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Improved Spin Valves Structures with (Co-Fe)Ox Free layer

IP.com Disclosure Number: IPCOM000015125D
Original Publication Date: 2002-Jan-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Abstract

Disclosed is a spin valve stack structure with CoFe/CoFe-oxide free layer and CoFe oxidation process, which improves magnetic softness of the free layer and giant magnetoresistive (GMR) properties of the spin valve. Pure CoFe free layer has high coercivity, which reduces spin valve sensor sensitivity and gives rise to magnetic instability. In-situ, post deposition natural oxidation of CoFe free layer, prior to capping layer sputtering, reduces easy axis coercivity (Hce) of the free layer, while at the same time increases GMR coefficient (DR/R) and sheet resistance (Rs) of the spin valve, which should result in a higher amplitude and better magnetic stability of the spin valve sensor. To achieve good result, the oxygen exposure of CoFe free layer during in-situ, post deposition -3 natural oxidation should be in the range from 10 Torr-sec to 10-1Torr-sec. The DR/R, Rs, as well as easy and hard axis coercivities of the spin valve stacks (Seed/PtMn/CoFe/Ru/CoFe/Cu/Free Layer/Cap) with both CoFe/CoFe-oxide free layer -2 oxidized at 2x10 Torr-sec and conventional, non-oxidized CoFe free layer for comparison are shown in the Table. Free Layer Hce, Oe Hch, Oe

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Improved Spin Valves Structures with (Co-Fe)Ox Free layer

Disclosed is a spin valve stack structure with CoFe/CoFe-oxide free layer and CoFe oxidation process, which improves magnetic softness of the free layer and giant magnetoresistive (GMR) properties of the spin valve. Pure CoFe free layer has high coercivity, which reduces spin valve sensor sensitivity and gives rise to magnetic instability. In-situ, post deposition natural oxidation of CoFe free layer, prior to capping layer sputtering, reduces easy axis coercivity (Hce) of the free layer, while at the same time increases GMR coefficient (DR/R) and sheet resistance (Rs) of the spin valve, which should result in a higher amplitude and better magnetic stability of the spin valve sensor. To achieve good result, the oxygen exposure of CoFe free layer during in-situ, post deposition -3natural oxidation should be in the range from 10 Torr-sec to 10-1Torr-sec. The DR/R, Rs, as well as easy and hard axis coercivities of the spin valve stacks (Seed/PtMn/CoFe/Ru/CoFe/Cu/Free Layer/Cap) with both CoFe/CoFe-oxide free layer -2oxidized at 2x10 Torr-sec and conventional, non-oxidized CoFe free layer for comparison are shown in the Table.

Free Layer Hce,

Oe

Hch, Oe

DR/R, % Rs,

W/sq

CoFe 8.2 2.9 12.1 22.5

CoFe/CoFe-Oxide 4.3 2.9 12.7 23.7

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