Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
1995-09-29
2002-03-19
Nguyen, Nam (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192150
Reexamination Certificate
active
06358379
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming a magneto-resistance effect film (MR film) used in a magneto-resistance effect (MR) type magnetic head, for example.
It is customary that an MR film forming an MR type magnetic head or the like is formed of an Ni—Fe alloy film.
Also, it is customary that, when the MR film is formed of the Ni—Fe alloy, the MR film is formed by the application of vacuum evaporation or sputtering using the Ni—Fe alloy as an evaporation source or a target
These vacuum evaporation and sputtering, however, have disadvantages in forming a film. Specifically, it is difficult for the vacuum evaporation to control a film thickness of the MR film. Therefore, the vacuum evaporation is not suitable for reducing a film thickness of the MT film. The sputtering, on the other hand, has the problem that a magneto-resistance changing ratio thereof is small as compared with that of the vacuum evaporation.
The Ni—Fe alloy film is fundamentally small in magneto-resistance changing ratio. Specifically, a magneto-resistance changing ratio obtained under restrictions that the Ni—Fe alloy film is actually applied to a magnetic head is 2% at maximum. In general, a magneto-resistance changing ratio of the Ni—Fe alloy film falls in a range of about 1.5 to 1.6%.
FIG. 1
of the accompanying drawings schematically shows a front view of a magnetic gap portion of an MR type magnetic head which carries out magnetic recording and reproduction. As shown in
FIG. 1
, when an MR element
3
forming an MR type reproducing head is disposed within a magnetic gap G formed in recording magnetic head cores/magnetic shield cores
2
in an opposing relation to a magnetic recording medium
1
, the magnetic gap G is requested to be reduced in width in order to enhance a recording density. Therefore, it is requested that the MR element, i.e., the MR film is reduced in thickness much more. If however the MR film is reduced in thickness as described above, then the magneto-resistance changing ratio is lowered much more, which causes a trouble in actual practice.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of forming a magneto-resistance effect thin film (MR film) in which the MR film of a high magneto-resistance changing ratio and of a small film thickness can reliably and stably be obtained with excellent reproducibility and with high productivity.
According to the present invention, there is provided a method of forming a magneto-resistance effect thin film in which a single unit layer of an Ni—Fe alloy thin film layer or superlattice thin film layer of Ni and Fe is formed as a unit layer or a plurality of said unit layers are laminated by sputtering Ni and Fe on a base material from an Ni target and an Fe target disposed separately while the Ni target and the Fe target are both being rotated relatively to the base material.
Further, according to the present invention, the unit layer has a thickness of 10 Å or smaller.
Furthermore, according to the present invention, an amount of Ni in a composition of the whole of the magneto-resistance film formed of the Ni—Fe alloy thin film layer or the superlattice layer of Ni and Fe is selected in a range of from 75 to 90 weight %.
REFERENCES:
patent: 4260466 (1981-04-01), Shirahata et al.
patent: 4576699 (1986-03-01), Sato et al.
patent: 4824724 (1989-04-01), Ueda et al.
patent: 4929320 (1990-05-01), Yamada et al.
patent: 4940511 (1990-07-01), Fontana, Jr. et al.
patent: 5505834 (1996-04-01), Chaug et al.
Nguyen Nam
Sonnenschein Nath & Rosenthal
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