Planar perpendicular recording head

#The invention relates to magnetic thin film heads for perpendicular recording and more particularly to magnetic pole pieces and shields used in such heads and to storage devices using such heads.

#In a typical prior art magnetic disk recording system a slider containing magnetic transducers for reading and writing magnetic transitions is supported by a suspension as it flies above the disk that is being rotated by a spindle motor. The disk includes a plurality of thin films and at least one ferromagnetic thin film in which the recording (write) head records the magnetic transitions in which information is encoded. The magnetic domains in the media on can be written longitudinally or perpendicularly. The read and write head portions of the slider are built-up in layers using thin film processing techniques. Typically the read head is formed first, but the write head can also be fabricated first. The conventional write head is inductive and the read sensor is magnetoresistive.

#In a disk drive using perpendicular recording the recording head is designed to direct magnetic flux through the recording layer in a direction which is perpendicular to the plane of the disk. Typically the disk for perpendicular recording has a hard magnetic recording layer and a magnetically soft underlayer. During recording operations using a single-pole type head, magnetic flux is directed from the main pole of the recording head perpendicularly through the hard magnetic recording layer, then into the plane of the soft underlayer and back to the return pole in the recording head. The shape and size of the main pole piece and associated shields are the primary factors in determining the track width.

#FIG. 1 is an isometric illustration of selected components of a head according to an embodiment of the invention.

#FIG. 2(a) illustrates a midline section, perpendicular to the wafer surface, of a write head with a trailing shield according to an embodiment of the invention.

#FIG. 2(b) illustrates the relationships of the components of the head shown in FIG. 2(a) viewed from the wafer surface which is also the ABS.

#The various embodiments of heads described herein require no lapping. In order to implement this head design, the write head and the read head must be integrated into a fabrication process in which the wafer surface and the thin film layers in a head according to the invention are parallel to the ABS. In the prior art method of fabricating heads the thin films are deposited on the surface of the wafer and are, of course, parallel to the wafer surface, but the wafer, along with the thin films, is cut to expose the edges of the thin film layers. The prior art ABS processing, including lapping, is performed on the exposed edges and the final ABS is oriented perpendicular to the plane of the thin films. In contrast, the ABS is on top of the wafer according to the invention and the cuts made to separate the head from the plurality of other heads on the wafer are made in nonfunctional material on four sides perpendicular to the ABS as illustrated in FIG. 7. Wafer 17 is shown after a plurality of heads (or sliders) 20 have been deposited on the wafer surface. The line labeled M represents a cut in the wafer 17 made to separate the heads 20 from wafer 17. Lines K, J, P, Q, R and S mark future cut lines. Each of the heads 20 have a read head 30 and a write head 40 fabricated parallel to the ABS which is also the upper surface of the wafer 17. The elements in FIG. 7 are not to scale, since the actual sizes of the read and write heads 30, 40 are much smaller than shown in relation the head 20 as will be clear to those skilled in the art. The position of the read and write heads 30, 40 on the head 20 is also not representative. Preferably the read and write heads 30, 40 will be located very near the edge which will be the trailing edge of the head 20 when installed in the magnetic storage device. Since lapping is not required in a process according to the invention, critical alignment of the read head to the write head in the “z” direction is not required. The need to align in the “z” direction is reduced since the critical structures are formed by deposition thicknesses rather than mechanical removal of material. However, with all heads, the centerline placement of the read sensor relative to the center line placement of the write gap does rely on alignment and this is accomplished with lithography. In the prior art scheme, read to write head alignment in the “z” direction was required since the end of lapping determines the final stripe height of the read sensor, as well as, critical dimensions in the write head. In heads for perpendicular recording, however, the prior art ABS processing is even less effective in forming precise dimensions simultaneously in the read sensor and the write head. For example, in some perpendicular head designs, the top of the read sensor must be referenced to the top of the trailing shield type of return pole piece and lapping simultaneously reduces the thickness of the trailing shield and the stripe height making it difficult to precisely control both dimensions. In a process according to the invention the planarization of the ABS including the top of a trailing shield and a read sensor can be accomplished with a simple planarization step, e.g. chemical-mechanical planarization (CMP) and the trailing shield and sensor thickness are determined by deposition of thin films rather than lapping. In addition, the invention allows for the fabrication of simple single pole heads with the shape of the pole tip formed by ion milling and lithography.

#The advantages of building a perpendicular recording head with return pole piece or shield formed parallel to the ABS (i.e. incorporating a head design with the ABS parallel to the wafer processing surfaces) include:

#1. control of the shield and sensor thickness is determined by deposition rather than lapping.