JPS61283031A - Production of vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To mass-produce efficiently the title high-performance recording medium having a high vertical-to-horizontal residual magnetization ratio by separating the vertically magnetized film forming process by sputtering into two stages and forming the first thin film and the second thin film respectively at a specified initial incident angle and in specified film thickness. CONSTITUTION:A feromagnetic metal is coated by sputtering on a nonmagnetic substrate 1 traveling at constant speed at an angle smaller than the incident angle theta1 to form the first thin film 21 having >=1 vertical-to-horizontal residual magnetization ratio and wherein crystals can be epitaxially grown. A ferromagnetic metal is coated by sputtering on the first thin film 21 to form the second thin film 22 at an incident angle of theta2b (theta2>>theta1) and crystals are epitaxially grown at t deposition rate considerably higher than that of the first thin film 21. Besides, the first thin film 21 is preferably formed in >=0.07mum thickness with the initial incident angle theta1 of <=15 deg. and a counter target system is favorably used to sputter the ferromagnetic metal. Since the process for forming a vertically magnetized film by sputtering is thus separated into two stages, a thin film having almost >=1 vertical-to-horizontal residual magnetization ratio can be efficiently formed with a high deposition rate.

Description

DETAILED DESCRIPTION OF THE INVENTION G) Industrial Application Field The present invention relates to a method of manufacturing a perpendicular magnetic recording medium by sputtering, which is suitable for mass production.

(b) Conventional technology As shown in Fig. 6, a perpendicular Magnetic recording media have a large residual magnetic flux density and are suitable for high-density recording.

For example, it has been proposed to apply facing target sputtering and magnetron sputtering as a method for forming a magnetized film such as co-cr at high speed on a non-magnetic substrate such as a plastic film such as PET, polyamide, or polyimide. ing. (Magazine “Applied Physics Vol. 48 No. 6
Jij, pp. 557-561, "Trends in New Sputter Forming Technology") FIG. 7 is a schematic diagram of a magnetic tape manufacturing apparatus using a general facing target sputtering method.

After using this device, first evacuate the vacuum chamber sufficiently, then use the Ar
Introduce gas and use sputtering power source (4) to target +
51 [5)' (For example, when a negative high voltage is applied to the co-ar joining plate sc, Ar gas is ionized and a plasma discharge occurs. When these positively charged Ar ions collide with the target, the surface of the target is A magnetized film such as Co-0r is formed on a non-magnetic substrate (1) where particles are sputtered and transferred at a constant speed by a can roller (6).A part of the surface of the can roller (6) is then used as a can mask. (
When the angle of incidence of the sputtered metal on the non-magnetic substrate (1) coated with 9) and guided by the can roller (6) as wire scraps is controlled, a perpendicularly magnetized film is formed on the substrate.

In FIG. 7, (7) indicates a supply roller, (8) a take-up roller, and αI(11'!i) a magnet for plasma convergence.

Limiting the initial incident angle θ1 of sputtered particles deposited on the nonmagnetic substrate (1) to a certain value or less is essential for forming a high-performance perpendicularly magnetized film.

On the other hand, if the initial incident angle θ1 is made small, the sputtered metal (
This leaves the problem that the rate of deposition of particles) on the non-magnetic substrate deteriorates, resulting in a significant drop in mass production efficiency.

(/Sai Problems to be Solved by the Invention The present invention provides high-performance perpendicular magnetic recording media that can be mass-produced by preventing a decrease in deposition efficiency on a non-magnetic substrate due to limitations on the initial incident angle θ1 of sputtered particles. A method for manufacturing the same is provided.

2) Means for solving the problem: Sputtered ferromagnetic metal is deposited on the non-magnetic substrate, which is transported at a constant speed, at an incident angle of 01 or less, and the vertical to horizontal remanent magnetization ratio is 1 or more. At the same time, a sputtered ferromagnetic metal is formed on the first thin film at an incident angle θ2 (however, θ
The second thin film is deposited at an angle of θ1) and grown epitaxially at a considerably higher deposition rate than the first thin film.
Forms a thin film.

More specifically, when forming a perpendicularly magnetized film by sputtering, this film forming process is divided into two steps: first, a first thin film is formed with a thickness of 0.07 μm or more at an initial incident angle of 0115° or less;
A second thin film is formed thereon to have a required film thickness t at an initial incident angle of 0115° or more.

(e) Effect When forming the first thin film on a tape base such as a polyimide film, by sputtering a ferromagnetic metal at an incident angle of 01 or less, the vertical to horizontal remanent magnetization ratio is increased at some sacrifice of the deposition rate. 1 or more to form a thin film that enables epitaxial crystal growth.

After that, when a ferromagnetic metal is sputtered at a high deposition rate on the first thin film at an incident angle θ in the relationship lJ*>>θl and a second thin film is formed by epitaxial crystal growth, the vertical to horizontal residual magnetization A thin film with a ratio of 1 or more can be efficiently formed at a high deposition rate.

(f) Examples Experiments that form the basis of the present invention (1) When sputtering Co-Cr onto a polyimide film base using the facing target sputtering apparatus shown in FIG. The relationship between the residual magnetization ratio MY/ME of the co-Cr film formed in the above was measured. FIG. 2 shows the measurement results with the initial incident angle θ1 on the horizontal axis and the residual magnetization ratio MY/MH on the vertical axis.

As is clear from this figure, the smaller the initial incident angle θ1, the
The residual magnetization ratio MY/MH of the co-Cr film increases. M
Since the condition for a perpendicularly magnetized film is that V/MH is 1 or more, as is clear from Figure 2, it is necessary to limit the initial incident angle θ1 to within 15° in order to obtain a co-Orr directly magnetized film. It turns out that there is.

(2) Similarly, when sputtering co-Cr onto a polyimide film base using the apparatus shown in Figure @7, the initial incident angle θ1 and the co
-The relationship between the deposition efficiency of the Cr film was measured. FIG. 3 shows the relationship between the initial incident angle θ1 (horizontal axis) and the deposition efficiency of the co-Cr film (vertical axis).

Due to the structure of the sputtering device shown in Fig. 7, the initial incident angle θ1 = 45
° is equivalent to the state with the can mask (9) removed. Here, the deposition efficiency when the can mask (9) was removed was standardized as 1. As can be seen from this figure, when the initial incident angle θ1=15° (ie, Mv/MH=1), the deposition efficiency is 0.7. In order to obtain a higher performance Co-0r perpendicular magnetization film with MY/MH of 1.5 or more (the larger MY/MH is, the more suitable it is for high recording density), the initial incident angle θ1 is set to 5° as shown in Figure 2. However, in this case, the deposition efficiency decreases to 0.5 or less.

From the above two experiments (11+21), in order to form a high-performance perpendicularly magnetized film on a moving non-magnetic substrate by high-speed sputtering, it is necessary to reduce the initial incident angle θ1 of the sputtered particles, and as a result, the sputtered particles It turns out that there are contradictory factors that reduce the deposition efficiency.

(3) Based on the above experimental results, the present inventors deposited the first thin film @ (Fig. 4) by sputtering at a small initial incident angle when sputtering Co-Or onto a polyimide film base. Seshime 1 The first method that enables epitaxial crystal growth with a vertical to horizontal residual magnetization ratio of 1 or more.
If a thin film is formed and then a second thin film (Fig. 4) is deposited on top of it by sputtering at an angle of θ〉〉θl, a thin film with a vertical to horizontal residual magnetization ratio of 1 or more can be efficiently formed. Based on the prediction that Co
A first thin film ① of -0r film is formed with various thicknesses, and further thereon is formed at an initial incidence angle of 61. When the second thin film @ of the Co-0r film is formed at =45° so that the total thickness t is 0.3 μm, the film thickness of the first thin film and the residual magnetization ratio of the full-layer Co-Cr film MY/
I sought a relationship with MH. FIG. 5 shows the results of experiment (3), with the horizontal axis representing the thickness of the first thin film and the vertical axis representing the vertical to horizontal residual magnetization ratio MV/MH.

From the diagram, it can be seen that in order to obtain a (F)Co-Cr film with MY/MH of 1 or more, the thickness of the first thin film should be 0.07 μm or more. When the thickness of the first thin film is 0.1 μm or more, MV/
MH becomes maximum value 1.5. In this way, if the first thin film is formed with a sufficiently small initial angle of incidence θ1, the crystal grains will easily grow perpendicular to the film surface (and furthermore, the second thin film will be formed on top of it with the initial angle of incidence θ1 as large as possible). However, since the second thin film grows epitaxially on top of the W11 thin film,
The second thin film also becomes a crystal grain layer with good vertical orientation, and as a result, a film with a large residual magnetization ratio MY/ME can be obtained. Therefore, since the second thin film can be formed with high deposition efficiency, mass productivity of high-performance perpendicular magnetic recording media is improved.

Manufacturing Apparatus FIG. 1 shows an embodiment of an apparatus for carrying out the manufacturing method of the present invention. This apparatus basically employs a facing target type sputtering apparatus.

In this device, a Co-Cr magnet is provided in the center of the vacuum chamber (3) with a permanent magnet α00G' for plasma focusing on the back side.
An opposing target (5H5, etc.) is arranged, and a pair of can rollers +6) +61' are arranged facing the left and right openings. The polyimide film (1) that is transferred by scraping the surface of each can roller is a supply roll (7) - a can roller (6) - a guide roll 011 (Ill (111 (11)).
It is transported at a substantially constant speed along the path of 1-can roll (6)'-take-up roll (8).

The polyimide film (1) guided along the curved surface of the can roller 161 f6)' is guided such that the same surface faces the opening side of the sputtering device <S>.

The angle of incidence of the sputtered particles onto both can rolls fil T6 can be adjusted using the can mask (91 (91')).

In the embodiment, the can mask (9) on the supply roll (7) side
The initial incident angle θ1(a) of the can mask (9)' on the winding roller (8) side was set to 45°. After evacuating the inside of the vacuum chamber to lX10 T-orr, Ar gas was introduced to make the temperature 2X10'rorr, and the temperature of the can roller +61 +61' was set to 170°C, and the polyamide film was fed at a feeding rate of 60 cII/mi, n. While moving at a sputtering power density of 38 W/d,
When a Cr film is formed by sputtering, a Co--Cr perpendicular magnetization film with a film thickness of 0.3 μm and a residual magnetization ratio MV/MH of 1.5 is obtained.

From FIG. 3, the film deposition efficiency when the initial incident angle θ1 is 5° is 172 when θ1 = 45°, so in the above example, the first thin film formed at θi, +11 = 5°. The film thicknesses of the second thin film formed at an angle of 01-45° are 0.1 μm and 0.2 μm, respectively. This is the 6th
This is consistent with the results shown in the figure. According to experiments conducted by the inventors, it has been confirmed that a high-performance Co-0r perpendicular magnetic recording medium can be manufactured at a sufficiently high base film feeding speed.

In the above embodiment, a case has been described in which a Co-0r film is formed on a plastic film by a facing target sputtering method, but the present invention is not limited to this. Co
A similar effect can be obtained with a perpendicular magnetization film such as -Cjr-Rh.

(g) Effects of the Invention According to the present invention, it is possible to provide a method for mass-producing a high-performance perpendicular magnetic recording medium with a high vertical to horizontal residual magnetic susceptibility with high efficiency.

[Brief explanation of drawings]

Figures 1 to 5 all relate to the present invention; Figure 1 is a schematic diagram of an apparatus for carrying out the method of the present invention, and Figure 2 is an initial incident angle θ.
Figure 3 is a diagram showing the relationship between the initial incidence angle 01 and thin film deposition efficiency, and Figure 4 is the relationship between vertical and horizontal remanent magnetization ratios for the first thin film thickness vs. C0-cr. FIG. 5, which is a diagram showing the relationship between magnetization ratios, is a cross-sectional view of a magnetic recording medium. 6 and 7 relate to a conventional example, with FIG. 6 being a sectional view of a magnetic recording medium, and FIG. 7 being a schematic diagram of a facing target type sputtering apparatus.

Claims (3)

[Claims] (1) In a method of manufacturing a perpendicular magnetic recording medium in which a ferromagnetic metal film is formed on a non-magnetic substrate by sputtering, the sputtered ferromagnetic metal is transferred to the non-magnetic substrate at a constant speed at an incident angle of θ_1 or less. forming a first thin film that is deposited at an angle, has a vertical to horizontal residual magnetization ratio of 1 or more, and enables epitaxial crystal growth of sputtered particles deposited thereon in a later step; Sputtered ferromagnetic metal is placed on top at an incident angle of θ_2 (where θ_2≫θ_1
), and the second thin film is formed by epitaxial crystal growth at a considerably higher deposition rate than the first thin film. (2) The method for manufacturing a perpendicular magnetic recording medium according to claim 1, wherein the first thin film formed at an initial incidence angle of θ_1≦15° has a thickness of 0.07 μm or more. (3) A method for manufacturing a perpendicular magnetic recording medium according to claim 1 or 2, characterized in that a facing target method is adopted for sputtering the ferromagnetic metal.