Niko Stephan Münzenrieder

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Münzenrieder

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Niko Stephan

ORCID

0000-0003-4653-5927

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Publications1 - 10 of 13

Mechanical and Electrical Design Strategies for Flexible InGaZnO Circuits
Cantarella, Giuseppe; Münzenrieder, Niko Stephan; Petti, Luisa; et al. (2021)
Proceedings of 28th International Conference on Mixed Design of Integrated Circuits and Systems (MIXDES 2021)
Thin-film transistors (TFTs) and circuits based on oxide semiconductors fabricated on flexible plastic foils and stretchable substrates are reported. Reliable fabrication protocols, using InGaZnO as n-type semiconductor, in combination with different design strategies, aiming at the improvement of both the electrical performance and the mechanical stability of such electronics, are discussed. First, simulation models are used to guide the fabrication of operational amplifiers and logic circuits on flexible polyimide foil, using an additional third metal layer for the interconnections. Thanks to the reduced parasitic resistances and capacitances, the resulting circuits have yielded improved electrical performances with respect to a two-metals architecture. In particular, an increase of 5.7% of the Gain-Bandwidth-Product (GBWP) for operational amplifiers, and an average reduction of 22% of the rise times, fall times and propagation delays for digital circuits, were achieved. In parallel, Finite-Element Modeling (FEM) has supported the design of engineered stretchable substrates shaped with pillar (or mesa) structures. The reduction of the strain experienced by the electronics, located on the mesa surfaces, during stretching, bending, and twisting, resulted in highly flexible digital circuits with functionality up to 20% elongation.
Wafer-scale design of lightweight and transparent electronics that wraps around hairs
Salvatore, Giovanni A.; Münzenrieder, Niko Stephan; Kinkeldei, Thomas; et al. (2014)
Nature Communications
Mechanically flexible vertically integrated a-IGZO thin-film transistors with 500 nm channel length fabricated on free standing plastic foil
Petti, Luisa; Aguirre, Paulina; Münzenrieder, Niko Stephan; et al. (2013)
2013 IEEE International Electron Devices Meeting (IEDM 2013)
We report the first mechanically flexible amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) vertical thin-film transistors (VTFTs) with 500 nm channel length, fabricated on a freestanding plastic foil, using a low temperature process <;150°C. The VTFTs exhibit a well-shaped transfer characteristic, with an on/off current ratio >10 7 and a threshold voltage of 2.2 V. We demonstrate full device functionality down to 5 mm bending radius, even after 1000 bending cycles. These results proof that VTFTs are feasible for realizing compact and bendable electronic systems.
Focused ion beam milling for the fabrication of 160 nm channel length IGZO TFTs on flexible polymer substrates
Münzenrieder, Niko Stephan; Shorubalko, Ivan; Petti, Luisa; et al. (2020)
Flexible and Printed Electronics
The quest for short channel length transistors is an important challenge in the semiconductor industry. A similar trend is observed in the field of flexible electronics where sensor conditioning circuits and transceivers have to be realized on plastic foils. Here the use of a focused Ga+ ion beam (FIB) to structure the channel of a flexible InGaZnO-based thin-film transistor (TFT) is presented. The resulting flexible TFT exhibits a channel length of 160nm and an effective field effect mobility of 4 cm(2) V-1 s(-1). Furthermore, the optimized Ga+ beam milling does not damage the Al2O3 gate insulator underneath, leading to a gate leakage current of <200 pA. The extreme channel length demonstrates that focused ion beams can complement conventional fabrication approaches, overcoming current limitations imposed by flexible substrates. While the dimensions result in short channel effects and a drain conductance of 25 mu S limiting the DC applicability of the FIB TFT, the device also exhibits a high internal gain of 3.4dB. Consequently, a transit frequency of 6 MHz 19 MHz <= 0.5V. This shows that highly scaled flexible TFTs for analog circuits can be fabricated by ion beam milling.
Flexible InGaZnO TFTs with fmax above 300 MHz
Münzenrieder, Niko Stephan; Ishida, Koichi; Meister, Tilo; et al. (2018)
IEEE Electron Device Letters
Long-Term Aging of Al2O3 Passivated and Unpassivated Flexible a-IGZO TFTs
Costa, Julio César; Kermani, Arash Pour Yazdan Panah; Cantarella, Giuseppe; et al. (2020)
IEEE Transactions on Electron Devices
Amongst the new materials studied for the fabrication of high-performance flexible thin-film transistors (TFTs), amorphous indium-gallium-zinc-oxide (a-IGZO) exhibits a combination of advantages that enables its application in commercial electronics. Hence, it is crucial to understand the electrical stability of a-IGZO TFTs over long periods of time. In this work, we present the effects of long-term aging on Al 2 O 3 passivated and unpassivated flexible a-IGZO TFTs over a period of 80 months ( ≈6.5 years). It is found that although remaining functional, these devices are influenced by different instability effects. More specifically, positive gate bias stress experiments indicate that the Al2O3 passivation layer contributes to the degradation of the devices’ performance. These results show that the Al2O3 passivation, although beneficial to the initial device stability, does not prevent the degradation of the passivated devices in comparison with their unpassivated counterparts after long periods of storage. © 2020 IEEE.
3.5mW 1MHz AM detector and digitally-controlled tuner in a-IGZO TFT for wireless communications in a fully integrated flexible system for audio bag
Meister, Tilo; Ishida, Koich; Carta, Corrado; et al. (2016)
2016 IEEE Symposium on VLSI Circuits (VLSI-Circuits)
We developed a fully flexible AM (amplitude modulation) radio receiver suitable for integration in an “audio bag”, by exploiting the heterogeneous integration of several fully flexible technologies. In this paper, we present a 2.9 mW 2-bit digitally-controlled tuner with a 576 kHz tuning range, a 3.5 mW 1 MHz AM detector and their integration in such a fully-flexible system. Their optimized power consumptions are essential because thin flexible batteries and organic solar cells serve as power supply. The circuits are fabricated in a low-temperature amorphous indium gallium zinc oxide (a-IGZO) technology. For the system integration textile techniques as well as flexible inkjet-printed packages and printed circuit boards (IPCBs) were used.
Influence of Mechanical Bending on Flexible InGaZnO-Based Ferroelectric Memory TFTs
Petti, Luisa; Münzenrieder, Niko Stephan; Salvatore, Giovanni A.; et al. (2014)
IEEE Transactions on Electron Devices
Future flexible electronic systems require memory devices combining low-power operation and mechanical bendability. Here, we present mechanically flexible amorphous InGaZnO (a-IGZO) memory thin-film transistors (TFTs) with a ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] gate insulator. Memory operation is demonstrated with a memory window of 3.2 V and a memory ON/OFF ratio of 1.5×10 6 (gate-source voltage sweep of ±6 V). The measured mobility of 8 cm 2 V -1 s -1 and the ON/OFF current ratio of 10 7 are comparable with the values for reference TFTs fabricated on the same substrate. To use memory TFTs in flexible applications, it is crucial to understand their behavior under mechanical strain. Flexible memory and reference TFTs are characterized under bending radii down to 5.5 mm, corresponding to tensile and compressive strain of ≈ ±0.6%. For both memory and reference TFTs, tensile strain causes negative threshold voltage shifts and increased drain currents, whereas compressive strain results in the opposite effects. However, memory TFTs, compared with reference TFTs, exhibit up to 8× larger threshold voltage shifts and 17× larger drain current variations. It is shown that the strain-dependent properties of a-IGZO can only explain the shifts observed in reference TFTs, whereas the variations in memory TFTs are mainly caused by the piezoelectric properties of P(VDF-TrFE).
Improvement of contact resistance in flexible a-IGZO thin-film transistors by CF4/O2 plasma treatment
Knobelspies, Stefan; Takabayashi, Alain; Daus, Alwin; et al. (2018)
Solid-State Electronics
Soft magnetic microrobots with remote sensing and communication capabilities
Gao, Quan; Kim, Min-Soo; von Arx, Denis; et al. (2025)
Nature Communications
Remote communication in small-scale robotics offers a powerful way to enhance their capabilities, introducing options for state monitoring, multi-agent collaboration, and autonomous operation. Integrating common remote communication tools, such as antennas, into microrobots is challenging with conventional design and manufacturing techniques. We propose a concept that integrates shape-reconfigurable soft microrobots with flexible electronics, leveraging their elastic mechanical properties to enable remote communication. This approach, based on photolithography processes, is scalable and adaptable to various sensing applications. As a proof of concept, we present a microrobot, which integrates a thermoresponsive magnetic hydrogel, an anisotropic support structure, and a flexible dipole antenna into a cohesive three-layered design. The microrobot can morph from a helical shape at low-temperatures to a planar shape at high-temperatures. This shape transformation can be remotely detected by external radio communication receivers, enabling shape-state recognition and environmental temperature sensing. Furthermore, we show that the collective behavior of multiple microrobots enhances the recognition performance by amplifying the signal. The concept represents a significant advancement in co-engineering smart materials and flexible electronics, illustrating an approach of microrobotic embodied intelligence by integrating environmental monitoring, magnetic navigation, and remote signaling.

Publications1 - 10 of 13

Niko Stephan Münzenrieder

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