U.S. patent application number 09/725253 was filed with the patent office on 2001-03-15 for magnetic recording and reading device.
Invention is credited to Shiroishi, Yoshihiro.
Application Number | 20010000022 09/725253 |
Document ID | / |
Family ID | 16961193 |
Filed Date | 2001-03-15 |
United States Patent
Application |
20010000022 |
Kind Code |
A1 |
Shiroishi, Yoshihiro |
March 15, 2001 |
Magnetic recording and reading device
Abstract
A magnetic recording and reading device which has a transfer
rate of not less than 50 MB/s and which includes a magnetic
recording medium having an absolute value of normalized noise
coefficient per recording density of not more than
2.5.times.10.sup.-8 (.mu.Vrms) (inch) (.mu.m).sup.0.5/(.mu.Vpp),
and a magnetic head which is mounted on an integrated circuit
suspension so that a total inductance is reduced to be not more
than 65 nH. The magnetic head has a magnetic core which is not more
than 35 .mu.m of length, a part of the magnetic core being formed
by a magnetic film having a resistivity exceeding at least 50
.mu..OMEGA.cm or by a multilayer film consisting of a magnetic film
and an insulating film. A fast R/W-IC having a line width of not
more than 0.35 .mu.m is also provided. The magnetic head is
provided with a reading element comprising one of a giant
magnetoresistance effect element and a thin film having
tunneling-magnetoresistance effect, with an effective track width
of not more than 0.9 .mu.m, and performs the reading of magnetic
information at an areal density of not less than 5 Gb/in.sup.2.
Inventors: |
Shiroishi, Yoshihiro;
(Hachioji-shi, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
16961193 |
Appl. No.: |
09/725253 |
Filed: |
November 29, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09725253 |
Nov 29, 2000 |
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09377189 |
Aug 19, 1999 |
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Current U.S.
Class: |
360/324 ;
360/97.11; G9B/5; G9B/5.086; G9B/5.24; G9B/5.288 |
Current CPC
Class: |
G11B 5/3909 20130101;
G11B 2005/3996 20130101; G11B 5/73911 20190501; G11B 2005/0002
20130101; G11B 5/73919 20190501; G11B 5/313 20130101; G11B 5/3967
20130101; G11B 5/484 20130101; G11B 5/66 20130101; B82Y 25/00
20130101; G11B 5/73923 20190501; G11B 5/09 20130101; G11B 5/73921
20190501; G11B 5/73913 20190501; G11B 5/656 20130101; B82Y 10/00
20130101; G11B 2005/0005 20130101; G11B 5/00 20130101 |
Class at
Publication: |
360/324 ;
360/97.01 |
International
Class: |
G11B 005/39 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 20, 1998 |
JP |
10-233827 |
Claims
What is claimed is:
1. A magnetic recording and reading device of which transfer rate
is not less than 50 MB/s and which comprises: a magnetic recording
medium having an absolute value of normalized noise coefficient per
recording density of not more than 2.5.times.10.sup.-8 (.mu.Vrms)
(inch) (.mu.m).sup.0.5/(.mu.Vpp); a magnetic head which is mounted
on an integrated circuit suspension so that a total inductance is
reduced to be not . more than 65nH and having a magnetic core which
is not more than 35 .mu.m of length, a part of the magnetic core
being formed by a magnetic film having a resistivity exceeding at
least 50 .mu..OMEGA.cm or by a multilayer film consisting of a
magnetic film and an insulating film; and a fast R/W-IC having a
line width of not more than 0.35 .mu.m; wherein said magnetic head
is provided with a reading element comprising one of a giant
magnetoresistance effect element and a thin film having
tunneling-magnetoresistance effect, with an effective track width
of not more than 0.9 .mu.m, and performs reading of magnetic
information at an areal density of not less than 5 Gb/in.sup.2.
2. A magnetic recording and reading device according to claim 1,
wherein said magnetic head has a magnetic pole length of not more
than 50 .mu.m.
3. A magnetic recording and reading device according to claim 1,
wherein said R/W-IC is installed in a position within 2 cm from a
rear end of said magnetic head.
4. A magnetic recording and reading device according to claim 1,
wherein said magnetic recording medium has a magnetic layer which
comprises at least one metal element selected from the group
consisting of Co, Fe and Ni as a primary component, at least two
elements selected from a second group consisting of Cr, Mo, W, V,
Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and at least one element
selected from a third group consisting La, Ce, Pr, Nd, Pm, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B.
5. A magnetic recording and reading device according to claim 4,
wherein said magnetic layer of said magnetic recording medium is an
amorphous material.
6. A magnetic recording and reading device according to claim 4,
wherein said magnetic layer of magnetic recording medium is
multilayered composed of a magnetic thin film and a non-magnetic
intermediate layer comprising at least one kind of element selected
from the group consisting of Cr, Mo, W, V, Nb, Zr, Hf, Ti, Ge, Si,
Co, Ni, C and B as a primary component.
7. A magnetic recording and reading device according to claim 1,
wherein aid magnetic head is positioned by a rotary actuator in at
least two stages of coarse and fine movement adjustments.
Description
BACKGROUND OF THE INVENTION
1. The present invention relates to a magnetic disc device used in
computers, information storage devices and so on, a magnetic
storage device used in such information home appliances as digital
VTRs, and a magnetic recording, and and, more particularly, to a
magnetic recording and reading device suitable for realizing
high-speed recording and reading, and for high-density
recording.
2. Semiconductor memories, magnetic memories, etc., are used in the
storage or recording devices of information equipment.
Semiconductor memories are used in internal primary storage in the
light of high-speed accessibility and magnetic memories are used in
external secondary storages in the light of a high capacity, low
cost and nonvolatile property. Magnetic disk devices, magnetic
tapes and magnetic cards are the main current in magnetic memories.
A magnetic recording portion which produces a strong magnetic field
is used in order for writing magnetic information in recording
media, such as magnetic disks, magnetic tapes or magnetic cards.
Further, reading portions based on the magnetoresistance effect or
the electromagnetic induction effect are used in reading magnetic
information recorded at a high desisty. In recent years, for
reading, the gigant magnetoresistance effect and the tunneling
magnetoresistive effect have also begun to be examined. These
functional portions for recording and reading are both installed in
an input-output part which is called a magnetic head.
3. The basic configuration of a magnetic disk device is shown in
FIGS. 10A and 10B. FIG. 10A shows a plan view of the device and
FIG. 10B shows a vertical-sectional view of the device. Recording
media 101-1 to 101-4 are fixed to a hub 104 to be rotated by a
motor 100. In FIG. 10B shows one example which comprises four
magnetic disks 101-1 to 101-4 and eight magnetic heads 102-1 to
102-8. However, the magnetic disk device may comprise at least one
magnetic disk and at least one magnetic head. The magnetic heads
102-1 to 102-8 move on the rotating recording media. The magnetic
heads 102-1 to 102-8 are supported by a rotary actuator 103 via
arms 105-1 to 105-8. Suspensions 106-1 to 106-8 have function of
the pressing the magnetic heads 102 against the recording media
101-1 to 101-4 under a determined load, respectively. A given
electric circuit is needed for processing of reproduction signals
and for inputting and outputting of information. Recently, a signal
processing circuit in which waveform interference at high-density
is positively utilized, such as PRML (Partial Response Maximum
Likelihood) or EPRML (Extended PRML) which is an enhanced PRML, has
been adopted, contributing greatly to a high-density design. The
signal processing circuit is installed in a circuit board on a
cover 108, etc.
4. The functional portion for writing and reading information on a
magnetic head assembly is comprises components shown in FIG. 11A,
for example. A writing portion 111 is comprised of a spiral coil
116 between magnetic poles 117, 118 which are magnetically
connected with each other. The magnetic poles 117, 118 are both
composed of a magnetic film pattern, which are made of an NiFe
alloy, etc., respectively. The reading portion 112 comprises a
magnetoresistance element 113 made of an NiFe alloy, etc. and an
electrode 119 for applying a constant current or a constant voltage
to the element 113 and for detecting changes in resistance. The
magnetic pole 118, which is made of an NiFe alloy, etc. and serves
also as a magnetic shielding layer, is provided between the writing
and reading portions. There is further a shielding layer 115
underneath the magnetoresistance element 113. A reading resolution
is determined by the clearance distance between the shielding layer
115 and the magnetic pole 118 (serving also as another shielding
layer). The functional portion is formed on a magnetic head slider
1110 (FIG. 11B) via an underlayer 114 made of Al.sub.2O.sub.3, etc.
Incidentally, the magnetic head slider, which is provided with a
protection layer made of hard-carbon, etc. on the surface opposed
to the magnetic recording medium, is supported by a gimbal 1111 and
a suspension 1113, as shown in FIG. 11B. The magnetic head slider
moves relatively to the magnetic recording medium while floating
from the medium surface and, after positioning in an arbitrary
position by an arm 1114 connected to a motor, realizes the function
of writing or reading magnetic information via lead lines 1116 and
1115. With respect to the above function, there is also provided an
electric control circuit together with the aforementioned signal
processing unit or on the head carriage.
5. A detailed structure of a recording medium is schematically
shown in FIG. 12. As described in JP-A-3-16013, most of the
conventionally used recording media are produced by forming a
magnetic layer 123 made of a Co--Cr--Ta alloy, or a Co--Cr--Pt
alloy, etc. on a non-magnetic substrate made of Al plated with an
NiP alloy, a glass, a high-hardness ceramics, a polished Si or the
like, or a plastic substrate 121 by the sputtering method, or the
evaporation method, or the plating method, etc. Usually, an under
layer 122 made of Cr, or a Cr alloy, etc. for orientation control
of the magnetic layer is often formed on the substrate.
Furthermore, a protection film 124 made of diamond-like carbon
containing nitrogen and/or hydrogen, or SiO.sub.2 or SiN or
ZrO.sub.2, etc. is provided to ensure durability of sliding
resistance, and a lubricating film 125 made of perfluoro alkyl
polyether having an adsorptive or a reactive end group, or organic
fatty acids, etc. is provided.
6. In addition to the magnetic recording device, magneto-optic
recording devices that perform recording and reading on a magnetic
recording medium through the use of light have also been put to
practical use. The magneto-optic recording devices are classified
into one type in which recording is performed only by light
modulation and another type in which recording and reproduction are
performed by light with a modulated magnetic field. However, the
both types greatly rely on heat when recording and reading.
Therefore, according to such type of devices, it is impossible to
perform recording and reading in high data transfer rate and thus
they have been adopted mainly in backup systems, etc.
7. The importance of a storage device is determined by its storage
capacity and the speed during inputting-outputting operations. In
order to increase competitiveness of products, it is necessary for
the storage device to increase capacity by higher recording
density, higher rotational speed and higher data transfer rate than
those of the prior art. Thus, an important problem to be solved by
the present invention is to provide a device capable of recording
and reading at a high data transfer rate of not less than 50 MB/s
and, more preferably, that at a high density of not less than 5
Gb/in.sup.2. A magnetic recording medium capable of recording and
reading at a high frequency and capable of obtaining a high S/N
ratio at a high density and a magnetic head capable of generating a
sufficient magnetic recording field at a high frequency are
necessary for meeting the requirement.
8. In conventional magnetic recording media, there have been
proposed and actually carried out to reduce noise by refining
crystal grains in order to obtain a high S/N ratio at a high
density of about 1 to 3 Gb/in.sup.2, and by promoting segregation
of non-magnetic components at grain boundaries to reduce exchange
coupling among crystal grains as being taught in JP-A-63-148411,
JP-A-3-16013 and JP-A-63-234407 so as to make the coercive
squareness S* to not more than 0.85 and the rotational hysteresis
loss RH to the range of 0.4 to 1.3. Noise can be considerably
reduced by recording and reading at a data transfer rate of not
more than about 20 MB/s. However, when the magnetic recording was
carried out on that film media of the prior art at a high frequency
of not less than 50 MB/s, thermal fluctuation effects in fine
magnetic crystallines is remarkable due to weak exchange coupling
among crystal grains and the apparent coercive force is high
resulting in that it was impossible to record on it accurately.
Furthermore, even when recording is performed under a large current
with utilization of a modified recording circuit, etc., the
magnetic recording transition region is widened due to a broad
magnetic recording field resulting in that noise increases and/or
recorded information is lost when it was alowed to stand for a long
time.
SUMMARY OF THE INVENTION
9. An object of the present invention is to provide a low-noise
magnetic recording medium composed of fine crystal grains which is
capable of recording and reading at a high data transfer rate of
not less than 50 MB/s and further permits high-density recording at
not less than about 5 Gb/in.sup.2, a recording and reading magnetic
head with high reading sensitivity which is capable of sufficiently
sharp recording on the medium, and a magnetic recording device of a
high data transfer rate and high density which is realized by using
the magnetic recording medium and the magnetic head of the present
invention.
10. In order to achieve the above object, the present inventors
pushed forward studies on chemical compositions of magnetic
recording media, deposition processes and technologies related to
devices such as magnetic heads, and found out that the following
means are very effective.
11. There is proposed a magnetic recording medium with a magnetic
layer comprising at least one metal element selected from the group
consisting of Co, Fe and Ni as a primary component, at least two
elements selected from a second group consisting of Cr, Mo, W, V,
Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and at least one element
selected from a third group consisting of La, Ce, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B.
According to the magnetic recording medium, it is possible to
obtain a high S/N (signal-to-noise) ratio even under recording at
high data transfer rate of not less than 50 MB/s and to reduce the
absolute value of normalized noise coefficient per a unit
transition {square root}{square root over (Nd.sup.2-No.sup.2.)}
{square root}{square root over (Tw/)} (S0.D) (Nd: recorded media
noise, No: DC erase noise, Tw: effective read track width, S.sub.0:
isolated pulse output, D: recording density in the unit of flux
change per inch) to not more than 2.5.times.10.sup.-8 (.mu.Vrms)
(inch) (.mu.m).sup.0.5/(.mu.Vpp)- .
12. The invention can provide a magnetic recording device which can
perform recording at a high data transfer rate of not less than 50
MB/s by using the above magnetic recording medium, a magnetic
recording head and an R/W-IC having the following features; that
is, the magnetic recording head assembly is given a total
inductance reduced to not more than 65 nH because it has a magnetic
core length of not more than 35 .mu.m, because it is provided with
a magnetic film with a resistivity exceeding 50 .mu..OMEGA.cm or a
multilayer film composed of a magnetic film and an insulating film
in part of the magnetic core, and further because it is mounted on
an integrated circuit suspension; and the R/W-IC produced using a
process of a line width of not more than 0.35 .mu.m and is capable
of operating at high frequencies. Furthermore, the magnetic
recording device of the present invention can perform the reading
of magnetic information at a high density of not less than 5
Gb/in.sup.2 by using a magnetic head provided with a read element
having a giant magnetoresistance effect or a
tunneling-magnetoresistance effect and with an effective track
width of not more than 0.9 .mu.m.
13. Recording density can be increased about 20% by forming the
magnetic layer of the magnetic recording medium through a
non-magnetic intermediate layer comprising at least one element
selected from the group consisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf,
Ti, Ge, Si, Co, Ni, C and B as a primary component.
14. A magnetic recording and reading device of higher density can
be provided by performing magnetic recording immediately after heat
application to a magnetic recording medium through the use of a
semiconductor laser, etc. and performing reading with the aid of
the above giant magnetoresistance effect element or an element
having a tunneling-magnetoresistive thin film.
15. Furthermore, in order to shorten an access time and perform
positioning with higher accuracy, it is effective to adopt a rotary
type actuator to position the head in at least two stages of coarse
and fine movement adjustments.
16. The precent inventors pushed forward on read-and-write
properties of a magnetic recording medium as shown in FIG. 12,
which is fabricated by forming a magnetic layer of a Co alloy,
etc., a protective layer of C--N, etc., and a lubricating layer of
perfluoro-alkyl-polyether, etc., in this order, directly on a
non-magnetic substrate or via a non-magnetic underlayer which
comprises at least one element selected from the group consisting
of Cr, Mo, W, Ta, V, Nb, Ta, Ti, Ge, Si, Co and Ni as a primary
component, the above magnetic layer was formed by controlling film
deposition conditions, such as substrate temperature, atmosphere
and deposition rate, heat treatment conditions, compositions of
magnetic layer or under layer, a thickness of each layer,
crystalline, the number of layers, etc. At a recording density of 3
Gb/in.sup.2 and at 10 kprm, these magnetic media were evaluated
through the use of a conventional magnetic head with the MR element
as shown in FIGS. 11A and 11B on a conventional magnetic disk
device as shown in FIGS. 10A and 10B. As a result, the present
inventors found out that by giving the above magnetic layer of a
composition containing at least one metal element selected from the
group consisting of Co, Fe and Ni as a primary component, and at
least two elements selected from a second group consisting of Cr,
Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, it is possible
to refine crystal grains and reduce the exchange interaction among
crystal grains and also to reduce the absolute value of normalized
noise coefficient per recording density to not more than
3.times.10.sup.-8 (.mu.Vrms) (inch) (.mu.m).sup.0.5/(.mu.Vpp) even
when recording and reading are performed at a transfer rate of not
more than 20 MB/s of conventional technology. This effect was
remarkable especially during low-pressure, high-temperature and
high-rate film depositions or during film depositions at a high
pressure and a low deposition rate. Under other conditions,
however, this effect was good enough by optimizing compositions and
combinations.
17. On the other hand, in order to record at a high rate of not
less than 50 MB/s, it was necessary to use an R/W-IC (Read and
Write IC) which is capable of a high speed processing by putting
fine-pattern-width for not more than 0.35 .mu.m to partial use at
least and, in addition, it was necessary to develop a magnetic
recording head structure capable of generating a strong magnetic
recording field at a high rate in response to this fast driving
current. In order to prevent the deterioration of fast signals, it
is important that the IC be installed in a position as close to the
head as possible and it was desirable to reduce the distance to not
more than 2 cm. The present inventors examined magnetic pole and
head structures and materials for magnetic poles, and developed a
magnetic head assembly with a total inductance reduced to not more
than 65 nH in which the magnetic core length l.sub.1 of a magnetic
recording core composed of the lower magnetic pole 118 and the
upper magnetic pole 117 in FIG. 11A is not more than 35 .mu.m, and
which is provided with a magnetic film with a resistivity exceeding
50 .mu..OMEGA.cm or a multilayer film composed of a magnetic film
and an insulating film in part of the magnetic poles composing the
magnetic core, and which is mounted on a suspension 113 with an
integrated conductive line through insulator 1116. Recording
magnetic fields obtained by this magnetic head were evaluated with
the aid of a magnetic field SEM, MFM, etc. As a result, the present
inventors could ascertain that a sufficient magnetic field can be
generated even at a data transfer rate of not less than 50 MB/s,
and found out that recording at a transfer rate of not less than 50
MB/s is, in principle, possible. Materials for magnetic poles with
a resistivity exceeding 50 .mu..OMEGA.cm include, for example,
NiFe-base alloys, such as 42Ni--57Fe--1Cr, 46Ni--52Fe--2Cr,
43Ni--56Fe--1Mo, 51Ni--47Fe--2S and 54Ni--43Fe--3P, and amorphous
magnetic alloys, such as CoTaZr and CoNbZr. Examples of multilayer
film composed of a magnetic film and an insulating film include a
multilayer film composed of 89Fe--8Al--3Si and SiO.sub.2 and a
multilayer film composed of 80Ni--20Fe and ZrO.sub.2.
18. When recording and reading on the above medium at 50 MB/s
through the use of the magnetic head and circuit of the above
construction, satisfactory recording was incapable due to a bad
overwrite characteristic, etc. and besides noise increased twice or
three times. Thus, it became apparent that further ideas are
necessary for ensuring recording and reading both in high-density
and high data transfer rate. Here, signals were read through the
use of a conventional MR read element with a narrow track width of
2 .mu.m.
19. The reason for the above phenomenon was examined. The present
inventors considered that the above phenomenon is due to a bad
frequency response in the recording characteristic of the medium.
Therefore, the cause was analyzed by performing a simulation
through the use of a super computer, etc. and as a result, it
became evident that there is a problem in thermal fluctuations of
magnetization and spin damping during recording process. Therefore,
studies were carried out on medium additives capable of optimizing
thermal fluctuations and damping coefficient. As a result, the
present inventors found out that by adding at least one element
selected from a third group consisting of La, Ce, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B to the
composition of the above medium, it is possible to reduce the
absolute value of normalized noise coefficient per recording
density to not more than 2.5.times.10.sup.-8 (.mu.Vrms)(inch)
(.mu.m).sup.0.5/(.mu.Vpp) even when recording is performed at 50
MB/s. This effect was observed when the above elements were added
in amounts of not less than 0.1 at%. However, their addition in an
amount of 0.1 at% is sufficient. Addition in amounts of not more
than 0.1 at% was undesirable because of a remarkable decrease in
output. Furthermore, the effect was remarkable when rare earth
elements were added. The above effect was also ascertained in what
is called a granular type medium in which a non-magnetic substance,
such as SiO.sub.2 and ZrO.sub.2, and a magnetic material with a
high crystalline anisotropy constant, such as CoPt and CoNiPt, were
simultaneously formed by sputtering and the magnetic material with
a high crystalline anisotropy constant was precipitated and
dispersed by heat treatment at a temperature of about 300.degree.
C. to obtain the above composition. Furthermore, in a case where
the above magnetic layer is made of an amorphous magnetic
substance, the magnetic layer often has perpendicular anisotropy.
However, the same effect was also observed in this case.
Furthermore, in any of these instances, when the above magnetic
layer was formed via a non-magnetic intermediate layer containing
at least one element selected from the group consisting of Cr, Mo,
W, V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, C and B as a primary
component, noise could be remarkably reduced because of statistical
addition of signals and this was especially favorable for noise
reduction. Furthermore, what is especially noteworthy is that by
reducing the magnetic core length of the above magnetic head to not
more than 50 .mu.m, a sharp and strong magnetic field could be
generated with increased efficiency and recording on a medium with
a higher coercive force was possible. This is preferable because
higher densities can be obtained. Furthermore, by installing the
above R/W-IC near the suspension, the rise time of a recording
magnetic field could be made further shorter. This permitted sharp
recording and enabled medium noise to be relatively reduced.
Therefore, this is more preferable.
20. In order to perform recording and reading at a high density of
not less than 5 Gb/in.sup.2, it was necessary to perform the
reading of magnetic information through the use of a magnetic head
having an effective read-track width of not more than 0.9 .mu.m
with giant magnetoresistive effect or tunneling-magnetoresistive
effect, and performs the reading of magnetic information at a high
density of not less than 5 Gb/in.sup.2. By performing reading like
this, a signal-to-noise ratio of not less than 20 dB of the device
necessary for the operation of the device was obtained with the aid
of the signal processing method and it was necessary to combine the
magnetic head with signal processing such as EPRML or EEPRML,
trellis coding, ECCs, etc. Incidentally, the giant magnetoresistive
element (GMR) and tunneling magnetic head technologies are
disclosed in JP-A-61-097906, JP-A-02-61572, JP-A-04-35831,
JP-A-07-333015, JP-A-02-148643 and JP-A-02-218904. An effective
track width of not more than 0.9 .mu.m was realized by putting
lithography technology based on an i-line stepper or a KrF stepper,
FIB fabrication technology, etc. to full use.
21. The above system was a very epoch-making product as a magnetic
disk. However, the present inventors found out that recording can
be assisted by instantaneously heating a medium to the temperature
range of from about 50.degree.C. to 250.degree. C. with a magnetic
disk provided with a heat-generating portion and thereby reducing
the coercive force at a high frequency, and that this idea is
further effective. In other words, in this system the load put on
the recording portion and the material for recording magnetic poles
could be reduced, and recording at a high density of not less than
5 Gb/in.sup.2 and a high data transfer rate of not less than 50
MB/s was possible even with a recording track width of not more
than 0.9 .mu.m and even when a magnetic pole material with a
saturation magnetic flux density of 1 T was used. Thus, this was
especially advantageous.
22. With respect to this effect, access time can also be shortened
by performing magnetic recording immediately after heat application
to a magnetic recording medium and performing reading with the aid
of the above giant magnetoresistive element or element having a
tunneling-magnetoresistive effect. This is further preferable.
23. Furthermore, by using a semiconductor laser chip as the above
heat-generating portion, an effective head volume can be reduced
and high-speed positioning becomes possible. This is especially
preferable. In addition, in order to shorten access time and ensure
positioning with a higher accuracy, it is especially effective to
position the head by a rotary actuator method in at least two
stages of coarse and fine movement adjustments.
BRIEF DESCRIPTION OF THE DRAWINGS
24. FIG. 1 shows schematically the essential portion of a magnetic
recording medium of the invention;
25. FIG. 2 shows schematically the essential portion of a magnetic
head assembly of the invention;
26. FIG. 3A shows schematically a plan view of a magnetic recording
device of the invention;
27. FIG. 3B shows a cross-sectional view of the magnetic recording
device shown in FIG. 3A;
28. FIG. 4 shows schematically the essential portion of another
magnetic head assembly of the invention;
29. FIG. 5A shows schematically the essential portion of a magnetic
head of the invention;
30. FIG. 5B shows schematically the essential portion of another
magnetic head of the invention;
31. FIG. 6A shows schematically the essential portion of magnetic
write head pole structure of the invention;
32. FIG. 6B shows a cross-sectional view of the magnetic head pole
structure shown in FIG. 6A;
33. FIG. 7A shows schematically the essential portion of another
magnetic write head pole structure of the invention;
34. FIG. 7B shows a cross-sectional view of the magnetic write head
pole structure shown in FIG. 7A;
35. FIG. 8A shows schematically the essential portion of still
another magnetic write head pole structure of the invention;
36. FIG. 8B shows a cross-sectional view of the magnetic write head
pole structure shown in FIG. 8A;
37. FIG. 9 is a graph showing an effect of additive elements;
38. FIG. 10A shows schematically a plan view of a conventional
magnetic disk device;
39. FIG. 10B shows a sectional view of the conventional magnetic
disk device shown in FIG. 10A;
40. FIG. 11A shows schematically a partial sectional view of the
essential portion of a conventional magnetic head with write and
read elements;
41. FIG. 11B shows schematically the conventional magnetic head
shown in FIG. 11A; and
42. FIG. 12 shows schematically the essential portion of a
conventional magnetic recording medium.
Example 1
43. The magnetic disk of the invention is shown in FIGS. 3A and 3B.
FIG. 3A is a plan view of the device and FIG. 3B is a sectional
view of the device. In the device of the invention, a recording
medium 31 of the invention, which will be described later in detail
by referring to FIG. 1, is fixed to a rotary hub 34 and rotated by
a motor 310, and recording is performed by a magnetic head 32,
which will be described later in detail by referring to FIGS. 11A
and 11B. The magnetic head 32 is supported by a rotary actuator 33
via an arm 311 and positioned fast and in a stable manner in a
prescribed position of the rotating recording medium 31. In the
drawing, the numeral 313 denotes a suspension. As shown in FIG. 2
which illustrates the details of the suspension 313, the suspension
313 used in this device is an integrated circuit suspension in
which the wiring 21 and an insulating layer are integrally formed
on a plate spring through the use of the thin film technology so
that the inductance of the wiring 21 is not more than 15 nH. Usual
wiring of twist wires and wiring with an inductance of not less
than 15 nH, signals higher than 50 MB/s attenuate greatly. Thus,
conventional types of wiring could not been adequately put to
practical use when circuits of usual power were used. In a case
where an R/W-IC portion 314 was formed on the above integrated
circuit suspension 313, in which the thin-film wiring and
insulating layer were directly formed on the plate spring, or an
FPC for wiring, and the distance from the head was not more than 2
cm, the attenuation of signals was not practically observed and an
improvement in transfer rate of not less than tens of megabytes per
second was observed compared to a case where an R/W-IC was
integrated with a signal processing circuit and mounted on a
circuit board as conventionally. Thus, this was especially
preferable. In this example of the invention, the distance was set
at 1.5 and 1 cm. Incidentally, FIGS. 10A and 10B illustrates an
example in which four magnetic disks 31-1 to 31-4 and eight
magnetic heads 32 are mounted. However, at least one magnetic disk
and at least one magnetic head may be installed. In this example of
the present invention, 1 to 30 heads and 1 to 15 magnetic disks
were mounted on a casing 312 of magnetic disk device shown in FIG.
3.
44. The same prescribed electric circuit as conventional technology
is required for recording information, processing read signals and
inputting/outputting information. In terms of power consumption,
however, a circuit using a CMOS is advantageous in comparison with
a circuit using a Bi-CMOS and it is necessary to downsize circuitry
in order to perform recording and reading at a high rate of 50
MB/s. In all cases, therefore, it was necessary to adopt the
patterning process for not more than 0.35 .mu.m in fabricating a
part of the R/W-IC. In an actual case where a patterning process
for not less than 0.5 .mu.m was adopted, good recording could not
be performed. Incidentally, for channel LSIs for signal processing,
etc., it is necessary to reduce the circuit scale in order to
reduce power consumption and a patterning process for not more than
0.25 .mu.m was adopted. In this example, a signal processing
circuit in which waveform interference in the age of high-density
design is positively utilized was introduced and separated from the
above R/W-IC. This signal processing circuit is called MEEPRML
(Modified EEPRML), in which EEPRML (Extended Extended Partial
Response Maximum Likelihood) is enhanced and the ECC function is
also enhanced. Furthermore, in the case of perpendicular magnetic
recording, reading was performed by the PR5 signal processing
method, etc. These components were installed in the circuit board
on the cover 312, etc. The number of revolutions of the device was
10,000 rpm and the flying height was from 26 to 28 nm in all
cases.
45. The medium and magnetic head of the present invention, which
compose the magnetic recording and reading device of the present
invention, is explained below in further detail.
46. First, the medium of the present invention is explained by
referring to FIG. 1. The numeral 11 indicates a non-magnetic
substrate which is made of glass, NiP-plated Al, ceramics, Si,
plastics, etc. and formed on a disk with a diameter of, for
example, 3.5", 2.5", 1.8" and 1", a tape or a card. The numeral 12
indicates a non-magnetic underlayer which is made of Cr, Mo, W,
CrMo, CrTi, CrCo, NiCr, CoCr, Ta, TiCr, C, Ge, TiNb, etc. and
contains at least one kind of element selected from the group
consisting of Cr, Mo, W, V, Nb, Ta, Ti, Ge, Si, Co and Ni as a
primary component. The numeral 13 indicates a hard magnetic layer
which comprises a crystalline magnetic substance of CoCrPtLa,
CoCrTaCe, CoNiPtPr, CoPtNd--SiO.sub.2, FeNiCoCrPm, CoFePdTaSm,
NiTaSiEu, CoWTaGd, CoNbVTb, GdFeCoPtTa, GdTbFeCoZrRh, FeRhSiBi--N,
CoPtIrSn--CoO, etc., which crystalline magnetic substance contains
at least one metal element selected from the group consisting of
Co, Fe and Ni as a primary component, at least two elements
selected from a second group consisting of Cr, Mo, W, V, Nb, Ta,
Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and a least one kind of element
selected from a third group consisting of La, Ce, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B- This
hard magnetic material has an absolute value of normalized noise
coefficient per recording density of not more than
2.5.times.10.sup.-8 (.mu.Vrms) (inch) (.mu.m).sup.0.5/(.mu.Vpp).
The numeral 14 indicates a protective layer made of C to which N
and H are added in combination, H-added C, BN, ZrNbN, etc. The
numeral 15 indicates a lubricant of perfluoro-alkyl-polyether
having adsorptive or reactive end-groups such as OH and NH.sub.2,
an organic fatty acid, etc. Between the non-magnetic under layer 12
and the hard magnetic layer 13, there may be provided a second
non-magnetic underlayer whose composition is further adjusted and
which has a lattice constant capable of being more easily matched
to that of the magnetic film. When the above magnetic layer is
divided by a non-magnetic intermediate layer which contains at
least one element selected from the group consisting of Cr, Mo, W,
V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, C and B as a primary
component, noise decreases almost in proportion to the square root
of the total number of magnetic layers. Therefore, this is more
preferable.
47. Embodiments of medium of the present invention are explained
below in further detail. The magnetic disks of the present
invention shown in Table 1 were obtained by first forming an
underlayer on a glass disk substrate with a diameter of 3.5, 2.5,
1.8 or 1 inch, then forming a magnetic layer of single-layer,
two-layer or multilayer structure, a 10-nm thick carbon protective
film to which 10% N is added, and finally forming a 5-nm thick
lubricating film of perfluoro alkyl polyether having --OH end group
after surface treatment. The above underlayer is made of the Cr
alloys, Mo alloys, Ti alloys, W alloys, etc., which contains at
least one element selected from the group consisting of Cr, Mo, W,
V, Nb, Ta, Ti, Ge, Si, Co and Ni as a primary component. The above
magnetic layer comprises a crystalline magnetic material of
CoCrPtGd, CoCrPtTaNd, CoPtDy-SiO.sub.2, FeCoNiMoTaBi, NiFeCrPtGe,
FeNiTaIrSm, etc., which crystalline magnetic material contains at
least one metal element selected from the group consisting of Co,
Fe and Ni as a primary component, at least two elements selected
from a second group consisting of Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf,
Pd, Pt, Rh, Ir and Si, and at least one element selected from a
third group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy,
Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B.
48. The above underlayer and magnetic layer were both formed by
means of a DC magnetron sputtering device and the above protective
film was formed in an N.sub.2 gas atmosphere by the plasma-induced
reactive magnetron sputtering method. Incidentally, in this
example, parameters could be varied independently of the underlayer
and magnetic film each other and Ar pressures of from 1 to 10 m
Torr, substrate temperatures of from 100 to 300.degree. C. and
deposition rates of from 0.1 to 1 Im/s were used. In the
underlayer, Cr, Ta, Nb, V, Si and Ge or alloys such as Co60Cr40,
Mo90-Cr10, Ta90-Cr10, Ni50Cr50, Cr90--V10, Cr90--Ti10, Ti95-Cr5,
Ti--Ta15, Ti--Nb15, TiPd20, TiPtl15, etc. were used as a single
layer or two layers composed of dissimilar metal layers. Thus,
samples of different underlayer compositions were prepared. The
total film thickness of the underlayer was from 10 to 100 nm, that
of the magnetic layer was from 10 to 100 nm, and that of the
protective film was 10 nm. A multilayer medium 70 nm in thickness
was also made by way of trial by depositing ten layers of a
combination of 5-nm thick CoCr.sub.7Pt.sub.6Gd.sub.3 and 2-nm thick
Pt layers. The magnetic recording medium of the present invention
was evaluated by SEM or TEM and it was found that the magnetic
layer is predominantly composed of fine crystal grains with their
average grain sizes of not more than 12 nm and not less than 8 nm
for both longitudinal and perpendicular media.
1TABLE 1 Under Ar sputtering Temperature of Orientation layer
pressure substrate of magnetic Magnetic layer (nm) (nm) (mTorr)
(.degree. C.) layer 1 CoCr.sub.15Pt.sub.8La.sub.4(25) CrTi(40) 2
250 in-plane 2 CoMo.sub.15Pt.sub.8Ce.sub.1(25) CrTI(60) 2 250
in-plane 3 CoW.sub.19Pt.sub.4Pr.sub.2(25) CrTi(100) 2 250 in-plane
4 CoCr.sub.15Pt.sub.8Ta.sub.4Nd.sub.4(28) MoCr(10) 5 100 in-plane 5
CoCr.sub.16Pt.sub.10Ta.sub.3Pm.sub.5(28) MoCr(20) 5 150 in-plane 6
CoCr.sub.17Pt.sub.10Ta.sub.2Sm.sub.3(28) MoCr(30) 5 200 in-plane 7
CoCr.sub.13Pt.sub.8V.sub.5Eu.sub.4(35) CrV(10) 10 300 in-plane 8
CoCr.sub.16Pt.sub.12Nb.sub.2Gd.sub.6(35) Wsi(20) 10 300 in-plane 9
CoCr.sub.15Pt.sub.15V.sub.4Tb.sub.4(35) CoCr(30) 10 300 in-plane 10
NiFe.sub.10Cr.sub.10Ir.sub.4Dy.sub.4(26) NiCr(20) 1 209 in-plane 11
FeNi.sub.30Ta.sub.5Rh.sub.4Ho.sub.2(18) MoCr(30) 2 250 in-plane 12
FeCr.sub.19Pt.sub.8Er.sub.7(29) CoCr(50) 2 275 in-plane 13
CoPt.sub.20Ir.sub.4Tm.sub.1--SiO.sub.2(25) Ta(45) 1 250 in-plane 14
CoPt.sub.15Ni.sub.4Yb.sub.8--ZrO.sub.2(25) V(30) 1 181 in-plane 15
CoNi.sub.22Pt.sub.20Pd.sub.4Lu.sub.0.5-- Nb(50) 1 224 in-plane
SiO.sub.2(22) 16 CoCr.sub.23Pt.sub.10Ti.sub.5Bi.sub.4(100) TiCr(50)
2 174 perpendicular 17 CoCr.sub.23Pt.sub.10Ti.sub.5Bi.sub- .4(100)
TiCr(50) 3 160 perpendicular 18 CoCr.sub.21Pt.sub.8Hf.sub.3-
Sn.sub.4(60) TiTa(50) 4 156 perpendicular 19
CoCr.sub.22Pt.sub.8Pd.sub.3Ge.sub.15(50) CoTaZr(50) 6 140
perpendicular 20 CoCr.sub.22Pt.sub.6Rh.sub.2B.sub.0.1(40)
CoNbZr(50) 6 106 perpendicular 21
CoCr.sub.22Pt.sub.6si.sub.2Sm.sub.4(40) TiPd(50) 6 191
perpendicular 22 CoCr.sub.7Pt.sub.6Gd.sub.3/Pt(70) SiN(50) 5 151
perpendicular
49.
50. Next, the magnetic head of the present invention is explained
by referring to FIG. 2 and FIG. 11A. A magnetic pole 117 of
43Ni--57Fe with a saturation magnetic flux density of 1.5 T and a
resistivity of 50 .mu..OMEGA.cm and another magnetic pole 118 of
Ni80Fe20 with a saturation magnetic flux density of 1.0 T and a
resistivity of 28 .mu..OMEGA.cm were formed by the frame plating
method. Cu wiring of 2 layers and 15 turns was formed within a
magnetic core length l.sub.1 of 35 .mu.m. The length of a record
gap 111 was 0.32 .mu.m (material for the gap: Al.sub.2O.sub.3).
Furthermore, the read element was fabricated as follows. A
magnetically free NiFe/Co film (6 nm), a Cu film (2.5 nm), a
magnetically fixed layer CoFe film (5 nm) and a CrMnPt film (25 nm)
were first formed one after another and a rectangular pattern was
obtained. After that, a permanent magnet of Co80--Ni15--Pt5 (15
nm)/Cr (12 nm) and an electrode film of Ta (120 mm) were arranged
on both ends of the pattern and a giant magnetoresistive element
with a track width of 0.9 .mu.m, which is determined by the gap
distance between the electrodes, was provided on a 2-.mu.m thick
plated shielding film of Ni80-Fe20 by the i-line lithography
technology, thereby giving this structure to the read element
(shield gap: 0.3 .mu.m, material for the gap: Al.sub.2O.sub.3). The
magnetic head element provided with this read element was formed on
a slider made of Al.sub.2O.sub.3--TiC with a size of
1.0.times.0.8.times.0.2 mm.sup.3. Incidentally, the recording track
width was trimmed to 1.1 .mu.m from the floating surface side by
the FIB (Focused Ion Beam) fabrication technology and a shaped rail
structure was fabricated to the floating surface of the head. In
addition, to improve the anti-adhesive property minute projections
were provided at three points of the floating surface and a C/Si
protective film with a total thickness of 3 nm was formed on the
floating surface. As shown in FIG. 3, this head, along with an
RW-IC 314 for which the scaledown process for 0.35 .mu.m in this
example was adopted, was fixed with an adhesive to an integrated
circuit suspension 313 of the present invention on which a
conductive line pattern through an insulating film were formed by
the thin film fabrication process. A magnetic head assembly was
thus obtained. As a result of the foregoing, in the integrated
circuit suspension of the present invention for a disk with a
diameter of 3.5, 2.5, 1.8 or 1 inch, the total inductance of the
head assembly measured from R/W IC terminals at 1 OMHz was 65, 63,
61 and 57 nH, respectively, not more than 65 nH.
51. Incidentally, heads with a magnetic core length 1.sub.1 of 25,
30 and 40 .mu.m were also made by changing the number of turns to
9, 11 and 13, respectively. When the magnetic core length was 40
.mu.m, in the integrated circuit suspension of the present
invention for a disk with a diameter of 3.5, 2.5, 1.8 or 1 inch,
the total inductance was as large as 75, 73, 71 and 68 nH,
respectively. In these cases, the overwrite characteristic at 50
MB/s was as low as 20 dB, sufficiently sharp recording could not be
performed, and noise was very large. Thus, these heads could not be
put to practical use. From the above, it became apparent that it is
necessary that the magnetic core length be not more than 35 .mu.m
and that the total inductance be not more than 65 nH. Table 1 shows
only cases in which goods results were obtained with an overwrite
characteristic of not less than 30 dB. Furthermore, when the
characteristic was evaluated on a tunneling magnetic head with a
read track width of 0.85 .mu.m, made by the technology stated in
JP-A-02-148643 and JP-A--02-218904, quite the same result was
obtained. With a conventional MR head having the same track width
for comparison, however, even in a case where the condition of the
device was evaluated through the use of a signal processing circuit
of the EEPRML type by the lithography process of 0.25 .mu.m,
sufficient read output and error rates could not be obtained. Thus,
this conventional MR head could not bear the evaluation.
52. The device characteristics of the present invention are
described blow. A signal processing circuit of the EEPRML type by
the lithography process of 0.25 .mu.m was used. In order to perform
high-density, high data rate recording with high quality and a high
signal-to-noise ratio for the characteristic in each record track
position, it is necessary to ensure a strong and sharp recording
magnetic field at a high frequency and, at the same time, it is
necessary to reduce the irregularity of the saw tooth magnetic
domains at record bit boundaries by reducing the crystalline
grainsize in the medium and also reducing the exchange interaction
among magnetic crystalline grains, to reduce the noise at bit
boundaries that increases in proportion to recording density, and
to ensure an appropriate response to a high-frequency magnetic
field by optimizing the damping of magnetization during recording.
For comparison, media were made without the addition of only the
third group of elements so that these media correspond to those
given in Table 1. On the media of these comparative examples, when
recording was performed at a transfer rate of not less than 20
MB/s, the absolute value of normalized noise coefficient per
recording density increased abruptly at 5 Gb/in.sup.2 even when the
above-mentioned head and R/W-IC were used. When recording was
performed at 50 MB/s, the absolute value of normalized noise
coefficient per recording density reached large values of from 10
to 30.times.10.sup.-8 (.mu.Vrms) (inch) (.mu.m).sup.0.5/(.mu.Vpp)
and the bit error rate of the device was worse than 10.sup.-5.
Thus, these medium could not be used for practical use. In
contrast, all the media of the embodiments shown in Table 1 had an
absolute value of normalized noise coefficient per recording
density of from 1 to 2.5.times.10.sup.-8 (.mu.Vrms) (inch)
(.mu.m).sup.0.5/(.mu.Vpp), which are not more than
2.5.times.10.sup.8 (.mu.Vrms) (inch) (.mu.m) ).sup.0.5/(.mu.Vpp),
and the bit error rate was better than 10.sup.-9 even under the
conditions of both 5 Gb/in.sup.2 and 50 MB/s. Thus, it became
apparent that these media of this example were especially
preferable.
53. For the effect of the elements of third group to a medium,
cases with additives of from 0.1 to 15% were described in this
example. However, as is apparent from FIG. 9 which shows cases with
varied La contents of 0.01, 0.1, 0.5, 1, 2, 10, 15, and 20 at%
under the conditions of #1 of Example 1, the signal-to-noise ratio
in recording at 50 MB/s improved remarkably. The effect is
sufficient when the quantity of additives is 1 at%. The output and
signal-to-noise ratio decreased remarkably when the quantity of
additives was not less than 15 at% and, therefore, this was not
preferable. Furthermore, the effect was especially remarkable when
rare earth elements were added.
54. A medium of another embodiment was prepared under the same
conditions as those for the above first embodiment of Example 1 by
dividing the magnetic layer into two layers by a non-magnetic
intermediate layer, which contains as a main element at least one
selected from the group consisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf,
Ti, Ge, Si, Co, Ni, C and B singly or Cr--Ti10, Mo--Cr10, W--Si5,
Ta--Si5, Nb--Zr10, Ta--Cr5, Zr--Hf10, Hf--Ti5, Ti--Si10, Ge--Pt5,
Si--Ru11, Co--Cr30, C--N10, B--N10, etc. However, noise reduced to
approximately 70% and the device operated adequately even under the
conditions of both 7 Gb/in.sup.2 and 50 MB/s. Thus, the effect was
more remarkable. It is needless to say that the above effect does
not depend on the diameter of a disk or forms of medium such as a
disk, tape and card.
Example 2:
55. Another example of the present invention is explained by
referring to the conceptual drawing of a magnetic head assembly
shown in FIG. 4. For a magnetic head 42, first as recording
elements, 40Ni--55Fe--5Cr with a saturation magnetic flux density
of 1.4 T and a resistivity of 60 .mu..OMEGA.cm was used as the
material for a magnetic pole 117 with a track width of 0.6 .mu.m
and another magnetic pole 118 was formed from CoTaZr with a
resistivity of 120 .mu..OMEGA.cm in FIG. 11A. Track width
fabrication was performed by trimming on the basis of the FIB
technology as with Example 1. A record gap length of 0.25 .mu.m
(material for the gap: Al.sub.2O.sub.3-3%SiO.sub.2) was selected,
the magnetic core length 1.sub.1 was 30 .mu.m, and an Al coil 116
of 2 layers and 12 turns was used. Furthermore, the read element
was fabricated as follows. A magnetically free NiFe/Co film (6 nm),
a CuNi film (2.5 nm), a magnetically fixed layer of CoFe/Ru/CoFe
film (6 nm) and an MnIr film (15 nm) were first formed one after
another and a rectangular pattern was fabricated. After that, a
permanent magnet of Co75--Cr15--Pt12 (10 nm)/CrTi (5 nm) and an
electrode film of Nb (100 mm) were arranged on both ends of the
pattern and the above giant magnetoresistive element with a track
width of 0.5 .mu.m, which is determined by the distance between the
electrodes, was provided on a 2.5-.mu.m thick plated shielding
layer of Ni80--Fe20 through an 0.45 .mu.m thick shield gap 110 in
FIG. llA of Al.sub.2O.sub.3, thereby giving this structure to the
read element (total shield gap: 0.20 .mu.m, material for the gap:
ZrO.sub.2). A magnetic head 42 was obtained by forming this element
on a slider made of Al.sub.2O.sub.3--TiC with a size of
1.0.times.0.8.times.0.2 mm.sup.3. The magnetic head assembly was
obtained by mounting this head on an integrated circuit suspension
of the present invention of FIG. 4 in which lead pattern through an
insulating layer were formed by the thin film fabrication
process.
56. In FIG. 4, with the assistance of a fine adjustment portion 43
of electromagnetic drive, etc. capable of position corrections of
about 10 .mu.m at a high rate, a suspension 44 has the function of
positioning a magnetic head 42 in the prescribed position of the
recording medium at a high speed in collaboration with the rough
movement function of a rotary air actuator 45. For this reason, in
Example 2, the R/W-IC of this example fabricated by the processes
for 0.35 and 0.25 .mu.m line widths was mounted on a wiring FPC
(Flexible Printed Circuit) installed adjacent to an integrated
circuit suspension in which lead pattern was formed by the thin
film process, and its distance from the head was 3, 2, 1.5, 1 and
0.7 cm. Incidentally, a signal processing LSI of the EEPRML by the
scaledown process for 0.25 .mu.m was used. Incidentally, the fine
adjustment portion 43 is not limited to a fine movement means of
the electromagnetic force drive type and may be a fine movement
means of the piezoelectric force drive type, magnetostrictive force
drive type, etc. As a result of a comparison and examination, it
was found that the type in which a multilayer piezoelectric device
is used has the least adverse effect on power consumption and the
read element of GMR or MR. However, the other types also met
required functions. Another disk device of the present invention
was obtained by mounting this head assembly on a magnetic disk
device of the present invention shown in FIGS. 3A and 3B and by
using the media of 2.5" and 1.8' diameters shown in Table 1 and the
same circuit as in Example 1. In Example 2, combinations of 1 to 10
media and 1 to 20 heads were used. Incidentally, a slider of shaped
rail structure with three minute projections was used and a 3-nm
thick protective film of C--N--H was provided on the bearing
surface. However, during the evaluation, the flying height of the
magnetic head was 25 nm and the number of revolutions was 15,000
and 25,000 rpm.
57. In all the combinations, the device operated adequately in a
condition better than a bit error rate of 10.sup.-9 under the
conditions of 10 Gb/in.sup.2 and 50 MB/s. Thus, this effect was
more remarkable. At 20,000 rpm, recording was severer and the
device operated in a condition better than a bit error rate of
10.sup.-10 when the R/W-IC of the present invention based on the
process for a line width of 0.25 .mu.m was used. This was
especially preferable. Incidentally, for the distance between the
R/W-IC of the present invention and the head of the present
invention, the data transfer rate could be increased to 50, 54, 54,
54 and 55 MB/S with decreasing distance to 3, 2, 1.5, 1 and 0.7 cm,
respectively. Distances of not more than 2 cm were especially
effective. It is needless to say that this effect does not depend
on the diameter of a disk or forms of medium such as a disk, tape
and card.
Example 3:
58. A third example of the present invention is described below by
referring to FIGS. 5A and 5B, FIGS. 8A and 8B and FIGS. 3A and
3B.
59. As shown in FIGS. 5A and 5B, a laser chip 52, 52' of about 0.3
mm square was mounted on a position-correcting mount 51, 51' of the
piezoelectric force type, electromagnetic force type or
magnetostrictive force type. The laser chip thus mounted on the
position-correcting mount was then mounted on a head slider 50, 50'
as shown in FIGS. 5A and 5B to permit adjustments so that a
recording and reading element portion 53, 53' and a laser beam
position 54, 54' are located almost on the same record track 55,
55'. An Al.sub.2O.sub.3--TiC slider of shaped rail structure with a
size of 0.7.times.0.2 mm.sup.3 (FIG. 5A), provided with three
minute projections, was used and a 3-nm thick protective film of
C--N was provided on the floating surface. The volume including the
laser chip (FIG. 5B) was 1.0.times.0.9.times.0.2 mm.sup.3, and the
distance over which corrections are possible was 20 .mu.m maximum.
Although the correction mechanism is not always necessary, the
absence of this mechanism was not much preferable because of a low
margin for reproducibility. Incidentally, the laser wavelength was
830, 780, 650 and 630 nm and the power was from 5 to 50 mW. To
prevent degradation, the end faces of the laser were provided with
protective films. The shape of a laser beam was almost oval as
indicated by 54, 54'. As shown in this figure, an examination was
made as to two cases. In one case, the direction of the minor axis
of about 1 .mu.m was almost parallel to the record track 55, 55'
and in the other case, the direction of the minor axis was
perpendicular to the record track 55, 55'. The flying height was 10
nm.
60. Incidentally, the recording element shown in FIGS. 6A and 6B,
FIGS. 7A and 7B and FIGS. 8A and 8B was first used corresponding to
the recording element 53, 53'. In the embodiment shown in FIGS. 6A
and 6B, a 36Ni--62Fe--2Nb film with a resistivity of 75
.mu..OMEGA.cm and a film thickness of 1.8 .mu.m was formed as 62
and 64 and a 45Ni--55Fe film with a resistivity of 45 .mu..OMEGA.cm
and a film thickness of 1.8 .mu.m was formed as 61 and 63. As shown
in FIG. 6A, a track width T.sub.ww of 0.53 .mu.m was obtained in
the wafer state by performing trimming through the use of ion
milling, the RIE method, etc. Furthermore, a magnetic core length
1.sub.1 of 35 .mu.m, a magnetic pole length 1.sub.2 of 50, 55, 60
or 65 .mu.m, a number of turns of Cu coil of 15, and a recording
gap length Gl of 0.19 .mu.m (material for the gap:
Al.sub.2O.sub.3--5%SiO.sub- .2) were obtained.
61. In another embodiment shown in FIGS. 7A and 7B, an
80Co--10Ni--10Fe--1P film with a resistivity of 20 .mu..OMEGA.cm
and a film thickness of 0.7 .mu.m was formed as 72 and 74 and a
75Co--10Ni--10Fe--5P film with a resistivity of 65 .mu..OMEGA.cm
and a film thickness of 1.5 .mu.m was formed as 71 and 73. As shown
in FIG. 7A, a track width T.sub.ww of 0.47 .mu.m was obtained in
the wafer state by performing fabrication and, furthermore, a
magnetic core length 1.sub.1 of 33 .mu.m, a magnetic pole length
1.sub.2 of 45, 50, 55, 60 or 65 .mu.m, a number of turns of Cu coil
116 of 15, and a record gap length Gl of 0.18 .mu.m (material for
the gap: Al.sub.2O.sub.3--5%SiO.sub.2) were obtained.
62. In a further embodiment shown in FIGS. 8A and 8B, a multilayer
film, obtained by alternately depositing an 90Fe--5Al--5Si film
with a resistivity of 20 .mu..OMEGA.cm and a film thickness of 0.1
.mu.m and a 10-nm thick ZrO.sub.2 layer to form a total of ten
layers, was formed as 82 and a 75Co--15Ta--10Zr film with a
resistivity of 100 .mu..OMEGA.cm and a film thickness of 1.5 .mu.m
was formed as 118. As shown in FIG. 8A, a track width T.sub.ww of
0.5 .mu.m was obtained in the wafer state by performing trimming by
the FIB method and, furthermore, a 44Ni--56Fe film with a
resistivity of 45 .mu..OMEGA.cm and a film thickness of 1.9 .mu.m
was formed with an end width of 0.7 .mu.m. The magnetic core length
1.sub.1 was 33 .mu.m, the magnetic pole length 1.sub.2 was 40, 50,
55, 60 or 65 .mu.m, the number of turns of Cu coil 116 was 11, and
the record gap length Gl was 0.20 .mu.m (material for the gap:
A1.sub.2O.sub.3--7%SiO.sub.2). Incidentally, still further
embodiments with the same magnetic core length, but with different
magnetic pole lengths of 55, 60 and 65 .mu.m were also fabricated
in addition to the above embodiments.
63. In all of these embodiments, the read element was fabricated as
follows. A magnetically free NiFe/CoFe film (5 nm), a CuNi film
(2.5 nm), a magnetically fixed layer of CoFe/Ru/CoFe film (5 nm)
and an MnIr (13 nm) film were formed one after another and a
rectangular pattern was obtained. After that, a permanent magnet of
Co75--Ni15--Pt10--5%HfO.sub.2 (12 nm) and an electrode film of
Nb--Tl (90 mm) were arranged on both ends of the pattern and a
giant magnetoresistive element with a track width of 0.41 .mu.m,
which is determined by the spacing between electrodes, was provided
on a 2.1-.mu.m thick plated shielding film of Ni80--Fe20 through
the gap, thereby giving this structure to the read element (total
shield gap: 0.8 .mu.m, material for the gap: Ta.sub.2O.sub.5). The
read portion thus fabricated was used as the magnetic head element
of the present invention. In this example, an RW-IC fabricated by
the scaledown process for 0.25 .mu.m was mounted on the integrated
circuit suspension that supports the above head. A signal
processing LSI separately installed was of the EEPRM type formed by
the scaledown processes for 0.25 and 0.2 .mu.m.
64. The following media of the same structure as those shown in
FIG. 1 were newly fabricated in addition to the media shown in
Table 1. An amorphous magnetic material, which contains at least
one metal element selected from the group consisting of Co, Fe and
Ni as a primary component, at least two elements selected from a
second group consisting of Cr, Mo, w, V, Nb, Ta, Ti, Zr, Hf, Pd,
Pt, Rh, Ir and Si, and a least one element selected from a third
group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er,
Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B, was formed on a non-magnetic
substrate of Si with a diameter of 3.5, 2.5, 1.8, 1 inch, etc. The
numeral 14 indicates a protective film made of N-added C, H-added
C, BN, ZrNbN, AlN, SiAlOH, etc. The numeral 15 indicates a
lubricant of perfluoro-alkyl-polyether having adsorptive or
reactive end groups such as OH and NH.sub.2, an organic fatty acid,
etc. Between the non-magnetic underlayer 12 and the hard magnetic
layer 13, there may be provided a second non-magnetic underlayer
whose composition is further adjusted. When the above magnetic
layer is divided by a non-magnetic intermediate layer, which
contains as a main element at least one selected from the group
consisting of Cr, Mo, V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, Al,
Zn, C and B singly or Cr--Ti10, Mo--Cr10, W--Si5, Ta--Si5,
Nb--Zr10, Ta--Cr5, Zr--Hf10, Hf--Ti5, Ti--Si10, Ge--Pt5, Si--Rull,
Co--Cr30, C--N10, B--N10, etc., noise decreases almost in
proportion to the square root of the total number of magnetic.
Therefore, this is more preferable.
65. This example is explained below in further detail. A magnetic
disk was fabricated by forming a non-magnetic underlayer of SiN, Cr
alloy, etc. on an Si disk with a diameter of 1.8" and then further
depositing one after another an amorphous magnetic layer of TbFeCo,
DyFeCo, NdTbFeCo, TbFeCoNb, TbFeCoPt, etc., an 8-nm thick
protective film of carbon to which 15% N is added, and a 5-nm thick
lubricating film of perfluoro-alkyl-polyether having end groups of
--OH.
66. Both the underlayer of SiN, Cr alloy, etc. and the magnetic
layer were formed by means of an RF magnetron sputtering device
using Ar gas and the protective film was further formed in an
N.sub.2 gas atmosphere by the plasma-induced reactive magnetron
sputtering method. On that occasion, the Ar pressures was from 0.5
to 10 m Torr, the substrate temperatures was from 50 to 200.degree.
C., and the deposition rate was about 3 nm/s. In the underlayer,
Al.sub.2O.sub.3 and Cr--Ti were used as a single layer or two
layers composed of dissimilar underlayers in addition to SiN and
Cr. Thus, samples of different underlayer compositions were
prepared. The total film thickness of the underlayer was from 10 to
200 nm, that of the amorphous magnetic layer of TbFeCo, DyFeCo,
NdTbFeCo, TbFeCoNb, TbFeCoPt, TbFeCoBi, etc. was from 20 to 750 nm,
and that of the protective film was 8 nm. Compositions with a
higher Fe concentration than usual compositions used in
magneto-optic disks permit great saturation magnetization and allow
the film thickness of a medium to be relatively reduced. Therefore,
this was favorable in terms of magnetic recording. Magnetic disks
of the present invention made by way of trial in Example 3 are
shown in Table 2.
2TABLE 2 Under Ar sputtering Temperature of Orientation layer
pressure substrate of magnetic Magnetic layer (nm) (nm) (mTorr)
(.degree. C.) layer 1 CoTb.sub.10Zr.sub.3Pt.sub.15(200) CrTi(40)
0.2 200 in-plane 2 FeCo.sub.10Tb.sub.15Pt.sub.5Cr.sub.2(270)
CrTa(60) 0.2 180 perpendicular 3
FeCo.sub.5Tb.sub.20Si.sub.5Pd.sub.2(350) Al.sub.2O.sub.3(100) 0.5
150 perpendicular 4 FeCo.sub.5Tb.sub.7Bi.sub.5Ta.sub.2Cr.sub.1-
(20) CrV(30) 0.5 100 perpendicular 5
FeCo.sub.10Tb.sub.15Nb.sub.5Mo- .sub.2(270) Cr(20) 1.0 150
perpendicular 6 FeCo.sub.15Dy.sub.15Bi.s- ub.5V.sub.2Ti.sub.2(450)
ZnS(30) 1.0 200 perpendicular 7
FeCo.sub.10Tb.sub.30Ge.sub.5Zr.sub.2Ir.sub.2(570) Wti(10) 2.0 50
perpendicular 8 FeCo.sub.10Nd.sub.15Pt.sub.2W.sub.2(370) MoSi(20)
2.0 200 perpendicular 9 FeCo.sub.5Dy.sub.10Lo.sub.5Rh.sub.2Hf.sub.-
2(45) NiCr(30) 5.0 50 perpendicular 10
FeCo.sub.13Tb.sub.26Ce.sub.5- Pt.sub.2Tr.sub.2(350) CoCr(20) 5.0
100 perpendicular 11 FeCo.sub.10Tb.sub.15Pt.sub.2Ta.sub.2(270)
TaCr(30) 0.2 150 perpendicular 12 FeCo.sub.7Dy.sub.25Nd.sub.5(350)
MoCr(90) 0.2 175 perpendicular 13
FeCo.sub.36Tb.sub.16Nd.sub.13Pt.sub.2V.sub.3(650) TaCr(65) 0.5 150
perpendicular 14 FeCo.sub.42Nd.sub.20Pr.sub.5Pt.sub.2Ti.sub.2(-
750) V(40) 0.5 181 perpendicular 15
FeCo.sub.16Tb.sub.26Eu.sub.5Pt.- sub.4Pd.sub.2(750) Nb(40) 1.0 124
perpendicular 16 FeCo.sub.13Tb.sub.23Nb.sub.1W.sub.2(650) TiCr(50)
1.0 54 perpendicular 17
FeCo.sub.10Tb.sub.20Pm.sub.3Si.sub.2W.sub.2(590) WCr(50) 2.0 165
perpendicular 18 FeCo.sub.15Dy.sub.15Gd.sub.5Ir.sub.2W.sub.2(580)
TiTa(60) 2.0 65 perpendicular 19 FeCo.sub.15Tb.sub.22Rh.sub.2Zr.su-
b.2(570) TiV(50) 5.0 145 perpendicular 20
FeCo.sub.10Nd.sub.15Pd.su- b.2Si.sub.2(690) TiPt(50) 5.0 116
perpendicular 21 FeCo.sub.12Tb.sub.28Iio.sub.5Ir.sub.2Ti.sub.2(680)
TiPd(50) 10 195 perpendicular 22
FeCo.sub.10Tb.sub.22Er.sub.5Zr.sub.2V.sub.2(530) TiNb(60) 10 121
perpendicular 23 FeCo.sub.10Tb.sub.22Tm.sub.5Nb.su-
b.2Mo.sub.2(570) SiN(60) 10 101 perpendicular 24
FeCo.sub.10Tb.sub.22Yb.sub.5Cr.sub.2W.sub.2(480) C(50) 1.0 95
perpendicular 25 FeCo.sub.10Tb.sub.22Lu.sub.5(500) Ge(50) 1.0 81
perpendicular
67.
68. In all of the media of this example, the magnetic films are
made of amorphous materials with an in-plane or a perpendicular
anisotropy. Especially, in perpendicular media, the noise
coefficient is generally negative. In media with a coercive
squareness of not less than 0.95, noise was especially low and this
was preferable. In all cases, the absolute value of normalized
noise coefficient per recording density was not more than
2.5.times.10.sup.-8 (.mu.Vrms) (inch) (.mu.m).sup.0.5/(.mu.Vpp).
Under the same conditions as with the above third example in Table
2, media of another embodiment were fabricated by dividing the
magnetic layer into two layers by a non-magnetic intermediate
layer, which is made of Cr, Mo, W, V, Nb, Ta, Zr, Hf, Ti, Ge, Si,
Co, Ni, C or B singly or Cr--Ti10, Mo--Cr10, W--Si5, Ta--Si5,
Nb--Zr10, Ta--Cr5, Zr--Hf10, Hf--Ti5, Ti--Si10, Ge--Pt5, Si--Rull,
Co--Cr30, C--N10, B--N10, S--N50, etc. In all these media, noise
decreased to the levels of from 65 to 75%. This was especially
preferable.
69. To fabricate a magnetic disk device, 10 media shown in Table 1
or Table 2 were mounted as 31 and 20 heads of each of the above
embodiments were mounted as shown in FIGS. 3A and 3B. Recording was
performed by magnetic fields from the magnetic heads while
controlling the coercive force of media by the local heating
effected by means of a laser during information recording. The
number of revolutions was from 20,000 to 30,000 rpm and temperature
rises in the recording positions of media by local heating were
optimally controlled in the range of about 50.degree. C. to
300.degree. C. Under this method, recording conditions are
susceptible to fluctuations in external temperature. Therefore, it
was desired to optimize laser power by performing trial writing in
the initial stage of recording and at prescribed intervals of time
after operation.
70. In all the media, when the major axis of laser almost coincided
with the track direction, interference with adjoining tracks was
small and the best characteristics were obtained. Even in a case
where the minor axis coincided with the track direction, however,
high densities about twice the density in conventional technology
could be realized. More specifically, areal densities of not less
than 7 Gb/in.sup.2 could be achieved at 50 MB/s for the media of
the embodiments shown in Table 1 and areal densities of not less
than 15 Gb/in.sup.2 could be achieved at 50 MB/s similarly for the
media of the embodiments shown in Table 2. In a device provided
with the above media having a magnetic layer divided into two
layers, recording density could be improved by about 20%. This was
especially preferable. Incidentally, a read signal processing LSI
fabricated by the process for 0.2 .mu.m was about 30% favorable in
terms of power consumption and processing speed.
Example 4:
71. The heads of Example 3 were also adopted as the magnetic heads
of Example 1 and Example 2 and evaluated. In all of these heads of
Example 3, operation of the device at areal densities of not less
than 7 Gb/in.sup.2 and data transfer rates of not less than 60 MB/s
were verified and characteristics equal to or better than those
obtained in Example 1 and Example 2 were obtained. This was
especially preferable in terms of data transfer rate. When the
magnetic pole length was 55, 60, and 65 .mu.m, recording and
reading were possible at a data transfer rate of from 60 to 65
MB/s. However, when the magnetic pole length was not more than 50
.mu.m, data transfer rate of from 66 to 70 MB/s was possible. This
was especially preferable. It was ascertained by a computer
simulation that it is important to reduce not only the magnetic
core length l.sub.1, but also the magnetic pole length l.sub.1
because eddy currents are generated in the rear part of a magnetic
pole. The R/W-IC portion was separated from the signal processing
portion and formed by the scaledown process for not less than 0.35
.mu.m. After that, this R/W-IC portion was mounted on the
integrated circuit suspension of the present invention in which
thin-film lead layer and an insulating layer are formed directly on
a plate spring by the thin film process, or on a wiring FPC, and
the distance from the head was set at not more than 1 cm. In this
case, degradation of signals was not practically observed and an
improvement in data transfer rate of not less than 50 MB/s was
observed compared to a case in which an R/W-IC was integrated with
a signal processing circuit and installed on a circuit board as
conventionally. This was especially preferable.
72. The above Examples 1 to 4 represent typical inventions
disclosed in the present invention and examples that can be easily
analogized by those skilled in the art also included in the scope
of the present invention. Similar effects are obtained from the RF
magnetron sputtering method, ECR sputtering method and helicon
sputtering method, for example. Furthermore, similar effects are
obtained form the oblique-evaporation method in an oxygen
atmosphere and the ionized cluster beam method and also by changing
the incidence position corresponding to each radius of a disk. It
is needless to say that similar effects are obtained by installing
a Peltier-effect element in the head and performing heating.
Furthermore, the magnetic recording medium, head and device
disclosed in this invention enable magnetic recording and reading
in high data transfer rate at not less than 50 MB/s to be performed
at a recording density of not less than 5 Gb/in.sup.2. Therefore,
high data transfer rate and large-capacity magnetic recording and
reading devices in which magnetic tapes, magnetic cards,
magneto-optic disks, etc., are used as the magnetic recording media
of the present invention, are also included in the scope of the
present invention.
73. As mentioned above, the use of the magnetic recording medium
and magnetic recording and reading device of the present invention,
for the first time, enables high data transfer rate and
large-capacity recording and reading to be performed. As a result,
magnetic recording and reading devices with very strong product
competitiveness can be realized.
* * * * *