Quantitative determination of oxygen in silicon by combination of FTIR-spectroscopy,inert gas fusion analysis and secondary ion mass spectroscopy

Analytical and Bioanalytical Chemistry - VLSI devices are almost exclusively fabricated on Czochralski (CZ) silicon containing high concentrations of interstitially dissolved oxygen ([Oi] ∼...     

Boron implantation in Si: Channeling effects studied by SIMS and simulation

The axial channeling behaviour of boron implants in <100>, <110> and <111> silicon wafers is investigated by SIMS. Large differences of channeling characteristics such as channeled projected range (the projected range of channeled ions or channeling peak) and the fraction of channeled to implanted ions are observed among the three major crystal orientations. Within the critical angle, the channeling behaviour is very sensitive to the incidence beam angle with respect to crystal orientations. SIMS measurements are performed at different positions along several critical directions over a whole wafer. Well channeled profiles with an incidence beam angle to crystal orientations of 0 ° are obtained for each ion implantation energy and orientation. The results are used to test various models of ion implantation by simulation. A 3-parameter model for electronic stopping power of boron in silicon was proposed.     

Novel separation method for highly sensitive speciation of cancerostatic platinum compounds by HPLC–ICP–MS

A high-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICP–MS) method is presented for analysis of cisplatin, monoaquacisplatin, diaquacisplatin, carboplatin, and oxaliplatin in biological and environmental samples. Chromatographic separation was achieved on pentafluorophenylpropyl-functionalized silica gel. For cisplatin, carboplatin, and oxaliplatin limits of detection of 0.09, 0.10, and 0.15 g L^–1, respectively, were calculated at m/z 194, using aqueous standard solutions. (3 L injection volume). The method was utilized for model experiments studying the stability of carboplatin and oxaliplatin at different chloride concentrations simulating wastewater and surface water conditions. It was found that a high fraction of carboplatin is stable in ultrapure water and in solutions containing 1.5 mol L^–1 Cl^–, whereas oxaliplatin degradation was increased by increasing the chloride concentration. In order to support the assessment of oxaliplatin eco-toxicology, the method was tested for speciation of patient urine. The urine sample contained more than 17 different reaction products, which demonstrates the extensive biotransformation of the compound. In a second step of the study the method was successfully evaluated for monitoring cancerostatic platinum compounds in hospital waste water.     

Comparison of sample preparation methods for the ICP-AES determination of minor and major elements in clarified apple juices

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the determination of minor and major elements present in apple juices. Prior to ICP-AES measurement, samples were diluted with nitric acid or digested in a microwave assisted digestion system. The differences in the measured element concentrations after application of different types of sample preparation procedures are discussed. The direct measurement compared to closed microwave dissolution was found to be the best sample preparation procedure. Prior to the measurements the ICP-AES method was validated and optimized for the determination of elements in apple juices. For diluted apple juice samples the lowest limits of detection (LOD) were obtained for Ba and Cd (< 20 μg L^{− 1}), moderate ones for Cu, Mn, Ni, Fe, Ag, Ca, Cr, Zn, Mg, and Sr (20–100 μg L^{− 1}), and the highest LODs for K, Pb, Na, and Al (> 110 μg L^{− 1}). The results obtained for the repeatability (< 0.9%), the intermediate precision (< 4.5%), the day-to-day reproducibility (< 5.2%), and the overall uncertainty of measurement (approx. 4–7%) for all elements analyzed demonstrated the good applicability of the proposed method. Differences in major element content in fresh and commercial apple juice are discussed.     

Trends in surface and interface analysis

Summary The rapid progress in high technology constantly poses new challenges for Analytical Chemistry and prompts the development of new techniques and procedures. The influence is particularly strong in surface and interface analysis, which is developing at a rapid pace. This paper discusses some of the frontier areas like high-resolution depth-distribution analysis of trace elements, quantitative depth distribution analysis of ultra thin-layer systems, quantitative trace element analysis in monolayers, 3-dimensional stereometric analysis, molecular analysis, in-situ atomic resolution analysis of surfaces (chemical nanoscopy). Methodological approaches are discussed as well as results obtained mainly with solid state mass spectrometry and atomic force microscopy.Abbreviations and acronyms AES Auger Electron Spectrometry - AEM Analytical Electron Microscopy - AFM Atomic Force Microscopy - BSE Back Scattered Electrons - EPMA Electron Probe Micro Analysis - LRI-SNMS Laser Resonance Ionization Sputtered Neutrals Mass Spectrometry - SE Secondary Electrons - SEM Scanning Electron Microscopy - SIMS Secondary Ion Mass Spectrometry - STM Scanning Tunneling Microscopy - TEM Transmission Electron Microscopy - TOF-MS Time-of-Flight Mass Spectrometer - TXRF Total Reflection X-Ray Spectrometry - XPS X-Ray Photoelectron Spectroscopy Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Analytical science for the development of microelectronic devices

Summary The new technical revolution, the development and introduction of microelectronics poses a great challenge for Analytical Chemistry: the material and process related analytical problems largely refer to extremely small concentrations and spatial dimensions. A successful treatment of such problems is only possible through the use of the most modern, mainly physical techniques, for which reason it seems appropriate to speak of Analytical Science.This paper tries to demonstrate the potential of Analytical Science for the development of sophisticated microelectronic devices, taking as an example the most highly integrated circuit, the Direct Random Access Memory (DRAM). Referring to the various steps of production of such a device in MOS. technology the most important analytical problems and their treatment with analytical methods are discussed: purity and chemical surface structure of silicon wafers, behaviour of dopant elements during the basic operations of MOS technology (oxidation, implantation, annealing), chemical and physical features of metallization layers, and functional and chemical investigation of devices. Special emphasis is placed on the behaviour of the dopant elements which are decisive for the electrical properties of a device. It is shown that mainly physical analytical techniques like SIMS, NAA, RBS, TEM provide valuable new and quantitative information about the chemical and physical processes occurring in the semiconductor material during production of a device. This information enables substantial progress in process modelling, which is an important basis for further development of devices towards higher integration and complexity.

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Analytische Wissenschaft für die Entwicklung mikroelektronischer Bauelemente

Zusammenfassung Die neue technologische Revolution, nämlich Entwicklung und Einführung der Mikroelektronik, stellt für die Analytische Chemie eine der größten Herausforderungen dar: Die material- und prozeßbezogenen Fragestellungen beziehen sich nämlich in hohem Maße auf extrem kleine Konzentrationen und räumliche Dimensionen. Eine erfolgreiche Behandlung derartiger Fragestellungen ist nur durch Einsätz modernster, überwiegend auf der Physik basierender Hochleistungsanalytik (Analytische Wissenschaft) möglich.In der vorliegenden Arbeit wird versucht, die Rolle dieser Analytischen Wissenschaft für die Entwicklung mikroelektronischer Bauelemente am Beispiel des höchstintegrierten Direct Random Access Memory (DRAM) darzustellen. Ausgehend von den verschiedenen Stufen der Herstellung eines solchen Bauelementes in MOS-Technologie werden die wichtigsten analytischen Fragestellungen und deren Behandlung mit analytischen Methoden diskutiert: Reinheit und chemische Oberflächenstruktur der Siliciumwafer, Verteilung und Reaktionen der Dotierungselemente während der Grundoperationen des MOS-Prozesses (Oxidation, Implantation, Ausheilung), chemische und physikalische Eigenschaften der Metallisierungsstrukturen und funktionelle sowie chemische Untersuchungen der Bauelemente. Besonders eingegangen wird auf die Dotierungselemente, welche die elektrischen Eigenschaften eines Bauelementes bestimmen. Es wird gezeigt, daß in erster Linie physikalische Methoden wie SIMS, NAA, RBS, TEM wichtige neue und quantitative Informationen über die bei der Herstellung eines Bauelementes im Halbleiter ablaufenden chemischen und physikalischen Prozesse liefern. Diese Informationen ermöglichen wesentliche Verbesserungen in der Modellierung dieser Prozesse. Dies ist wiederum eine wesentliche Grundlage für die Weiterentwicklung mikroelektronischer Bauelemente in Richtung höherer Integration und Komple-xität.

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Symbols used d _A diameter of analyzed volume - d _z depth of analyzed volume - (rel) DL (relative) detection limit - E _o excitation energy - iB (primary) beam intensity Dedicated to Prof. Dr. K. Komarek on the occasion of his 60th birthday     

Analytische Charakterisierung von Phosphor in Hartmetallen und Rohstoffen

Zusammenfassung Es wird über die metallurgische Bedeutung und die analytische Charakterisierung von Spurengehalten von Phosphor in Hartmetallen und deren Ausgangsprodukten berichtet. Für die quantitative Durchschnittsanalyse von Phosphorgehalten von wenigen g/g kann SIMS erfolgreich eingesetzt werden. Diese Methode verfügt über die entsprechende Nachweisstärke sowie ausreichende Richtigkeit und ermöglicht es, die Herkunft der Phosphorspuren und die Änderung des Phosphorgehaltes beim Sintern zu ermitteln. Die Verteilungsanalyse an Bruchflächen mit Scanning-AES liefert die wichtige Information, daß P in einer nur wenigen Nanometer dicken Interfacezone zwischen den Carbidphasen angereichert vorliegt.

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Analytical characterization of phosphorus in hard metals and raw materials

Summary The metallurgical significance and the analytical characterization of trace amounts of P in hard metals and raw materials is discussed. For quantitative bulk analysis in the low (g/g-range SIMS can be used sucessfully. This method provides the necessary detection power and results of sufficient accuracy and enables to explain the origin of these trace contents of P and the study of the change of the P-concentration during sintering. Distribution analysis of fracture surfaces with Scanning AES yields the important information that P is mainly present in an interface zone of a few nanometers thickness between the carbide phases.

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Hartmetall eine metallurgische Signifikanz haben und die mechanischen Eigenschaften des resultierenden Hartmetalls verändern können.     

Ultra-trace analysis of platinum in human tissue samples

Background levels of platinum were determined in human autopsy tissues taken from five individuals. The investigated specimens were lung, liver and kidney. Sample preparation involved microwave digestion followed by an open vessel treatment. Inductively-coupled plasma sector field mass spectrometry (ICP-SFMS) was applied in combination with an ultrasonic nebulization/membrane desolvation system for sample introduction. Isotope dilution analysis was employed for accurate quantification of platinum. Excellent procedural detection limits (3 s validation) of 20, 20 and 34 pg g^–1 dry weight were obtained for lung, liver and kidney tissue, respectively. Due to the lack of appropriate biological reference material, road dust (BCR-723) was used for method validation. Platinum levels ranging between 0.03 and 1.42 ng g^–1 were determined in the investigated samples. The platinum concentrations observed in human lung tissue may reflect the increasing atmospheric background levels of platinum originating from car catalysts. The presence of platinum in kidney and liver tissue samples clearly indicates the bioavailability of the element.     

Transient SIMS depth-profiles at the interface Si3N4/GaAs

Summary A transient secondary ion signal enhancement during sputtering through the interface of a two-layer target of Si₃N₄/GaAs could be demonstrated to be an artefact caused by the bombardment with oxygen ions, which were used as a primary beam. A simple model is established which describes ion-induced composition changes during sputtering (sputter-emission and recoil implantation from the surface, cascade mixing, and implantation of projectiles). The application of this model permits the simulation of internal profiles of a trace element, the matrix atoms and of implanted primary ions, and consequently the simulation of the emitted particle flux during sputtering. These calculations indicate an accumulation of implanted primary ions at the GaAs-side of the interface which considerably enhances the yield of positive secondary ions in this zone. The calculated response fits experimental data within a factor of less than 2.

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Quantitative SIMS-Analyse an der Grenzfläche Si₃N₄/GaAs

Zusammenfassung Bei der Analyse von Verunreinigungen (Chrom) in Si₃N₄-Schichten auf GaAs mit der Sekundärionen-Massenspektrometrie (SIMS) tritt am Schichtübergang ein transienter Anstieg der Intensität positiver Sekundärionen von Chrom und Arsen auf. Es wird experimentell gezeigt, daß dieser Anstieg nicht auf das Vorhandensein einer parasitären Zwischenschicht aus Chrom oder eines Oxides, sondern auf den Beschuß mit einem Sauerstoff-Primärstrahl zurückzuführen ist. Es wurde ein einfaches Modell erstellt, das die ioneninduzierten Veränderungen der gesputterten Probe beschreibt (Sputter-Emission und Recoil-Implantation aus der Oberfläche, Vermischung der Matrixatome durch Kaskadenmischung, Implantation der Primärionen). Die numerische Simulation der SIMS-Messung durch Anwendung dieses Modelles auf die untersuchten Proben zeigt eine Anhäufung implantierter Primärionen knapp hinter dem Schichtübergang. Im Fall von Sauerstoff erhöht dieser lokal die Ausbeute an positiven Sekundärionen. Der erechnete Verlauf dieser Signalüberhöhung stimmt innerhalb eines Faktors < 2 mit den Experimenten überein.