JPH0330925B2 - - Google Patents

Description

[Detailed Description of the Invention] <Summary> When attaching a magnetic film by the sputtering method, as in the spin cord method, the thickness of the formed film is sloped in the middle between the inner diameter and the outer diameter, and the difference in circumferential speed is It is possible to compensate for the sensitivity associated with this.

Further, the degree of the above-mentioned inclination can be changed.

<Industrial Application Field> The present invention relates to a method of manufacturing a magnetic disk (recording medium) for a magnetic disk device, and in particular to a method of manufacturing a magnetic disk (recording medium) for a magnetic disk device, in particular, the film thickness is varied in a radial direction in order to compensate for the characteristics related to the difference in peripheral speed in the radial direction. The present invention relates to a method for manufacturing magnetic disks using a sputtering method.

<Prior art> These magnetic disks have a magnetic recording film formed on a non-magnetic disc made of aluminum or the like, and write and read data using a magnetic head while rotating. Since the peripheral speed is different between the outside and inside, there is a problem that the output on the outside side is large and the overwriting characteristics are poor, so by making the film thickness on the outside side thinner according to the distance from the rotation center, it can be made uniform. I've come to try to change it.

This is due to the centrifugal force that increases as the radius increases and the film forming material applied to the disc substrate while rotating at high speed, which is commonly known as the spin code method, which was used in the era when recording films were formed by painting. In order to balance the hardening time, the selection of mixed solvent and spindle rotation speed were varied to produce a recording film with controlled film thickness in the radial direction.

However, film disks used in places where the recording density is even higher are coated with evaporation or sputtering.
-Ni-Crx Co-Ni magnetic film, as well as Ni, permalloy, etc. are deposited, so these techniques cannot be used, and an appropriate method for controlling the film thickness distribution in the radial direction has been sought.

<Problems with conventional technology> Film formation using vapor deposition or sputtering methods basically forms a uniform film, and it is difficult to control the film to have a gradient in the distribution in the radial direction. If you try to do this, there will be non-uniformity in the circumferential direction as well. On the other hand, in order to basically establish a system in which one head can access tracks from the inside to the outside, the output level must be corrected using other methods, such as interlocking control such as track monitoring and gain correction. It's not very interesting because it's added.

<Solution Means> In view of the above, the purpose of the present application is to provide a method for manufacturing a magnetic disk in which the radial film thickness distribution can be controlled even in the sputtering method.

Therefore, in this application, the necessary sputtering apparatus includes a sputtering source (a source of film forming material) having a long side B _Y larger than the outer shape of the target disk substrate, and a width Bx smaller than the outer shape Do of the disk substrate;
If you want to specify a relative position parallel to the spatter source at a predetermined distance (on a parallel plane), hold the disk substrate on the moving axis that is approximately parallel to the width direction and the center of the long side approximately coincides with the center of the disk substrate. , movement and positioning/stopping, a means for rotating around the center of the disk substrate, and a function for sputtering and stopping are at least necessary.In this application, on the premise of these, the center of the disk substrate is set on the movement axis. Select a position that is offset by a predetermined amount δ from the center of the sputter source in the width direction, and perform sputtering while rotating the sputtering source (monitor the film thickness if necessary), and when a predetermined thickness distribution is achieved. The aim is to resolve this by terminating the issue.

<Function> If the above process is carried out using the above means, firstly, the film thickness distribution in the circumferential direction can be made uniform by rotating the disk substrate, and secondly, the spatter source can be Because there is a concentration distribution
If Zs is constant, when the above offset δ is zero,
Thirdly, the width Bx of the spatter source is smaller than the outer diameter Do of the target disk substrate (Bx/Do
(smaller), the above-mentioned maximum slope becomes larger, and fourthly, by increasing the offset δ, the distribution can be changed in the direction in which the slope of the film thickness distribution decreases. When combined as elements, it is possible to form sputtered films with various radial inclinations and uniform distribution in the circumferential direction with respect to the disk substrate using the same device depending on the selection of conditions.

<Effect> By combining the sputtered material with a specific magnetic head used in the target device and sputtering under conditions that provide a magnetic disk (film thickness gradient) with uniform output characteristics, it is possible to create a magnetic disc that meets the purpose. Magnetic disks can be manufactured easily and reproducibly, and the versatility of the manufacturing equipment can also be maintained.

<Example> FIG. 1 is a basic explanatory diagram of the present invention, and FIG. 2 is a supplementary diagram of FIG. The relative positional relationship and dimensions under the intervention are explained using a coordinate system in which directions are defined by orthogonal XYZ axes.

Under the above definition, the center Os of the sputtering source 1 is located at Os = (Xs, O, Zs), and the distribution center O's of the sputtering particles is located at O's = (Xs, O, O). The center of the moving stage holding disk 2, that is, the center Od or Odδ of the held disk 2, is Odx = (X, O, O) or Odδ = (Xs
-δ, O, O), and disk 2 is configured to be rotatable around Odδ or Odx, and can be stopped at a selected position on stage 3, and Zs can be changed. It is also configured so that it can be sputtered. Then, disk 2 is sputtered while rotating at a selected position of Zs and δ in the middle of the stage, and disk 2 is defined in the radial direction.
For example, if the layer thickness is expressed with a T suffix between Ri (corresponding to the innermost side of the track) and Ro (corresponding to the outermost side of the track), then T _Ri > T _Rp , and for example, the characteristics of the magnetic disk head and Ro /Ri ratio, and select conditions that achieve a predetermined film thickness ratio between T _Ri /T _Rp = 1.5 to 1.8, which makes the output characteristics uniform, and T _Rp .
A desired magnetic disk medium is manufactured by sputtering a magnetic recording film (or its base film) to a thickness of approximately 5×10 ^-8 to 20×10 ^-8 m. be.

The figures below in Figure 3 are intended to explain the characteristics of the movement of each parameter that governs the conditions when selecting the conditions, and Figure 3 shows the parameters.
It concerns Zs.

As shown in Figures 3 and 5, as Zs increases, under other conditions the same, the amount of adhesion spreads and tends to become somewhat lower, and the ratio between T _Rp and T _Rd becomes smaller and the peak becomes gentler. However, as shown in Figure 5, if it is increased too much, the adhesion rate will suddenly decrease, so it cannot be changed too much as a parameter.

Furthermore, Figure 4 is a graph summarizing the results of an experimental example of T _R /T _Rp using the ratio of the width Bx of the evaporation source (Bxe does not change much as mentioned above) and the outer diameter Do of the disk spatter as a parameter. Yes, but Bx/Do
It can be seen that as T R becomes smaller, T _R /T _Rp becomes smaller and the slope of the film thickness distribution in the radial direction becomes steeper.

FIG. 6 is a graph summarizing experimental examples of the distribution of deposited film thickness using the offset amount δ as a parameter. As the offset amount δ increases, the position of the maximum film thickness shifts to the center of the disk 2 (R=o). It has both a tendency to move toward the outside diameter from the position of , and a tendency to shift the value of T _Ri /T _Rp to a smaller value, but the parameters that change the value of T _Ri /T _Rp are as shown in Figure 4 above. Bx/Do is sharper than Bx/Do, and by mainly searching for conditions using both or one of these two parameters as perturbation parameters, it is possible to obtain the desired inner and outer diameter film thickness with the same sputtering device (inner and outer diameters, It is possible to manufacture a magnetic disk (with uniform head detection sensitivity). Moreover, FIG. 7 summarizes the conditions that are made dimensionless by combining these to make it easier to find them.

Furthermore, since this method allows conditions to be found within a predetermined range, it is possible to manufacture magnetic disks with different specifications using the same manufacturing equipment with good reproducibility. It is also possible to adjust the sensitivity balance using the ratio.

What is the dimension in the Y direction in this example?
The relationship between Do and B _Y is explained in two dimensions as B _Y ≫Do, but if B _Y ≧Do, the slope of the mountain in Fig. 4 will be slightly steeper, but the same way will be used to create the data for perseveration. It can be put to practical use because it satisfies the reproduction conditions as long as it is experimented and redefined.

<Effects> As explained above, according to the present invention, by selecting the dominant parameters δ and Bx/Do, the radial film thickness ratio of the magnetic disk can be reproducibly changed even during sputtering manufacturing. This has the effect that it becomes possible to easily compensate for the difference in sensitivity when accessing the inner and outer diameter portions with the film thickness depending on the conditions of the disk device or the head used, even in the case of sputter disks.
This has the effect that it is possible to efficiently and inexpensively provide a spatter disk device whose gain does not change depending on the access, is uniform in the radial direction, and has excellent resolution.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of an embodiment that also serves as the basic configuration of the present invention, Figure 2 is a supplementary diagram of Figure 1, Figures 3 and 4.
5, 6, and 7 are supplementary explanatory diagrams of an embodiment of the present invention, and are explanatory diagrams relating to perturbation parameters governing the radial distribution of film thickness in sputtering. In addition, 1 in the figure is a spatter source, 2 is a disk, and 3 is a sputter source.
indicates a moving stage.

Claims (1)

[Claims] 1. A sputter source having a band-shaped width Bx and a constant composition, and a disk substrate held at a predetermined distance from the sputter source in the X and Z directions, moved in the X direction, and rotated around the axis. In the method for manufacturing a magnetic disk, the width Bx of the sputtering source is set smaller than the outer diameter of the disk substrate, and the width Bx of the sputtering source is set smaller than the outer diameter of the disk substrate. A method for manufacturing a magnetic disk, characterized in that sputtering is performed while rotating the disk substrate at a position whose center is offset by a predetermined amount in the X direction from the center of the width of the sputter source.