KR100667116B1 - Optical recording medium, magnetooptic recording medium, information recording/reproducing method and magnetic recording device - Google Patents

Abstract

An optical recording medium and a magneto-optical recording medium of a laminated structure in which a reflective layer, a nucleation base layer, a nucleation layer, and a recording layer are formed in this order on a substrate having a parallel plane formed of polycarbonate or the like, and the reflective layer and the recording layer The surface of the nucleation layer formed in between is made into the minute uneven | corrugated shape which has the nucleus (protrusion part) of a microparticle diameter.

Optical recording medium, magneto-optical recording medium, reflective layer, recording layer, nucleation layer

Description

Optical recording medium, magneto-optical recording medium, information recording / reproducing method and magnetic recording device {OPTICAL RECORDING MEDIUM, MAGNETOOPTIC RECORDING MEDIUM, INFORMATION RECORDING / REPRODUCING METHOD AND MAGNETIC RECORDING DEVICE}

The present invention relates to an optical recording medium, a magneto-optical recording medium, an information recording / reproducing apparatus, an information recording / reproducing method, and a magnetic recording apparatus.

Most of conventional optical recording media and magneto-optical recording media are laminated with a protective layer, a recording layer, a reflective layer (heat radiating layer) and the like on a substrate having a thickness of about 1.0 mm, and these laminated films do not exist. The light beam is irradiated from the substrate side, and information recording / reproducing is performed. The irradiation method over such a substrate is called a conventional method for convenience. An example of a magneto-optical recording medium employing a conventional method is disclosed, for example, in Japanese Patent Laid-Open No. 2000-82245.

Further, as one of means for realizing a high density optical recording medium and a magneto-optical recording medium, the spot size of the light beam irradiated to the recording film is reduced. In general, when the spot size is φ, the numerical aperture of the objective lens is NA, and the wavelength of the light beam (laser light) is λ, a relational expression of φ = λ / 2 NA is established. In other words, to make the spot size? Small, it is effective to increase the numerical aperture NA of the objective lens by making the wavelength? Constant.

However, the larger the numerical aperture NA, the shorter the focal length and the larger the aberration when the unevenness of the substrate thickness or the inclination of the substrate occurs, so the substrate thickness needs to be as thin as possible.

Therefore, in order to realize a high-density optical recording medium and a magneto-optical recording medium, it is more preferable to perform recording / reproducing by irradiating beam light from a side on which a laminated film such as a recording layer is formed. Hereinafter, the method of irradiating beam light from the side in which laminated films, such as a recording layer, are formed is called front illumination system for convenience.

1 is a schematic diagram showing a laminated structure of a conventional front illumination system magneto-optical recording medium. In addition, although the laminated structure in FIG. 1 shows a cross section, the parallel diagonal line which shows a cross section is abbreviate | omitted in consideration of the ease of understanding and the easiness of seeing (it is the same also about the laminated structure in the following angle). The magneto-optical recording medium is a laminated structure in which the reflective layer 2, the recording layer 8, the protective layer 13, and the coat layer 14 are formed in this order on the substrate 1. This laminated structure corresponds to the front illumination method, wherein the beam light (laser light) LB for recording / reproducing from the outside of the coat layer 14 is interposed between the coat layer 14 and the recording layer 8 via the objective lens L. Investigate towards

The substrate 1 is made of polycarbonate or the like and has a parallel plane. The reflective layer 2 is usually formed of a metal film or an alloy film such as aluminum, and reflects the incident beam light LB to the incident side. Since the reflective layer 2 also needs to perform a heat dissipation effect, the reflective layer 2 usually has a film thickness of about 50 nm or more.

In recording / reproducing by such a magneto-optical recording medium, it is necessary to form small recording marks in order to perform high density recording / reproducing. As a result, the recording layer 8 needs to have a fine grain structure and a surface structure. However, since the recording layer 8 is in contact with the reflective layer 2 and the protective layer 13 which have many irregularities on the surface and is affected by the irregularities, the recording layer 8 has a very deteriorated particle structure and surface structure. As a result, there is a problem that the recorded mark is in an uneven shape and the signal quality is lowered.

This problem is common to not only the magneto-optical recording medium but also a phase change (phase transition) optical recording film medium.

In addition, in the magneto-optical recording medium, when the saturation magnetization Ms of the recording layer 8 is large, the function of the semi-magnetic field of the recording layer 8 itself increases, so that an external magnetic field is not applied or a magnetic field in the erasing direction is applied. There is a problem that recording is performed even in the state. Recording is also performed in the magnetic field in the erasing direction, which is not preferable because a large recording magnetic field is required when performing magnetic field modulation recording.

In addition, there is a problem that the mark (recording mark) shifts during recording due to the influence of the semi-magnetic field of the recording layer 8. In particular, an increase in the effective recording magnetic field in the mark immediately after the long mark (long mark) (produced by applying the magnetic field of the magnetic head to the semi-magnetic field of the recording layer 8) is likely to cause shift of the mark. This is accompanied by a cause of deterioration of jitter in a random pattern. In addition, by forming the recording auxiliary layer, it is possible to reduce the half magnetic field by the recording layer to reduce the recording magnetic field, but there is a problem that the coercive force of the recording layer is reduced by the action of the recording auxiliary layer. The decrease in coercive force is not preferable because the micro mark cannot be stably maintained. In addition, Japanese Patent Application Laid-open No. Hei 11-126384 is a document which discloses a technique for a recording auxiliary layer.

This invention is made in view of such a situation, and an object of this invention is to form a nucleation layer as a base of a recording layer, and to refine | miniaturize a recording layer (fine particle structure, fine surface structure). In addition, by forming a recording layer having a fine grain structure and a surface structure, it is possible to form small recording marks, and an object thereof is to provide an optical recording medium capable of high-density recording / reproducing.

Further, an object of the present invention is to provide a magneto-optical recording medium capable of increasing the coercive force of a recording layer even when a recording auxiliary layer is provided, and capable of high density recording / reproducing.

It is also an object of the present invention to provide an information recording / reproducing apparatus, an information recording / reproducing method, and a magnetic recording apparatus using the above-described optical recording medium or magneto-optical recording medium.

<Start of invention>

The optical recording medium of the first invention is an optical recording medium in which a reflection layer and a recording layer are formed in this order on a substrate and irradiates light from the recording layer side to record / reproduce information. It is provided between the reflective layer and the recording layer.

The optical recording medium of the second invention is, in the first invention, the nucleation layer is formed of W, Mo, Ta, Fe, Co, Ni, Cr, Pt, Ti, P, Au, Cu, Al, Ag, Si, Gd, It is formed of a material containing one or more elements selected from the group consisting of Tb, Nd, and Pd.

In the optical recording medium of the third invention, in the first invention or the second invention, the surface roughness of the nucleation layer is 0.3 nm to 1.5 nm.

In the optical recording medium of the fourth invention, in the first invention or the second invention, a plurality of nucleation layers are formed, and the surface tension of the nucleation layer formed on the recording layer side is stronger than the surface tension of the nucleation layer formed on the reflection layer side. do.

In the optical recording medium of the fifth invention, in the first invention or the second invention, the recording layer is capable of a phase change between the crystalline state and the amorphous state, and the reflectance in the crystalline state is different from that in the amorphous state. do.

In the optical recording medium of the first to fifth inventions, since the nucleation layer is formed as a base of the recording layer, the recording layer can be miniaturized (fine particle structure, fine surface structure). Further, by forming a recording layer having a fine grain structure and a surface structure, an optical recording medium capable of forming small recording marks, that is, high density recording / reproducing, can be provided.

The magneto-optical recording medium of the sixth invention is a magneto-optical recording medium in which a reflective layer and a recording layer having perpendicular magnetic anisotropy are formed in this order on a substrate, and the information is recorded / reproduced by irradiating light from the recording layer side. A nucleation layer having irregularities in the gap between the reflective layer and the recording layer.

The magneto-optical recording medium of the seventh invention is, in the sixth invention, the nucleation layer is formed of W, Mo, Ta, Fe, Co, Ni, Cr, Pt, Ti, P, Au, Cu, Al, Ag, Si, Gd. , Tb, Nd, and Pd, and formed of a material containing one or two or more elements selected from the group.

In the magneto-optical recording medium of the eighth invention, in the sixth invention or the seventh invention, the surface roughness of the nucleation layer is 0.3 nm to 1.5 nm.

In the sixth invention or the seventh invention, the magneto-optical recording medium of the ninth invention has a plurality of nucleation layers formed, and the surface tension of the nucleation layer formed on the recording layer side is stronger than the surface tension of the nucleation layer formed on the reflection layer side. Shall be.

In the optical recording medium of the sixth invention to the ninth invention, since the nucleation layer is formed as the base of the recording layer, the recording layer can be miniaturized (fine particle structure, fine surface structure). Further, by forming a recording layer having a fine grain structure and a surface structure, it is possible to provide a magneto-optical recording medium capable of forming small recording marks, that is, high density recording / reproducing.

In the sixth invention or the seventh invention, the magneto-optical recording medium of the tenth invention includes a recording auxiliary layer having perpendicular magnetic anisotropy between the reflective layer and the nucleation layer in order to eliminate the semi-magnetic field generated by the magnetization of the recording layer. Equipped.

The magneto-optical recording medium of the eleventh invention is, in the tenth invention, when the recording layer is a magnetic film of transition metal magnetization dominance, the recording auxiliary layer is a magnetic film of rare earth magnetization dominance.

The magneto-optical recording medium of the twelfth invention, in the tenth invention, when the recording layer is a magnetic film of rare earth magnetization dominance, the recording auxiliary layer is a magnetic film of transition metal magnetization dominance.

In the magneto-optical recording medium of the thirteenth invention, in the tenth invention, when the recording layer and the recording auxiliary layer are magnetic films of transition metal magnetization dominance, the Curie temperature of the recording auxiliary layer is set to be higher than the Curie temperature of the recording layer.

In the magneto-optical recording medium of the fourteenth invention, in the tenth invention, when the recording layer and the recording auxiliary layer are magnetic films of rare earth magnetization dominance, the Curie temperature of the recording auxiliary layer is set to be higher than the Curie temperature of the recording layer.

The magneto-optical recording medium of the tenth to fourteenth inventions aims to provide a magneto-optical recording medium capable of increasing the coercive force of the recording layer even when the recording auxiliary layer is formed, and capable of high density recording / reproducing. .

The information recording / reproducing apparatus of the fifteenth invention is to record / reproduce information by using the optical recording medium of the first invention or the second invention or the magneto-optical recording medium of the sixth invention or the seventh invention. .

In the information recording / reproducing apparatus of the fifteenth aspect of the present invention, since information is recorded / reproduced using either a high density optical recording medium or a magneto-optical recording medium, recording / reproducing of a high density information recording medium becomes possible. .

In the information recording and reproducing methods and apparatuses of the sixteenth invention and the seventeenth invention, the unevenness is formed on the surface between the heat diffusion layer and the recording layer of the magnetic recording medium in which a heat diffusion layer and a perpendicular magnetic anisotropy recording layer are formed in this order on the substrate. It is to be provided with a nucleation layer having a magnetic field, and a magneto-optical recording of information is performed by applying light and a magnetic field to a magnetic recording medium, and magnetic reproducing is performed by detecting magnetic flux from the recording layer side.

In the information recording and reproducing methods of the sixteenth invention and the seventeenth invention, the recording and reproducing of information is performed using a high-density magnetic recording medium, so that the high-density information recording medium can be recorded and reproduced.

In the eighteenth invention, an element for applying and heating light, an element for applying a magnetic field, and an element for detecting a magnetic flux are mounted on one slider.

1 is a schematic diagram showing a laminated structure of a conventional front illumination type magneto-optical recording medium.

2 is a schematic diagram showing a schematic laminated structure of a magneto-optical recording medium according to the present invention.

3 (a) and 3 (b) are schematic diagrams showing the surface shape state of the reflective layer.

4 is a schematic diagram showing a laminated structure of a magneto-optical recording medium (medium A) according to the first embodiment of the present invention.

5 is a schematic diagram showing a laminated structure of a conventional magneto-optical recording medium (medium C).

FIG. 6 is a graph showing the Hw-CNR characteristics of media A, B, and C. FIG.

7 is a chart comparing the characteristics of media A, B, and C. FIG.

8 is a graph showing mark length-jitter characteristics of media A, C. FIG.

9 (a) and 9 (b) are schematic diagrams illustrating the relationship between surface tension and surface shape in a laminated structure.

10 is a table showing surface tension of elements and the like.

Fig. 11 is a chart showing characteristics such as surface tension, surface roughness, surface grain size period, recording layer coercive force, etc. due to the nucleation layer material.

12 is a chart showing characteristics in the case of stacking a nucleation layer.

FIG. 13 is a schematic diagram showing a laminated structure of a magneto-optical recording medium (medium E) excluding the recording auxiliary layer from medium D. FIG.

14 is a graph showing the Hw-CNR characteristics of media D and E. FIG.

15A and 15B are schematic diagrams for explaining the action of the recording auxiliary layer in the magneto-optical recording medium (medium F) according to the second embodiment of the present invention.

Fig. 16 is a schematic diagram for explaining the action of the recording auxiliary layer in the magneto-optical recording medium (medium G) according to the second embodiment of the present invention.

FIG. 17 is a graph showing mark length-jitter characteristics of media D, F, and G. FIG.

Fig. 18 is a schematic diagram showing the laminated structure of the RAD system magneto-optical recording medium (the medium H) according to the third embodiment of the present invention.

Fig. 19 is a schematic diagram showing a laminated structure of a conventional RAD system magneto-optical recording medium (medium I).

20 is a chart comparing the characteristics of media H, I, J. FIG.

Fig. 21 is a schematic diagram showing a laminated structure of a DWDD-type magneto-optical recording medium (medium K) according to the fourth embodiment of the present invention.

Fig. 22 is a schematic diagram showing a laminated structure of a conventional DWDD-type magneto-optical recording medium (medium L).

23 is a chart comparing the characteristics of the media K, L, M;

Fig. 24 is a schematic diagram showing the laminated structure of the phase change type optical recording medium (medium N) according to the fifth embodiment of the present invention.

25 is a chart comparing the characteristics of mediums N and P;

Fig. 26 is a block diagram showing an outline of an information recording / reproducing apparatus according to a sixth embodiment of the present invention.

27 is a diagram showing an outline of a magnetic recording apparatus according to the seventh embodiment of the present invention.

Fig. 28 is a diagram for explaining the change in the coercivity and the saturation magnetization temperature of the magnetic recording medium of the present invention.

Fig. 29 is a graph showing the CNR characteristics with respect to laser recording power of the magnetic recording medium of the present invention.

30 is a view showing an integrated head used in the magnetic recording device of the present invention.

Fig. 31 is a graph showing the CNR characteristics with respect to the recording current of the magnetic recording medium of the present invention.

32 is a chart showing CNR characteristics of the base layer structure of the magnetic recording medium of the present invention.

<Best mode for carrying out the invention>

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.

(Schematic lamination structure of the recording medium according to the present invention)

2 is a schematic diagram showing a schematic laminated structure of a magneto-optical recording medium according to the present invention. Although the present invention describes the magneto-optical recording medium as an example, the same can be applied to the optical recording medium. In the case of an optical recording medium, the recording auxiliary layer becomes unnecessary.

In the magneto-optical recording medium according to the present invention, the reflective layer 2, the recording auxiliary layer 3, the nucleation base layer 4, and the nucleation layer 5 (more than two nucleation layers are laminated on the substrate 1). The first nucleation layer 5, the recording layer 8, the protective layer 13, and the coat layer 14 are laminated structures formed in this order. This laminated structure corresponds to the front illumination method as shown in FIG. 1, and the beam layer LB for recording / reproducing from the outside of the coat layer 14 is interposed between the coat layer 14 and the recording layer 8 via the objective lens L. FIG. Is irradiated towards. The substrate 1 is similar to the conventional magneto-optical recording medium, and is formed of polycarbonate or the like and has a parallel plane. The recording auxiliary layer 3 and the recording layer 8 are composed of a magnetic film having perpendicular magnetic anisotropy. For example, the recording auxiliary layer 3 is made rare earth magnetization dominant, and the recording layer 8 is transition metal magnetization. Dominate. The surface of the nucleation layer 5 has a fine concavo-convex shape having a nucleus (projection portion 5a) having a grain size. The protective layer 13 is formed of a nitride film or the like to prevent oxidation and nitriding of the recording layer 8. The coat layer 14 prevents dust and scratches.

3 (a) and 3 (b) are schematic diagrams showing the state of formation of the reflective layer. The reflective layer 2 is set to a film thickness of about 50 nm or more in order to obtain a heat dissipation effect, and has a smooth surface so that the shape of the substrate 1 underneath can be reflected. As a smooth surface, it is preferable that surface roughness Ra is about 0.3 nm or less. Moreover, surface roughness Ra roughly shows the grade of the surface roughness, and is generally represented by the difference between the average value of the height of a mountain part, and the average value of the height of a valley part.

 As a film-forming method of the reflective layer 2, there is a sputtering method using a metal target. FIG. 3A shows a cross-sectional shape of the reflective layer 2 formed by the sputtering method using a solid target composed only of Ag. In addition, the parallel diagonal line which shows a cross section like the case of the laminated structure of FIG. 1 is abbreviate | omitted. Since roughness of about half (25 nm) occurs with respect to the film thickness of 50 nm, it is not a smooth surface.

FIG. 3B shows a cross-sectional shape of the reflective layer 2 formed by the sputtering method using an alloy target formed by adding a predetermined amount of Pd, Cu, Si or the like to a metal containing Ag as a main component, for example. do. By addition of Pd, Cu, Si, etc., surface roughness Ra can be made into about 0.3 nm or less with respect to film thickness of 50 nm. It is because additive material, such as Pd, suppresses the particle size expansion of Ag.

As a method of smoothing the surface of the reflective layer 2, in addition to the method of adding a material such as Pd, there is also a method of forming a smooth surface by forming Ag thicker and then etching the surface. Moreover, it is also an effective method to make a dense and smooth surface by slowing film-forming rate by making the pressure in the process chamber at the time of film-forming into the low gas pressure of about 0.1 Pa or less. The smoothed reflective layer 2 is formed on the substrate 1.

The recording auxiliary layer 3 formed on the smooth reflective layer 2 has a magnetization functioning in a direction of eliminating the semi-magnetic field generated by the recording layer 8 when the recording magnetic field is applied. That is, the recording auxiliary layer 3 can reduce the recording magnetic field (magnetic field required for recording). In the case where the recording layer 8 is a single layer, in particular in the signal area immediately after a long mark (mark is a signal area having the same signal, and a long mark is a state in which the signal area having the same signal is continued), a signal at the time of recording Although the movement (shift) of the region occurs, the jitter can be improved by eliminating the shift by forming the recording auxiliary layer 3 which eliminates the semi-magnetic field (see FIGS. 15 and 16).

As the recording auxiliary layer 3, for example, a rare earth magnetization dominant magnetic film is formed. In order to make the direction and size of magnetization of the recording layer 8 to be formed later uniform, it is preferable that the recording auxiliary layer 3 serving as a base is formed with a low gas pressure to smooth the surface. When the recording layer 8 is formed on the basis of the recording auxiliary layer 3, the coercive force Hc of the recording layer 8 is compared with the case where the recording layer 8 is directly deposited on the reflective layer 2. Falls. This is because the perpendicular magnetic anisotropy of the recording layer 8 is lowered by the influence of the recording auxiliary layer 3 having the magnetization functioning in the direction opposite to the magnetization of the recording layer 8. There is a relationship of d = σ / (2MsHc) between the size d (normally corresponding to the length of the shortest mark) of the smallest magnetic domain (domain) that the recording layer 8 can hold, and the coercive force Hc and the saturation magnetization Ms. . Moreover, (sigma) is a constant determined by material, film-forming conditions, etc.

In other words, the decrease in the coercive force Hc increases the size d of the minimum magnetic domain, leading to a decrease in the recording density of the magneto-optical recording medium. Therefore, in order to achieve high density, it is necessary to decrease the size d of the minimum magnetic domain to increase the coercive force Hc.

In order to reduce the size d of the minimum magnetic domain, a nucleation layer 5 having an uneven shape on the surface is formed between the recording auxiliary layer 3 and the recording layer 8. It is preferable to make the surface of the nucleation layer 5 into the fine uneven | corrugated shape which has the nucleus 5a of a microparticle diameter in the period of about 60 nm or less. By the action of the surface shape of the nucleation layer 5, the recording layer 8 can be composed of minute domains (cylindrical domains) in which the magnetization directions are aligned. Since the direction of magnetization in the recording layer 8 is aligned, the coercive force Hc of the recording layer 8 increases, so that the size d of the minimum magnetic domain can be reduced. In other words, by forming the nucleation layer 5, it is possible to increase the density.

As the base of the nucleation layer 5, the nucleation base layer 4 is formed before the nucleation layer 5 is formed. In order to reliably control the uneven | corrugated shape of the surface of the nucleation layer 5 by forming the nucleation base layer 4 which has surface tension lower than the surface tension of the nucleation layer 5. The relationship between the surface tension of the nucleation base layer 4 and the surface tension of the nucleation layer 5 will be described later (see FIG. 9).

(First embodiment)

4 is a schematic diagram showing a laminated structure of a magneto-optical recording medium (hereinafter referred to as medium A) according to the first embodiment of the present invention. The medium A is formed on the substrate 1 on the reflective layer 2, the recording auxiliary layer 3, the nucleation base layer 4, the first nucleation layer 5, and the second nucleation layer 6 (nuclear encapsulation layer ( 6)), the recording layer 8, the protective layer 13, and the coating layer 14 are a laminated structure formed in this order. On the surface of the first nucleation layer 5 and the surface of the second nucleation layer 6, nuclei 5a and 6a having a small particle diameter are formed, respectively, to form a minute uneven surface. Corresponding to the front illumination method is the same as in FIG. 2 and the like, and detailed description is omitted. In addition, the present invention can also be applied to a conventional magneto-optical recording medium in which the structure is formed in a reverse order to form a laminated structure and is recorded over a substrate.

The detail of each layer structure of the medium A is as follows. In addition, a numerical value etc. are not limited to this and can change suitably as needed.

Substrate 1: A photopolymer land groove is formed on a glass plate having a diameter of 120 mm and a thickness of 1.2 mm. The widths of the lands and the grooves are each 0.25 탆. The depth of the groove is 30 nm. The deep ultraviolet (DUV) irradiation treatment forms a very smooth surface with a surface roughness of Ra0.25 nm or less.

Reflective layer (2): Ag, Pd, Cu, Si alloy film containing Ag as a main component. Thickness 50nm

Recording auxiliary layer 3: GdFeCo magnetic film. Thickness 5 nm. Since the recording layer 8 has a transition metal magnetization dominance, the recording auxiliary layer 3 has a rare earth magnetization dominance and has a Curie temperature higher than the Curie temperature of the recording layer 8. When the Curie temperature of the recording layer 8 has the vertical magnetization and the saturation magnetization Ms is a large composition, the recording magnetic field reduction effect is large. Here, the composition ratio of Gd25: Fe49: Co26 was taken.

Nucleation base layer 4: SiN film, thickness 0.5nm

First nucleus forming layer 5: Cr film, thickness 0.5nm

Second nucleus forming layer 6: C film, 0.5 nm thick

Recording layer 8: TbFeCo (Tb19: Fe62: Co19) magnetic film, thickness 25nm

Protective layer 13: SiN film, 50 nm in thickness

Coat layer 14: Transparent ultraviolet curable resin, 15 micrometers in thickness, The detail of each layer film-forming conditions of the medium A is as follows. This condition is also varied by the apparatus and the like, and is not limited to this, and can be changed as necessary.

Reflective layer 2: Simultaneous sputter film deposition of the alloy target and Si target which Pd and Cu were added as a main component of Ag. Gas pressure is 0.95 Pa, input power is 500 W as alloy target and 320 W as Si target.

Recording auxiliary layer 3: Sputter film deposition of the alloy target of GdFeCo. Gas pressure is 0.5 Pa, input power is 500 W.

Nucleation base layer 4: Sputter film-forming the Si target of B doping in nitrogen gas. Gas pressure is 0.3Pa, input power is 800W.

1st nucleus formation layer 5: Sputter film deposition of a Cr target. Gas pressure is 0.5 Pa, input power is 500 W.

2nd nucleus formation layer 6: Sputter film deposition of a C target. Gas pressure is 0.5 Pa, input power is 500 W.

Recording layer 8: Sputter film deposition of the alloy target of TbFeCo. Gas pressure is 1.0 Pa, input power is 500 W.

Protective layer 13: Sputter film-forming the Si target of B doping in nitrogen gas. Gas pressure is 0.5 Pa, input power is 800 W.

Coat layer 14: After apply | coating 15 micrometers in thickness of transparent ultraviolet curable resin by the spin coating method, it irradiates for 30 second and irradiates an ultraviolet-ray.

In order to compare the characteristics with the medium A, two types of magneto-optical recording media having a conventional structure were created. One is a magneto-optical recording medium (hereinafter referred to as medium B) having the structure shown in FIG. 1, and the other is an magneto-optical recording medium (hereinafter referred to as medium C) having the structure shown in FIG. . 5 is a schematic diagram showing the laminated structure of the medium C. FIG. The medium B is a magneto-optical recording medium having a structure in which the recording auxiliary layer 3, the nucleation base layer 4, the first nucleation layer 5, and the second nucleation layer 6 in the medium A are omitted. The medium C is a magneto-optical recording medium having a structure in which the nucleation base layer 4, the first nucleation layer 5, and the second nucleation layer 6 in the medium A are omitted. The film forming method, the film forming conditions, the thickness, and the like of the medium B and the medium C were the same as those of the medium A.

6 is a graph showing the Hw-CNR characteristics of media A, B, and C. FIG. The horizontal axis Hw represents the recording magnetic field (unit: Oe), and the vertical axis carrier CNR (Carrier to Noise Ratio) represents the signal-to-noise ratio (unit: dB). The rotational speed was 5.0 kW, the mark length was 0.25 µm, the recording power (recording time irradiation power) was 9.0 Hz, and the reproduction power (reproduction time irradiation power) was 3.4 Hz.

When the medium B and the medium C are compared, the recording magnetic field Hw is reduced in the medium C due to the effect of the recording auxiliary layer 3. In addition, in the recording direction (Hw> 0), the CNR of both the medium B and the medium C is lower than that of the medium A, which weakens the external magnetic field. This is because the coercive force Hc of the recording layer 8 is lowered.

7 is a chart comparing the characteristics of media A, B, and C. FIG. Corresponding to the presence or absence of the recording auxiliary layer 3 and the presence or absence of the nucleation layer 5, the recording layer coercive force Hc (kOe), the threshold Hwth (Oe) of the recording magnetic field, and the CNR for the mark length of 0.20 m and 0.25 m I) is shown. The rotation speed is 5.0 kW, the recording power is 9.0 kW, and the reproduction power is 3.4 kW. Compared with the medium C, in the medium A, the coercive force of the recording layer is increased, and in particular, the CNR at a short mark length is improved. That is, it can be confirmed that the densification can be achieved by the action of the nucleation layer 5.

8 is a graph showing mark length-jitter characteristics of media A, C. FIG. Mark length (unit: mm) is shown on the horizontal axis, and random jitter (unit:%) is shown on the vertical axis. By the action of the nucleation layer, it can be confirmed that the shift during recording is reduced, and in particular, random jitter at a short mark length is improved.

The nucleation base layer 4 is formed at the base of the nucleation layer 5 in order to provide a base having a lower surface tension as compared with Cr used as the nucleation layer 5. Next, the relationship between surface tension and surface shape in the laminated structure will be described.

9 (a) and 9 (b) are schematic diagrams illustrating the relationship between surface tension and surface shape in a laminated structure. FIG. 9A shows a case where the surface tension γ 1 of the nucleation base layer 4 is lower than the surface tension γ 2 of the nucleation layer 5. In this case, the material of the nucleation layer 5 tends to aggregate and grow at the time of film formation, and the surface particle diameter period? Of the nucleus 5a is shortened as indicated by? A in the drawing. That is, it becomes the surface shape which made the minute unevenness | corrugation. FIG. 9B shows the case where the surface tension γ 1 of the nucleation base layer 4 is higher than the surface tension γ 2 of the nucleation layer 5. In this case, the material of the nucleation layer 5 hardly aggregates at the time of film formation, the surface particle diameter period λ becomes long as indicated by λb in the drawing, and the particle size of the nucleus 5b also increases. That is, it becomes a smooth surface shape with long unevenness | corrugation of a long period.

10 is a chart showing surface tension of elements and the like. Surface tension (gamma) in 30 degreeC of various materials, such as an element, is shown. In order to make the surface shape of the nucleation layer 5 into a minute uneven shape as shown in Fig. 9A, the nucleation base layer is referred to according to the material of the nucleation layer 5 with reference to the surface tension of the material. What is necessary is just to select the material of (4) suitably.

In the medium A, the thickness of the Cr film of the first nucleation layer 5 was 0.5 nm, and the thickness of the C film of the second nucleation layer 6 was 0.5 nm. When the thickness is 0.5 nm or more, the surface particle diameter period? Of the nucleus 5a is longer than 60 nm, and the surface roughness Ra is increased to 1.5 nm or more. When the surface particle diameter period λ increases, the particle diameter (magnetic domain) of the recording layer 8 formed thereon also increases, and the recording resolution decreases. In addition, when the surface roughness Ra becomes large, the coercive force Hc of the recording layer 8 becomes high, which causes a problem that the recording magnetic field is insufficient during recording. That is, the nucleation layer 5 preferably has a surface roughness Ra of 0.5 nm to 1.5 nm and a surface grain size period? Of about 10 nm to 60 nm.

In the medium A, the material of the first nucleation layer 5 is made of Cr. However, when the material of the nucleation base layer 4 is made of SiN, if the material has a surface tension greater than that of SiN, the nucleus 5a is the same as that of Cr. ) Can be formed. In addition, the surface roughness Ra and the recording layer coercive force Hc can be variously changed by the material of the first nucleation layer 5 (nucleation layer 5).

Fig. 11 is a chart showing characteristics of surface tension, surface roughness, surface grain size period, recording layer coercive force and the like caused by the nucleation layer material. For example, Sample 1 shows the case where the nucleation layer material is Cr and the thickness of the formed film is 1 nm, the surface tension γ is 2290 mN / m at 30 ° C., the surface roughness is Ra1.3 nm, and the surface grain diameter period λ. Is 54 nm, the recording layer coercive force Hc is 7 kOe at 100 ° C, and the CNR is 0.2 µm in mark length and 41.6 ms.

In the medium A, the recording layer coercive force Hc can be made higher than the medium C only by the first nucleation layer 5 (nucleation layer 5) without forming the second nucleation layer 6. However, by forming the second nucleation layer 6, the surface roughness Ra is further enhanced to increase the recording layer coercive force Hc while maintaining the surface particle diameter period? Formed by the first nucleation layer 5. can do.

12 is a chart showing the characteristic when the nucleation layer is laminated. For example, the sample 18 shows the case where the nucleation layer material is Cr and the thickness of the formed film is 0.5 nm, the surface roughness is Ra1.1 nm, the surface grain diameter λ is 50 nm, and the recording layer coercive force Hc is 100 ° C. At 5.5 kOe, CNR indicates a mark length of 0.2 μm and 41 μs. Although sample 19 uses C as a 2nd nucleation layer material, it is also possible to use materials other than C. Sample 20 shows W, sample 21 uses Co, and sample 22 uses Ta as the second nucleation layer material. As described above, in the case of stacking the nucleation layer, as described in FIG. 9, when a material whose surface tension of the nucleation layer material on the upper layer is higher than the surface tension of the nucleation layer material on the lower layer side is selected, the material aggregates to form a nucleus. It is easy to grow, the surface particle diameter period (lambda) can be made small, and it can be set as an appropriate value.

Moreover, it is also possible to form a 3rd nucleation layer and a 4th nucleation layer further on the 2nd nucleation layer 6, and the sample 23 shows the case where the 3rd nucleation layer and the sample 24 form the 4th nucleation layer. The sample 24 shows the case where the 1st nucleation layer material is Cr, and the thickness of the formed film is 0.5 nm, Co is 2nd nucleation layer material, the thickness of the formed film is 0.2 nm, 3rd nucleation layer material is Ta, and is formed The thickness of one film is 0.2 nm, the fourth nucleation layer material is W, the thickness of the formed film is 0.2 nm, the surface roughness is Ra1.5 nm, the surface grain size period λ is 58 nm, the recording layer coercive force Hc is 7.3 kOe at 100 ° C, CNR indicates that the mark length is 0.2 µm and 42.0 mm 3.

By forming a plurality of nucleation layers, the surface roughness Ra and the surface particle diameter period? Of the surface of the nucleation layer can be changed, and the recording layer coercive force Hc and CNR can be further improved.

In the medium A, the recording layer 8 is a TbFeCo magnetic film having a transition metal magnetization dominant composition, and the recording auxiliary layer 3 is a GdFeCo magnetic film having a rare earth magnetization dominant composition. However, in the case where the recording layer 8 has a rare earth magnetization dominant composition, the recording auxiliary layer 3 can be made the transition metal magnetization dominant composition to reduce the recording magnetic field. In either case, it is preferable that the recording auxiliary layer 3 has a composition having vertical magnetization near the Curie temperature Tcm of the recording layer 8.

For example, in the medium A, instead of the composition ratio of Tb in the recording layer 8, the recording layer 8 is made of a TbFeCo magnetic film having a rare earth magnetization dominant composition, and the composition ratio of Gd in the recording auxiliary layer 3 is substituted. Thus, the medium having the recording auxiliary layer 3 as a GdFeCo magnetic film having a transition metal magnetization dominant composition is referred to as medium D. In the medium D, other film formation methods, film formation conditions, thickness, and the like are the same as in the case of the medium A.

FIG. 13 is a schematic diagram showing a laminated structure of a magneto-optical recording medium (hereinafter, medium E) excluding the recording auxiliary layer from the medium D. FIG. In order to compare the characteristics with the medium D, the medium E has a structure in which the recording auxiliary layer is removed from the stacked structure of the medium D, and other conditions are the same as in the case of the medium D (medium A). Therefore, the medium E is the substrate 1, the reflective layer 2, the nucleation base layer 4, the first nucleation layer 5, the second nucleation layer 6, the recording layer 8, the protective layer 13 And a laminated structure of the coat layer 14.

14 is a graph showing the Hw-CNR characteristics of the media D and E. FIG. The horizontal axis Hw represents the recording magnetic field (unit: Oe), and the vertical axis carrier CNR (Carrier to Noise Ratio) represents the signal-to-noise ratio (unit: dB). The rotational speed is 5.0 kV, the mark length is 0.25 µm, the recording power (recording time irradiation power) is 9.0 Hz, and the reproduction power (reproduction time irradiation power) is 3.4 Hz. The combination of the recording layer 8 made of the rare earth magnetization dominant magnetic film and the recording auxiliary layer 3 made of the transition metal magnetization dominant magnetic film has the effect of reducing the recording magnetic field Hw.

(2nd Example)

15A and 15B are schematic diagrams for explaining the operation of the recording auxiliary layer in the magneto-optical recording medium (medium F) according to the second embodiment of the present invention.

FIG. 15A shows a case where the mark length Lm is long, and FIG. 15B shows a case where the mark length Lm is short. The relative advancing direction of the beam light LB is indicated by arrow LBS. The temperature distribution Tmed which generate | occur | produces in a medium by irradiation of a beam light is shown typically (illustration is abbreviate | omitted in FIG.15 (b) since it is the same temperature distribution as FIG.15 (a)). It shows that the Curie temperature Tcs of the recording auxiliary layer 3 is higher than the Curie temperature Tcm of the recording layer 8 superimposed on the temperature distribution Tmed. A nucleation base layer 4 and a nucleation layer 5 are formed between the recording auxiliary layer 3 and the recording layer 8.

In the medium A, the recording auxiliary layer 3 is a magnetic film having the same transition metal magnetization dominance as the recording layer 8, and the Curie temperature Tcs of the recording auxiliary layer 3 is less than the Curie temperature Tcm of the recording layer 8. By making it high, the shift of the magnetic domain (mark) at the time of recording can be reduced. A medium that satisfies this condition is referred to as medium F. The structure of the medium F is basically the same as that of the medium A and the medium D, and the curable temperature Tcs is made higher than the Curie temperature Tcm by using the recording auxiliary layer 3 as the magnetic film of the transition metal magnetization dominance. Different from medium D. For example, Curie temperature Tcs is 350 degreeC and Curie temperature Tcm is 300 degreeC. The recording layer 8 is a magnetic film having a transition metal magnetization dominance like the medium A and the medium D. In the medium F, other film forming methods, film forming conditions, thicknesses, and the like are the same as those of the medium A and the medium D.

In the case where the recording layer 8 is a magnetic film of rare earth dominant magnetization, the recording auxiliary layer 3 is made of a magnetic film of rare earth dominant magnetization, and the Curie temperature Tcs of the recording auxiliary layer 3 is recorded. Even when the Curie temperature Tcm is higher than the Curie temperature, the shift of the magnetic domain (mark) at the time of recording can be reduced.

The case where the magnetization shown by the arrow exists in the area | region (mark boundary) 8a1, 8a2 of the recording layer 8 at the time of recording in the case where mark length Lm is long (FIG. 15 (a)) is shown. In the recording auxiliary layer 3, there are regions 3a1 and 3a2 corresponding to the regions 8a1 and 8a2. Since the region 8b1 is equal to or more than the Curie temperature Tcm, the magnetization disappears, and correspondingly, the magnetization of the region 3b1 is also disappeared. In addition, since the Curie temperature Tcs and the Curie temperature Tcm are different from each other between the boundary of each region of the recording layer 8 and the region of the recording auxiliary layer 3, a deviation occurs due to the difference of the Curie temperature.

In this state, if there is no recording auxiliary layer 3, when the mark is to be recorded in the area 8b1, the recording magnetic field applied from the magnetic head (not shown) is lost by the semi-magnetic field Hmra. Then, the position (region 8b1) of the recording mark is shifted. However, since the region 3a2 corresponding to the region 8a2 exists here, the magnetic field Hssa by the region 3a2 functions to eliminate the semi-magnetic field Hmra, so that the shift of the position of the recording mark can be prevented.

FIG. 15 shows a case where the magnetization indicated by the arrow exists in the region (mark boundary: 8a3, 8a4, 8a5, 8a6) of the recording layer 8 during recording when the mark length Lm is short (Fig. 15 (b)). . In the recording auxiliary layer 3, there are regions 3a3, 3a4, 3a5 and 3a6 corresponding to the regions 8a3, 8a4, 8a5 and 8a6. Since the region 8b2 is equal to or more than the Curie temperature Tcm, the magnetization disappears, and correspondingly, the magnetization of the region 3b2 is also disappeared.

In this state, if there is no recording auxiliary layer 3, the boundary portion of the region 8b2 is magnetized by the semi-magnetic Hmrb generated by the magnetization of the region 8a6, and the position of the recording mark is shifted. However, here, since the area 3a6 corresponding to the area 8a6 exists, the magnetic field Hssb by the area 3a6 functions to eliminate the semi-magnetic field Hmrb, thereby preventing the shift of the position of the recording mark. .

By properly adjusting the difference between the Curie temperature Tcm and the Curie temperature Tcs, it is possible to cause the magnetic field Hssa to occur according to the semi-magnetic Hmra when the mark length Lm is long. May occur. That is, in either case of the long or short mark length Lm, the influence of the semi-magnetic field by the recording layer 8 can be reduced, and the shift of the mark can be prevented.

At the time of reproduction, since the recording auxiliary layer 3 and the recording layer 8 are magnetically divided by the nucleation layer 5, the magnetization state of the recording auxiliary layer 3 is not reproduced.

As in the case of the medium F, in the method of adjusting the difference between the Curie temperature Tcm and the Curie temperature Tcs using the composition of the recording auxiliary layer 3 as a magnetic film having the same magnetization dominance as the recording layer 8, the recording layer 8 It is difficult to finely adjust the size of the magnetization by the recording auxiliary layer 3 for eliminating the semi-magnetic field.

Fig. 16 is a schematic diagram illustrating the operation of the recording auxiliary layer in the magneto-optical recording medium (medium G) according to the second embodiment of the present invention. By lowering the recording resolution of the recording auxiliary layer 3, it becomes possible to finely adjust the size of the magnetization by the recording auxiliary layer 3 for eliminating the semi-magnetic field of the recording layer 8. A medium for reducing the recording resolution of such a recording auxiliary layer 3 is referred to as medium G. The recording resolution of the recording auxiliary layer 3 can be controlled by changing the gas pressure of the film forming conditions of the recording auxiliary layer 3, so that it is relatively easy to adjust. The medium G was made the same structure as the medium F, and the gas pressure of the film forming conditions of the recording auxiliary layer 3 was enlarged from 0.5 Pa to 1.5 Pa in the case of medium F (medium D, medium A).

FIG. 16 shows the same state as in FIG. 15A. The recording layer 8 is the same as the medium F, and the boundary of the regions 8a1, 8a2, and 8b1 is viewed from the surface 8s side. The magnetization directions of the regions 8a1 and 8a2 in FIG. 15A are shown as AM1 and AM2 when viewed from the surface 8s side. The boundary of the area | region 3a1, 3a2, 3b1 shows the case seen from the surface 3s side. The vertical curve shows that the boundary of each area is entangled with each other and the recording resolution of the recording auxiliary layer 3 is lowered. The magnetization directions of the regions 3a1 and 3a2 in FIG. 15A are shown as AM3 and AM4 when viewed from the surface 3s side.

17 is a graph showing mark length-jitter characteristics of the media C, F, and G. FIG. Mark length (unit: mm) is shown on the horizontal axis, and random jitter (unit:%) is shown on the vertical axis. The medium F in which the Curie temperature Tcs of the recording auxiliary layer 3 is higher than the Curie temperature Tcm of the recording layer 8 and the medium G in which the recording resolution of the recording auxiliary layer 3 is reduced also affect the operation of the recording auxiliary layer 3. This improves random jitter at each mark length.

(Third Embodiment)

FIG. 18 is a schematic diagram showing a laminated structure of a RAD system magneto-optical recording medium (medium H) according to the third embodiment of the present invention. RAD stands for Rear Aperture Detection Resolution, and there is a Japanese Patent Application Laid-open No. Hei 4-271039 as a document which discloses this kind of technology.

The medium H is, on the substrate 1, the reflective layer 2, the recording auxiliary layer 3, the nucleation base layer 4, the first nucleation layer 5, the second nucleation layer 6, and the recording layer 8 ), The intermediate layer 9, the regeneration layer 12, the protective layer 13 and the coat layer 14 is a laminated structure formed in this order. That is, the recording auxiliary layer 3, the nucleation base layer 4, the first nucleation layer 5, and the second nucleation layer 6 are added to the conventional RAD magneto-optical recording medium. The intermediate layer 9 and the reproduction layer 12 are added to the structure of the medium A (FIG. 4), and the front illumination system is similar to that of FIG. 4 and the detailed description is omitted.

Each layer structure of the medium H is basically the same as the medium A, and details thereof are omitted. The main configuration is as follows.

Recording auxiliary layer (3): GdFeCo (Gd25: Fe49: Co26) Rare earth magnetization dominance magnetic film (The recording layer 8 is transition metal magnetization dominance, so it is referred to as rare earth magnetization dominance.)

Nucleation base layer 4: SiN film, thickness 0.5nm

First nucleation layer 5: Cr film, 0.5 nm thick

2nd nucleation layer 6: C film, thickness 0.5nm

Recording layer 8: TbFeCo (Tb22: Fe60: Co18) transition metal magnetization dominant magnetic film

Intermediate layer (9): GdFeCoSi (Gd30: Fe60: Co2: Si8) magnetic film

Regenerated layer 12: GdFeCo (Gd24: Fe63: Co13)

Each layer film forming condition of the magnetic film medium H is basically the same as the medium A, and the following points are different from each other. This condition also varies depending on the device and the like, and is not limited thereto, and can be changed as necessary.

Intermediate layer 9: Sputter film-forming by mounting a Si chip on the alloy target of GdFeCo. Gas pressure is 0.54 Pa, and input power is 500 W.

Regeneration layer 12: Sputter film deposition of the alloy target of GdFeCo. Gas pressure is 0.86Pa, input power is 800W.

19 is a schematic diagram showing a laminated structure of a conventional RAD system magneto-optical recording medium (medium I). The medium I is configured to exclude the recording auxiliary layer 3, the nucleation base layer 4, the first nucleation layer 5, and the second nucleation layer 6 from the medium H, and the deposition conditions and the like are the same as those of the medium H. Do.

In the medium H, since the recording layer 8 is a magnetic film of transition metal magnetization dominance, the recording auxiliary layer 3 is made of a rare earth magnetization dominance magnetic film, but the recording auxiliary layer 3 is a magnetic film of transition metal magnetization dominance. Even with this, there is an effect of reducing the shift of the mark during recording. This reason is as described in FIG. The medium in which the recording auxiliary layer 3 is made of the magnetic film of the transition metal magnetization dominance like the recording layer 8 is referred to as the medium J. The Curie temperature Tcs of the recording auxiliary layer 3 is set to 350 ° C, and is higher than the Curie temperature Tcm300 ° C of the recording layer 3.

 In the medium H, the gas pressure when the recording auxiliary layer 3 is formed is 0.5 Pa. In the medium J, the gas pressure when the recording auxiliary layer 3 is formed is 1.0 Pa, which is higher than that in the medium H. It was. This gas pressure is appropriately selected and determined so that random jitter is minimized. As a result, the resolution of the recording auxiliary layer 3 decreases and the shift of the recording mark can be reduced as described with reference to FIG. 16.

20 is a chart for comparing the characteristics of the media H, I, and J. FIG. For the media H, I, and J, the recording layer coercive force Hc (kOe), the mark length is 0.20 µm, and the CNR (㏈) and the random jitter (%) for 0.15 µm. With respect to the medium I, the mediums H and J are improved in any of the recording layer coercivity Hc, CNR, and random jitter. That is, the recording layer coercive force Hc increases by the effect of the 1st nucleation layer 5 and the 2nd nucleation layer 6, and the CNR at the time of short mark recording is greatly improved. In addition, due to the effect of the recording auxiliary layer 3, the recording magnetic field is reduced, and the random jitter at the short mark is greatly improved.

When the medium H and the medium J are compared, since the recording auxiliary layer 3 of the medium J has been changed (improved), the random jitter of the medium J is further improved.

(Example 4)

Fig. 21 is a schematic diagram showing the laminated structure of the DWDD-type magneto-optical recording medium (the medium K) according to the fourth embodiment of the present invention. Fig. 22 is a schematic diagram showing a laminated structure of a conventional DWDD-type magneto-optical recording medium (medium L). In addition, DWDD stands for Domain Wall Displacement Detection, and Japanese Patent Laid-Open No. 1-43041 is a document which discloses this kind of technology. In addition, the medium L corresponds to the front illumination scheme of the conventional DWDD.

The medium K is formed on the substrate 1, on the reflective layer 2, the recording auxiliary layer 3, the nucleation base layer 4, the first nucleation layer 5, the second nucleation layer 6, and the recording layer 8 The switching layer 10, the control layer 11, the regeneration layer 12, the protective layer 13, and the coat layer 14 are laminated structures formed in this order. The medium L is a reflective layer 2, a dielectric layer 7, a recording layer 8, a switching layer 10, a control layer 11, a reproduction layer 12, a protective layer 13 and a coating on the substrate 1 The layer 14 is a laminated structure formed in this order. Since the nucleation base layer 4 of the medium K corresponds to the dielectric layer 7 of the medium L, the medium K is the recording auxiliary layer 3 and the first nucleus with respect to the conventional DWDD type magneto-optical recording medium (medium L). The formation layer 5 and the 2nd nucleation layer 6 were added, and the thing corresponding to the front illumination system is the same as FIG. 18 etc., and detailed description is abbreviate | omitted.

The structure of each layer of the medium K is basically the same as that of the mediums A and H, and details are omitted. The main configuration is as follows.

Recording auxiliary layer 3: GdFeCo (Gd23: Fe51: Co26) magnetic film.

Since the recording layer 8 is a magnetic film of the rare earth magnetization dominance, the recording layer 8 is a magnetic film of the transition metal magnetization dominance.

Nucleation base layer 4: SiN film, thickness 0.5nm

First nucleation layer 5: Cr film, 0.5 nm thick

2nd nucleation layer 6: C film, thickness 0.5nm

Recording layer 8: TbFeCo (Tb24: Fe56: Co20) magnetic film

Switching layer 10: TbFeCo (Tb18: Fe80: Co2) magnetic film

Control layer 11: TbFeCo (Tb19: Fe74: Co7)

Magnetic film regeneration layer 12: GdFeCo (Gd25: Fe65: Co10)

The film-forming conditions of each layer of the magnetic film medium K are basically the same as those of the mediums A and H, and the following points are different from each other. This condition also varies depending on the device and the like, and is not limited thereto, and can be changed as necessary.

Switching layer 10: Sputter | spatter film-forming by mounting Co chip on the alloy target of TbFe. Gas pressure is 0.5 Pa, input power is 500 W.

Control layer 11: Sputter film deposition of the alloy target of TbFeCo. Gas pressure is 0.8 Pa, input power is 800 W.

The film forming conditions and the like of the medium L are the same as the medium K.

In the medium L, a dielectric layer 7 is formed between the reflective layer 2 and the recording layer 8. Since the heat dissipation property can be further controlled by the dielectric layer 7, better marks are recorded. As described above, the nucleation base layer 4 of the medium K adjusts the surface tension so that formation of the nuclei 5a and 6a is appropriate in addition to the control of the heat dissipation.

In the medium K, since the recording layer 8 is a magnetic film of the rare earth magnetization dominance, the recording auxiliary layer 3 is a magnetic film of the transition metal magnetization dominance, but the recording auxiliary layer 3 is of the magnetic film of the rare earth magnetization dominance. Also, there is an effect of reducing the shift of the mark during recording. This reason is as described in FIG. A medium in which the recording auxiliary layer 3 is made of the magnetic film of the rare earth magnetization dominance like the recording layer 8 is referred to as the medium M. The Curie temperature Tcs of the recording auxiliary layer 3 is set to 350 ° C, and is higher than the Curie temperature Tcm300 ° C of the recording layer 3.

Further, in the medium K, the gas pressure when the recording auxiliary layer 3 is formed is 0.5 Pa. In the medium M, the gas pressure when the recording auxiliary layer 3 is formed is 1.0 Pa, which is higher than that in the medium K. It was. As a result, the resolution of the recording auxiliary layer 3 decreases and the shift of the recording mark can be reduced as described with reference to FIG. 16.

 23 is a chart comparing the characteristics of the media K, L, and M. FIG. For the media L, K and M, the recording layer coercive force Hc (kOe), the mark length is 0.12 占 퐉, the CNR (㏈) for 0.10 占 퐉, the mark length is 0.15 占 퐉, and the random jitter (%) for 0.10 占 퐉. With respect to the medium L, the mediums K and M are improved in any of the recording layer coercive force Hc, CNR, and random jitter. That is, the recording layer coercive force Hc increases by the effect of the 1st nucleation layer 5 and the 2nd nucleation layer 6, and the CNR at the time of short mark recording is improved. In addition, due to the effect of the recording auxiliary layer 3, the recording magnetic field is reduced, and the random jitter at the short mark is greatly improved.

When the medium K and the medium M are compared, since the recording auxiliary layer 3 of the medium M has been changed (improved), the random jitter of the medium M is further improved.

(Example 5)

24 is a schematic diagram showing the laminated structure of the phase change type optical recording medium (medium N) according to the fifth embodiment of the present invention. Corresponding to the front illumination method is the same as in FIG. 4 and the like, and detailed description is omitted. In addition, the present invention can also be applied to a conventional optical recording medium in which the structure is formed in a reverse order to form a laminated structure and is recorded over a substrate.

The medium N is a reflective layer 2, a nucleation base layer 4, a first nucleation layer 5, a second nucleation layer 6, a recording layer 8, and a protective layer 13 on the substrate 1. And the coat layer 14 is a laminated structure formed in this order.

Each layer structure of the medium N is basically the same as the medium A, and only the recording layer 8 is different. The configuration of the recording layer 8, film formation conditions, and the like are as follows.

Recording layer 8: Phase change film of GeSbTe (Ge70: Sb21: Te: 9). The phase change film formed here is a film | membrane in which the reflectance in a crystalline state and an amorphous state differs, for example. Sputter film deposition of the alloy target of a predetermined composition. The gas (Ar) pressure is 0.5 Pa and the input power is 500 W.

In order to compare the characteristics with the medium N, an optical recording medium having a conventional structure (hereinafter referred to as medium P) was created. The medium P is the same structure as the magneto-optical recording medium of FIG. 1, except for the nucleation base layer 4, the first nucleation layer 5, and the second nucleation layer 6 in the medium N. In addition, like other media, the front illumination method.

25 is a chart for comparing the characteristics of the media N, P. FIG. In the medium N, by forming the nucleation layer (the first nucleation layer 5 and the second nucleation layer 6), the random jitter is greatly improved especially at a short mark length.

(Example 6)

26 is a block diagram showing an outline of an information recording / reproducing apparatus according to a sixth embodiment of the present invention. Although the case where the magneto-optical recording and reproducing apparatus 30 is used as the information recording / reproducing apparatus is described, it is similarly applicable to the optical recording / reproducing apparatus.

The spindle motor 31 rotates the magneto-optical recording medium 32 (hereinafter referred to as the medium 32) according to the present invention at a predetermined rotational speed. The laser beam is irradiated onto the medium 32 from the laser diode 33. The laser light becomes parallel light by the collimated lens 34, passes through the beam splitter 35, is collected by the objective lens 36, and controlled to connect the focus on the recording film of the medium 32. . The laser diode 33 is adjusted so that a high level light output and a low level light output are output by pulse modulation means (not shown) in the laser drive means 37.

In recording the information, the laser light is modulated into a pulse shape by pulse modulation means in accordance with the information to be recorded, and irradiated to the medium 32. Then, the bias magnetic field applying means 39 is applied to the vicinity of the laser spot formed in the surface portion of the medium 32 by irradiation of the laser light controlled for recording, for example, in the upward direction in the drawing. Information can be recorded by applying a direct current magnetic field of magnitude. In addition, the bias magnetic field applying means 39 is controlled by the controller 38.

At the time of erasing the information, for example, by applying a magnetic field in the downward direction to the near side of the laser spot formed in the surface portion of the medium 32 by irradiation of the laser light controlled for erasing, Can be erased.

At the time of reproduction, the controller 38 drives the laser diode 33 directly through the laser drive means 37 to irradiate the laser light, and applies a regenerating magnetic field in the same direction as at the time of recording. The temperature distribution is generated in the surface portion of the medium 32 by the irradiation of the laser light controlled for regeneration. By this temperature distribution, a mask area | region and an opening area | region are formed, and the reflected light is obtained from an opening area | region. The reflected light is guided to the lens 40 by changing the optical path by the beam splitter 35. The lens 40 collects the reflected light and guides it to the photodetector 41. By detecting the collected reflected light by the photodetector 41 and performing signal processing by the controller 38, the recorded information can be reproduced with a good CNR.

In the case of the front illumination system, the bias magnetic field applying means 39 is disposed between the medium 32 and the objective lens 36 so that the laser spot is focused on the surface of the medium 32.

(Example 7)

27 is a diagram showing an outline of a magnetic recording apparatus according to the seventh embodiment of the present invention.

The spindle 51 rotates the recording medium (magnetic recording medium) 52 according to the present invention at a predetermined rotational speed. The laser light is irradiated from the laser diode 53 onto the recording layer 68 formed on the surface of the recording medium 52. The laser light becomes parallel light by the collimating lens 54, passes through the beam splitter 55, is collected by the objective lens 56 mounted on the optical head slider 58, and is recorded on the recording layer 68. It is controlled to connect the focus. The laser diode 53 is pulse-modulated by the laser drive circuit 63 to enable high level light output and low level light output.

At the time of recording the information, the laser light is modulated into a pulse shape by the laser drive circuit 63 according to the information to be recorded, and irradiated to the recording layer 68. In the vicinity of the laser spot formed on the surface of the recording layer 68 by the irradiation of the laser light controlled for recording, the recording coil 59 is used to generate a direct current magnetic field having a predetermined size in the upward direction. By applying the information of the upward magnetic field and applying the downward magnetic field, the information of the downward magnetic field can be recorded as the magnetic domain. By making the recording coil 59 close to the recording layer 68, it becomes possible to make the recording coil 59 very small. By making the recording coil 59 sufficiently small, magnetic field modulation recording becomes possible. In addition, the recording coil 59 is controlled by the recording coil drive circuit 67. The optical head slider 58, the recording coil 59, and the like constitute a magneto-optical recording unit.

In addition, the light reflected by the recording layer is changed by the beam splitter 55 to an optical path on the right side in the drawing and converted into an electric signal by the photo detector 64 so that the focus direction is detected by the focus signal detection circuit 65. . The focusing coil drive circuit 66 is controlled by the focusing direction detected by the focus signal detecting circuit 65, and a focus current flows to the focusing coil 57, thereby operating the objective lens 56 up and down in the drawing. The laser spot is controlled to focus on the recording layer 68.

On the other hand, during regeneration, the magnetic domain change is detected by the magnetic regeneration element 60, which is an element that detects the magnetic flux mounted on the magnetic head slider 61 (the magnetic flux of the magnetic domain), and the regeneration element drive detection circuit 62 ), Information recorded with high density can be reproduced with good CNR. The magnetic regeneration element 60, the magnetic head slider 61, and the like constitute a magnetic regeneration portion.

The configuration of the recording medium (magnetic recording medium) 52 according to the seventh embodiment of the present invention is as follows. A heat diffusion layer, a nucleation layer (having irregularities on the surface on the recording layer side), a recording layer (having vertical magnetic anisotropy), a protective layer, and a lubricating layer are formed on the substrate. Here, since the heat diffusion layer adjusts heat generated by the irradiated light, the heat diffusion layer basically plays a role similar to that of the reflective layer described in the sixth embodiment.

Next, the manufacturing method of this recording medium 52 is demonstrated.

The disk diameter was set to 2.5 inches using the flat (uniform) glass substrate for the board | substrate. As the heat diffusion layer, a metal or an alloy-based material can be used. Here, the film thickness is 40 nm in the AlSi (Al ₆ O: Si ₄ O) composition. A nucleation layer was formed thereon. The nucleation layer had a two-layer structure, firstly formed RuO by 1 nm, and then formed Ag by 1 nm. As the recording layer, 25 nm of TbFeCo (Tb ₂ l: Fe ₄ O: Co39) was formed as a single layer film. 3 nm of SiN, 1 nm of Cr, and 1 nm of C were formed in the protective layer. These layers were formed by the normal magnetron sputtering method. In addition, each layer used the target of each material, and Ar was used for the sputter gas. In addition, RuO was formed by a reactive sputter with a mixed gas of Ar and oxygen (O 2) using a Ru target. SiN was also formed by a reactive sputter with a mixed gas of Ar and nitrogen (N ₂ ) using a Si target. The lubricant was applied to the surface of the recording medium 52 thus produced. As a lubricating material, it applied by the spin coating method using fluorine-type resin. The film thickness of this lubricant is 1 nm or less.

28 shows an example of the change in the coercivity with respect to the temperature of the recording medium 52 thus formed and the saturation magnetization. The coercive force at room temperature is 10 kOe or more, but as the temperature increases, as shown by the solid line in the drawing, the coercive force at 10 kOe or more at room temperature becomes small and becomes zero at approximately 350 ° C. When heating to a temperature that becomes a recordable coercivity by the recording magnetic field generated by the recording coil 59 mounted on the optical slider 58, recording becomes possible.

In addition, since the saturation magnetization value at room temperature of the recording medium 52 is 100 emu / cc or more, as indicated by the dotted line in the figure, the magnetic flux from the recorded mark can be reproduced by a normal magnetoresistive element.

An information recording / reproducing method will be described with reference to FIG. 27. Recording is performed (recording magnetic domain) by applying a magnetic field in a state in which the recording medium 52 is heated by light irradiation to lower the coercive force of the recording layer. Then, the signal is reproduced by detecting the leaked magnetic flux from the recorded magnetic domain.

First, in order to confirm the principle experiment, a small air core coil (recording coil 59) was formed in the floating slider (optical head slider 58), and light was incident from the air core portion. By irradiating light, the coercive force of the recording medium 52 is lowered, so that a current flows through the air core coil in that state to generate a magnetic field. This magnetic field changes the direction of the magnetic flux upward and downward in accordance with the size of the magnetic domain to be recorded. In order to detect the magnetic flux, a magnetic regeneration head (magnetic head slider 61) was used. The magnetic regeneration head is a magnetoresistive element (magnetic regeneration element 60) attached to the slider.

Fig. 29 shows the change of the CNR with respect to the laser recording power of the magnetic recording medium of the present invention. Here, the recording magnetic field was set to 400 esters. In addition, the size of the recorded mark is 50 nm. The regenerated core width of the used magnetic regeneration head was 0.2 占 퐉 and the shield gap length was 0.09 占 퐉. The wavelength of the recording laser is 405 nm, and the numerical aperture NA of the objective lens is 0.85.

As shown by the solid line in FIG. 29, the reproduction characteristics are almost saturated by setting the laser recording power to 15 kW. It can be seen that, by magnetic regeneration, even such minute marks can be reproduced, and the reproducing characteristic is greatly improved rather than reproducing thermomagnetic recording with light.

(Example 8)

In the seventh embodiment, an AlSi film was used as the heat diffusion layer. In practice, however, a soft magnetic film may be used here. The reason is that the thermal conductivity of metals and alloys varies depending on the material, but the value is much larger than that of the dielectric. In addition, since the magnetic field of the recording coil concentrates on the recording film by using the soft magnetic film, a large magnetic field can be obtained. This example is explained. The medium and measurement system are almost the same as in the seventh embodiment.

Here, CoZrNb, FeCSi and NiFe were used as the soft magnetic film, and the film thickness was 80 nm. The change in the CNR with respect to the laser recording power of these recording media (magnetic recording media) is shown by a dotted line in FIG. Since the thermal conductivity of the soft magnetic film is smaller than that of AlSi, it can be seen that recording can be performed with low power. In addition, CNR is expected to increase to the same extent as AlSi, but slightly. This has a great effect by making the magnetic field on a medium large.

(Example 9)

30 is a configuration diagram showing an integrated head used for recording / reproducing of the magnetic recording apparatus of the present invention. An integrated head incorporating an optical system (laser light irradiating portion: composed of an optical aperture 74, a waveguide 75, an optical inlet 81, etc.), a recording coil 79, and a magnetic reproducing element (magnetic resistance element: 77) The form in which 71H) is mounted on one slider 70 is shown. The optical system used the waveguide type. The recording coil 79 was formed on the back side of the light opening 74 from which light irradiated onto the recording medium (magnetic recording medium) is emitted. This is because, when the recording medium rotates at a high speed, the point where the temperature actually rises is shifted later than the spot position. The magnetoresistive element 77 for detecting the magnetic flux was formed between the light opening 74 and the recording coil 79.

FIG. 30A illustrates a state in which the integrated head 71H is mounted on an end portion of the slider substrate 71 constituting the slider 70.

FIG. 30B is a view seen from the arrow B direction in FIG. 30A. That is, the figure seen from the slider surface (the surface opposing a recording medium). AlTiC was used for the slider substrate 71. The slider substrate 71 has shown the state extracted from one wafer. A part of the planarization layer 72 was formed on the surface of the slider substrate 71 for a basis. Thereafter, Au to be used for the light shield portion 73 is deposited. This film thickness is 100 nm. By photolithography techniques (processes using resist and etching), the lower surface of the light shield portion 73 is patterned. On it, a portion corresponding to the light opening 74 and other unnecessary portions are masked with a resist to deposit Au. Thereafter, the resist was removed by the lift-off method or the like to form the light opening 74 and the light shield portion 73. The width of the light opening 74 formed in this manner is 100 nm in the width direction and 60 nm in the height direction in the drawing, and the light shield portion 73 is 50 nm thick with respect to the waveguide 75.

Alumina was formed on the light shield portion 73 by the sputtering method, and polished so as to be a plane to form a planarization layer 72. After the 200 nm-thick permalloy (first shield layer 76) was formed on the planarization layer 72, the magnetoresistive element 77 as an element which detects a magnetic flux while patterning by the photolithography technique was formed. 200 nm of FeCo (second shield layer 78) was formed thereon. Further, a resist of 1 mu m was formed, and a recording coil 79 and a recording magnetic pole 80 were formed thereon. The size of the recording magnetic pole 80 was made width = 100 nm and height = 50 nm. The recording coil 79 and the recording magnetic pole 80 serve as elements for applying a magnetic field to the recording medium.

FIG. 30C is a view seen from the arrow C direction in FIG. 30A. That is, the side view of the integrated head 71H is shown. FIG. 30B shows a recording coil 79 that is difficult to show. Here, the second shield layer 78 and the recording magnetic pole 80 are connected to FeCo in the up-down direction (up-down direction in (B). There is no. In addition, the light introduction port 81 guides the laser light from the outside of the slider 70 via an optical fiber or the like, and irradiates (applies) light to the recording medium from the light opening 74.

In this way, the recording / reproducing characteristics were examined by the test-produced integrated head 71H. Fig. 31 is a graph showing the CNR characteristics with respect to the recording current of the magnetic recording medium of the present invention. The measured mark length is 50 nm. Here, as a recording medium (magnetic recording medium), a soft magnetic film is used for the heat diffusion layer. Since the magnetic flux emitted from the recording magnetic pole 80 passes through the soft magnetic film and returns to the second shield layer 78, the magnetic field for the magnetic domain to be recorded is increased.

According to the above-described configuration, even a low laser recording power can be recorded. The recording current Iw (current flowing through the recording coil) at the time of recording was set to 20 mA. In addition, the sensing current Is flowing to the magnetoresistive element 77 was 3 mA. These are about the values used for normal magnetic recording.

In the figure, the solid line shows the CNR characteristic when a nonmagnetic layer is used for the heat diffusion layer, and the dotted line shows the CNR characteristic when a soft magnetic film is used for the heat diffusion layer. As is clear from the figure, the soft magnetic film used in the heat diffusion layer has a high CNR characteristic due to the less write current.

(Example 10)

32 is a chart showing CNR characteristics of the base layer structure of the magnetic recording medium used in the present invention. Here, in order to confirm the effect of the base layer (nucleation layer), a recording medium (self-recording medium) having variously changed the base layer was produced and evaluated for characteristics. Although the basic manufacturing method was as above-mentioned, the sample of the following structure was produced.

Substrate / heat diffusion layer (soft magnetic film: 100 nm) / base layer (nucleation layer) / recording layer (20 nm) / protective layer (5 nm). TbFeCo (Tb19: Fe50: Co31) was used for the recording layer. The base layer was investigated using only SiN, and using an example of the material described in the claims as a feature of the present invention. 32 is shown as samples 30-40.

As the head for recording / reproducing, the integrated head of the ninth embodiment was used. In the evaluation of the recording / reproduction, the CNR for the mark length ML of 50 nm was examined. The result is shown in FIG. The two-layer structure of the base layer material is a layer close to the heat diffusion layer. From this result, it turned out that it is effective to use a nucleation layer for a base layer. The recording current is a current flowing through the recording coil.

Since the optical recording medium and the magneto-optical recording medium of the present invention have good random jitter characteristics and CNR, and can also reduce the recording magnetic field, it is possible to provide an information recording medium capable of high density.

Claims (18)

A reflective layer and a recording layer are formed in this order on a substrate, and an optical recording medium for recording / reproducing information by irradiating light from the recording layer side, wherein a nucleation layer having irregularities on its surface is formed between the reflective layer and the recording layer. And an optical recording medium. The method of claim 1, The nucleation layer is one selected from the group consisting of W, Mo, Ta, Fe, Co, Ni, Cr, Pt, Ti, P, Au, Cu, Al, Ag, Si, Gd, Tb, Nd, and Pd An optical recording medium formed from a material containing two or more elements. delete The method according to claim 1 or 2, The nucleation layer is formed in plural layers, and the surface tension of the nucleation layer formed on the recording layer side is stronger than the surface tension of the nucleation layer formed on the reflection layer side. delete A reflective layer and a recording layer having perpendicular magnetic anisotropy are formed in this order on a substrate, and a magneto-optical recording medium for recording / reproducing information by irradiating light from the recording layer side, comprising: a nucleation layer having irregularities on its surface and the reflective layer; It is provided with the recording layer, The magneto-optical recording medium characterized by the above-mentioned. The method of claim 6, The nucleation layer is 1 or 2 selected from the group consisting of W, Mo, Ta, Fe, Co, Ni, Cr, Pt, Ti, P, Au, Cu, Al, Ag, Si, Gd, Tb, Nd, and Pd The magneto-optical recording medium formed of a material containing the above elements. delete delete The method according to claim 6 or 7, And a recording auxiliary layer having perpendicular magnetic anisotropy between the reflective layer and the nucleation layer in order to eliminate the semi-magnetic field generated by the magnetization of the recording layer. delete delete delete delete delete On the substrate, a heat diffusion layer and a recording layer having perpendicular magnetic anisotropy are formed in this order, and information is recorded / reproduced by irradiating light from the recording layer side, and formed between the heat diffusion layer and the recording layer to the surface. An information recording / reproducing method using a magnetic recording medium having a nucleation layer having irregularities, the optical recording method being performed by applying light and a magnetic field to the magnetic recording medium, and detecting magnetic flux on the recording layer side to generate magnetic information. An information recording / reproducing method, characterized by reproducing. On the substrate, a heat diffusion layer and a recording layer having perpendicular magnetic anisotropy are formed in this order, and information is recorded / reproduced by irradiating light from the recording layer side, and formed between the heat diffusion layer and the recording layer to the surface. A magnetic recording medium having a nucleation layer having irregularities, an optical magnetic recording unit for recording information by applying light and a magnetic field to the magnetic recording medium, and a magnetic reproducing unit for reproducing information by detecting magnetic flux from the recording layer side. Magnetic recording apparatus characterized in that it has. The method of claim 17, And a slider on which an element for applying the light to heat the magnetic recording medium, an element for applying the magnetic field, and an element for detecting the magnetic flux are mounted.

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