Br Ions Research Articles

Corrosion reliability of copper wirebond (CuWB) packages-Impact of voltage and corrosive ions from packaging materials

Reliability of electronic devices used in extreme and harsh conditions such as in automotive applications is often associated with prevention of corrosion at the interfaces of dissimilar interconnect metals and of metal (Al or Cu) bonding pads. Packaging materials, especially molding compounds, contain several ionic components and can uptake certain level of moisture to provide electrolytic conditions to initiate corrosion processes. Probability of occurrence of corrosion in devices with high voltage applications is of special interest as many analog devices operates at higher voltages and with new CuWB packages there is a higher susceptibility of corrosive failures. This paper examines the impact of voltage on the mold compound compatibility with CuWB packages up to 65 V. Bias HAST reliability evaluation of various mold compounds at different voltages will be described. Corrosion of bonding pad (Al) and at the Al-Cu intermetallic compound interface was observed in the presence of certain ions present in mold compounds. Even though current mold compounds are “green”, the allowable amounts of halide ions can far exceed the ppm limit to prevent CuWB corrosive failures. Bromide ions are known to be very corrosive to metals. Br ions are still present in some mold compounds. The impact of the Br ion on CuWB reliability will be described. Additive impact of Br ions in presence of Cl will be examined. Another corrosive component present in many mold compounds, sulfur compounds, also can be corrosive under certain reliability stress conditions. Difference in corrosion behavior of Cu and Pd –Cu wirebonded packages due to sulfur compounds will be presented. Corrosive impact of high levels of Cl on the Al pad corrosion leading thick aluminum oxide growth and reliability failures will be discussed.

Does bromine atom-free radical (Br·) undergo a chemical reaction before dimerization to dibromine (Br2)? An electrochemical investigation

The important question, does bromine atom free radical, Br·, undergo a chemical reaction with a substrate before it dimerizes to dibromine Br2, is investigated through electrochemical oxidation of bromide ion Br−. Cyclic voltammetry and spectrophotometry were used as electro-oxidation and monitoring devices. Simulation of cyclic voltammogram was used to obtain information about the mechanism of electro-oxidation process as well as reaction with substrates. It is shown that the primary electro-oxidation product (PEOP) of Br−, Br· (bromine atom-free radical), reacts with chemicals like chloroform, glycine, cytosine, etc. It can also dimerize, for example in acetonitrile. Reactions of PEOP Br· with substrate chloroform, acetone, DNA components adenine, cytosine, thymine and amino acid glycine were studied and their kinetics are reported here.

Modification of the microstructure and electronic properties of rutile TiO2 thin films with 79 MeV Br ion irradiation

Modifications induced by 79MeV Br ions in rutile titanium dioxide thin films, synthesized by dc magnetron sputtering are presented. Irradiations did not induce any new XRD peak corresponding to any other phase. The area and the width of the XRD peaks were considerably affected by irradiation, and peaks shifted to lower angles. But the samples retained their crystallinity at the highest fluence (1×1013ionscm−2) of irradiation even though the electronic energy loss of 79MeV Br ions far exceeds the reported threshold value for amorphization of rutile TiO2. Fitting of the fluence dependence of the XRD peak area to Poisson equation yielded the radius of ion tracks as 2.4nm. Ion track radius obtained from the simulation based on the thermal spike model matches closely with that obtained from the fluence dependence of the area under XRD peaks. Williamson–Hall analysis of the XRD spectra indicated broadening and shifting of the peaks are a consequence of irradiation induced defect accumulation leading to microstrains, as was also indicated by Raman and UV–Visible absorption study.

Radiation defects studies on silicon bipolar junction transistor irradiated by Br ions and electrons

Bipolar junction transistors are sensitive to both ionization and displacement damage due to charged particles from space radiation. Passivating oxides and the SiO2/Si interface are more sensitive to ionization damage whereas displacement damage may strongly influence the bulk properties of a device. Fast electrons with energies below a few MeV introduces exclusively target ionization while heavy ions at moderate energies (lower than 2MeV/amu) results in displacement damage due to individual Frenkel-pairs generation. Although both kinds of radiation are basically independent an effective correlation was seen in the electronic characteristics of transistors. We report on the effects on current gain and current–voltage characteristics of bipolar junction transistors due to successive irradiation with 20MeV Br ions and 110keV electrons.

Dissociative electron attachment to bromotrifluoromethane

Here we present a study on dissociative electron attachment (DEA) to bromotrifluoromethane, CF3Br, in the energy range from 0 to 10eV. The dominating process observed is the formation of Br− close to 0eV incident electron energy. The fragment ion Br− is also observed through a broad contribution from about 3 to 5eV. In this energy range, F−, FBr− and CF2Br− are also observed, and in the Br− and F− ion yield, a weak contribution is observed close to 8.1eV. For the DEA processes we calculate the thermochemical thresholds using conventional DFT methods, and the results are discussed in context to these, earlier work and the assignment of the underlying resonances.

Structure and properties of electronic and hole centers in CsBr from theoretical calculations

The electronic structure, geometry, diffusion barriers and optical properties of fundamental defects of CsBr are calculated using hybrid functional DFT and TD-DFT methods. The B3LYP functional with a modified exchange contribution has been used in an embedded cluster scheme to model the structure and spectroscopic properties of the self-trapped triplet exciton, interstitial Br atoms and ions, self-trapped holes and Br vacancies. The calculated migration barriers and positions of maxima of optical absorption bands are in good agreement with experiment, justifying the obtained defect geometries. The off-center triplet exciton luminescence energy is also accurately calculated.

Direct Hydrothermal Synthesis of Carbonaceous Silver Nanocables for Electrocatalytic Applications.

This study demonstrates a facile but efficient hydrothermal method for the direct synthesis of both carbonaceous silver (Ag@C core-shell) nanocables and carbonaceous nanotubes under mild conditions (<180 °C). The carbonaceous tubes can be formed by removal of the silver cores via an etching process under temperature control (60-140 °C). The structure and composition are characterized using various advanced microscopic and spectroscopic techniques. The pertinent variables such as temperature, reaction time, and surfactants that can affect the formation and growth of the nanocables and nanotubes are investigated and optimized. It is found that cetyltrimethylammonium bromide plays multiple roles in the formation of Ag@C nanocables and carbonaceous nanotubes including: a shape controller for metallic Ag wires and Ag@C cables, a source of Br(-) ions to form insoluble AgBr and then Ag crystals, an etching agent of silver cores to form carbonaceous tubes, and an inducer to refill silver particles into the carbonaceous tubes to form core-shell structures. The formation mechanism of carbonaceous silver nanostructures depending upon temperature is also discussed. Finally, the electrocatalytic performance of the as-prepared Ag@C nanocables is assessed for the oxidation reduction reaction and found to be very active but much less costly than the commonly used platinum catalysts. The findings should be useful for designing and constructing carbonaceous-metal nanostructures with potential applications in conductive materials, catalysts, and biosensors.

Bromine speciation in hydrous silicate melts at high pressure

Br speciation in hydrous silicate melts at high pressure has been investigated up to 7.6GPa using X-ray absorption spectroscopy (XAS) at the Br K-edge in a Paris–Edinburgh press. Br in silicate melts is surrounded by an average of 6 Na cations, a number slightly increasing with pressure (5.8 to 6.6), with a Br–Na distance increasing from 3.49 to 3.72Å. Two oxygens, either from a water, an –OH molecule or from the tetrahedral silicate network, with an average Br–O distance of 1.80Å, form the closest coordination shell around Br ions. The persistence of an alkali shell around Br, in a structure similar to crystalline NaBr, throughout the pressure range investigated shows that Br can be retained in the melt structure at relatively high pressure and supports the idea of its deep recycling. Finally, our results confirm that Br could be efficiently degassed with water at low pressures and that Br may also have been efficiently degassed along with water during the early stages of an oxidized magma ocean.

Mechanical response to swift ion irradiation-induced nano-tracks in silica

Ion irradiation on dielectric materials produces several processes, such ionization and defect formation followed by a decay governed by thermal processes such as heat diffusion and atomic rearrangement. Finally in the irradiated region the mechanical properties are altered, strain and stress fields appear, a densification takes places and other properties such as the refractive index are affected.In order to simulate the mechanical response of silica to swift ion irradiation we use a methodology based on molecular dynamics (MD) and finite element methods (FEM). We use information from MD to obtain the local densification generated by an incoming swift ion. Finally we calculate the densification in the ion track using FEM. This method provides information on the strain and stress field along the material as a function of ion irradiation fluence.For this work an experimental campaign using Br ions from 5 to 50MeV has been done at CMAM accelerator (Madrid). We measured the refractive index and we observe that for high fluences the refractive index decreases. The effect of the strain field on the density could explain the decrease in the refractive index. We check this hypothesis using our methodology coupling MD and FEM.

Behavior of relative state selective photoionization cross sections of RbBr molecules in the valence region

The photon energy dependence of relative photoionization cross sections in the valence ionization energy region of 5 to 45 eV for 4p and 4s orbitals of Rb and Br ions in RbBr vapors has been investigated. The behavior of state selective cross sections of molecular valence orbitals has been analyzed by comparing the observed 4p to 4s photoelectron intensity branching ratios with atomic state selective photoionization cross sections of Kr, taking into account the mixing between Br 4s(-1) and Rb 4p(-1) molecular states. Using atomic dipole matrix elements to calculate the photoionization intensity of alkali halides has been suggested.

Bifunctional catalysts based on m-phenylene-bridged porphyrin dimer and trimer platforms: synthesis of cyclic carbonates from carbon dioxide and epoxides.

Highly active bifunctional diporphyrin and triporphyrin catalysts were synthesized through Stille coupling reactions. As compared with a porphyrin monomer, both exhibited improved catalytic activities for the reaction of CO2 with epoxides to form cyclic carbonates, because of the multiple catalytic sites which cooperatively activate the epoxide. Catalytic activities were carefully investigated by controlling temperature, reaction time, and catalyst loading, and very high turnover number and turnover frequency were obtained: 220 000 and 46 000 h(-1) , respectively, for the magnesium catalyst, and 310 000 and 40 000 h(-1) , respectively, for the zinc catalyst. Results obtained with a zinc/free-base hybrid diporphyrin catalyst demonstrated that the Br(-) ions on the adjacent porphyrin moiety also function as nucleophiles.

Continuous control of optical gaps in quasi-one-dimensional bromide-bridged platinum complexes by utilizing chemical pressure.

The optical gap in a series of bromo-bridged platinum chain complexes, [Pt(en)2Br](C(n)-Y)2·H2O (en = ethylenediamine; C(n)-Y = dialkyl sulfosuccinate; n = the number of carbon atoms), was controlled by using chemical pressure. From the single-crystal structure, [Pt(en)2Br](C6-Y)2·H2O is in a mixed-valence state at 200 K. In addition, Pt-Pt distances decreased with an increase in n or with a decrease in the temperature. Continuous decreases in the optical gaps upon cooling were observed for n = 5, 7. The smallest gap of 1.20 eV was observed for n = 7 at 50 K. For n = 12, the complex was still in a mixed-valence state at 5 K, although the Pt-Pt distance was quite short. This is probably because of the energetic mismatch between 5dz(2) orbitals of the Pt ions and 4pz orbitals of the Br ions.

Comparison of total dose effects on SiGe heterojunction bipolar transistors induced by different swift heavy ion irradiation

The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV Cl, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current (IB), current gain (β), neutral base recombination (NBR), and Early voltage (VA) were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in IC was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail.

Impact of bias conditions on performance degradation in SiGe HBTs irradiated by 10 MeV Br ion

Effects of bias conditions on 10MeV Br ion irradiation were investigated in NPN SiGe HBTs. Pre- and post-radiation direct current (DC) characteristics, such as current gain, leakage current, Early voltage and neutral base recombination, were studied and used to quantify the dose tolerance to 10MeV Br ion. Experiment results for different bias conditions were compared and discussed in detail. It is found that performance degradations are indeed bias dependent. The BE junction reversed-biased mode suffers the largest degradation and the case with BE junction forward-biased shows the smallest degradation. The underlying physical mechanisms are analyzed and investigated in present work. The injection annealing effect of displacement damage is found to be responsible for the different irradiation response of SiGe HBTs under three bias conditions.

국내산 갯벌천일염과 외국산 소금의 미네랄, 중금속 및 phthalate 함량 평가

The purpose of this study was to evaluated a phthalate, heavy metal contents and physicochemical quality properties in korean mudflat solar salt and foreign salts. DEHP in mudflat solar salt (MSS) was detected a low level (9.00~669.89 ppb), but it was shown a high level excess to 1.5 ppm criteria in the foreign solar salt (FSS) 5 type (3,440.64, 3,266.56, 2,189.65, 4,010.69, 4,554.20 ppb) and foreign large solar salt (FLSS) 1 type (1,983.27 ppb). Also, DEHP in FSS 2 type (930.15, 1,310.07 ppb) and FLSS 1 type (924.92 ppb) was detected a high level not excess to criteria. No detected DMP, DEP, DIBP, DBP, DAP, BBP, DCHP and DEHA contents in MSS and foreign salt (FS). Na ion was shown a significantly higher level (p&lt;0.05) in FS (407,345.87~426,612.14 ppm) than in MSS (363,633.98 ppm), but it was shown a high level in Mg (p&lt;0.01), K (p&lt;0.05), Ca ion (p&lt;0.05) of FSS compared to foreign refined salt (FRS). Cl ion (532,727.07 ppm) of MSS was the most low level (p&lt;0.001) compared to FS, but it was shown a high level (p&lt;0.001) in Br ion (625.07 ppm). SO4 ion was not shown a significant difference in DS and FS. It was display a high level in Mn of MSS, and Al, Fe of FLSS. Heavy metal contents (As, Cd, Pb and Hg) in MSS and FS was not significant difference, it was safety level as edible salt.

Formation potentials of bromate and brominated disinfection by-products in bromide-containing water by ozonation.

The ozonation involved in drinking water treatment raises issues of water quality security when the raw water contains bromide (Br(-)). Br(-) ions may be converted to bromate (BrO3 (-)) during ozonation and some brominated disinfection by-products (Br-DBPs) in the following chlorination. In this study, the effects of ozone (O3) dosage, contact time, pH, and Br(-) and ammonia (NH3-N) concentrations on the formation of BrO3 (-) and Br-DBPs have been investigated. The results show that decreasing the initial Br(-) concentration is an effective means of controlling the formation of BrO3 (-). When the concentration of Br(-) was lower than 100 μg/L, by keeping the ratio of O3 dosage to dissolved organic carbon (DOC) concentration at less than 1, BrO3 (-) production was effectively suppressed. The concentration of BrO3 (-) steadily increased with increasing O3 dosage at high Br(-) concentration (>900 μg/L). Additionally, a longer ozonation time increased the concentrations of BrO3 (-) and total organic bromine (TOBr), while it had less impact on the formation potentials of brominated trihalomethanes (Br-THMFP) and haloacetic acids (Br-HAAFP). Higher pH value and the presence of ammonia may lead to an increase in the formation potential of BrO3 (-) and Br-DBPs.

In situ study of oxidative etching of palladium nanocrystals by liquid cell electron microscopy.

Oxidative etching has widely prevailed in the synthesis of a crystal and played a critical role in determining the final growth behavior. In this Letter, we report an in situ microscopic study on the oxidative etching of palladium cubic nanocrystals by liquid cell scanning transmission electron microscopy. The etching was realized with oxidative radiation reactants from electron-water interaction in the presence of Br(-) ions. Dissolution dynamics of monodispersed and aggregated nanocrystals were both investigated and compared. Analyses on the dissolution kinetics of nanocrystals and the diffusion kinetics of the dissolved agents were carried out based on the scanning transmission electron microscopy characterizations. The results presented here pave a way toward the quantitative understanding of the oxidative etching reaction and its application in the functionally orientated fabrication of nanocrystals with certain sizes, structures, and morphologies.

Evaluation of soil salinization in a Mediterranean site (Agoulinitsa district—West Greece)

Soil salinization is an environmental problem having significant impacts on the soil–water–plant system. This problem is more frequent in coastal areas due to seawater intrusion into the land. Assessing the soil salinization is a critical issue for the agricultural areas situated in the Mediterranean basin. This paper examines the deterioration of soil quality in the cultivated land of a Mediterranean site (Agoulinitsa district—West Greece). Soil samples were collected in both pre-irrigation and post-irrigation seasons. Electrical conductivity (EC), pH and the ions Br−, Ca2+, Cl−, F−, K+, Li+, Mg2+, Na+, NH4+, NO2−, NO3−, PO43− and SO42− were determined by the 1:2 (soil/water ratio on weight basis) method. The salts which were present in both seasons in the soils of the area studied are KCl, MgCl2, NaCl, CaSO4 and K2SO4. The wide spatiotemporal variation of EC in the cultivated land in both seasons demonstrates that soil salinity is controlled mainly by seawater intrusion and anthropogenic factors such as the application of salt-rich water which is directly pumped from the drainage ditches. Seawater intrusion provides the affected soil with elevated contents of Ca2+, Cl−, K+, Mg2+, Na+ and SO42−. Classification of the soils by using criteria given by the literature is discussed. Practices to prevent, or at least ameliorate, salinization in the cultivated land of Agoulinitsa district are proposed.

Electronic stopping powers for heavy ions in SiC and SiO2

Accurate information on electronic stopping power is fundamental for broad advances in materials science, electronic industry, space exploration, and sustainable energy technologies. In the case of slow heavy ions in light targets, current codes and models provide significantly inconsistent predictions, among which the Stopping and Range of Ions in Matter (SRIM) code is the most commonly used one. Experimental evidence, however, has demonstrated considerable errors in the predicted ion and damage profiles based on SRIM stopping powers. In this work, electronic stopping powers for Cl, Br, I, and Au ions are experimentally determined in two important functional materials, SiC and SiO2, based on a single ion technique, and new electronic stopping power values are derived over the energy regime from 0 to 15 MeV, where large deviations from the SRIM predictions are observed. As an experimental validation, Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) are utilized to measure the depth profiles of implanted Au ions in SiC for energies from 700 keV to 15 MeV. The measured ion distributions by both RBS and SIMS are considerably deeper than the SRIM predictions, but agree well with predictions based on our derived stopping powers.

Investigation on the Response of TaO$_{\rm x}$-based Resistive Random-Access Memories to Heavy-Ion Irradiation

Impact of heavy-ion irradiation on the TaOx-based resistive random-access memory (RRAM) is investigated in this work. After Br ion irradiation, the set voltage of TaOx-based RRAM shows slight change, and negative shift of the forming voltage is observed. For the resistance change of TaOx-based RRAM devices induced by irradiation, the resistance of the low resistance state (LRS) illustrates acceptable change, while the resistance of the high resistance state (HRS) is quite sensitive to heavy ion irradation. Some irradiated devices even change from the HRS into the LRS, which results in disappeared memory window and may be attributed to the displacement damage in the dielectric layer. These results indicate that TaOx-based RRAM devices need to be carefully designed for future space applications.