JPS6234348A - Manufacture of photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To execute work without leaking a vacuum tank at all, and to reduce the cost by forming in advance a conductive material film on other part than a recording part of a recording surface side of a transparent substrate, bringing the conductive material film into contact with a jig for fixing the transparent substrate, and also forming a transparent conductive film on the whole transparent substrate. CONSTITUTION:Silver paste 10 is applied thinly to other part than a recording part of a recording surface side on a polycarbonate transparent substrate 9 at first. Thereafter, the substrate 9 is fixed to a substrate holer 2 by using a fixing jig 8. Next, sputtering is started by using an ITO target 4 and rotating the substrate holder 2 in a vacuum, and an ITO transparent conductive film 11 if formed. Subsequently, sputtering is started by rotating the substrate holder 2 without breaking the vacuum and applying a DC bias voltage, and a photomagnetic recording film 12 is formed. According to such constitution, there is no necessity for resetting the substrate by leaking a vacuum tank to the atmospheric pressure, therefore, the time for forming vacuum is enough by once, and the cost of a medium can be reduced remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a magneto-optical recording medium by a vacuum film forming method.

[Summary of the invention]

The present invention is a method for manufacturing a magneto-optical recording medium capable of recording, reproducing, and erasing, in which a conductor is prepared in advance in a region other than the recording portion on the recording surface side of a transparent substrate for forming an amorphous magneto-optical recording film, and Transparent conductor t# on conductor! By creating X, it is possible to apply a DC bias voltage to the transparent substrate during the creation of an amorphous magneto-optical recording film without breaking the vacuum chamber.

[Conventional technology]

Conventionally, the materials used for magneto-optical recording media are mainly KT&
-Fs, Gd-Tb-Fls-Go, Tb-P
e-cm, Ckd-Tb-F, , Od-11
Rare earth-transition metals such as 1g, Gd-c (, etc.) are mainstream.In addition, there were magneto-optical recording media using the Faraday effect such as Mn-B1, but the film was polycrystalline and had a lot of noise. The above-mentioned rare earth-transition metals have become mainstream because they have many drawbacks such as high Curie temperature and 〈h in writing.

This has the advantage that it is amorphous, has no grain boundary noise, has a Curie temperature of 120° C. to 200° C., and can be written satisfactorily even with a semiconductor laser. The mainstream method for producing these amorphous rare earth-transition metal films is to form them on a substrate using ionized thin film formation techniques such as sputtering, ion blating, and ion beam evaporation. It is known to apply a DC bias voltage to a metal substrate holder for the purpose of improving the performance. However, in this case, since a transparent substrate such as glass or plastic is used as an electrical insulator, a bias voltage is not directly applied to the substrate, and no improvement in film quality can be expected.Therefore, AJ,
If a metal film such as Cw is formed and brought into contact with the substrate holder, the DC bias voltage can be increased? Can be applied to the substrate.

However, since data recording, reproduction, and erasing are normally performed using laser light from the substrate side, AJ,
(A laser beam cannot pass through a metal such as 4th grade, so recording, reproducing,
Erasing becomes impossible, so the next thing to consider is the above-mentioned 8! - This is a method of forming a film on transparent conductive vx1 instead of a metal thin film such as CU. (Unexamined Japanese Patent Publication No. 58-2
15744) [Problems and objectives to be solved by the invention] However, in the above-mentioned conventional technology, after a conductive film is vacuum-formed on a substrate, the vacuum inside the vacuum chamber is once leaked, and the conductive film and the substrate holder are brought into contact with each other. Then, the magneto-optical recording film must be deposited while evacuation is applied again and a DC bias voltage is applied. In other words, evacuation is required twice to create a magneto-optical recording medium, which increases costs. If this is explained in detail, it will be as shown in Fig. 3. This figure is a manufacturing process diagram of a conventional DC sputtering method, and is shown schematically. First, as shown in ), a transparent conductive film for the wings is first formed. Here, 31 is a substrate holder, and the wings are transparent substrates (glass, PC, PMMA, epoxy resin, etc.)
, 34 is a substrate fixing jig, and the transparent conductive film of the wing is not in contact with that substrate fixing jig. This is because the Fi film cannot be formed around the jig due to the effect of the substrate fixing jig. It is. Therefore, we leaked the vacuum chamber once and brought the transparent conductive film into contact with the substrate holder of 31, which is shown in (b).
This is the 0 board fixing jig. This jig is slightly larger than jig 34 and is in contact with that transparent conductive film.

Then, while vacuuming again and applying a DC bias voltage, magneto-optical recording V! (c) is the Xft film formed, and 36 is a magneto-optical recording film (Tb7g, Tb?#Co).

GdTbF, etc.), 37 is l
)C power supply.

In this way, in the conventional technology, the conductive film and the substrate fixing oil At-
In order to make contact, the vacuum chamber must be leaked at least once, which greatly increases costs. Since this company's magneto-optical recording medium does not become a directly magnetized film with a good initial vacuum level (lxl (J"'Torr'Torr), most of the cost of the medium is the amortized cost of the equipment. This leads to a huge amount of loss.The present invention is intended to solve these problems, and its purpose is to continuously conduct transparent conduction without leaking the vacuum chamber even once! The purpose of this method is to provide an inexpensive magneto-optical recording medium by completely forming the magneto-optical recording film and by applying a substrate KDC bias voltage during the formation of the magneto-optical recording film.

Means for Solving Problem c] The method for manufacturing a magneto-optical recording medium of the present invention is a method for manufacturing an amorphous magneto-optical recording medium in which the direction of magnetization is perpendicular to the film rrJVc and has two directions: upward and downward. In addition to the recording area on the recording surface side of the transparent substrate on which the amorphous magneto-optical recording film is to be created, a conductive film is prepared in advance, and a jig for fixing the conductive film and the transparent substrate is brought into contact with each other. It is assumed that transparent conductivity is formed throughout the entire transparent substrate.

[Effect]

The above structure of the present invention is shown in FIG. 2, which is a sectional view of the manufacturing process of the magneto-optical recording medium according to the present invention. first)
As shown in , in addition to the recording part on the recording surface side of the transparent substrate B,
A conductive film is prepared in advance, and this conductive film is brought into contact with a substrate fixing jig to be fixed to the transparent substrate 221. This substrate fixing jig is used to fix the substrate holder 211c. , of course, is in contact with the substrate holder.

Then, as shown in (b), a transparent conductive film 25 is formed over the entire transparent substrate. By doing so, the transparent conductive film 5 can come into contact with the roughly prepared conductive body film. In other words, the DC bias voltage applied to the substrate holder 21 can be applied to the transparent substrate. This is because the conductor @ prepared in advance is sufficiently thin, so that the transparent conductive film can sufficiently wrap around and come into contact with the conductor film. On the other hand, in the conventional method, the substrate fixing jig and the transparent conductive film are considerably larger than the conductive film and cannot be wrapped around even if the transparent conductive film is f''F-bottomed. There is no contact.

〔Example〕

FIG. 1 is a cross-sectional view of a magneto-optical recording medium and a manufacturing apparatus according to an embodiment of the present invention, in which 2 is rotatable with a substrate holder, and 3 is grounded with an lFi vacuum hinoki. Voltage can be applied using a DC bias power supply. 4 is the engineering target (for transparent conductor 1! film), and 5 is ? - Target 6 is a T6 chip for magneto-optical recording film. These targets are subjected to DC sputtering by a DC power supply 7. Also, A with 8t:f board fixing jig!
9 is a transparent substrate (polycarbonate substrate),
1 ( ] is a conductive conductive film Ag paste), 11 is a transparent conductive film (
0 film) e 12 is magneto-optical recording [IR (T67g
@:Tbrich composition).

First, a thin layer of silver paste 10 is applied to a portion of the polycarbonate transparent substrate 9 other than the recording portion on the recording surface side (the chucking portion on the inner circumference in this case). Then people! Using a substrate fixing jig, the substrate holder fi°-2 and the polycarbonate transparent substrate 9 are fixed. In this state, conduction between the substrate holder 2 and the silver base 10 has been established. Then, using the target of 4, the initial vacuum degree I x 10-'T
After evacuation to ort-, Af voltage, 5m Torr
, 02 partial pressure 8×10''''TOf''r was introduced, Pow
Sputtering was started while rotating the substrate holder at gr 100 W, and a TO transparent conductive film 11 of 30 OA was formed. This state is the substrate holder 2 and the TO transparent conductive film 11.
This means that continuity has been established. Then, without breaking the 1 vacuum, the initial vacuum degree was again evacuated until it reached I x 10-' Torr, an Af voltage of a5 m Torr was introduced, and P
Sputtering was started while rotating the substrate holder under power of 100 W. At this time, a voltage of -707 is applied to the substrate holder using a DC bias source 3t-. Then, a T6F magneto-optical recording film 12 of 100 OA was fabricated.

Here, the Kerr rotation angle measurement diagram of the magneto-optical recording medium prepared according to the present invention is shown in FIG. FIG. 4(b) shows a measurement diagram of the Kerr rotation angle when a TbF magneto-optical recording film was prepared while applying . From this figure, it can be seen that the medium produced by the method of the present invention has very good squareness of Kerhis helisis, and a bias voltage is applied. On the other hand, in the case of hysteresis in (b), no bias voltage is applied, and in the medium to which a bias voltage is applied according to the method of the present invention, a slight improvement in Kerr rotation angle and a decrease in coercive force are observed. This is considered to be because oxygen in the TbF# film was driven out due to the bias voltage being applied.

〔Effect of the invention〕

As described above, according to the '$ invention, the conductive film is entirely formed in advance on the recording surface side of the transparent substrate on which the amorphous magneto-optical recording film is to be made, and the conductive film and the transparent substrate are bonded together. 1. By keeping the fixing jig in contact with each other, then forming a transparent conductive film over the entire transparent substrate, and further forming an amorphous magneto-optical recording film while applying a DC bias voltage to the transparent substrate. A DC bias voltage can be applied to the magneto-optical recording medium, and improvements in the Kerr rotation angle and squareness of the magneto-optical recording medium can be seen.Furthermore, in order to apply the bias voltage, the vacuum chamber can be leaked to atmospheric pressure. There is no need to reset the substrate, and since transparent conductive films and amorphous magneto-optical recording can be created continuously, vacuuming only needs to be done once, which can significantly reduce the cost of the medium. .

Here, the extent to which the present invention reduces costs is shown in FIG. 5, which is a graph of device depreciation per substrate with respect to the initial degree of vacuum. This cost calculation is based on the assumption that the sputtering equipment costs 100 million yen per month and operates for 2 Ahr/day, and can sputter three sheets of 120 uφ diameter at a time. As is clear from this figure, the initial degree of vacuum is usually l
Since the film is formed at less than X 1 (J-'Tarr), the cost of the present invention, which requires only one evacuation, is 3,216 yen/sheet, but the cost of the conventional method, which requires two evacuations, is twice as high as 6,432 yen/sheet. It can be seen that the cost reduction achieved by the present invention is significant since it costs 10,000 yen per sheet.

Incidentally, although silver paste was used as the conductor used in this example, any conductive film such as carbon paste is suitable. NiZ? L.O.

It can be anything such as s3o, , Tho, etc. Also, the magneto-optical recording film can be Tb1! In addition to '6 membrane, Tb'H'
aCo, GdT61Fg.

Anything is acceptable as long as the main component is a rare earth-transition metal such as GdTbF or Go, and the structure of the medium may be 31'! 1.4 layers, etc., after the nine-layer recording film t! j′B1. Even when the body film, reflective film, etc. are laminated, there is no spacing, and the transparent substrate can also be made of polymethyl methacrylate, epoxy resin, glass, etc. in addition to polycarbonate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magneto-optical recording medium and a manufacturing apparatus. FIGS. 2(α) and 2(b) are cross-sectional views of the manufacturing process of the magneto-optical recording medium. FIGS. 3(b) to 3(c) are cross-sectional views of the manufacturing process of the DC sputtering method according to the prior art. Figure 4 (b)) Kerr rotation angle measurement diagram where Fi bias voltage could be applied. FIG. 4(b) is a diagram of Kerr rotation angle measurement where no bias voltage could be applied. FIG. 5 is a diagram showing the depreciation of the device per substrate with respect to the initial degree of vacuum. 1...Vacuum chamber 2・e・Substrate holder 3...DC bias power supply 4...TO target (for transparent conductive film) 5...F
- Target transfer...Tb chip 7...DC power supply 8...Substrate fixing jig 9-...Transparent substrate (polycarbonate substrate) lO...
Silver paste 11...To transparent conductive film 12...TbFIl magneto-optical recording film 21...Substrate holder n...Transparent substrate holder...Conductor film...Substrate fixing jig 25+1.・Transparent conductive film 31...Substrate holder! ...Transparent substrate (glass, PC, PMMA, epoxy resin, etc.)...Transparent conductive film...Substrate fixing jig 35...Substrate fixing jig 36@--Magneto-optical recording@( 'rbyg,'rbygc
Rare earth-transition metal film such as o, GdT6pg)

Claims (1)

[Claims] In a method for manufacturing an amorphous magneto-optical recording medium in which the direction of magnetization is perpendicular to the film surface and has a binary value of upward or downward, a recording portion on the recording surface side of a transparent substrate for forming the amorphous magneto-optical recording film. In addition, a conductive film is created in advance, the conductive film and a jig for fixing the transparent substrate are brought into contact with each other, a transparent conductive film is then created on the entire transparent substrate, and a DC is applied to the transparent substrate. A method for manufacturing a magneto-optical recording medium, comprising forming the amorphous magneto-optical recording film while applying a bias voltage.