Published Scientific Papers
Slanted gratings with varying slant angle by localized reactive ion beam processing
David Stark, Carsten Schulze, Marcel Demmler, Matthias Nestler, Michael Zeuner – scia Systems GmbH
Augmented and mixed reality applications have recently gained large interest. In order to fabricate lightweight near eye displays surface relief gratings are used for coupling the light from the source into the light guide and out of the light guide towards the eye. To suppress higher diffraction orders and thus maximize the light yield those gratings are slanted. In order to achieve high field of view variation of the slant angle is desirable yet rather difficult to achieve. Ion beam trimming (IBT) is a method well established in MEMS and sensor manufacturing to locally modify the thickness of a layer or substrate in order to achieve a desired target topography. This method has been adapted towards fabrication of surface relief gratings with both varying slant angle and varying trench depth.
To download the paper, follow the link: https://www.spiedigitallibrary.org
Sputter deposition of undoped and doped SiO2 films for temperature compensated SAW components
H. Bartzsch; J. Hildisch ; K. Täschner ; S. Barth – Fraunhofer FEP; R. Rückriem ; M. Nestler – scia Systems GmbH
Reactive magnetron sputter deposition is shown to be a suitable method for depositing Fluorine doped silica films for temperature compensated SAW devices.
To download the paper, follow the link: https://ieeexplore.ieee.org/document/8925909
Ion Beam Figuring of X-Ray Mirrors
C.Schulze, M. Nestler, M.Zeuner - scia Systems GmbH
A significant portion toward understanding evolution of the universe comes from X-ray astronomy since many astronomical objects of interest, such as black holes, supernovae, and distant galaxies, emit radiation in the X-ray band. As basically all materials have almost unity refractive index for X-rays focusing X-ray beams is only possible by reflection at grazing incidence. Due to the low photon flux of the objects under study (few photons per hour) each individual photon is of particular interest. Thus, the collective area of X-ray telescopes needs to be as large as possible which is achieved by a large amount of concentrically nested X-ray mirrors whose shape needs to be ideal fitting to the designed geometry for high image quality. Due to the mirrors' curvature even state of the art mechanical machining and chemical mechanical polishing processes leave a residual surface error of several hundred nanometers. Those residual errors can be significantly reduced by ion beam figuring.
To download the paper, follow the link: https://www.spiedigitallibrary.org
Structuring of Spintronic Sensors by Ion Beam Milling with in-situ Insulator Deposition
M. Nestler, S. Rumbke, E. Loos - scia Systems GmbH, A. Böhnke, N. Dohmeier - Bielefeld University
We demonstrate that high-quality CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) can be produced by combining magnetron sputtering, UV lithography, and ion beam milling (IBM). Particularly, we study the effect of different milling angles on the tunneling magnetoresistance (TMR). Furthermore, we investigate the quality of devices manufactured by depositing the insulator in-situ subsequent to milling. Using a secondary ion mass spectrometer (SIMS), all layers can be detected while milling, enabling us to precisely define the mill stops. We found TMR values of up to 140 % for a milling angle of 30° and 90 % for a two angle milling process at 20° and 65°, proving that no critical sidewall redeposition of conductive material takes place.
To download the paper, follow the link: http://www.ama-science.org/proceedings/details/2653
Fabrication of high-sensitivity pyroelectric sensors by ion beam etching
R. Rückriem, M. Zeuner - scia Systems GmbH, R. Köhler - DIAS INFRARED GMBH
Ion beam etching of pyroelectric sensors made of lithium tantalate (LT) is presented in order to get a higher specific detectivity D* compared to standard sensors. We present the etching tool which applies argon ion beam etching in production environment. The etching homogeneity was investigated by a standard silicon oxide etch and a twelve hour silicon etch with photoresist mask. Both show a homogeneity of +/- 0.7 % and a good compliance. Further investigations were done in a twelve hour process regarding the stability of the ion current regulation and ion current density. In the first two hours after process start the main variation of power and ion current density takes place. Afterwards, the system reached a steady-state. After etching of the LT samples, an analysis of the removed material and emerged etching walls was done. Finally, the important D* was compared between an ion-etched and a non-ion etched pyroelectric sensor.
To download the paper, follow the link: http://www.ama-science.org/proceedings/details/2406
Multilayer coating of optical substrates by ion beam sputtering
M. V. Daniel, M. Demmler – scia Systems GmbH
Ion beam sputtering is well established in research and industry, despite its relatively low deposition rates compared to electron beam evaporation. Typical applications are coatings of precision optics, like filters, mirrors, and beam splitter. Anti-reflective or high-reflective multilayer stacks benefit from the high mobility of the sputtered particles on the substrate surface and the good mechanical characteristics of the layers. This work gives the basic route from single layer optimization of reactive ion beam sputtered Ta2O5 and SiO2 thin films towards complex multilayer stacks for high-reflective mirrors and anti-reflective coatings. Therefore, films were deposited using different oxygen flow into the deposition chamber. Afterwards, mechanical properties (density, stress, surface morphology, crystalline phases) and optical properties (reflectivity, absorption and refractive index) were characterized. This knowledge was used to deposit a multilayer coating for a high-reflective mirror.
To download the paper, follow the link: https://doi.org/10.1117/12.2279788
New coating system for direct-deposition of sensors on components of arbitrary size: A novel approach allowing for thinner sensors with higher measuring accuracy
D. Klaas, J. Becker, M. C. Wurz - Institute of Micro Production Technology, Leibniz Universität Hannover,
J. Schlosser, M. Kunze – scia Systems GmbH
A new coating system for the deposition of sensors and thin layers directly onto components of arbitrary size has been invented at the Institute of Micro Production Technology. This system allows for thinner sensors without any carrier substrate and with a higher measuring accuracy. Within this paper, the basic setup and the functional principle of the new coating system is presented. The deposition process sequence is described and the system is characterized concerning layer homogeneity and evacuation time.
To download the paper, follow the link: https://ieeexplore.ieee.org/abstract/document/7808440/
Ion beam trimming in manufacturing of acoustic wave devices
M.Zeuner, K.Gündel, T.Dunger, M.Demmler, M.Nestler – scia Systems GmbH
The manufacturing of devices for mobile communication technology demands an extremely high precision regarding geometrical dimensions. In case of acoustic wave ﬁlters, surface acoustic wave (SAW) and bulk acoustic wave (BAW) resonators, the quality depends a lot on the dimensions of several layers consisting of different material, hence an adjustment regarding homogeneity in sub-nm range has to be guaranteed. Thin ﬁlm deposition processes, used commonly in the industrial mass production in semiconductor industry, are not able to reach these demanding requirements in order to achieve the necessary device quality. On account of this a space-resolved correction of layer dimensions as a subsequent manufacturing step is mandatory [1, 2]. Within the article a technology of space-resolved correction of device wafer is described. The correction takes place due to a focused broad ion beam and a movement of wafer in front of it. Hence the ion beam etches the surface of the wafer and the modulated dwell time of the beam on a certain position of the wafer deﬁnes the amount of ablated material in order to achieve the target geometry or thickness all over the wafer.
To download the paper, follow the link: http://www.nanoindustry.su/files/article_pdf/4/article_4630_330.pdf