Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1998-03-20
2002-12-17
Renner, Craig A. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06496333
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to dual stripe magnetoresistive (DSMR) sensor elements employed in dual stripe magnetoresistive (DSMR) read-write heads for magnetic data storage and retrieval. More particularly, the present invention relates to a method for forming a self-aligned dual stripe magnetoresistive (DSMR) sensor element employed within a dual stripe magnetoresistive (DSMR) read-write head for magnetic data storage and retrieval.
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 storage density 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 measured 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) enclosure. The areal storage density 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 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 into and from the magnetic data storage medium; (2) the magnetic domain characteristics of the magnetic data storage medium which is formed upon the rotating magnetic data storage disk; and (3) the separation distance of the magnetic read-write head from the rotating magnetic data storage disk.
With regard to magnetic read-write heads employed in reading and writing digitally encoded magnetic data into and from a magnetic data storage disk, it has become common in the art to employ magnetoresistive (MR) sensor elements, and in particular dual stripe magnetoresistive (DSMR) sensor elements, as read elements within those magnetic read-write heads since magnetoresistive (MR) sensor elements, and in particular dual stripe magnetoresistive (DSMR) sensor elements, provide high output digital signals, with good linear resolution, independent of the relative velocity of a magnetic data storage medium with respect to the magnetoresistive (MR) sensor element or the dual stripe magnetoresistive (DSMR) sensor element.
Although dual stripe magnetoresistive (DSMR) read-write heads employing dual stripe magnetoresistive (DSMR) sensor elements have thus become quite common in reading and writing digitally encoded magnetic data into and from magnetic data storage media, dual stripe magnetoresistive (DSMR) read-write heads are not entirely without problems. In particular, it is known in the art that dual stripe magnetoresistive (DSMR) read-write heads of optimal read performance are typically only obtained when there is a matching of electrical and magnetic properties between the two magnetoresistive (MR) layers within the dual-stripe magnetoresistive (DSMR) sensor element from which is formed the dual stripe magnetoresistive (DSMR) read-write head. In general, the factors which affect the matching of the two magnetoresistive (MR) layers within a dual stripe magnetoresistive (DSMR) sensor element include but are not limited to: (1) the physical widths of the two magnetoresistive (MR) layers; (2) the alignment of the two magnetoresistive (MR) layers; (3) the read widths of the two magnetoresistive (MR) layers; (4) the sheet resistances of the two magnetoresistive (MR) layers; and (5) the magnetic properties of the two magnetoresistive (MR) layers. As areal density of digitally encoded magnetic data increases, tolerances within the foregoing factors typically need to be minimized to assure optimal read characteristics of digitally encoded magnetic data read with dual stripe magnetoresistive (DSMR) read-write heads. In particular, it is desired in order to assure optimal read properties of a dual stripe magnetoresistive (DSMR) sensor element to eliminate or minimize the tolerance variations with respect to width and/or alignment between the two magnetoresistive (MR) layers within the dual stripe magnetoresistive (DSMR) sensor element. It is towards that goal that the present invention is directed.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method for minimizing tolerance variations with respect to the width and/or alignment between the two magnetoresistive (MR) layers within a dual stripe magnetoresistive (DSMR) sensor element.
A second object of the present invention is to provide a method in accord with the first object of the present invention, which method is readily manufacturable.
In accord with the objects of the present invention, there is provided by the present invention a method for minimizing tolerance variations with respect to width and/or alignment between the two magnetoresistive (MR) layers within a dual stripe magnetoresistive (DSMR) sensor element, as well as the dual stripe magnetoresistive (DSMR) sensor element formed through the method. To practice the method of the present invention, there is first provided a substrate having formed thereupon a pair of patterned first conductor lead layers which in turn has formed and aligned thereupon a pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers, where the horizontal separation of the pair of patterned first conductor lead layers and the pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers defines a track width of the substrate. There is then formed upon the substrate layer a blanket first magnetoresistive (MR) layer, where the blanket first magnetoresistive (MR) layer contacts and completely covers the track width of the substrate and contacts and at least partially covers the pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers. There is then formed upon the blanket first magnetoresistive (MR) layer a blanket inter-stripe dielectric layer. There is then formed upon the blanket inter-stripe dielectric layer a blanket second magnetoresistive (MR) layer. There is then formed upon the blanket second magnetoresistive (MR) layer a first lift off stencil. The first lift off stencil comprises: (1) a first etched patterned soluble underlayer; and (2) a first patterned masking layer formed upon and overhanging the first etched patterned soluble underlayer, where the first lift off stencil completely overlaps the track width of the substrate and at least partially overlaps the pair of patterned first anti-ferromagnetic longitudinal magnetic biasing layers. There is then employed the first lift off stencil as a first etch mask in forming from the blanket second magnetoresistive (MR) layer, the blanket inter stripe dielectric layer and the blanket first magnetoresistive (MR) layer a patterned second magnetoresistive (MR) layer, a patterned inter stripe dielectric layer and a patterned first magnetoresistive (MR) layer with fully aligned edges. There is then employed the first lift off stencil as a first lift off mask to form a patterned dielectric layer over the substrate, where the patterned dielectric layer covers the fully aligned edges of the patterned second magnetoresistive (MR) layer, the patterned inter stripe dielectric layer and the patterned first magnetoresistive (MR) layer. There is then removed the first lift off stencil from the patterned second magnetoresistive (MR) layer. There is then formed a second lift off stencil upon the patterned second magnetoresistive (MR) layer. The second lift off stencil comprises: (1) a second etched patterned soluble underlayer; and (2) a second patterned mask layer formed upon and overhanging the second etched patterned soluble underlayer, where the width of the second lift off stencil
Chen Mao-Min
Han Cherng-Chyi
Ackerman Stephen B.
Headway Technologies Inc.
Renner Craig A.
Saile George O.
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