A contribution to the implementation of ultraprecision rotations for multiaxial nanopositioning machines

Existing long range nanopositioning and nanomeasuring machines are based on three independent linear movements in three rectangular axes. This in combination with the specific nature of optical and mechanical sensors and tools limits the application of those machines in terms of addressable part geometries. State of the art multiaxial precision machines solve this problem but do not fulfil the requirements in positioning accuracy. This article contributes to the development of multiaxial machine structures allowing e.g. 5-axis operation while keeping the precision in the nanometre range. A parameter based dynamic evaluation system with quantifiable technological parameters is performed to identify general solution concepts. State of the art machines are evaluated based on this classification system in terms of the implementation of multi-axial movements. The evaluation system is further refined with comprehensive design catalogues and corresponding diagrams to support the selection of adequate substructures. First evaluations for the substructure in terms of a rotation axis for the probing system of a nanopositioning machine in its XZ-plane show the highest degree of fulfilment for basic structures considering a goniometer setup. After all, the knowledge gained is formed into general rules for the verification and optimization of constructive solutions for multiaxial nanopositioning machines

Development and implementation of a rotating nanoimprint lithography tool for orthogonal imprinting on edges of curved surfaces

Uniform molding and demolding of structures on highly curved surfaces through conformal contact is a crucial yet often-overlooked aspect of nanoimprint lithography (NIL). This study describes the development of a NIL tool and its integration into a nanopositioning and nanomeasuring machine to achieve high-precision orthogonal molding and demolding for soft ultraviolet-assisted NIL (soft UV-NIL). The process was implemented primarily on the edges of highly curved plano-convex substrates to demonstrate structure uniformity on the edges. High-resolution nanostructures of sub-200-nm lateral dimension and microstructures in the range of tens of microns were imprinted. However, the nanostructures on the edges of the large, curved substrates were difficult to characterize precisely. Therefore, microstructures were used to measure the structure fidelity and were characterized using profilometry, white light interferometry, and confocal laser scanning microscopy. Regardless of the restricted imaging capabilities at high inclinations for high-resolution nanostructures, the scanning electron microscope (SEM) imaging of the structures on top of the lens substrate and at an inclination of 45° was performed. The micro and nanostructures were successfully imprinted on the edges of the plano-convex lens at angles of 45°, 60°,and 90° from the center of rotation of the rotating NIL tool. The method enables precise imprinting at high inclinations, thereby presenting a different approach to soft UV-NIL on curved surfaces

Fundamental investigations in the design of five-axis nanopositioning machines for measurement and fabrication purposes

The majority of nanopositioning and nanomeasuring machines (NPMMs) are based on three independent linear movements in a Cartesian coordinate system. This in combination with the specific nature of sensors and tools limits the addressable part geometries. An enhancement of an NPMM is introduced by the implementation of rotational movements while keeping the precision in the nanometer range. For this purpose, a parameter-based dynamic evaluation system with quantifiable technological parameters has been set up and employed to identify and assess general solution concepts and adequate substructures. Evaluations taken show high potential for three linear movements of the object in combination with two angular movements of the tool. The influence of the additional rotation systems on the existing structure of NPMMs has been investigated further on. Test series on the repeatability of an NPMM enhanced by a chosen combination of a rotary stage and a goniometer setup are realized. As a result of these test series, the necessity of in situ position determination of the tool became very clear. The tool position is measured in situ in relation to a hemispherical reference mirror by three Fabry-Pérot interferometers. FEA optimization has been used to enhance the overall system structure with regard to reproducibility and long-term stability. Results have been experimentally investigated by use of a retroreflector as a tool and the various laser interferometers of the NPMM. The knowledge gained has been formed into general rules for the verification and optimization of design solutions for multiaxial nanopositioning machines

Measurement uncertainty analysis on a five-axis nano coordinate measuring machine NMM-5D following a vectorial approach

Dieser Beitrag zeigt ein Konzept für eine fünfachsige Nano-Koordinatenmessmaschine zur Messung auf stark gekrümmten asphärischen und frei geformten optischen Oberflächen in einem Messvolumen von 25mm × 25mm × 5mm mit einem maximal möglichen Neigungswinkel von bis zu 60° zur Hochachse und einer maximalen Rotation von 360° um die Hochachse. Dabei wird die Probe translatorisch bewegt und der Sensor in seiner Orientierung verändert. Unter Einhaltung des Abbe-Komparatorprinzips für alle Messachsen wird die Bewegungsabweichung des Sensors bei der Rotation durch ein in-situ-Referenzmesssystem erfasst. Dieses besteht aus drei kartesisch angeordneten Fabry-Pérot-Interferometern mit dem Ursprung im Antastpunktes des Sensors, die den Abstand zu einer hemisphärischen Referenzfläche messen. Die Messunsicherheitsbetrachtung des Gesamtsystems erfolgt nach dem guide to the expression of uncertainty in measurement in einem vektoriellen Ansatz und liefert unter konservativen Annahmen eine Unsicherheit des Antastpunktes von maximal 72 nm (k=1).In this paper a novel concept of an five axes nano coordinate measuring machine for the measurement on strongly curved aspheric and freeform optics is shown. Thereby the sample is moved translational in a measuring volume of 25mm×25mm×5mm and the sensor can be tilted up to an angle of 60° and it can be rotated up 360° around the z-axis. By strictly following the abbe comparator principle, the motion error that occurs during the sensor rotation is measured by an in-situ reference measuring system. It consists of three Fabry-Pérot-Interferometers whose measuring directions span a cartesian coordinate system with the origin in the sensors probing point. Those interferometers measure the distance to concentric arranged reference hemisphere. The measurement uncertainty is derived according to the Guide to the expression of uncertainty in measurement. A conservative estimation shows a maximum uncertainty of the probing point of 72 nm (k=1)

Tip- and laser-based 3D nanofabrication in extended macroscopic working areas

The field of optical lithography is subject to intense research and has gained enormous improvement. However, the effort necessary for creating structures at the size of 20 nm and below is considerable using conventional technologies. This effort and the resulting financial requirements can only be tackled by few global companies and thus a paradigm change for the semiconductor industry is conceivable: custom design and solutions for specific applications will dominate future development (Fritze in: Panning EM, Liddle JA (eds) Novel patterning technologies. International society for optics and photonics. SPIE, Bellingham, 2021. https://doi.org/10.1117/12.2593229). For this reason, new aspects arise for future lithography, which is why enormous effort has been directed to the development of alternative fabrication technologies. Yet, the technologies emerging from this process, which are promising for coping with the current resolution and accuracy challenges, are only demonstrated as a proof-of-concept on a lab scale of several square micrometers. Such scale is not adequate for the requirements of modern lithography; therefore, there is the need for new and alternative cross-scale solutions to further advance the possibilities of unconventional nanotechnologies. Similar challenges arise because of the technical progress in various other fields, realizing new and unique functionalities based on nanoscale effects, e.g., in nanophotonics, quantum computing, energy harvesting, and life sciences. Experimental platforms for basic research in the field of scale-spanning nanomeasuring and nanofabrication are necessary for these tasks, which are available at the Technische Universität Ilmenau in the form of nanopositioning and nanomeasuring (NPM) machines. With this equipment, the limits of technical structurability are explored for high-performance tip-based and laser-based processes for enabling real 3D nanofabrication with the highest precision in an adequate working range of several thousand cubic millimeters

Grundlegende Untersuchungen zum konstruktiven Aufbau von Fünfachs-Nanopositionier- und Nanomessmaschinen

Die vorliegende Arbeit beinhaltet Realisierungsmöglichkeiten des konstruktiven Aufbaus von Fünfachs-Nanopositionier-und Nanomessmaschinen für die Messung und Fabrikation makroskopischer Objekte mit Nanometerpräzision. Mit zusätzlichen rotatorischen Freiheiten wird die Limitierung etablierter, überwiegend kartesisch operierender Nanopositionier-und Nanomessmaschinen (NPMM) hinsichtlich der Adressierbarkeit stark gekrümmter Objektgeometrien überwunden. Es werden modular variierte Maschinenkonzepte im Hinblick auf die Realisierung mehrachsiger Bewegungen und unter der Voraussetzung der Erweiterbarkeit kartesischer NPMMs systematisch entwickelt und auf der Grundlage eines Klassifzierungssystems evaluiert. Ein hohes Potential zeigen Varianten mit drei unabhängigen linearen Bewegungen des Objektes in Kombination mit zwei unabhängigen Rotationen des Tools um einen gemeinsamen Momentanpol, der dauerhaft mit dem Arbeitspunkt des Tools (TCP) und dem Abbepunkt der kartesischen NPMM übereinstimmt. Insbesondere die Rotation des Tools um die Hochachse der NPMM mittels Drehtisch in Kombination mit einer Rotation in der horizontalen xy-Ebene unter Verwendung eines Goniometers zeigen einen hohen Erfüllungsgrad. Im Rahmen experimenteller Untersuchungen wird ein derartiger Aufbau innerhalb einer NPMM erprobt, der die Rotationen eines Tools mit einer Masse < 2 kg gewährleistet. Eine asymmetrische Anordnung des Goniometers entlang dessen Hauptdrehachse erlaubt den Einsatz von Tools, deren Gestalt das Arbeitsvolumen des Goniometers überschreitet. Es sind Rotationsbereiche des Tools von 360° um die Hochachse der NPMM und Neigungen zur Hochachse von 90° möglich. Die Integration ultrapräziser Rotationseinheiten in die NPMM erfolgt unter Zuhilfenahme finite Elemente gestützter Modellbildung und daraus abgeleiteter Strukturoptimierung der Koppelstellen. Unter Anwendung von Laserinterferometern in Kombination mit einem geeigneten Retroreflektor im TCP werden Einfüsse der zusätzlichen rotatorischen Positioniersysteme, wie Verformungen und Positionierwiederholbarkeiten, in der NPMM in situ gemessen. Wie beispielhaft mit der Anwendung eines entwickelten Nanoimprinttools gezeigt, erlauben die erreichten Positioniereigenschaften eine Adressierung und Bearbeitung dreidimensionaler Körper mit stark gekrümmter Oberfäche. Ein entwickelter neuartiger Aufbau der Gesamtstruktur, bei dem für die kombinierte Messung der Positionierabweichungen Fabry-Pérot-Interferometer zur Anwendung kommen, gewährleistet den Einbezug der Rotationen in den geschlossenen Regelkreis, wodurch die Mess-und Bearbeitungsgenauigkeit erhöht und die Prozesszeit verkürzt werden. Die Interferometer erfassen die Positionierabweichungen gegenüber einem halbkugelförmigen Konkavspiegel, der mit dem metrologischen Rahmen der NPMM direkt verbunden ist. Abschließend werden Konstruktionsrichtlinien für die Entwicklung von Fünfachs-Nanopositionier-und Nanomessmaschinen zusammengefasst.This thesis adresses the development of new concepts of the design of five-axis nanopositioning and nanomeasuring machines for the measurement and fabrication in macroscopic volumes while keeping the precision in the nanometer range. With additional rotations, the limitations of established, mainly Cartesian operating nanopositioning and nanomeasuring machines (NPMM) regarding the addressability of strongly curved object geometries are solved. Modularly varied machine concepts are systematically developed and evaluated on the basis of a classification system with regard to the realization of multi-axis movements and under the condition of the expandability of Cartesian NPMMs. A high potential is given by variants with three independent linear movements of the object in combination with two independent rotations of the tool around a common instantaneous centre, which permanently corresponds to the operating point of the tool (TCP) and the Abbe point of the Cartesian part of the NPMM. Especially the rotation of the tool around the vertical axis of the NPMM using a precision rotation stage in combination with a rotation in the horizontal xy-plane using a goniometer show a high degree of fulfillment. Within the scope of experimental investigations, a corresponding setup within a NPMM is investigated, which guarantees the rotations of a tool with a mass of < 2 kg. An asymmetrical arrangement of the goniometer along its main axis of rotation allows the use of tools whose geometry exceeds the working volume of the goniometer. Tool rotation ranges of 360° around the vertical axis of the NPMM and inclinations to the vertical axis of 90° are possible. The influence of the additional positioning systems on the existing structure of NPMMs are investigated and solutions for the optimization of the overall system with regard to reproducibility and longterm stability are developed. For this purpose, comprehensive FEA simulations are carried out and structural improvements are derived via topology optimizations. Using laser interferometers in combination with a suitable retroreflector in the TCP, influences of the additional rotary positioning systems, such as positioning repeatabilities, are measured in situ in the NPMM. As shown exemplarily with the application of a developed nanoimprint tool, the achieved positioning properties allow addressing and processing of three-dimensional objects normal to their strongly curved surface. A developed new type of overall structure, in which Fabry-Pérot interferometers are used for the combined measurement of positioning deviations, ensures that the rotations are included in the closed control loop, thus increasing the measurement and machining accuracy and reducing the operating time. The interferometers measure the positioning errors against a hemispherical concave mirror directly mounted to the metrological frame of the NPMM. After all, the knowledge gained is formed into general rules for the design of five-axis nanopositioning and nanomeasuring machines

Cell Orientation by a Microgrooved Substrate Can Be Predicted by Automatic Control Theory

Cells have the ability to measure and respond to extracellular signals like chemical molecules and topographical surface features by changing their orientation. Here, we examined the orientation of cultured human melanocytes exposed to grooved topographies. To predict the cells' orientation response, we describe the cell behavior with an automatic controller model. The predicted dependence of the cell response to height and spatial frequency of the grooves is obtained by considering the symmetry of the system (cell + substrate). One basic result is that the automatic controller responds to the square of the product of groove height and spatial frequency or to the aspect ratio for symmetric grooves. This theoretical prediction was verified by the experiments, in which melanocytes were exposed to microfabricated poly(dimethylsiloxane) substrates having parallel rectangular grooves of heights (h) between 25 and 200 nm and spatial frequencies (L) between 100 and 500 mm(−1). In addition, the model of the cellular automatic controller is extended to include the case of different guiding signals acting simultaneously