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Fabian Kühnel, M.Sc.

Wissenschaftlicher Mitarbeiter


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Vortrag

  • Fabian Kühnel

Improving 3-Omega Method/Weiterentwicklung der 3-Omega Methode

In: Deggendorfer Wissenschaftliches Kolloquium

Technische Hochschule Deggendorf Technische Hochschule Deggendorf

  • 23.06.2022 (2022)
  • Elektrotechnik und Medientechnik
  • DIGITAL
Zeitschriftenartikel

  • Fabian Kühnel
  • Christoph Metzke
  • Jonas Weber
  • J. Schätz
  • G. Duesberg
  • Günther Benstetter

Investigation of Heater Structures for Thermal Conductivity Measurements of SiO2 and Al2O3 Thin Films Using the 3-Omega Method

In: Nanomaterials vol. 12

  • 04.06.2022 (2022)

DOI: 10.3390/nano12111928

A well-known method for measuring thermal conductivity is the 3-Omega (3ω) method. A prerequisite for it is the deposition of a metal heater on top of the sample surface. The known design rules for the heater geometry, however, are not yet sufficient. In this work, heaters with different lengths and widths within the known restrictions were investigated. The measurements were carried out on SiO2 thin films with different film thicknesses as a reference. There was a significant difference between theoretical deposited heater width and real heater width, which could lead to errors of up to 50% for the determined thermal conductivity. Heaters with lengths between 11 and 13 mm and widths of 6.5 µm or more proved to deliver the most trustworthy results. To verify the performance of these newfound heaters, additional investigations on Al2O3 thin films were carried out, proving our conclusions to be correct and delivering thermal conductivity values of 0.81 Wm-1 K-1 and 0.93 Wm-1 K-1 for unannealed and annealed samples, respectively. Furthermore, the effect of annealing on Al2O3 was studied, revealing a significant shrinking in film thickness of approximately 11% and an increase in thermal conductivity of 15%. The presented results on well-defined geometries will help to produce optimized heater structures for the 3ω method.
  • IQMA
  • NACHHALTIG
Zeitschriftenartikel

  • Fabian Kühnel
  • Jonas Weber
  • Christoph Metzke
  • Günther Benstetter

Thermo reflectance imaging re-imagined. A low-cost alternative for determining thermal conductivity

In: Wiley Analytical Science

  • (2021)

The thermal conductivity of thin films plays a central role in the development of new microelectronic components. If the heat generated in such components cannot be properly dissipated, hot spots form which can lead to component failure. However, determining thermal conductivities, especially in thin films, involves some effort and cost. In the field of processor and graphics card development, manufacturers are engaged in a fierce race to bring the most powerful product onto the market. This requires ever smaller transistors. In the meantime, the production process required for this has reached a size of 2 nm [1]. With increasing miniaturisation, the power density increases and thus also the generated heat. If this heat cannot dissipate effectively, the component fails. This is a decisive reason why the investigation of the thermal conductivity of thin films is becoming increasingly important. For the investigation of thermal conductivity there are a variety of measuring methods, such as the laser-flash method, the Micro-Raman method, the Scanning Thermal Microscopy, the 3-Omega method or the thermo-reflectance imaging method. As different as all these methods are, they have one thing in common: they are extremely complex and require very expensive equipment.
  • Elektrotechnik und Medientechnik
  • IQMA
  • NACHHALTIG
Zeitschriftenartikel

  • Fabian Kühnel
  • Jonas Weber
  • Christoph Metzke
  • Günther Benstetter

Thermoreflectance Imaging neu gedacht. Eine günstige Alternative zur Ermittlung der thermischen Leitfähigkeit

In: WILEY GIT Labor-Fachzeitschrift

  • (2021)

Die thermische Leitfähigkeit dünner Schichten spielt eine zentrale Rolle bei der Entwicklung neuer mikroelektronischer Bauteile. Kann die entstehende Wärme in solchen Bauteilen nicht richtig abgeführt werden, bilden sich Hotspots, welche zu Bauteilversagen führen können. Das Ermitteln der thermischen Leitfähigkeiten, insbesondere bei dünnen Schichten, ist allerdings mit einigem Aufwand und Kosten verbunden. Im Bereich der Prozessoren- und Grafikkartenentwicklung liefern sich die Hersteller ein erbittertes Rennen, um das leistungsstärkste Produkt auf den Markt zu bringen. Dazu werden immer kleinere Transistoren benötigt. Inzwischen ist der dafür benötigte Fertigungsprozess bei einer Größe von 2 nm [1] angelangt. Mit zunehmender Verkleinerung steigt die Leistungsdichte und somit auch die erzeugte Wärme. Kann diese nicht effektiv abfließen, versagt das Bauteil. Dies ist ein entscheidender Grund dafür, weshalb die Untersuchung der thermischen Leitfähigkeit von dünnen Schichten immer mehr an Bedeutung gewinnt. Zur Untersuchung der thermischen Leitfähigkeit gibt es eine Vielzahl an Messmethoden, wie zum Beispiel die Laser-Flash-Methode, die Micro-Raman Methode, die Scanning Thermal Microscopy, die 3-Omega Methode oder die Thermoreflectance Imaging Methode. So unterschiedlich alle diese Methoden auch sind, eines haben sie doch gemeinsam: Sie sind äußerst komplex und benötigen sehr teures Equipment.
  • Elektrotechnik und Medientechnik
  • IQMA
  • NACHHALTIG
Zeitschriftenartikel

  • Christoph Metzke
  • Fabian Kühnel
  • Jonas Weber
  • Günther Benstetter

Scanning Thermal Microscopy of Ultrathin Films: Numerical Studies Regarding Cantilever Displacement, Thermal Contact Areas, Heat Fluxes, and Heat Distribution

In: Nanomaterials vol. 11 pg. 491.

  • (2021)

DOI: 10.3390/nano11020491

New micro- and nanoscale devices require electrically isolating materials with specific thermal properties. One option to characterize these thermal properties is the atomic force microscopy (AFM)-based scanning thermal microscopy (SThM) technique. It enables qualitative mapping of local thermal conductivities of ultrathin films. To fully understand and correctly interpret the results of practical SThM measurements, it is essential to have detailed knowledge about the heat transfer process between the probe and the sample. However, little can be found in the literature so far. Therefore, this work focuses on theoretical SThM studies of ultrathin films with anisotropic thermal properties such as hexagonal boron nitride (h-BN) and compares the results with a bulk silicon (Si) sample. Energy fluxes from the probe to the sample between 0.6 µW and 126.8 µW are found for different cases with a tip radius of approximately 300 nm. A present thermal interface resistance (TIR) between bulk Si and ultrathin h-BN on top can fully suppress a further heat penetration. The time until heat propagation within the sample is stationary is found to be below 1 µs, which may justify higher tip velocities in practical SThM investigations of up to 20 µms−1. It is also demonstrated that there is almost no influence of convection and radiation, whereas a possible TIR between probe and sample must be considered.
  • Elektrotechnik und Medientechnik
  • NACHHALTIG
Vortrag

  • Fabian Kühnel
  • Christoph Metzke
  • Günther Benstetter

Thermal conductivity measurements of thin films using 3ω method

In: 7. Tag der Forschung

Deggendorf

  • 23.07.2020 (2020)
  • Elektrotechnik und Medientechnik
  • IQMA
  • NACHHALTIG
Zeitschriftenartikel

  • Christoph Metzke
  • Werner Frammelsberger
  • Jonas Weber
  • Fabian Kühnel
  • K. Zhu
  • M. Lanza
  • Günther Benstetter

On the Limits of Scanning Thermal Microscopy of Ultrathin Films

In: Materials vol. 13 pg. 518.

  • (2020)

DOI: 10.3390/ma13030518

Heat transfer processes in micro- and nanoscale devices have become more and more important during the last decades. Scanning thermal microscopy (SThM) is an atomic force microscopy (AFM) based method for analyzing local thermal conductivities of layers with thicknesses in the range of several nm to µm. In this work, we investigate ultrathin films of hexagonal boron nitride (h-BN), copper iodide in zincblende structure (γ-CuI) and some test sample structures fabricated of silicon (Si) and silicon dioxide (SiO2) using SThM. Specifically, we analyze and discuss the influence of the sample topography, the touching angle between probe tip and sample, and the probe tip temperature on the acquired results. In essence, our findings indicate that SThM measurements include artefacts that are not associated with the thermal properties of the film under investigation. We discuss possible ways of influence, as well as the magnitudes involved. Furthermore, we suggest necessary measuring conditions that make qualitative SThM measurements of ultrathin films of h-BN with thicknesses at or below 23 nm possible.
  • Elektrotechnik und Medientechnik
  • IQMA
  • NACHHALTIG
Vortrag

  • Christoph Metzke
  • Fabian Kühnel
  • Günther Benstetter

Thermal characterization of thin films using FEM simulations

In: 7. Tag der Forschung

Deggendorf

  • 23.07.2020 (2020)
  • Elektrotechnik und Medientechnik
  • IQMA
  • NACHHALTIG
Vortrag

  • Christoph Metzke
  • Günther Benstetter
  • Werner Frammelsberger
  • Jonas Weber
  • Fabian Kühnel

Temperature dependent investigation of hexagonal boron nitride films using scanning thermal microscopy . Poster presentation

In: 6th Nano Today Conference 2019

NanoBio Lab Lisbon, Portugal

  • 16.-20.06.2019 (2019)
  • IQMA
  • Elektrotechnik und Medientechnik
  • NACHHALTIG