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Novel Process to Improve Soft Bias Film Properties in the Magneto-resistive Sensor

IP.com Disclosure Number: IPCOM000107493D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 1 page(s) / 40K

Publishing Venue

IBM

Related People

Howard, JK: AUTHOR [+2]

Abstract

In the magneto-resistive (MR) sensor, a soft magnetic layer, which provides adequate transverse bias, is often incorporated to optimize the sensor performance. Many materials have been considered for this application. This includes ternary NiFe alloys with addition of Ta, Ti, Mo, Cr, Rh, etc., and Co-based amorphous alloys. Desirable properties for this application include: 1. High electrical resistivity to reduce currentshunting effect. 2. High permeability to provide reliable bias scheme. 3. Zero magnetoresistance ratio to minimize sidereadings.

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Novel Process to Improve Soft Bias Film Properties in the Magneto-resistive Sensor

      In the magneto-resistive (MR) sensor, a soft magnetic layer,
which provides adequate transverse bias, is often incorporated to
optimize the sensor performance.  Many materials have been considered
for this application.  This includes ternary NiFe alloys with
addition of Ta, Ti, Mo, Cr, Rh, etc., and Co-based amorphous alloys.
Desirable properties for this application include: 1. High electrical
resistivity to reduce currentshunting effect. 2. High permeability to
provide reliable bias scheme.  3. Zero magnetoresistance ratio to
minimize sidereadings.

      It is found that by adding a small amount of nitrogen (N2) in
the argon (Ar) sputtering gas during deposition of these films can
drastically improve the properties required for soft-bias film
application.  That is, the film will have higher resistivity, much
reduced magnetoresistance ratio and lower coercivity (Hc) and
anisotropy (Hk).  The latter implies high permeability.

      We have found that these improved properties could result from
reduction of grain size of these films.  It is therefore believed
that other gases, such as CO, NH3, CH4, NO2, N20, etc., known to
reduce the grain size of the growing films would yield the similar
results.

      Disclosed anonymously.