Influence of Cu electroplating solutions on boron carbon nitride (BCN) film

Cu electroplating is required for the fabrication of Cu/low-k interconnections. The permeation of a plating solution into low-k films during Cu electroplating is a serious challenge for 45-nm nodes and more complex devices. We investigated the influence of Cu electroplating solutions on boron carbon nitride (BCN) as a low-k film. After dipping it into a Cu electroplating solution that contained additives, the BCN film's hydrophilic surface changed to a hydrophobic surface, and the incorporation of water into the BCN film was suppressed by surfactant adsorption. Sulfuric residue was detected on the BCN sample by thermal desorption spectroscopy after treatment in the Cu electroplating solution with additives; however, it was found through electrical measurements that this solution did not affect the leakage current or the dielectric constant of the BCN film. We successfully fabricated an electroplating Cu layer on a BCN film with good adhesion, and we believe that this BCN film is a sufficiently useful material for Cu/BCN integration in LSI.     

Characterization of boron carbon nitride film modified by excimer laser annealing

Boron carbon nitride (BCN) shows promise as a field emitter material because of its mechanical hardness, chemical inertness, and low electron affinity. This study investigated the modification of a BCN film with an amorphous area using KrF excimer laser (wavelength: 248 nm, photon energy: 5.0 eV) annealing without substrate heating. This achieved significant variation in characteristics, such as an increase in bandgap energy and decrease in electron affinity. Laser annealing reduced electron affinity from 0.7 to 0.3 eV. The results indicate that the modification of the BCN film by KrF excimer laser annealing achieves characteristics similar to hexagonal BN (h-BN) film without losing the desirable properties of the BCN film, such as physical stability.     

Development of superhard materials,sintered diamond and cubic boron nitride

Abstract

Recent advances on the preparation technique of sintered diamond and cubic boron nitride containing small amount of sintering additives having superior thermal and mechanical properties is reviewed. Sintered diamond of lower metallic content (1–5 vol%) shows high hardness (100–150 GPa) and high electrical resistivity (10⁸ ohm-cm) at room temperature. Reaction sintered cubic boron nitride contained 1–3 mole % of magnesium boron nitride shows high thermal conductivity. (7 watt/cm K at RT)     

A first-principle study of the structural, elastic, lattice dynamical and thermodynamic properties of PrX (X=P, As)

The structural, phase transition, elastic, lattice dynamic and thermodynamic properties of rare-earth compounds PrP and PrAs with NaCl (B1), CsCl (B2), ZB (B3), WC (B_h) and CuAu (L1₀) structures are investigated using the first principles calculations within the generalized gradient approximation (GGA). For the total-energy calculation, we have used the projected augmented plane-wave (PAW) implementation of the Vienna Ab-initio Simulation Package (VASP). Specifically, some basic physical parameters, e.g. lattice constants, bulk modulus, elastic constants, shear modulus, Young's modulus and Poison's ratio, are predicted. The obtained equilibrium structure parameters are in excellent agreement with the experimental and theoretical data. The temperature and pressure variations of the volume, bulk modulus, thermal expansion coefficient, heat capacity and Debye temperature are calculated in wide pressure and temperature ranges. The phonon dispersion curves and corresponding one-phonon density of states (DOS) for both compounds are also computed in the NaCl (B1) structure.     

Electronic transport properties of an (8,0) carbon/boron nitride nanotube heterojunction

The structure of a heterojunction made up of an (8, 0) carbon nanotube and an (8, 0) boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geometry, the model of the heterojunction is established. Its transport properties are investigated by combining the nonequilibrium Green's function with density functional theory. Results show that both the lowest unoccupied molecular orbital and the highest occupied molecular orbital mainly locate on the carbon nanotube section. In the current--voltage characteristic of the heterojunction, a rectification feature is revealed.     

六方氮化硼单层中一种(CN)3VB缺陷的第一性原理计算

二维六方氮化硼(hBN)的点缺陷最近被发现可以实现室温下的单光子发射,而成为近年的研究热点.尽管其具有重要的基础和应用研究意义,hBN中发光缺陷的原子结构起源仍然存在争议.本文采用基于密度泛函理论的第一性原理计算,研究hBN单层中一种B空位附近3个N原子被C替代的缺陷(CN)3VB.在hBN的B空位处,3个N原子各自带...     

Adsorption and thermodynamic studies of Cu(II) and Zn(II) on organofunctionalized-kaolinite

Kaolinite-bearing clay samples from Perus, São Paulo state, Brazil, were used for chemical modification process with dimethyl sulfoxide and organofunctionalized with the silyating agent (RO)₃Si(CH₂)₃NH(CH₂)₂NH₂ in the present study. The resulting material and natural kaolinite were subjected adsorpion process with Cu(II) and Zn(II) from aqueous solution at pH 6.0 and controlated temperature of 298 K. The Langmuir adsorption isotherm model has been applied to fit the experimental data. The results showed that the chemical modification process increases the basal spacing of the natural kaolinite from 0.711 to 0.955 nm. The energetic effects caused by Cu(II) and Zn(II) interactions were determined through calorimetric titration at the solid–liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.     

Uniform upper bounds (and thermodynamic limit) for the correlation functions of symmetric coulomb-type systems

Uniform upper bounds are proven for the correlation functions in the strictly charge-neutral canonical and grand canonical ensembles for charge-symmetric two-component systems. For the grand canonical ensemble the increase of the correlation functions along the thermodynamic-limit sequence is shown as well, implying the existence of the states. The particles have bounded pair interactions of positive type. Both classical and quantum systems with Boltzmann statistics are considered. Coulomb systems with regularized interactions are included as a special case.     

Diamond and cubic boron nitride under high pressure: Raman scattering,equation of state and high pressure scale

Abstract

The development of the diamond-anvil cell has stimulated Raman-scattering investigation of vibrational modes in covalent crystals. The linear pressure coefficient reported for diamond by Hanfland et at' (2.90 ± 0.05 cm-¹/GPa) agrees to within mutual experimental error with the result of Boppard et aL² (2.87±0.01 cm-¹/GPa). As to cubic boron nitride, the only work by Sanjurjo ef aL3 reports 3.45 ± 0.07 cm-¹/GPa for LO- and 3.39 ± 0.08 cm-¹/GPa for TO- modes. Since no compressibility data are availablel^1?3, the mode Griineisen parameter γ = ‐ δ In γ/δ is defined as y = K/Y·dv/aP and depends on the bulk modulus K and the calibration of the ruby scale. The above papers report y= 0.96 and y=0.95±O.O3fordiamondand γ_Lo=1.21,γTo=1.51 forBN.     

A contribution to the equation of state of fluids at low temperatures based on thermodynamic Green's functions

In quantum statistical mechanics, the Green's function formalism provides an expression for the density of a fluid as a four-dimensional momentum-energy integral over the spectral function. This function can be expressed in terms of the complex self-energy of the single-particle excited states. By using the ladder diagram approximation, in a low activity limit at which Fermi-Dirac and Bose-Einstein distributions can be approximated by a Boltzmann distribution, the self-energy has been expressed in terms of the two-body scattering amplitude. Density and pressure can then be expressed in terms of the activity, the temperature, and the two-body scattering phase shifts. A complete numerical evaluation of these results has been made for the case of argon at 100K, represented by a hard-sphere plus square-well potential: results are presented for the complex self-energy, the density, and the pressure as a function of activity. The resulting equation of state is compared to experimental results represented by the Beattie-Bridgeman equation and good agreement is found for the gaseous part of the 100K isotherm. Furthermore, two simple analytic equations of state are derived from these expressions with additional (low-density) approximations, which resemble closely some of the equations obtained from the lattice gas theories.Work supported (in part) by the Defence Research Board of Canada, Grant No. DRB 9510-30, and by the Research Council of Texas A & M University.     

Elastic and thermodynamic properties of AVO3 (A=Sr, Pb) perovskites

We have investigated the elastic and thermodynamic properties for the perovskite type metavanadate SrVO₃ and the multiferroic PbVO₃, probably for the first time by the means of a Modified Rigid Ion Model (MRIM). We present the elastic constants (C_11,C_12,C₄₄) and other elastic properties like Bulk modulus (B), Young′s modulus (E), shear modulus (G), Poisson′s ratio (σ) and wave velocity (υ_l, υ_s, υ_m). Besides we have reported the thermodynamic properties molecular force constant (f), Reststrahlen frequency (ν), cohesive energy (?), Debye temperature (θ_D) and Gruneisen parameter (γ). We have also computed the variation of heat capacity (C_P) and there by volume thermal expansion coefficient (α) in a wide temperature range. We found that the computed properties reproduce well with the available data in literature. To our knowledge some of the properties are reported for the first time.     

Ab initio thermodynamic characteristics of the formation of oxygen vacancies,and boron,carbon, and nitrogen impurity centers in anatase

Using the ab initio projector augmented wave (PAW) method, calculations are performed for the electronic energy-band structure of titanium dioxide having the structure of anatase doped with boron, nitrogen, and carbon. Thermodynamic characteristics are determined for the formation of impurity centers, such as the preference energy for the interstitial position, the energy of impurity oxidation, and the energy of oxygen vacancy formation. It is shown that under the conditions of thermodynamic equilibrium the interstitial position of boron atoms is stable, whereas carbon atoms, depending on the oxygen pressure, can occupy both interstitial positions and substitutional positions of oxygen atoms, and nitrogen atoms replace oxygen atoms. It is shown that the presence of oxygen vacancies promotes the thermodynamic stability of carbon and nitrogen atoms. The obtained densities of electronic states correspond to ESR spectroscopy data, which indicates the presence of spin-polarized electrons in the states of the oxygen vacancy.     

The structural, elastic and thermodynamic properties of thorium tetraboride

The structural, elastic and thermodynamic properties of thorium tetraboride (ThB₄) have been investigated by using first-principles plane-wave pseudopotential density functional theory with generalized gradient approximation. The behaviors of structural parameters under 0-70 GPa hydrostatic pressure are studied by means of Broyden, Fletcher, Goldfarb, and Shanno (BFGS) geometry optimization scheme. By using the stress-strain method, single crystal elastic constants are calculated to test the mechanical stability of the crystal structure and to determine mechanical properties such as bulk modulus at each pressure. However, in order to study the thermodynamic properties of ThB₄, the quasi-harmonic Debye model is used. Then, the dependencies of bulk modulus, heat capacities, thermal expansions, Grüneisen parameters and Debye temperatures on the temperature and pressure are obtained in the whole pressure range 0-70 GPa and temperature range 0-1500 K.     

Ab initio electronic, dynamic, and thermodynamic properties of isotopic lithium hydrides (LiH, LiD, LiT, LiH, LiD, and LiT)

The structural, dielectric, lattice-dynamical, and thermodynamical properties of isotopic lithium hydrides (⁶LiH, ⁶LiD, ⁶LiT, ⁷LiH, ⁷LiD, and ⁷LiT) were investigated within density-functional theory. The atomic structure was fully relaxed and the structural parameters were found to differ by less than 2% from the experimental data. The associated electronic band structure and density of states were also presented. A linear-response approach to the density-functional perturbation theory was employed to work out the Born effective charges, dielectric tensors and phonon frequencies, and thermodynamic properties. The compounds with the heavier Li isotope or H isotope have the lower phonon frequencies; ⁶LiT is more stable than ⁷LiT, ⁶LiD, ⁷LiD, ⁶LiH, and ⁷LiH in the temperature range 0-2700 K. These properties of LiT were predicted for the first time. The results were discussed in terms of the isotope effects on phonon dispersion curves and thermodynamic properties.     

Thermodynamic properties and phase diagram of the graphite-diamond-liquid carbon system

Abstract

We review work performed on a three-phase theoretical carbon equation of state. The algorithm has been used, with good success, in a chemical equilibrium code of mixtures (of solids, liquids, and gasses), in which the gas phase is modeled by a statistical mechanical theory of mixtures. We use simple Grüneisen models for the solid phases and compute the corresponding liquid phases with a “scaling” theory. A modified Lindemann model is used in the scaling theory to predict melting properties. The liquid carbon consists of a mixture of expanded graphitic and diamond-like forms. Terms that describe the electronic energy change of the liquid have been estimated with the INFERNO code. Both experimental and theoretical work has been used to determine the best equation of state parameters. The resulting model yields a phase diagram consistent with all known mutually consistent data. Significant uncertainties still exist in the melting data.     

Theoretical study of the transition metal ring functionalized tips of open-ended (5,5) boron nitride nanotube (BNNT)

The nanotube with open edges is an excellent candidate for designing efficient tip for atomistic scanning probes or field emission display (FED) devices. In the present work, we have studied the functionalization of an open-ended boron nitride nanotube (BNNT) with a series of transition metal rings and the effects on the properties of open-ended BNNT through density functional theory (DFT) calculations. The results show that the TM-BNNT complexes are energetically favorable. Moreover, it is found that the functionalization (a) significantly decreases the band gap of BNNT to different degrees, which might effectively modify the electronic properties of the open-ended BNNT; and (b) efficiently lowers the work function, which might improve the field emission properties. Our results might be helpful not only to design specific BNNT-based tips but also to further discuss the chemical vapor deposition (CVD) growth of BNNT on nanoparticles.     

Peculiarities of spontaneous crystallization of cubic boron nitride single crystal powders in the Li-B-N (H,Be) system

Abstract

We have investigated the effect of beryllium additions on the kinetics of conversion of hexagonal graphite-like BN to cubic BN (hBN → cBN) as well as on the linear rate of cBN crystal growth in a Li-B-N (H, Be) system. Experiments were performed in the temperature range 1940-2080K at a pressure of 4.3GPa. With the addition of 0.25 and 0.50wt.% beryllium the activation energy of the cBN formation process is found to be 45.8 and 42.0kJ/mol, respectively. The resulting crystals showed p-type conductivity. The activation energy of the impurity carriers for the samples with 0.25 and 0.50 wt.% beryllium additions equalled 0.22 and 0.17eV, respectively.     

Equations of state for metals (Al, Fe, Cu, Pb), polyethylene, carbon, and boron nitride as applied to problems of dynamical compression

Metals (Al, Fe, Cu, Pb), polyethylene, and other plastic materials with a density of about 1 g/cm³ are commonly used as liners and screens in solving dynamic-compression problems that involve phase transitions. In this paper, the equations of state are presented in the form of formulas, graphs, and tables for the pressurep and energyE as functions of temperatureT and density ρ. These equations have a meaningful theoretical form and are based on the measured initial sound velocityc ₀, densityρ ₀, Gruneisen parameter Γ, heat capacityc _p, sublimation energyU _evp, and the known pressure dependence of the compression modulus ϱK/ϱp. These equations of state are in satisfactory agreement with available experimental data on shock compression. According to the same scheme, the equations of state are derived for carbon and boron nitride. However, in this case, the situation turned out to be much more complicated due to the existence of phase transitions from the hexagonal form into wurtzite and cubic forms. In deriving the equation of state, the equilibrium curve between the graphite-like and diamond phases on the phase diagram was additionally used. As a result of realization of the aforementioned scheme, the equations of state obtained (i.e., formulas, graphs, and tables) are in satisfactory agreement with experimental data. Translated from Preprint of the P. N. Lebedev Physical Institute No. 28 (1996).     

Theoretical study on Si-doped hexagonal boron nitride (h-BN) sheet: Electronic,magnetic properties,and reactivity

The properties and reactivity of Si-doped hexagonal boron nitride (h-BN) sheets were studied using density functional theory (DFT) methods. We find that Si impurity is more likely to substitute the boron site (Si_B) due to the low formation energy. Si-doping severely deforms h-BN sheet, resulting in the local curvature changes of h-BN sheet. Moreover, Si-doping introduces two spin localized states within the band gap of h-BN sheet, thus rendering the two doped systems exhibit acceptor properties. The band gap of h  -BN sheet is reduced from ∼4.70 eV$\sim 4.70\text{eV}$ to 1.24 (for Si_B) and 0.84 eV (for Si_N), respectively. In addition, Si-doped one exhibits higher activity than pristine one, endowing them wider application potential.