Boron Cluster Ions Research Articles

Infrared Semiconductor Laser Annealing Used for Formation of Shallow Junction

ABSTRACTWe report continuous-wave (CW) infrared-semiconductor laser annealing of silicon implanted with boron atoms with assistance of diamond-like carbon (DLC) films as optical absorption layer in order to form shallow junctions. BF2 ions were implanted at 10 keV at doses of 1.5×1015 cm−2 thorough an 8-nm thick SiO2 layer. The effective boron dose implanted into silicon was 7.5c1015 cm−2 a half of the implantation dose. The initial boron distribution had a peak concentration of 6×1020 cm−3 at the silicon surface and a concentration of 1×1019 cm−3 at a depth of 27 nm. The samples were coated with 200-nm-thick DLC films. The samples were annealed by irradiation with a 940 nm continuous wave laser at 80 kW/cm2 with a beam diameter of 180 μm for 2.6 ms. Heat flow analysis estimated that the sample surface was heated to 1350°C for 1.5 ms by laser annealing. Laser annealing markedly reduced the sheet resistance to 531 Ω/sq. Boron atoms were almost completely activated with a carrier density close to the effective boron dose of 7.5×1014 cm−2. The in-depth profile of boron concentration hardly changed within 3 nm for laser annealing for 2.6 ms. The intermediate SiO2 layer effectively blocked carbon incorporation to a level below 1017 cm−3. These results show that the present laser annealing method is suitable to form shallow junction of a high dopant activation ratio. We will report low energy implantation of boron-cluster ions followed by the present infrared-semiconductor laser annealing in order to form a shallow junction with a depth less than 15 nm.

Molecular dynamic simulation on boron cluster implantation for shallow junction formation

Boron cluster ion implantation is a potential technology for shallow junction formation in integrated circuits manufacture. A molecular dynamic method for cluster implantation simulation, aiming at microelectronics application, is presented in this paper. Accurate geometric structures of boron clusters are described by the model, and the H atoms in clusters are included. A potential function taking the form of combining the ZBL and the SW potentials is presented here to model interaction among the atoms in the boron cluster. The impact of these models on cluster implantation simulation is investigated. There are notable impact on dopant distribution and amount of implantation defects with consideration of these models. The simulation on the distributions of B and H are verified by SIMS data.

Ultra-high resolution mass spectroscopy of boron cluster ions

Boron clusters have recently received considerable attention as a possible solution to the throughput dilemma associated with ultra-low energy (sub keV) p-type source drain extension implants required by cutting edge complimentary metal–oxide semiconductor (CMOS) technology. Boron cluster ion beams contain many masses due to the binomial distribution of the two naturally occurring isotopes (masses 10 and 11) of boron. The broadness of the mass distribution peak in the dispersive plane is further complicated by a plurality of ion states, due to the varying number of hydrogen atoms remaining attached to the borohydride molecule when it is ionized.The B18Hx+ cluster ion mass spectrum from an electron impact ionization source will be analyzed in detail. An ultra-high resolution mass spectrum, exhibiting 1 AMU resolution of a mass 220 cluster ion will be shown. It will be compared to high-resolution spectra of decaborane (B10H14) cluster ions obtained from natural abundance decaborane and from isotopically enriched material.The deconvolution of the binominal distribution from ion states present in the cluster ion beam reveals the hydrogen distribution function. The hydrogen distribution functions as well as the binomial distributions will be presented and discussed. Physical models will be presented that explain the origin of hydrogen distribution function for these high mass borohydride cluster ions.This ultra-high mass resolution is usually unavailable to the ion implant community, however our 120° mass analyzing magnet and the extremely low emittance of the ion beam extracted from the ClusterIon® source coupled with a variable width beam defining aperture and variable width mass defining slits allow for superior mass resolution.

Boron cluster ions from source of negative ions by cesium sputtering

One of the ion implantation challenges for shallow junction formation is the production of high beam current at very low energy. Implantation of boron-containing clusters, such as B n , SiB n , GeB n and B 10H 14 is a potential solution for this problem. Due to the higher cluster ion energy for the lower partial energy of the boron atom, the space-charge limit to the transport of the boron-containing cluster ion beams can be reduced by a factor of M/ m, where M and m are the masses of the cluster and the boron atom, respectively. For a cluster of n boron atoms, the total gain in the cluster beam transport is n× M/ m. In this paper, we will present new data on the extraction of boron-containing clusters with a Source of Negative Ions by Cesium Sputtering. For some clusters, the ion beam current can be increased by 1 to 2 orders of magnitude by adjusting the source parameters. Our experience in the successful extraction of boron-containing clusters may be useful in the design of high current ion sources.

Defect characteristics by boron cluster ion implantation

Cluster ion implantation using decaborane (B 10H 14) has been proposed as a shallow implantation technique for LSI devices with gate lengths of several-tens nanometers. Experiments and computer simulations of low-energy boron monomers and decaborane clusters implantation were performed. Molecular dynamics simulations of B 10 cluster implantation have shown similar implant depth but different damage density and damage structure compared to monomer (B 1) ion implantation with the same energy-per-atom. For monomer implantation, point-defects such as vacancy–interstitial pairs are mainly formed. On the other hand, B 10 generates large numbers of defects within a highly-amorphised region at the impact location. This difference in damage structure produced during implantation is expected to cause different annihilation processes.

Cluster-ion implantation: An approach to fabricate ultrashallow junctions in silicon

Cluster-ion implantation in combination with two-step annealing is effective in making ultrashallow junctions. We have demonstrated the use of heavy atom–boron cluster ions to effectively reduce the boron energy for shallow-junction formation. SiB, SiB2, and GeB cluster ions have been used to produce 2 keV boron for low-energy ion implantation. We have generated the SiB, SiB2, and GeB cluster ions using the source of negative ions by cesium sputtering ion source. Shallow junctions have been made by SiB, SiB2, and GeB cluster ions implanted into Si substrates at 1×1015/cm2 with energies at 6.88, 8.82, and 15 keV, respectively. We also discussed the benefit of a 550 °C preannealing before a 1000 °C, 10 s rapid thermal annealing.

Energy-loss of swift boron and carbon clusters in solids

Inelastic energy losses of boron and carbon cluster ions penetrating carbon foils were theoretically investigated based on the wave packet model. The response of the target electrons are treated dynamically via the dielectric function for the conduction- and the shell-electrons. In this model, we took into account both the spatial size of the bound electrons and the degree of ionization of the individual ions. The former was estimated in a Thomas–Fermi–Moliere statistical manner. The latter was determined by an empirical velocity-dependent formula. The time evolution of the internuclear separations due to Coulomb explosion in a solid was estimated using a standard molecular dynamics calculation. The calculated energy losses showed the cluster effect, which is in good agreement with the existing data.

Interaction of small boron cluster ions with HF

A combined experimental and theoretical study of the reactivity of small boron cluster cations with HF is reported on in this article. Cross sections for the reaction of mass-selected boron (Bn+, n=2–14) and boron monohydride (BnH+, n=4, 7, and 10) cluster ions with HF are reported for collision energies from 0.1 to 10 eV. The reaction proceeds via a chemically bound intermediate complex, and the major product channels involve elimination of BF or H from the BnHF+ intermediate. Both reactivity and product branching depend strongly on cluster size. Reactivity at low energies generally decreases with increasing size, with the appearance of significant bottlenecks to reaction. The effect of adding a hydrogen atom to the reactant clusters was examined for several cluster sizes. In contrast to the boron oxides, hydrogenation of elemental boron cluster ions has little effect on reactivity with HF, suggesting that H does not compete effectively for HF binding sites. The results provide a sensitive test for the accuracy of ab initio calculations on Bn+ and BnH+ and BnF+, and the calculations provide insight into the reaction mechanism and effects of cluster structure on reactivity.

Reactions of boron cluster ions (B+n, n=2–24) with N2O: NO versus NN bond activation as a function of size

Cross sections for reaction of mass-selected boron cluster ions (B+n, n=2–24) with N2O are reported for collision energies from 0.1 to 10 eV. The major product channels are addition of a single nitrogen or oxygen atom to the intact cluster ion. For small clusters, there are no activation barriers and cross sections are large, however, as cluster size increases, bottlenecks and activation barriers reduce reactivity substantially. Significant size effects are observed in the product branching distributions. The dominant reaction mechanism at low collision energies is proposed to be complex formation, where only one bond in N2O is broken, followed by desorption of the stable leaving group (N2 or NO). Reactions with boron cluster ions larger than 16 atoms in size have been studied for the first time, and in addition, supporting evidence is given for our previous suggestion that B3 has an anomalously high ionization potential. Comparisons are made with other oxidation reactions of boron cluster ions, and with aluminum and silicon cluster ion reactions with N2O.

Boron cluster ion oxidation: Reactions with CO2, dissociation of boron cluster oxide (BnO+) ions, and sequential oxidation

Cross sections for oxidation reactions of boron cluster ions (B+1–14) with CO2 are reported as a function of collision energy. The results give insight into the oxidation mechanism and are a sensitive probe of the B+n–O bond energy. In addition, collision-induced dissociation (CID) was used to measure the stabilities of boron monoxide cluster ions (BnO+) and energetic and structural information is obtained that indicates that at least, in some cases, oxidation causes structural rearrangement of the clusters. Sequential oxidation of boron cluster ions by CO2 was also studied and the results give further insight into the reaction mechanism and energetics.

Collision-induced dissociation and ab initio studies of boron cluster ions: determination of structures and stabilities [Erratum to document cited in CA109(18):156723t

Collision-induced dissociation and ab initio studies of boron cluster ions: determination of structures and stabilities [Erratum to document cited in CA109(18):156723t

Interaction of boron cluster ions with water: Single collision dynamics and sequential etching

Reactions of mass-selected, cooled, boron cluster ions (B+n, n=1–14) with water have been studied for collision energies from 0.1 to 6.0 eV. Most work was done with D2O, however isotope effects were examined for selected reactant cluster ions. For all size clusters there are exoergic product channels, which in most cases have no activation barriers. Cross sections are generally large, however there are fluctuations with cluster size in total reactivity, collision energy dependences, and in product distributions. For small cluster ions, there is a multitude of product channels. For clusters larger than B+6, the product distributions are dominated by a single channel: Bn−1D++DBO. Under multiple collision conditions, the primary products undergo a remarkable sequence of secondary ‘‘etching’’ reactions. As these occur, boron atoms are continuously replaced by hydrogen, and the intermediate products retain the composition: Bn−mH+m. This highly efficient chemistry appears to continue unchanged as the composition changes from pure boron to mostly hydrogen. Comparison of these results is made with boron cluster ion reactions with O2 and D2, as well as reactions with water of aluminum and silicon cluster ions. Some discussion is given of the thermochemistry for these reactions, and a possible problem with the thermochemical data in the BOD/DBO system is discussed.

Size Dependent Reactions of Boron and Carbon Cluster Ions

ABSTRACTThe results of boron cluster ion reactions with SiH4 and N2O are presented. For N2O reactions, significant size effects were observed in the branching between the BnO+ and BnN+ product channels. Carbon cluster ion reactions with D2 reveal the effect of structural isomers on cluster reactivity.

Dynamics of boron cluster ion reactions with deuterium: Adduct formation and decay

Product cross sections for reaction of size-selected boron cluster ions with deuterium are reported for collision energies ranging from 0.05 to 10 eV. The major reactions are those in which one or two deuterium atoms add to the intact cluster. Other, higher energy channels involve fragmentation of the clusters, with and without addition of deuterium atoms. Cluster size dependent thresholds are observed for many reactions, and we have used these to estimate the cluster–D atom binding energy as a function of cluster size. Metastable adducts of the form BnD+2 are observed for reagent clusters as small as the tetramer. For small clusters, adducts form without activation energy, but starting at B+8 activation barriers are observed. Unimolecular decay rates of the adducts have been estimated, and the binding energy of D2 to various size cluster ions was extracted using RRKM modeling. Comparison is made with related results for boron surfaces and for aluminum cluster ions.

ChemInform Abstract: Collision‐Induced Dissociation and ab intio Studies of Boron Cluster Ions: Determination of Structures and Stabilities

ChemInformVolume 19, Issue 52 Physical Inorganic Chemistry ChemInform Abstract: Collision-Induced Dissociation and ab intio Studies of Boron Cluster Ions: Determination of Structures and Stabilities L. HANLEY, L. HANLEY Dep. Chem., State Univ. N. Y., Stony Brook, NY 11794, USASearch for more papers by this authorJ. L. WHITTEN, J. L. WHITTEN Dep. Chem., State Univ. N. Y., Stony Brook, NY 11794, USASearch for more papers by this authorS. L. ANDERSON, S. L. ANDERSON Dep. Chem., State Univ. N. Y., Stony Brook, NY 11794, USASearch for more papers by this author L. HANLEY, L. HANLEY Dep. Chem., State Univ. N. Y., Stony Brook, NY 11794, USASearch for more papers by this authorJ. L. WHITTEN, J. L. WHITTEN Dep. Chem., State Univ. N. Y., Stony Brook, NY 11794, USASearch for more papers by this authorS. L. ANDERSON, S. L. ANDERSON Dep. Chem., State Univ. N. Y., Stony Brook, NY 11794, USASearch for more papers by this author First published: December 27, 1988 https://doi.org/10.1002/chin.198852002Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume19, Issue52December 27, 1988 RelatedInformation

Collision-induced dissociation and ab initio studies of boron cluster ions: determination of structures and stabilities

Bonding in small boron cluster cations (BZTl3+) is examined by measurement of appearance potentials and fragmentation patterns for collision-induced dissociation (CID) with Xe. Cluster stabilities are generally found to increase with increasing cluster size; however, there are large fluctuations from the overall trend. The lowest energy fragmentation channel for all size cluster ions is loss of a single atom. Clusters smaller than six atoms preferentially lose B', while for the larger clusters the charge remains on the BW1+ fragment. The results are used to estimate cluster ionization potentials and geometries. Comparison of measured stabilities with magic numbers in the cluster ion size distribution and with total CID cross sections shows that neither is a reliable indicator of stability. We also report on ab initio calculations for both neutral and ionic BI4. The results include cluster geometries, ionization potentials, charge distributions, dissociation energies, and bonding character. The results for IPS, geometries, and De)s are compared with experiment.

Oxidation of small boron cluster ions (B+1–13) by oxygen

Absolute cross sections for all ionic products formed in reactions of B+1–13 with oxygen have been measured under single collision conditions, at collision energies from 0.25 to 10 eV. Three main reaction mechanisms appear to be important: oxidative fragmentation, collision induced dissociation, and boron atom abstraction. The dominant oxidation process are exoergic for all cluster sizes, but appear to have bottlenecks or activation barriers for the larger cluster ions. Clusters smaller than B+6 have similar chemistry, then there is a sharp transition in chemistry for clusters larger than B+6 . Correlations are explored between cluster reactivity and cluster stability, and the oxidation chemistry is compared to the similar results found for aluminum cluster ion oxidation.

Production and collision-induced dissociation of small boron cluster ions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProduction and collision-induced dissociation of small boron cluster ionsLuke. Hanley and Scott L. AndersonCite this: J. Phys. Chem. 1987, 91, 20, 5161–5163Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Published inissue 1 September 1987https://doi.org/10.1021/j100304a007RIGHTS & PERMISSIONSArticle Views339Altmetric-Citations86LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (389 KB) Get e-Alerts