Method of fabricating a magnetic transducer with a write...

Details Method of fabricating a magnetic transducer with a write... Method of fabricating a magnetic transducer with a write...

2002-10-23

2004-10-19

Tugbang, A. Dexter (Department: 3729)

Metal working

Method of mechanical manufacture

Electrical device making

C029S603230, C029S603250, C029S603160, C029S603180, C216S022000, C216S047000, C216S048000, C216S087000, C360S119050, C360S122000, C360S123090

Reexamination Certificate

active

06804879

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to the field of magnetic transducers (heads) having inductive write heads and more particularly to the structure of and the process for making the pole pieces and coils for the inductive write head.
BACKGROUND OF THE INVENTION
A typical prior art disk system
10
is illustrated in FIG.
1
. In operation the magnetic transducer
20
, usually called a “head” is attached to an arm or actuator
13
and flies above the rotating disk
16
. A voice coil motor
19
(VCM) pivots the actuator
13
to position the magnetic transducer
20
over selected circumferential tracks on the disk
16
. The disk
16
is attached to spindle
18
that is rotated by a spindle motor (not shown). The disk
16
comprises a substrate on which a plurality of thin films are deposited. The thin films include ferromagnetic material that is used to record the magnetic transitions written by the magnetic transducer
20
in which information is encoded. A tape based storage system (not shown) uses a magnetic transducer in essentially the same way as a disk drive, with the moving tape being used in place of the rotating disk
16
.
The magnetic transducer
20
is composed of elements that perform the task of writing magnetic transitions (the write head
23
) and reading the magnetic transitions (the read head
12
) as illustrated in FIG.
2
. The electrical signals to and from the read and write heads
12
,
23
travel along conductive paths (leads) (not shown) which are attached to or embedded in the actuator
13
. Typically there are two leads each
14
for the read and write heads
12
,
23
.
FIG. 2
is a midline section of one type of prior art magnetic transducer
20
A. The components of the read head
12
are the first shield (S
1
), two insulation layers
107
,
109
which surround the sensor element
105
and the second shield
104
(P
1
/S
2
). This type of magnetic transducer
20
A is called a “merged head” because the P
1
/S
2
layer
104
serves as a shield for the read head
12
and a pole piece for the write head
23
A. The yoke also includes a second pole piece
103
(P
2
) which connects with P
1
/S
2
104
away from the air-bearing surface (ABS) at what is sometimes called the “back gap” (BG). The P
2
103
confronts the P
1
104
across the write gap layer
42
to form the write gap
43
at the ABS. The coil
37
in this particular prior art head is deposited on a layer of resist
106
which is used to define the zero throat height (ZTH) by forming a step on the gap layer
42
.
FIG. 3
is a midline section of a second type of prior art magnetic transducer
20
B. There are two significant differences between the magnetic transducers
20
A and
20
B in
FIGS. 2 and 3
. One difference is that the yoke in magnetic transducer
20
B includes three pole pieces P
1
104
, P
2
103
A and P
3
103
B. The P
2
103
A is formed at the write gap
43
a separate element. The third pole piece
103
B (P
3
) is stitched to P
2
103
A and is connected to the P
1
104
at the back gap (BG) to complete the yoke. Typically write heads
23
only have one coil layer
37
, but the particular write head
23
B shown has two coil layers which be called coil
1
37
and coil
2
57
. The turns of both coil
1
and coil
2
are routed between the write gap
43
and the back gap (BG) and then around behind the yoke. Coil
1
and coil
2
are connected electrically (typically behind the back gap) to form a single inductive coil. The P
3
103
B arches over the resist mound
111
which surrounds the coil(s). In either of the prior art write heads
23
A,
23
B the angle at which the bottom surface of P
2
moves away from the ZTH point is typically far less than 90 degrees which results in efficiency losses through flux leakage.
In either of the prior art heads
20
A,
20
B of
FIGS. 2 and 3
additional coil layers can formed on top of the previous coils prior to forming the enclosing pole piece. Thus, three or more coil layers can be made within these basic designs. Adding additional coil layers, however, will not change the fundamental limitations on the yoke lengths in these heads.
As the required recording densities increase the width of the written track must decrease. The needed write heads must have high magnetic efficiency and low inductance. These requirements make it necessary to place the inductive components ever closer to the pole tips than is possible using the prior art.
In U.S. Pat. No. 6,194,323 to Downey and Yen, a process for making semiconductors is disclosed that uses a so-called hard mask. The hard mask is selected to be more resistant to the metal etchant being used, which in turn allows a thinner photoresist to be used with a resulting increase in resolution. The hard mask is deposited on the metal layer and a thin photoresist is deposited on the hard mask and patterned in the convention manner. The hard mask is then etched to expose portions of the metal layer that can then be etched to achieve the desired pattern of metal. The materials useful for the hard mask are said to include titanium nitride, silicon nitride, tungsten, titanium, various glasses, tantalum oxide, aluminum oxide, titanium oxide, as well as, organic hard masks such as spin-on anti-reflection coatings.
One process for forming a pattern of material with submicron dimensions is called the damascene process. In this method the pattern is developed by etching away selected dielectric material to form features (vias, troughs, etc.) that are then overfilled by electroplating a metal such as copper. The overfill is removed by chemical-mechanical polishing (CMP) leaving the metal and dielectric material forming the pattern. Hard masks have been used to improve the precision of the damascene process. In U.S. Pat. No. 6,121,150 Avanzino and Wang suggest use of sputter-resistant materials for the hard mask. Specifically, they teach the use of high atomic mass metallic materials such Ta, W, Ti, TaN, WN and TiN for the hard mask in a damascene process for fabricating semiconductors.
SUMMARY OF THE INVENTION
Applicants disclose a method for producing a magnetic transducer with a inductive write head having a multilayer coil with a high aspect ratio and a short yoke. A damascene process is used for two coil layers and a conventional process for the third coil layer. The process of the invention allows a seed layer for the coil to be deposited on the side walls of the trenches for the first and second coil layers. In one embodiment the seed layer for the coil is preceded by an adhesion layer.
In a preferred embodiment of the invention the first coil layer is formed below the gap layer and behind a pedestal pole piece for P
1
. A layer of polymeric material is deposited to serve as the bed for the turns of the coil. A layer stack including a hard mask layer followed by a masked photoresist layer defines the coil shape and enables etching (RIE) with a high aspect ratio. Tantalum oxide is preferred as the hard mask material. A seed layer is then deposited over the resulting trenches. This process results in the seed layer being deposited on the sidewalls as well as the bottoms of the trenches. In an alternate embodiment an adhesion layer may be deposited prior to the deposition of the seed layer. Tantalum is the preferred adhesion layer and copper is the preferred seed layer for the coil. A wet electroplating process is preferred to deposit the conductive material for the coil on the wafer to overfill the trenches. The first coil layer is completed when the overfill is removed by planarization. The gap layer is then formed. The second layer of the coil is formed above the gap layer and behind the P
2
pole piece using the same method as was used for the first coil layer. The third coil layer may then be formed by a conventional process. The write head is completed with the formation of the P
3
pole piece to complete the yoke.


REFERENCES:
patent: 4110114 (1978-08-01), Sato
patent: 4336316 (1982-06-01), Sato
patent: 5936814 (1999-08-01), Slade et al.
patent: 6018862 (2000-02-01), Stageberg et al.
patent: 6121150 (2000-09-01), Av

Affiliated with

Also associated with

Rating

Method of fabricating a magnetic transducer with a write... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of fabricating a magnetic transducer with a write..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of fabricating a magnetic transducer with a write... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3266056