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Magnetoresistive Head with Integrated Varistor Employing Combined Varistor, Antiferromagnet Seed/Gap and Grounded First Shield

IP.com Disclosure Number: IPCOM000014427D
Original Publication Date: 2000-Apr-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 1 page(s) / 31K

Publishing Venue

IBM

Abstract

Described is a magnetic recording head having a magnetoresistive read sensor combined with an NiO seed/gap layer that is primarily used as an antiferromagnet (AFM) to provide exchange bias for the pinned layer of a spin valve (SV) sensor, but which also provides a varistor action in a structure that is essentially a

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  Magnetoresistive Head with Integrated Varistor Employing Combined Varistor, Antiferromagnet Seed/Gap and Grounded First Shield

   Described is a magnetic recording head having a magnetoresistive read sensor
combined with an NiO seed/gap layer that is primarily used as an antiferromagnet
(AFM) to provide exchange bias for the pinned layer of a spin valve (SV) sensor,
but which also provides a varistor action in a structure that is essentially a
metal oxide varistor (MOV) to protect the magnetoresistive read element from the
deleterious effects of electrostatic discharge (ESD) and electrical overstress
(EOS). The novel feature of the invention is the utilization of the NiO seed/gap
layer as an MOV/AFM combination in an integrated fashion within the head
structure by disposing it in direct contact with the sensor and lead proper.
Through the use of the existing lead or sensor metallurgy as one electrode in
contact with the NiO layer and the first shield as a grounded counter-electrode,
it is possible to shunt to ground electrical transients that would otherwise
damage a sensor which is becoming increasingly ESD/EOS sensitive due to the
device scaling that attends to the demands of ever increasing areal recording
densities.

   A preferred embodiment of the invention comprises an NiO layer, nominally 50nm
thick, disposed between the sensor and lead metallurgies of the head, and the
grounded first shield. This structure works in a passive, high-resistance mode
under normal operation of the head; but, when a voltage...