Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2001-08-20
2004-11-30
Ometz, David (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S316000
Reexamination Certificate
active
06826020
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to thin film magnetic heads used to read and write information to a magnetic storage medium and, more particularly, to a merged-pole magnetic head having inverted write elements.
2. Background Art
Multi-channel magnetic heads are used in tape drives to read and write information to a magnetic tape while the tape travels in both directions relative to the head. Known head designs use thin film processes such as micro-lithography, evaporation, sputtering, ion milling, electroplating, and wet etching to produce magnetic micro-structures on one side of a substrate such as SiC, AlTiC, and ferrite. For example, a number of head architectures use thin film technology to pattern write and read elements onto a substrate, which are then subsequently machined into head bumps and glued together to align the write and read elements for bi-directional tape motion.
FIG. 1
illustrates an example of a “two bump” magnetic head
10
formed in this manner, and
FIG. 2
illustrates an example of a “three bump” magnetic head
20
. An “R” is used to denote a read element, and a “W” is used to denote a write element, and respective gap lines are shown as dashed lines
12
.
In order to write information onto a tape, read elements must be located so as to follow the track on the tape being recorded by the write elements. This is known as a read-back check and is used to ensure integrity of information written to the tape. Thus, write and read elements operate simultaneously. Unfortunately, the read channel detects unwanted noise from the write channel, which is commonly referred to as feed through. For this reason, write and read elements are kept separated from each other by a spacing denoted “d”.
In addition to the spacing requirement, each read element (R) must be precisely aligned with a corresponding write element (W) as shown by the dashed line a—a, i.e., the “bump-to-bump” alignment. Proper alignment is essential in order to enable the head to be capable of “read-while-write” (RWW) operation to verify that the information has been written to the tape correctly as the tape is spooled through the head.
It is anticipated that future storage media such as tape will attain storage capacities in excess of 1 terabyte of information. Such a high storage capacity places significant demands on tape drives and will be achieved, in part, through a significant increase in track densities of the tape. This increase in track density means that not only will the multi-channel recording head have to write and read narrow track widths, but also that the servo system must correctly align the head relative to the tape during both read and write operations. This necessitates that the tape drive meet track mis-registration requirements, which includes, among other factors, the read and write width tolerances and head and tape dimension tolerances. As track densities are increased, all head designs require increasingly stringent alignment between the write and read elements in both the forward and reverse directions, i.e., the bump-to-bump alignment.
FIG. 3
illustrates a block diagram of a conventional two bump head
30
having a merged-pole read/write element structure. Head
30
meets some of the demands placed by increased track densities. Head
30
includes two modules
32
and
34
positioned back-to-back with respect to each other. Each module
32
and
34
includes a substrate
36
and a merged-pole read/write structure facing outwards. Each merged-pole read/write structure includes a read element
38
positioned on substrate
36
and a write element having a wide top write pole
40
and a bottom write pole
42
. Wide top write pole
40
is used to write information to tape. In operation, information is written by top write pole
40
of module
32
and then read verified using read element
38
of module
34
in a first tape direction indicated in FIG.
3
. Similarly, information is written by top write pole
40
of module
34
and then read verified using read element
38
of module
32
in the opposite tape direction.
A problem with conventional two-bump head
30
with its merged-pole read/write structure is that significant offset between the width of wide top write pole
40
and the width of the track of the tape occurs. This is exacerbated for narrow track widths and, depending on tape media type, substantial erased zones at each edge of the track are formed. Both of these factors can greatly limit the head width tolerance impacting the TMR budget.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a merged-pole magnetic head having inverted write elements.
It is another object of the present invention to provide a magnetic head having a merged-pole read/write element structure with inverted write elements.
It is a further object of the present invention to provide a merged-pole multiple bump magnetic head having inverted write elements.
It is still another object of the present invention to provide a merged-pole magnetic head having write elements in which an inverted pole is used to write information.
In carrying out the above objects and other objects, the present invention provides a magnetic head for writing and reading data on a tape. The magnetic head includes first and second substrates each having first and second surfaces. The first surfaces of each substrate being connected with each other, the second surfaces of each substrate having a read element and an inverted write element. Each read element being formed over the second surface of each substrate and each inverted write element is formed over a respective read element.
Each inverted write element includes a write gap in a zero throat region and a top write pole disposed adjoining the write gap in the zero throat region. The top write pole has a top write pole width in the zero throat region. A bottom write pole is disposed adjoining the write gap in the zero throat region on a side of the write gap opposite the top write pole. The bottom write pole has an upper portion adjoining the write gap and a lower portion. The upper portion having an upper portion width in the zero throat region. The lower portion having a lower portion width in the zero throat region. The lower portion width being greater than the upper portion width and smaller than the top write pole width.
The write gap has a write gap thickness and the upper portion of the bottom write pole has an upper portion thickness. The write gap and the upper portion of the bottom write pole may be arranged so that the upper portion thickness is at least twice the write gap thickness.
Each inverted write element may further include a base disposed adjacent the bottom write pole on a side opposite the write gap, and a planarization layer disposed between the base and the write gap. Each inverted write element may further include a coil disposed adjoining the write gap on a same side of the write gap as the top write pole.
Further, in carrying out the above objects and other objects, the present invention provides a method of fabricating a magnetic head. The method includes forming a read element on a first surface of respective first and second substrates. A bottom write pole is then formed over each read element. Each bottom write pole has an upper portion and a lower portion in a zero throat region. A write gap is then formed overlaying each bottom write pole and a top write pole is formed overlaying each write gap. Each top write pole has a top pole width in the zero throat region that is greater than the lower portion width of the respective bottom write pole. Second surfaces of the first and second substrates together are then connected together.
Forming each bottom write pole may include depositing a bottom write pole layer, patterning the bottom write pole layer to define the upper portion of the bottom write pole disposed on a remainder layer, and patterning the remainder layer to define the lower portion of the bottom write pole.
Alternatively, f
Daby Larry E.
Watson Mark Lee
Brooks & Kushman P.C.
Ometz David
Storage Technology Corporation
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