Magnetic thin film media with a pre-seed layer of CrTi

Details Magnetic thin film media with a pre-seed layer of CrTi Magnetic thin film media with a pre-seed layer of CrTi

2001-03-02

2003-07-15

Rickman, Holly (Department: 1773)

Stock material or miscellaneous articles

All metal or with adjacent metals

Having magnetic properties, or preformed fiber orientation...

C428S663000, C428S668000, C428S666000, C428S336000, C428S900000, C428S690000

Reexamination Certificate

active

06593009

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to magnetic thin film media and methods for their fabrication and more particularly to magnetic thin film disks having a pre-seed layer and a seed layer prior to an underlayer.
BACKGROUND OF THE INVENTION
A typical prior art head and disk system
10
is illustrated in FIG.
1
. In operation the magnetic transducer
20
is supported by the suspension
13
as it flies above the disk
16
. The magnetic transducer
20
, usually called a “head” or “slider,” 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
). The electrical signals to and from the read and write heads
12
,
23
travel along conductive paths (leads)
14
which are attached to or embedded in the suspension
13
. The magnetic transducer
20
is positioned over points at varying radial distances from the center of the disk
16
to read and write circular tracks (not shown). The disk
16
is attached to a spindle
18
that is driven by a spindle motor
24
to rotate the disk
16
. The disk
16
comprises a substrate
26
on which a plurality of thin films
21
are deposited. The thin films
21
include ferromagnetic material in which the write head
23
records the magnetic transitions in which information is encoded.
The conventional disk
16
consists substrate
26
of AlMg with an electroless coating of NiP which has been highly polished. The thin films
21
on the disk
16
typically include a chromium or chromium alloy underlayer which is deposited on the substrate
26
. The ferromagnetic layer in the thin films is based on various alloys of cobalt, nickel and iron. For example, a commonly used alloy is CoPtCr. Additional elements such as tantalum and boron are often used in the magnetic alloy. A protective overcoat layer is used to improve wearability and corrosion. The three film disk described above does not exhaust the possibilities. Various seed layers, multiple underlayers and laminated magnetic films have all been described in the prior art.
In particular, seed layers have been suggested for use with nonmetallic substrate materials such as glass. Typically the seed layer is a relatively thin layer which is the initial film deposited on the substrate and is followed by the underlayer. Materials proposed for use as seed layers include chromium, titanium, tantalum, Ni3P, MgO, carbon, tungsten, AlN, FeAl and NiAl. In U.S. Pat. No. 5,789,056 to Bian, et al., the use of a CrTi seed layer is described. The underlayers mentioned are Cr, CrV and CrTi.
SUMMARY OF THE INVENTION
The applicants disclose a thin film magnetic media structure with a pre-seed layer of CrTi. The CrTi pre-seed layer presents an amorphous or nanocrystalline structure. The preferred seed layer is RuAl. The use of the CrTi/RuAl bilayer structure provides superior adhesion to the substrate and resistance to scratching, as well as, excellent coercivity and signal-to-noise ratio (SNR) and reduced cost over the prior art.


REFERENCES:
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T.P.Nolan, et al., “Independent Optimization of Nucleation and Growth Processes of Titanium-alloy Underlayers for Cobalt-alloy Perpendicular Recording Media,” Materials Research Soc. Symp. Process. vol. 403, 1996, pp. 713ff.
T.Kanbe,et al., “Effects of underlayer grain size on the microstructure of the magnetic layer in CoCrPt media,” IEEE Transactions on Magnetics, vol. 35, No. 5, Sep. 1999, pp. 2667ff.
M.Mirzamaani, et al., “Recording Performance of Thin Film Media With Various Crystallographic Preferred Orientations on Glass Substrates,” IEEE Transactions on Magnetics, vol. 34, No. 4, Jul. 1998, pp. 1588ff.
L.Lee, et al., “Seed layer induced (002) crystallographic texture in NiAl underlayers,” J. Appl. Physical. 79(8). Apr. 15, 1996.

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