U.S. patent application number 10/449034 was filed with the patent office on 2003-11-13 for film and method for producing the same.
Invention is credited to Hiramoto, Masayoshi, Matsukawa, Nozomu, Sakakima, Hiroshi.
Application Number | 20030211360 10/449034 |
Document ID | / |
Family ID | 17191875 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030211360 |
Kind Code |
A1 |
Hiramoto, Masayoshi ; et
al. |
November 13, 2003 |
Film and method for producing the same
Abstract
Magnetic film comprising a substantially crystalline magnetic
layer and an intermediate layer alternately formed in contact with
each other, wherein the magnetic layer has composition
(M.sub.1.alpha..sub.1.beta..sub.1).sub-
.100-.delta.1A.sub.1.delta..sub.1 (.alpha..sub.1, .beta..sub.1, and
.delta..sub.1 represent % by atomic weight; M.sub.1 is at least one
of Fe, Co, and Ni; X.sub.1 is at least one of Mg, Ca, Sr, Ba, Si,
Ge, Sn, Al, Ga, and transition metals excluding M.sub.1; and
A.sub.1 is at least one of 0 and N), wherein:
0.1.ltoreq..beta..sub.1.ltoreq.12 .alpha..sub.1+.beta..sub.1=100
0<.delta..sub.1.ltoreq.10; the intermediate layer has
composition (M.sub.2.alpha..sub.2X.sub.2.beta..-
sub.2).sub.100-.delta.2A.sub.2.delta..sub.2 (.alpha..sub.2,
.beta..sub.2, and .delta..sub.2 represent % by atomic weight,
M.sub.2 is at least one of Fe, Co, and Ni; X.sub.2 is at least one
of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, Ge and transition metals
excluding the M.sub.2; and A.sub.2 is 0), wherein:
0.1.ltoreq..beta..sub.2.ltoreq.80 .alpha..sub.2+.beta..sub.2=100
.delta..sub.1.ltoreq..delta..sub.2.ltoreq.67.
Inventors: |
Hiramoto, Masayoshi; (Nara,
JP) ; Matsukawa, Nozomu; (Nara, JP) ;
Sakakima, Hiroshi; (Kyoto, JP) |
Correspondence
Address: |
Thomas W. Adams
Renner, Otto, Boisselle & Sklar, LLP
Nineteenth Floor
1621 Euclid Avenue
Cleveland
OH
44115
US
|
Family ID: |
17191875 |
Appl. No.: |
10/449034 |
Filed: |
May 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10449034 |
May 30, 2003 |
|
|
|
09387404 |
Sep 2, 1999 |
|
|
|
Current U.S.
Class: |
360/125.63 ;
360/119.07; 360/125.5; 428/336; 428/815.2; G9B/5.08; G9B/5.116 |
Current CPC
Class: |
B32B 15/01 20130101;
Y10T 428/12611 20150115; C22C 38/12 20130101; G11B 5/187 20130101;
G11B 5/3903 20130101; C22C 38/06 20130101; Y10T 428/12576 20150115;
B82Y 25/00 20130101; G11B 5/3109 20130101; G11B 5/3153 20130101;
G11B 5/11 20130101; Y10T 428/265 20150115; H01F 10/32 20130101;
C22C 45/02 20130101; C23C 14/0073 20130101; C23C 14/185 20130101;
C22C 38/001 20130101; G11B 5/012 20130101; B32B 15/011 20130101;
G11B 5/3967 20130101; C22C 38/18 20130101; Y10T 428/1186 20150115;
C22C 38/14 20130101; H01F 10/16 20130101; C22C 38/02 20130101 |
Class at
Publication: |
428/692 ;
360/126; 428/336 |
International
Class: |
B32B 009/00; G11B
005/147 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 3, 1998 |
JP |
10-249360 |
Claims
What is claimed is:
1. A method for producing a high-resistant layer, comprising the
steps of: forming a low-resistant layer containing 10% by atomic
weight or more of at least one element selected from the group
consisting of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and transition
metals excluding at least one magnetic metal selected from the
group consisting of Fe, Co, and Ni on either one of a magnetic thin
film and a magnetic layer; and oxidizing or nitriding the
low-resistant layer in an atmosphere selected from the group
consisting of oxygen, nitrogen, oxygen plasma, and nitrogen
plasma.
2. A method for producing a high-resistant layer according to claim
1, wherein the magnetic thin film or the magnetic layer contains an
element compatible with oxygen.
3. A magnetic multilayer comprising a magnetic thin film and a
high-resistant layer alternately formed, wherein assuming that an
average thickness of the magnetic thin film is T.sub.3, and an
average thickness of the high-resistant layer is T.sub.4, the
following expressions are satisfied: 100
nm.ltoreq.T.sub.3.ltoreq.1000 nm 2 nm.ltoreq.T.sub.4.ltore- q.50 nm
10.ltoreq.T.sub.3/T.sub.4.ltoreq.500
4. A thin film head comprising an upper magnetic pole and a lower
magnetic pole, wherein the upper magnetic pole includes either one
of a high-resistant magnetic film and a magnetic multilayer with
high resistivity, having a specific resistance of 80 .mu..OMEGA.cm
or more, and either one of a magnetic thin film and a magnetic
multilayer, the upper magnetic pole and the lower magnetic pole
form a recording gap, and either one of the magnetic thin film and
the magnetic multilayer is formed at least in the vicinity of the
recording gap at an end of the upper magnetic pole.
5. A thin film head according to claim 4, wherein either one of the
magnetic thin film and the magnetic multilayer is formed at least
in the recording gap, and either one of the high-resistant magnetic
film and the magnetic multilayer with high resistivity having a
specific resistance of 80 .mu..OMEGA.cm or more is formed on either
one of the magnetic thin film and the magnetic multilayer.
6. A method for producing a thin film, comprising: a first step of
moving a substrate onto which a film is formed and a source for
supplying material for forming a film in a relative manner; and a
second step of forming at least one of a magnetic thin film, a
magnetic multilayer, a high-resistant magnetic film, and a magnetic
multilayer with high resistivity, wherein at least one
magnetization difficult axis of the magnetic thin film, the
magnetic multilayer, the high-resistant magnetic film, and the
magnetic multilayer is formed in a movement direction in which the
substrate and the source are moved in a relative manner.
7. A method for producing a thin film according to claim 6, wherein
the movement direction includes a depth direction of an upper
magnetic pole of a thin film head.
8. A method for producing a thin film according to claim 6, wherein
the first step includes forming a film by a vapor growth method for
generating a magnetic field of 50 Oe or more which is substantially
orthogonal to the movement direction, substantially parallel to a
film formation surface on the substrate, substantially uniform, and
substantially in one direction.
9. A method for producing a thin film according to claim 6, wherein
the first step includes forming a film by changing a concentration
of oxygen, oxygen plasma, nitrogen, or nitrogen plasma in a vapor
growth apparatus.
10. A method for producing a thin film according to claim 6,
wherein a temperature of the substrate during formation of a film
is substantially 300.degree. C. or less.
11. A hard disk drive using the magnetic multilayer of claim 3 as a
magnetic pole.
12. A hard disk drive using the magnetic multilayer of claim 3 as a
part of a shield.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a magnetic film having a
high saturated magnetic flux density used in a recording head and a
magnetic reproducing head of a hard disk drive (HDD), a magnetic
sensor such as a magnetic impedance sensor, and a magnetic circuit
component such as a magnetic coil and an inductor; a method for
producing the magnetic film; and a thin film head using the
magnetic film.
[0003] 2. Description of the Related Art
[0004] In recent years, the maximum recording frequency of HDDs has
remarkably increased to about 200 MHz. Furthermore, high-density
recording media are likely to have a high coercivity. Therefore,
there has been a demand for a recording head material which has a
high effective magnetic permeability even at a high frequency and
in which a magnetic pole is unlikely to be saturated (i.e., a
recording head material which has a high resistivity (high .rho.),
strong uniaxial anisotropy, and a high saturated magnetic flux
density (high Bs)).
[0005] In order to satisfy the above-mentioned demand, F-N type
material such as FeCrN (J. Appl. Phy. 81(8), 15, April 1997) and
FeRhN (IEEE Trans. Magn. VVOl 133. No. 5, 1997) formed by
sputtering has been reported as a materiel, for example, with Bs of
2T (tesla) or more.
[0006] The above-mentioned material with high Bs has a low
resistivity; therefore, it is difficult to use such material at a
high frequency. However, it has been reported that such material is
used with a non-magnetic insulator (Al.sub.2O.sub.3, SiO.sub.2,
etc.) so as to suppress an eddy current loss (The Japan Society of
Applied Magnetics, document of The 103th Research Institute, p. 2,
1998).
[0007] As shown in FIG. 40, U.S. Pat. Nos. 5,543,989 and 5,686,193
disclose a magnetic film with magnetic pole end regions 119 and
123, including a layered structure of a seed layer of sendust and a
bulk layer of sendust.
[0008] As material for a single layer with high .rho., Fe-M-O
(M=Hf, Zr) (Summary of the lecture in the 122nd Japan Society of
Metal, p. 179 (424) 1998) is known; however, it has a disadvantage
of low Bs. It is required that the above-mentioned material with
high Bs or high .rho. is capable of providing uniaxial anisotropy
and suppressing a ferromagnetic resonance loss. For this purpose,
heat treatment in a magnetic field or film formation in a magnetic
field is conducted.
[0009] However, even in the case where uniaxial anisotropy is given
to a conventional film with high Bs, a recording magnetic pole used
in a thin film head has an increased aspect ratio between the
thickness and the width of a magnetic pole due to a decreased width
of a track. Therefore, magnetic anisotropy is caused by an
anti-magnetic field in a direction perpendicular to the surface of
a recording gap between an upper magnetic pole and a lower magnetic
pole.
[0010] Because of the above, the direction of a magnetization easy
axis shifts in the direction perpendicular to the film surface,
which complicates a domain structure in the entire magnetic pole.
As a result, magnetic characteristics at a high frequency
degrade.
[0011] Furthermore, in the case where a magnetic pole is formed by
a layered structure including a conventional layer with high Bs and
an insulation resistant layer, it is required that at least two
sources for supplying material are used for forming the layer with
high Bs and the insulation resistant layer, and that these layers
are alternately formed, which results in a longer period of time of
film formation.
[0012] Furthermore, in performing a dry etching technique for
minute processing (i.e., patterning of a magnetic pole), an etching
rate of a magnetic material of transition metal such as Fe, Co, and
Ni is substantially different from that of a non-magnetic
insulating material such as Al.sub.2O.sub.3 and SiO.sub.2. Thus,
for example, in the case where radical etching or reactive ion
etching (RIE) with a high etching rate is conducted, since these
reactions are isotropic, unevenness is formed on cross-sections of
the magnetic layer and the non-magnetic insulating layer.
Furthermore, when reactive gas to be used for each layer is varied,
a processing speed as a whole is decreased due to gas substitution,
and a device becomes complicated.
[0013] Furthermore, in the case where the above-mentioned film is
used in high-frequency recording, a spin valve film is used for a
reproducing head. At least one of the magnetic layers included in
the spin valve film is a fixed layer whose magnetization is fixed
in a direction of medium magnetization, and the direction of fixed
magnetization is orthogonal to the direction of uniaxial anisotropy
required for a recording magnetic pole film for a high
frequency.
[0014] The recording magnetic film which has been conventionally
developed is produced while uniaxial anisotropy is obtained.
Alternatively, after the recording magnetic film is produced,
uniaxial anisotropy is formed by heat treatment in a magnetic
field. Therefore, anisotropy of the recording magnetic film is
weakened due to the heat treatment in a magnetic field conducted
for fixing the fixed layer of the spin valve film in a preferable
direction of the fixed magnetization.
[0015] Furthermore, when an upper magnetic pole is formed, the
quality of a slope portion degrades due to oblique formation.
SUMMARY OF THE INVENTION
[0016] A magnetic film of the present invention includes a magnetic
layer and an intermediate layer alternately formed, wherein the
magnetic layer has a composition represented by
(M.sub.1.alpha..sub.1X.sub.1.beta..sub.1-
).sub.100-.delta..sub.1A.sub.1.delta..sub.1 (where .alpha..sub.1,
.beta..sub.1, and .delta..sub.1 represent % by atomic weight;
M.sub.1 is at least one magnetic metal selected from the group
consisting of Fe, Co, and Ni; X.sub.1 is at least one selected from
the group consisting of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and
transition metals excluding the M.sub.1; and A.sub.1 is at least
one selected from the group consisting of 0 and N), the magnetic
layer has the following composition range:
[0017] 0.1.ltoreq..beta..sub.1.ltoreq.12
[0018] .alpha..sub.1+.beta..sub.1=100
[0019] 0<.delta..sub.1.ltoreq.10
[0020] the intermediate layer has a composition represented by
(M.sub.2.alpha..sub.2X.sub.2.beta..sub.2).sub.100-.delta..sub.2A.sub.2.de-
lta..sub.2 (where .alpha..sub.2, .beta..sub.2, and .delta..sub.2
represent % by atomic weight; M.sub.2 is at least one magnetic
metal selected from the group consisting of Fe, Co, and Ni; X.sub.2
is at least one selected from the group consisting of Mg, Ca, Sr,
Ba, Si, Ge, Sn, Al, Ga, and transition metals excluding the
M.sub.1; and A.sub.2 is at least one selected from the group
consisting of O and N), the intermediate layer has the following
composition range:
[0021] 0.1.ltoreq..beta..sub.2.ltoreq.80
[0022] .alpha..sub.2+.beta..sub.2=100
[0023] .delta..sub.1.ltoreq..delta..sub.2.ltoreq.67
[0024] In one embodiment of the present invention, the X.sub.1
contains at least one selected from the group consisting of Si, Al,
Ti, and V.
[0025] In another embodiment of the present invention,
M.sub.1=M.sub.2 and X.sub.1=X.sub.2.
[0026] In another embodiment of the present invention, A.sub.2
contains O.
[0027] In another embodiment of the present invention, assuming
that an average thickness of the magnetic layer is T.sub.1 and an
average thickness of the intermediate layer is T.sub.2, the
following expressions are satisfied:
[0028] 2 nm.ltoreq.T.sub.1.ltoreq.150 nm
[0029] 0.4 nm.ltoreq.T.sub.2.ltoreq.15 nm
[0030] 1.ltoreq.T.sub.1/T.sub.2.ltoreq.50
[0031] In another embodiment of the present invention, the magnetic
film satisfies the following expressions:
[0032] 20 nm<T.sub.1.ltoreq.150 nm
[0033] 1 nm<T.sub.2.ltoreq.15 nm
[0034] 4.ltoreq.T.sub.1/T.sub.2.ltoreq.50
[0035] at least 50% of magnetic crystal grains included in the
adjacent magnetic layers via the intermediate layer spread across
the intermediate layer.
[0036] A magnetic film of the present invention includes a magnetic
layer and an intermediate layer alternately formed, wherein the
magnetic layer has a composition represented by
(M.sub.1.alpha..sub.1X.sub.1.beta..sub.1-
).sub.100-.delta..sub.1A.sub.1.delta..sub.1 (where .alpha..sub.1,
.beta..sub.1, and .delta..sub.1 represent % by atomic weight,
M.sub.1 is at least one magnetic metal selected from the group
consisting of Fe, Co, and Ni; X.sub.1 is at least one selected from
the group consisting of Mg, Ca, Sr, Ba, Si, Ge, Al, Ga, and
transition metals including a IVa group, a Va group, and Cr; and Al
is at least one selected from the group consisting of O and N), the
magnetic layer has the following composition range:
[0037] 0.1.ltoreq..beta..sub.1.ltoreq.12
[0038] .alpha..sub.1+.beta..sub.1=100
[0039] 0.ltoreq..delta..sub.1.ltoreq.10
[0040] the intermediate layer has a composition represented by
(M.sub.2.alpha..sub.2X.sub.2.beta..sub.2).sub.100-.delta..sub.2A.sub.2.de-
lta..sub.2 (where .alpha..sub.2, .beta..sub.2, and .delta..sub.2
represent % by atomic weight, M.sub.2 is at least one magnetic
metal selected from the group consisting of Fe, Co, and Ni; X.sub.2
is at least one selected from the group consisting of Mg, Ca, Sr,
Ba, Si, Al, Ga, Ge, and transition metals including a IVa group, a
Va group, and Cr; and A.sub.2 is at least one selected from the
group consisting of O and N), the intermediate layer has the
following composition range:
[0041] 0.1.ltoreq..beta..sub.2.ltoreq.80
[0042] .alpha..sub.2+.beta..sub.2=100
[0043] .delta..sub.1<.delta..sub.2.ltoreq.67
[0044] In one embodiment of the present invention, the X.sub.1
contains at least one selected from the group consisting of Si, Al,
Ti, and V.
[0045] In another embodiment of the present invention,
M.sub.1=M.sub.2 and X.sub.1=X.sub.2.
[0046] In another embodiment of the present invention, A.sub.2
contains O.
[0047] In another embodiment of the present invention, assuming
that an average thickness of the magnetic layer is T.sub.1 and an
average thickness of the intermediate layer is T.sub.2, the
following expressions are satisfied:
[0048] 2 nm.ltoreq.T.sub.1.ltoreq.150 nm
[0049] 0.4 nm.ltoreq.T.sub.2.ltoreq.15 nm
[0050] 1.ltoreq.T.sub.1/T.sub.2.ltoreq.50
[0051] In another embodiment of the present invention, the magnetic
film satisfies the following expressions:
[0052] 20 nm<T.sub.1.ltoreq.150 nm
[0053] 1 nm<T.sub.2.ltoreq.15 nm
[0054] 4.ltoreq.T.sub.1/T.sub.2.ltoreq.50
[0055] at least 50% of magnetic crystal grains included in the
adjacent magnetic layers via the intermediate layer spread across
the intermediate layer.
[0056] A magnetic film of the present invention includes a magnetic
layer and an intermediate layer alternately formed, wherein the
magnetic layer has a composition represented by
(M.sub.1.alpha..sub.1X.sub.1.beta..sub.1-
Z.sub.1.gamma..sub.1).sub.100-.delta..sub.1A.sub.1.delta..sub.1
(where .alpha..sub.1, .beta..sub.1, .gamma..sub.1, and
.delta..sub.1 represent % by atomic weight; M.sub.1 is at least one
magnetic metal selected from the group consisting of Fe, Co, and
Ni; X.sub.1 is at least one selected from the group consisting of
Mg, Ca, Sr, Ba, Si, Al, Ga, Ge and transition metals including a
IVa group, a Va group, and Cr; Z.sub.1 is at least one selected
from the group consisting of Zn, Rh, Ru, and Pt; and A.sub.1 is at
least one selected from the group consisting of O and N), the
magnetic layer has the following composition range:
[0057] 0.1.ltoreq..beta..sub.1.ltoreq.12
[0058] 0.1.ltoreq..gamma..sub.1.ltoreq.8
[0059] .alpha..sub.1+.beta..sub.1+.gamma..sub.1=100
[0060] 0.ltoreq..delta..sub.1.ltoreq.10
[0061] the intermediate layer has a composition represented by
(M.sub.2.alpha..sub.2X.sub.2.beta..sub.2Z.sub.2.gamma..sub.2).sub.100-.de-
lta..sub.2A.sub.2.delta..sub.2 (where .alpha..sub.2, .beta..sub.2,
.gamma..sub.2, and .delta..sub.2 represent % by atomic weight,
M.sub.2 is at least one magnetic metal selected from the group
consisting of Fe, Co, and Ni; X.sub.2 is at least one selected from
the group consisting of Mg, Ca, Sr, Ba, Si, Al, Ga, Ge, and
transition metals including a IVa group, a Va group, and Cr:
Z.sub.2 is at least one selected from the group consisting of Rh,
Ru, and Pt; and A.sub.2 is at least one selected from the group
consisting of O and N), the intermediate layer has the following
composition range:
[0062] 0.1.ltoreq..beta..sub.2.ltoreq.80
[0063] 0.1.ltoreq..gamma..sub.2.ltoreq.80
[0064] .alpha..sub.2+.beta..sub.2+.gamma..sub.2=100
[0065] .delta..sub.1<.delta..sub.2.ltoreq.67
[0066] In one embodiment of the present invention, the X.sub.1
contains at least one selected from the group consisting of Si, Al,
Ti, and V.
[0067] In another embodiment of the present invention,
M.sub.1=M.sub.2 and X.sub.1=X.sub.2.
[0068] In another embodiment of the present invention, A.sub.2
contains O.
[0069] In another embodiment of the present invention, assuming
that an average thickness of the magnetic layer is T.sub.1 and an
average thickness of the intermediate layer is T.sub.2, the
following expressions are satisfied:
[0070] 2 nm.ltoreq.T.sub.1.ltoreq.150 nm
[0071] 0.4 nm.ltoreq.T.sub.2.ltoreq.15 nm
[0072] 1.ltoreq.T.sub.1/T.sub.2.ltoreq.50
[0073] In another embodiment of the present invention, the magnetic
film satisfies the following expressions:
[0074] 20 nm<T.sub.1.ltoreq.150 nm
[0075] 1 nm<T.sub.2.ltoreq.15 nm
[0076] 4.ltoreq.T.sub.1/T.sub.2.ltoreq.50
[0077] at least 50% of magnetic crystal grains included in the
adjacent magnetic layers via the intermediate layer spread across
the intermediate layer.
[0078] A high-resistant magnetic film of the present invention has
a composition represented by M.alpha.X.beta. (N.delta.O
.epsilon.).gamma. (where .alpha., .beta., .gamma., .delta., and
.epsilon. represent % by atomic weight; M is at least one magnetic
metal selected from the group consisting of Fe, Co, and Ni; X is at
least one selected from the group consisting of Mg, Ca, Sr, Ba, Si,
Ge, Sn, Al, Ga, and transition metals excluding the M), wherein
assuming that a chemical formula when the X forms a nitride with a
lowest nitride generation free energy is XN.sub.m, and a chemical
formula when the X forms an oxide with a lowest oxygen generation
free energy is XO.sub.n, the high-resistant magnetic film has the
following composition range:
[0079] .alpha.+.beta.+.gamma.=100
[0080] 45.ltoreq..alpha..ltoreq.78
[0081] .delta.+.epsilon.=100
[0082]
1<100.times..gamma./.beta./(m.times..delta.+n.times..epsilon.)&l-
t;2.5
[0083] the high-resistant magnetic film contains crystal grains,
and a shortest diameter of each of the crystal grains is 20 nm or
less.
[0084] A magnetic multilayer with high resistivity of the present
invention includes a magnetic layer and an intermediate layer
alternately formed, wherein the magnetic layer includes a
high-resistant magnetic film, the high-resistant magnetic film and
the intermediate layer have compositions represented by
M.sub.1m1X.sub.1n1A.sub.1q1 and M.sub.2m2X.sub.2n2A.sub.2q2,
respectively (where m1, n1, q1, m2, n2, and q2 represent % by
atomic weight; M.sub.1 and M.sub.2 are at least one magnetic metal
selected from the group consisting of Fe, Co, and Ni; X.sub.1 and
X.sub.2 are at least one selected from the group consisting of Mg,
Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and transition metals excluding the
magnetic metal; and A.sub.1 and A.sub.2 represent at least one
selected from the group consisting of O and N), and the
high-resistant magnetic film and the intermediate layer satisfy the
following expressions:
[0085] M.sub.1=M.sub.2, X.sub.1=X.sub.2
[0086] q1<q2
[0087] A method for producing a high-resistant layer of the present
invention, includes the steps of: forming a low-resistant layer
containing 10% by atomic weight or more of at least one element
selected from the group consisting of Mg, Ca, Sr, Ba, Si, Ge, Sn,
Al, Ga, and transition metals excluding the M.sub.1 on either one
of a magnetic thin film and a magnetic layer; and oxidizing or
nitriding the low-resistant layer in an atmosphere selected from
the group consisting of oxygen, nitrogen, oxygen plasma, and
nitrogen plasma.
[0088] In one embodiment of the present invention, the magnetic
thin film or the magnetic layer contains an element compatible with
oxygen.
[0089] A magnetic multilayer of the present invention includes a
magnetic thin film and a high-resistant layer alternately formed,
wherein assuming that an average thickness of the magnetic thin
film is T.sub.3, and an average thickness of the high-resistant
layer is T.sub.4, the following expressions are satisfied:
[0090] 100 nm.ltoreq.T.sub.3.ltoreq.1000 nm
[0091] 2 nm.ltoreq.T.sub.4.ltoreq.50 nm
[0092] 10.ltoreq.T.sub.3/T.sub.4.ltoreq.500
[0093] In one embodiment of the present invention, the magnetic
thin film includes a magnetic layer and an intermediate layer, the
magnetic layer, the intermediate layer, and the high-resistant
layer have compositions represented by M.sub.1X.sub.1A.sub.1,
M.sub.2X.sub.2A.sub.2, and M.sub.3X.sub.3A.sub.3, respectively
(where M.sub.1 to M.sub.3 are at least one magnetic metal selected
from the group consisting of Fe, Co, and Ni; X.sub.1, X.sub.2, and
X.sub.3 are at least one selected from the group consisting of Mg,
Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and transition metals excluding the
magnetic metal; and A.sub.1, A.sub.2, and A.sub.3 are at least one
selected from the group consisting of O and N), and the magnetic
layer, the intermediate layer, and the high-resistant layer at
least satisfy the conditions: M.sub.1=M.sub.2=M.sub.3, and
X.sub.1=X.sub.2=X.sub.3.
[0094] A thin film head of the present invention includes an upper
magnetic pole and a lower magnetic pole, wherein the upper magnetic
pole includes either one of a high-resistant magnetic film and a
magnetic multilayer with high resistivity, having a specific
resistance of 80 .mu..OMEGA.cm or more, and either one of a
magnetic thin film and a magnetic multilayer, the upper magnetic
pole and the lower magnetic pole form a recording gap, and either
one of the magnetic thin film and the magnetic multilayer is formed
at least in the vicinity of the recording gap at an end of the
upper magnetic pole.
[0095] In one embodiment of the present invention, either one of
the magnetic thin film and the magnetic multilayer is formed at
least in the recording gap, and either one of the high-resistant
magnetic film and the magnetic multilayer with high resistivity,
having a specific resistance of 80 .mu..OMEGA.cm or more is formed
on either one of the magnetic thin film and the magnetic
multilayer.
[0096] A method for producing a thin film of the present invention,
includes: a first step of moving a substrate onto which a film is
formed and a source for supplying material for forming a film in a
relative manner; and a second step of forming at least one of a
magnetic thin film, a magnetic multilayer, a high-resistant
magnetic film, and a magnetic multilayer with high resistivity,
wherein at least one magnetization difficult axis of the magnetic
thin film, the magnetic multilayer, the high-resistant magnetic
film, and the magnetic multilayer with high resistivity is formed
in a movement direction in which the substrate and the source are
moved in a relative manner.
[0097] In one embodiment of the present invention, the movement
direction includes a depth direction of an upper magnetic pole of a
thin film head.
[0098] In another embodiment of the present invention, the first
step includes forming a film by a vapor growth method for
generating a magnetic field of 50 Oe or more which is substantially
orthogonal to the movement direction, substantially parallel to a
film formation surface on the substrate, substantially uniform, and
substantially in one direction.
[0099] In another embodiment of the present invention, the first
step includes forming a film by changing a concentration of oxygen,
oxygen plasma, nitrogen, or nitrogen plasma in a vapor growth
apparatus.
[0100] In another embodiment of the present invention, a
temperature of the substrate during formation of a film is
substantially 300.degree. C. or less.
[0101] A hard disk drive using the above-mentioned magnetic film as
a magnetic pole.
[0102] A hard disk drive using the above-mentioned magnetic film as
a part of a shield.
[0103] A hard disk drive using the above-mentioned high-resistant
magnetic film as a magnetic pole.
[0104] A hard disk drive using the above-mentioned high-resistant
magnetic film as a part of a shield.
[0105] A hard disk drive using the above-mentioned magnetic
multilayer with high resistivity as a magnetic pole.
[0106] A hard disk drive using the above-mentioned magnetic
multilayer with high resistivity as a part of a shield.
[0107] A hard disk drive using the above-mentioned magnetic
multilayer as a magnetic pole.
[0108] A hard disk drive using the above-mentioned magnetic
multilayer as a part of a shield.
[0109] A hard disk drive using the above-mentioned thin film
head.
[0110] According to an aspect of the present invention, a magnetic
film having outstanding soft magnetic characteristics at a high
frequency and high Bs can be obtained for the following reason.
Magnetic layers are magnetically separated by an intermediate
layer, whereby the magnetic layers disposed via the intermediate
layer decrease domain wall energy due to their magnetostatic
binding or the intermediate layer suppresses the growth of magnetic
crystal grains so as to refine them. Thus, apparent crystal
magnetic anisotropy is decreased (so-called refining effect), which
enhances soft magnetic characteristics.
[0111] Furthermore, even in the case where the thickness and width
of a film have a high aspect ratio during refining of the film,
shape anisotropy magnetic energy in a direction perpendicular to
the film is suppressed, so that outstanding high-frequency
characteristics can be exhibited. Particularly, in the case where a
magnetic film of magnetostatic binding type is used in the vicinity
of a recording gap of an upper magnetic pole of a thin film head,
the magnetization of magnetic layers separated by an intermediate
layer causes magnetostatic binding on the side face of the magnetic
pole, and is likely to be directed in a preferable magnetization
direction similarly to the case where apparent uniaxial anisotropy
is formed; therefore, high-frequency characteristics are enhanced
without conducting heat treatment in a magnetic field or forming a
film in a magnetic field.
[0112] M.sub.1 may be any of Fe, a FeCo alloy, and a FeCoNi alloy.
X.sub.1 contained in a magnetic layer has at least one effect such
as enhancing corrosion resistance, refining crystal grains of
magnetic metal, decreasing crystal magnetic anisotropy of magnetic
crystal grains, and decreasing magnetostriction, as long as its
amount is at least about 0.1%. Zn, Pt, Rh, Ru, and the like enhance
corrosion resistance, Cr, Ge, Ga, V, Al, Si, Ti, and Mo decrease
crystal magnetic anisotropy, and Ti, Si, and Sn decrease
magnetostriction, for example, in the case where M.sub.1 is Fe.
Although one kind of M.sub.1 has an effect, two or more kinds of
M.sub.1 will have more remarkable effect of decreasing a crystal
grain diameter. Furthermore, the addition of Al further decreases a
crystal grain diameter, which has an effect of enhancing soft
magnetic characteristics. If .beta..sub.1 is more than about 12%,
and .delta..sub.1 is more than about 10%, Bs is decreased, which is
not preferable.
[0113] An intermediate layer contains transition metal. Therefore,
even when RIE involving generation of carbonyl of transition metal
is used, a fine pattern can be relatively easily formed. In terms
of processability, it is preferable that transition metal such as
Cr and Pt is used for an intermediate layer. In terms of
suppressing an eddy current loss between layers, a high-resistant
oxide such as SiO.sub.2Al.sub.2O.sub.3 is preferably used. The
intermediate layer of the present invention uses an oxide, a
nitride, or material consisting of an oxide and a nitride having
relatively small energy of dissociation, so that the intermediate
layer allows a high resistance to such a degree as to realize
relatively satisfactory processability and sufficiently suppress an
eddy current.
[0114] Furthermore, X.sub.2 contained in the intermediate layer
forms a reactive product with A.sub.2 to promote separation from
the magnetic layer. X.sub.2 also has an outstanding effect on
magnetostatic binding and refining crystal grains, even in the case
where the intermediate layer of the present invention has a
composition or a thickness which does not suppress an eddy current.
X.sub.2 exhibits its effect in an amount of about 0.1% or more.
When the amount is more than about 80%, processability for
patterning to a fine shape becomes poor or magnetic degradation is
caused due to internal stress or strain.
[0115] It is required that .delta..sub.2 contains an O or N
concentration higher than that of .delta..sub.1. When the
.delta..sub.2 concentration exceeds about 67%, excess oxygen or
nitrogen gas is discharged from the intermediate layer in the
course of heat treatment at a temperature higher than a film
formation temperature, which may damage a film. Thus, the
.delta..sub.2 concentration is about 67% or less.
[0116] In the magnetic thin film with the above-mentioned structure
where M.sub.1=M.sub.2 and X.sub.1=X.sub.2, by using an intermediate
layer having the same element as that of the magnetic layer,
interface energy occurring between the intermediate layer and the
magnetic layer is suppressed. Therefore, magnetoelastic energy
caused by internal stress generated on the interface and anisotropy
energy in the film can be decreased. As a result, a magnetic film
having outstanding soft magnetic characteristics and high Bs can be
obtained. Furthermore, in the case where the intermediate layer of
the magnetic thin film with the structure of the present invention
has a thickness sufficient for realizing magnetostatic binding,
vertical magnetization generated by interface strain can be
suppressed; therefore, a domain structure is realized in which
magnetostatic binding works more effectively.
[0117] Furthermore, interface energy is relatively low. Therefore,
it is not required to form a film at a high temperature for the
purpose of removing strain energy during film formation or after
film formation, or to conduct heat treatment for removing strain at
a high temperature. This allows soft magnetic characteristics to be
easily obtained by a process at a low temperature (about
300.degree. C. or less). Furthermore, in the case where layers of
different materials are formed, when materials with low interface
energy are combined, inter-layer peeling is likely to be caused.
However, according to the present invention, the element common to
the magnetic layer and the intermediate layer functions as glue, so
that the layered film of the present invention has high strength.
Furthermore, since M.sub.1=M.sub.2 and X.sub.1=X.sub.2 are
satisfied, in the case where a vapor deposition, for example, is
used, one source for supplying film formation material suffices to
easily form a film. In the case of the structure of the present
invention, even when the composition of each magnetic layer and
intermediate layer is continuously varied, the same effect can be
obtained.
[0118] According to another aspect of the present invention,
X.sub.2 contained in the intermediate layer is capable of easily
generating a reaction product with A.sub.2, due to its low oxide
generation free energy. Thus, even when the intermediate layer is
relatively thin, it has appropriate separation effect between the
magnetic layers.
[0119] According to still another aspect of the present invention,
at least one selected from the group consisting of Rh, Ru, and Pt
is added to the magnetic layer and the intermediate layer,
respectively, whereby corrosion resistance of thin film material is
remarkably enhanced. The content of these elements of about 0.1% or
more is effective, whereas the content of about 8% or more will
decrease a saturated magnetic flux density, and degrade soft
magnetic characteristics.
[0120] Furthermore, in the magnetic thin film with the
above-mentioned structure in which X.sub.1 is at least one selected
from the group consisting of Si, Al, Ti, and V, in the case where a
trace amount of Si, Al, Ti, and V is contained in crystal grains
included in the magnetic layer, crystal magnetic anisotropy energy
is decreased. This results in a refining effect and a decrease in
domain wall energy. Thus, more outstanding soft magnetic
characteristics can be obtained. When these elements react with O
or N in the magnetic layer, the growth of crystal grains is
suppressed, and a refining effect is enhanced. In the case where
these elements are contained in the intermediate layer, since any
of these elements has large free energy for generating an oxygen or
a nitrogen and has a large diffusion constant, the intermediate
layer can be effective with a relatively small thickness. Such a
relatively thin intermediate layer allows the magnetostatic binding
between the magnetic layers to strengthen; therefore, a decrease in
domain wall energy is large, and a decrease in a saturated magnetic
flux density in the entire film caused by the intermediate layer is
small.
[0121] In the magnetic thin film with the above-mentioned structure
in which A.sub.2 contained in the intermediate layer is O, the
intermediate layer has particularly high thermal stability.
Therefore, for example, even in the case where a heat treatment
temperature in a magnetic field required for fixing an
antiferromagnetic film of a spin valve film in an operation
environment of an HDD is relatively high, soft magnetic
characteristics will not degrade.
[0122] According to still another aspect of the present invention,
outstanding soft magnetic characteristics and high Bs can be
obtained. This may be because soft magnetic characteristics are
exhibited by a kind of refining effect of magnetic crystal
grains.
[0123] The magnetic layer is composed of crystal grains containing
a trace amount of amorphous material, and adjacent magnetic layers
are not required to be completely separated by the intermediate
layer. Even when crystal grains in the magnetic layers interposing
the intermediate layer therebetween are observed to be partially
continued crystallographycally, magnetic strength of crystal grains
of in-plane portions of the film is different from that in a
direction perpendicular to the film passing through the
intermediate layer.
[0124] Therefore, even when the magnetic thin film is refined, for
example, as a magnetic pole of a thin film head, outstanding soft
magnetic characteristics can be exhibited at a high frequency
without being influenced by shape anisotropy in a direction
perpendicular to the film. Soft magnetic characteristics become
particularly outstanding, when the intermediate layer is composed
of amorphous material or microcrystal containing amorphous
material. When the thickness of the magnetic layer is about 2 nm or
less, magnetic characteristics degrade. When the thickness of the
magnetic layer is about 20 nm or more, grains are likely to
excessively grow. Furthermore, unless the thickness of the
intermediate layer is about 0.4 nm or more, crystal grains cannot
be effectively refined. Unless the thickness of the intermediate
layer is about 2 nm or less, soft magnetic characteristics degrade.
This may be because exchange binding between the magnetic layers is
weakened. Furthermore, in terms of Bs, the ratio of film thickness
is preferably 1.ltoreq.T.sub.1/T.sub.2.ltoreq.50.
[0125] According to still another aspect of the present invention,
high Bs as well as outstanding soft magnetic characteristics at a
high frequency can be obtained. This may be because of a kind of
magnetostatic binding effect. The magnetic layer is composed of
crystal grains or crystal grains containing a trace amount of
amorphous material.
[0126] The magnetic layers are not required to be electrically
insulated by the intermediate layer. When the thickness of the
magnetic layer is about 20 nm or less, or larger than about 150 nm,
magnetostatic binding becomes less effective. When the thickness of
the intermediate layer is about 2 nm or less, the magnetic layers
cannot be sufficiently separated, and exchange binding therebetween
becomes strong. When the thickness of the intermediate layer
exceeds about 15 nm, the distance between the magnetic layers
becomes large, which results in that sufficient magnetostatic
binding is unlikely to occur. If the shortest diameter of crystal
grains included in the magnetic layer is about 20 nm or less which
is sufficient for allowing a refining effect, in addition to
magnetostatic binding, soft magnetic characteristics are further
enhanced. The above-mentioned preferable thickness is considered to
be determined in such a manner that the total of magnetostatic
energy (which decreases due to magnetostatic binding of the
magnetic thin film in a composition range of the present invention)
and various energies (which are related to a domain structure
resulting from a multi-layer structure). In terms of Bs, the ratio
of film thickness is preferably
4.ltoreq.T.sub.1/T.sub.2.ltoreq.50.
[0127] According to still another aspect of the present invention,
a high-resistant layer has an effect of suppressing an eddy
current, and compositions of the magnetic layer, the intermediate
layer, and the high-resistant layer are close to each other.
Therefore, interface energy occurring on an interface between
different kinds of layers can be suppressed. This will decrease
magnetostriction multiplied by strain energy, caused by an internal
stress occurring on the interface, and anisotropic energy in the
film.
[0128] Consequently, a magnetic film having outstanding soft
magnetic characteristics and high Bs can be obtained even in the
case where the total thickness is relatively large. Furthermore,
interface energy is relatively low. Therefore, it is not required
to form a film at a high temperature for the purpose of removing
strain energy during film formation or after film formation, or to
conduct heat treatment for removing strain at a high temperature.
This allows soft magnetic characteristics to be easily obtained by
a process at a low temperature (about 300.degree. C. or less).
[0129] Furthermore, in the case of using vapor deposition,
depending upon the composition of the magnetic film of the present
invention, one source for supplying a film formation material
suffices. Therefore, high-speed film formation can be conducted
with a simple apparatus and satisfactory mass-productivity.
Furthermore, in the case where layers of different materials are
formed, when materials with low interface energy are combined,
inter-layer peeling is likely to be caused. However, according to
the present invention, the element common to the magnetic layer and
the intermediate layer functions as glue, so that the layered film
of the present invention has high strength.
[0130] According to the present invention, a high-resistant layer
of a magnetic multilayer with the above-mentioned structure is
produced by forming a low-resistant layer containing at least one
selected from the group consisting of Mg, Ca, Sr, Ba, Si, Al, Ti,
and Cr in an amount of about 10% by atomic weight or more on a
magnetic thin film or a magnetic layer, and oxidizing or nitriding
the low-resistant layer in an atmosphere of oxygen/oxygen plasma or
nitrogen/nitrogen plasma. Thus, a high-resistant layer with a
relatively small thickness and outstanding insulation can be
produced. The low-resistant layer may be formed of either of Si,
Al, Ti, and Cr, or may be formed of an alloy film thereof. Even
when the low-resistant layer is formed of an alloy with magnetic
transition metal such as Fe, an excellent high-resistant layer can
be produced, as long as at least one of Mg, Ca, Sr, Ba, Si, Al, Ti,
and Cr is contained in an amount of about 10% by atomic weight or
more. A relatively thin insulation layer has outstanding
magnetostatic binding characteristics, so that both high soft
magnetic characteristics and outstanding high frequency
characteristics can be obtained.
[0131] Furthermore, in a thin film head having a structure in which
at least an upper magnetic pole is composed of a high-resistant
magnetic film or a magnetic multilayer with high resistivity,
having a specific resistance of about 80 .mu..OMEGA.cm or more and
a magnetic thin film or a magnetic multilayer with the
above-mentioned structure, and the magnetic thin film or the
magnetic multilayer is formed at least in the vicinity of a
recording gap at an end portion of the upper magnetic pole,
outstanding overwrite characteristics are exhibited at a high
frequency even at a relatively low recording current. This is
because of the following: high Bs material of the present invention
is used for the end portion of the recording gap of a recording
head in the upper magnetic pole where a magnetic flux with its core
width narrowed is likely to be saturated, and a high-resistant
magnetic film or a magnetic multilayer with high resistivity having
a small loss of an eddy current is used for another portion of the
upper magnetic pole for inducing a magnetic flux into the end
portion of the recording gap.
[0132] The high-resistant film may be a layered film of a
high-resistant layer and a magnetic layer, or may be a
high-resistant single film in which a grain boundary of
microcrystal grains considered to be granular is substantially
surrounded by high-resistant amorphous material. It is important
that the high-resistant film is a soft magnetic film with a
specific resistance of about 80 .mu..OMEGA.cm or more. When the
present invention is applied to a lower magnetic pole as well as
the upper magnetic pole, a recording current can be further
decreased.
[0133] Furthermore, a thin film head with the above-mentioned
structure, in which a magnetic thin film or a magnetic multilayer
with the above-mentioned structure is formed at least on a
recording gap, and a high-resistant magnetic film or a magnetic
multilayer with high resistivity having a specific resistance of
about 80 .mu..OMEGA.cm or more is formed on the magnetic thin film
or the magnetic multilayer, exhibits outstanding overwrite
characteristics at a relatively low recording current. Such a thin
film head can be produced by a simple process. The high-resistant
film herein should also be a soft magnetic film with a specific
resistance of about 80 .mu..OMEGA.cm or more.
[0134] According to still another aspect of the present invention,
a thin film head having outstanding high-frequency characteristics
can be produced. This is because of the following: high-resistant
material having the composition and structure of the present
invention can suppress an eddy current loss, so that recording
ability at a high frequency can be remarkably improved. A specific
resistance of about 80 .mu..OMEGA.cm or more is caused by a
high-resistant X--O or N compound formed in a magnetic crystal
grain boundary.
[0135] Furthermore, it is important that O and N should be
contained in a range required for forming an X--O or N compound,
represented by the above-mentioned expression. Soft magnetic
characteristics are caused by microcrystal grains having the
shortest diameter of about 20 nm or less. The microcrystal grains
have a structure close to a needle-shape or a grain-shape.
[0136] According to still another aspect of the present invention,
a thin film head having outstanding high-frequency characteristics
can be produced. The above-mentioned high-resistant thin film
comprises microcrystals having the shortest diameter of about 20 nm
or less or comprises microcrystal and amorphous material.
Therefore, a number of crystal grain boundaries are formed, and as
a result, crystal grains do not move smoothly because of domain
walls, and a domain wall resonance loss is increased.
[0137] However, in a layered structure of the present invention, a
domain wall structure is changed so that magnetostatic energy of
the entire film is decreased; as a result, domain wall energy is
decreased, and a domain wall resonance loss at a high frequency is
decreased. Furthermore, in the case where, due to a leakage
magnetic field from the high-resistant magnetic film, magnetostatic
binding occurs in the high-resistant magnetic film and in the
magnetic thin film or the magnetic multilayer included in the upper
magnetic pole, magnetostatic energy over the entire thin film head
is decreased and high-frequency characteristics are enhanced.
[0138] Furthermore, since the composition of the magnetic layer is
close to that of the intermediate layer, interface energy occurring
on an interface between different kinds of layers can be
suppressed. This will decrease magnetostriction multiplied by
strain energy, caused by an internal stress occurring on the
interface, and anisotropic energy in the film. Furthermore, in the
case of using vapor deposition, depending upon the composition of
the high-resistant magnetic film of the present invention, one
source for supplying a film formation material suffices. Therefore,
high-speed film formation can be conducted with a simple apparatus
and satisfactory mass-productivity.
[0139] Furthermore, according to the present invention, a magnetic
thin film (or magnetic multilayer) and a high-resistant magnetic
film (or magnetic multilayer with high resistivity) are formed by
vapor deposition while a positional relationship between a
substrate and a source for supplying film formation material is
changed during film formation, and a magnetization difficult axis
of a thin film is formed in the direction of relative movement
between the substrate and the source. In this method, uniaxial
magnetic anisotropy formed in the thin film is determined mainly by
a growth direction of magnetic crystal grains included in the
magnetic film and the diameter of a fine crystal grain. Therefore,
for example, even in the case where a heat treatment for fixing an
antiferromagnetic film of a spin valve film in an operation
environment of an HDD is conducted while a magnetic field is
applied in a direction orthogonal to a direction of a magnetization
easy axis of the magnetic thin film (or the magnetic multilayer)
and the high-resistant magnetic film (or the magnetic multilayer
with high resistivity), anisotropy is unlikely to be disturbed.
[0140] According to a method for producing a thin film for a thin
film head in which a direction of relative movement is in a depth
direction of an upper magnetic pole of the thin film head, a
magnetization difficult axis which is stable against heat treatment
is formed in the depth direction of the upper magnetic pole, and
the film quality on a slope surface of the upper magnetic pole is
improved. Therefore, a thin film head having outstanding recording
characteristics can be produced.
[0141] In a magnetic thin film (or magnetic multilayer), a
high-resistant magnetic film (or magnetic multilayer with high
resistivity), and a thin film head with the above-mentioned
structure formed by using a vapor growth method for generating a
magnetic field of about 50 Oe or more which is substantially
orthogonal to the movement direction, substantially parallel to a
film formation surface on the substrate, substantially uniform, and
substantially in one direction, the intensity of uniaxial
anisotropy of the magnetic thin film (or the magnetic multilayer)
and the high-resistant magnetic film (or the magnetic multilayer)
is averaged. Thus, high-frequency characteristics are stabilized
over the entire thin film head.
[0142] According to still another aspect of the present invention,
a magnetic layer and an intermediate layer of a magnetic thin film;
a magnetic layer, an intermediate layer, and a high-resistant layer
of a magnetic multilayer; and a magnetic layer and an intermediate
layer of a high-resistant magnetic film or a magnetic multilayer
with high resistivity can be produced by using the same source for
supplying film formation material. Therefore, a vapor growth
apparatus can be miniaturized, and films can be formed at a high
speed.
[0143] Furthermore, according to a method for producing a magnetic
thin film, a magnetic multilayer, a high-resistant magnetic film, a
magnetic multilayer with high resistivity, and a thin film head
with the above-mentioned structure in which a substrate temperature
is substantially about 300.degree. C. or less, even a very thin
intermediate layer (which cannot be used at a high temperature of
about 500.degree. C.) can be used. Because of a relatively low
production temperature (about 300.degree. C. or less), such a very
thin intermediate layer does not have its structure changed due to
heat diffusion. The very thin intermediate layer allows the
strongest magnetostatic binding between magnetic layers disposed
via the intermediate layer, as long as the magnetic thin film is of
a magnetostatic binding type with the above-mentioned structure.
Also, a very thin high-resistant layer which does not allow Bs to
decrease can easily be formed. With a high Bs composition (i.e.,
with a composition in which a metal magnetic element ratio is
large), crystal grains are likely to grow by heat treatment.
However, since a production temperature is relatively low, crystal
grains can easily be maintained in a fine state, and a magnetic
thin film or a magnetic multilayer using the above-mentioned
refining effect can easily be realized. Because of this, high Bs, a
high resistance, and outstanding high frequency characteristics are
realized, and a thin film head with high corrosion resistance
caused by microcrystal and/or amorphous material can be
provided.
[0144] Furthermore, in an HDD using, at least for a magnetic pole
or a part of a shield, a magnetic thin film, a magnetic multilayer,
a high-resistant magnetic film, or a magnetic multilayer with high
resistivity having the above-mentioned structure, and in an
information processing apparatus using such an HDD, a high
recording density can be realized at a frequency of about 100 MHz
or more. Thus, an apparatus can be miniaturized and rendered
light-weight.
[0145] Furthermore, in an HDD using a thin film head with the
above-mentioned structure and in an information processing
apparatus using such an HDD, in addition to miniaturization of an
apparatus and rendering an apparatus light-weight due to a high
recording density, a power consumption can be reduced due to a
decreased recording current. As a result, a battery of a portable
information processing apparatus provided with the HDD can be
miniaturized, and such a portable apparatus can be used
continuously for a longer period of time.
[0146] Thus, the invention described herein makes possible the
advantages of providing a soft magnetic material with high BS
having outstanding high frequency characteristics and a method for
producing the same.
[0147] These and other advantages of the present invention will
become apparent to those skilled in the art upon reading and
understanding the following detailed description with reference to
the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0148] FIG. 1 shows magnetic characteristics of a magnetic film of
Example 1 according to the present invention.
[0149] FIG. 2 shows magnetic characteristics of a magnetic film of
Example 1 according to the present invention.
[0150] FIG. 3 shows magnetic characteristics of a magnetic film of
Example 1 according to the present invention.
[0151] FIG. 4 shows magnetic characteristics of a magnetic film of
Example 1 according to the present invention.
[0152] FIG. 5 shows magnetic characteristics of a magnetic film of
Example 1 according to the present invention.
[0153] FIG. 6 shows magnetic characteristics of a magnetic film of
Example 2 according to the present invention.
[0154] FIG. 7 shows magnetic characteristics of a magnetic film of
Example 2 according to the present invention.
[0155] FIG. 8 shows magnetic characteristics of a magnetic film of
Example 3 according to the present invention.
[0156] FIG. 9 shows magnetic characteristics of a magnetic film of
Example 3 according to the present invention.
[0157] FIG. 10 shows magnetic characteristics of a magnetic film of
Example 4 according to the present invention.
[0158] FIG. 11 shows magnetic characteristics of a magnetic film of
Example 4 according to the present invention.
[0159] FIG. 12 shows magnetic characteristics of a magnetic film of
Example 4 according to the present invention.
[0160] FIG. 13 shows magnetic characteristics of a magnetic film of
Example 4 according to the present invention.
[0161] FIG. 14 shows magnetic characteristics of a magnetic film of
Example 4 according to the present invention.
[0162] FIG. 15 shows magnetic characteristics of a magnetic film of
Example 4 according to the present invention.
[0163] FIG. 16 shows magnetic characteristics of a magnetic film of
Example 5 according to the present invention.
[0164] FIG. 17 shows magnetic characteristics of a magnetic film of
Example 5 according to the present invention.
[0165] FIG. 18A illustrates a method for producing a high-resistant
layer of Example 5 according to the present invention.
[0166] FIG. 18B illustrates a method for producing a high-resistant
layer of Example 5 according to the present invention.
[0167] FIG. 18C illustrates a method for producing a high-resistant
layer of Example 5 according to the present invention.
[0168] FIG. 18D illustrates a method for producing a high-resistant
layer of Example 5 according to the present invention.
[0169] FIG. 18E is a flow chart of a method for producing a
high-resistant layer of Example 5 according to the present
invention.
[0170] FIG. 19A illustrates another method for producing a
high-resistant layer of Example 5 according to the present
invention.
[0171] FIG. 19B illustrates still another method for producing a
high-resistant layer of Example 5 according to the present
invention.
[0172] FIG. 19C illustrates still another method for producing a
high-resistant layer of Example 5 according to the present
invention.
[0173] FIG. 20 shows magnetic characteristics of a high-resistant
magnetic film of Example 6 according to the present invention.
[0174] FIG. 21 shows magnetic characteristics of a high-resistant
magnetic film of Example 6 according to the present invention.
[0175] FIG. 22 is a cross-sectional view of a conventional thin
film head.
[0176] FIG. 23 is a schematic cross-sectional view of a thin film
head using a magnetic film of Example 7 according to the present
invention.
[0177] FIG. 24 is a schematic cross-sectional view of a thin film
head using a magnetic multilayer with high resistivity of Example 7
according to the present invention.
[0178] FIG. 25 is a schematic cross-sectional view of a thin film
head using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0179] FIG. 26 is a schematic cross-sectional view of a thin film
head using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0180] FIG. 27 is a schematic cross-sectional view of a thin film
head using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0181] FIG. 28 is a schematic cross-sectional view of a thin film
head using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0182] FIG. 29 is a schematic cross-sectional view of a thin film
head using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0183] FIG. 30 is a schematic cross-sectional view of a thin film
head using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0184] FIG. 31 shows a structure of a magnetron sputtering device
used in the method for producing a thin film of example 7 according
to the present invention.
[0185] FIG. 32A illustrates a method for producing a thin film head
using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0186] FIG. 32B illustrates a method for producing a thin film head
using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0187] FIG. 32C illustrates a method for producing a thin film head
using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0188] FIG. 33A illustrates another method for producing a thin
film head using a magnetic film and a magnetic multilayer with high
resistivity of Example 7 according to the present invention.
[0189] FIG. 33B illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0190] FIG. 33C illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0191] FIG. 34 shows overwrite characteristics of a thin film head
of Example 7 according to the present invention.
[0192] FIG. 35A illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0193] FIG. 35B illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0194] FIG. 35C illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0195] FIG. 36A illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0196] FIG. 36B illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0197] FIG. 36C illustrates still another method for producing a
thin film head using a magnetic film and a magnetic multilayer with
high resistivity of Example 7 according to the present
invention.
[0198] FIG. 36D is a flow chart of still another method for
producing a thin film head using a magnetic film and a magnetic
multilayer with high resistivity of Example 7 according to the
present invention.
[0199] FIG. 37 shows magnetic characteristics of a thin film head
of Example 8 according to the present invention.
[0200] FIG. 38 is a side view of a hard disk apparatus of the
present invention.
[0201] FIG. 39 is a plan view of the hard disk apparatus of the
present invention.
[0202] FIG. 40 is a view illustrating a conventional thin film
magnetic layer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0203] A magnetic film having the structure and composition
according to the present invention is most preferably formed by
vapor deposition under a low gas pressure. There is no particularly
preferential procedure for vapor deposition. However, for example,
a magnetic film can be formed by sputtering such as RF magnetron
sputtering, DC sputtering, opposed target sputtering, and ion beam
sputtering, or reactive vapor deposition in which reactive gas is
introduced into the vicinity of a substrate, and material for vapor
deposition is dissolved. The present invention is practiced by
sputtering as follows. A magnetic film, a magnetic multilayer, or a
high-resistant magnetic film is formed on a substrate by subjecting
an alloy target to sputtering in an atmosphere of an inactive gas.
In this case, the alloy target is determined for its composition,
considering the compositions of a magnetic layer and an
intermediate layer included in the magnetic film, a magnetic layer,
an intermediate layer and a high-resistant layer included in the
magnetic multilayer, or a high-resistant magnetic film after being
formed. Alternatively, a pellet for adding elements is placed over
a metal target; under this condition, the metal target is subject
to sputtering. Alternatively, a part of an additive in a gas state
is doped in an apparatus (reactive sputtering). Thus, each layer
should be successively formed to a required thickness. An electrode
for discharging may be at least one depending upon the
composition.
[0204] Herein, by controlling a discharge gas pressure, a discharge
power, a substrate temperature, a bias state of a substrate, a
magnetic field on a target and in the vicinity of a substrate, a
target shape, a direction in which particles are incident upon a
substrate, and the kind of discharge gas, a structure of a magnetic
film, a thermal expansion coefficient, film characteristics
obtained by a relative position between a substrate and a target,
etc. can be regulated.
EXAMPLES
[0205] In the following examples, a magnetic film is produced by RF
magnetron sputtering or DC magnetron sputtering. A substrate
temperature is in a range of room temperature to about 100.degree.
C. This is because of the natural increase in temperature caused by
energy during formation of films. Practically, it is possible to
produce a preferable magnetic film as long as a substrate
temperature is about 250.degree. C. or less. A film structure is
observed by X-ray diffraction (XRD) or a transmission electron
microscope (TEM). A composition is analyzed by electron probe micro
analysis (EPMA), and a coercivity and a saturated magnetic flux
density are evaluated by a BH loop tracer and a vibration sample
magnetometer (VSM), respectively. The composition of each layer
such as an intermediate layer and a magnetic layer in the examples
is indicated in terms of that of a single layer (about 3 .mu.m)
obtained under the condition of producing each layer.
[0206] Hereinafter, the present invention will be described by way
of illustrative examples.
Example 1
[0207] The present example shows the results obtained by examining
thicknesses of a magnetic layer (FeSi) and an intermediate layer
(FeSiO) included in a magnetic film.
[0208] The experimental conditions are as follows:
[0209] Substrate: non-magnetic ceramic substrate
[0210] Substrate temperature: room temperature to about 100.degree.
C.
[0211] Target of a magnetic film: FeSi alloy target
[0212] Target size: about 3 inches
[0213] Discharge gas pressure: about 8 mTorr
[0214] Discharge electric power: about 300 W
[0215] Sputtering gas: Ar for a magnetic layer
[0216] Ar+O.sub.2 for an intermediate layer (where an oxygen flow
ratio O.sub.2/(Ar+O.sub.2) is about 3% or about 25%)
[0217] The composition of a single layer obtained by using Ar alone
in the present example is about Fe.sub.94.0Si.sub.6.0.
[0218] As shown in FIG. 1, it is preferable that Bs is about 1.5 T
or more, and a coercivity is about 2.0 Oe or less. Depending upon
the use, Bs may be less than about 1.5 T, or a coercivity may be
larger than about 2.0 Oe.
[0219] FIGS. 1 through 4 show magnetic characteristics of
FeSi/FeSiO magnetic films each obtained by using a FeSi alloy
target in an atmosphere of Ar gas for a magnetic layer and
Ar+O.sub.2 (oxygen flow ratio is about 25%) for an intermediate
layer, with varying thickness of the magnetic layer or the
intermediate layer.
[0220] FIG. 5 shows the results obtained by changing the thickness
of a magnetic layer in each FeSi/FeSiO magnetic film produced in an
atmosphere of Ar+O.sub.2 gas (oxygen flow ratio is about 3%) for an
intermediate layer.
[0221] The cross-sections of films of Comparative Example ab and
Example aa shown in FIG. 1 are observed with a TEM. In Comparative
Example ab in which the intermediate layer is relatively thin, more
than 50% magnetic crystal grains in a magnetic layer spread to an
adjacent magnetic layer across an intermediate layer. In Example ba
shown in FIG. 2 in which soft magnetic characteristics are
satisfactory while the intermediate layer is relatively thin, many
crystal grains in a magnetic layer spread to an adjacent magnetic
layer across an intermediate layer. However, due to the small
thickness ratio of the intermediate layer and the magnetic layer,
soft magnetic characteristics over the entire film are more
satisfactory than those in Comparative Example ab. As is understood
from this, in a magnetic film including a relatively thick magnetic
layer, it is important that at least 50% crystal grains spread
across the intermediate layer, in addition to the small thickness
ratio of the intermediate layer and the magnetic layer.
[0222] Any of the magnetic layers shown in FIGS. 1 to 4 contain
crystal grains of about 10 nm or more, whereas any of the
intermediate layers is amorphous or contains crystal grains of
several nm.
[0223] In the present example, the magnetic film is subjected to
pre-sputtering sufficiently during production of the magnetic layer
and the intermediate layer. In addition to this, while the magnetic
layer is formed by RF sputtering in an atmosphere of Ar gas, the
intermediate layer is formed by intermittently introducing oxygen
gas, whereby the magnetic layer and the intermediate layer are
alternately formed continuously to obtain a magnetic thin film. It
this case, it is found that about 1% to about 2% oxygen gas is
added to the magnetic layer. The relationship in thickness between
the intermediate layer and the magnetic layer in the magnetic thin
film thus continuously produced is examined, which reveals that
preferable soft magnetic characteristics can be obtained at the
same thicknesses as those of the magnetic layer and the
intermediate layer in the present example.
[0224] In the present example, FeSi and FeSiO are used for the
magnetic layer and the intermediate layer, respectively. However,
in the case where Fe contained in the magnetic layer or the
intermediate layer is replaced by FeCo or FeCoNi, in the case where
Si is replaced by at least one selected from the group consisting
of Ge, Sn, Al, Ga, and transition metals (in particular, IVa group
element, Va group element, or Cr), in the case where an appropriate
amount or less of oxygen or nitrogen is added to the magnetic
layer, or in the case where oxygen or nitrogen is appropriately
added to the intermediate layer in an amount more than that in the
magnetic layer, outstanding soft magnetic characteristics are
obtained immediately after formation of the film to the completion
of heat treatment (about 300.degree. C.), with the same thicknesses
of the magnetic layer and the intermediate layer as those in the
present example.
[0225] In particular, regarding samples in which Si is replaced by
Al, Ti, or V, high Bs as well as satisfactory soft magnetic
characteristics are obtained. Furthermore, in the case where about
8% by atomic weight or less of Pt, Rh, or Ru is contained in
elements excluding oxygen or nitrogen in the samples, corrosion
resistance is enhanced.
[0226] The following is understood from the above-mentioned
results.
[0227] Assuming that the average thickness of the magnetic layer is
T.sub.1 and the average thickness of the intermediate layer is
T.sub.2, the magnetic films satisfying the expressions below can
have outstanding soft magnetic characteristics and high Bs.
[0228] 2 nm.ltoreq.T.sub.1.ltoreq.150 nm
[0229] 0.4 nm.ltoreq.T.sub.2.ltoreq.15 nm
[0230] 1.ltoreq.T.sub.1/T.sub.2.ltoreq.150
[0231] In particular, among these magnetic films, those which
satisfy the expressions below and in which at least 50% magnetic
crystal grains in the magnetic layers disposed via the intermediate
layer spread across the intermediate layer have outstanding
high-frequency characteristics and allow magnetostatic binding to
effectively occur.
[0232] 20 nm.ltoreq.T.sub.1.ltoreq.150 nm
[0233] 1 nm.ltoreq.T.sub.2.ltoreq.15 nm
[0234] 4.ltoreq.T.sub.1/T.sub.2.ltoreq.50
Example 2
[0235] The present example shows the results obtained by examining
the added amounts of Si, O, and N in a magnetic layer of a magnetic
film. The magnetic film of the present example includes a magnetic
layer (FeSi(O)(N)) and an intermediate layer (FeSiO).
[0236] The experimental conditions are as follows:
[0237] Substrate: non-magnetic ceramic substrate
[0238] Substrate temperature: room temperature to about 100.degree.
C.
[0239] Target of a magnetic film: Fe or FeSi alloy target
[0240] Target size: about 3 inches
[0241] Discharge gas pressure: about 8 mTorr
[0242] Discharge electric power: about 300 W
[0243] Sputtering gas: Ar+(O.sub.2)+(N.sub.2) for a magnetic
layer
[0244] Ar+O.sub.2+(N.sub.2) for an intermediate layer
[0245] As shown in FIG. 6, it is preferable that Bs is about 1.5 T
or more, and a coercivity is about 2.5 Oe or less. Depending upon
the use, Bs may be less than 1.5 T, or a coercivity may be larger
than about 2.5 Oe.
[0246] FIG. 6 shows magnetic characteristics of Fe/FeO or
FeSi/FeSiO magnetic films each obtained by using a Fe or FeSi alloy
target. Herein, the magnetic layer is obtained by sputtering in an
atmosphere of Ar gas and the intermediate layer is obtained by
sputtering, using the same target as that in the magnetic layer, in
an atmosphere of Ar+O.sub.2 gas (oxygen flow ratio is about 25%).
The thicknesses of the FeSi magnetic layer and the FeSiO
intermediate layer are fixed to about 70 nm and about 5 nm,
respectively.
[0247] FIG. 7 shows the results of FeSi(O)(N)/FeSiO magnetic films
produced by varying the added amounts of oxygen and nitrogen in the
magnetic layer. Herein, the magnetic layer is obtained by
sputtering in an atmosphere of Ar+(O.sub.2)+(N.sub.2) gas and the
intermediate layer is obtained by sputtering, using the same target
as that in the magnetic layer, in an atmosphere of
Ar+O.sub.2+(N.sub.2) gas (oxygen flow ratio is about 25%). The
thicknesses of the FeSi magnetic layer and the FeSiO intermediate
layer are fixed to about 100 nm and about 7 nm, respectively.
[0248] The above-mentioned values are all immediately after
formation of the films. Any of the magnetic films of the present
example show satisfactory soft magnetic characteristics even after
heat treatment at about 300.degree. C. It is understood from
Comparative Example fa and Example fa shown in FIG. 6 that the
addition of at least about 0.1% by atomic weight of Si will
substantially enhance soft magnetic characteristics. Furthermore,
it is understood from Examples and Comparative Examples shown in
FIG. 7 that in the case where the added amount of Si is relatively
small, the content of oxygen or nitrogen is preferably about 10% by
atomic weight or less.
[0249] In the present example, FeSi(O)(N) and FeSiO are used for
the magnetic layer and the intermediate layer, respectively.
However, in the case where Fe in the magnetic layer or the
intermediate layer is replaced by FeCo and FeCoNi, or in the case
where Si is replaced by at least one of Ge, Sn, Al, Ga, and
transition metals (in particular, IVa group element, Va group
element, or Cr), outstanding soft magnetic characteristics are
obtained immediately after formation of the film to the completion
of heat treatment (about 300.degree. C.), as long as the content of
oxygen or nitrogen in the magnetic layer is in a preferable range
of the present example, and the composition of metal or semi-metal
added to magnetic metal is in a preferable range of the present
example.
[0250] In particular, regarding samples in which Si is replaced by
Al, Ti, or V, high Bs as well as satisfactory soft magnetic
characteristics are obtained. Furthermore, in the case where about
8% by atomic weight or less of Pt, Rh, or Ru is contained in
elements excluding oxygen or nitrogen in the samples, corrosion
resistance is enhanced.
[0251] In summary, if the composition of the magnetic layer is
expressed by
(M.sub.1.alpha..sub.1X.sub.1.beta..sub.1).sub.100-.delta..sub.1A.sub.1-
.delta..sub.1 (where .alpha..sub.1, .beta..sub.1, and .delta..sub.1
represent % by atomic weight; M.sub.1 is at least one magnetic
metal selected from the group consisting of Fe, Co, and Ni; X.sub.1
is at least one selected from the group consisting of Si, Ge, Sn,
Al, Ga, and transition metals excluding M.sub.1; A.sub.1 is at
least one selected from the group consisting of O and N), the
composition is in a range represented as follows:
[0252] 0.1.ltoreq..beta..sub.1.ltoreq.12
[0253] .alpha..sub.1+.beta..sub.1=100
[0254] 0.ltoreq..delta..sub.1.ltoreq.10
Example 3
[0255] The present example shows the results obtained by varying
the kind of intermediate layer.
[0256] FIG. 8 shows the compositions of intermediate layers, and
soft magnetic characteristics of magnetic thin film produced by
using the intermediate layers.
[0257] Herein, each magnetic layer is produced by sputtering in an
atmosphere of Ar gas, and each intermediate layer is produced by
sputtering, using the same target as that in the magnetic layer, in
an atmosphere of Ar+(O.sub.2)+(N.sub.2) gas. The composition of a
FeSi magnetic layer is Fe.sub.96.5Si.sub.3.5, and has a thickness
of about 10 nm. The thickness of each intermediate layer is fixed
to about 2 nm.
[0258] The values shown in FIG. 8 are obtained by conducting heat
treatment at about 250.degree. C. in a vacuum. The intermediate
layers containing oxygen or nitrogen have a large Si/Fe ratio. As
is understood by comparing Example ha or hd with Comparative
Example ha, soft magnetic characteristics are enhanced even by the
addition of a trace amount of O or N. In Comparative Example hb,
soft magnetic characteristics are not so unsatisfactory; however,
surface roughness is caused after heat treatment. More
specifically, it is found that the amount of oxygen or nitrogen
contained in an intermediate layer should be more than that in a
magnetic layer and 67% or less.
[0259] FIG. 9 shows the composition of each intermediate layer
produced by using a target different from that in a magnetic layer,
and soft magnetic characteristics of magnetic thin films obtained
by using the intermediate layers. Each magnetic layer is produced
by sputtering in an atmosphere of Ar gas. The composition of FeSi
magnetic layer is Fe.sub.96.5Si.sub.3.5, and has a thickness of
about 100 nm. Each intermediate layer is produced by sputtering in
an atmosphere of Ar+(O.sub.2)+(N.sub.2) gas so as to have each
composition shown in FIG. 9. The thickness of each intermediate
layer is fixed to about 5 nm. FIG. 9 also shows a processing speed
when each intermediate layer is etched by sputtering in an
atmosphere of Ar gas at about 400 W and about 5 mTorr.
[0260] FIG. 9 shows the results obtained by conducting heat
treatment at 250.degree. C. in a vacuum after formation of the
films. As is understood by comparing Examples with Comparative
Examples, when the amount of Ti, Cr, V, Si, or Al with respect to
Fe is increased, soft magnetic characteristics slightly degrade,
and the processing speed of the intermediate layer is largely
decreased. More specifically, when Ti, Cr, V, Si, or Al is added in
an amount more than 4 times that of Fe, soft magnetic
characteristics degrade and a processing speed is decreased.
[0261] In the present example shown in FIGS. 8 and 9, FeSi is used
for the magnetic layer, and FeSi(O) (N) is used for the
intermediate layer. However, even in the case where Fe in the
intermediate layer is replaced by FeCo or FeCoNi, or even in the
case where Si is replaced by at least one selected from the group
consisting of Mg, Ca, Sr, Ba, Ge, Sn, Al, Ga, and transition metals
(in particular, a IVa group, a Va group, or Cr) under the condition
that the magnetic layer is in a preferable composition range as
shown in Example 2, outstanding soft magnetic characteristics are
obtained immediately after formation of a film to the completion of
heat treatment at about 300.degree. C., and an outstanding
processing speed is obtained. In this case, it is required that the
content of oxygen or nitrogen in the intermediate layer is in the
same range as that in the present example, or the added amount of
metal and semi-metal in the intermediate layer is 4 times or less
that of magnetic metal.
[0262] In summary, if the composition of the intermediate layer of
the magnetic thin film of the present invention is expressed by
(M.sub.2.alpha..sub.2X.sub.2.beta..sub.2).sub.100-.delta..sub.2A.sub.2.de-
lta..sub.2 (where .alpha..sub.2, .beta..sub.2, and .delta..sub.2
represent % by atomic weight; M.sub.2 is at least one magnetic
metal selected from the group consisting of Fe, Co, and Ni; X.sub.2
is at least one selected from the group consisting of Si, Ge, Sn,
Al, Ga, and transition metals excluding M.sub.1; A.sub.2 is at
least one selected from the group consisting of O and N), the
composition is in a range represented as follows:
[0263] 0.1.ltoreq..beta..sub.2.ltoreq.80
[0264] .alpha..sub.2+.beta..sub.2=100
[0265] .delta..sub.1.ltoreq..delta..sub.2.ltoreq.67
Example 4
[0266] The present example shows the results obtained by examining
the added elements contained in a magnetic layer.
[0267] The experimental conditions are as follows:
[0268] Substrate: non-magnetic ceramic substrate
[0269] Substrate temperature: room temperature to about 100.degree.
C.
[0270] Target of a magnetic film: complex target in which an
element chip with metal or semi-metal shown in FIGS. 10 to 15 added
thereto is placed on a Fe target. The same target is used for a
magnetic layer and an intermediate layer.
[0271] Discharge gas pressure: about 8 mTorr
1 Discharge electric power: about 300 W Sputtering gas: Ar +
(0.sub.2) + (N.sub.2) for a magnetic layer Oxygen flow ratio
0.sub.2/(Ar + O.sub.2) is about 0% to about 1.5% Nitrogen flow
ratio N.sub.2/(Ar + N.sub.2) is about 0% to about 5% (only magnetic
layers with nitrogen added thereto) Ar + O.sub.2 + (N.sub.2) for an
intermediate layer Oxygen flow ratio O.sub.2/(Ar + O.sub.2) is
fixed to be about 20% Nitrogen flow ratio N.sub.2/(Ar + N.sub.2) is
about 0% to about 5% (only magnetic layers with nitrogen added
thereto)
[0272] Sputtering gases with the above-mentioned flow ratios are
alternately switched during formation of a film.
[0273] FIGS. 10 through 15 show soft magnetic characteristics of
magnetic thin films and compositions of magnetic layers included in
the magnetic thin films. A Fe single layer is listed as Comparative
Example ja. The thickness of each magnetic layer is about 70 nm,
and the thickness of each intermediate layer is about 5 nm. In the
present example, it is confirmed, from Auger depth profile results
obtained by continuously forming a magnetic layer and a
non-magnetic layer while switching reactive gases during sputtering
using the same target, that magnetic elements and added elements
contained in the magnetic layer are added to the intermediate
layer, and oxygen is added to the intermediate layer in an amount
equal to or more than that in the magnetic layer. However, an exact
composition of the intermediate layer is unclear.
[0274] Switching of reactive gases includes switching of power
supplies to a plasma generation source, switching of a mixed ratio
of argon inactive gas, switching of a discharge gas pressure during
sputtering, switching of a sputtering power, and switching of a gas
flow ratio.
[0275] The amount of elements of each magnetic layer shown in FIGS.
10 through 15 corresponds to that of a single layer (about 3 .mu.m)
formed under the condition of producing a magnetic layer. Actually,
continuously formed magnetic layers are highly likely to contain an
excess amount of oxygen of about 0% to about 3% by atomic weight
due to the influence, for example, residual oxygen in the course of
production of an intermediate layer.
[0276] By adding the additives as shown in FIGS. 10 through 15 and
varying the amount of oxygen or nitrogen, a magnetic thin film
having soft magnetic characteristics more outstanding than those of
a Fe single layer can be obtained.
[0277] In the present example, the magnetic thin films which mainly
contain Fe are examined. However, even in the case where Fe is
replaced by FeCo or FeCoNi, outstanding soft magnetic
characteristics are obtained immediately after formation of a film
to the completion of heat treatment at about 300.degree. C.
[0278] In summary, assuming that the composition of the
intermediate layer of the magnetic thin film of the present
invention is expressed by
(M.sub.2.alpha..sub.2X.sub.2.beta..sub.2).sub.100-.delta..sub.2A.sub.2.de-
lta..sub.2 (where .alpha..sub.2, .beta..sub.2, and .delta..sub.2
represent % by atomic weight; M.sub.2 is at least one magnetic
metal selected from the group consisting of Fe, Co, and Ni; X.sub.2
is at least one selected from the group consisting of Mg, Ca, Sr,
Ba, Si, Ge, Sn, Al, Ga, and transition metals excluding M.sub.1;
A.sub.2 is at least one selected from the group consisting of O and
N), when the composition is in a range represented as follows and
M.sub.1=M.sub.2 and X.sub.1=X.sub.2:
[0279] 0.1.ltoreq..beta..sub.2.ltoreq.80
[0280] .alpha..sub.2+.beta..sub.2=100
[0281] .delta..sub.1.ltoreq..delta..sub.2.ltoreq.67
[0282] outstanding soft magnetic characteristics are obtained.
[0283] Furthermore, according to the method for producing a
magnetic thin film of the above-mentioned structure by changing the
concentration of oxygen/oxygen plasma or nitrogen/nitrogen plasma
in a vapor growth apparatus as in the present example, a magnetic
layer and an intermediate layer of a magnetic thin film, a magnetic
layer, an intermediate layer and a high-resistant layer of a
magnetic multilayer, and a magnetic layer and an intermediate layer
of a high-resistant magnetic film can be produced by using the same
source for supplying film formation material. This allows
miniaturization of a growth apparatus and high-speed formation of a
film.
Example 5
[0284] In the present example, a magnetic thin film and a
high-resistant layer are formed on top of the other. The results
obtained by examining the composition and thickness of a
high-resistant layer in a magnetic multilayer will be shown.
[0285] First, a magnetic layer, an intermediate layer, and a
high-resistant layer are examined in the case of using the same
target.
[0286] The experimental conditions are as follows:
[0287] Substrate: non-magnetic ceramic substrate
[0288] Substrate temperature: room temperature to about 100.degree.
C.
[0289] Target of a magnetic multilayer: FeSiAl alloy target for a
magnetic layer, an intermediate layer, and a high-resistant
layer
[0290] Discharge gas pressure: about 8 mTorr
[0291] Discharge electric power: about 300 W
[0292] Sputtering gas: Ar for a magnetic layer
[0293] Ar+O.sub.2 for an intermediate layer (where an oxygen flow
ratio O.sub.2/(Ar+O.sub.2) is about 20%)
[0294] Ar+O.sub.2 for a high-resistant layer (where an oxygen flow
ratio O.sub.2/(Ar+O.sub.2) is about 20%), formed in a uniaxial
magnetic field of about 100 Oe
[0295] The composition of a single layer produced in an atmosphere
of Ar alone in the present example is about
Fe.sub.96.5Si.sub.3.0Al.sub.0.5.
[0296] FIG. 16 shows soft magnetic characteristics obtained by
changing the thickness of a magnetic thin film and the thickness of
a high-resistant layer under the condition that the thickness of a
magnetic layer is about 48.5 nm and the thickness of an
intermediate layer is about 1.5 nm. The total thickness of each
magnetic multilayer is about 4 .mu.m.
[0297] In Examples shown in FIG. 16, each magnetic multilayer has a
magnetic permeability of about 500 or more at about 100 MHz and
about 400 or more at about 300 MHz, and has Bs of about 1.7 T or
more. Each magnetic multilayer is provided with uniaxial anisotropy
of about 5 Oe. In Examples qa through qd, it is considered that
insulation is substantially eliminated in an intermediate layer of
about 10 nm. On the other hand, in Comparative Example qd, it is
considered that insulation between magnetic layers is not
eliminated in an intermediate layer of about 1.5 nm due to the
frequency dependence of magnetic permeability. Furthermore, in
Comparative Examples qb and qc, it is easily understood that a
high-resistant layer of about 50 nm sufficiently functions for
insulation; however, sufficient magnetostatic binding does not
occur in the magnetic thin film including a thick high-resistant
layer, so that soft magnetic characteristics are poor and Bs is
low.
[0298] Next, a magnetic multilayer is examined, in which a
high-resistant layer is produced by using an Al or Si target under
the condition that the same magnetic layer and intermediate layer
as those described above are used.
[0299] The experimental conditions are the same as those in the
above except for the conditions of producing a high-resistant
layer. Only the differences will be shown below.
Comparative Example ra
[0300] Target: FeSiAl alloy target for a magnetic layer, an
intermediate layer, and a high-resistant layer
Example ra
[0301] Target: FeSiAl alloy target for a magnetic layer and an
intermediate layer
[0302] Al for a high-resistant layer
Example rb
[0303] Target: FeSiAl alloy target for a magnetic layer and an
intermediate layer
[0304] Si for a high-resistant layer
Example rc
[0305] Target: FeSiAl alloy target for a magnetic layer and an
intermediate layer
[0306] FeSiAl alloy target and Al target are simultaneously
discharged for a high-resistant layer
[0307] Sputtering gas:
[0308] High-resistant layer of Comparative Example ra: Ar+O.sub.2
(where an oxygen flow ratio O.sub.2/(Ar+O.sub.2) is about 20%)
[0309] High-resistant layer of Example ra: an Al layer
(low-resistant layer) is oxidized in an atmosphere of oxygen
plasma
[0310] High-resistant layer of Example rb: a Si layer
(low-resistant layer) is oxidized in an atmosphere of oxygen
plasma
[0311] High-resistant layer of Example rc: a
Fe.sub.90Si.sub.3Al.sub.7 layer (low-resistant layer) produced by
simultaneous discharge is oxidized in an atmosphere of oxygen
plasma
[0312] The above-mentioned high-resistant layers are formed in a
uniform magnetic field of about 100 Oe.
[0313] FIG. 17 shows soft magnetic characteristics depending upon
the kind of a high-resistant layer under the conditions that the
thickness of a magnetic layer is about 48.5 nm, the thickness of an
intermediate layer is about 1.5 nm, the thickness of a magnetic
thin film is about 500 nm, and the total thickness of a magnetic
multilayer is about 4 .mu.m.
[0314] Any film shown in FIG. 17 is provided with uniaxial
anisotropy of about 13 to about 14 Oe. In Comparative Example ra, a
high-resistant layer is produced by introducing oxygen during
formation of a film; however, the high-resistant film does not
sufficiently insulate magnetic thin films due to the frequency
characteristics of magnetic permeability. This may be caused by the
following: the high-resistant film does not have sufficiently high
resistance as being an oxide film mainly containing Fe.
Furthermore, in any of the magnetic multilayer of Examples shown in
FIG. 17, the high-resistant layer insulates magnetic thin films,
and a magnetic permeability is increased. This may be because an
electrostatic binding effect is exhibited due to small thickness of
the high-resistant layer. Soft magnetic characteristics of Example
rc are more outstanding than those of Examples ra and rb.
[0315] In summary, assuming that magnetic thin films and a
high-resistant layer are alternately formed, and the thickness of
the magnetic thin film is T.sub.3 and the thickness of the
high-resistant layer is T.sub.4, a magnetic multilayer which
satisfies the following conditions will have outstanding
high-frequency characteristics and high Bs.
[0316] 100 nm.ltoreq.T.sub.3.ltoreq.1000 nm
[0317] 2 nm.ltoreq.T.sub.4.ltoreq.50 nm
[0318] 10.ltoreq.T.sub.3/T.sub.4.ltoreq.500
[0319] In the magnetic multilayer, assuming that the magnetic
layer, the intermediate layer, and the high-resistant layer have
compositions represented by M.sub.1X.sub.1A.sub.1,
M.sub.2X.sub.2A.sub.2, and M.sub.3X.sub.3A.sub.3, respectively
(M.sub.1, M.sub.2, and M.sub.3 are at least one magnetic metal
selected from the group consisting of Fe, Co, and Ni; X.sub.1,
X.sub.2, and X.sub.3 are at least one selected from the group
consisting of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and transition
metals excluding the magnetic metal; A.sub.1 to A.sub.3 represent
at least one selected from the group consisting of O and N), when
the conditions: M.sub.1=M.sub.2=M.sub.3 and X.sub.1=X.sub.2=X.sub.3
are satisfied, outstanding soft magnetic characteristics and high
Bs can be obtained even in the case where the total film thickness
is relatively large.
[0320] According to a method for producing a high-resistant layer
of the magnetic multilayer with the above-mentioned structure,
including the steps of: forming a low-resistant layer containing at
least one selected from the group consisting of Mg, Ca, Sr, Ba, Si,
Ge, Sn, Al, and Ga in an amount of about 10% by atomic weight or
more on a magnetic thin film or a magnetic layer; and oxidizing or
nitriding the low-resistant layer in an atmosphere of oxygen/oxygen
plasma or nitrogen/nitrogen plasma, a high-resistant layer which is
relatively thin and has outstanding insulation characteristics can
be produced. The low-resistant layer may be made of one of Mg, Ca,
Sr, Ba, Si, Ge, Sn, Al and Ga, or may be an alloy layer thereof.
For example, the low-resistant layer may be made of Al, Si, an AlTi
alloy, or a Fe.sub.90Si.sub.10 alloy. Particularly, an element
selected from the group consisting of Si, Al, Ti, and Cr is likley
to be dissolved in a solid state with magnetic metal. Thus, such an
element is preferable in the case where the low-resistant layer is
made of a magnetic alloy.
[0321] Referring to FIGS. 18A through 18E and FIGS. 19A through
19C, a method for producing a high-resistant layer will be
described. FIGS. 18A through 18D illustrate a method for producing
a high-resistant layer. FIG. 18E is a flow chart illustrating a
method for producing a high-resistant layer. FIGS. 19A through 19C
illustrate another method for producing a high-resistant layer.
[0322] Referring to FIGS. 18A through 18E, a magnetic thin film 182
is formed on a substrate 181 (FIG. 18A). A low-resistant layer 183
containing at least one of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and
transition metals excluding the above-mentioned M.sub.1 in an
amount of about 10% by atomic weight is formed on the magnetic thin
film 182 (FIG. 18B, Step S181 in FIG. 18E).
[0323] The low-resistant layer 183 is oxidized or nitrided in an
atmosphere of oxygen, nitrogen, oxygen plasma, and nitrogen plasma,
whereby a high-resistant layer 183A is formed (FIG. 18C, Step S182
in FIG. 18E).
[0324] The magnetic thin film 182 may be a magnetic layer. The
magnetic thin film 182 and the high-resistant layer 183A may be
multi-layered by repeatedly, alternately forming the magnetic thin
film 182 and the high-resistant layer 183A on the high-resistant
layer 183A (FIG. 18D).
[0325] Referring to FIGS. 19A through 19C, another method for
producing a high-resistant layer will be described. The magnetic
thin film or the magnetic layer may contain oxygen-compatible
elements. A magnetic thin film 192 containing an oxygen-compatible
element such as Si, Al, Ti, and Cr is formed on a substrate 191
(FIG. 19A). A low-resistant layer 193 containing at least one
selected from the group consisting of Mg, Ca, Sr, Ba, Si, Ge, Sn,
Al, Ga, and transition metals excluding the above-mentioned M.sub.1
in an amount of about 10% by atomic weight or more is formed on the
magnetic thin film 192.
[0326] The low-resistant layer 193 is oxidized or nitrided in an
atmosphere of oxygen/oxygen plasma and nitrogen/nitrogen plasma,
whereby a high-resistant layer 193A is formed (FIG. 19B).
[0327] The magnetic thin film 192 may be a magnetic layer. The
magnetic thin film 192 and the high-resistant layer 193 may be
multi-layered by repeatedly, alternately forming the magnetic thin
film 192 and the high-resistant layer 193 on the high-resistant
layer 193 (FIG. 19C).
Example 6
[0328] The present example shows the results obtained by examining
the composition of a high-resistant magnetic film with a
resistivity of about 80 .mu..OMEGA.cm or more and a magnetic
multilayer with high resistivity obtained by layering
high-resistant magnetic films.
[0329] The experimental conditions are as follows:
[0330] Substrate: non-magnetic ceramic substrate
[0331] Substrate temperature: room temperature to about 100.degree.
C.
[0332] Target: complex target in which a metal, semi-metal, or
oxide chip is disposed on a Fe or FeCo target. The same target is
used for a magnetic layer and an intermediate layer.
[0333] Discharge gas pressure: about 8 mTorr
[0334] Discharge electric power: about 300 W
[0335] Sputtering gas:
[0336] High-resistant magnetic film
[0337] Ar+(O.sub.2)+(N.sub.2) (where oxygen flow ratio
O.sub.2/(Ar+O.sub.2) is about 0% to about 5%, and nitrogen flow
ratio N.sub.2/(Ar+N.sub.2) is about 20% (only high-resistant
magnetic films with nitrogen added thereto)), formed in a uniform
magnetic field of about 100 Oe
[0338] High-resistant magnetic multilayer
[0339] Magnetic layer: Ar+(O.sub.2)+(N.sub.2) (where oxygen flow
ratio O.sub.2/(Ar+O.sub.2) is about 0% to about 5%, and nitrogen
flow ratio N.sub.2/(Ar+N.sub.2) is about 20% (only high-resistant
magnetic films with nitrogen added thereto)), formed in a uniform
magnetic field of about 100 Oe
[0340] Intermediate layer: Ar+O.sub.2 (where oxygen flow ratio
O.sub.2/(Ar+O.sub.2) is fixed to be about 20%), formed in no
magnetic field
[0341] Sputtering gases with the above-mentioned flow ratios are
alternately switched during formation of a film.
[0342] FIG. 20 shows soft magnetic characteristics and compositions
of high-resistant magnetic films after heat treatment at about
250.degree. C. in a vacuum. The thickness of each high-resistant
magnetic film is about 4 .mu.m.
[0343] The high-resistant magnetic films of Examples shown in FIG.
20 exhibit a high resistance of about 80 .mu..OMEGA.cm or more,
although a resistivity is slightly decreased after heat treatment,
compared with the case immediately after formation of the films. As
is understood from the Examples shown in FIG. 20, when the
high-resistant magnetic film is represented by M.alpha.X.beta.
(N.delta.O.epsilon.).gamma. (where .alpha., .beta., .gamma.,
.delta., and .epsilon. represent % by atomic weight; M is at least
one magnetic metal selected from the group consisting of Fe, Co,
and Ni; and X is at least one selected from the group consisting of
Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and transition metals excluding
the above-mentioned M), assuming that a chemical formula when X
becomes a nitride having the lowest nitride generation free energy
and a chemical formula when X becomes a nitride having the lowest
oxide generation free energy, it is important that the following
range should be satisfied:
[0344] .alpha.+.beta.+.gamma.=100
[0345] 45.ltoreq..alpha..ltoreq.78
[0346] .delta.+.epsilon.=100
[0347]
1<100.times..gamma./.beta./(m.times..delta.+n.times..epsilon.)&l-
t;2.5
[0348] Furthermore, the shortest diameter of an average crystal
grain is about 20 nm or less.
[0349] Next, high-resistant magnetic films are used as magnetic
layers, and intermediate layers are produced by using the same
target as that of each high-resistant magnetic film with an oxygen
flow ratio of about 20%. The magnetic layers each having a
thickness of about 500 nm and the intermediate layers each having a
thickness of about 500 nm are alternately formed to obtain magnetic
multilayers. The magnetic multilayer with high resistivity is
formed into strips with a width of about 1 .mu.m and a length of
about 1 mm by a focused ion beam (FIB), and the strips are measured
for magnetic permeability at a high frequency. Furthermore, as
Comparative Examples, a high-resistant magnetic film is formed into
the same shape as that of the magnetic multilayer, in which the
thickness of each magnetic layer is about 100 nm and the thickness
of each intermediate layer is about 5 nm. FIG. 21 shows soft
magnetic characteristics obtained after heat treatment at about
250.degree. C.
[0350] As is understood from the results shown in FIG. 21, a
high-resistant magnetic film formed into a relatively minute shape
exhibits an increased magnetic permeability at a high frequency by
being layered on an intermediate layer having a higher oxygen
concentration, and such a layered structure is effective for a
magnetic device subjected to minute processing such as a thin film
head.
[0351] As described above, a thin film head having more outstanding
high-frequency characteristics can be produced by using a magnetic
multilayer with high resistivity having a structure in which
magnetic layers and intermediate layers are alternately formed.
Each magnetic layer is made of a high-resistant magnetic film with
the above-mentioned structure and has a composition represented by
M.sub.1m1X.sub.1n1A.sub.1q- 1, and each intermediate layer has a
composition represented by M.sub.2m2X.sub.2n2A.sub.2q2 (where m1,
n1, q1, m2, n2, and q2 represent % by atomic weight; M.sub.1 and
M.sub.2 are at least one magnetic metal selected from the group
consisting of Fe, Co, and Ni; X.sub.1 and X.sub.2 are at least one
selected from the group consisting of Mg, Ca, Sr, Ba, Si, Ge, Sn,
Al, Ga, and transition metals excluding the magnetic metal; and
A.sub.1 and A.sub.2 are at least one selected from the group
consisting of O and N) the following expressions are satisfied:
[0352] M.sub.1=M.sub.2, X.sub.1=X.sub.2
[0353] q1<q2
[0354] In the present example, sputtering is used; however, the
above-mentioned films can be produced by using reactive vapor
deposition.
Example 7
[0355] The present example shows recording characteristics obtained
by applying a magnetic thin film of the present invention to a
recording magnetic pole of a thin film head.
[0356] The structure of a thin film head used in the present
example is as follows:
[0357] Recording medium: about 2200 Oe
[0358] Recording gap: about 0.2 .mu.m
[0359] Recording frequency: about 100 MHz
[0360] Number of turns: about 42
[0361] Thicknesses of upper and lower magnetic poles: about 4 .mu.m
each
[0362] Recording current: fixed to be about 5 mA
[0363] Permalloy (NiFe) deposited by plating is used for films of
Comparative Examples. Each magnetic thin film of Examples includes
the following layers: magnetic layers Fe.sub.94.0Si.sub.6.0 (about
100 nm per layer) and intermediate layers:
(Fe.sub.0.93Si.sub.0.7).sub.XO.sub.100-X (about 5 nm per layer),
and each magnetic multilayer with high resistivity includes the
following layers: magnetic layers Fe.sub.69Mg.sub.13O.sub.18 (about
100 nm per layer) and intermediate layers
(Fe.sub.0.84Mg.sub.0.16).sub.XO.sub.100-X (about 5 nm per layer)
where 18<X.
[0364] Referring to FIGS. 22 to 30, a thin film head of the present
example will be described. In the drawings, a magnetic thin film is
represented by high Bs, and a magnetic multilayer are represented
by high .rho..
[0365] FIG. 22 shows a structure of a thin film head 220 of
Comparative Example ua (see FIG. 34). The thin film head 220
includes an upper magnetic pole 221, a lower magnetic pole 222, a
shield film 223, and a coil 224. The upper magnetic pole 221, the
lower magnetic pole 222, and the shield film 223 contain
Ni.sub.50Fe.sub.50.
[0366] FIG. 23 shows a structure of a thin film head 230 of Example
ua (see FIG. 34). The thin film head 230 includes an upper magnetic
pole 231, a lower magnetic pole 232, a shield film 233, and a coil
234. The upper magnetic pole 231, the lower magnetic pole 232, and
the shield film 233 respectively contain a magnetic thin film.
[0367] FIG. 24 shows a structure of a thin film head 240 of Example
ub (see FIG. 34). The thin film head 240 includes an upper magnetic
pole 241, a lower magnetic pole 242, a shield thin film 243, and a
coil 244. The upper magnetic pole 241, the lower magnetic pole 242,
and the shield film 243 respectively contain a magnetic
multilayer.
[0368] FIG. 25 shows a structure of a thin film head 250 of Example
uc (see FIG. 34). The thin film head 250 includes an upper magnetic
pole 251, a lower magnetic pole 252, a shield film 253, and a coil
254. The upper magnetic pole 251 contains a magnetic thin film 251B
(thickness: about 0.5 .mu.m), and a magnetic multilayer with high
resistivity 251A (thickness: about 3.5 .mu.m). The lower magnetic
pole 252 contains a magnetic thin film 252B (thickness: about 0.5
.mu.m), and a magnetic multilayer 252A (thickness: about 3.5
.mu.m). The shield film 253 contains a magnetic multilayer.
[0369] FIG. 26 shows a structure of a thin film head 260 of Example
ud (see FIG. 34). The thin film head 260 includes an upper magnetic
pole 261, a lower magnetic pole 262, a shield film 263, and a coil
264. The upper magnetic pole 261 contains a magnetic thin film 261B
(maximum thickness: about 4 .mu.m), and a magnetic multilayer with
high resistivity 261A (maximum thickness: about 4 .mu.m). The lower
magnetic pole 262 contains a magnetic thin film 262B (thickness:
about 0.5 .mu.m), and a magnetic multilayer with high resistivity
262A (thickness: about 3.5 .mu.m). The shield film 263 contains a
magnetic multilayer with high resistivity.
[0370] FIG. 27 shows a structure of a thin film head 270 of Example
ue (see FIG. 34). The thin film head 270 includes an upper magnetic
pole 271, a lower magnetic pole 272, a shield film 273, and a coil
274. The upper magnetic pole 271 contains a magnetic thin film 271B
(thickness: about 0.5 .mu.m) and a magnetic multilayer with high
resistivity 271A (thickness: about 3.5 .mu.m). The lower magnetic
pole 272 contains a magnetic thin film 272B (thickness: about 0.5
.mu.m), and a magnetic multilayer with high resistivity 272A
(thickness: about 3.5 .mu.m). The shield film 273 is formed of a
magnetic multilayer with high resistivity.
[0371] FIG. 28 shows a structure of a thin film head 280 of Example
uf (see FIG. 34). The thin film head 280 includes an upper magnetic
pole 281, a lower magnetic pole 282, a shield film 283, and a coil
284. The upper magnetic pole 281 contains a magnetic thin film 281B
(thickness: about 0.5 .mu.m), and a magnetic multilayer with high
resistivity 281A (thickness: about 3.5 .mu.m). The lower magnetic
pole 282 is formed of a magnetic multilayer with high resistivity
(thickness: about 4 .mu.m). The shield film 283 is formed of a
magnetic multilayer with high resistivity.
[0372] FIG. 29 shows a structure of a thin film head 290 of Example
ug (see FIG. 34). The thin film head 290 includes an upper magnetic
pole 291, a lower magnetic pole 292, a shield film 293, and a coil
294. The upper magnetic pole 291 contains a magnetic thin film 291B
(maximum thickness: about 4 .mu.m), and a magnetic multilayer with
high resistivity 291A (maximum thickness: about 4 .mu.m). The lower
magnetic pole 292 is formed of a magnetic multilayer with high
resistivity (thickness: about 4 .mu.m). The shield film 293 is
formed of a magnetic multilayer with high resistivity.
[0373] FIG. 30 shows a structure of a thin film head 300 of Example
uh (see FIG. 34). The thin film head 300 includes an upper magnetic
pole 301, a lower magnetic pole 302, a shield film 303, and a coil
304. The upper magnetic pole 301 contains a magnetic thin film 301B
(thickness: about 0.5 .mu.m), and a magnetic multilayer with high
resistivity 301A (thickness: about 3.5 .mu.m). The lower magnetic
pole 302 is formed of a magnetic multilayer with high resistivity
(thickness: about 4 .mu.m). The shield film 303 is formed of a
magnetic multilayer with high resistivity.
[0374] FIG. 31 shows a structure of a DC magnetron sputtering
device 320 for producing films. The DC magnetron sputtering device
320 includes a rotator 361 which rotates with respect to a central
axis 361A. A substrate 250 onto which a film is formed is provided
on the rotator 361. The DC magnetron sputtering device 320 includes
a high Bs vapor deposition source 261BS for forming a high Bs film
on the substrate 250, and a high P vapor deposition source 261AS
for forming a high p film on the substrate 250. A target size, a
discharge gas pressure, and a substrate temperature are set to be
about 5 inches, about 5 mTorr, and room temperature,
respectively.
[0375] As shown in FIGS. 32A through 32C, for example, in the case
of a thin film head 250 of Example uc, particularly when the upper
magnetic pole 251 is formed on the coil 254, the magnetic thin film
251B (high Bs film) and the magnetic multilayer with high
resistivity 251A (high p film) are successively formed by using the
high Bs vapor deposition source 251BS and the high p vapor
deposition source 251AS.
[0376] As shown in FIGS. 33A through 33C, in the thin film head 260
of Example ud, the magnetic thin film 261B (high Bs film) is formed
on the front side of a recording gap, and the magnetic multilayer
with high resistivity 261A (high P film) is formed on the back side
of the recording gap.
[0377] As shown in FIG. 34, compared with a thin film head using
conventional magnetic poles made of permalloy, a thin film head
using the magnetic thin film and the magnetic multilayer with high
resistivity of the present invention as magnetic poles exhibits
outstanding overwrite characteristics at a low recording current.
This is due to the magnetic material used in the present invention,
which has a high saturated magnetic flux density or high specific
resistance, and has outstanding soft magnetic characteristics, with
a domain structure controlled.
[0378] Accordingly, outstanding overwrite characteristics are
exhibited at a relatively low recording current in a thin film head
having a structure in which at least an upper magnetic pole is
composed of a magnetic multilayer with high resistivity (specific
resistance: about 80 .mu..OMEGA.cm or more) and a magnetic thin
film or a magnetic multilayer with high resistivity having the
above-mentioned structure, and the magnetic thin film or the
magnetic multilayer is formed at least in the vicinity of a
recording gap at an end portion of the upper magnetic pole; and a
thin film head having a structure in which a magnetic thin film or
a magnetic multilayer with the above-mentioned structure is formed
at least on a recording gap, and a magnetic multilayer with high
resistivity (specific resistance: about 80 .mu..OMEGA.cm or more)
is formed on the magnetic thin film or the magnetic multilayer.
These thin film heads can be obtained by a relatively easy
process.
Example 8
[0379] The present example describes a method for producing a
recording magnetic pole of a thin film head while changing a
relative position between a thin film head and a target.
[0380] FIGS. 35A through 35C and FIGS. 36A through 36C illustrate
other methods for producing a thin film head using a magnetic thin
film and a magnetic multilayer with high resistivity of the present
invention. FIG. 36D is a flow chart illustrating other methods for
producing a thin film head using a magnetic thin film and a
magnetic multilayer with high resistivity. In the present example,
the DC magnetron sputtering device 320 shown in FIG. 31 is used,
and a target size, a discharge gas pressure, and a substrate
temperature are set to be about 5.times.15 inches, about 5 mTorr,
and about 20.degree. C., respectively.
[0381] In FIGS. 35A through 35C, FIGS. 36A through 36C, and FIG.
36D, Fe.sub.94Si.sub.6 is used as target material. First, a target
is fixed, and a substrate is reciprocated in a shorter direction of
the target (S361), whereby at least one of a magnetic thin film, a
magnetic multilayer, a high-resistant magnetic film, and a magnetic
multilayer with high resistivity is formed (S362). Herein, the
shorter direction refers to a depth direction DD (FIG. 35A) of an
upper magnetic pole of a thin film head. A movement speed is set to
be about 2 rpm, and a change angle of movement is in a range of
about .+-.0.degree. to about 45.degree.. In the device used in the
present example, when the change angle of movement of the substrate
exceeds about 20.degree. to about 30.degree., a film formation
speed becomes about 1/5 or less that of the case where the change
angle is 0.degree.. More specifically, as the change angle
increases, a distance between the target and the substrate is
increased, and the number of sputtering particles scattering from
the target to the substrate is greatly decreased.
[0382] The films thus obtained are examined for soft magnetic
characteristics, and their cross-sectional structures are observed
with a TEM. FIG. 37 shows the results.
[0383] As shown in FIG. 37, compared with the case where the
relative position between the target and the substrate is fixed, in
the case where the target is moved in a relative manner, a
magnetization difficult axis of a film is formed in a direction in
which the target is moved, and soft magnetic characteristics are
enhanced. The direction of the magnetization difficult axis is not
related to the direction of a leakage magnetic field on the target,
and depends upon the method for forming a film of the present
example. When the cross-section of the film of Comparative Example
va is observed with a TEM, column-shaped or needle-shaped crystal
grains are formed. On the other hand, when the cross-section of the
film of Example vc is observed with a TEM, a layered structure of a
microcrystalline layer of about 3 nm and an amorphous layer of
about 1 to about 2 nm is formed. More specifically, in spite of the
fact that films are formed under the same sputtering conditions, by
changing a positional relationship between the substrate and the
target in a particular direction, a film formation speed is changed
in a cyclic manner, energy or an average free passage of sputtering
particles incident upon the substrate is changed, an angle at which
sputtering particles are incident upon the substrate is changed,
and the like. As a result, the above-mentioned layered structure is
naturally formed.
[0384] Furthermore, the amorphous layer contains more oxygen than
the microcrystalline layer. Stress in a film obtained from a
warpage amount of the substrate is decreased as the cycle of the
layered structure becomes shorter. This is because films are formed
with a large change angle at a constant movement speed.
Example 9
[0385] A hard disk drive using a thin film head of the present
invention will be described with reference to FIGS. 38 and 39.
[0386] FIG. 38 is a side view of a hard disk drive 110 using a thin
film head of the present example. FIG. 39 is a plan view
thereof.
[0387] The hard disk drive 110 includes a slider 120 for holding a
thin film head of the present invention, a head supporting
mechanism 130 for supporting the slider 120, an actuator 114 for
tracking a thin film head via the head supporting mechanism 130,
and a disk drive motor 112 for driving a disk 116. The head
supporting mechanism 130 includes an arm 122 and a suspension
124.
[0388] The disk drive motor 112 drives the disk 116 at a
predetermined speed. The actuator 114 moves the slider 120 holding
the thin film head in a radial direction across the surface of the
disk 116 in such a manner that the thin film head can access a
predetermined data track of the disk 116. The actuator 114 is
typically a linear or rotary voice coil motor.
[0389] The slider 120 holding the thin film head is, for example,
an air bearing slider. In this case, the slider 120 comes into
contact with the surface of the disk 116 upon boot-up or halting of
the hard disk drive 110. When information is recorded onto or
reproduced from the hard disk drive 110, the slider 120 is
maintained on the surface of the disk 116 by an air bearing formed
between the rotating disk 116 and the slider 120. The thin film
head held on the slider 120 records information onto or reproduces
it from the disk 116.
[0390] As described above, by using a magnetic thin film, a
magnetic multilayer, a high-resistant magnetic film, and a magnetic
multilayer with high resistivity having the composition and
structure of the present invention, and a method for producing the
same, it is possible to provide a magnetic material which has
outstanding soft magnetic characteristics at a high frequency and
has a high saturated magnetic flux density or a high specific
resistance, even after being formed into a minute shape in a
process at a low temperature (i.e., about 300.degree. C. or less).
Furthermore, the magnetic thin film and the magnetic multilayer
have excellent processability to a minute shape, and can be layered
at a high speed. Still further, these films can be provided with
anisotropy without being heat-treated in a magnetic field.
Therefore, mass-production and reliability of magnetic devices
using these films are enhanced, and processing apparatuses and
vapor growth apparatuses can be produced easily at a low cost.
[0391] Furthermore, by using the magnetic thin film, the magnetic
multilayer, the high-resistant magnetic film, and the magnetic
multilayer with high resistivity of the present invention, thin
film heads for high-density recording, having outstanding
mass-productivity can be obtained. In addition, the power
consumption of an apparatus using such a thin film head can be
decreased, so that an information processing apparatus can be
miniaturized, rendered light-weight, and used continuously for a
long period of time.
[0392] Various other modifications will be apparent to and can be
readily made by those skilled in the art without departing from the
scope and spirit of this invention. Accordingly, it is not intended
that the scope of the claims appended hereto be limited to the
description as set forth herein, but rather that the claims be
broadly construed.
* * * * *