JP2742089B2 - Magneto-optical recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a magneto-optical recording medium, and more particularly, to a reflective film having an excellent CN ratio (Carrier Noise Ratio) and recording sensitivity. The present invention relates to a magneto-optical recording medium provided.

(Prior Art) Magneto-optical recording media (hereinafter sometimes simply referred to as recording media) are being actively researched and developed as high-density recording media having a rewritable magnetic film.

Among the magneto-optical recording materials constituting the magnetic film of such a recording medium, the magnetization direction of an amorphous alloy of a rare earth metal and a transition metal (hereinafter may be simply referred to as an RE-TM alloy) is also known. Being a perpendicular magnetization film oriented perpendicular to the film-forming surface, having a large coercive force (KOe), and being relatively easy to form by sputtering, vacuum deposition or other deposition techniques In this respect, research is progressing most and practical application is progressing.

In a recording medium using such an RE-TM alloy, an extremely high-density recording of 10 ⁸ (bits / cm ² ) is possible because the magnetic film is a perpendicular magnetization film. It has an excellent feature that information erasing and rewriting can be repeated almost infinitely.

However, the magnetic film made of the RE-TM alloy has low corrosion resistance (for example, see Reference I: “Magneto-optical disk” (supervised by Shutake Imamura, published by Trikeps Co., Ltd., p. 427)). (Kerr effect) is small.

Therefore, by providing a reflective film at a position opposite to the reading side of the magnetic film described above, or by arranging the magnetic film with a protective film sandwiching the magnetic film, the apparent Kerr ( Kerr) A structure for increasing the rotation angle is known (the aforementioned document I: p. 119).

Hereinafter, the above-described conventional magneto-optical recording medium will be described with reference to the drawings.

FIG. 5 (A) is an explanatory diagram schematically showing a cross section for explaining one configuration example of a conventional recording medium. In the figure, hatching indicating a cross section is partially omitted.

As shown in FIG. 5A, a recording medium 19 is formed by sequentially forming a protective film 13a, a magnetic film 15, a protective film 13b, and a reflective film 17 on the surface of the substrate 11.

Among them, the substrate 11 is made of a material that is transparent at the wavelength of light used for writing and reading on the recording medium, such as polycarbonate resin, glass, and epoxy resin.

Further, the protective films 13a and 13b are, for example, SiO, SiO ₂ , AlN,
It is formed by applying a protective film material such as Si ₃ N ₄ , AlSiN, or AlSiON.

Further, the magnetic film 15 is composed of the above-described RE-TM alloy, and examples of such an alloy include a Tb-Fe alloy, a Tb-Co alloy, a Tb-Fe-Co alloy, or a combination of a rare earth metal and a transition metal. Are variously known.

In addition, as a material forming the reflective film 17, a reflective film material such as aluminum (Al), gold (Au), silver (Ag), copper (Cu), or titanium (Ti) is known.

In addition, as a recording medium including the above-described reflective film 17, a protective film 13a, a magnetic film 15, a reflective film 1
7 and the protective film 13b are sequentially laminated on the recording medium 21 (fifth
FIG. (B) is also known.

Such a recording medium is irradiated with a laser beam having a spot diameter of about 1 (μm) in a direction from the substrate 11 to the magnetic film 15 in a state where an external magnetic field is applied. Is written. That is, the coercive force of the magnetic film locally heated by the above-described laser beam is reduced, and at this time, information is written to the magnetic film by an external magnetic field that carries recorded information. Further, such recording information is written by the pit length and interval of the laser beam described above.

As can be understood from the above description, the recording sensitivity of the magneto-optical recording medium is greatly affected by the heat retention for the magnetic film and the degree of multiple reflection.

Therefore, when looking at the reflective film from such a viewpoint, while suppressing the heat radiation during writing by forming the reflective film with a material having a small thermal conductivity, configuring the film with a material having a high reflectance,
Efficient multiple reflection at the time of reading is required.

(Problems to be Solved by the Invention) As described above, among the conventionally known reflective film materials, when a reflective film is formed using silver (Ag), Ag has a high reflectance, A CN ratio of about 48 (dB) can be achieved. However, on the other hand, since the thermal conductivity is large, it is necessary to increase the recording power corresponding to the output of the laser beam used for writing in order to compensate for the heat radiation of the magnetic film.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magneto-optical recording medium that can be written with a smaller recording power than a case where a reflective film is composed of silver alone and has practical read sensitivity in view of the above-described conventional problems. It is in providing.

(Means for Solving the Problems) In order to achieve the object of the present invention, according to the first invention of the present application, in a magneto-optical recording medium comprising at least a magnetic film and a reflective film on a substrate, a reflective film Consists of silver (Ag) and manganese (Mn), and the addition rate of manganese (Mn) is 2
(Atomic%) or more and 32 (atomic%) or less.

According to the second invention, in a magneto-optical recording medium comprising at least a magnetic film and a reflective film on a substrate, the reflective film is formed of silver (Ag), manganese (Mn), and tin (Sn).
And the addition rate of silver (Ag) is 71 (at.%) Or more.
(Atomic%) or less, the addition ratio of manganese (Mn) is 1 (at.%) To 15 (at.%), And the addition ratio of tin (Sn) is 1 (at.%) To 23 (at.%).

In carrying out the second invention, the composition of the above-mentioned reflective film composed of silver (Ag) -manganese (Mn) -tin (Sn) is changed to manganese (Mn) in silver (Ag) -manganese (Mn) -tin (Sn). ) Is 1 (at.%), And the addition ratio of tin (Sn) is 1 (at.%) Or more and 23 (at.%) Or less. Manganese in silver (Ag) -manganese (Mn) -tin (Sn) Mn) is 7 (at.%) And tin (Sn) is 1 (at.%) Or more and 20 (at.%) Or less. Manganese in silver (Ag) -manganese (Mn) -tin (Sn) It is preferable that the addition rate of (Mn) is 15 (atomic%) and the addition rate of tin (Sn) is in the range of 1 (at.%) To 14 (at.%).

(Operation) According to the magneto-optical recording medium of the first invention of this application,
A reflection film is composed of silver (Ag), which can have a high CN ratio, and manganese (Mn). For this reason, by employing a configuration including Mn, it is possible to reduce the recording power as compared with a reflective film composed of Ag alone.

According to the magneto-optical recording medium of the second invention of this application, silver (Ag), which can have a high CN ratio, and manganese (Mn)
The reflection film is constituted by a combination of tin and tin (Sn). For this reason, by employing a configuration including Mn and Sn, it is possible to reduce the recording power as compared with a reflective film composed of Ag alone.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. It should be noted that the following embodiments will be described with preferred numerical examples and other conditions within the scope of the present invention, but these are merely examples, and the present invention is not limited only to these conditions. I want to be understood.

Hereinafter, the case where a reflective film is formed by silver (Ag) and manganese (Mn) according to the first invention is referred to as Example 1, and silver (Ag), manganese (Mn), and tin (Sn) according to the second invention are used. Embodiment 2 describes a case where a reflection film is formed by using this embodiment.

Example 1 First, in Example 1, silver (Ag) and manganese (Mn) were used.
The recording power and the CN ratio were measured for a plurality of magneto-optical recording media on which reflective films having different thicknesses were formed by changing the addition ratio of Mn in the reflective film composed of the above.

<Production of Magneto-Optical Recording Medium> First, a procedure for producing a magneto-optical recording medium as a measurement sample will be described with reference to the drawings.

In this embodiment, a recording medium is manufactured with the configuration shown in FIG. 5B, and a protective film 13a, a magnetic film 15, a reflective film 17, and a protective film 13b are sequentially laminated on the surface of the substrate 11, A magneto-optical recording medium 21 serving as a measurement sample was obtained.

First, a protective film 13a made of silicon aluminum nitride (AlSiN) having a thickness of 700 (Å) is applied to the surface of a substrate 11 made of polycarbonate. This deposition is performed by a magnetron sputtering method.
0 (W) and the gas pressure of argon was 3 (mTorr).

Subsequently, according to the above-described deposition method and deposition conditions, a target having a composition of terbium: iron: cobalt having a ratio of the number of atoms of 22: 70: 8 was used, and about 300 μm was formed on the surface of the protective film 13a.
The magnetic film 15 is deposited with a thickness of (Å).

Next, on the surface of the above-mentioned protective film 13b, the addition ratio of Mn in Ag and Mn is variously changed within a range of 0 to 45 (atomic%), and further, the film thickness is set to 200 (Å) and 300 (Å). ) And 400
As (Å), a reflective film 17 having a different Mn addition rate and a different film thickness is used.
Each is formed by adhesion.

At this time, the deposition condition is 500
(W), the argon gas pressure was 3 (mTorr), and the above-mentioned Mn addition rate was variously changed by changing the area ratio on the surface to be sputtered when the targets made of each single metal were overlapped. .

Thereafter, the protective film 1 made of AlSiN is formed on the surface of the above-described reflective film 17 under the same deposition conditions and film thickness as the protective film 13a.
3b was applied, and a plurality of magneto-optical recording media 21 having different compositions of the reflective film 17 were obtained as measurement samples.

<Procedure for Characteristic Measurement> Next, a procedure for measuring the recording power and the CN ratio of the recording medium as the above-described measurement sample will be described.

First, when measuring the recording power of each sample, the wavelength 83
Using 0 (nm) light, the recording was performed under the same recording conditions of a rotation speed of 1800 (rpm), a duty of 33 (%), and a recording frequency of 3.7 (MHz).

The measurement of the CN ratio was performed under the above-described conditions with writing at a recording power corresponding to each sample, and then at a reading power of 1.0 (m
W), and the readout condition was 30 band (KHz).

<Results of Characteristic Measurement> Next, with reference to the drawings, the relationship between the above-described measurement results of the recording power and the CN ratio and the addition ratio of Mn in Ag-Mn will be described.

FIG. 1 shows the recording power (mW) on the vertical axis and Ag- on the horizontal axis to explain the relationship between the above-mentioned addition rate and recording power.
FIG. 3 is a characteristic curve diagram showing the addition ratio (atomic%) of Mn. In the figure, curve a is the result of the sample provided with a reflective film with a film thickness of 400 (Å), curve b is the result of the sample provided with a reflective film with a film thickness of 300 (Å), and curve c is the film thickness 20
The results of the samples provided with the reflection film as 0 (Å) are respectively shown.

As can be understood from FIG.
In the case of a sample in which the Mn addition rate is 0 (atomic%) (corresponding to a reflective film composed only of Ag), the recording power varies depending on the film thickness of the reflective film. When the film thickness is 400 (Å), the recording power is about 8.0 (mW). 300
It was about 6.2 (mW) for (Å) and about 5.4 (mW) for 200 (Å).

On the other hand, the recording power is reduced by increasing the Mn addition rate. For example, the Mn addition rate is set to 2 (atomic%).
(Corresponding to the reflective film of Ag ₉₈ Mn ₂ )
Approximately 6.0 (mW) at 400 (Å) and approximately 5.0 at 300 (300)
(MW) and 200 (Å), the recording power could be reduced to about 4.4 (mW), respectively.

When the thickness of the reflective film is 400 (Å), the curve a
As can be understood from the above, as the Mn addition rate is increased from 2 (atomic%) described above, the recording power shows a decreasing tendency, and the sample manufactured with the Mn addition rate of 45 (atomic%) has a recording power of about 45%.
A recording power of 4.0 (mW) was obtained, and even if the addition rate was 45 (atomic%) or more, a substantial reduction in the recording power could not be achieved.

On the other hand, this film thickness is set to 300 (Å) (curve b) or 200 (curve b).
In the case of (Å) (curve c), it can be understood that the recording power, which once showed a decreasing tendency, increases again as the Mn addition rate increases.

Next, with reference to FIG. 2, the relationship between the measurement result of the CN ratio and the Mn addition ratio for the recording medium of Example 1 will be described.

FIG. 2 is a graph showing the relationship between the addition ratio and the CN ratio described above, in which the vertical axis represents the CN ratio (dB) and the horizontal axis represents the Mn in Ag-Mn.
FIG. 4 is a characteristic curve diagram showing the addition rate (atomic%) of each of them. In the same figure, like in FIG. 1, reference numerals are given to the curves corresponding to the respective film thicknesses.

As can be understood from FIG. 2, the reflection film
In the case of the sample (curve a) in which the Mn addition rate was 0 (atomic%) (corresponding to a reflection film composed of only Ag), the CN ratio was about 48.0 (dB) regardless of the film thickness. The decrease in the CN ratio due to the increase in the Mn addition rate is due to the fact that the addition rate is 7 (atomic%).
(Equivalent to the reflective film of Ag ₉₃ Mn ₇ ) was not substantially observed in the range up to about 48.0 (dB). Further, it can be understood that the CN ratio decreases as the Mn addition rate increases from 7 (atomic%) described above. The degree of the decrease becomes larger as the thickness of the reflection film becomes smaller, and the Mn addition rate becomes 45%.
(Atomic%) (Ag ₅₅ Mn ₄₅ )
Approximately 44.0 (dB) when the film thickness is 400 (Å) (curve a), 300
About 43.0 (dB) (curve b) in (Å), 39 in 200 (Å)
(DB) (CN).

Hereinafter, with reference to FIGS. 1 and 2 described above, a preferred range of the Mn addition rate in the reflective film composed of Ag-Mn of the first invention will be described.

As can be understood from the results shown in these two characteristic curves, the relationship between the Mn addition rate and the recording power differs depending on the thickness of the reflective film. As the rate is increased, the recording power can be reduced. However, when the reflective film is formed with a thickness of 300 (Å) or less, the ratio of light dropping due to the deterioration of the reflection characteristics due to the increase of the Mn addition ratio becomes larger, and the CN ratio decreases and the recording rate decreases. Comes with increased power.

From these findings, the lower limit of the preferable range of the Mn addition rate may be set from the measurement result of the recording power, and the upper limit of the range may be set from the measurement result of the CN ratio.

First, as can be understood from the curve shown in FIG. 1, the recording power can be reduced as the Mn addition rate is increased within a relatively low value range. Here, paying attention to the slope of the curve, this slope indicates that the Mn addition rate is about 3.5 (atomic%).
It can be understood that it gradually starts to decrease from the vicinity. Therefore, the lower limit of the addition ratio of Mn in Ag-Mn includes the above-mentioned values, and is preferably set to 2 (atomic%) or more.

For CN ratio, see ISO (International Organiz
According to international standards of the International Standards Organization, the number of revolutions is 1800 (rpm) and the frequency is 3.7 (MH
When writing in z), it is required to satisfy 45 (dB) or more. Therefore, it can be understood that the addition rate of Mn that satisfies this standard is determined from FIG. 2 and the addition rate should be 32 (atomic%) or less.

As can be understood from the above description, Ag-Mn can be used to obtain a reflective film that can be written with a smaller recording power as compared with the case where the reflective film is composed of silver alone and has a practical read sensitivity. It is preferable that the addition ratio of Mn is set to 2 (at.%) Or more and 32 (at.%) Or less.

Example 2 In Example 2, a reflective film formed of silver (Ag), manganese (Mn), and tin (Sn) was formed by changing the addition ratio of Mn and Sn to various values. The results of measuring the recording power and the CN ratio will be described. The measurement of characteristics and the production of a recording medium serving as a sample for the measurement were performed under the same conditions as described in Example 1. Therefore, in the following description, in order to avoid redundant description,
Only the measurement results will be described with reference to the drawings. Also,
In changing the addition rate of Mn and Sn, a plurality of recording media were prepared by changing only the addition rate of Sn under the condition that the addition rate of Mn in Ag-Mn-Sn was constant. Done. Further, in this embodiment, the thickness of the reflective film is set to 400
The recording medium prepared as (作 製) and the film thickness of 200
The measurement results with the recording medium manufactured as (Å) will be described.

FIGS. 3A and 3B show the relationship between the Mn addition ratio and Sn addition ratio in Ag-Mn-Sn and the recording power, and the recording power (mW) on the vertical axis and the horizontal axis on the horizontal axis. FIG. 5 is a characteristic curve diagram showing the addition ratio (atomic%) of Sn. Of these characteristic curves, FIG. 3 (A) shows that the thickness of the reflective film is 400.
FIG. 3B shows the measurement results when the film thickness was set to 200 (Å). Further, in these figures, the curve I represents Ag and Sn without addition of Mn in order to compare with the reflection film according to the second invention.
3 shows the measurement results of the samples prepared by changing the composition in various ways. In curves II to V, the addition ratio of Mn is constant at 1 (at.%), 7 (at.%), 15 (at.%) Or 30 (at.%), And is 0 to 35 (at.%), Respectively. Within the range of
3 shows the measurement results of a plurality of samples prepared by changing the addition ratios of various samples. To facilitate understanding of the description of these curves, Curve I is “Ag _100-X Sn _X ” and Curve II is “Ag _99-X Mn
`` Sn <sub>X</sub> '', Curve III `` Ag _93-X Mn ₇ Sn _X '', Curve IV `` Ag
The composition of the reflective film of the measurement sample represented by each curve, such as “Ag _70-X Mn ₃₀ Sn _X ” (where X> 0), is comprehensively included in “ _85-X Mn ₁₅ Sn _X ” and curve V. Expressions are given.

First, in the reflection film having a thickness of 400 (Å), from the comparison between the curves I and II shown in FIG.
Compared to the case of adding only Mn, 1 (atomic%) Mn
When Sn is added, the recording power is greatly reduced. Further, from the comparison between the curves I and III to V, it can be understood that the recording power takes a smaller value as the Mn addition ratio is larger at a predetermined Sn addition ratio.

Hereinafter, specific numerical values will be exemplified for the relationship between the reflective film composition and the recording power indicated by the curves IV in FIG. 3 (A).

First, comparing the recording power when the Sn addition rate is 1 (atomic%), that is, x = 1, the recording medium (Ag _100-x Sn _x : ie, Ag ₉₉ Sn ₁ ) according to the curve I is about 7.6. (MW) recording power, whereas the recording medium (Ag
_99-x Mn ₁ Sn _x : about 5.7 (mW) for Ag ₉₈ Mn ₁ Sn ₁ ), curve II
The recording medium according to curve I (Ag _93-x Mn ₇ Sn _x : Ag ₉₂ Mn ₇ Sn ₁ ) is about 5.0 (mW), and the recording medium according to curve IV (Ag _85-x Mn ₁₅ Sn _x :
That is, about 4.3 (mW) for Ag ₈₄ Mn ₁₅ Sn ₁ ) and about 4.0 for the recording medium according to curve V (Ag _70-x Mn ₃₀ Sn _x : Ag ₆₉ Mn ₃₀ Sn ₁ ).
(MW) of each recording power.

Further, this is the upper limit of the recording power measurement of the second embodiment.
If the addition ratio of Sn is 35 (atomic%), that is, x = 35, the recording medium (Ag _100-x Sn _x : that is, Ag ₆₅ S
n ₃₅ ) has a recording power of about 5.5 (mW),
Recording medium according to curve II (Ag _99-x Mn ₁ Sn _x : Ag ₆₄ Mn ₁ S
n ₃₅ ) is about 4.1 (mW), and the recording medium (Ag
_93-x Mn ₇ Sn _x : about ₅₈ (mW) for Ag ₅₈ Mn ₇ Sn ₃₅ ), curve I
Recording medium according to _{V (Ag 85-x Mn 15} Sn x: i.e. Ag ₅₀ Mn ₁₅ Sn ₃₅₎
Then, about 3.6 (mW) and the recording medium (Ag _70-x Mn
₃₀ Sn _x : Ag ₃₅ Mn ₃₀ Sn ₃₅ ) was about 3.3 (mW).
Even when the Mn addition ratio was set to a value larger than 30 (atomic%), the recording power could be reduced in accordance with each Sn addition ratio. However, this third
As can be understood from the comparison of the curves II to V shown in FIG. 7A, the recording obtained when the Sn addition rate is increased as the proportion of Mn in the Ag—Mn—Sn reflection film increases. It is recognized that the degree of power reduction tends to be small.

Next, even with the reflective film having a film thickness of 200 (Å), the comparison between the curves I and II shown in FIG. 3B shows that Ag is smaller than that of the recording medium having the Ag-Sn reflective film. And 1 (atomic%) Mn
On the other hand, in the recording medium to which Sn is added, the degree of reduction of the recording power is large. Further, from the comparison between the above-described curve I and the curves III to V, when the thickness of the reflective film is as thin as 200 (Å),
It can be understood that the recording power shows a complicated change depending on the Mn addition rate and the Sn addition rate.

Specific numerical values are shown as examples of the relationship between the composition of the reflective film and the recording power indicated by the curves IV in FIG. 3B.

First, when comparing the recording power when the Sn addition rate is 1 (atomic%), that is, x = 1, the recording medium (Ag _100-x Sn _x : ie, Ag ₉₉ Sn ₁ ) according to the curve I is about 5.5. (MW) recording power, whereas the recording medium (Ag
_{For 99-x} Mn ₁ Sn _x : Ag ₉₈ Mn ₁ Sn ₁ ), about 4.4 (mW), curve II
For the recording medium according to I (Ag _93-x Mn ₇ Sn _x : ie Ag ₉₂ Mn ₇ Sn ₁ ), about 3.4 (mW), the recording medium according to curve IV (Ag _85-x Mn ₁₅ Sn _x :
That is, about 2.9 (mW) for Ag ₈₄ Mn ₁₅ Sn ₁ ) and about 3.5 for the recording medium (Ag _70-x Mn ₃₀ Sn _x : Ag ₆₉ Mn ₃₀ Sn ₁ ) related to the curve V.
(MW) of each recording power.

As can be seen from FIG. 3 (B), by increasing the Sn addition rate, Ag-Sn is obtained regardless of the Mn addition rate in a range where the addition rate is relatively small.
Although the recording power can be reduced as compared with the reflective film, the recording power tends to increase as the Sn addition rate increases. This is probably because the reflective film is formed with a small film thickness of about 200 (Å), so that the transmittance increases as the Sn addition rate increases, and the recording power used for writing cannot be used effectively. .

Also, it can be understood that, in the reflective film made of Ag-Mn-Sn, the higher the Mn addition ratio is, the smaller the Sn addition ratio when the recording power starts to increase.

Next, with reference to FIGS. 4A and 4B, the relationship between the measurement result of the CN ratio of the recording medium of the above-described embodiment 2 and the addition rates of Mn and Sn will be described.

FIGS. 4 (A) and (B) illustrate the relationship between the Mn and Sn addition rates and the CN ratio for the recording medium according to Example 2, and the vertical axis shows the CN ratio (dB) and the horizontal axis shows the CN ratio. FIG. 4 (A) is a characteristic curve diagram showing Sn addition rates (atomic%), respectively.
4 shows the result when the thickness of the reflection film is 400 (Å), and FIG. 4 (B) shows the result when the thickness is 200 (Å). Further, the curves shown in these figures are accompanied by the signs of the curves I to V corresponding to FIGS. 3 (A) and (B).
A comprehensive composition formula of the reflection film of the recording medium represented by each curve is given.

First, in the case of a recording medium provided with a reflective film having a relatively large film thickness of 400 (Å), as can be understood from the curves IV shown in FIG. In the recording medium prepared by adding C, the CN ratio generally decreased. If the addition ratio of Sn, which decreases to the CN ratio of 45 (dB), which is the above-mentioned ISO international standard, is shown, the recording medium (curve I) manufactured without adding Mn has a Mn content of about 32 (atomic%). Is about 28 (atomic%) in the recording medium (curve II) to which 1 (atomic%) is added, and is recording medium (curve III) in which Mn is added to 7 (atomic%).
Is about 24 (at.%), And about 18 (at.%) And Mn is 30 (at.%) For the recording medium (curve IV) to which Mn is added at 15 (at.%).
About 6.5 (atomic%) in the recording medium (curve V) to which is added
Of the respective values.

Next, as can be understood from the curve shown in FIG. 4 (B), even in the case of a recording medium having a reflective film having a relatively small film thickness of 200 (Å), the decrease in the CN ratio is generally reduced. I came. Focusing on the addition ratio of Sn, which is reduced to the above-mentioned 45 (dB) CN ratio, in the recording medium (curve I) manufactured without adding Mn, approximately 27 (atomic%) and Mn is 1 (atomic%) ) The added recording medium (Curve II) was about 23 (atomic%), the Mn added 7 (atomic%) was about 20 (atomic%), and Mn was added at 15 (atomic%). The value was about 14 (atomic%) for the medium (curve IV) and about 3 (atomic%) for the recording medium (curve V) to which Mn was added at 30 (atomic%).

As can be understood from a comparison between FIGS. 3 (A) and 4 (A) and FIGS. 3 (B) and 4 (B), the thickness of the reflective film having the same composition is reduced. By adopting it, the CN ratio decreases. Therefore, a practically usable CN
In order to achieve the ratio and reduce the recording power, Ag
In constructing the reflective film made of -Mn-Sn, it is necessary to set narrower suitable ranges for the Mn addition rate and the Sn addition rate based on the result when the film thickness is small.

Hereinafter, with reference to FIG. 3 (B) and FIG. 4 (B), the Mn addition rate of the reflective film composed of Ag-Mn-Sn of the second invention will be described.
The preferred range of the Sn addition rate will be described.

First, a preferable range of the manganese (Mn) addition rate will be described.

First, as can be understood from a comparison between the curves I and II to V shown in FIG. 3 (B), when the Mn addition rate is 1 (atomic%) or more, the ratio is higher than when only Sn is added to Ag. As a result, a sufficient effect of reducing the recording power can be obtained.

On the other hand, paying attention to the range of the Sn addition rate which can achieve the CN ratio of 45 (dB) or more shown in FIG.
(Atomic%)), the decrease in the CN ratio is relatively gradual when the Sn addition rate is in the range of about 3 to 7 (atomic%). This tendency is indicated by curve II (Mn addition rate 1 (atomic%)), curve
III (Mn addition rate 7 (atomic%)) and curve IV (Mn addition rate 15
(Atomic%)). In contrast, Mn
In the curve V where the addition rate is 30 (atomic%), the tendency of the decrease in the CN ratio is continuously observed at any Sn addition rate within the measured range. As can be understood from the above, the preferable range of the Mn addition rate may be set to 15 (atomic%) or less.

As described above, it can be understood that the preferable range of the Mn addition rate should be set to 1 (at.%) Or more and 15 (at.%) Or less from the effect of reducing the recording power and the decrease in the CN ratio.

 Next, a preferable range of the tin (Sn) addition rate will be described.

First, from FIG. 3 (B), while the recording medium having a reflective film composed of Ag alone has a recording power of about 5.7 (mW), the Sn addition rate is set to 1 (atomic%) or more. Then, any of the Mn addition rates shown as curves II to V,
(%) Or more of the recording power can be reduced.

Further, as already described with reference to the measurement results of the CN ratio shown in FIG. 4 (B), the upper limit of the Sn addition rate is set to a value of 45 dB or more according to the international standard which is considered to be sufficient for practical use. What is necessary is just to set so that a ratio may be satisfied.

Therefore, the composition range obtained from the measurement results of Example 2 according to the second invention and using Ag-Mn-Sn as the reflection film is as follows from the result shown by the curve II, the composition of Ag _99-x Mn ₁ Sn _x In the case of the reflective film composition represented by the formula, the tin (Sn) addition rate is 1
(Atomic%) or more and 23 (atomic%) or less From the results shown in the curve III, in the case of the reflective film composition represented by the composition formula of Ag _93-x Mn ₇ Sn _x , the addition rate of tin (Sn) was 1
(Atomic%) or more 20 (atomic%) The results shown below the curve IV, when the reflective film composition represented by a composition formula of Ag _85-x Mn ₁₅ Sn _x is the addition ratio of tin (Sn) 1
(Atomic%) or more and 14 (atomic%) or less, respectively, and the composition range of manganese (Mn) is preferably 1 (atomic%) or more and 15 (atomic%) or less.
(At.%) Or less, and further, regarding the composition range of silver (Ag), the maximum value is 98 (at.%) From the above, and the minimum value is 71 (at.%) From the above. , Ag-Mn-Sn, the composition range of each component of the reflection film is such that the addition ratio of manganese (Mn) is 1 (at.%) Or more.
(Atomic%) or less, tin (Sn) addition rate is 1 (atomic%) or more
It is preferable that the addition ratio of silver (Ag) is set to 71 (at%) or more and 98 (at%) or less.

Third Embodiment In the third embodiment, instead of the recording medium of the first and second embodiments, a recording medium having a lamination relationship shown in FIG. 5A is used as another configuration example of the magneto-optical recording medium. Made,
The recording power and CN ratio were measured.

Describing the film thickness and material of each component, the protective film 13a made of silicon aluminum nitride (AlSiN) with a film thickness of 700 (Å) and the film thickness of 300 (Å) are formed on the surface of the substrate 11 made of polycarbonate. The magnetic film 15 composed of Tb-Fe-Co having a composition and the protective film 1 composed of AlSiN described above with a thickness of 1000 (上述)
3b is sequentially formed.

Thereafter, the surface of the protective film 13b is coated with the Ag according to the second invention.
An example of reflective film structure -mn-Sn-based, Ag ₈₆ Mn ₇ a reflective film represented by the composition formula of Sn ₇ is deposited in a film thickness of 400 (Å) or 200 (Å), Example 3 Such a magneto-optical recording medium 19 was obtained.

The deposition of the components including the protective film was performed under the same conditions as those in the above-described Examples 1 and 2.

In addition, a recording medium was separately manufactured under the same conditions except that a reflective film made of only Ag was provided, and the recording power and CN ratio of these two recording media were measured by the above-described procedure and numerical conditions. did.

As a result, in the recording medium according to the comparative example manufactured by setting the thickness of the reflective film to 400 (Å), the recording power of 8 (mW) and
A CN ratio of 50.4 (dB) was obtained. On the other hand, when the above film thickness is 200
With the recording medium according to the comparative example described as (Å), a recording power of 5.7 (mW) and a CN ratio of 50.2 (dB) were obtained.

On the other hand, in the recording medium according to the third embodiment in which the thickness of the reflective film is 400 (Å), the recording power of 4.5 (mW) and
A CN ratio of 50.1 (dB), which is substantially the same as that of the comparative example, was obtained. Example 3 in which the film thickness was set to 200 (Å)
In the recording medium according to the above, the recording power of 3.1 (mW) and 50.0
(DB) CN ratio was obtained.

As can be understood from the results, the recording sensitivity of the recording medium of Example 2 according to the present application and the conventional recording medium according to the comparative example can be changed by changing the arrangement position of the protective film. The CN ratio can be improved by the Kerr effect enhancement without lowering the CNR. Therefore, in producing a magneto-optical recording medium with various lamination relationships, by using the invention according to this application, a CN ratio higher than the result measured as the recording medium according to Example 1 and Example 2 can be obtained. Can be realized.

Although the embodiments of the invention according to the present application have been described above in detail, it is obvious that the invention is not limited to the above-described embodiments.

For example, in the above-described embodiment, the material, the film thickness, and other specific conditions have been described for the substrate, the magnetic film, and the protective film constituting the magneto-optical recording medium. However, the effect of the present invention cannot be obtained only under these conditions.

Further, a recording medium having a predetermined reflection film composition was manufactured as an example according to the first invention and the second invention, and the preferred range was described. However, the invention according to this application can obtain an effect only within this preferred range. It is clear that this is not something that can be done.
For example, in Example 2, in order to facilitate understanding of the description, a predetermined Mn addition rate was exemplified, and a suitable range of the Sn addition rate was examined under the condition where the Mn addition rate was constant. However, the composition range of the Mn addition rate and the Sn addition rate is not effective only within the preferred range exemplified as the examples, and the recording medium manufactured by arbitrarily suitably changing the exemplified reflection film composition. Even so, the same effect can be expected.

In addition to this, in the above-described series of embodiments, when configuring the reflection film, a description has been given by exemplifying a predetermined film thickness.
The invention according to this application is not limited only to the illustrated film thickness. Although detailed data is omitted, according to the experiment of the inventor of the present application, the thickness of the reflective film is set to 500 (Å).
In this case, heat that can be used for writing in the magnetic film is dissipated through the reflective film, making it difficult to achieve good recording power. Furthermore, the thickness of the reflective film is set to 100
In the case of (Å), the reflective film itself becomes transparent, and an effective car enhancement effect cannot be obtained.
The decrease in the ratio and the increase in the recording power were remarkable. Therefore,
In applying the present invention, the thickness of the reflective film is set to 200 to 4
If it is set to about 00 (Å), a magneto-optical recording medium having good recording sensitivity can be realized.

It is clear that these materials, film thicknesses, arrangement relations, numerical conditions, and other specific conditions can be changed and modified in any suitable design within the scope of the present invention.

(Effects of the Invention) As is clear from the above description, first, according to the magneto-optical recording medium of the first invention of this application, a reflection film is formed by silver (Ag) and manganese (Mn). Thereby, the reflectivity of Ag can be used, and the thermal conductivity of the reflective film can be reduced by Mn.

Further, according to the magneto-optical recording medium of the second invention of the present application, the reflection film is composed of three elements of silver (Ag), manganese (Mn) and tin (Sn), thereby achieving the same effect as the first invention. In addition, while utilizing the reflectivity of Ag, the thermal conductivity of the reflective film can be reduced by Mn and Sn.

Therefore, by implementing the first invention and the second invention according to this application, it is possible to maintain a practically sufficient CN ratio and achieve a low thermal conductivity, thereby reducing the recording power and achieving an excellent magneto-optical A recording medium can be provided.

[Brief description of the drawings]

FIG. 1 is a characteristic curve diagram showing the recording power on the vertical axis and the addition ratio of Mn in Ag-Mn on the horizontal axis, respectively, for explaining Example 1 according to the first invention. In order to explain Example 1 according to the first invention, a vertical axis shows a CN ratio, and a horizontal axis shows a Mn addition ratio in Ag-Mn, and FIG. 3 (A) and FIG. B) describes the second embodiment according to the second invention, in which the vertical axis represents the recording power and the horizontal axis represents Ag-Mn.
FIG. 4 (A) and (B) are characteristic curve diagrams each showing the addition ratio of Sn in -Sn, in which the vertical axis represents the CN ratio, and the horizontal axis represents the second embodiment according to the second invention. FIG. 5 is a characteristic curve diagram showing the addition ratio of Sn in Ag-Mn-Sn. FIGS. 5 (A) and (B) show the configuration of a magneto-optical recording medium in order to explain a conventional technique and an embodiment. It is explanatory drawing shown by a schematic cross section. 11 ... substrate, 13a, 13b ... protective film 15 ... magnetic film, 17 ... reflective film 19, 21 ... magneto-optical recording medium.

Claims (5)

(57) [Claims] 1. A magneto-optical recording medium comprising at least a magnetic film and a reflective film on a substrate, wherein the reflective film comprises silver (Ag) and manganese (Mn);
A magneto-optical recording medium, wherein the addition ratio of manganese (Mn) is 2 (at.%) Or more and 32 (at.%) Or less. 2. A magneto-optical recording medium comprising at least a magnetic film and a reflective film on a substrate, wherein the reflective film comprises silver (Ag), manganese (Mn), tin (Sn), and silver (Ag). Ag) is added at 71 (at.%) To 98 (at.%), Manganese (Mn) is added at 1 (at.%) To 15 (at.%), And tin (Sn) is added at 1 (at.). atom%)
A magneto-optical recording medium characterized by being at least 23 (atomic%) or less. 3. A silver (Ag) -manganese (Mn) of the reflection film.
-The addition rate of manganese (Mn) in tin (Sn) is set to 1 (at.%), And the addition rate of tin (Sn) is set to 1 (at.%) Or more.
3. The magneto-optical recording medium according to claim 2, wherein the content is (atomic%) or less. 4. A silver (Ag) -manganese (Mn) for the reflection film.
-The addition rate of manganese (Mn) in tin (Sn) is 7 (at.%), And the addition rate of tin (Sn) is 1 (at.%) Or more.
3. The magneto-optical recording medium according to claim 2, wherein the content is (atomic%) or less. 5. The reflective film according to claim 1, wherein said reflective film is silver (Ag) -manganese (Mn).
The tin (Sn) addition rate of manganese (Mn) is 15 (atomic%), and the tin (Sn) addition rate is 1 (atomic%) or more;
3. The magneto-optical recording medium according to claim 2, wherein the content is (atomic%) or less.