Дисертації з теми "Implantation damage"

L’endommagement induit par implantation d’hélium dans le carbure de silicium a été étudié par DRX et TEM. La simulation des spectres DRX a permis de tracer les profils de déformation. Les implantations ont été réalisées à températures ambiante (TA) et élevées sur une large gamme de fluences. Les expériences menées à TA ont montré que l’endommagement résulte de mécanismes liés à la fois aux défauts ponctuels et à des complexes hélium-lacunes. Des seuils ont été estimés pour la formation de couches de bulles et de matériau amorphe. Contrairement à ce qui est admis, la densité d’énergie nucléaire critique pour observer la transition amorphe dépend de l’énergie des ions incidents. Pour des températures d’implantation élevées, deux régimes d’endommagement sont distingués selon la fluence. Aux faibles fluences, un recuit dynamique proportionnel à la concentration en défauts est observé. Aux fortes fluences, une migration des défauts de type interstitiel vers la zone de fort endommagement a été mise en évidence. Celle-ci conduit à une saturation de la déformation en surface du matériau. Enfin, des recuits ont été réalisés sur les échantillons implantés à TA. Différents stades de recuit des défauts ponctuels ont été mis en évidence et associés à des énergies d’activation. Pendant le recuit, une forte évolution de la microstructure a été constatée dans la zone de fort endommagement. Pour des fluences évitant l’amorphisation, des amas de bulles en surpression se forment à partir de cavités lenticulaires. Ces bulles expulsent des boucles de dislocations créant de la déformation plastique dans le matériau
In this work, the damage induced by helium implantation in silicon carbide has been studied through XRD and TEM experiments. Combining both XRD experiments and simulations has led us to obtain accurate strain profiles. Implantations have been performed from RT to elevated temperatures to a wide range of fluences. Implantation at RT has been shown to result in a complex picture with mechanisms related to both point defects and helium-vacancy complexes. In particular, helium-vacancy complexes have been seen to strongly influence the strain profile for a concentration of helium exceeding 0. 5%. Thresholds for the formation of layers of bubbles and amorphous material have been estimated. This latter depends on the energy of incident ions contrary to what is currently acknowledged. Experiments at elevated temperatures have pointed out two regimes in the damage production as a function of fluence. In the low fluence regime, dynamic annealing occurs in proportion to the defect density over the whole implanted zone. In the high fluence regime, in addition to the dynamic annealing, a migration of interstitial-type defects towards a highly damaged zone has been detected. Both phenomenon lead to a saturation in the near surface strain. Finally, annealing has been performed on the samples implanted at RT. Annealing stages of point defects have been distinguished and related to activation energies. During annealing, strong evolution of the microstructure has been seen to take place in the highly damaged zone. At medium fluences, platelets are formed that collapse into clusters of overpressurized bubbles. These latter induce loop punching which in turn, induces plastic deformation

Le carbure de silicium (SiC) est un matériau qui est considéré comme un semi-conducteur à large bande interdite ou une céramique suivant ses applications en microélectronique ou comme matériau nucléaire. Dans ces deux domaines d'application les défauts générés par l'implantation/irradiation d'ions (dopage, matériau de structure) doivent être contrôlés. Ce travail est une étude des défauts générés par l'implantation de gaz rares suivant les conditions d'implantation (fluence et température). La déformation élastique a plus particulièrement été étudiée dans le cas d'implantation de xénon à des températures pour lesquelles la recombinaison dynamique empêche la transition amorphe. Un modèle phénoménologique basé sur le recouvrement des cascades a été proposé pour comprendre l'évolution de la déformation maximale avec la dose. Des observations complémentaires en particulier par microscopie électronique à transition nous ont permis de préciser la nature des défauts créés et d'étudier leur évolution sous recuit. La formation de cavités a été observée pour des conditions sévères d'implantation/recuit ; ces cavités sont de nature différente (vide ou pleine) suivant la répartition du xénon. Cette étude est également reliée aux propriétés de gonflement sous irradiation, gonflement qui doit être anticipé dans les domaines d'application du SiC
Silicon carbide is a material that can be considered as a wide band gap semiconductor or as a ceramic according to its applications in microelectronics and in nuclear energy system (fission and fusion). In both fields of application defects or damage induced by ion implantation/ irradiation (doping, material structure) should be controlled. This work is a study of defects induced by noble gas implantation according to the implantation conditions (fluence and temperature). The elastic strain buildup, particularly in the case of xenon implantation, has been studied at elevated temperatures for which the dynamic recombination prevents the amorphization transition. A phenomenological model based on cascade recovery has been proposed to understand the strain evolution with increasing dose and for different noble gases. In addition, with the help of transmission electron microscopy the evolution of defects under subsequent annealing was studied. The formation of nanocavities was observed under severe implantation/annealing conditions. These cavities are of different nature (full of gas or empty) according to the xenon and damage distribution. This study is also linked to swelling properties under irradiation that should be projected in the SiC application fields

A new understanding of the damage formation mechanisms in Si is developed and investigated over an extended range of ion energy, dose, and irradiation temperature. A simple model for dealing with ion-induced damage is proposed, which is shown to be applicable over the range of implantation conditions. In particular the concept of defect "excesses" will be discussed. An excess exists in the lattice when there is a local surplus of one particular type of defect, such as an interstitial, over its complimentary defect (i.e., a vacancy). Mechanisms for producing such excesses by implantation will be discussed. The basis of this model specifies that accumulation of stable lattice damage during implantation depends upon the excess defects and not the total number of defects. The excess defect model is validated by fundamental damage studies involving ion implantation over a range of conditions. Confirmation of the model is provided by comparing damage profiles after implantation with computer simulation results. It will be shown that transport of ions in matter (TRIM) can be used effectively to model the ion-induced damage profile, i.e. excess defect distributions, by a simple subtraction process in which the spatially correlated defects are removed, thereby simulating recombination. Classic defect studies illuminate defect interactions from concomitant implantation of high- and medium-energy Si+-self ions. Also, the predictive quality of the excess defect model was tested by applying the model to develop several experiments to engineer excess defect concentrations to substantially change the nature and distribution of the defects. Not only are the excess defects shown to play a dominant role in defect-related processing issues, but their manipulation is demonstrated to be a powerful tool in tailoring the implantation process to achieve design goals. Pre-amorphization and dual implantation of different energetic ions are two primary investigative tools used in this work. Various analyses, including XTEM, RBS/channeling, PAS, and SIMS, provided experimental verification of the excess defect model disseminated within this dissertation.

Group-III-nitride semiconductors (GaN, InGaN, and AlGaN) are important for the fabrication of a range of optoelectronic devices (such as blue-green light emitting diodes, laser diodes, and UV detectors) as well as devices for high-temperature/high-power electronics. In the fabrication of these devices, ion bombardment represents a very attractive technological tool. However, a successful application of ion implantation depends on an understanding of the effects of radiation damage. Hence, this thesis explores a number of fundamental aspects of radiation effects in wurtzite III-nitrides. Emphasis is given to an understanding of (i) the evolution of defect structures in III-nitrides during ion irradiation and (ii) the influence of ion bombardment on structural, mechanical, optical, and electrical properties of these materials. ¶ Structural characteristics of GaN bombarded with keV ions are studied by Rutherford backscattering/channeling (RBS/C) spectrometry and transmission electron microscopy (TEM). Results show that strong dynamic annealing leads to a complex dependence of the damage buildup on ion species with preferential surface disordering. Such preferential surface disordering is due to the formation of surface amorphous layers, attributed to the trapping of mobile point defects by the GaN surface. Planar defects are formed for a wide range of implant conditions during bombardment. For some irradiation regimes, bulk disorder saturates below the amorphization level, and, with increasing ion dose, amorphization proceeds layer-by-layer only from the GaN surface. In the case of light ions, chemical effects of implanted species can strongly affect damage buildup. For heavier ions, an increase in the density of collision cascades strongly increases the level of stable implantation-produced lattice disorder. Physical mechanisms of surface and bulk amorphization and various defect interaction processes in GaN are discussed. ¶ Structural studies by RBS/C, TEM, and atomic force microscopy (AFM) reveal anomalous swelling of implanted regions as a result of the formation of a porous structure of amorphous GaN. Results suggest that such a porous structure consists of N$_{2}$ gas bubbles embedded into a highly N-deficient amorphous GaN matrix. The evolution of the porous structure appears to be a result of stoichiometric imbalance, where N- and Ga-rich regions are produced by ion bombardment. Prior to amorphization, ion bombardment does not produce a porous structure due to efficient dynamic annealing in the crystalline phase. ¶ The influence of In and Al content on the accumulation of structural damage in InGaN and AlGaN under heavy-ion bombardment is studied by RBS/C and TEM. Results show that an increase in In concentration strongly suppresses dynamic annealing processes, while an increase in Al content dramatically enhances dynamic annealing. Lattice amorphization in AlN is not observed even for very large doses of keV heavy ions at -196 C. In contrast to the case of GaN, no preferential surface disordering is observed in InGaN, AlGaN, and AlN. Similar implantation-produced defect structures are revealed by TEM in GaN, InGaN, AlGaN, and AlN. ¶ The deformation behavior of GaN modified by ion bombardment is studied by spherical nanoindentation. Results show that implantation disorder significantly changes the mechanical properties of GaN. In particular, amorphous GaN exhibits plastic deformation even for very low loads with dramatically reduced values of hardness and Young's modulus compared to the values of as-grown GaN. Moreover, implantation-produced defects in crystalline GaN suppress the plastic component of deformation. ¶ The influence of ion-beam-produced lattice defects as well as a range of implanted species on the luminescence properties of GaN is studied by cathodoluminescence (CL). Results indicate that intrinsic lattice defects mainly act as nonradiative recombination centers and do not give rise to yellow luminescence (YL). Even relatively low dose keV light-ion bombardment results in a dramatic quenching of visible CL emission. Postimplantation annealing at temperatures up to 1050 C generally causes a partial recovery of measured CL intensities. However, CL depth profiles indicate that, in most cases, such a recovery results from CL emission from virgin GaN, beyond the implanted layer, due to a reduction in the extent of light absorption within the implanted layer. Experimental data also shows that H, C, and O are involved in the formation of YL. The chemical origin of YL is discussed based on experimental data. ¶ Finally, the evolution of sheet resistance of GaN epilayers irradiated with MeV light ions is studied {\it in-situ}. Results show that the threshold dose of electrical isolation linearly depends on the original free electron concentration and is inversely proportional to the number of atomic displacements produced by the ion beam. Furthermore, such isolation is stable to rapid thermal annealing at temperatures up to 900 C. Results also show that both implantation temperature and ion beam flux can affect the process of electrical isolation. This behavior is consistent with significant dynamic annealing, which suggests a scenario where the centers responsible for electrical isolation are defect clusters and/or antisite-related defects. A qualitative model is proposed to explain temperature and flux effects. ¶ The work presented in this thesis has resulted in the identification and understanding of a number of both fundamental and technologically important ion-beam processes in III-nitrides. Most of the phenomena investigated are related to the nature and effects of implantation damage, such as lattice amorphization, formation of planar defects, preferential surface disordering, porosity, decomposition, and quenching of CL. These effects are often technologically undesirable, and the work of this thesis has indicated, in some cases, how such effects can be minimized or controlled. However, the thesis has also investigated one example where irradiation-produced defects can be successfully applied for a technological benefit, namely for electrical isolation of GaN-based devices. Finally, results of this thesis will clearly stimulate further research both to probe some of the mechanisms for unusual ion-induced effects and also to develop processes to avoid or repair unwanted lattice damage produced by ion bombardment.

Actualmente la implantación de prótesis aórtica transcatéter (TAVI) representa la principal opción terapéutica para pacientes con estenosis aórtica severa y alto riesgo quirúrgico. La ampliación de las indicaciones TAVI a una población de menor riesgo está limitada por la relativa alta incidencia de eventos cerebrovasculares. El daño neurológico relacionado con la TAVI se ha clasificado en distintos niveles: clínico (ictus y accidente cerebral transitorio); subclínico (infartos silentes detectados por resonancia magnética con ponderación de difusión [DWI]); y cognitivo. Estudios con DWI realizados en pacientes con un perfil de riesgo elevado han mostrado una alta incidencia de daño cerebral subclínico tras la TAVI. No obstante, la repercusión clínica en forma de variaciones del estado cognitivo ha mostrado resultados poco concluyentes. Tampoco conocemos el riesgo de daño subclínico ni las consecuencias cognitivas en una población TAVI con un perfil de riesgo menor. Existen dos principales estrategias para prevenir el daño neurológico asociado a la TAVI: farmacológica (agentes antitrombóticos) y mecánica (dispositivos de protección embólica). Las guías de práctica clínica recomiendan una terapia antiplaquetar (TAP) post-TAVI para reducir el riesgo de ictus. No obstante, no hay datos sobre la eficacia y seguridad de esta recomendación en pacientes que se encuentren en tratamiento concomitante con antagonistas de la vitamina K (AVK) por fibrilación auricular (FA). El primer objetivo (estudio 1) fue comparar el grado de daño neurológico subclínico (mediante DWI) y las variaciones del estado cognitivo entre la TAVI y el recambio valvular aórtico quirúrgico (RVA) en una población considerada de riesgo quirúrgico intermedio. El segundo objetivo fue examinar el riesgo de eventos isquémicos y hemorrágicos asociados a dos estrategias antitrombóticas distintas en pacientes con FA sometidos a TAVI. Los dos estudios presentados son observacionales. El estudio 1 se realizó en el Hospital Vall Hebron. Cuarenta y seis pacientes sometidos a TAVI (78,8±8.3 años, STS score 4,4±1.7) se compararon con 37 pacientes sometidos a RVA (78,9±6,2 años, STS score 4,7±1,7). La DWI se realizó durante los primeros 15 días tras la intervención y la valoración cognitiva a nivel basal y a los 3 meses tras la intervención. No se observaron diferencias en la incidencia de ictus (2,2% en TAVI vs. 5,4% en RVA, p=0.58), ni en la incidencia de lesiones cerebrales subclínicas detectadas por DWI (45% vs. 40,7%, OR-ajustada 0,95 [0,25-3,65], p=0,94). La edad fue un predictor de nuevas lesiones (p=0,01), y el tratamiento con antagonistas de la vitamina K (AVK) tuvo un efecto protector (p=0,037). No se observaron cambios significativos en las puntuaciones de los test cognitivos tras la intervención. El estudio 2 incluyó a 621 pacientes con FA sometidos a TAVI. Se compararon dos estrategias antitrombóticas utilizadas en mundo real: monoterapia (MT) con el uso único de AVK (n=101) vs. terapia multi-antitrombótica (MAT) con el uso de TAP más AVK (n=520). Durante un seguimiento medio de 13 meses no se observaron diferencias en la incidencia de ictus (p=0.67), eventos cardiovasculares mayores (combinado de ictus, infarto o muerte cardiaca, p=0.33), o muerte (p=0.76). No obstante sí se documentó un mayor riesgo de hemorragia mayor o amenazante en el grupo MAT (HR 1,85 [1,05-3,28], p=0,04). El estudio 1 mostró que en una población de riesgo intermedio el daño neurológico tras la TAVI fue similar que tras el RVA. Aunque la incidencia de daño subclínico era elevada (tras la TAVI o RVA) su impacto clínico no pareció relevante. En el estudio 2 se observó que añadir una TAP a pacientes que están en tratamiento con AVK por FA y son sometidos a TAVI no aportó ningún beneficio y en cambio sí aumentó el riesgo de hemorragia.
Transcatheter aortic valve implantation (TAVI) is now the principal therapeutic option in patients with severe aortic stenosis deemed at high surgical risk. Implementing TAVI in a lower risk profile population could be limited by relatively high incidence of neurological damage related with the procedure. Neurological damage has been classified at different levels: clinical (stroke or transient ischemic attack), subclinical (silent embolic infarcts after procedure demonstrated by Diffusion Weighted resonance Imaging [DWI]), and cognitive. DWI studies performed in high risk patients have demonstrated the ubiquitous presence of subclinical damage following TAVI. However its effects on cognition showed inconclusive results. To date, the risk of subclinical damage and cognitive fluctuations following TAVI in a population deemed at lower risk is unknown. There are currently two main strategies to prevent neurological damage related with TAVI: pharmacological (antithrombotic agents) and mechanical (embolic protection devices). Guidelines recommend antiplatelet therapy (APT) post-TAVR to reduce the risk of stroke. However, data on the efficacy and safety of this recommendation in the setting of a concomitant indication for oral anticoagulation (due to atrial fibrillation [AF]) are scare. The first objective (study 1) was to compare the degree of neurological damage using DWI and cognitive testing between TAVI and surgical aortic valve implantation (SAVR) in patients deemed at intermediate surgical risk. The second objective (study 2) was to examine the risk of ischemic events and bleeding episodes associated with differing antithrombotic strategies in patients undergoing TAVI with concomitant AF. The two studies presented were observational. Study #1 was conducted in Vall Hebron Hospital. Forty-six patients undergoing TAVI (78.8±8.3 years, STS score 4.4±1.7) and 37 patients undergoing SAVR (78.9±6.2 years, STS score 4.7±1.7) were compared. DWI was performed within the first 15 days post-procedure. A cognitive assessment was performed at baseline and at 3 months follow-up. TAVI and SAVR groups were comparable in terms of baseline characteristics. There were no differences in incidence of stroke (2.2% in TAVR vs. 5.4% in SAVR, p=0.58), neither in the rate of acute ischemic cerebral lesions detected by DWI (45% vs. 40.7%, adjusted OR 0.95 [0.25-3.65], p=0.94). An older age was a predictor of new lesions (p=0.01), and therapy with vitamin K antagonist (VKA) had a protective effect (p=0.037). Overall no significant changes were observed in global cognitive scores post-intervention. Study #2 was a real world multicenter evaluation comprising 621 patients with AF undergoing TAVI. Two groups were compared: mono-therapy (MT) group (with the use of VKA alone, n=101) vs. multi-antithrombotic (MAT) group (with the use of VKA plus APT, as recommended by guidelines, n=520). During a follow-up of 13 months there were no differences between groups in the rates of stroke (MT 5% vs. MAT 5.2%, HR 1.25 [0.45-3.48], p=0.67), major cardiovascular endpoint (combined of stroke, myocardial infarction or cardiovascular death, p=0.33) or death (p=0.76), however a higher risk of major or life-threatening bleeding was found in the MAT group (HR 1.85 [1.05-3.28], p=0.04). Study #1 found similar rate of cerebral damage following TAVI and SAVR in patients at intermediate risk. Although acute lesions occurred frequently in both strategies, their cognitive impact was not clinically relevant. Study #2 found that in TAVI recipients prescribed VKA therapy for AF, concomitant APT use appears not to reduce the incidence of stroke, major adverse cardiovascular events, or death, while increasing the risk of major or life-threatening bleeding. Though only observational, the important lessons to be drawn from this thesis are that under a neurological perspective implementing TAVI in an intermediate risk populations appears reasonable; and that the currently recommendation of prescribing APT for patients with AF who are already on long-term anticoagulation does not confer any benefit while potentially being harmful.

In the absence of a fusion neutron source, research on the structural integrity of materials in the fusion environment relies on current fission data and simulation methods. Through investigation of the Fe-Cr system, this detailed study explores the challenges and limitations in the use of currently available radiation sources for fusion materials research. An investigation of ion-irradiated Fe12%Cr using nanoindentation with a cube corner, Berkovich and spherical tip, and micro-cantilever testing with two different geometries, highlighted that the measurement of irradiation hardening was largely dependent on the type of test used. Selected methods were used for the comparison of Fe6%Cr irradiated by ions and neutrons to a dose of 1.7dpa at a temperature of 288°C. Micro-cantilever tests of the Fe6%Cr alloy with beam depths of 400 to 7000nm, identified that size effects may significantly obscure irradiation hardening and that these effects are dependent on radiation conditions. Irradiation hardening in the neutron-irradiated alloy was approximately double that of the ion-irradiated alloy and exhibited increased work hardening. Similar differences in hardening were observed in an Fe5%Cr alloy after ion-irradiation to a dose of 0.6dpa at 400°C and doses rates of 6 x 10^-4dpa/s and 3 x 10^-5dpa/s. Identified by APT, it was shown that increased irradiation hardening was likely to be caused by the enhanced segregation of Cr observed in the alloy irradiated with the lower dose rate. These observations have significant implications for future fusion materials research in terms of the simulation of fusion relevant radiation conditions and micro-mechanical testing.

Afin d'optimiser les performances des circuits intégrés, l’industrie de la micro et nanotechnologie mène d'intenses recherches sur la miniaturisation à l'échelle sub-22nm de leurs principaux constituants que sont les transistors MOS. La réduction de la taille de grille atteint néanmoins des limites qui rendent problématique le contrôle du canal. L'une des approches les plus prometteuses pour contourner ce dilemme et ainsi poursuivre la miniaturisation des futurs nœuds technologiques, consiste au développement des transistors d’architectures 3D (Trigate ou FinFET). La mise au point de telles structures requiert une caractérisation de plus en plus fine, surtout à une étape clé de leur élaboration, qui est celle du dopage par implantation ionique. Du fait des faibles profondeurs implantées, l'analyse par diffusion d'ions de moyenne énergie (MEIS) est tout à fait adaptée pour quantifier les implants et évaluer la conformité du dopage grâce à sa bonne résolution en profondeur (0.25 nm). Néanmoins, les dimensions de la sonde (0.5 × 1 mm2) étant très supérieures à celles des motifs, il nous a fallu développer un protocole d’analyse propre à de telles architectures. Les échantillons étudiés dans le cadre de cette thèse sont des systèmes modèles. Ils sont constitués de réseaux de lignes de silicium (Si) 3D, formées par gravure lithographique par faisceaux d’électrons (e-beam) sur des plaques 300 mm de types silicium sur isolant (SOI). Le dopage a été réalisé à une énergie de 3 keV par implantions conventionnelle (ou beam line) et immersion plasma (PIII).L’analyse des spectres MEIS des implants insérés dans chaque facette des motifs a été possible grâce aux simulations 3D types Monte-Carlo effectuées avec le logiciel PowerMEIS. Nous avons ainsi développé une nouvelle méthode adaptée à la caractérisation du dopage 3D. Les mesures ont montré que, contrairement à la méthode PIII, la dose implantée par la méthode conventionnelle correspond à celle visée. Cependant la distribution des dopants introduits au sein des nanostructures par les deux méthodes de dopage n’est pas uniforme. Dans les échantillons implantés par PIII, on a observé une importante concentration des dopants aux sommets des motifs et un faible dopage des flancs. Ceci étant moins marqué dans celui implanté par la méthode conventionnelle. En corrélant les techniques de Microscopie Electronique en Transmission (MET), d’analyses par rayons x synchrotron et MEIS, nous avons également pu déterminer les dimensions des zones implantées ainsi que celles des zones cristallines dans les réseaux de lignes gravées.L'exploitation de la technique MEIS en mode canalisation a permis une évaluation complète des couches non gravées. L’investigation des endommagements post – dopage dans les régions cristallines non implantées ont été menées toujours avec la même technique MEIS. Les résultats ont révélé une importante influence de la méthode d’implantation et la température sur les défauts et les déformations dans le cristal. L’origine des anomalies au sein des échantillons a ainsi été identifiée en corrélant les mesures MEIS et celles par spectrométrie de masse des ions secondaires en temps de vol (ToF-SIMS)
With the aim of optimizing the performances of integrated circuits (ICs), the nanotechnology industry is carrying out intense research activities on the miniaturization at the sub-22 nm scale of their main constituents: the MOS transistors. Nevertheless, the shrinking of the gate size has reached the limits that make the control of the channel problematic. One of the most promising approaches to circumvent this dilemma and thus further the miniaturization of the future technological nodes, is the development of transistors of 3D architecture (Trigate or FinFET). The elaboration of such nanostructures requires increasingly fine characterization tools precisely at a key stage of their fabrication, namely the ion implantation doping. Given the ultra-shallow implantation depths, the medium energy ion scattering (MEIS) analysis technique is suitable for quantifying the implants and evaluating the doping conformity thanks to its good depth resolution (0.25 nm). However, the dimensions of the beam (0.5×1 mm2) being by far larger than those of the patterns, we had to develop an analysis protocol dedicated to such architectures. The samples studied in the framework of this thesis are considered as model systems. They are constituted of 3D silicon (Si) Fin – shaped line gratings, etched on the 300 mm wafers of silicon on insulator (SOI) types by using the electron beam (e-beam) lithography. The doping has been carried out at an energy of 3 keV by using the conventional (or beam line) and plasma immersion ion implantation (PIII) methods.The analyses s of the MEIS spectra of the dopants implanted into each part of the patterns were possible thanks to the 3D Monte-Carlo simulations performed with the PowerMEIS software. We have thus developed a new method suitable for the characterization of the 3D doping. The measurements have shown that, contrarily to the PIII method, the dose implanted by the conventional method is as targeted. However, the distribution of the dopants inserted within the nanostructures by using the two doping methods is not uniform. In the PIII implanted samples, a large dopants' focusing at the tops of the patterns and low sidewalls' doping have been observed. This is less marked in the one implanted by the conventional method. By correlating the Transmission Electron Microscopy (TEM), synchrotron x – ray analyses and MEIS, we have also determined the dimensions of the implanted and crystal areas of the line gratings.The exploitation of the MEIS technique in channeling mode has permitted the full assessment of the impacts of the implantation in the non-etched layers. The investigations of the crystal qualities in the non-implanted areas were carried out with the same technique. The results show that the temperature conditions have a considerable influence on the defects and lattice deformations. The origin of the anomalies in the samples has thus been identified by correlating the MEIS and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) measurements

In der vorliegenden Arbeit wird erstmals das QQDS-Magnetspektrometer für die höchstauflösende Ionenstrahlanalytik leichter Elemente am Helmholtz-Zentrum Dresden-Rossendorf umfassend vorgestellt. Zusätzlich werden sowohl alle auf die Analytik Einfluss nehmenden Parameter untersucht als auch Methoden und Modelle vorgestellt, wie deren Einfluss vermieden oder rechnerisch kompensiert werden kann. Die Schwerpunkte dieser Arbeit gliedern sich in fünf Bereiche. Der Erste ist der Aufbau und die Inbetriebnahme des QQDS-Magnetspektrometers, der zugehörige Streukammer mit allen Peripheriegeräten und des eigens für die höchstauflösende elastische Rückstoßanalyse entwickelten Detektors. Sowohl das umgebaute Spektrometer als auch der im Rahmen dieser Arbeit gebaute Detektor wurden speziell an experimentelle Bedingungen für die höchstauflösende Ionenstrahlanalytik leichter Elemente angepasst und erstmalig auf einen routinemäßigen Einsatz hin getestet. Der Detektor besteht aus zwei Komponenten. Zum einen befindet sich am hinteren Ende des Detektors eine Bragg-Ionisationskammer, die zur Teilchenidentifikation genutzt wird. Zum anderen dient ein Proportionalzähler, der eine Hochwiderstandsanode besitzt und direkt hinter dem Eintrittsfenster montiert ist, zur Teilchenpositionsbestimmung im Detektor. Die folgenden zwei Schwerpunkte beinhalten grundlegende Untersuchungen zur Ionen-Festkörper-Wechselwirkung. Durch die Verwendung eines Magnetspektrometers ist die Messung der Ladungszustandsverteilung der herausgestreuten Teilchen direkt nach einem binären Stoß sowohl möglich als auch für die Analyse notwendig. Aus diesem Grund werden zum einen die Ladungszustände gemessen und zum anderen mit existierenden Modellen verglichen. Außerdem wird ein eigens entwickeltes Modell vorgestellt und erstmals im Rahmen dieser Arbeit angewendet, welches den ladungszustandsabhängigen Energieverlust bei der Tiefenprofilierung berücksichtigt. Es wird gezeigt, dass ohne die Anwendung dieses Modells die Tiefenprofile nicht mit den quantitativen Messungen mittels konventioneller Ionenstrahlanalytikmethoden und mit der Dickenmessung mittels Transmissionselektronenmikroskopie übereinstimmen, und damit falsche Werte liefern würden. Der zweite für die Thematik wesentliche Aspekt der Ionen-Festkörper-Wechselwirkung, sind die Probenschäden und -modifikationen, die während einer Schwerionen-bestrahlung auftreten. Dabei wird gezeigt, dass bei den hier verwendeten Energien sowohl elektronisches Sputtern als auch elektronisch verursachtes Grenzflächendurchmischen eintreten. Das elektronische Sputtern kann durch geeignete Strahlparameter für die meisten Proben ausreichend minimiert werden. Dagegen ist der Einfluss der Grenzflächendurchmischung meist signifikant, so dass dieser analysiert und in der Auswertung berücksichtigt werden muss. Schlussfolgernd aus diesen Untersuchungen ergibt sich für die höchstauflösende Ionenstrahlanalytik leichter Elemente am Rossendorfer 5-MV Tandembeschleuniger, dass die geeignetsten Primärionen Chlor mit einer Energie von 20 MeV sind. In Einzelfällen, wie zum Beispiel der Analyse von Bor, muss die Energie jedoch auf 6,5 MeV reduziert werden, um das elektronische Sputtern bei der notwendigen Fluenz unterhalb der Nachweisgrenze zu halten. Der vierte Schwerpunkt ist die Untersuchung von sowohl qualitativen als auch quantitativen Einflüssen bestimmter Probeneigenschaften, wie beispielsweise Oberflächenrauheit, auf die Form des gemessenen Energiespektrums beziehungsweise auf das analysierte Tiefenprofil. Die Kenntnis der Rauheit einer Probe an der Oberfläche und an den Grenzflächen ist für die Analytik unabdingbar. Als Resultat der genannten Betrachtungen werden die Einflüsse von Probeneigenschaften und Ionen-Festkörper-Wechselwirkungen auf die Energie- beziehungsweise Tiefenauflösung des Gesamtsystems beschrieben, berechnet und mit der konventionellen Ionenstrahlanalytik verglichen. Die Möglichkeiten der höchstauflösenden Ionenstrahlanalytik werden zudem mit den von anderen Gruppen veröffentlichten Komplementärmethoden gegenübergestellt. Der fünfte und letzte Schwerpunkt ist die Analytik leichter Elemente in ultradünnen Schichten unter Berücksichtigung aller in dieser Arbeit vorgestellten Modelle, wie die Reduzierung des Einflusses von Strahlschäden oder die Quantifizierung der Elemente im dynamischen Ladungszustandsnichtgleichgewicht. Es wird die Tiefenprofilierung von Mehrschichtsystemen, bestehend aus SiO2-Si3N4Ox-SiO2 auf Silizium, von Ultra-Shallow-Junction Bor-Implantationsprofilen und von ultradünnen Oxidschichten, wie zum Beispiel High-k-Materialien, demonstriert
In this thesis the QQDS magnetic spectrometer that is used for high resolution ion beam analysis (IBA) of light elements at the Helmholtz-Zentrum Dresden-Rossendorf is presented for the first time. In addition all parameters are investigated that influence the analysis. Methods and models are presented with which the effects can be minimised or calculated. There are five focal points of this thesis. The first point is the construction and commissioning of the QQDS magnetic spectrometer, the corresponding scattering chamber with all the peripherals and the detector, which is specially developed for high resolution elastic recoil detection. Both the reconstructed spectrometer and the detector were adapted to the specific experimental conditions needed for high-resolution Ion beam analysis of light elements and tested for routine practice. The detector consists of two compo-nents. At the back end of the detector a Bragg ionization chamber is mounted, which is used for the particle identification. At the front end, directly behind the entrance window a proportional counter is mounted. This proportional counter includes a high-resistance anode. Thus, the position of the particles is determined in the detector. The following two points concern fundamental studies of ion-solid interaction. By using a magnetic spectrometer the charge state distribution of the particles scattered from the sample after a binary collision is both possible and necessary for the analysis. For this reason the charge states are measured and compared with existing models. In addition, a model is developed that takes into account the charge state dependent energy loss. It is shown that without the application of this model the depth profiles do not correspond with the quantitative measurements by conventional IBA methods and with the thickness obtained by transmission electron microscopy. The second fundamental ion-solid interaction is the damage and the modification of the sample that occurs during heavy ion irradiation. It is shown that the used energies occur both electronic sputtering and electronically induced interface mixing. Electronic sputtering is minimised by using optimised beam parameters. For most samples the effect is below the detection limit for a fluence sufficient for the analysis. However, the influence of interface mixing is so strong that it has to be included in the analysis of the layers of the depth profiles. It is concluded from these studies that at the Rossendorf 5 MV tandem accelerator chlorine ions with an energy of 20 MeV deliver the best results. In some cases, such as the analysis of boron, the energy must be reduced to 6.5 MeV in order to retain the electronic sputtering below the detection limit. The fourth focus is the study of the influence of specific sample properties, such as surface roughness, on the shape of a measured energy spectra and respectively on the analysed depth profile. It is shown that knowledge of the roughness of a sample at the surface and at the interfaces for the analysis is needed. In addition, the contribution parameters limiting the depth resolution are calculated and compared with the conventional ion beam analysis. Finally, a comparison is made between the high-resolution ion beam analysis and complementary methods published by other research groups. The fifth and last focus is the analysis of light elements in ultra thin layers. All models presented in this thesis to reduce the influence of beam damage are taken into account. The dynamic non-equilibrium charge state is also included for the quantification of elements. Depth profiling of multilayer systems is demonstrated for systems consisting of SiO2-Si3N4Ox-SiO2 on silicon, boron implantation profiles for ultra shallow junctions and ultra thin oxide layers, such as used as high-k materials

In this work tunability, implantation damage and recovery of GaAs doping superlattices implanted with hydrogen ions were studied. The applicability of two models of the optical properties of semiconductors was also investigated. GaAs doping superlattices were implanted with 0.5 MeV hydrogen ions at doses of 1012 cm-2, 1014 cm-2 and 1016 cm-2. This gradually modifies their optical characteristics from superlattice behaviour to something resembling the bulk material and beyond. Such a processing technique therefore provides a convenient way of tuning the optical properties of a superlattice semi-permanently. A combined result of ellipsometry and near infrared reflectance measurements showed that a single effective oscillator as well as a more advanced three-parameter model could be applied to the virgin and ion-implanted doping superlattices. This allowed us to determine the dose dependent effective band gap as well as other model parameters. Photoluminescence as well as normal and resonance Raman techniques were applied to study hydrogen ion implantation damage and its recovery. These techniques showed that implantation damage could be reversed to a large extent by a simple thermal annealing step.
Dissertation (MSc)--University of Pretoria, 2006.
Physics
unrestricted

by Chan Kwok Wai.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1997.
Includes bibliographical references (leaves 93-95).
ACKNOWLEDGEMENT --- p.i
ABSTRACT --- p.ii
LIST OF SYMBOLS --- p.iii
LIST OF FIGURES --- p.v
LIST OF TABLES --- p.vi
Chapter CHAPTER ONE --- INTRODUCTION --- p.1
Chapter CHAPTER TWO --- SURVEYS ON ION IMPLANTATION DAMAGE STUDY --- p.6
Chapter 2.1 --- Introduction --- p.6
Chapter 2.1.1 --- Basic Theory --- p.7
Chapter 2.1.2 --- Amorphization --- p.9
Chapter 2.1.3 --- Amorphous Layer Regrowth --- p.10
Chapter 2.1.4 --- Point Defect Sources --- p.11
Chapter 2.1.5 --- Types of Extended Defects --- p.11
Chapter 2.2 --- Nature of Point Defects --- p.15
Chapter 2.2.1 --- Important Parameters --- p.15
Chapter 2.2.2 --- Vacancy Centers in Semiconductor --- p.16
Chapter 2.2.3 --- Self-interstitial in Silicon --- p.17
Chapter 2.2.4 --- Distribution of Excess Point Defects --- p.18
Chapter 2.2.5 --- Energy Level of Defect Species --- p.19
Chapter CHAPTER THREE --- EXPERIMENTAL METHOD --- p.21
Chapter 3.1 --- Experimental --- p.21
Chapter 3.2 --- Spreading Resistance Profiling --- p.25
Chapter CHAPTER FOUR --- MODELING OF SPREADING RESISTANCE PROFILES OF ION-IMPLANTED DAMAGE IN SILICON --- p.29
Chapter 4.1 --- Introduction --- p.29
Chapter 4.2 --- Basic equation --- p.30
Chapter 4.3 --- Formation of Model --- p.34
Chapter CHAPTER FIVE --- RESULTS AND DISCUSSION --- p.37
Chapter 5.1 --- Results --- p.37
Chapter 5.2 --- Discussion --- p.55
Chapter CHAPTER SIX --- CONCLUSION AND SUGGESTIONS OF FURTHER WORK --- p.58
Chapter 6.1 --- Conclusion --- p.58
Chapter 6.2 --- Suggestions of further work --- p.59
APPENDIX A --- p.60
APPENDIX B
SPREADING RESISTIVITY PROFILES --- p.62
REFERENCE --- p.93

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, June, 2013
Diamond with its outstanding and unique physical properties offers the opportunity to be used as semiconductor material in future device technologies. Promising ap- plications are, among others, high speed and high-power electronic devices working under extreme conditions, such as high temperature and harsh chemical environments. With respect to electronic applications, a controlled doping of the material is neces- sary which is preferably done by ion implantation. The ion implantation technique allows incorporation of foreign atoms at de¯ned depths and with controlled spatial distribution which is not achievable with other methods. However, the ion implanta- tion process is always connected with the formation of defects which compensate and trap charge carriers thus degrading the electrical behaviour. It is therefore essential to understand the nature of defects produced under various implantation conditions. In this respect, this study involves the investigation of the nature of the radiation damage produced during the multi-implantation of carbon ions in synthetic high- pressure, high-temperature (HPHT) type Ib diamond spread over a range of energies from 50 to 150 keV and °uences, using the cold-implantation-rapid-annealing (CIRA) routine. Single energy implantation of carbon ions in synthetic HPHT (type Ib), at room temperature, was also performed. Both ion milling and FIB (Focused Ion Beam) milling were used to prepare thin specimen for transmission electron micro- scope (TEM) analysis. The unimplanted, implanted and annealed samples were characterized using trans- mission electron microscopy based techniques and Raman spectroscopy. ii iii In unimplanted type Ia natural diamond, a high density of platelets, exhibiting the typical contrast of both edge-on and inclined platelets on f100g planes was found. As-implanted HPHT type Ib diamond, implanted with single energy of 150 keV car- bon ions and °uence of 7£1015 ions cm¡2 revealed an amorphous diamond layer of about 80 nm in thickness while, for low °uence implantations, the damaged diamond retained its crystallinity after annealing at 1600 K. In addition, damaged diamond transformed into disordered carbon comprising regions with bent (002) graphitic fringes and regions of amorphous carbon when high °uence, i.e., one above the amor- phization/graphitisation threshold were used followed by rapid thermal annealing at 1600 K. Furthermore, the interface between the implanted and annealed layer and the diamond substrate at the end of the range, showed diamond crystallites, inter- spersed between regions of amorphous carbon and partially graphitized carbon. This indicates that solid phase epitaxial recrystallization regrowth in diamond does not occur.

Wurtzite GaN epilayers grown by metal organic chemical vapor deposition on sapphire substrates were subsequently ion implanted with Er to a dose of 5×10¹⁵ cm⁻². The implanted samples were annealed in nitrogen atmosphere at different temperatures to facilitate recovery from implantation related damage. In this paper we report the annealing behavior of Erbium implanted GaN by using micro Raman spectroscopy and optimized annealing condition. We have observed almost full damage recovery of the crystalline quality of Er implanted GaN after annealing at 1000°C for 2 minute. This observation is further confirmed by using AFM images.
Singapore-MIT Alliance (SMA)

博士
國立交通大學
電子工程系
90
This dissertation addresses the investigation and control of implantation damage induced anomalous diffusion in CMOS device design. First, interface induced boron uphill diffusion was found to play a major role in determining the junction depth of S/D extensions in a pMOSFET. The effects of the boron up-hill diffusion during low temperature thermal cycles were investigated in ultra-low energy BF2 implanted pMOS devices. Results of secondary ion mass spectrometry (SIMS) analysis show that boron interface pile-up is very important in S/D extension engineering. Short channel effects and Idsat-Ioff characteristics in pMOSFETs can be significantly improved by utilizing the up-hill diffusion. Transient enhanced diffusion (TED) of boron is found to be unimportant due to ultra-low implant energy. Attempts to reduce TED by inclusion of extra RTA are shown to be detrimental to device characteristics. Dependence of the boron up-hill diffusion on temperature was explored. It was observed that the uphill diffusion occurs only in a certain range of temperature. Low temperature process (<600C) is deleterious to boron ultra-shallow junction formation. Instead, relatively high temperature process, 700°C, is necessary to take maximum advantage of the uphill diffusion effect. Next, we propose a novel process whereby Antimony Assisted Arsenic Source/Drain Extension (A3 SDE) is employed to realize a steep and retrograde indium pocket profile for sub-0.1mm nMOSFETs. By engineering the defect distributions in the amorphous layer created by indium implant, this new process improves 8% current drive while maintaining the same Ioff. It reduces nMOS diode leakage by two orders of magnitude and sidewall junction capacitance near the gate by 14%. Reliability assessment of devices fabricated by the A3 SDE process reveals significant improvement in hot carrier effects and no observable degradation of gate oxide integrity. Finally, Optimization of a LDD doping profile to enhance hot carrier resistance in 3.3V input/output CMOS devices has been performed by utilizing phosphorus transient enhanced diffusion (TED). Hot carrier effects in hybrid arsenic/phosphorus LDD nMOSFETs with and without TED are characterized comprehensively. Our result shows that the substrate current in a nMOSFET with phosphorus TED can be substantially reduced, as compared to the one without TED. The reason is that the TED effect can yield a more graded n- LDD doping profile and thus a smaller lateral electric field. Further improvement of hot carrier reliability can be achieved by optimizing arsenic implant energy. Secondary ion mass spectrometry analysis for TED effect and two-dimensional device simulation for electric field and current flow distributions have been conducted. The phosphorus TED effects on transistor driving current and off-state leakage current are also investigated.

Group-III-nitride semiconductors (GaN, InGaN, and AlGaN) are important for the fabrication of a range of optoelectronic devices (such as blue-green light emitting diodes, laser diodes, and UV detectors) as well as devices for high-temperature/high-power electronics. In the fabrication of these devices, ion bombardment represents a very attractive technological tool. However, a successful application of ion implantation depends on an understanding of the effects of radiation damage. Hence, this thesis explores a number of fundamental aspects of radiation effects in wurtzite III-nitrides. Emphasis is given to an understanding of (i) the evolution of defect structures in III-nitrides during ion irradiation and (ii) the influence of ion bombardment on structural, mechanical, optical, and electrical properties of these materials. ¶ ... ¶ The work presented in this thesis has resulted in the identification and understanding of a number of both fundamental and technologically important ion-beam processes in III-nitrides. Most of the phenomena investigated are related to the nature and effects of implantation damage, such as lattice amorphization, formation of planar defects, preferential surface disordering, porosity, decomposition, and quenching of CL. These effects are often technologically undesirable, and the work of this thesis has indicated, in some cases, how such effects can be minimized or controlled. However, the thesis has also investigated one example where irradiation-produced defects can be successfully applied for a technological benefit, namely for electrical isolation of GaN-based devices. Finally, results of this thesis will clearly stimulate further research both to probe some of the mechanisms for unusual ion-induced effects and also to develop processes to avoid or repair unwanted lattice damage produced by ion bombardment.

Pyrochlore-type oxides (A2B2O7) and glass-ceramic composites have been investigated for nuclear waste sequestration applications due to the remarkable compositional diversity and structural flexibility of these materials. These properties can enhance the incorporation of radioactive waste elements and resistance to radiation induced structural damage. Radiation induced structural damage can be simulated by bombarding materials using high-energy heavy ions. The study has shown how the metal-oxygen bond covalency, cationic radii ratio (rA/rB), and oxygen vacancies of pyrochlore type oxides affect the resistance of these materials to radiation induced damage. RE2Ti2O7 (RE=La–Lu), Yb1.85Ca0.15Ti2O7-δ, Yb2Ti1.85Fe0.15O7-δ, and Gd2Ti2-xSnxO7 were synthesized by the ceramic method and investigated by X-ray absorption near edge spectroscopy (XANES), which allows for the study of the effect of elemental substitution on the electronic structure of materials. Surface sensitive glancing angle and total electron yield XANES (GA/TEY XANES) spectra have been used to study the damaged surface of the materials, as the high energy ions can only implant in the near-surface region (~ 450 nm) of the pellets. These measurements have allowed for an investigation of how the local structure of the materials changed after ion implantation and discussed in terms of coordination number and bonding environment. After investigating the ceramic materials, the glass-ceramic composite materials containing Gd2Ti2O7 pyrochlore type crystallites in a (borosilicate- and Fe-Al-borosilicate) glass were investigated. These glass-ceramic materials were synthesized and analyzed by backscattered electron (BSE) images and XANES spectra. The study has shown how the Gd2Ti2O7 crystallites interact within a glass matrix depending on glass composition, pyrochlore loading, and annealing temperature. Further, the GA-XANES spectra from these materials have shown that the glass ceramic composite materials show a similar response to ion implantation as pure ceramics (i.e., Gd2Ti2O7). All of these studies and techniques could provide a better understanding of how to develop and design materials for nuclear waste sequestration applications.

In der vorliegenden Arbeit wird erstmals das QQDS-Magnetspektrometer für die höchstauflösende Ionenstrahlanalytik leichter Elemente am Helmholtz-Zentrum Dresden-Rossendorf umfassend vorgestellt. Zusätzlich werden sowohl alle auf die Analytik Einfluss nehmenden Parameter untersucht als auch Methoden und Modelle vorgestellt, wie deren Einfluss vermieden oder rechnerisch kompensiert werden kann. Die Schwerpunkte dieser Arbeit gliedern sich in fünf Bereiche. Der Erste ist der Aufbau und die Inbetriebnahme des QQDS-Magnetspektrometers, der zugehörige Streukammer mit allen Peripheriegeräten und des eigens für die höchstauflösende elastische Rückstoßanalyse entwickelten Detektors. Sowohl das umgebaute Spektrometer als auch der im Rahmen dieser Arbeit gebaute Detektor wurden speziell an experimentelle Bedingungen für die höchstauflösende Ionenstrahlanalytik leichter Elemente angepasst und erstmalig auf einen routinemäßigen Einsatz hin getestet. Der Detektor besteht aus zwei Komponenten. Zum einen befindet sich am hinteren Ende des Detektors eine Bragg-Ionisationskammer, die zur Teilchenidentifikation genutzt wird. Zum anderen dient ein Proportionalzähler, der eine Hochwiderstandsanode besitzt und direkt hinter dem Eintrittsfenster montiert ist, zur Teilchenpositionsbestimmung im Detektor. Die folgenden zwei Schwerpunkte beinhalten grundlegende Untersuchungen zur Ionen-Festkörper-Wechselwirkung. Durch die Verwendung eines Magnetspektrometers ist die Messung der Ladungszustandsverteilung der herausgestreuten Teilchen direkt nach einem binären Stoß sowohl möglich als auch für die Analyse notwendig. Aus diesem Grund werden zum einen die Ladungszustände gemessen und zum anderen mit existierenden Modellen verglichen. Außerdem wird ein eigens entwickeltes Modell vorgestellt und erstmals im Rahmen dieser Arbeit angewendet, welches den ladungszustandsabhängigen Energieverlust bei der Tiefenprofilierung berücksichtigt. Es wird gezeigt, dass ohne die Anwendung dieses Modells die Tiefenprofile nicht mit den quantitativen Messungen mittels konventioneller Ionenstrahlanalytikmethoden und mit der Dickenmessung mittels Transmissionselektronenmikroskopie übereinstimmen, und damit falsche Werte liefern würden. Der zweite für die Thematik wesentliche Aspekt der Ionen-Festkörper-Wechselwirkung, sind die Probenschäden und -modifikationen, die während einer Schwerionen-bestrahlung auftreten. Dabei wird gezeigt, dass bei den hier verwendeten Energien sowohl elektronisches Sputtern als auch elektronisch verursachtes Grenzflächendurchmischen eintreten. Das elektronische Sputtern kann durch geeignete Strahlparameter für die meisten Proben ausreichend minimiert werden. Dagegen ist der Einfluss der Grenzflächendurchmischung meist signifikant, so dass dieser analysiert und in der Auswertung berücksichtigt werden muss. Schlussfolgernd aus diesen Untersuchungen ergibt sich für die höchstauflösende Ionenstrahlanalytik leichter Elemente am Rossendorfer 5-MV Tandembeschleuniger, dass die geeignetsten Primärionen Chlor mit einer Energie von 20 MeV sind. In Einzelfällen, wie zum Beispiel der Analyse von Bor, muss die Energie jedoch auf 6,5 MeV reduziert werden, um das elektronische Sputtern bei der notwendigen Fluenz unterhalb der Nachweisgrenze zu halten. Der vierte Schwerpunkt ist die Untersuchung von sowohl qualitativen als auch quantitativen Einflüssen bestimmter Probeneigenschaften, wie beispielsweise Oberflächenrauheit, auf die Form des gemessenen Energiespektrums beziehungsweise auf das analysierte Tiefenprofil. Die Kenntnis der Rauheit einer Probe an der Oberfläche und an den Grenzflächen ist für die Analytik unabdingbar. Als Resultat der genannten Betrachtungen werden die Einflüsse von Probeneigenschaften und Ionen-Festkörper-Wechselwirkungen auf die Energie- beziehungsweise Tiefenauflösung des Gesamtsystems beschrieben, berechnet und mit der konventionellen Ionenstrahlanalytik verglichen. Die Möglichkeiten der höchstauflösenden Ionenstrahlanalytik werden zudem mit den von anderen Gruppen veröffentlichten Komplementärmethoden gegenübergestellt. Der fünfte und letzte Schwerpunkt ist die Analytik leichter Elemente in ultradünnen Schichten unter Berücksichtigung aller in dieser Arbeit vorgestellten Modelle, wie die Reduzierung des Einflusses von Strahlschäden oder die Quantifizierung der Elemente im dynamischen Ladungszustandsnichtgleichgewicht. Es wird die Tiefenprofilierung von Mehrschichtsystemen, bestehend aus SiO2-Si3N4Ox-SiO2 auf Silizium, von Ultra-Shallow-Junction Bor-Implantationsprofilen und von ultradünnen Oxidschichten, wie zum Beispiel High-k-Materialien, demonstriert.
In this thesis the QQDS magnetic spectrometer that is used for high resolution ion beam analysis (IBA) of light elements at the Helmholtz-Zentrum Dresden-Rossendorf is presented for the first time. In addition all parameters are investigated that influence the analysis. Methods and models are presented with which the effects can be minimised or calculated. There are five focal points of this thesis. The first point is the construction and commissioning of the QQDS magnetic spectrometer, the corresponding scattering chamber with all the peripherals and the detector, which is specially developed for high resolution elastic recoil detection. Both the reconstructed spectrometer and the detector were adapted to the specific experimental conditions needed for high-resolution Ion beam analysis of light elements and tested for routine practice. The detector consists of two compo-nents. At the back end of the detector a Bragg ionization chamber is mounted, which is used for the particle identification. At the front end, directly behind the entrance window a proportional counter is mounted. This proportional counter includes a high-resistance anode. Thus, the position of the particles is determined in the detector. The following two points concern fundamental studies of ion-solid interaction. By using a magnetic spectrometer the charge state distribution of the particles scattered from the sample after a binary collision is both possible and necessary for the analysis. For this reason the charge states are measured and compared with existing models. In addition, a model is developed that takes into account the charge state dependent energy loss. It is shown that without the application of this model the depth profiles do not correspond with the quantitative measurements by conventional IBA methods and with the thickness obtained by transmission electron microscopy. The second fundamental ion-solid interaction is the damage and the modification of the sample that occurs during heavy ion irradiation. It is shown that the used energies occur both electronic sputtering and electronically induced interface mixing. Electronic sputtering is minimised by using optimised beam parameters. For most samples the effect is below the detection limit for a fluence sufficient for the analysis. However, the influence of interface mixing is so strong that it has to be included in the analysis of the layers of the depth profiles. It is concluded from these studies that at the Rossendorf 5 MV tandem accelerator chlorine ions with an energy of 20 MeV deliver the best results. In some cases, such as the analysis of boron, the energy must be reduced to 6.5 MeV in order to retain the electronic sputtering below the detection limit. The fourth focus is the study of the influence of specific sample properties, such as surface roughness, on the shape of a measured energy spectra and respectively on the analysed depth profile. It is shown that knowledge of the roughness of a sample at the surface and at the interfaces for the analysis is needed. In addition, the contribution parameters limiting the depth resolution are calculated and compared with the conventional ion beam analysis. Finally, a comparison is made between the high-resolution ion beam analysis and complementary methods published by other research groups. The fifth and last focus is the analysis of light elements in ultra thin layers. All models presented in this thesis to reduce the influence of beam damage are taken into account. The dynamic non-equilibrium charge state is also included for the quantification of elements. Depth profiling of multilayer systems is demonstrated for systems consisting of SiO2-Si3N4Ox-SiO2 on silicon, boron implantation profiles for ultra shallow junctions and ultra thin oxide layers, such as used as high-k materials.