JPS63291211A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obviate deterioration in the good magnetic characteristics possessed by a thin magnetic Co-Ni alloy film and to improve S/N by adding at least one kind among Zr, Ti and Hf and at least one kind among Al, Mo and W to Co and Ni. CONSTITUTION:Ni is incorporated into the thin magnetic Co-Ni alloy film at >=34at.% and <=55at.% content of Co and at least Al or Mo or W is incorporated therein at >=3.5at.% and <=30at.% of the total content of Co and Ni. At least one kind among Zr, Ti and Hf are incorporated at >=2at.% and <=15at.% into the magnetic alloy. At least one intermediate layers consisting of any one kind among Cr, Mo and W or alloys essentially consisting thereof are formed at >=100Angstrom and <=500Angstrom film thickness between the magnetic layer and nonmagnetic substrate. The magnetic recording medium having particularly high output and excellent recording and reproducing characteristics is thereby obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording medium for use in magnetic disk drives, etc., and is particularly suitable for high-density recording and has excellent reliability such as corrosion resistance and sliding resistance. Regarding the medium.

[Conventional technology]

Conventionally, as a magnetic recording medium for high-density recording,
As shown in No. 33523, a medium using a metal magnetic core thin film has been proposed. Generally, methods for forming the medium include vapor deposition and sputtering.

There are plating methods, ion beam sputtering methods, etc.

Recently, the demand for metal magnetic thin films has been increasing, and in particular, in order to improve magnetic properties, abrasion resistance, and corrosion resistance, Japanese Patent Application Laid-Open No. 57-183004,
M o y in magnetic metal as in the -170504 publication.
Ta? Proposals have been made to add a third element such as W.

[Problem that the invention seeks to solve]

However, most of these inventions relate to magnetic recording tapes using vapor deposition methods, ion blating methods, etc., and have not yet reached the point where they meet stricter specifications regarding recording and reproducing characteristics and reliability, such as computer hard disks.

An object of the present invention is to provide a Co-based alloy magnetic recording system that has good recording and reproducing characteristics with low noise and high S/N ratio while substantially maintaining the improved corrosion resistance and wear resistance of metal magnetic thin films. The goal is to provide a medium.

[Means for solving problems]

IVa, Va, VIa, group 4 of the periodic table. Co −
According to research conducted by the present inventors, who have intensively investigated the recording/reproducing characteristics, corrosion resistance, etc. of a magnetic film doped with Ni and formed by sputtering, etc., in order to reduce media noise and improve recording/reproducing characteristics, , the Ni content is 34 at% with respect to Co.
At least 55 at% or less, and furthermore, 3.5 at% or more and 3Q at% or less, more preferably 4 at% or more and 11 at% or less of AQ, Mo, or W based on the total amount of Co and Ni is added to at least Go-Ni based magnetic alloy. It has been found that inclusion in thin films is extremely effective.

Furthermore, in order to improve corrosion resistance, 2at% or more, 15at%
% or less of at least one of Zr, Ti, and Hf in the magnetic alloy.

Furthermore, at least one intermediate layer of any one of Cr, Mo, W, or alloys containing these as main components is provided between the magnetic layer and the nonmagnetic substrate with a thickness of 100 Å or more and 5000 Å or less.
By forming layers, it is possible to provide a magnetic recording medium with particularly high output and excellent recording and reproducing characteristics.

[Effect]

The above invention is based on the following functions. First, by sputtering method, C/(Cot-xNix)1-YMOY/C
A medium was prepared under the following conditions. 20μ on an AQ alloy substrate with an outer diameter of 130mΦ, an inner diameter of 40naΦ, and a thickness of 1.9m.
After forming a non-magnetic 12 wt% P-Ni plating layer of m, the surface was mirror-polished to a center line average surface roughness of 3 nm, and a N1-P film thickness of 15 μm was formed on the substrate. R
The substrate temperature was 150°C and the Ar gas pressure was 1 using F sputtering equipment.
5 mTorr.

After forming a Cr thin film with a thickness of 2500 nm at an RF input power of 2 W/ai to form a magnetic control layer, a Cr thin film with a thickness of 600 nm (C0l-XN ix) 1-YMOY (XmO,
14゜0.2, 0.3, 0.34, 0.4, 0.5, 0
．． 55,0.6, Y =0.02,0,035°0.0
6,0.08,0.11,0.15,0.2,0.25
, 0.3) A magnetic layer was formed. Furthermore, a carbon film with a thickness of 400 mm was formed using a CttDC magnetron sputtering device at a substrate temperature of 150°C, an Ar gas pressure of 10 m Torr, and an input power of 6 W/d.
1-YM OY/Cr disk. Figure 2 shows the dependence of the coercive force Hc on the Ni composition ratio X of this disk with a Mo composition y of 0.04.
% to 55 at%, the coercive force Hc is as large as 7500 e or more. The coercive force was highest when the Ni composition ratio X was 40 at % or more and 50 at % or less, and the reproduction output was also large in these composition ranges. This Ni composition dependence was true regardless of the MO concentration. Here, when a Co-Ni-Mo magnetic film is formed on a substrate without intervening Cr, the coercive force He is as small as 1000 degrees or less using the normal sputtering method, but a Co-based magnetic film is formed through Cr of 100 Å or more. By doing so, Ha becomes 4000e or more, which is suitable for high-density recording. This is because the crystal consistency between Cr and the Co-Ni-Mo alloy is high, and by providing a Cr underlayer, the crystal anisotropy axis (C axis) of Co-Ni-Mo has a large in-plane component. This is because it grows epitaxially. Here, if Cr of 5000 Å or more is provided, the surface roughness will increase and the flying properties of the magnetic head will deteriorate, which is undesirable.Furthermore, as shown in FIG.
From this figure, which shows the relationship between the coercive force He and the Mo composition of a medium with a concentration of 4.5%, it can be seen that H8 is high when the MO content is 3.5 to 30at%. The dependence of Hc on the Mo composition was the same regardless of the Ni composition. By the way, as the 1Mo composition increases, Ms rapidly decreases, so the Mo composition is 15at.
% or less, more preferably 11 at% or less. On the other hand, Co-N
When an i-Mo magnetic film is directly formed on a substrate by an oblique evaporation method, M
It is known that adding more than about 5 wt % (3 at %) of o actually reduces He. In addition, when directly forming a magnetic recording medium made of a Go-Ni-Mo alloy by a sputtering method, Japanese Patent Laid-Open No. 61-224
125, directly in pure Ar gas,
When formed by sputtering, Ha is small and is not suitable for magnetic recording media, but it is known that coercive force can be increased by sputtering in Ar gas containing N2 followed by heat treatment, and a highly corrosion-resistant medium can be obtained. ing. However, according to the research of the present inventors, G o -Mo, Co
When a -N i -Mo magnetic layer is formed, Hc is as high as about 5000 e or more, as shown in FIG. 4, regardless of the Mo composition.

Furthermore, when the recording and reproducing characteristics of the aqueous medium were evaluated, it became clear that the medium noise decreased with the amount of Mo added.

This is because the Hc and noise characteristics of the magnetic film are determined by the orientation and crystallinity of the Cr underlayer and the orientation and crystallinity of the magnetic film epitaxially grown thereon. Furthermore, regarding corrosion resistance, as described in JP-A-57-170504 and JP-A-61-224125, Co
-Ni-M.

It is also known that when a magnetic layer is formed, corrosion resistance improves as the amount of Mo added increases. However, when a Co-Ni-Mo film is formed via a Cr underlayer by a sputtering method in oxygen-containing Ar or pure Ar gas as in the present invention, MO is 4at compared to Co-Ni. % or more, the corrosion resistance worsened on the contrary. In fact, Co
o, seN io, am/ Cr medium and Mo, W 1
Coo, ssN i (1,84/
FIG. 3 shows the corrosion resistance of the Cr film in the salt spray test.

As described above, the reason why the corrosion resistance deteriorates due to the addition of Mo and W is that Co-Ni-Mo* is formed by sputtering in Ar gas or Ar gas containing oxygen.
This is because when a Co-Ni-W magnetic film is formed through a Cr underlayer, the crystal grains of the magnetic layer become finer, and Mo and W segregate as a result at the grain boundaries, forming local batteries. In fact, in Figure 5 (Co o, eeN i O, 84
) The results of Auger spectroscopy analysis of a 0.11M Oo, x/Cr thin film after a salt spray test are shown, and it can be seen that oxidation has progressed to the inside of the film. On the other hand, although the corrosion resistance is degraded by the addition of Mo and W, Mo is present at the grain boundaries.

Because the magnetic interaction between crystal grains for W segregation is weakened, the spread of the zigzag domain in the magnetization transition region during recording becomes smaller with the amount of Mo and W added, and the noise becomes smaller. It was revealed by am. Here, this effect was remarkable when the amount of MO or W added was 4 at% or more. If the amount added exceeds 11 at %, the magnetization of the magnetic film decreases, the reproduction quality deteriorates, and the S/N ratio of the system deteriorates, which is not desirable.

This effect was also observed when AQ, Si, and Cu were used as additives, but the 0 effect, which was most remarkable when A n and M op W were used as additives,
It is more noticeable and particularly preferable when it is contained in the magnetic film from t% to 20at%.

When the amount added is more than 20at%, the saturation magnetic flux density Bs
is not preferable because it becomes small.

Further elements such as Zr, Ti, Hf, etc. are added to the magnetic layer.
By adding t% or more and 15 at% or less, a passive film is formed on the surface of the magnetic film, suppressing the deterioration of corrosion resistance caused by the addition of MO and W, and improving the corrosion resistance overall compared to Co-Ni. Can be done.

The above effects apply not only when using Cr)IR as the base but also when M
o, W and CrTi, Cr-Ni,
Cr-S i , Mo-S i , W-T
i, Mo alloy such as Cr, Mo alloy, W
It was also approved as an alloy substrate. This is Co-Ni-
A11y Co-Ni-Mo, Go-Ni
-W alloy has high crystal consistency with Cr, Mo+W, and alloys whose main components are Co-N1-AQ, Co-Ni-M
This is because the C-axis of the o, Co-N1-W magnetic film is oriented toward the in-plane component, so that the characteristics as a magnetic recording medium are improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 11
is a non-magnetic substrate made of Af1 alloy etc., 12゜12' is N
Non-magnetic plating layer 13.1 made of i-P, Ni-W-P or an alloy containing these as main components
3' is a magnetic control layer made of Cr, Mo, W, etc., or an alloy containing these as main components; 14.14'
is a magnetic layer consisting of Co, Ni, and AQ or Mo or W, and Zr, Ti, Hf, etc., and 15 and 15' are C
, B, BaC.

The protective lubricant layer is made of 5i-C or the like, and each layer is formed as shown below. Outer diameter 130nn+Φ, inner diameter 4
0mΦ, 1.9m thick AQ alloy substrate, 20 on top of 11
μm non-magnetic 12 wt% P-Ni plating layer 12,1
2', the surface is roughened to a center line average surface roughness of 4 nm.
It was mirror polished to a thickness of 15 μm. This substrate was sputtered using an RF sputtering device at a substrate temperature of 150°C and an Ar gas pressure of 15°C.
mTorr, RF input power 2'? After forming 2,500 Cr, MO, or W thin films at J/d to obtain a magnetically controlled non-magnetic film of 513°13', a film thickness of 600° (C) was formed under the same conditions.

o, oaN io, sa) O*1111 Z r
oso7M o o, os or (Coo, saN
io, as) osaaZ ro, o7A Qo, os
Or (Co o, eeN io, sa) o, a
s Z r 0.07W0.0+5 Magnetic 914.14'
was formed. Furthermore, the substrate temperature was 150°C using a DC magnetron sputtering device.

A protective lubricant layer 15.15' of carbon having a thickness of 400 mm was formed at an Ar gas pressure of 10 mTorr and an input power of 4 W/cd.

Comparative Example 1 The magnetic layers 14 and 14' in FIG. 1 were made of Sn, Ta, Nb, Cu, V with a thickness of 600 mm
@5at% added to Go and Ni (Co
o, ssN io, as) o, saZ ro, o7 A magnetic disk having the same configuration as Example 1 except that the magnetic layer was used was fabricated as Comparative Example 1.

Comparative Example 2 The magnetic layers 14, 14' in FIG.
r 0.0? A magnetic disk having the same configuration as Example 1 except for the magnetic layer was produced as Comparative Example 2.

The recording and reproducing characteristics of the magnetic recording media obtained in each of the above-mentioned Examples 1 and Comparative Examples 1 and 2 are as follows: gap length Q, 6 μm;
A M n -Z n ferrite head with a track width of 30 μm allows a relative speed of 20 m/s and a spacing of 0.
Evaluation was made at 2 μm. Table 1 shows the resulting media noise and S/N ratio.

The frequency band during noise measurement was 20 M) (z).

Ta, Nb, Cu, V, A in G o -N i -Zr
Q.

It can be seen that by adding Mo and W, the noise level is reduced and the S/N is improved. Among them, AQ,
When Mo and W were added, the effect was remarkable and the highest medium S/N was obtained. Here, these media were heated to 60°C.
Corrosion resistance was evaluated in a high-temperature constant temperature furnace at 80% RH, and no increase in errors was observed for any of the media even after 3 weeks, indicating good corrosion resistance.Results of 8 or higher indicate that the nonmagnetic layer for controlling Cr magnetism M o , W e Cr -T with the same film thickness instead of
The same results were obtained using Cr-8i and Cr-8i layers.

Example 2 A with an outer diameter of 130 mmφ, an inner diameter of 40 tmφ, and a thickness of 1.9 mm
20 μm non-magnetic 12wt% P on Q alloy substrate 11
After the -Ni plating layers 12, 12' were formed, the surface was polished in the circumferential direction so that minute scratches with a center line average surface roughness of 7 nm were formed to 10 μm.

A substrate temperature of 150° C. and an Ar gas pressure of 20 mTorr were applied onto this substrate using a DC magnetron sputtering device.

The film thickness of CR thin film is 5000 at DC input power of 2W/cd.

2000 people, 1000 people, 500 people; After changing the thickness to 100 people and making the magnetic control layer 13.13'.

Furthermore, under the same conditions, a film thickness of 400 people (Co o, as N
i o, as) o, aa Z r 0.07M O0
,0! II (Co o,eo N i O+40)0
．． 811Z ro, osM oo, zo, (Coo
, soN io, ao) 0.117Zro, oaMo
o, oa, (Coo, asNio, aa) o, aa
ZrO,07M O0,0111 (Co o, aoN
i o, 1o) oaa3Z r'0.05Wo, xo,
(Coo, 5oNio, 5o)o, a7Zro,o
A 14.14' aW6.04 magnetic layer was formed. Furthermore, the substrate temperature was increased to 150°C using a DC magnetron sputtering device.
°C, Ar gas pressure 10 mTorr, input power 8w/
A C protective lubricant layer 15.15' with a thickness of 450 mm was formed at d, and finally a polar liquid lubricant layer with a thickness of 40 mm was formed to obtain a magnetic disk. The S/N ratio increased with the thickness of the Cr film, but all values were good at 6.5 or higher, and the corrosion resistance was also good.
o, aoN i o, go, Coo, BsN i O
,llll5. This was better than the media using CoO, soNiO*40 magnetic films, and no increase in errors was observed for 4 weeks in a high temperature and constant humidity test at 50'C and 85% RH.

Example 3 After making the layers 11, 12, 12', and 13° 13' in FIG. 1 the same as in Example 1, the conditions were the same as in Example 1 except that 02 was mixed with Ar as the sputtering gas. By forming the 14.14' layer, the magnetic layers in Examples 1 and 2 contained oxygen in an amount of 0.1 at% or more and 30 at% or less. 'N! The medium S/N increases with addition of elemental content, and in both cases the S/N is 7.
A value of 5 or more was particularly good, but when the value of ◯ exceeded 20 at%, the reproduction output decreased significantly and the overall S/N decreased, which was not preferable.

Example 4 Outer diameter 130+mO, inner diameter 40m++ O1 thickness 1,9
・20 μm non-magnetic 12w on the m AQ alloy substrate 11
After forming the t%P-Ni plating layer 12.12', the surface was mirror polished to a center line average surface roughness of 3 nm.
It was set as μm. A substrate temperature of 150'C1Ar gas pressure of 15 mTo was applied onto this substrate using a DC magnetron sputtering device.
rr, 250 Cr thin film with RF input power 2 W/cd
After forming a magnetic control non-magnetic layer 13° 13',
Under the same conditions, the film thickness was 500 people (Co o, eoNio,
io) oaaaT i 0.07M Ookai ost (
Co o, eo N io, io) o, aaHf
Q, 07M OOsO81 (Co oaeoN i
o, to) o, aa Z ro, zzM o o
, oa*(Coo, eoN io, to) o, asZ
ro, o7A Qo, o5゜(Co oaseN i
o, as) oaezZ ro, oaA Q OsO
4,゛(Coo,aoN io,io) o,ssZ
ro, xoA Q O, 07゜ (Co o, so N
i o, ao) o, as T i O, O? W
0.04 t (Co oaaoN io, go)
o, ssHf 0.07M O, oa @N11
4,14' formed, ri,":! Rani, '11J I
:, DC? The substrate temperature was 150"C using the Gnetron Batter apparatus.

The characteristics of the 0 discs with a C protective lubricant layer of 15.15' formed at an Ar gas pressure of 5 mTorr and input power of 4 W/cd are high with S/N of 6.5 or more, and the earth resistance was also prototyped under the same conditions. C o o,eoN i 0e40@ Co
O@allN io, as, Co o, aoN i
40'
C. No increase in error was observed during 4 weeks in a high temperature and constant humidity test at 90% RH.

Example 5 A with an outer diameter of 130 mmφ, an inner diameter of 40+nmφ, and a thickness of 1.9 m
1 alloy substrate 11 with 20 μm of non-magnetic 12 wt% P
After forming the -Ni plating layers 12, 12', the surfaces were polished to a thickness of 15 μm by making minute scratches in the circumferential direction with a center line average surface roughness of 4 ohm. DC on this board
The substrate temperature was 150℃ using a magnetron sputtering device.
r Gas pressure 15mTorr, RF input power 2W/-M
After forming a 3,000-layer O or W thin film to form a magnetism control non-magnetic layer 13.13', a film thickness of 750-layer (C) was formed under the same conditions.
oo, a.

Nio, 1o)o, 5sZro, oyAQo, oa,
(Coo, 5oNio, ao) o, sa Z r
O, 07M Oo, os* (Co oaaoN i
o, 1o) o, 5sZro, otWo, os* (C
oo, aoNio, 1o)o, a4Z ro, itA
Qo, o+m (Coo, soN io, a
o) o, a4Zro, zzMoo, oa, (C
oo, aoNio, go)o, aaZ ro, tzWo
EOA magnetic layers 14 and 14' were formed.

Furthermore, using a DC magnetron sputtering device, the substrate temperature was 150°C, the Ar gas pressure was 5 mTorr, and the input power was 4 W/d.
A C protective lubricant layer 15°15' with a thickness of 500 mm was formed, and finally a polar liquid lubricant layer with a thickness of 30 mm was formed to make a magnetic disk.The characteristics of the 0 disks are that the S/N is 6. 5
C o o, e, which was prototyped under the same conditions with high corrosion resistance.
oN i O,40,C.

. , aoN io, and so, and no increase in errors was observed in a high temperature and constant humidity test at 40° C. and 90° C. RH for 4 weeks.

〔Effect of the invention〕

As explained above, according to the present invention, in a magnetic recording medium having a metal-based magnetic thin film on a non-magnetic substrate, the magnetic thin film is composed of Co, Ni, at least one of Z r * Ti * Hf, and A. By adding at least one of 11 v M o +W, Co-
To provide a magnetic recording medium that reduces noise level and improves S/N without deteriorating the good magnetic properties of a Ni-based alloy magnetic thin film, and has good corrosion resistance, high performance, and high reliability. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a new view of a magnetic disk according to an embodiment of the present invention, FIG. 2 is a diagram showing the magnetic characteristics of the magnetic disk, etc. of the present invention, and FIG. 3 is a diagram showing the results of a salt spray test. FIG. 4 is a diagram showing the magnetic characteristics of the magnetic disk of the present invention when Mo is added, and FIG. 5 is a diagram showing the Auger profile of the magnetic disk of the present invention. 11...Substrate, 12.12'...Nonmagnetic plating layer,
13.13'...magnetic control nonmagnetic layer, 14.14'□
--First l $2vE3”

Claims (1)

[Claims] 1. In a magnetic recording medium in which a magnetic layer is formed on a non-magnetic substrate, the magnetic layer is mainly made of Co, Ni, Al, and Mo.
, W, and the content of Ni is 34 at% or more and 55 at% or less with respect to Co, and the content of Al, Mo, and W is 3.5 at% with respect to the total amount of Co and Ni. % or more and 30 at% or less. 2. The content of Al, Mo, and W is 4 at% or more 11a
2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is t% or less. 3. The magnetic layer further includes Co and Ni as well as Al and Mo.
, containing at least one of Zr, Ti, and Hf in an amount of 2 at% or more and 15 at% or less with respect to the total amount of at least one of W. The magnetic recording medium described in . 4. The magnetic layer further contains oxygen in an amount of 0.1 at% to 20 at% based on the total amount of Co, Ni, and other metals.
The magnetic recording medium according to any one of paragraphs. 5. An intermediate layer of 100 Å or more and 5000 Å or more of any one of Cr, Mo, W, or an alloy containing these as main components is interposed between the magnetic recording medium and the nonmagnetic substrate. Claims 1 to 4
The magnetic recording medium according to any one of paragraphs.