Spectrophotometric determination of traces of boron in silicon by means of solvent extraction

A spectrophotometric method for the determination of boron in silicon based on the extraction of the methylene blue-fluoroborate complex has been improved. Some important points, such as the dissolution of silicon with hydrofluoric acid and hydrogen peroxide, the effect of various anions on the blank absorbance and the best working conditions for forming and extracting the complex, have been studied. The method is applied to the determination of boron in silicon containing at least 1 p.p.m. of boron, with a relative standard deviation of ±5%.     

Potentiometric determination of boron in silicon with an ion-selective electrode

A potentiometric method is proposed for the determination or boron in silicon, based on dissolution of silicon by treatment with hydrofluoric acid and ammonium fluoride in the presence of hydrogen peroxide, and conversion of boron to fluoroborate ion. The fluoroborate activity is measured with the Orion fluoroborate-selective electrode. Some important points, such as the effect of various interfering ions and the hydrolysis of fluoroborate ion, are described in detail. The method is applied to the determination of boron in silicon containing at least 10 p.p.m. of boron, with a relative standard deviation of ±4%.     

Effect of boron on the surface tension of molten silicon and its temperature coefficient

The influence of boron concentration (C(B)/mass%) on the surface tension of molten silicon has been investigated with the sessile drop method under oxygen partial pressure P(O(2))=1.62x10(-25)-2.63x10(-22) MPa, and the results can be summarized as follows. The surface tension increases with C(B) in the range below 2.09 mass%, and the maximum increase rate of the surface tension is about 30 mN m(-1)(mass% C(B))(-1). The temperature coefficient of the surface tension, ( partial differential sigma/ partial differential T)C(B), was found to increase with the boron concentration in molten silicon. At the interface between molten silicon and the BN substrate, a discontinuous Si(3)N(4) layer was reckoned to form and the layer might prevent BN from dissolving into the molten silicon. Since dissolved boron from the BN substrate into the molten silicon is below 0.054 mass% and the associated increase in surface tension is below 1.5 mN m(-1), the contamination from the BN substrate on the surface tension can be ignored. The relation between the surface tension and C(B) indicates negative adsorption of boron and can be well described by combining the Gibbs adsorption isotherm with the Langmuir isotherm.     

Zur borbestimmung in silizium und germanium durch aktivierung mit protonen und deuteronen

The determination of boron via the nuclear reaction ¹¹B(p,n)¹¹C was studied in detail; the nitrogen reaction ¹⁴N(p,a)¹¹C interferes. Nitrogen also interferes deuteron activation via the nuclear reactions 10B(d,n)¹¹C and ¹¹B(d,2n)¹¹C, this interference must be attributed to the nuclear reaction ¹⁴(d,αn)¹¹C. Both interferences were investigated quantitatively. The conditions for the accurate determination of boron and for a simultaneous determination of boron and nitrogen by proton activation were established. An analytical method with chemical separation of the radioisotope ¹¹C was developed for silicon and germanium.     

The morphology of ceramic phases in BxC-SiC-Si infiltrated composites

The present communication is concerned with the effect of the carbon source on the morphology of reaction bonded boron carbide (B₄C). Molten silicon reacts strongly and rapidly with free carbon to form large, faceted, regular polygon-shaped SiC particles, usually embedded in residual silicon pools. In the absence of free carbon, the formation of SiC relies on carbon that originates from within the boron carbide particles. Examination of the reaction bonded boron carbide revealed a core-rim microstructure consisting of boron carbide particles surrounded by secondary boron carbide containing some dissolved silicon. This microstructure is generated as the outcome of a dissolution-precipitation process. In the course of the infiltration process molten Si dissolves some boron carbide until its saturation with B and C. Subsequently, precipitation of secondary boron carbide enriched with boron and silicon takes place. In parallel, elongated, strongly twinned, faceted SiC particles are generated by rapid growth along preferred crystallographic directions. This sequence of events is supported by X-ray diffraction and microcompositional analysis and well accounted for by the thermodynamic analysis of the ternary B-C-Si system.     

Consolidation by Spark Plasma Sintering of a Ceramic Material Based on Silicon Carbide with Good Physicomechanical Properties,Mechanochemically Activated with Boron

Industrial silicon carbide powder was consolidated with boron by the spark-plasma-sintering (SPS) method. It was shown that a preliminary mechanical activation is a promising method for introduction of high concentrations of boron into silicon carbide. The influence exerted by the boron concentration on the sintering and properties of the material based on silicon carbide was examined. A ceramic based on silicon carbide with 10 wt % amorphous boron was obtained with density of 3.12 g cm^–3, hardness of 31.9 GPa, and crack-resistance coefficient of 5.7 MPa m^1/2. The ceramic is promising as a construction ceramic for nuclear reactors and gas-turbine engines.     

Preparation of a mesoporous silicon boron nitride via a non-aqueous sol-gel route

A silicon boron imide based gel Si3B(NH)x(NH2)y(NMe2)z was prepared via catalytic ammonolysis of tris[tris(dimethylamino)silylamino]boron B[HNSi[N(CH3)2]3]3; pyrolysis of the gel under ammonia at 1,000 degrees C gives a mesoporous silicon boron nitride with high surface area and narrow pore size distribution.     

Isomorphous substitution of silicon by boron in layered sodium silicate hydrates

To investigate the influence of boron on the crystallization process and the substitution of silicon by boron in silicate layers, layered sodium silicate hydrates (Na-SH) have been synthesized hydrothermally from a boron-containing mixture. XRD measurements confirm the high crystallinity of the synthesized Na-SH.¹¹B MAS NMR measurements indicate that boron is incorporated luto the silicate layers instead of silicon atoms.     

X射线荧光光谱法快速测定FeSiB非晶合金薄带中硅、硼、铁

提出了以自制的标准样品,采用单点法绘制校准曲线,利用X射线荧光光谱仪测定FeSiB非晶薄带样品中硅、硼和铁的含量。对于4个FeSiB非晶合金薄带样品中硅、硼和铁进行了10次测定,其分析结果的相对标准偏差分别为0.4%~0.5%、1.3%~4.2%和0.2%~0.4%。方法的分析结果与火花源原子发射光谱法、化学重量法和电感耦合等离子体原子发射光谱(ICP-AES)法的测定值吻合较好。方法快速、简便,薄带样品无需制样,适用于FeSiB非晶合金薄带的快速成分分析。     

Spectrophotometric determination of trace and ultratrace levels of boron in silicon and chlorosilane samples

Summary Spectrophotometric methods for the determination of boron in the low g/g and ng/g range in high-purity silicon and dichloro- and trichlorosilanes were investigated in detail. The procedures established involve dissolution of silicon samples and the hydrolyzed products of chlorosilane samples in hydrofluoric acid-containing reagents followed by evaporation of the silicon matrix as H₂SiF₆. The boron retained in the treated sample solution was then determined by a spectrophotometric method using carminic acid as a chromatic reagent. Special effort has been paid to the control of the analytical blank and reproducible determination of boron. The results indicate that addition of mannitol and proper control of the evaporation process are effective in preventing volatilization of boron during the evaporation of silicon matrix and can thus attain high recovery of boron and reproducible analysis. Through meticulous control of the analytical blank and experimental conditions, the limit of detection for boron determination with the established method can be as low as ng/g levels. Application of the methods to the determination of boron in various stages of purification of silicon and trichlorosilane as well as in borophosphosilicate film was conducted.     

Density Functional Theory Investigations on M + CO2 towards MO + CO (M =B, Al, Si)

The catalytic activation of carbon dioxide by metals and non-metals is one of the attractive scientific challenges in scientific community. In this work, the conversion mechanisms of CO2 to CO by B, Al and Si were elucidated extensively at the B3LYP/6-311++G(d,p) basis set level. Our theoretical mode testifies that the reaction mechanisms of these three systems are significantly different from each other, and both boron and silicon have good performance in the conversion of CO2 to CO.     

X射线荧光光谱法快速测定FeSiB非晶薄带中Si,B,Fe的含量合金薄带中硅硼铁

提出了以自制的标准样品,采用单点法绘制校准曲线,利用X射线荧光光谱仪测定FeSiB非晶薄带样品中硅、硼和铁的含量。对于4个FeSiB非晶合金薄带样品中硅、硼和铁进行了10次测定,其分析结果的相对标准偏差分别为0.4~0.5%,1.3~4.2%和0.2~0.4%。本方法的分析结果与火花源原子发射光谱法、化学重量法和ICP-AES的测定值吻合较好。本方法快速、简便,薄带样品无需制样,适用于FeSiB非晶合金薄带的快速成分分析。     

Separation et dosage de traces de bore dans le silicium : Nouvelle méthode de séparation et de dosage de traces de bore. application au dosage du bore dans le silicium

A new method is described for the separation and determination of traces of boron by extraction of methylene blue fluoroborate by dichlorethane The method has been applied to the determination of traces of boron in silicon and silica     

Preparation of polyboronphenylsiloxanes by mechanochemical activation

Linear polyboronphenylsiloxanes containing fluorine atom at silicon and acetylacetonate group at boron have been synthesized by mechanochemical activation. Mechanochemical activation of polyphenylsilsesquioxane and boron difluoride acetylacetonate taken in molar ratio 1 : 1 was shown to lead to the formation of polyboronphenylsiloxane with the given Si/B ratio. The products are characterized by gel chromatography, IR, NMR spectroscopy, elemental analysis, and X-ray phase analysis. The increase of the starting ratio Si/B enhances side processes and formation of polydisperse products with the Si/B ratio different from the desired one. The mechanism of the reaction is suggested.     

Development of an on-line isotope dilution laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for determination of boron in silicon wafers

A method has been developed based on an on-line isotope dilution technique couple with laser ablation/inductively coupled plasma mass spectrometry (LA-ICP-MS), for the determination of boron in p-type silicon wafers. The laser-ablated sample aerosol was mixed on-line with an enriched boron aerosol supplied continuously using a conventional nebulization system. Upon mixing the two aerosol streams, the isotope ratio of boron changed rapidly and was then recorded by the ICP-MS system for subsequent quantification based on the isotope dilution principle. As an on-line solid analysis method, this system accurately quantifies boron concentrations in silicon wafers without the need for an internal or external solid reference standard material. Using this on-line isotope dilution technique, the limit of detection for boron in silicon wafers is 2.8 × 10¹⁵ atoms cm⁻³. The analytical results obtained using this on-line methodology agree well with those obtained using wet chemical digestion methods for the analysis of p-type silicon wafers containing boron concentrations ranging from 1.0 × 10¹⁶ to 9.6 × 10¹⁸ atoms cm⁻³.     

Spectrophotometric Determination of Traces of Boron in High Purity Silicon

Abstract

A reddish brown complex is formed between boron and curcumin in concentrated sulphuric acid and glacial acetic acid mixture (1:1). the coloured complex is highly selective and stable for about 3 hours and has the maximum absorbance at 545 nm. the sensitivity of the method is extremely high and the detection limit is 3 parts per billion based on 0.004 absorbance value. the interference of some of the important cations and anions relevant to silicon were studied and it is found that 100 fold excess of most of these cations and anions do not interfere in the determination of boron. the method is successfully employed for the determination of boron in silicon used in semiconductor devices. the results have been verified by standard addition method.     

Determination of boron in the thin surface layer of a silicon wafer by instrumental charged particle activation analysis

Instrumental charged particle activation analysis (CPAA) for determining boron in a thin surface layer of silicon was developed. The nuclear reaction and incident energy were selected in order to minimize any interference from surface or bulk impurities. Thin boron film was used as a standard sample and its boron content was determined by neutron induced prompt -ray analysis. As a result, we were able to determine¹¹B and¹⁰B at 10¹⁵ atoms/cm² with an accuracy of better than 3% by 4 MeV proton and 7 MeV -bombardment, respectively. Each boron isotope could be determined down to 10¹³ atoms/cm². Our CPAA was applied to determine boron in a boron implanted silicon wafer of a SIMS standard sample.     

Preparation of SiBN films deposited by MOCVD

SiBN films were prepared by the MOCVD method using triethylsilane and triethylboron as source materials. The SiBN films were a mixture of boron nitride and silicon nitride determined by IR spectra. The relationship between the ratio of mixture and the preparation condition is clarified. The ratio of silicon nitride to boron nitride in the films was proportional to the ratio of triethylsilane to triethylboron under a large excess of ammonia flow condition. The reaction temperature also influenced the ratio of boron nitride and silicon nitride in the films. The deposition rate of the film increased up to 800°C with a maximum at 1000°C, and decreased up to 1300°C with small value. The crystallinity of SiBN films was very poor because the crystal growth was obstructed.     

Quantitative investigation of boron incorporation in polycrystalline CVD diamond films by SIMS

Polycrystalline diamond films have been produced on pre-treated silicon substrate by CVD hot filament method, with B(C₂H₅)₃ added to the gas phase. However, under identical surface conditions, boron incorporation is not homogeneous. In {111} growth sectors, the boron concentration is found to be about 5 times higher than in {100} growth sectors. Moreover, a marked increase in contaminating elements such as aluminium and sodium in regions with higher boron concentrations is detected. Under SIMS fine focus conditions it can be shown that the interface between these two different facet regions is smaller than 0.5 μm. With 3D-depth profile images it can also be shown that the carbon distribution in the diamond layer is not totally homogeneous.     

Quantitative investigation of boron incorporation in polycrystalline CVD diamond films by SIMS

Polycrystalline diamond films have been produced on pre-treated silicon substrate by CVD hot filament method, with B(C₂H₅)₃ added to the gas phase. However, under identical surface conditions, boron incorporation is not homogeneous. In {111} growth sectors, the boron concentration is found to be about 5 times higher than in {100} growth sectors. Moreover, a marked increase in contaminating elements such as aluminium and sodium in regions with higher boron concentrations is detected. Under SIMS fine focus conditions it can be shown that the interface between these two different facet regions is smaller than 0.5?μm. With 3D-depth profile images it can also be shown that the carbon distribution in the diamond layer is not totally homogeneous.