Technologies for Spintronics
Fraunhofer ENAS has been active in the field of Spintronics since 2010, with focus on magnetic field sensors based on the GMR (giant magnetoresistance) or TMR (tunneling magnetoresistance) effects, with particular emphasis on the development of sensors with multidimensional sensitivity. The realization of specific applications (e.g. for the determination of electrical current intensity, a work piece position, distances or rotations, in the automotive or industrial sector) often relies on further research and development on system and sensor level. Whereas system level mostly means multiphysical simulations for a particular sensor design (sensor plus permanent or electromagnet embedded in the application area), sensor level development includes e.g. compatibility studies, analysis of contaminations due to process variations, as well as considerations in terms of required thermal and magnetic properties to meet a specific application.
The standard layer stacks, composed of several different materials with thicknesses partly even down to the sub-nm range, are typically prepared by means of magnetron sputtering and are subsequently micro- or nanofabricated through different patterning technologies (bottom-up, top-down). The overall process from first wafer treatments until the final sensor packaging can be done at Fraunhofer ENAS for processing substrates up to 200 mm wafer diameter. The sensor preparation is complemented by a broad range of methods available for in situ process monitoring, and the sensor characterization with focus on magnetic and electrical properties.
Equipment and technologies for spintronic applications
- Deposition of complex layer stacks on wafer level
- Lithography (UV-stepper, e-beam), including mask design
- Micro- and nanopatterning (ion-milling, reactive ion and ion beam etching, lift-off, etc.)
- Low-temperature CVD (e.g. Si-O, Si-N)
- Chemical mechanical planarization and polishing (CMP)
- Monolithically integrated 2D magnetic field sensors based on GMR spin valves
Publications and patents
O. Ueberschär, R. Ecke, S. Schulz, P. Matthes, and M. Albrecht, 3D Magnetfeldsensor und Verfahren zu dessen Herstellung, patent application at Deutsches Patent und Markenamt, appl. no. 102014202770.5, filed February 14, 2014, published 20.08.2015 (WO2015121447 A1).
M. Almeida, A. Sharma, P. Matthes, N. Köhler, S. Busse, M. Müller, O. Hellwig, A. Horn, D. R. T. Zahn, G. Salvan, and S. E. Schulz, Laser induced crystallization of Co–Fe–B films, Sci. Rep. 11, 14104 (2021).
L. Ramasubramanian, A. Kákay, C. Fowley, O. Yildirim, P. Matthes, S. Sorokin, A. Titova, D. Hilliard, R. Boettger, R. Hübner, S. Gemming, S. E. Schulz, F. Kronast, D. Makarov, J. Faßbender, and A. Deac, Tunable magnetic vortex dynamics in ion-implanted permalloy disks, ACS Appl. Mater. Interfaces 12, 27812 (2020). https://doi.org/10.1021/acsami.0c08024
A. Sharma, M. Almeida-Hoffmann, P. Matthes, O. Hellwig, C. Kowol, S. E. Schulz, D. R. T. Zahn, and G. Salvan, Crystallization of optically thick films of CoxFe80−xB20: Evolution of optical, magneto-optical, and structural properties, Phys. Rev. B 101, 054438 (2020). https://doi.org/10.1103/PhysRevB.101.054438
Timur Slapke, interviewee P. Matthes et al, special item „Zukunftsfeld Spintronik, Elektronik mit dem richtigen Dreh“, VAA Magazin, February 2020