Effects of pumping time on GMR and coercivity of RF-sputtered MRAM dual spin-valves

Author

Bae, Seongtae ; Matsushita, Nobuhiro ; Zurn, Shayne ; Sheppard, Larry ; Torok, E. James ; Judy, Jack H.

Author_Institution

Dept. of Electr. & Comput. Eng., Minnesota Univ., Minneapolis, MN, USA

Volume

36

Issue

5

fYear

2000

fDate

9/1/2000 12:00:00 AM

Firstpage

2853

Lastpage

2856

Abstract

The effects of residual oxygen in a deposition vacuum chamber on the GMR performance of RF-sputtered MRAM dual spin-valves have been studied by varying the pumping time while maintaining a constant base pressure of 5×10^-7 Torr. By increasing only the pumping time from 1.5 to 8 hours, the GMR ratio of Si/NiFe/Cu/Co/Cu/NiFe dual spin-valves increased from 1.2 to 2.9%, and coercivity of NiFe decreased from 11 to 5 Oe and coercivity of Co decreased from 80 to 15 Oe. According to depth profiles of the chemical composition using AES and XPS, the oxygen content decreased substantially with increasing pumping time. This result implies that the partial oxidation inside or at the interfaces of multilayers is a “GMR killer” which causes incomplete anti-parallel spin alignment of the dual spin valves

Keywords

Auger electron spectra; Permalloy; X-ray photoelectron spectra; cobalt; coercive force; copper; giant magnetoresistance; magnetic heads; magnetic multilayers; outgassing; oxidation; random-access storage; silicon; spin valves; sputter deposition; sputtered coatings; 1.5 to 8 hour; 5E-7 torr; Auger electron microscopy; GMR; RF-sputtered; Si-NiFe-Cu-Co-Cu-NiFe; X-ray photoelectron spectroscopy; antiparallel spin alignment; chemical composition depth profiles; coercivity; magnetic RAM dual spin-valves; multilayer interfaces; partial oxidation; pumping time effect; residual oxygen effects; vacuum chamber; Atomic force microscopy; Coercive force; Electron microscopy; Giant magnetoresistance; Impurities; Magnetic field measurement; Magnetic multilayers; Spectroscopy; Spin valves; Sputtering;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.908607

Filename

908607