A multiscale systems approach to microelectronic processes

Abstract This paper describes applications of molecular simulation to microelectronics processes and the subsequent development of techniques for multiscale simulation and multiscale systems engineering. The progression of the applications of simulation in the semiconductor industry from macroscopic to molecular to multiscale is reviewed. Multiscale systems are presented as an approach that incorporates molecular and multiscale simulation to design processes that control events at the molecular scale while simultaneously optimizing all length scales from the molecular to the macroscopic. It is discussed how design and control problems in microelectronics and nanotechnology, including the targeted design of processes and products at the molecular scale, can be addressed using the multiscale systems tools. This provides a framework for addressing the "grand challenge" of nanotechnology: how to move nanoscale science and technology from art to an engineering discipline

Advanced micro and nano fabrications for engineering applications

This document is a compilation of my selected research publications in micro and nano fabrications. The papers are largely arranged in chronological order to show the development of research interests. The research works are grouped into three sections. Section one consists of 34 research papers on micro fabrication in various materials. The research was motivated by the development of a finger nail sized micro engine as explained in Papers 1 and 2. Section two of the document includes some research activities and achievements on nanocomposite materials embedded in metallic and ceramic matrices. Section 3 includes the papers to reflect the research in developing nanostructure fabrication processes. The research contained in this DSc submission shows a continuous exploration and development of novel micro/nano fabrication processes. Although the submission covers research activities spanning 15 years, from 2000 to 2015, many of the research results represent the top technology of the time. They have contributed to the ever progressing manufacturing capability of the world. The research has encompassed both theoretical and experimental studies, contributing to the understanding of the processes and materials involved

Modélisation des effets de déplacements atomiques induits par irradiation dans les matériaux pour la microélectronique

Les domaines de l'ingénierie spatiale et nucléaire requièrent le développement et l'utilisation de composants opto et microélectroniques spécifiques. Or, pour des applications dans les domaines cités, les composants sont immergés dans des environnements fortement radiatifs et sont donc soumis à des flux importants de particules énergétiques qui dégradent leur fonctionnement en induisant la formation de charges libres par ionisation de la matière ainsi que la création de défauts cristallins par déplacements atomiques. Ce dernier mécanisme est le sujet de la présente thèse. D'un point de vue technologique, les effets des déplacements atomiques sont assez bien connus. Par exemple, on sait qu'ils sont responsables d'une forte augmentation du courant d'obscurité mesuré dans les capteurs d'images, ou de la perte de puissance maximale délivrée par les cellules photovoltaïques. En revanche, les origines physiques fondamentales des effets mesurés technologiquement sont encore sujettes à débat. Les difficultés rencontrées quant à l'établissement du lien entre la physique et les effets observés dans les technologies résident en partie dans la durée extrêmement courte des temps caractéristiques (de la femtoseconde à la picoseconde pour une collision atomique par exemple) des phénomènes dynamiques en jeu dans les premiers instants de la dégradation d'un composant, rendant impossible ou extrêmement compliquée la réalisation d'expériences. C'est la raison pour laquelle, dans cette thèse, nous avons recours à la simulation numérique afin de mieux comprendre le lien entre phénomènes physiques et effets observés et ainsi prédire la réponse des matériaux utilisés en microélectronique aux effets de déplacements atomiques. Une chaîne de simulation multi-échelle, décrite dans ce manuscrit, a été développée en ce sens, permettant de simuler tout le processus de déplacements atomiques : l'interaction particule-matière en Monte Carlo, la propagation de la cascade de collisions dans la matière en Dynamique Moléculaire, la guérison des structures endommagées en Monte Carlo-cinétique et enfin la caractérisation ab initio de l'activité électronique des défauts suspectés comme responsables de la dégradation de composants. Toutes les étapes, excepté la dernière, ont été adressées dans cette thèse. Plus spécifiquement, nous nous sommes appliqués à améliorer la seconde étape de Dynamique Moléculaire en insistant sur le caractère stochastique des cascades de collisions et sur l'inclusion des effets électroniques. En particulier sur ce dernier aspect, une méthode basée sur des calculs ab initio de Théorie de la Fonctionnelle de la Densité Dépendante du Temps est utilisée. Les résultats des études effectuées dans le but d'améliorer l'étape de Dynamique Moléculaire sont décrits dans la thèse. De plus, les trois premières étapes de la chaîne de simulation sont appliquées à Si, Ge et aux alliages Si-Ge, et les résultats obtenus présentés dans le manuscrit.The development and usage of dedicated opto and microelectronic devices is an essential aspect of space and nuclear research and industries. However, in space and nuclear environments, devices are subject to intense flux of energetic particles jeopardizing their correct working by inducing the formation of free charges via ionization of materials as well as creation of crystalline defects following atomic displacements. The latter mechanism is the subject of the present PhD thesis. Atomic displacements are quite well known from a technological point of view. For example, it is acknowledged they are responsible for the drastic increase of dark current observed in image sensors, or for the loss of maximum output power of solar cells. Nonetheless, the fundamental physical origins of experimentally measured effects are still subject to debate. The difficulties encountered in the establishment of a clear link between the effects observed in technologies and the fundamental mechanisms are partly due to the very short (of the order of the femtosecond to the picosecond for an atomic collision for example) characteristic timescales of the dynamic process at stake. Indeed, experiments cannot cover dynamic process of so small characteristic times. This is the reason why, in this PhD thesis, we resort to numerical modelling to understand the links between basic physical mechanisms and deleterious effects witnessed in technologies and thus predict the response to atomic displacements effects of materials used in microelectronic applications. Aiming at this ultimate purpose, a multiscale simulation approach has been developed, allowing simulating the entire process of atomic displacements: particle-matter interactions with Monte Carlo techniques, collision cascades propagation using Molecular Dynamics, healing of the damaged structures with a kinetic- Monte Carlo code and finally the electronic characterization of defects thought to be responsible for devices degradation with ab initio methods. All the mentioned steps of this approach, except the last one, have been addressed in this thesis. In more details, lots of efforts have been undertaken to improve the models and methodologies employed in the second molecular dynamics step, regarding the stochastic aspects of cascades as well as the inclusion of electronic effects. Concerning this last aspect, a method based on ab initio Time-Dependent Density Function Theory calculations of electronic stopping power is employed. The results of the studies carried out with the objective of improving the second step of Molecular Dynamics are presented in this thesis. In addition, the three first steps of the global simulation approach are applied to Si, Ge and Si-Ge alloys, and obtained results are presented and discussed in the manuscript

Modeling and multiresolution characterization of micro/nano surface for novel tailored nanostructures

Nanofabrication is state of the art technology. Various chemical, mechanical, biochemical and semiconductor products have characteristics controlled by the nanostructures of the surface and interphase. Surface microscopic imaging is generally used to capture different surface features. By properly analyzing the surface image, valuable information regarding manufacturing process and product performance can be extracted. While microscopy measurements can offer very accurate qualitative information about surface features, for many applications, it is critical to obtain a quantitative description of the surface morphology. Various statistical features can be used to characterize the surface in quantitative way. Such an analysis can be done by the multi-resolution capabilities of wavelet transforms (WT). A multi-scale molecular simulation can help to investigate the physical and chemical mechanism in manufacturing process. Multiresolution characterization was performed on the model structure to compare with image analysis. In our research, we have used a soft polymeric surface used in microfabrication application and a hard surface used for catalysis, and applied multiresolution characterization for surface feature extraction and multiscale modeling for optimizing system variables to get desired surface characteristics. In microfabrication, the efficiency of the product reduced by line-edge roughness (LER) created on the polymer surface. Off-line LER characterization is usually based on the top-down SEM image. We have shown a wavelet based segmentation method for edge searching region. There was no external decision involved in the wavelet based edge detection and characterization. Ab-initio atomistic based simulations are generally used for polymer material design in atomic scale. For mesoscale modeling we use the coarse graining of the molecules and use the Flory-Huggins mean field interaction parameters of the clusters of atoms or molecules obtained from ab-initio simulations. In our research we have used coarse grained lattice based important sampling Monte Carlo (MC) and kinetic Monte Carlo (kMC) methods for mesoscale simulation. We have identified the phase separation by spinodal decomposition resulting in the formation of LER. The kinetics of the process is found and the process variables are identified that can reduce the roughness. Surface of a transition metal have been analyzed in a similar way for enhanced catalytic performance

Towards Bio-impedance Based Labs: A Review

In this article, some of the main contributions to BI (Bio-Impedance) parameter-based systems for medical, biological and industrial fields, oriented to develop micro laboratory systems are summarized. These small systems are enabled by the development of new measurement techniques and systems (labs), based on the impedance as biomarker. The electrical properties of the life mater allow the straightforward, low cost and usually non-invasive measurement methods to define its status or value, with the possibility to know its time evolution. This work proposes a review of bio-impedance based methods being employed to develop new LoC (Lab-on-a-Chips) systems, and some open problems identified as main research challenges, such as, the accuracy limits of measurements techniques, the role of the microelectrode-biological impedance modeling in measurements and system portability specifications demanded for many applications.Spanish founded Project: TEC 2013-46242-C3-1-P: Integrated Microsystem for Cell Culture AssaysFEDE

White paper on the future of plasma science and technology in plastics and textiles

This is the peer reviewed version of the following article: “Uros, C., Walsh, J., Cernák, M., Labay, C., Canal, J.M., Canal, C. (2019) White paper on the future of plasma science and technology in plastics and textiles. Plasma processes and polymers, 16 1 which has been published in final form at [doi: 10.1002/ppap.201700228]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."This white paper considers the future of plasma science and technology related to the manufacturing and modifications of plastics and textiles, summarizing existing efforts and the current state‐of‐art for major topics related to plasma processing techniques. It draws on the frontier of plasma technologies in order to see beyond and identify the grand challenges which we face in the following 5–10 years. To progress and move the frontier forward, the paper highlights the major enabling technologies and topics related to the design of surfaces, coatings and materials with non‐equilibrium plasmas. The aim is to progress the field of plastics and textile production using advanced plasma processing as the key enabling technology which is environmentally friendly, cost efficient, and offers high‐speed processingPeer ReviewedPostprint (author's final draft