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 angles 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