JPH0221441A - Magneto-optical recording medium and its production - Google Patents

Abstract

PURPOSE:To obviate the deterioration of corrosion resistance by using one material selected from a strontium titanate compd. and barium titanate compd. or the mixed crystals of both as a protective film. CONSTITUTION:The protective film 13a is deposited on the surface of a sub strate 11 consisting of a polycarbonate resin. A magnetic film 15 is then deposited and formed on the surface of the protective film 13a by using a target for the magnetic film. The protective film 13b is in succession deposited and formed on the surface of the magnetic film 15 by the same film forming conditions as for the protective film 13a. The protective films 13a, 13b consist of the either one material selected from the strontium titanate compd. (SrTiOx) and the barium titanate compd. (BaTiOx) (where X denotes 2.7<=X<=3.0 value) or the mixed crystals composed of both thereof. The recording medium is consti tuted of such protective film material, by which >=2.2 refractive index (n) and <=0.03 coefft. (k) of light absorption are obtd. The deterioration in the corrosion resistance is obviated in this way.

Description

[Detailed description of the invention]

(Industrial Application Field) This invention relates to magneto-optical recording media, and in particular,
Carr (err) effect enhancement (Enhanc)
The present invention relates to a magneto-optical recording medium provided with a protective film having excellent protection properties. (Prior Art) Magneto-optical recording media (hereinafter sometimes simply referred to as recording media) are being actively researched and developed as high-intensity recording media equipped with a magnetic film that can be penetrated. Among the magneto-optical recording materials constituting the magnetic film of such recording media, amorphous alloys of rare earth metals and transition metals (hereinafter sometimes simply referred to as RE-TM gold alloys) have magnetization in the direction of magnetization. The perpendicular magnetization film is oriented perpendicularly to the film formation surface, the coercive force is as large as several Oe, the sputtering,
Since it is relatively easy to form a film using vacuum evaporation or other deposition techniques, it has the most research and practical application. However, the magnetic film made of RE-TM gold alloy has low corrosion resistance (see, for example, Document I: "Magneto-Optical Disk" (edited by Osamu Imamura, published by EU-Rikebus, p. 427)), and may have poor magneto-optical properties. It has the disadvantage that the effect (Kerr effect) is small. Therefore, a magnetic film made of RE-TM gold alloy is sandwiched between protective films made of various materials to prevent corrosion of the magnetic film and to
A structure is known that uses multiple reflections of light to increase the apparent rotation angle of the upper Kerr (Nierr) (cited above, p. 119). The conventional magneto-optical recording medium mentioned above will be explained below with reference to the drawings. FIG. 5 is an explanatory diagram showing a schematic cross section in order to explain an example of the configuration of a recording medium provided with a protective film.
Some hatching indicating the cross section is omitted. As can be understood from FIG. 5, the recording medium 17 is constructed by sequentially forming a protective film 13a, a magnetic film 15, and a protective film +3b on the surface of the substrate 11. Among these, the substrate 11 is made of, for example, polycarbonate resin, glass, epoxy resin, or any other suitable material, and has a disk shape. In addition, the protective II films 13a and +3b are, for example, 5iO1S.
iO□, /IuN, Si3N, , Au5iN,
Formed by depositing Au5iON or other overcoat material. As already mentioned, the application of this protective film is carried out, for example, by sputtering, vacuum evaporation or other application techniques depending on the material of which the protective film is made. In general, the magnetic film 15 is made of the above-mentioned RE-TM gold alloy, and examples of such alloy include Tb-Fe alloy, T
Various b-Co alloys, Tb-Fe-Co alloys, or other combinations of rare earth metals and transition metals are known. In the recording medium 17 having such a structure, the medium 17
The protective film 13a disposed on the reading side of the C/N ratio (Ca
Since this is a factor that affects the carrier/noise ratio (carrier/noise ratio), it is necessary to satisfy the following conditions. ■The apparent material must have a high refractive index to increase the Kerr rotation angle.■The wavelength of the light used for writing and reading (usually 750
- 900 (nm)) ■It must be a corrosion-resistant material that can protect the magnetic film from, for example, moisture in the environment in which the medium is used.Also, the protective film +3b must be made of at least the above-mentioned material. As long as the material satisfies the corrosion resistance shown in (■), it may be constructed of other materials that lack the conditions that bring about Kerr effect enhancement. Information is written on such a recording medium 17 by a thermomagnetic writing method using a laser beam narrowed to a spot diameter of about 1 (un) and an external magnetic field, and since it is the perpendicular magnetization film described above, 10a ( It is possible to record extremely high 9 degrees (bits/am2). Furthermore, it has the excellent feature that, in principle, erasing and rewriting can be repeated almost infinitely many times. (Problem to be Solved by the Invention) As can be understood from the explanation of the prior art mentioned in No. 1 above, the refractive index and light transmittance of the protective film in a magneto-optical recording medium have a large effect on the information writing and reading characteristics. Affect. Among these, considering the refractive index, for example, aluminum-based protective film materials (for example, the aforementioned AQ, N, A [SiN, A
u5iON) has a refractive index n of approximately 2, and is known as a material exhibiting a relatively high value among known materials. However, at present, with the development of various information devices, there is a demand for improved overall recording performance, and there is a problem that the Kerr effect enhancement is insufficient with the refractive index of conventionally known protective film materials. Furthermore, as described above, the protective film formed on the reading side of the magnetic film is required to have a small extinction coefficient k at the wavelength used for writing and reading information. This extinction coefficient includes the complex refractive index n-, which includes the refractive index n mentioned above.
In fact, the extinction coefficient of conventionally known protective film materials, which can be known as ki (i is an imaginary unit), has a value of about 10-1, but it is desired to set it to a much lower value. However, there has been a problem in that a protective film material that satisfies the requirements regarding refractive index n and extinction coefficient and also has excellent corrosion resistance has not been obtained. In view of the above-mentioned conventional problems, it is an object of the present invention to provide a highly reliable magneto-optical recording medium equipped with a protective film that satisfies the various requirements mentioned above, and a method suitable for manufacturing the medium. There is. (Means for Solving the Problem) In order to achieve this object, according to the magneto-optical recording medium according to the first invention of this application, a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate is provided. In magnetic recording media, the above-mentioned protective film is made of a strontium titanate compound (
SrTiOx) and barium titanate compounds (BaT
iOx) (where X represents a value of 2.7≦x≦3.0) or a mixed crystal of both. Further, according to the method for manufacturing a magneto-optical recording medium according to the second invention of this application, in manufacturing a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate, the above-mentioned protection is applied. The film was made of strontium titanate (SrTi
A film forming target made of either or both of barium titanate (8aTiO3) and titanium (Ti) or titanium oxide (TiOY).
) (where Y represents a positive number) is simultaneously deposited by sputtering. In general, according to the method for manufacturing a magneto-optical recording medium according to the third invention of this application, in manufacturing a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate, the above-mentioned method is performed. The protective film is made of strontium titanate (SrTi).
03) and barium titanate (BaTiO:+), or both of them, by sputtering in a mixed atmosphere of inert gas and oxygen. It is said that Further, according to the method for manufacturing a magneto-optical recording medium according to the fourth invention of this application, in manufacturing a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate, the above-mentioned protection is applied. The film was made of strontium titanate (SrTi
03) and barium titanate (8aTi03), or a film forming target made of either or both of titanium (Ti) or titanium oxide (TiCh).
) (wherein Y represents a positive number) is simultaneously deposited by sputtering in a mixed atmosphere of inert gas and oxygen. In addition, in the methods according to the second, third, and fourth inventions described above, the film-forming target made of both strontium titanate and barium titanate is one in which these two substances are constituted as a mixed crystal. It comprehensively represents the case where a film-forming target is used and the case where a total of two types of film-forming targets made of each substance are used at the same time. (Function) According to the magneto-optical recording medium according to the first invention of this application, by configuring the recording medium with the above-mentioned protective film material, the refractive index n is 2.2 or more and the extinction coefficient k is 0.03 or less. Therefore, there is no deterioration in corrosion resistance compared to conventional materials. Further, according to the method for manufacturing a magneto-optical recording medium according to the second invention of this application, as described above, the film formation target and the composition adjustment target are simultaneously sintered to form a protective film. A high refractive index and a low extinction coefficient can be achieved, and deterioration of corrosion resistance can be largely avoided. Among these characteristics, especially regarding the above-mentioned extinction coefficient k, the coefficient k can be set to O by increasing the proportion of oxygen in the target for composition adjustment, thereby realizing a substantially transparent protective film. can do. The operation of this manufacturing method is not clear, but by using the composition-adjusting cuget with the above-mentioned structure, it is possible to create a bond between the material that constitutes the film-forming target and the material that is deposited as a protective film. It is thought that the deviation in the stoichiometric composition of is compensated for. According to the method for manufacturing a magneto-optical recording medium according to the third invention of this application, as described above, only the film forming target is placed in a mixed atmosphere of an inert gas such as argon and oxygen. By forming a protective film by sputtering, a high refractive index and a low absorption coefficient can be achieved, and deterioration of corrosion resistance can be avoided. Among these characteristics, the above-mentioned extinction coefficient k (in particular, the coefficient kVo can be obtained by increasing the proportion of oxygen in the mixed atmosphere, and a substantially transparent protective film can be realized. Further, according to the method for manufacturing a magneto-optical recording medium according to the fourth invention of this application, as described above, the film-forming target and the composition adjustment target are simultaneously heated using an inert gas such as argon. By forming a protective film by sputtering in a mixed atmosphere of gas and oxygen, it is possible to achieve a high refractive index and a low extinction coefficient, and it is possible to roughly avoid deterioration of corrosion resistance. According to this method, as in the second and third inventions described above, the extinction coefficient can be set to 80 by increasing the proportion of oxygen in the composition adjustment target and the proportion of oxygen in the mixed atmosphere. (Embodiments) Examples of the invention according to this application will be described below with reference to the drawings. , will be explained using preferred numerical examples and other conditions within the scope of this invention,
It should be understood that these are merely examples, and that the present invention is not limited to these specific conditions. Comparative example and Example 1 having the structure shown
A total of 19 types of recording media, 18 to 18, were manufactured, various characteristics were measured, and comparative studies were conducted. In order to facilitate understanding of the explanations regarding these samples, the material composition, adhesion conditions, and property evaluation results of the recording medium for each sample are listed in a separate table on page 69. ratio 1

[Description of Manufacturing Conditions] First, in the recording medium according to this comparative example, a protective film 1 made of silicon monoxide (Sin) was formed on the surface of a substrate 11 made of polycarbonate resin by a conventionally well-known sputtering technique.
3a is deposited to a thickness of about 800 (λ). The film forming conditions at this time were to use a film forming target with a diameter of 126 (mm) made only of SiO, and an input power of 500 (W).
The experiment was conducted at an argon gas pressure of 3 (mTorr). Next, the composition ratio of chilled ram diiron: cobalt is 22 near 0.
:8 (ratio of the number of atoms) is prepared, and under the same sputtering conditions as above, the magnetic film 15 is deposited on the surface of the protective film 13a to a thickness of about 800. Adhesive formation. Subsequently, under the same conditions as the above-mentioned protective film 13a,
A protective film +3t) was deposited on the surface of the magnetic film 15 described above to a thickness of about 1000 (λ) to obtain a recording medium according to a comparative example. <Explanation of C/N ratio measurement procedure and measurement results> This C/N
In measuring the ratio, a recording medium according to a comparative example manufactured on a polycarbonate resin substrate was used as a sample according to the procedure described above, and the wavelength of the light used for writing was 830 (nm),
Rotation speed 900 (r, p, m,), duty -50 (%
), recording frequency 1.85 (MHz), recording power 7 (
mW) and then read out with a power of 1.6 (mW).
The C/N ratio was measured with a bandwidth of 30 (Hz). As a result, the C/N ratio of the recording medium according to the comparative example was 44.0.
(dB). Explanation of Corrosion Resistance Test Procedures and Measurement Results> In the corrosion resistance test, information was written in advance on the recording medium according to the comparative example, and the relative humidity was set to 80 (%) at a temperature of t60 ("G).
) conditions (hereinafter simply referred to as corrosion resistance test conditions).
Hold for 200 hours. Thereafter, the corrosion resistance was evaluated based on the result of measuring the rate at which the pre-written information was damaged after the corrosion resistance test (error rate) and the measurement result of the C7N ratio described above. As a result, the error rate is about 10-4, and C/
The N ratio was 44.0 (dB), the same as the value before the corrosion resistance test. Measurement procedure and results of complex refractive index In this measurement, a film thickness of 2000 (λ) of Si was deposited on the surface of the silicon wafer under the same deposition conditions as for the protective film described above.
A sample coated with O was prepared separately, and the complex refractive index n-k at a wavelength of 633 (nm) was measured using an ellipsometer.
i was measured. As a result, the complex refractive index was 1.90-0.10 i. Next, recording media according to Examples 1 to 4 in which strontium titanate (SrTiO3) 7a is used as a target for film formation will be described. In the recording medium according to this embodiment, a substrate 11 made of polycarbonate resin is formed by a conventionally well-known sputtering technique.
A protective film 13 at a thickness of approximately 800 (λ) is formed on the surface of the protective film 13at. The film forming conditions at this time were to use a film forming target with a diameter of 126 (mm) made only of SrTiO3, an input power of 500 (W), and an argon gas pressure of 3 (mm).
It was carried out as (Ding orr). Next, using the target for the magnetic film having the composition described above, the protective film 13a is sputtered under the same sputtering conditions as described above.
A magnetic film 15 with a film thickness of about 800 (λ) is deposited on the surface. Subsequently, a protective film +3b was deposited on the surface of the magnetic film 15 to a thickness of about 1000 (layers) under the same film-forming conditions as the protective film 13a described above, and the recording medium according to the example] was formed. Obtained. <Explanation of C/N ratio measurement procedure and measurement results> This Example 1
In measuring the C/N ratio of the recording medium according to Example 1, the recording medium according to Example 1, which was manufactured on a polycarbonate resin substrate, was used as a sample by the same procedure as the comparative example described above, and the light used for writing was measured. Wavelength 830 (nm), rotation speed 900 (
ρ, m, ), duty -50 (%), recording frequency 1
．． 85 (MHz), recording power 7 (mW), then read power 1.6 (mW), bandwidth 3
The C/N ratio was measured at 0 (Hz). As a result, the C/N ratio of the recording medium according to Example 1 was 47.
It was 5 (dB). Explanation of Corrosion Resistance Test Procedures and Measurement Results> In the corrosion resistance test, information INF was included in advance for the recording medium according to Example 1, and the recording medium was heated at a temperature of 60% ('C) and a relative humidity of 80%.
(%) under the same corrosion resistance test conditions as the comparative example.
The corrosion resistance I! is retained for 0 hours and then measured by measuring the damage rate (error rate) of the information described above and measuring the C/N ratio described above. was evaluated. As a result, the error rate was about 101, and the C/N
The ratio was 47.5 (dB), the same as the value before the corrosion resistance test. <Complex refractive index measuring element j@ and results> In this measurement, a separate sample was prepared with a protective film deposited to a thickness of 2000 (λ) on the surface of a silicon wafer under the same deposition conditions as above. The complex refractive index n-ki at a wavelength of 633 (nm) was measured using an ellipsometer. As a result, the complex refractive index was 2.22-0.02 i. Large 18 soup λ <Explanation of manufacturing conditions> In the recording medium according to the second embodiment, the protective films 13a and +3b are deposited and formed using the method according to the second invention, and the magnetic!
For the deposition of the film 15, samples were prepared using the same material, film thickness, and deposition conditions as described above. To explain in detail the conditions for depositing this protective film, first, a target for composition adjustment with a diameter of 126 (mm) made of titanium (Ti) and a film forming target with a diameter of 25 (mm) made of strontium titanate (SrTiO3) are used. Prepare a target. Thereafter, one surface of the above-mentioned target for composition adjustment was coated with six targets for film formation. In this way, on the surface to be sputtered, with the surface of the composition adjustment target covered by the film forming target, these two types of targets are simultaneously sputtered to form a protective film on the surface of the substrate 11 made of polycarbonate resin. 13a to about 800 (λ)
The film was deposited to a thickness of . The film forming conditions at this time were as described above, with an input power of 500 (W) and an argon gas pressure of 3 (mTorr). As can be understood from the above description, in Example 2, the ratio of the area of the film forming target made of SrTiO3 to the surface to be sputtered is approximately 95 (%), and the composition adjustment target made of Ti or the sputtered target is The protective film was formed with the area occupied by the surface being approximately 5 (%). <Explanation of C/N ratio measuring element j@ and measurement results> Even when the recording medium according to Example 2 was closed, the C/N ratio was measured under the same conditions as in Comparative Example and Example]. As a result, the C/N ratio of the recording medium according to Example 2 was 46.8 (dB). <Explanation of Corrosion Resistance Test Procedures and Measurement Results> The corrosion resistance test was also carried out after being held for 200 hours under the same corrosion resistance test conditions as in Comparative Example and Example 1, and the damage rate (error rate) of the information mentioned above was confirmed. Corrosion resistance was evaluated by the measurement and the measurement of the C/N ratio described above. As a result, the error rate was about 10-5, and C7
The N ratio was 46.8 (dB), the same as the value before the corrosion resistance test. <Measurement procedure and results of complex refractive index> In the complex refractive index measurement of the recording medium according to Example 2, a protective film with a film thickness of 2000 (A) was applied to the surface of the silicon wafer under the same deposition conditions as described above. A sample coated with was prepared separately, and the complex refractive index n-ki% at a wavelength of 633 (nm) was measured using an ellipsometer and a meter in the same manner as in Comparative Example and Example 1. As a result, the complex refractive index was 2.23-0.03 i. [Large] Explanation of manufacturing conditions> In the recording medium according to the third embodiment, titanium monoxide (Tie) is used as the target for composition adjustment, and the protective films 13a and 131 are formed by applying the method according to the first invention. ) and its adhesion,
For the deposition of the magnetic film 15, samples were prepared using the same material, film thickness, and deposition conditions as described above. In detail, the conditions for depositing this protective film are as follows: - a target for composition adjustment with a diameter of 126 (mm) made of titanium oxide (Tie) and strontium titanate (SrTiO3);
A film forming target with a diameter of 25 (mm) is prepared. Thereafter, as in Example 2, these two types of targets were simultaneously sputtered on the surface to be sputtered, with the surface of the composition adjustment target covered with six film forming targets. A protective film 13a with a thickness of about 800 (A) was deposited on the surface of the substrate 11 made of polycarbonate resin.The film forming conditions at this time were the same input power and argon gas pressure as described above. As can be understood from the above explanation, in this Example 3, the ratio of the area of the film forming target made of 5rTi(h) to the surface to be spun is approximately 95 (%), and the composition adjustment target made of TiO is The protective film was formed with a proportion of about 5 (%) on the above-mentioned surface. <Explanation of C/N ratio measurement procedure and measurement results> As a result of measuring the C/N ratio under the same conditions as Comparative Example, Example 1, and Example 2,
The C/N ratio of the recording medium according to Example 3 was 47.5 (dB)
Met. Explanation of the corrosion resistance test procedure and measurement results> Under the same corrosion resistance test conditions as the comparative example, Example 1, and Example 2 described above,
After holding the recording medium for 0 hours, the error rate and C/N ratio of the recording medium according to Example 3 were measured. It was 47.5 (dB), the same as the value before the test. Complex refractive index measurement procedure and results> In the measurement of the complex refractive index of the recording medium according to this Example 3, the same deposition conditions as above were applied to the surface of the silicon wafer.
A sample with a protective film of 2000 (A) was separately prepared and measured in the same manner as in Comparative Example, Example 1, and Example 2, and the complex refractive index was 2.22-0.02 i. . Large] External pressure <Explanation of manufacturing conditions> In the recording medium according to the fourth embodiment, titanium dioxide (Ti02) is used as the target for composition adjustment, and the protective films 13a and +3b are formed by applying the method according to the second invention. Adhesive formation,
For the deposition of the magnetic film 15, samples were prepared using the same material, film thickness, and deposition conditions as described above. In this protective film formation, titanium dioxide (TiO□)
The same power input and argon gas pressure as in Examples 2 and 3 were used, except that the target was used for composition adjustment. As can be understood from the above explanation, in this Example 4, the ratio of the area occupied by the film forming target made of SrTiO3 to the surface to be sputtered is approximately 95(%),
The protective film was formed by setting the ratio of the target for composition adjustment consisting of the above-mentioned surface to about 5 (%). <Explanation of C1N ratio measurement procedure and measurement results> This Example 4
As a result of measuring the C/N ratio under the same conditions as the comparative example and Examples 1 to 3, the C/N ratio of the recording medium according to Example 4 was 47.0 ( dB). Explanation of Corrosion Resistance Test Procedures and Measurement Results> After holding for 200 hours under the same corrosion resistance test conditions as in the comparative example and Examples 1 to 3, the error rate of the recording medium according to Example 4 was measured, and C/ As a result of measuring the N ratio, the error rate was about 10-5, and the C/N ratio was 47.0 (dB), the same as the value before the corrosion resistance test. Complex refractive index measurement procedure and results> In the complex refractive index measurement of the recording medium according to Example 4, the same deposition conditions as above were applied to the surface of the silicon wafer.
A sample with a protective film of 2000 (λ) was separately prepared and measured in the same manner as in Comparative Examples and Examples 1 to 3, and the complex refractive index was 2.21, which can be understood from this explanation. As shown, the extinction coefficient k of the recording medium according to Example 4 was O, and a substantially transparent protective film could be formed. Next, recording media according to Examples 5 to 8 in which barium titanate (8aTiO3) is used as a film formation target will be described. <Description of manufacturing conditions> In the recording medium according to Example 5, barium titanate (
A recording medium according to Example 5 was obtained by producing a recording medium under the same lamination relationship and film formation conditions as in Example 2, except for using a film formation target made of BaTiO3 with a diameter of 126 (mm). . <Explanation of C/N ratio measurement procedure and measurement results> In measuring the C/N ratio of the recording medium according to Example 5, the same recording medium as that of the comparative example and Examples 1 to 4 described above was used. As a result of measurement according to the procedure, C of the recording medium according to Example 5
/11 ratio was 48.0 (dB). Description of Corrosion Resistance Test Procedures and Measurement Results> After holding the recording medium according to Example 5 for 200 hours under the same corrosion resistance test conditions as the recording media according to Comparative Example and Examples 1 to 4. The corrosion resistance was evaluated by the error rate measurement described above and the C/N ratio measurement described above. As a result, the error rate is about 10-5, and C/
The N ratio was 48.0 (dB), the same as the value before the corrosion resistance test. Measurement procedure and results of complex refractive index> A sample according to Example 5 was separately prepared in which a protective film was deposited on the surface of a silicon wafer with a film thickness of 2000 (^) using the same deposition conditions as described above. As a result of measuring the complex refractive index n-ki@ using an ellipsometer, the complex refractive index was 2.
It was 25-0.02 i. In this Example 6, barium titanate (BaTiO3)
A recording medium was produced using the same lamination relationship and film forming conditions as in Example 2 using the second invention, except that a film forming target with a diameter of 25 (mm) consisting of was used. That is, with six of the above-mentioned film forming targets placed on the surface of a composition adjustment target made of titanium (Ti) and having a diameter of 126 mm, these two types of targets are simultaneously sputtered to form the protective film 13a. and +3bt were deposited. The film forming conditions at this time were the same input power and argon gas pressure as described above. As can be understood from the above explanation, in this Example 6, the ratio of the area occupied by the film forming target made of BaTiO3 to the surface to be sputtered is approximately 95 (%), and the ratio of the area occupied by the target for composition adjustment made of Ti to the sputtered surface is set. The protective film was formed with a proportion of about 5 (%) on the surface. <Explanation of C/N ratio measurement procedure and measurement results> This Example 6
(Comparative Examples and Examples 1 to 5
As a result of measuring the C/N ratio under the same conditions as above, the C/N ratio of the recording medium according to Example 6 was 47.0 (dB). Description of Corrosion Resistance Test Procedures and Measurement Results> After holding the recording medium according to Example 6 for 200 hours under the same corrosion resistance test conditions as the recording media according to Comparative Example and Examples 1 to 5. The corrosion resistance was evaluated by the error rate measurement described above and the C/N ratio measurement described above. As a result, the error rate is about 10-5, and C/
The N ratio was 47.0 (dB), the same as the value before the corrosion resistance test. Measurement procedure and results of complex refractive index A sample was separately prepared in which a protective film was deposited on the surface of a silicon wafer to a thickness of 2000 cm under the same deposition conditions as described above, and a comparative example and an example were prepared. As a result of measurement in the same manner as in 1 to 5, the complex refractive index was 2.27-0.02 i. The protective film was formed with the area occupied by the sputtered surface being approximately 5 (%). Taigo Ie L <Explanation of manufacturing conditions> In this Example 7, barium titanate (BaTiO3)
A recording medium was produced using the method according to the second invention under the same lamination relationship and film forming conditions as in Example 3, except that a film forming target with a diameter of 25 (mm) consisting of was used. - diameter 126 (m) of titanium oxide (Tie).
With six of the above film forming targets placed on the surface of the composition adjustment target (m), these two types of targets were simultaneously sputtered to form protective films 13a and +3b. The film forming conditions at this time were the same input power and argon gas pressure as described above. As can be understood from the explanation in 4 above, in this Example 7, the ratio of the area occupied by the film forming target made of BaTiOs to the surface to be sputtered is approximately 95 (%), and the composition adjustment target made of TiO is covered. <Explanation of C/N ratio measurement procedure and measurement results> Regarding the recording medium according to Example 7, the C/N ratio was also measured under the same conditions as the comparative example and Examples 1 to 6. C/ of the recording medium according to Example 7
The N ratio was 48.0 (dB). <Explanation of Corrosion Resistance Test Procedures and Measurement Results> The recording medium according to Example 7 was held for 200 hours under the same corrosion resistance test conditions as the recording media according to Comparative Example and Examples 1 to 6. Thereafter, the corrosion resistance was evaluated by the error rate measurement described above and the C/N ratio measurement described above. As a result, the error rate is about 10-5, and C/
The N ratio was 48.0 (dB), the same as the value before the corrosion resistance test. <Measurement procedure and results of complex refractive index> A sample was separately prepared with a protective film deposited on the surface of a silicon wafer at a film thickness of 2000 (λ) under the same deposition conditions as above, and measured using an ellipsometer. 633 (nm)
As a result of measuring the complex refractive index n-ki at the wavelength of , the complex refractive index was 2.25-0.02i. [Explanation of production conditions] In this Example 8, barium titanate (BaTiO3)
A recording medium was produced under the same conditions as in Example 4, except that the protective film 13a and +3El were formed using a film forming target with a diameter of 25 (mm) consisting of: That is, the above-mentioned film forming target was placed on the surface of a composition adjustment target made of titanium oxide (TiOz) with a diameter of 126 (mm).
A piece in! In this state, these 21M type targets were simultaneously sputtered to form protective films 13a and 13b. The film forming conditions at this time were the same input power and argon gas pressure as described above. As can be understood from the above explanation, in this Example 8, BaTi0. The ratio of the area occupied by the film forming target made of TiO on the surface to be sputtered is about 95 (%), and the ratio of the area occupied by the composition adjustment target made of TiO□ to the surface to be sputtered is about 5 (%). Adhesion formation was performed. <Explanation of C/N ratio measurement procedure and measurement results> Regarding the recording medium according to Example 8, the C/N ratio was measured under the same conditions as Comparative Example and Examples 1 to 7. Example 8
The C/N ratio of the recording medium was 47.5 (dB). <Explanation of Corrosion Resistance Test Procedures and Measurement Results> After being held for 200 hours under the same corrosion resistance test conditions as in the comparative example and Examples 1 to 7, the error rate of the recording medium according to Example 8 was measured, and the C/ As a result of measuring the N ratio, the error rate was about 10-', and the C/N ratio was 47.5 (dB), the same as the value before the corrosion resistance test. <Measurement procedure and results of complex refractive index> In the measurement of the complex refractive index of the recording medium according to Example 8, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 mm as described above. A sample was separately prepared and measured in the same manner as in Comparative Example and Examples 1 to 7, and as a result, the complex refractive index was 2.21. As can be understood from this explanation, the absorption coefficient k was O, similar to the recording medium according to Example 4 described above, and it was possible to realize a substantially transparent protective film. Next, Examples 9 to 1 in which a protective film was formed using both strontium titanate (SrTi03) and barium titanate (BaTiO3) as targets for film formation.
Let me explain about 2. In this Example 9, strontium titanate (SrTi
Conventional well-known sputtering was used, except that the protective films 13a and 13El were formed using a film-forming target with a diameter of 126 (mm) consisting of a mixed crystal of O3) and barium titanate (BaTiO3) (composition ratio 1:1). Example using technology]
A recording medium was produced using the same lamination relationship and film formation conditions as in Example 5. The film forming conditions at this time were the same input power and argon gas pressure as described above. <Explanation of C/N ratio measurement procedure and measurement results> This Example 9
The C/N ratio of the recording medium was measured under the same conditions as in Comparative Example and Examples 1 to 8, and the C/N ratio of the recording medium was 48.0 (dB). Note that a corrosion resistance test was not conducted on the magneto-optical recording medium according to Example 9. Complex refractive index measurement procedure and results> In the complex refractive index measurement of the recording medium according to Example 9, a protective film was applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 (λ) as described above. A sample was prepared separately and measured in the same manner as in Comparative Example and Examples 1 to 8, and as a result, the complex refractive index was 2,240.02i. <Explanation of manufacturing conditions> In this Example 10, strontium titanate (SrT
A film formation target with a diameter of 25 (mm) made of iO3) and a diameter 25 (mm) made of barium titanate (BaTiO3)
The recording medium was formed using the same lamination relationship and film forming conditions as in Example 3 and Example 7 using the second invention, except that the protective films 13a and +3b were formed using a film forming target of (mm). Created. F5, on the surface of a composition adjustment target made of titanium (Ti) with a diameter of 126 (mm), the above-mentioned Cugetto for film formation made of 5rTi03 and BaT were applied.
Three film-forming targets each made of iO3,
With a total of six targets loaded, these three types of targets were sputtered simultaneously to form protective films 13a and +3b. The film forming conditions at this time were the same input power and argon gas pressure as described above. As can be understood from the above description, in this Example 10, the total area ratio of the film forming target made of 5rTi03 and BaTi0+ on the sputtering target surface is approximately 95 (%), and the film forming target made of Ti The protective film was formed by setting the ratio of the area of the target for composition adjustment to the surface to be sputtered to about 5 (%). <Explanation of C/N ratio measurement procedure and measurement results> This Example 1
As a result of measuring the C/N ratio under the same conditions as Comparative Example and Examples 1 to 9, the C/N ratio of the recording medium was 47.0 (dB). Ta. Note that the magneto-optical recording medium according to Example 10 was not subjected to a corrosion resistance test as in Example 9 described above. <Measurement procedure and results of complex refractive index> In the complex refractive index measurement of the recording medium according to Example 10, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 (λ) as described above. A deposited sample was prepared separately and measured in the same manner as in Comparative Example and Examples 1 to 9, and the complex refractive index was 2.26-0.03 i. Explanation of Manufacturing Conditions In this Example 11, the same stacking relationship and film forming conditions as in Example 10 were used, except that a composition adjustment target made of -titanium oxide (Tie) was used. A recording medium was produced using the method according to the second invention.That is, a film forming target made of 5rTiOz and a film forming target made of 5rTiOz were placed on the surface of a composition adjustment target made of -titanium oxide (Tie) with a diameter of 126 (mm). These 3 were exposed to a film formation target made of BaTiO3, 3 each, for a total of 6 targets.
Various types of targets were simultaneously sputtered to form protective films 13a and +3b. The film forming conditions at this time were the same input power and argon gas pressure as described above. As can be understood from the above description, in this Example 11, the total area ratio of the film forming target made of SrTiO3 and BaTiO3 on the sputtering target surface is approximately 95 (%), and the film forming target made of TiO The protective film was formed by setting the ratio of the area of the target for composition adjustment to the surface to be sputtered to about 5 (%). <Explanation of C/N ratio measurement procedure and measurement results> This Example 1
Regarding the recording medium according to No. 1, Comparative Examples and Examples 1 to 10
As a result of measuring the C/N ratio under the same conditions as above, the C/N ratio of the recording medium was 48.0 (dB). <Explanation of corrosion resistance test procedure and measurement results> Example 11
Now, after holding for 1000 hours under the above-mentioned corrosion resistance test conditions, the error rate of the recording medium was measured and the C
/N ratio measurement, the error rate was approximately 10
-5, and the C/N ratio is 4, which is the same as the value before the corrosion resistance test.
It was 8.0 (dB). <Measurement procedure and results of complex refractive index> In the measurement of the complex refractive index of the recording medium according to Example 11, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 mm as described above. A deposited sample was prepared separately and measured in the same manner as in Comparative Example and Examples 1 to 10, and the complex refractive index was 2.24-0.02i. Explanation of manufacturing conditions> In this example 12, the same stacking relationship and film formation conditions as in the above example 11 were used, except that a composition adjustment target made of titanium dioxide (Ti02) was used. , a recording medium was produced using the method according to the second invention. That is, on the surface of a composition adjustment target made of titanium dioxide (TiO2) with a diameter of 126 (mm), a film formation target made of 5rTi(h) and a film formation target made of BaTiO3 were placed, 3 each, for a total of 6 These three types of targets are sputtered at the same time in the state where the protective film 13 is exposed.
a and +3b% formed. The film forming conditions at this time were the same input power and argon gas pressure as described above. As can be understood from the above description, in this Example 12, the total area ratio of the film forming target made of 5rTi(h) and BaTiOs on the surface to be sputtered is approximately 95 (%), The proportion of the area occupied by the target for composition adjustment made of TiO□ on the surface to be sputtered is approximately 5 (%).
As a step, a protective film was formed. <Explanation of C/N ratio measurement procedure and measurement results> This Example 1
Comparative Examples and Examples 1 to 11 regarding the recording medium according to 2.
As a result of measuring the C/N ratio under the same conditions as above, the C/N ratio of the recording medium was 48.2 (dB). <Explanation of corrosion resistance test procedure and measurement results> Example 12
Now, as in Example 11, after holding for 1000 hours under the above-mentioned corrosion resistance test conditions, the error rate of the recording medium was measured and the C/N ratio was measured. As a result, the error rate was The C/N ratio was about 10-5, and the C/N ratio was 48.2 (dB), the same as the value before the corrosion resistance test. <Measurement procedure and results of complex refractive index> In the complex refractive index measurement of the recording medium according to Example 12, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 (λ) as described above. A sample was separately prepared and measured in the same manner as in Comparative Example and Examples 1 to 11, and as a result, the complex refractive index was 2.22. As can be understood from this explanation, the absorption coefficient k was 0, similar to the recording media according to Examples 4 and 8 described above, and a substantially transparent protective film could be realized. Hereinafter, the characteristics of the comparative example and the characteristics of Examples 1 to 12 described above will be discussed in detail with reference to the attached table. First, if we compare the C/N ratio, as can be understood from this appendix and the above explanation, the recording medium according to the comparative example has a C/N ratio of 44.0 (dB), whereas the recording medium according to Examples 1 to 12 has a C/N ratio of 44.0 (dB).
An improvement in C/N ratio characteristics is observed in any of the recording media according to the above. - As an example, in Example 2, which had the lowest improvement in C/N ratio among these Examples, 46.8 (dB) was obtained, which was an improvement of 2.8 (dB). In addition, in the recording medium according to Example 12, the improvement in the characteristic value was most remarkable, with a C/N of 48.2 (dB), which is 4.2 (dB) higher than that of the comparative example.
The ratio was obtained. In general, as can be understood from the results of the corrosion resistance test, Comparative Examples, Examples 1 to 8, Example 11, and Example 1
In the recording medium according to Example 2, no decrease in the C/N ratio was observed after the 200-hour corrosion resistance test, and in particular, the recording medium according to Example 11 and the recording medium according to Example 12 had the same corrosion resistance. Even after maintaining the test conditions for 1000 hours, no decrease in the C/N ratio was observed. On the other hand, as already mentioned, from the measurement of the error rate,
The recording medium according to the comparative example, which was maintained under the above-mentioned corrosion resistance test conditions for 200 hours, had a resistance of about 10-4. In contrast, Examples 1 to 8, Example 11, and Example 1
In the recording medium according to No. 2, under the same conditions as the comparative example, about 10-
A value of about 5 was obtained, and it can be understood that the stability of the recording medium was improved by the material composition of the protective film according to the present invention. Roughly speaking, the same corrosion resistance test conditions as above were applied to the recording medium according to Example 11 and the recording medium according to Example 12.
An error rate of about 10-5 was obtained even after holding for a long time, and the stability of recorded information was improved by providing a protective film obtained by simultaneously sputtering both 5rTi03 and BaTiO3. It can be seen that the results are significantly improved. Moreover, if we compare the refractive index n of the complex refractive index n-ki, the refractive index n of the sample according to the comparative example is 1.90, whereas the refractive index n of the sample according to Examples 1 to 12 is The refractive index n was also 2.21 or more in Example 1, and it can be seen that the C/N ratio was improved by Kerr effect enhancement. Furthermore, regarding the extinction coefficient k, compared to the extinction coefficient k of 0.10 in the comparative example, a remarkable improvement was observed in all Examples, especially in Examples 4, 8, and 12. In the sample according to the above, the extinction coefficient k becomes 0, and it can be understood that a substantially transparent protective film material is applied. In addition, as can be understood from the attached table (for example, when comparing the three types of recording media according to Examples 2 to 4, as the proportion of oxygen contained in the target for composition adjustment increases, the extinction coefficient decreases. It can be seen that there is a tendency for the value of From the comparison of the respective recording media in Example 6 or Example 9 and Example 10, it was found that by using the method according to the second invention and using % titanium (Ti) in the target for composition adjustment, the refractive index n was improved. As can be understood from the comparison between the above-mentioned comparative example and Examples 1 to 12, in the recording medium manufactured by the method according to the second invention of this application, the composition of each material is different. By sputtering the film-forming target at the same time as the adjustment target, a recording medium with superior characteristics compared to conventional recording media can be obtained. Diameter 126 made of SrTi03)
A recording medium was produced using a film formation target of (mm) under the same layer closure and film formation conditions as in Example 1. The film forming conditions at this time were the same input power as described above, and the gas pressure of the mixed atmosphere described above was 3 (mTorr). Next, as an example of the method according to the third invention of this application,
Example 13 in which a protective film was formed by sputtering only the layering target in a mixed atmosphere of inert gas and oxygen
~A recording medium according to Example 15 will be explained. In addition, in these Examples according to the third invention, the corrosion resistance test was not conducted as in Examples 9 and 10 described above. Fire ■ (Explanation of manufacturing conditions) In this Example 13, sputtering was performed in a mixed atmosphere of 80% by volume of argon and 20% by volume of oxygen to achieve <C/
Explanation of N ratio measurement procedure and measurement results> As a result of measuring the C/N ratio on the recording medium according to Example 13 under the same conditions as Comparative Example and Examples 1 to 12, the recording medium C of
/N ratio was 47.6 (dB). <Measurement procedure and results of complex refractive index> In the complex refractive index measurement of the recording medium according to Example 13, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 (λ) as described above. A sample was separately prepared and measured in the same manner as in Comparative Example and Examples 1 to 12, and as a result, the complex refractive index was 2.22. As can be understood from this explanation, the absorption coefficient k was 0, similar to the recording media according to Examples 4, 8, and 12 described above, and a substantially transparent protective film could be realized. . Taiyu U <Description of manufacturing conditions> In this Example 14, the protective film 1 was sputtered in a mixed atmosphere of 80% by volume of argon and 20% by volume of oxygen.
A recording medium was produced under the same lamination relationship and film forming conditions as in Example 5 using a film forming target made of barium titanate (BaTiO3) with a diameter of 126 (mm), except that 3a and +3b@ were formed. The film forming conditions at this time were the same input power as described above, and the gas pressure of the mixed atmosphere described above was 3 (mTorr). <Explanation of C/N ratio measurement procedure and measurement results> Regarding the recording medium according to Example 14, Comparative Example and Examples 1 to 1
As a result of measuring the C/N ratio under the same conditions as in Example 3, the C/N ratio of the recording medium was 47.5 (dB). <Measurement procedure and results of complex refractive index> In the complex refractive index measurement of the recording medium according to Example 14, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 (λ) as described above. A sample was separately prepared and measured in the same manner as in Comparative Example and Examples 1 to 13, and as a result, the complex refractive index was 2.21. As can be understood from this explanation, the absorption coefficient k is 0, similar to the recording media according to Examples 4, 8, 12, and 13 described above, and a substantially transparent protective film is realized. I was able to do that. <Explanation of manufacturing conditions> In Example 15, the protective film 1 was sputtered in a mixed atmosphere of 80% by volume of argon and 20% by volume of oxygen.
Strontium titanate (SrTiO3) and barium titanate (BaT
Diameter 126 consisting of a mixed crystal of iO3) and (composition ratio 1:1)
A recording medium was produced under the same lamination relationship and film forming conditions as in Example 9 using a film forming target of (mm). The film forming conditions at this time were the same input power as described above, and the gas pressure of the mixed atmosphere described above was 3 (mTorr). <Explanation of C/N ratio measurement procedure and measurement results> This Example 1
Regarding the recording medium according to No. 5, Comparative Examples and Examples 1 to 14
As a result of measuring the C/N ratio under the same conditions as above, the C/N ratio of the recording medium was 48.1 (dB). Similar to the recording media according to Examples 4, 8, and 12 to 14, the extinction coefficient kfJ<o, and a substantially transparent protective film could be realized. As can be understood from the characteristics of the recording media according to Examples 13 to 15, according to the method of the third invention according to this application, a protective film is formed by sputtering in a mixed atmosphere of inert gas and oxygen. By doing so, it is possible to obtain a complex refractive index that is almost the same as when titanium dioxide (TiO7) is used as a target for composition adjustment using the second invention of this application, and it is possible to form a substantially transparent protective film. . <Measurement procedure and results of complex refractive index> In the measurement of the complex refractive index of the recording medium according to Example 15, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 mm as described above. A deposited sample was prepared separately and measured in the same manner as in Comparative Example and Examples 1 to 14, and as a result, the complex refractive index was 2.23. As can be understood from this explanation, as described above, as an example of the method according to the fourth invention of this application, a film forming target and a composition adjusting target were prepared in a mixed atmosphere of an inert gas and oxygen. Example 1 in which a protective film was formed by simultaneously sputtering
Recording media according to Examples 6 to 18 will be explained. As mentioned above, as can be understood from the embodiments of the second invention, titanium (T
When a protective film was formed using i), an improvement in the refractive index was observed. Therefore, in this example, 1 is used as a target for composition adjustment, and in order to facilitate comparison with the example according to the third invention, the mixed atmosphere is argon 8.
Characteristic measurements were performed for the cases of 0 (vol%) and 20 (vol%) of oxygen. Medical Director (Explanation of Manufacturing Conditions) In this Example 16, the protective film 1 was sputtered in a mixed atmosphere of 80% by volume of argon and 20% by volume of oxygen.
A recording medium was produced using the same lamination relationship and film forming conditions as in Example 2, except that 3a and +3b were formed. That is,
A composition adjustment target made of titanium (Ti) with a diameter of +26 (mm) and strontium titanate (SrTi0
Prepare a film forming target with a diameter of 25 (mm) consisting of 3), cut six film forming targets on the surface of the composition adjustment target described above, and in the mixed atmosphere described above,
These two types of targets are sputtered simultaneously. The film forming conditions at this time were the same input power as described above, and the gas pressure of the mixed atmosphere described above was 3 (mTorr). <Explanation of C/N ratio measurement procedure and measurement results> Comparative example and Examples 1 to 1
As a result of measuring the C/N ratio under the same conditions as in No. 5, the C/N ratio of the recording medium was 47.5 (dB). <Explanation of corrosion resistance test procedure and measurement results> This Example 16
Then, as in Comparative Examples and Examples 1 to 8, after holding for 200 hours under the above-mentioned corrosion resistance test conditions, the error rate and C/N ratio of the recording medium were measured. . As a result, the error rate is about 10-5, and C/
The N ratio was 47.5 (dB), the same as the value before the corrosion resistance test. Complex refractive index measurement procedure and results> In the complex refractive index measurement of the recording medium according to Example 16, a protective film was also applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 mm as described above. A sample was prepared separately and measured in the same manner as in Comparative Example and Examples 1 to 15, and as a result, the complex refractive index was 2.23. As can be understood from this explanation, the absorption coefficient k is O, similar to the recording media according to Examples 4, 8, and 12 to 15 described above, and a substantially transparent protective film is realized. I was able to do that. Top I drawer <Description of manufacturing conditions> In this Example 17, the protective film 1 was sputtered in a mixed atmosphere of 80% by volume of argon and 20% by volume of oxygen.
A recording medium was manufactured using the same lamination relationship and film forming conditions as in Example 6, except that 3a and +3b were formed. That is,
A composition adjustment target with a diameter of 126 (mm) made of titanium (Ti) and a film formation target with a diameter of 25 (mm) made of barium titanate (BaTiO3) were prepared, and the surface of the composition adjustment target described above was prepared. Six film-forming targets are installed in the apparatus, and these two types of targets are sputtered simultaneously in the above-mentioned mixed atmosphere. The film forming conditions at this time were the same input power as described above, and the gas pressure of the mixed atmosphere described above was 3 (mTorr). <Explanation of C/N ratio measurement procedure and measurement results> Regarding the recording medium according to Example 17, Comparative Example and Examples 1 to 1
As a result of measuring the C/N ratio under the same conditions as in Example 6, the C/N ratio of the recording medium was 47.0 (dB). Explanation of corrosion resistance test procedure and measurement results> Example 17
Now, as in Comparative Examples and Examples 1 to 8, after holding for 200 hours under the above-mentioned corrosion resistance test conditions, the error rate and C/N ratio of the recording medium were measured. Ta. As a result, the error rate is about 10-5, and C/
The N ratio was 47°0 (dB), the same as the value before the corrosion resistance test. Complex refractive index measurement procedure and results> In the complex refractive index measurement of the recording medium according to Example 17, a protective film was applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 (λ) as described above. A discolored sample was prepared separately and measured in the same manner as in Comparative Examples and Examples 1 to 16, and as a result, the complex refractive index was 2.25. As can be understood from this explanation, the absorption coefficient k is O, similar to the recording media according to Examples 4, 8, and 12 to 16 described above, and a substantially transparent protective film is realized. I was able to do that. In Example 18, the protective film +
A recording medium was manufactured using the same lamination relationship and film forming conditions as in Example 10, except that 3a and +3b were formed. That is, strontium titanate (S
Three film-forming targets with a diameter of 25 (mm) made of Ti03) and three film-forming targets with a diameter of 25 (mm) made of barium titanate (BaTiO3) were placed in the above-mentioned mixed atmosphere. , these three types of targets are sputtered simultaneously. The film forming conditions at this time were the same input power as described above, and the gas pressure of the mixed atmosphere described above was 3 (mTorr). <Explanation of C/N ratio measurement procedure and measurement results> This Example 1
Regarding the recording medium according to No. 8, Comparative Examples and Examples 1 to 17
As a result of measuring the C/N ratio under the same conditions as above, the C/N ratio of the recording medium was 47.9 (dB). Note that a corrosion resistance test was not conducted on the recording medium according to Example 18. Complex refractive index measurement procedure and results> In the complex refractive index measurement of the recording medium according to Example 18, a protective film was applied to the surface of the silicon wafer under the same deposition conditions and film thickness of 2000 (λ) as described above. A sample coated with was prepared separately and measured in the same manner as in Comparative Example and Examples 1 to 17, and as a result, the complex refractive index was 2.24. As can be understood from this explanation, the absorption coefficient kfJ<O, similar to the recording media according to Examples 4, 8, and 12 to 17 described above, and a substantially transparent protective film is realized. I was able to do that. Hereinafter, with reference to the drawings, as an example according to the fourth invention of this application, various oxygen contents in the mixed atmosphere of inert gas and oxygen (with various oxygen contents) will be described. The following describes the results of measuring the complex refractive index of the sample obtained by sputtering the target at the same time. A sample was used in which a protective film material was deposited on the surface of the wafer to a thickness of 2000 (A).To explain the manufacturing conditions for this sample in detail, first, the same conditions as those used in Example 2 described above were used. A film forming target made of strontium titanate (SrTiO3) and a composition adjustment target made of titanium (Ti) are prepared, which have the same dimensions.After that, oxygen is removed in a gas containing argon and oxygen. The composition adjustment target described above and the 2f! type film formation target were simultaneously sputtered to form a film in such a deposition atmosphere by varying the ratio within the range of 0 to 50 (volume %). The deposition conditions at this time were that the input power was 500 (W), and the pressure of Suba-Ntagas consisting of the above-mentioned mixed gas was 3 (
mTorr). FIGS. 1 and 2 are characteristic curve diagrams showing the results of measuring the complex refractive index n-ki for each sample produced under the above manufacturing conditions. In these figures, Figure 1 is
The vertical axis shows the refractive index n and the horizontal axis shows the oxygen content (volume %) 8. In FIG. 2, the vertical axis shows the extinction coefficient k and the horizontal axis shows the oxygen content (volume %). First, as can be understood from FIG. 1, as the oxygen content in the sputtering gas was increased, the refractive index n tended to decrease. For example, if Suba Ntagas is oxygenated 0 (vol%) (
In the case of the above-mentioned Example 21 in which argon was 100% (by volume), the refractive index n was 2.23, whereas oxygen was 5%.
When it was set to 0 (volume %), the refractive index n decreased to about 2.1. Furthermore, as can be understood from Fig. 2, a similar tendency is observed for the extinction coefficient k, and in the sample corresponding to Example 2 where the oxygen content in the sputtering gas is 0 (vol%), the extinction coefficient It became 0.03. On the other hand, when sputtering is performed in a mixed atmosphere with an oxygen content of 20 (vol%), it is observed that the extinction coefficient k becomes O; Even as a value, it was observed that it showed O. Next, we will explain the results of measuring the complex refractive index of samples obtained by using barium titanate as a film formation target instead of the strontium titanate mentioned above and changing the content of argon and oxygen to a minimum. do. The various conditions related to sample preparation are as follows: strontium titanate (
Barium titanate (BaTi) is used instead of SrTi03).
Measurements were performed using a sample prepared by depositing a protective film material with a film thickness of 2000 (λ) on the surface of a silicon wafer, except that O3)7& was used. 3 and 4 are characteristic curve diagrams showing the results of measuring the complex refractive index n-ki in the same manner as in FIG. 1 or 2 described above. In these figures, the third diagram shows the refractive index n on the vertical axis and the oxygen content (volume %) on the horizontal axis.
In the figure, the vertical axis shows the extinction coefficient k and the horizontal axis shows the oxygen content (volume %).
This is shown by taking the following. First, as can be understood from Figure 3, even in the sample deposited using this barium titanate in a mixed atmosphere, the oxygen content in the sputtering gas is increased, as in the case of strontium titanate described above. According to
A decreasing trend in the refractive index n was observed. For example, when the sputtering gas is oxygen O (volume %) (corresponding to the above-mentioned Example 6 where argon is 100 (vol%)), the refractive index n is 2.
It became 27. On the other hand, when the oxygen content in the sputtering gas was set to 50 (vol%), the refractive index n decreased to about 2.1. Furthermore, as can be understood from Fig. 4, the same tendency as that of strontium titanate was observed in the extinction coefficient k, and the sample in which the oxygen content in Suba Shita Gas was O (volume %) (corresponding to Example 6) was observed. ), the extinction coefficient k was 0.02. On the other hand, when sputtering is performed in a mixed atmosphere with an oxygen content of 20 (vol%), it is observed that the extinction coefficient k becomes 0, as in the case of strontium titanate, and the It can be understood that even if the ratio is larger than 20 (volume %), it becomes O. As mentioned above, regarding the embodiments of the invention of this application, f! A detailed explanation was given using recording media produced under various conditions as samples. Here, the relationship between the above-described manufacturing methods and the composition of the protective film manufactured by each manufacturing method will be explained. Among the above-mentioned examples, the recording media according to Example], Example 5, and Example 9 were manufactured by depositing and forming a protective film using a conventionally well-known sputtering technique. Also,
In addition, as can be understood from the results of characteristic measurements, the recording media (protective films) according to Examples 1 to 18 had almost the same composition even in the recording media produced by the method invention of this application. It is considered to have. In these elemental compositions, for example, metal elements such as strontium, barium, and titanium can be determined using chemical analysis techniques that utilize the Auger effect, but in the case of titanic acid compounds, gaseous components and Since it contains oxygen, which is easily formed, it is difficult to determine the exact composition. However, as can be understood from, for example, the literature ■: "Dielectric Part" (written by Koten Oka, pp. 55-77, published by Gendai Kogakusha), for example, MTi
For a titanate-based substance represented by Gx (M is a metal element), it can be determined by averaging the complex refractive index of MO and the complex refractive index of TiOx-+. Briefly speaking, it is known that in the titanic acid-based substances mentioned above, the closer the value of X is to 3, the closer the extinction coefficient is to k or O. To explain in detail: -Titanium oxide (Tie)
While the titanate obtained from the metal oxide MO and the above-mentioned metal oxide MO has absorption (the extinction coefficient k is not 0),
It is known that titanates obtained from titanium dioxide (Ti02) and metal oxides are transparent (extinction coefficient k is 0). If the composition of the protective films according to Examples 1 to 18 described above is calculated from such optical properties, the value of X described above is 2.
7≦×≦3.0. Although the embodiments of the present invention have been described in detail above, it is clear that the present invention is not limited only to the embodiments described above. For example, in the above-mentioned embodiment, the case where argon was used as the sputtering residue according to the method invention of this application was explained, but the same effect can be expected even if other inert gases are used. Further, as an example of the structure of the recording medium according to the embodiment, one constructed with interlayers shown in FIG. 5 is illustrated. however,
The magneto-optical recording medium of the present invention can obtain the same effect not only by a specific lamination relationship, but also by adding, for example, a reflective film or other constituent components. . Roughly speaking, in the above-mentioned embodiments, the case where a magnetic film made of Tb-Fe-Co was used was explained, but the present invention is not limited to this, and various RE-TM gold alloys can be used. These materials, dimensions, MS distribution, numerical conditions and others,
It will be appreciated that the specific conditions described above may be subject to any suitable design modifications and variations within the scope of the invention. (Effect of the invention) As is clear from the above explanation, according to the magneto-optical recording medium according to the first invention of this application, as a protective film material,
Strontium titanate compounds (SrTiOx) and barium titanate compounds (8aTiOx) (however, X
represents a value of 2.7≦X≦3,0), or a mixed crystal of both substances is used as a protective film. Therefore, compared to recording media provided with conventional protective film materials, it is possible to achieve a higher refractive index and a lower extinction coefficient, and there is no significant deterioration in corrosion resistance. In addition, a method for manufacturing a magneto-optical recording medium according to a second invention of this application (according to which a protective film is formed by simultaneously sputtering a film forming target and a composition adjustment target made of the above-mentioned predetermined materials). By doing so, it is possible to easily realize the recording medium r8 according to the first invention.Roughly speaking, according to the method for manufacturing a magneto-optical recording medium according to the third invention of this application, the above-mentioned process is performed in a mixed atmosphere containing oxygen. The recording medium according to the first invention can be easily obtained by forming a protective film by sputtering a film-forming target made of a predetermined material. According to the method for manufacturing a magneto-optical recording medium, the recording medium according to the first invention can be easily obtained by simultaneously applying the second invention and the third invention described above.Therefore, the invention according to this application By applying

[Brief explanation of the drawing]

1 and 3 are characteristic curve diagrams in which the vertical axis shows the refractive index n and the horizontal axis shows the oxygen content in the sputtering atmosphere, respectively, in order to explain the embodiment. In order to explain the examples, a characteristic curve diagram showing the extinction coefficient k on the vertical axis and the oxygen content in the sputtering atmosphere on the horizontal axis, respectively. FIG. 2 is an explanatory diagram schematically showing a configuration example of a magneto-optical recording medium in cross section. 11...Substrate, 13a, 13b...Protective film 1
5... Magnetic film, 17... Magneto-optical recording medium. Patent Applicant Oki Electric Industry Co., Ltd.Oxygen Content Rate (Volume %)Explanatory Diagram of ExamplesOxygen Content Rate (Volume %)Explanatory Diagram of ExamplesFigure 4Oxygen Content Rate (Volume %)Oxygen Content Rate (Volume %) Implementation An explanatory diagram of an example Fig. 2 An explanatory diagram of a conventional technique and an example Fig. 5

Claims (4)

[Claims] (1) In a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate, the protective film is made of a strontium titanate compound (SrTiO_x) and a barium titanate compound (BaTiO_x) (however, X is 2.7≦X≦3.0
represents the value of ) or a mixed crystal of both materials. (2) When manufacturing a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate, the protective film is replaced with strontium titanate (SrTiO_3) and barium titanate (BaTiO_3).
A film formation target made of one or both selected from _3) and a composition adjustment target made of titanium (Ti) or titanium oxide (TiO_Y) (wherein, Y represents a positive number). 1. A method for manufacturing a magneto-optical recording medium, characterized in that deposition is formed by sputtering at the same time. (3) When manufacturing a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate, the protective film may be formed of strontium titanate (SrTiO_3) and barium titanate (BaTiO).
_3) A method for manufacturing a magneto-optical recording medium, characterized by sputtering and depositing a film-forming target made of one or both of the above in a mixed atmosphere of inert gas and oxygen. . (4) When manufacturing a magneto-optical recording medium comprising at least a protective film and a magnetic film on a substrate, the protective film may be formed of strontium titanate (SrTiO_3) and barium titanate (BaTiO).
A film formation target made of one or both selected from _3) and a composition adjustment target made of titanium (Ti) or titanium oxide (TiO_Y) (wherein, Y represents a positive number). A method for manufacturing a magneto-optical recording medium, characterized in that deposition is performed by sputtering simultaneously in a mixed atmosphere of an inert gas and oxygen.