Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2001-08-02
2004-06-22
Heinz, A. J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S327300
Reexamination Certificate
active
06754048
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to methods for fabricating magnetic sensor elements. More particularly, the present invention relates to methods for fabricating non-parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements.
2. Description of the Related Art
The recent and continuing advances in computer and information technology have been made possible not only by the correlating advances in the functionality, reliability and speed of semiconductor integrated circuits, but also by the correlating advances in the storage density and reliability of direct access storage devices (DASDs) employed in digitally encoded magnetic data storage and retrieval.
Storage density of direct access storage devices (DASDs) is typically determined as areal storage density of a magnetic data storage medium formed upon a rotating magnetic data storage disk within a direct access storage device (DASD) magnetic data storage enclosure. The areal storage density of the magnetic data storage medium is defined largely by the track width, the track spacing and the linear magnetic domain density within the magnetic data storage medium. The track width, the track spacing and the linear magnetic domain density within the magnetic data storage medium are in turn determined by several principal factors, including but not limited to: (1) the magnetic read-write characteristics of a magnetic read-write head employed in reading and writing digitally encoded magnetic data from and into the magnetic data storage medium; (2) the magnetic domain characteristics of the magnetic data storage medium; and (3) the separation distance of the magnetic read-write head from the magnetic data storage medium.
With regard to the magnetic read-write characteristics of magnetic read-write heads employed in reading and writing digitally encoded magnetic data from and into a magnetic data storage medium, it is known in the art of magnetic read-write head fabrication that magnetoresistive (MR) sensor elements employed within magnetoresistive (MR) read-write heads are generally superior to other types of magnetic sensor elements when employed in retrieving digitally encoded magnetic data from a magnetic data storage medium. In that regard, magnetoresistive (MR) sensor elements are generally regarded as superior since magnetoresistive (MR) sensor elements are known in the art to provide high output digital read signal amplitudes, with good linear resolution, independent of the relative velocity of a magnetic data storage medium with respect to a magnetoresistive (MR) read-write head having the magnetoresistive (MR) sensor element incorporated therein.
Within the general category of magnetoresistive (MR) sensor elements, magnetoresistive (MR) sensor elements which employ multiple magnetoresistive (MR) layers (typically including a pair of magnetoresistive (MR) layers), such as but not limited to dual stripe magnetoresistive (DSMR) sensor elements and spin valve magnetoresistive (DSVMR) sensor elements, and in particular magnetoresistive (MR) sensor elements which employ multiple magnetoresistive (MR) layers at least one of which is magnetically biased to provide non-parallel magnetic bias directions of the multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements, such as nominally anti-parallel longitudinally magnetically biased dual stripe magnetoresistive (DSMR) sensor elements and nominally perpendicularly magnetically biased spin valve magnetoresistive (DSVMR) sensor elements, are presently of considerable interest insofar as the magnetically biased magnetoresistive (MR) layers employed within such magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements typically provide enhanced magnetic read signal amplitude and fidelity in comparison with single stripe magnetoresistive (MR) sensor elements, non-magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements and parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements.
While non-parallel magnetically biased multiple magnetoresistive (R) layer magnetoresistive (MR) sensor elements such as but not limited to non-parallel longitudinally magnetically biased dual stripe magnetoresistive (DSMR) sensor elements and non-parallel perpendicularly magnetically biased dual spin valve magnetoresistive (DSVMR) sensor elements are thus desirable within the art of digitally encoded magnetic data storage and retrieval, non-parallel multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements are nonetheless not fabricated entirely without problems in the art of magnetoresistive (MR) sensor element fabrication. In particular, as a data track width within a magnetic medium employed within digitally encoded magnetic data storage and retrieval decreases, it becomes increasingly important that a read track width within a non-parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor element employed in reading the data within the data track be uniformly magnetically biased (i.e. have a uniform cross-track magnetic bias profile). Uniform cross-track magnetic bias profiles are desirable within read track widths of non-parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements since such uniform cross-track magnetic bias profiles provide for optimal magnetic read signal amplitudes within such non-parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor elements.
It is thus towards the goal of providing, for use within magnetic data storage and retrieval, a method for forming a non-parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor element with a uniform cross-track magnetic bias profile across a read track width of the non-parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor element, as well as a non-parallel magnetically biased multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor element formed in accord with the method, that the present invention is most generally directed.
Various methods and resultant magnetoresistive (MR) sensor element structures have been disclosed in the art of magnetoresistive (MR) sensor element fabrication for forming magnetically biased magnetoresistive (MR) sensor elements with enhanced functionality, enhanced reliability or other desirable properties.
For example, Voegeli et al., in U.S. Pat. No. 5,561,896, discloses a method for fabricating, with enhanced longitudinal magnetic bias characteristics, enhanced fabrication simplicity and enhanced reliability, a longitudinally magnetically biased magnetoresistive (MR) sensor element for use within magnetic data storage and retrieval. The method employs an “H” shaped laminate formed of a soft magnetoresistive (MR) material layer laminated to an interdiffusion material layer, where upon thermally induced interdiffusion of the soft magnetoresistive (MR) material layer and the interdiffusion material layer there is formed a hard magnetic bias material layer therefrom, and where interdiffusion of the soft magnetoresistive (MR) material layer with the interdiffusion material layer is effected by an electrical pulsing through a pair of leg portions of the “H” but not a horizontal connector portion of the “H”, such that the pair of leg portions of the “H” is transformed into a pair of hard magnetic bias material layers while the horizontal connector portion of the “H” remains un-interdiffused as the soft magnetoresistive (MR) material layer which is longitudinally magnetically biased by the pair of hard bias magnetic bias material layers formed from the thermally interdiffused leg portions of the “H”.
In addition, Dovek et al., in U.S. Pat. No. 5,650,887, discloses a system for retrieving magnetic data from a magnetic data storage medium while employing a spin valve m
Li Min
Liao Simon H.
Ackerman Stephen B.
Headway Technologies Inc.
Heinz A. J.
Saile George O.
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