Novel chromatic confocal differential interference contrast prototype. - In: Optical Measurement Systems for Industrial Inspection XI, (2019), S. 1105611-1-1105611-9
By combining classic differential interference contrast (DIC) with the chromatic confocal principle, we show that phaseshifting calibration can be avoided in DIC by using spectral information induced by the investigated sample. The created spectral fringe can be further used to unwrap the phase. This unwrapping is limited by the spectral resolution of the spectrometer. Therefore, the depth-difference around a single measurement point can be determined instantaneously. To reconstruct the depth profile, the integration of a depth-gradient is necessary. By combining the depth information of the chromatic confocal carrier signal with the differential depth information of the carried DIC signal, the accumulation of measurement uncertainty can be reduced. To our best knowledge, the proposed chromatic confocal differential interference contrast (CCDIC) is a novel profile reconstruction principle. To verify the feasibility of the CCDIC, a prototype probe with an adjustable shear and phase has been developed. Preliminary experiments achieve sub-micrometer depth resolution. A current challenge requiring further work is the stable unwrapping of the phase-difference by spectral frequencies. Keywords: chromatic confocal, differential interference contrast, unwrapping, industrial metrology
https://doi.org/10.1117/12.2527854
Model based laser focus scanning - the path towards improved lateral accuracy. - In: Modeling Aspects in Optical Metrology VII, (2019), S. 110570F-1-110570F-12
In principal, optical measurement methods suffer from physical limits related to finite wavelengths and diffraction. In laser focus scanning, vertical resolutions below 1 nm can be achieved while the lateral accuracy is more or less restricted by the diameter of the focused laser beam, i.e. values of half the wavelength can be reached in the best case. We present a model based approach having the potential to show a way out of this limitation. It is based on the rigorous modeling of the complete measurement device including sophisticated ray tracing in combination with Maxwell based modeling of the sample diffraction and scattering providing a simulated signal for an assumed sample profile. Furthermore, the sample profile is parametrized on the basis of a priori information. The simulated signal is then iteratively compared with the measured signal while updating the floating parameters of the model in order to improve the match between the two signals. Eventually, the improved sample profile obtained in this way is considered to represent the real sample profile as soon as a certain goodness of fit is achieved. On the other hand, the profile model has to be changed in case there is no satisfying fit. In this way, the lateral accuracy can be increased considerably. Edge detection errors below a few tens nanometer or even below 10 nm become possible while measuring with visible light. This is demonstrated by first comparisons of modeled and measured signals and validation by alternative metrology techniques.
https://doi.org/10.1117/12.2525319
Micro- and nanofabrication technologies using the nanopositioning and nanomeasuring machines. - In: Optical Measurement Systems for Industrial Inspection XI, (2019), S. 1105637-1-1105637-13
To keep up with Moore's law in future, the critical dimensions of device features must further decrease in size. Thus, the nano-electronics and nano-optics manufacturing is based on the ongoing development of the lithography and encompasses also some unconventional methods. In this context, we use the Nanopositioning and Nanomeasuring Machine (NPMM) to generate features in resist layers by means of Direct Laser Writing (DLW),1 Field Emission Scanning Probe Lithography (FE-SPL)2 and Soft UV-Nanoimprint Lithography (Soft UV-NIL)3 with highest accuracy. The NPMM was collaboratively developed by TU Ilmenau and SIOS Meßtechnik GmbH.4 The tool provides a large positioning volume of 25 mm × 25 mm × 5 mm with a positioning resolution of 0.1 nm and a repeatability of less than 0.3 nm over the full range. Previously a single electron transistor (SET) working at room temperature generated by FE-SPL has been demonstrated.5 However, the throughput is limited because of the serial writing scheme making Tennant's law (At R5 ) valid.6 Here, At is the areal throughput and R the lithographic resolution. Thus, patterning of the whole NPMM positioning area by FE-SPL is very time consuming. In order to address this problem, different strategies and/or combinations are conceivable. In this work a so-called Mix-and-Match lithography is conducted. A fast generation of structures in the sub-micron range is possible by means of DLW. By this, features such as electrical wires, contact patches for bonding or labels are generated in resist. Subsequently, we use FE-SPL in order to define the actual nano-scaled features for quantum or single electron devices. In combination, DLW and FE-SPL are maskless lithography strategies, hence, offering completely novel opportunities for rapid nanoscale prototyping of largescale resist patterns. An explanation of this technique is given in a previous publication.7 Furthermore, after reactive ion etching, the sample can be used as template for Soft UV-NIL, thus resulting in a high-throughput process chain for future quantum and/or single electron devices.
https://doi.org/10.1117/12.2528136
Temperature dependence of dynamic parameters of contact thermometers. - In: Sensors, ISSN 1424-8220, Bd. 19 (2019), 10, 2299, insges. 9 S.
https://doi.org/10.3390/s19102299
Tip-based nano-manufacturing and -metrology. - In: Journal of vacuum science & technology, ISSN 2166-2754, Bd. 37 (2019), 3, S. 030803, insges. 9 S.
Sub-5 nm lithography and metrology are the key technologies for more CMOS and beyond CMOS nanoelectronics. To keep up with scaling down of nanoelectronic components, novel instrumentation for nanometer precise placement, overlay alignment, and measurement are essential to enable fabrication of next generation nanoelectronic systems. In particular, scanning probe microscopy (SPM) based methods for surface modification and measurement are the emerging techniques for producing and testing of sub-5 nm features. In this article, the authors demonstrate nanoscale lithography and coordinate metrology technologies, both being based on SPM methodology. Scanning probes with a piezoresistive deflection read-out and an integrated deflection actuator, later on referred to as the active piezoresistive cantilevers, were used for lithography employing field emission patterning. They were also integrated with the so-called nanomeasuring machine (NPM) andused for surface imaging, which made it possible to measure the structure dimensions in the 25 × 25 × 5 mm^3 space with 0.1 nm resolution and great accuracy. The basic NPM concept relies on a unique arrangement, enabling the so-called Abbe error-free measurements in all axes over the total scan range. The combination of the active piezoresistive cantilevers and NPM technologies makes it possible to store the exact location on the investigated surface, which can be found again with an accuracy of less than 2.5 nm. This system is also predestinated for the critical dimension, quality, and overlay control.
https://doi.org/10.1116/1.5083044
Laser-microfabrication with accurate positioning and metrological traceability. - In: Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XII, (2019), Seite 109300L-1-109300L-8
https://doi.org/10.1117/12.2508248
A combined laser scanning and DLW tool for measuring and fabrication tasks with NPMM. - In: Advanced Fabrication Technologies for Micro/Nano Optics and Photonics XII, (2019), S. 1093017-1-1093017-6
In view of the increasing demands on precision optics, microelectronics and precision mechanics nanoscale structuring processes are of great interest. It is becoming more and more important to apply a large number of structures that are as small as possible to ever larger areas with high reliability and to increase the number of structures per area element (packing density). The straightness and uniformity of these structures, as well as the positioning accuracy during the fabrication of such narrow lines and points are at the center of the increase of the packing density. A further decisive role is played by the development of suitable sensors and tools for the production and measurement of these structures. The development and the combination of a new laser based probe for the measurement and a direct laser writing (DLW) tool for the creation of sub-micro structures forms the core of this topic. The new sensor is based on a confocal measuring principle. A fiber coupling is used to avoid thermal influences. At the same time, the fiber end itself serves as a confocal pinhole. For the process tool, comprehensive investigations of laser and resist parameters are necessary. The first results are shown. These two parts are investigated separately and combined at the end of the work. In order to achieve the necessary positioning accuracy, the tool is integrated into the Nanopositioning and Measurement Machine (NPMM).
https://doi.org/10.1117/12.2508263
Torsion balance-based system for high-precision force measurement in horizontal plane: part II. Static and dynamic improvement. - In: Measurement science and technology, ISSN 1361-6501, Volume 30 (2019), 5, 055104, Seite 1-9
https://doi.org/10.1088/1361-6501/ab05aa
Nanofabrication in extended areas on the basis of nanopositioning and nanomeasuring machines. - In: Novel Patterning Technologies for Semiconductors, MEMS/NEMS, and MOEMS 2019, (2019), S. 109580P-1-109580P-9
Alternative lithography approaches, especially pattering technologies are in advance since several years. Every day new, more or less high localized, AFM-tip based structuring methods as well as new optical and e-beam methods become acquainted. Most of them are sequential single-point procedures. The local interaction reaches from 150 nm up to sub-10 nm. Especially tip based methods are developed on the basis of atomic force microscopes AFM. Therefore, the ranges, which can be structured, are only in the range of 2 [my]m x 2 [my]m up to 100 [my]m x 100 [my]m. In most cases it is not known or not verified if those new tip based techniques are suitable for larger ranges and areas. Even the stages and control algorithms of AFM's are not optimized for defined, high dynamic and as well high stable scanning trajectories in the nanometre respectively in the sub-nanometre level.
https://doi.org/10.1117/12.2514009
Integrated soft UV-nanoimprint lithography in a nanopositioning and nanomeasuring machine for accurate positioning of stamp to substrate. - In: Novel Patterning Technologies for Semiconductors, MEMS/NEMS, and MOEMS 2019, (2019), S. 1095819-1-1095819-7
https://doi.org/10.1117/12.2514832