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Improved capping layer for spin valve sensors

IP.com Disclosure Number: IPCOM000015368D
Original Publication Date: 2002-Jan-28
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 62K

Publishing Venue

IBM

Abstract

Disclosed is a bottom spin valve structure of the type Seed/PtMn/CoFe/Ru/CoFe/Cu/FL/NiFeCr/Ta, that has a thin high, resistivity, non-magnetic NiFeCr layer inserted between the free layer (FL) and Ta cap. Introduction of NiFeCr interlayer reduces current shunting and improves giant magnetoresistance (GMR) coefficient DR/R, by reducing magnetically inactive or “dead” layer at the FL/Cap interface for a given physical thickness of the free layer and improves read sensor amplitude and magnetic stability. NiFeCr acts as a diffusion barrier that forms a better structural quality and more thermally robust interface with the free layer than Ta, which is important since after sensor deposition the spin valve stack is subjected to a variety of thermal steps during the subsequent head fabrication process. As is shown in the figure, about 7A of NiFeCr interlayer inserted between free layer and Ta cap recovers 7A* of magnetic thickness of the free layer in the o spin valve stack Seed/PtMn/CoFe/Ru/CoFe/Cu/CoFe/NiFe/NiFeCr/Ta annealed at 245C for 5 hours. Corresponding coupon data shown in the table indicates, that a spin valve with NiFeCr/Ta cap has both higher DR/R and sheet resistance, Rs, and the same soft magnetic properties, compared to a spin valve stack with a conventional Ta cap, for a given magnetic thickness of the free layer. On the device level, finished heads with NiFeCr/Ta-capped sensor showed about 5% higher amplitude and better magnetic stability than these with Ta-capped sensor.

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Improved capping layer for spin valve sensors

   Disclosed is a bottom spin valve structure of the type Seed/PtMn/CoFe/Ru/CoFe/Cu/FL/NiFeCr/Ta, that has a thin high, resistivity, non-magnetic NiFeCr layer inserted between the free layer (FL) and Ta cap. Introduction of NiFeCr interlayer reduces current shunting and improves giant magnetoresistance (GMR) coefficient DR/R, by reducing magnetically inactive or "dead" layer at the FL/Cap interface for a given physical thickness of the free layer and improves read sensor amplitude and magnetic stability. NiFeCr acts as a diffusion barrier that forms a better structural quality and more thermally robust interface with the free layer than Ta, which is important since after sensor deposition the spin valve stack is subjected to a variety of thermal steps during the subsequent head fabrication process. As is shown in the figure, about 7A of NiFeCr interlayer inserted between free layer and Ta cap recovers 7A* of magnetic thickness of the free layer in the ospin valve stack Seed/PtMn/CoFe/Ru/CoFe/Cu/CoFe/NiFe/NiFeCr/Ta annealed at 245C for 5 hours. Corresponding coupon data shown in the table indicates, that a spin valve with NiFeCr/Ta cap has both higher DR/R and sheet resistance, Rs, and the same soft magnetic properties, compared to a spin valve stack with a conventional Ta cap, for a given magnetic thickness of the free layer. On the device level, finished heads with NiFeCr/Ta-capped sensor showed about 5% higher amplitud...