JPS5936329A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a homogeneously composed magnetic recording medium, by supplying continuously Cr particles in the range of specified diameters to an evaporation source, when Co and Cr are evaporated by electron-beam irradiation and a magnetic film consisting of Co and Cr as the main components is formed on a moving substrate. CONSTITUTION:A substrate 1 is transferred from a wind-off system 3 along a can 2, Co-Cr alloy powders 15 in the range of 2-6mm. average particle diameters are supplied to an evaporation source of the alloy 5 from an additional charging equipment, and an electron beam 9 is irradiated from an electron gun to deposit the generated vapor on the substrate 1 at an aperture of a mask 8. Otherwise, the evaporation source is divided into a Cr source 6 and a Co source 7, and the powdered Cr is feeded to the source 6 in the same manner. By this method, a change of the composition of a magnetic layer due to a decrease of Cr in the evaporation source which is based on the difference between the vapor pressures of Cr and Co is suppressed to a <=5% variation of the required composition, and a homogeneous ferromagnetic film extended over a long range is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium suitable for, for example, perpendicular magnetic recording.

Conventional configuration and its problems Perpendicular magnetic recording is effective when performing magnetic recording with a short recording wavelength. As a recording medium for perpendicular magnetic recording, there is a recording medium in which the direction of easy magnetization is perpendicular to the film surface. One of the recording media with such characteristics is a magnetic film that contains CO and C.
A recording medium containing r as a main component is used (hereinafter, this film will be referred to as a Co--Cr film).

Co--Cr can be produced by either a sputtering method or a vacuum evaporation method. Particularly, the latter method can increase the film formation rate to several thousand people/second and has high productivity. Figure 1 shows Co-Cr 1l by vacuum evaporation method.
An example of a method for manufacturing a long substrate is shown, and the substrate is unwound along the rotation direction 13 from the unwinding system 3 in a vacuum chamber 11 evacuated to a high vacuum by an exhaust system 12. The substrate 1 moves along the can 2, and is vacuum-deposited with a Co-Cr film by the CoCr alloy evaporation source 5 into which an electron beam 9 is incident from the electron gun 10 at the opening of the mask 8, and then transferred to the winding system 4Vζ winding system. On the other hand, as shown in FIG. 2, it is also possible to construct the evaporation source from two evaporation sources, a Cr evaporation source 6 and a CO evaporation source 7, and fabricate the Co--Cr film on the entire length substrate. Below, as shown in Fig. 1, there is a wide-source evaporation method in which the evaporation source is a CoCr alloy evaporation source, a method in which the evaporation source is composed of a CO evaporation source and a Cr evaporation source as shown in Fig. 2, and a full two-source evaporation method. call.

In the one-source deposition method, since the difference in vapor pressure between CO and Cr is large, the Cr component in the evaporation source decreases as the evaporation time progresses. Therefore, when a long Co-Cr film is produced, the film is to Cr
It comes to have a composition with few components. On the other hand, the two-source vapor deposition method allows the temperatures of the CO evaporation source and the Cr evaporation source to be controlled independently, which is advantageous for producing a film whose composition is stable over a long length.

(Since Cr is a sublimable metal, if you try to make the entire Co-Cr film by -source evaporation method VC, the third
As shown in the figure, even if the shape of the Cr surface 18 in the V-coat 16 is flat at the start of vapor deposition, the electron beam 9
The surface of the Cr 17 is dug down, and the Cr surface 19 becomes uneven after a period of time. Accordingly, the Ct vapor distribution curve 20 at the start of vapor deposition changes like the Vitill line 21 for the Cr vapor after time elapses, causing a compositional change in the film deposited on the substrate. In order to have sufficient recording and reproducing characteristics as a perpendicular magnetic recording medium, the compositional fluctuation of the Co--Cr film must be suppressed to within ±1% over the entire length of the long film. Now the composition of Co-Cr IIK is the general weight composition Cr20COs as a Co-Cr vertical film.

Then, in order to keep the composition variation within ±1 factor (Z), it is necessary that the variation in Cr precipitation rate be 1d, and the total length of the Co-Cr long film should be within ±5 inches. .

Purpose of the Invention The present invention provides a means to easily obtain a ferromagnetic film with a uniform composition over a long length when forming a ferromagnetic film for perpendicular recording, for example, containing CO and Cr as main components by vacuum evaporation. With the goal.

Composition of the invention The present invention uses a single-source deposition method or a two-source deposition method.

An evaporation source of Cr and Cr is irradiated with an electron beam and heated to generate vapor, and when forming a ferromagnetic film for perpendicular recording using Co, Cr'l (!l- as the main component) on a moving substrate. , C
oCx Alloy or Cr sole evaporation source V Granular Cr
This is to continuously add or replenish.

DESCRIPTION OF EMBODIMENTS According to the present invention, in the source evaporation N method VC, it is possible to keep the composition of the evaporation source constant by continuously adding granular Cr, and therefore it is possible to keep the composition of the evaporation source constant. - A Co--Cr film with a constant composition can be produced.

In the Ma/Dori source vapor H method, granular Cr is used as the Cr evaporation source.
By continuously supplying Cr, it is possible to prevent unevenness from occurring on the surface of the Cr evaporation source due to the electronic bean and to maintain a constant Cr vapor distribution shape. It is possible to fabricate a Co--Cr film with a constant composition.

As a result of experiments, it has been found that the shape of the added Cr is most preferably granular in order to reduce the influence of Cr on the shape of the vapor distribution when the Cr is added. Regarding the particle size, it was confirmed that the smaller the particle size, the smaller the heat capacity, and that the additionally added granular Cr did not affect the temperature of the surrounding Cr.

On the other hand, experiments have shown that if the particle size is made too small, the degree of scattering of the granular Cr by the impact of the electron beam becomes large, resulting in undesirable effects such as thermal damage to the substrate. Therefore, there is an optimum range for the particle size of the additionally added Cr. When we conducted an experiment to examine the optimum particle size, we found that the average particle size ('J 4 mm).

It was found that it is preferable to have a standard deviation of about 2 mm. Figure 4 shows the particle size on the horizontal axis and the fluctuation rate of the Cr precipitation rate on a substrate positioned 4 cm directly above the evaporation source on the vertical axis, with respect to VC when the average precipitation rate is 6008/sec. It is. As can be seen from Figure 4, the additionally charged Cr grain size was 4wn±2m.
In the range of m, it was possible to suppress the precipitation fluctuation rate within ±0.5 factors. However, when the additional Cr particles had a diameter of less than 2 mm, the degree of scattering of granular Cr due to the electron beam impact V was too large, causing thermal damage to the substrate.

Next, more specific embodiments of the present invention will be described. FIG. 6 shows an example in which one input of Cr0 is carried out in continuous winding vacuum deposition using a one-source deposition method.

As shown in the figure, the pudding substrate 1 unwound from the unwinding system 3 moves along the can 2, and receives additional injection of granular Cr15 by the Cr additional injection device @14 at the opening 1-j of the mask 8. A Co--Cr film is vacuum-deposited by a Co--Cr alloy evaporation source S, and then wound up by a winding system 4V.

Figure 6 shows how Cr was deposited during continuous vacuum evaporation using the second-stage evaporation method.
An example is shown below.

It should be noted that if the additional amount of Cr added is too large, it will take time to increase the temperature, and the fluctuation in the evaporation rate will increase.

When Cr is evaporated using an electron beam device with an output of 10 KW, the additional amount of input is 5 yAnI71, the height of the evaporation source is 4 cm, and the Cr on the substrate is positioned at K.
The precipitation rate fluctuates by a factor of ±0.5, and the additional input amount is 5
As a result of experiments, it was found that the Cr precipitation rate fluctuated by ±10% at 0y/min.

As a result of producing a Co-Cr film by continuous winding vacuum steaming with additional addition of Or according to the present invention,
It was found that a uniform composition could be obtained over a long length.
Jin. - In the case of the source evaporation method, the length is about 160 m by adding additional Cr and controlling the electron beam output at the same time.
A Co--Cr film having a compositional variation of ±i, o was obtained. In addition, in the case of the second-stage evaporation method, by adding additional Crf and H and simultaneously controlling the electron beam output of the Co evaporation source, a substrate with a length of about 200 yn can be coated with composition fluctuations of ±o and 9% Co-Cr. A membrane was obtained.

Effects of the Invention As is clear from the above description, the present invention makes it possible to easily obtain a long Co--Cr ferromagnetic film with a uniform V-stiffness composition, thereby mass-producing magnetic recording media with stable quality. This is extremely useful.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining the conventional method for manufacturing magnetic recording media, and FIG. 4
The figures are for explaining the production IJ of the present invention, and are diagrams showing the relationship between the grain size of additionally added Cr and the half value +iJ of the variation in the amount of Cr precipitated on the substrate, Figures 5 and 6. The figure is a diagram for explaining the method of manufacturing a magnetic recording medium according to the present invention. 1... Board, 2... Can, 3... Unwinding system,
4... Winding system, 5... CoCr alloy evaporation source, 6
...Cr evaporation source, 7...Co evaporation source, 8...
Mask, 9...Electron beam, 10...Electron gun, 11
・Vacuum chamber, 12... Exhaust system, 14... Cr additional injection device, 15... Granular Cr, 16...
・No. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 WJ3 Figure 4 Figure 132- Figure 5

Claims (3)

[Claims] (1) A Co and Cr evaporation source is heated by electron beam irradiation to generate vapor to form a ferromagnetic film containing Co and Cr as main components on a moving substrate, and the Cr evaporation source is A method for manufacturing a magnetic recording medium, characterized in that granular Cr is continuously replenished. (2) The method for manufacturing a magnetic recording medium according to claim 1, wherein the average particle size of the granular Cr is in the range of 2 to 6 mm. (3) The method for manufacturing a magnetic recording medium according to claim 1, wherein the ferromagnetic film is a perpendicular magnetization film that is easily magnetized in a direction perpendicular to the film surface.