Rapid progress in several high-tech industries has significantly increased the need for dimensional micro- and nano-metrology. Structures to be measured are becoming more complex with smaller structure widths and higher aspect ratios in increasingly larger surface regions and potentially highly curved surfaces. Significant international effort can be seen to develop high-capacity measuring machines with nanometre precision in growing measuring ranges up to hundreds of millimetres. This paper begins with an outline of the requirements stemming from high-tech developments currently being done or expected in the future and discusses recent developments in the field of nanopositioning and nanomeasuring technology with respect to basic measurement approaches, laser interferometer systems. The large range of nanoprobe systems usable in nanomeasuring machines is discussed, such as optical focus sensors, white light interferometer microscopes, CCD camera microscopes using the depth from the focus method, tactile stylus probes, atomic force microscopes (AFMs) and 3D microprobes. The versatile properties of these sensors allow the machine to be used in many different metrological applications. The paper also introduces a multi-sensor approach using a microscope revolver. It concludes with an illustration of metrologically challenging measurements, e.g., scanning micro-structures of curved optical surfaces or performing AFM scans of very large regions with significant data volume.

In this article a new approach for the direct traceability of interferometric length measurements in nanopositioning- and measuring machines is presented. The concept is based on an optical frequency comb tied to a GPS disciplined oscillator. The frequency comb serves as a highly stable reference laser with traceable optical frequencies. By directly stabilizing the metrology lasers of a nanopositioning and -measuring machine to a single comb line a permanent link of the laser frequency to an atomic clock is created allowing direct traceability to the SI meter definition. The experimental conditions to provide traceability will be discussed. Furthermore, it is demonstrated how the long-term frequency stability of an individual comb line can be transferred onto the metrology lasers enhancing their stability by three orders of magnitude.

Nanopositioning and nanomeasuring machines (NPM-machines), developed at Technische Universität Ilmenau, have provided high-precision measurement and positioning of objects across ten decades, from 20 pm resolution up to 200 mm measuring range. They work on the basis of the error-minimal, extended six degrees of freedom Abbe-comparator principle, with high-precision fibre-coupled laser interferometers and optical or atomic force probes. These machines are suitable not only for measuring but also for positioning with an outstanding sub-nanometre performance. Measurements on precision step heights up to 5 mm show a repeatability of 20 pm. Consecutive step positioning of 80 pm can be demonstrated. With the new approach of an atomic clock-stabilized He–Ne-laser via a high-stable-frequency comb, we achieve a frequency stability of less than 300 Hz, respectively 0.6 ċ 10−12 relative frequency stability within 1 h at an integration time of 1 s. For the first time, we can demonstrate a direct, permanent and unbroken chain of traceability between the laser interferometric measurement within an NPM-machine and a GPS satellite-based atomic clock. This paper presents a closer insight into the scientific and metrological background as well as unrivalled measurement results, and discusses the great possibilities of this new technology.

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. 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.

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