JPS63220418A - Magnetic disk and production thereof - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk having superior magnetic characteristics with improved productivity by forming a Cr underlayer and coating the lateral parts of the columnar grains of the Cr underlayer with Cr oxide. CONSTITUTION:A Cr underlayer 5 is formed on a substrate 1 with a polished underlayer 3 in-between and oxygen is diffused in the grain boundaries of the columnar grains 7 of the Cr underlayer 5 by heat treatment in a gaseous oxygen atmosphere. After only oxide formed on the top of the Cr underlayer 5 is removed by sputter etching with gaseous Ar, a Co-based magnetic layer 11 is formed. The lateral parts of the columnar grains 7 of the Cr underlayer 5 are coated with oxide 9 and Cr faces having a crystal structure are isolated from each other. Since the Co-based magnetic layer 11 is formed on the Cr underlayer 5, the columnar grains of the magnetic layer 11 performed epitaxial growth on the Cr faces and a magnetically insulated magnetic film is obtd. Thus, large coercive force can be obtd. even in case of a thin Cr film and productivity in an in-line apparatus can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of Industry 1-] The present invention relates to a magnetic disk and a method for manufacturing the same. More specifically, the present invention relates to a magnetic disk with excellent productivity and magnetic properties, and a method for manufacturing the same.

[Prior Art] In recent years, in order to cope with higher recording density on magnetic disks, magnetic disks having a magnetic layer made of a ferromagnetic metal thin film have been studied.

For example, in the vapor deposition method, J, DAVAL & D, R
ANDET.

IEEE Trans,Magn,,Vol,NAG
-G, No, 4. p, p, 7G8. December1
97G, by depositing a Cr underlayer on the substrate and then further depositing a CO magnetic layer.
There is a technique in which the easy axis of magnetization of the CO magnetic layer is directed in the in-plane direction and Cr grains l- are epitaxially grown.

In this case, the Co layered on the Cr columnar particles of the base layer
Good magnetic properties cannot be obtained unless the laser is magnetically insulated. However, in order to magnetically insulate the 00 particles, C
r The thickness of the underlayer must be 0.1 μm or more. Therefore, a large amount of time was required to form the Cr underlayer itself.

Moreover, in order to form a Cr underlayer of this thickness, the substrate temperature must be raised to about 300°C. Substrates that can withstand such high temperatures are limited to inorganic materials such as aluminum or glass;
f-near 7 molecule substrate cannot be used.

[Problems to be Solved by the Invention] An object of the present invention is to solve the drawbacks in terms of productivity of the prior art described in Section 2, and thereby provide a magnetic disk with excellent magnetic properties.

[Means for Solving the Problems] As a means for solving the above-mentioned problems and also achieving the object of the present invention, the present invention provides a method in which an underlayer and a magnetic layer are formed on a non-magnetic substrate in this order. The present invention provides a magnetic disk in which the underlayer is made of Cr, and the side surfaces of the columnar grains of the Cr underlayer are coated with Cr oxide.

Substrate -1- has a non-magnetic disk made of aluminum alloy, glass, organic material, etc. as a base, and is further provided with an alumite treatment layer or a base polishing layer such as a nickel-phosphorus alloy for surface polishing if necessary. The upper end of the chromium underlayer is formed by forming a chromium underlayer, and then performing a heat treatment in an oxygen gas atmosphere to diffuse oxygen into the columnar grain boundaries of the chromium underlayer, and by sputter etching treatment using argon gas. After performing a process to remove only the oxides formed on the surface, a magnetic layer mainly composed of CO is formed, so that the side surfaces of the columnar particles of the chromium underlayer are covered with oxides, improving magnetic properties. Chromium planes with a crystal structure due to are isolated from each other. C on top of this
When a magnetic layer containing O as a main component is formed, the columnar grains of the magnetic layer grow epitaxially on the chromium surface, resulting in a magnetic film with good magnetic insulation. Therefore, it is possible to obtain a large coercive force even with a thin chromium film, and the productivity of in-line equipment can be improved.

It was confirmed that when an oxide layer is present on the entire surface of the Cr columnar grains and a Co magnetic layer is laminated thereon, the magnetic properties are not improved because the crystal orientation of the Co grains p deteriorates. As a result of the inventor's intensive research, it was found that by removing the Cr oxide layer on the end face of the Cr columnar particles, pure carbon was produced.
It has been discovered that when the surface of the r-particle is exposed and ferromagnetic metal particles such as CO are epitaxially grown on the exposed surface, the crystal orientation of the ferromagnetic metal particles becomes better.

- The heat treatment described above may be performed by any means such as directly heating the substrate holder or using an infrared lamp. If the heating temperature is too low, it will not have the effect of diffusing oxygen, and if it is too high, the base polishing will occur. Since there is a risk of deterioration of the layer, the temperature is preferably within the range of 100°C to 350°C.

□Also, the sputter etching process using argon gas is performed using high frequency power, microwave power, DC power, AC power, etc., and in particular, high frequency power of 13.58 MHz is preferably used because it is relatively easy to handle. The high frequency power at this time ranges from 0゜lW/cm2 to 3W/cI.
It is used in the range of I2, especially from 0-3W/cm2 to 1.
It is preferable to use it within the range of 5 W/cs2.

1- The substrate made of non-magnetic material mentioned above includes non-magnetic metal such as an aluminum disk, various glasses, disks made of organic material, etc., and the base layer to be polished includes NiPs alumite, TiO2 ,5i0
It includes all materials with high hardness that can be subjected to hardening such as 2nd grade.

Further, as a magnetic layer containing Co in the -L form, co is used.

Co-N1v Co-Cr5 Co-P, Go-Ni
-P+ Co-Ni-Cr+ Co-Pte Co -
It is formed by a method such as depositing a ferromagnetic material such as VLCo-Ni-CL Co-Fe-Ni by physical vapor deposition such as sputtering, vacuum evaporation, or ion blating.

As an alternative method, a Cr-based oil layer is formed on a substrate made of a non-magnetic material, a base layer is formed on the substrate, and the surface thereof is polished. The surface of the magnetic layer is treated with glow discharge using nitrogen gas,
Furthermore, by forming the surface protective layer, the surface layer of the magnetic layer mainly composed of cobalt, which is epitaxially grown on the columnar grains of the Cr-based underlayer, is nitrided, and the magnetic insulation properties are improved. Since it has a nitrided surface layer, the adhesiveness of the surface protective layer formed on the magnetic layer -1- is +;jLl-
do.

The side portions of this alternative Cr underlayer may be coated with a Cr oxide layer. However, even if the side surfaces of the Cr underlayer are not coated with oxide, the surfaces of the magnetic particles are coated with nitride, so that the magnetic particles are magnetically insulated. In order to achieve even higher magnetic insulation, Cr
It is preferable that the side surface portion of the underlayer be coated with a Cr oxide layer and the surface of the magnetic particles be coated with nitride.

By improving the magnetic insulating layer in this way, the coercive force of the magnetic layer increases, and for this reason, it is possible to reduce the thickness of the Cr-based underlayer and lower the substrate temperature when forming the Cr-based underlayer or magnetic layer. This makes it possible to improve productivity such as in-line formation. Further, the nitrogen on the surface of the magnetic layer and the surface protective layer are strongly bonded, thereby improving durability.

” Glow discharge treatment using double nitrogen gas is a high-frequency,
High frequency power of 13.56 MHz, which is generated by a power source such as microwave, direct current, or alternating current, is particularly preferably used because it is relatively easy to handle.

The high frequency power at this time is 0. IW/cm2 to 5W/c
It is preferably used within the range of 0.5 W/cm 2 to 3 W/cm 2 . If this high frequency power is lower than 0.1W/cm2, the result of the process will be 1-
If it is higher than 5 W/cm2, the nitride layer will grow excessively and the magnetic properties will deteriorate.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to the following examples.

Jitsronko 1- 3.5 inch diameter aluminum disc, 20μ
An N1-P plating layer with a thickness of m was formed, and the surface of the plating layer was mirror polished. This disk was then loaded into a high frequency magnetron sputtering device and sputtered at 6xlO-3 Torr.
Under an argon gas atmosphere of 60%
It was formed so that there would be 0 people. Next, the substrate was heated to 250°C under an oxygen gas atmosphere at atmospheric pressure. After heat treatment to a temperature of U degrees, the surface of the underlayer was etched by applying high frequency power of 1.2 W/cm2 in an argon gas atmosphere of 2X10-2 Torr.
7XlO-JTo
Sputtering in an argon gas atmosphere of 800
&M disks were fabricated by forming magnetic layers.

FIG. 1 shows a partial cross-sectional view of the manufactured magnetic disk.

In Figure 1, l is an aluminum disk and 3
is an N1-P plating layer, and 5 is a Cr-underlayer.

The side surface of the Cr pillar-F7 constituting the base layer 5 is made of Cr.
Covered with an oxide layer 9. Co is in the L part of the Cr underlayer.
-Ni magnetic layer 11 is laminated. This Go--Ni magnetic layer is in direct contact with one end surface of the Cr columnar particles 7 that is not covered with oxide.

The chromium underlayer and cobalt-nickel magnetic layer in Example 1 were formed by heating and evaporating chromium and cobal+--nickel alloy under a vacuum of λ 1 x 10-5 Torr, and the heat treatment was carried out at lkw. A magnetic disk was produced in the same manner as in Example 1, except that the method of irradiation with an infrared lamp was used.

The film thickness of the chromium underlayer in Examples 1 and 2 was 200 mm.
A magnetic disk was produced in the same manner as in Examples 1 and 2, except that the number of disks was 0.

Comparative Example A magnetic disk was produced in the same manner as in Example 1.2 except that the heat treatment and etching treatment were omitted.

10 m of magnetic disks obtained in each example and comparative example.
The samples were cut into pieces with a diameter of m, and their magnetic properties were measured and compared using a sample vibrating magnetometer.

The results are summarized in Table 1 below.

As is clear from the table, the magnetic disks obtained in Examples 1 and 2 had a higher coercive force than the magnetic disks obtained in Comparative Examples 1 to 4 even with the same thickness of the magnetic layer. The improvement in magnetic properties also improves productivity.

Jitsukoretsu J- N
After forming a 1-P plating layer to a thickness of 20 μm,
This surface was mirror polished. Next, this substrate was loaded into a high frequency magnetron sputtering device, and 5xlO-JT
A base layer made of Cr was deposited under an Ar gas atmosphere of 50% orr.
It was formed so that there would be 0 people. Next, a magnetic layer made of Go-Ni (8G-20 at%) was deposited 7X on the Cr underlayer.
After forming 450 people under an Ar gas atmosphere at I O-J Torr, glow discharge treatment was performed by applying high frequency power at 1.2 W/cm2 under an N2 gas atmosphere at 1 x 10''2 Torr. Furthermore, a surface protective layer made of carbon was formed by sputtering using graphite as a target.

FIG. 2 shows a partial cross-sectional view of the manufactured magnetic disk.

In FIG. 2, 1 is an aluminum alloy disk, 3 is an N1-P plating layer, and 5 is a Cr underlayer. A Co--Ni magnetic layer 11 is laminated on top of this Cr underlayer. The surface of the magnetic material grains 13 constituting this Co--Ni magnetic layer is covered with a nitride layer 15. A carbon surface protection layer 17 is further laminated on the magnetic layer 1-.

Firstly, the substrate on which the N1-P plating layer in Example 3 was formed was loaded into a vacuum evaporation apparatus, and Cr and Co-Ni (80-20 at%) were deposited in 1'C air at 1X10-5 Torr.
is heated and evaporated to form a 500 Cr layer and 500 Cr layer.
The o-Ni layer is laminated, and after glow discharge treatment, 5i0
A magnetic disk was produced in the same manner as in Example 1, except that a sputtering surface protective layer consisting of No. 2 was formed.

Magnetic disks were also produced in the same manner as in Examples 3 and 4, except that the glow discharge treatment using nitrogen gas in Examples 3 and 4 was omitted.

Regarding the magnetic disks obtained in each example and comparative example,
The magnetic properties were measured. In addition, a spherical sliding test using a 6 mm diameter steel ball as a friction body was conducted to evaluate durability. Durability was determined by measuring the number of times the protective layer or magnetic layer was slid until the friction coefficient suddenly increased and the protective layer or magnetic layer peeled off. °The results are shown in Table 2 below.

-12 As is clear from Table 12, the magnetic disks obtained in Examples 3 and 4 had a film thickness of about the same as the Cr layer magnetic layer thickness compared to the magnetic disks obtained in Comparative Examples 5 and 6. , Since the holding force is high, the Cr layer thickness can be reduced, in-line production becomes easier, and the sliding properties are improved and the durability is improved.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged cross-sectional view of the magnetic disk manufactured in Example 1, and FIG. 2 is a partially enlarged cross-sectional view of the magnetic disk manufactured in Example 3. DESCRIPTION OF SYMBOLS 1... Aluminum disk, 3... N1-P plating layer, 5... Cr base layer, 7... Cr columnar particles, 9...
・Cr oxide layer, 1.1all11 magnetic layer, 13-...
magnetic particles.

Claims (2)

[Claims] (1) In a magnetic disk in which an underlayer and a magnetic layer are laminated in this order on a nonmagnetic substrate, the underlayer is C
r, and the side portions of the columnar particles of this Cr underlayer are C.
A magnetic disk characterized by being coated with r-oxide. (2) In a method for manufacturing a magnetic disk having an underlayer made of Cr and a magnetic layer on a non-magnetic substrate, the underlayer is heat-treated in an oxygen gas atmosphere after forming the underlayer.
The entire surface of the columnar particles in the r underlayer is coated with Cr oxide, and after this heat treatment, the upper end surfaces of the columnar particles in the Cr underlayer are sputter-etched using argon gas to remove carbon on the upper end surface.
1. A method for manufacturing a magnetic disk, comprising removing an r-oxide film and then laminating a magnetic layer on the underlayer.