JPS62262247A - Production of magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve the magnetic characteristics of a vertically magnetized film by heating a transparent org. substrate prior to film formation in a film forming device in the case of forming the film of a magneto-optical recording medium contg. a recording layer consisting of the vertically magnetized film on said substrate. CONSTITUTION:The transparent org. substrate 1 is heated prior to the film formation in the film forming device in the case of forming the film of the magneto-optical recording medium 3 contg. the recording layer consisting of the vertically magnetized film on said substrate. More specifically, the substrate is heated at the substrate temp. or above in the stage of the film formation to degas the adsorptive material prior to the film formation. The taking of the adsorptive material of the substrate into the recording medium through the pinholes existing in a dielectric 2 which is a protective layer and the taking of the adsorptive material into the recording medium 3 by evaporating from the substrate part covered by a substrate holder are thereby prevented and the magneto-optical characteristics of the medium are improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a magneto-optical disk that is used in a rewritable magneto-optical disk and can be read using a magneto-optic effect such as a magnetic Kerr rotation effect or a Faraday effect. The present invention relates to a method of manufacturing a recording medium.

(Prior Art) Conventionally, a magneto-optical recording medium that records information thermomagnetically and reproduces it magneto-optically has a protective layer made of a dielectric material and a recording layer of a perpendicularly magnetized film on a transparent organic substrate or glass substrate. , reflective layers made of metal films, etc., have been formed in various combinations by sputtering or vapor deposition. The perpendicular magnetization film is GdTbFe.

DyFe, GdCo, TbCo, TbDyFe, TbF
Rare earth-transition metal amorphous alloy thin films such as eCo are considered promising because they are suitable for mass production and have low readout noise.

As the disk substrate, glass substrates are easily damaged and expensive, so PC (polycarbonate), PMMA,
Organic substrates such as epoxy are mainly used.

(Problems to be Solved by the Invention) Magnetic properties such as coercive force and perpendicular magnetic anisotropy of the perpendicularly magnetized film used in the recording layer are affected by oxidation. Particularly in the case of a rare earth-transition metal based vertical film, the perpendicular magnetic anisotropy deteriorates even if the film is left in the air for a few days because the rare earth metal is easily oxidized.

In order to prevent oxidation after film formation of a magneto-optical recording medium, the recording layer is sandwiched between protective layers made of dielectric material, and this has been effective. However, the magnetic properties of the perpendicularly magnetized film deteriorate due to evaporation of adsorbed substances from the organic substrate due to an increase in substrate temperature during film formation.

An object of the present invention is to provide a method for manufacturing a magneto-optical recording medium with excellent magnetic properties.

(Means for Solving the Problems) When the present invention forms a magneto-optical recording medium including a recording layer of a perpendicularly magnetized film on a transparent organic substrate, the substrate is heated in a film forming apparatus before film formation. It is characterized by carrying out the following.

(Function) The following two factors are believed to be responsible for the deterioration of the magnetic properties of the magneto-optical recording medium on the organic substrate during film formation.

(1,) Adsorbed substances on the substrate are taken into the recording medium through pinholes present in the dielectric material that is the protective layer.

(2,) The adsorbed substance evaporates from the substrate portion covered by the substrate holder and is incorporated into the recording medium.

In order to prevent these, it is effective to heat the substrate before film formation to a temperature higher than the substrate temperature during film formation to degas the adsorbed substance.

(Example) FIG. 1 shows an example of the present invention, in which 1 is a transparent organic substrate (PMMA). 2 is a dielectric layer (siN)
, 3 is a magneto-optical recording medium layer (TbFeCo), and 4 is a dielectric layer (SiN). A magnetron sputtering device was used for film formation.

Figure 2 shows the square shape of the Kerr hysteresis loop of TbFeCo due to the substrate incidence when the film was formed after heating the substrate at 60°C for 3 hours before film formation in the film forming apparatus, and when the film was formed on an untreated substrate. It is in ratio S. When the substrate is heated at 60'C for 3 hours, S* is good at 0.9 or more, whereas when untreated, S* is small and distributed in the radial direction. Even when a PC is used as the substrate, it is effective to heat the substrate before film formation as in the case where a PMMA substrate is used.

(Effects of the Invention) Adsorbed substances on the organic substrate are evaporated by heating the substrate before film formation in the film forming apparatus. This can prevent adsorbed substances on the substrate from being incorporated into the magneto-optical recording medium during film formation, and the magnetic properties of the medium can be improved compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a magneto-optical disk showing an embodiment of the present invention, and FIG. 2 is a squareness ratio S* of the Kerr hysteresis loop.
- is a diagram. 1: Organic substrate 2: Dielectric layer 3: Magneto-optical layer 1 Self-recording medium layer 4: Dielectric layer Fig. 1

Claims (1)

[Claims] Manufacture of a magneto-optical recording medium, characterized in that when a magneto-optical recording medium including a recording layer of a perpendicularly magnetized film is formed on a transparent organic substrate, the substrate is heated in a film forming apparatus before film formation. Method.