Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1998-09-04
2001-10-23
Letscher, George J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06307721
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 magnetoresistive (MR) sensor elements with attenuated electrical leakage.
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) read-write heads are generally superior to other types of magnetic readwrite heads when employed in retrieving digitally encoded magnetic data from a magnetic data storage medium. In that regard, magnetoresistive (MR) read-write heads are generally regarded as superior since magnetoresistive (MR) read-write heads 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.
While magnetoresistive (MR) read-write heads are thus desirable within the art of digitally encoded magnetic data storage and retrieval, magnetoresistive (MR) read-write heads are nonetheless not entirely without problems within the art of digitally encoded magnetic data storage and retrieval. In that regard, it has become increasingly more difficult to form magnetoresistive (MR) read-write heads with increasingly thinner read gap thicknesses (i.e. separation of read gap shield layers) while forming the magnetoresistive (MR) read-write heads with attenuated electrical leakage (i.e. electrical shorts through thin dielectric layers separating conductor layers within the magnetoresistive (MR) read-write heads) to provide fully functional magnetoresistive (MR) read-write heads with enhanced reliability.
It is thus towards the goal of forming fully functional and reliable magnetoresistive (MR) read-write heads with attenuated read gap thicknesses that the present invention is directed.
Various methods and resultant magnetic head structures have been disclosed in the art of magnetic head fabrication for forming magnetic heads with enhanced functionality and reliability.
For example, Gill, in U.S. Pat. No. 5,467,881 discloses a method for fabricating a magnetoresistive (MR) read head with attenuated patterned conductor lead layer to shield layer electrical leakage at an air bearing surface (ABS) of the magnetoresistive (MR) read head. The method employs a patterned photoresist strip layer masking of a trackwidth of a magnetoresistive (MR) layer and co-extensive widths of adjoining layers within the magnetoresistive (MR) read head at an air bearing surface (ABS) of the magnetoresistive (MR) read head, followed by a reactive ion etch (RIE) etchback of unmasked portions of the air bearing surface (ABS) to remove conductor residues which bridge between the patterned conductor lead layers and the shield layers within the magnetoresistive (MR) read head.
In addition, Jennison, in U.S. Pat. No. 5,658,469, discloses a method for forming a re-entrant profiled patterned photoresist which may be employed as a lift-off mask for use in fabricating magnetoresistive (MR) sensor elements for use in magnetoresistive (MR) read heads. The re-entrant profiled patterned photoresist layer is formed from a straight sided patterned photoresist layer an upper portion of which is rendered insoluble with respect to a photoresist developer incident to a first electron beam exposure of the straight sided patterned photoresist layer and a lower portion of which is rendered soluble with respect to the photoresist developer solution incident to a second electron beam exposure of the straight sided patterned photoresist layer. The straight sided patterned photoresist layer is then developed with the photoresist developer solution to form the re-entrant profiled patterned photoresist layer.
Finally, Huang et al., in U.S. Pat. No. 5,721,008, discloses a method for controlling patterned magnetoresistive (MR) layer to patterned magnetoresistive (MR) layer overlay alignment within a dual stripe magnetoresistive (DSMR) sensor element which may be employed within a dual stripe magnetoresistive (MR) head. Within the method there is sequentially patterned, while employing a single patterned photoresist layer, a blanket first magnetoresistive (MR) layer having formed thereupon a blanket dielectric spacer layer in turn having formed thereupon a blanket second magnetoresistive (MR) layer to form a fully aligned patterned first magnetoresistive (MR) layer having formed thereupon a patterned dielectric spacer layer in turn having formed thereupon a patterned second magnetoresistive (MR) layer.
Desirable within the art of magnetoresistive (MR) sensor element fabrication are additional methods, and resulting magnetoresistive (MR) sensor element fabrications, which simultaneously provide fully functional and reliable magnetoresistive (MR) sensor elements with attenuated electrical leakage and attenuated read gap thickness.
It is towards providing magnetoresistive (MR) sensor elements in accord with the foregoing goals that the present invention is directed
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method for forming a magnetoresistive (MR) sensor element, and a magnetoresistive (MR) sensor element resulting from the method.
A second object of the present invention is to provide a method and resulting magnetoresistive (MR) sensor element in accord with the first object of the present invention, where the magnetoresistive (MR) sensor element is formed with attenuated electrical leakage and with an attenuated read gap thickness.
A third object of the present invention is to provide a method, and resultant magnetoresistive (MR) sensor element, in accord with the first object of the present invention and the second object of the present invention, which method by which the magnetoresistive (MR) sensor element is fabricated is readily commercially implemented.
In accord with the objects of the present invention, there is provided a method for forming a magnetoresistive (MR) sensor element, and a magnetoresistive (MR) sensor element which may be fabricated employing the method. To practice the method of the present invention, there is first provided a substrate. There is then formed over the substrate a first shield layer. There is then formed upon the first shield layer a first dielectric spacer layer. There is then formed upon the first dielectric spacer
Chen Mao-Min
Han Cherng-Chyi
Horng Cheng T.
Ackerman Stephen B.
Headway Technologies Inc.
Letscher George J.
Saile George O.
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