A Study of Microstructure and Magnetic Properties of Spin Valves Fabricated under the Extremely Clean Sputtering Process.

Accession number;99A0938084
Title;A Study of Microstructure and Magnetic Properties of Spin Valves Fabricated under the Extremely Clean Sputtering Process.
Author; UNEYAMA KAZUHIRO (Tohoku Univ.)
Journal Title;Record of Electrical and Communication Engineering Conversazione, Tohoku University
Journal Code:F0511A
ISSN:0385-7719
VOL.68;NO.1;PAGE.73-76(1999)
Figure&Table&Reference;FIG.5, REF.4
Pub. Country;Japan
Language;Japanese
Abstract;Areal density of hard disks has grown rapidly by 60% per year. In order to induce adequate magnetic properties of the metallic thin-film devices such as recording media and heads, it becomes more and more important to control the microstructure of them. Since the impurities in the sputtering atmosphere affect strongly on the initial film growth, the highly purified atmosphere will be required for the thin-film device fabrication, in order to improve the microstructural controllability of sputter-deposition process. In the present study, we developed a specialized multi-sputtering system and fabricated ultra-thin spin valve GMR films by using this system. The newly developed sputtering system enables to realize 10-12Torr vacuum condition and to supply ultra clean processing gases; the impurity level in the sputtering atmosphere was less than 10-4 times, comparing with that of the sputtering systems normally used. The MR ratio of an optimized spin valve, sub./Ta/Ni-Fe/Co/Cu/Co/Mn-Ir/Ta, achieved to 9.7%, even in the total thickness of 148.ANGS. except for the capping Ta layer. When the same structure was fabricated by degrading the base pressure of chamber to 10-7Torr, the exchange biasing effect was no longer observed and the MR ratio suddenly dropped to 0.9%. The extremely clean sputtering process is concluded to be greatly effective to realize ultra-thin-film devices with excellent magnetic properties. (author abst.)
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