion mixing can depend upon the ion species. Calculations of spike mixing for Cr and Ni with Si are presented which show that a substantial part of the experimentally observed mixing rates, and their temperature dependence, can be attributed to thermal spike effects.
Comparison of Heat-Pulse and Furnace Isothermal Anneals of Be Implanted InP
Authors: Molnar B. , Kelner G. , Ramseyer G.L. , Morrison G.H. , Shatas S. C. 
Published: March 2011

ABSTRACTAnnealing in the 600–900°C temperature range, using either a halogen lamp for periods of seconds or a furnace for periods of minutes, has been applied to activate Be implanted InP samples. The Be was ion-implanted at room temperature into InP substrates. The substrates were uncapped and in close contact with another smooth surface during annealing.It was found that in the 1017–1019/cm3 range, the acceptor concentration increased with the temperature of anneal. It was also found that redistribution effects decreased with decreasing anneal time. For short anneals, the optimum condition for an 80–90% activation in the 1017–1018/cm3 range was estimated to be 10 seconds at 950°C. It was also found that after rapid anneal, the carrier concentration profile closely approximated the asimplanted Be profile. In the case of 1018–1019/cm3 implants, which were rapidly annealed, there was a low concentration component (1016–1017/cm3) to the redistribution; this ancillary component to the main active distribution was detected by SIMS and was electrically inactive. For long term annealing this electrically inactive Be component was partly converted to substitutional Be and became electrically active. Rapid thermal annealing eliminated this conversion.