JP4161537B2 - Manufacturing method of optical recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical information recording / reproducing medium (optical recording medium) used in a rewritable optical information recording / reproducing apparatus or the like by laser light irradiation. At least a recording layer and a light transmission layer are sequentially formed on a substrate. Thus, the present invention relates to an optical information recording / reproducing medium of a type in which laser light is incident from the light transmitting layer side and information is recorded / reproduced on / from the recording layer of the recording medium, and a method for manufacturing the same.
[0002]
[Prior art]
At present, an optical information recording method using a laser beam is practically used in various places as a large-capacity memory because a large-capacity information can be accessed without contact and at a high speed. Optical information recording / reproducing media using an optical information recording / reproducing method include a read-only type known as a compact disc and a laser disc, a write-once type that can be recorded by the user, and a user that can repeatedly record and reproduce It is classified as a rewritable type. Write-once and rewritable optical information recording / reproducing media are being used as external memory of computers, documents, and image files. The rewritable optical information recording / reproducing medium includes a phase change type optical disk that utilizes a phase change of a recording film and a magneto-optical disk that utilizes a change in the magnetization direction of a perpendicular magnetic film. Of these, the phase-change type optical disc does not require an external magnetic field like the magneto-optical disc when recording information, and can easily overwrite or overwrite the recorded information. It is expected to become the mainstream of formula information recording / reproducing media.
[0003]
Conventionally, a rewritable phase change type optical disk using a phase change between a crystal and an amorphous layer of a recording film by laser light irradiation is known. In a phase change optical disc, recording is performed by irradiating a recording film with high-power laser light and locally raising the recording film temperature, thereby causing a phase change between the crystal and the amorphous of the recording film. Reproduction of recorded information is performed by irradiating a laser beam having a relatively low power compared with the time of recording and detecting a change in optical constant of the information recording unit as a reflected light intensity difference.
[0004]
As the recording film of the phase change optical disc, a chalcogenide-based material such as GeSbTe, InSbTe, or AgInSbTe is used. These recording films are all formed by a film forming method such as resistance heating vacuum deposition, electron beam vacuum deposition, or sputtering. The state of the recording film immediately after film formation is a kind of amorphous state, and recording is performed on this recording film to form an amorphous recording portion. Processing is performed. Recording is accomplished by forming an amorphous portion in this crystallized state.
[0005]
A general phase change type optical disk recording / reproducing method performs crystallization or amorphization by changing the power of laser light between two levels. That is, at the time of recording, the recording film is irradiated with a laser beam having a power capable of raising the temperature of the recording film to the melting point or more, and the irradiated portion becomes amorphous when cooled. In the case of erasing information, a laser beam having a power such that the temperature of the recording film reaches a temperature not lower than the crystallization temperature and not higher than the melting point is irradiated. Reproduction is read as a reflected light intensity difference by irradiating a low-power laser beam.
[0006]
The recording film constituting the above-described phase change optical disk is formed on a transparent disk substrate on which spiral or concentric guide grooves, that is, recording tracks (land portions: concave portions and groove portions: convex portions) are previously arranged. . By this recording track, laser light emitted from the optical head of the information recording / reproducing apparatus is guided along the information string. The recording track has alternating concave and convex shapes. When viewed from the optical head, a concave shape, that is, a far side is referred to as a land portion, and conversely, a convex shape, that is, a near side is referred to as a groove portion. The distance from the center of the land or groove to the center of the adjacent land or groove is called the track pitch.
[0007]
In order to form a phase change optical disk medium using the recording film and the substrate described above, a first dielectric layer, a recording film, and a second dielectric layer are sequentially disposed on the transparent disk substrate. Alternatively, a first dielectric layer, a recording film, a second dielectric layer, a reflective film, and the like are sequentially disposed on the transparent disk substrate, or the first dielectric layer and the second dielectric layer are disposed on the transparent disk substrate. In general, a dielectric layer, a recording film, a third dielectric layer, a reflective film, and the like are sequentially disposed.
[0008]
In the above-described phase change type optical disc medium, usually, laser light is incident from the above-described transparent disc substrate side, and information is recorded on and reproduced from the recording film.
[0009]
In recent years, with the demand for higher recording density, information is recorded on both the track pitch of the recording track and the concave portion (land portion) of the guide groove and the convex portion (groove portion) between the land portions. Land / groove recording is generally performed. At the same time, in order to improve the recording density, the spot diameter of the laser beam is miniaturized.
[0010]
Since the laser beam spot diameter described above depends on λ / NA of the recording / reproducing system (λ: wavelength of the laser beam, NA: numerical aperture of the objective lens), the wavelength of the laser beam is shortened to reduce the aperture of the objective lens. By increasing the number, the spot diameter of the laser beam is reduced, and the recording density can be increased.
[0011]
However, when the numerical aperture of the objective lens is increased, coma aberration increases, and there is a concern that signal quality is deteriorated. The coma aberration is an amount proportional to the product of the skew angle (tilt angle with respect to the optical axis of the disk), the thickness of the transparent substrate through which the laser light passes, and the third power of the numerical aperture of the objective lens. Therefore, a method for reducing the thickness of the transparent substrate through which the laser beam passes has been proposed as one means for suppressing the coma aberration.
[0012]
As described above, as a method of reducing the thickness of the transparent substrate through which the laser beam passes, a method of changing the thickness of the transparent substrate itself from the normally used thickness of 0.6 mm to 0.3 mm is also discussed. However, since the thickness of the resin substrate having a thickness of 0.3 mm is thin, it is difficult to satisfy the desired mechanical properties because the substrate is bent when the concave and convex grooves for guiding the laser beam are formed.
[0013]
From such a situation, as another method capable of achieving the same function as reducing the thickness of the transparent substrate through which the laser beam passes, on a transparent resin substrate having a normal thickness of 0.6 mm to 1.2 mm. A light reflection layer, a recording layer, and a thin light transmission layer are sequentially formed, and a laser beam is incident from the thin light transmission layer side to record and reproduce signals on the recording layer. In this case, it is possible to configure an optical recording medium that can suppress coma aberration and satisfy mechanical characteristics by making the light transmission layer thin. However, in this method, the incident direction of the laser beam is different from the method of recording and reproducing the signal by making the laser beam incident from the transparent resin substrate side, which has been widely used.
[0014]
As a method for forming the light transmission layer described above, a light reflection layer, a recording layer, and the like are sequentially laminated on a transparent substrate, and then a resin sheet having a thickness of about 100 μm is pasted through an adhesive layer having a thickness of several μm. For example, a method of applying a thin film and a method of forming a thin light transmission layer by dropping an ultraviolet curable resin on the recording layer and spreading it and then curing it by irradiating with ultraviolet rays are known.
[0015]
[Problems to be solved by the invention]
However, in an optical recording medium having a structure in which a light reflecting layer, a recording layer (including a dielectric layer and a phase change recording layer), and a thin light transmission layer are sequentially formed on the transparent substrate described above, laser light is emitted from the thin light transmission layer side. When recording / reproduction is performed by irradiation, it is found that there is a problem that a large noise component is included in the reproduction signal when recording and reproducing signals significantly compared to the case of recording / reproduction from the conventional transparent substrate side. did. When the noise component is large, the reproduced signal is deteriorated, and the recorded signal cannot be reproduced stably, which causes a problem of improving the recording density. As a method for solving this problem, Japanese Patent Application Laid-Open No. 2000-306271 discloses a technique for smoothing at least one surface of a reflective layer and a dielectric layer. However, the technique described in this publication has a problem in that it cannot be said that a large noise component generated when recording / reproducing is performed by irradiating light from the light transmitting layer side.
[0016]
  Accordingly, an object of the present invention is to improve the noise component of an optical recording medium that records and reproduces light by irradiating light from the side of the thin light transmission layer.the body'sIt is to provide a manufacturing method.
[0017]
[Means for Solving the Problems]
  Optical recording medium of the present inventionIn this manufacturing method, at least one reflective film layer, one or more first dielectric layers, a recording layer, one or more second dielectric layers, and a light transmission layer are sequentially formed on a substrate. A method of manufacturing a medium, the step of forming the reflective film layer on a substrate, the step of performing sputter etching in the range of 5 nm to 20 nm on the surface of the reflective film layer following the step, A step of sequentially forming one or more first dielectric layers and the recording layer, a step of performing sputter etching on the surface of the recording layer on the surface of the recording layer subsequent to the step, And a step of sequentially forming one or more second dielectric layers and the light transmission layer in this order.
[0021]
Also, an optical recording medium in which at least one or more reflective film layers, one or more first dielectric layers, a recording layer, one or more second dielectric layers, and a light transmission layer are sequentially formed on a substrate. A method of forming the reflective film layer on a substrate; forming the one or more first dielectric layers; and etching the surface of the first dielectric layer following the steps. A step of performing sputter etching in the range of 0.5 to 6 nm, a step of sequentially forming the recording layer, and a sputter in the range of 0.1 to 4 nm on the surface of the recording layer following the step. It includes at least a step of performing etching, and a step of sequentially forming the one or more second dielectric layers and the light transmission layer in this order.
[0022]
Also, an optical recording medium in which at least one or more reflective film layers, one or more first dielectric layers, a recording layer, one or more second dielectric layers, and a light transmission layer are sequentially formed on a substrate. A method of depositing the reflective film layer on a substrate; a step of subsequently subjecting the reflective film layer surface to sputter etching with an etching amount ranging from 5 nm to 20 nm; A step of forming a first dielectric layer, a step of subjecting the surface of the first dielectric layer to sputter etching with an etching amount ranging from 0.5 nm to 6 nm, and a step of sequentially forming the recording layer. A step of forming a film, a step of subjecting the surface of the recording layer to sputter etching with an etching amount in the range of 0.1 nm to 4 nm, and a step of forming the one or more second dielectric layers and the light transmission layer. Sequentially formed in order Characterized in that it comprises at least a that step.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a cross-sectional configuration diagram of an optical recording medium showing a first embodiment of the present invention. As shown in FIG. 1, the optical recording medium of the present invention includes a substrate 1 / a reflective film layer 2 composed of one or more layers / a first dielectric layer 3 composed of one or more layers / a recording layer 4 / a second dielectric layer 5 / light. The transmission layer 7 has a configuration in which at least the layers are stacked in this order. Note that a protective layer, a base layer, or the like may be provided as appropriate between the layers. In this configuration, in the first embodiment, the surface of the reflective film layer 2 is a layer subjected to a sputter etching process of 5 nm to 20 nm, and the surface of the recording layer 4 is subjected to a sputter etching process of 0.1 to 4 nm. It is characterized by being a layer formed. In this way, by applying an appropriate amount of sputter etching to the surfaces of the reflective film layer 2 and the recording layer 4, noise is greatly improved when recording and reproducing the optical recording medium by laser irradiation from the light transmitting layer side. It is possible to realize a high-quality optical recording medium with low noise that is always in a constant state.
[0025]
FIG. 6 is a cross-sectional configuration diagram of an optical recording medium showing a second embodiment of the present invention. As shown in FIG. 2, the optical recording medium of this embodiment is similar to FIG. 1 described above. The optical recording medium of this embodiment is a substrate 1 / a reflective film layer 2 comprising one or more layers / a first dielectric layer 3 comprising one or more layers / a recording layer 4 / The second dielectric layer 5 / light transmission layer 7 is configured to be laminated at least in this order. In this case as well, a protective layer, a base layer, or the like may be provided as appropriate between the layers. In this embodiment, the surface of the first dielectric layer 3 is a layer subjected to a sputter etching process of 0.5 to 6 nm, and the surface of the recording layer 4 is subjected to a sputter etching process of 0.1 to 4 nm. It is characterized by being a layer. As described above, by applying an appropriate amount of sputter etching to the surfaces of the first dielectric layer 3 and the recording layer 4, noise can be remarkably suppressed as in the first embodiment.
[0026]
FIG. 11 is a cross-sectional configuration diagram of an optical recording medium showing a third embodiment of the present invention. As shown in FIG. 3, as in FIGS. 1 and 2, the optical recording medium of this embodiment includes a substrate 1 / a reflective film layer 2 composed of one or more layers / a first dielectric layer 3 composed of one or more layers / recording. The layer 4 / the second dielectric layer 5 / the light transmission layer 7 is configured to be laminated at least in this order. In this case as well, a protective layer, a base layer, or the like may be provided as appropriate between the layers. In this embodiment, the surface of the reflective film layer 2 is a layer subjected to a sputter etching process of 5 nm to 20 nm, and the surface of the first dielectric layer 3 is a layer subjected to a sputter etching process of 0.5 to 6 nm, The surface of the recording layer 4 is a layer that has been subjected to a sputter etching process of 0.1 to 4 nm. As described above, the surface of the reflective film layer 2, the first dielectric layer 3, and the recording layer 4 is subjected to an appropriate amount of sputter etching treatment, so that it is the same as or more than the first and second embodiments described above. Therefore, it is possible to realize an optical recording medium that can remarkably suppress noise and secure a certain low noise.
[0027]
【Example】
Example 1
In the first example, an example of the configuration of the optical recording medium according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing the configuration of an optical disk medium according to a first embodiment of the present invention. Here, a transparent resin substrate is used as the substrate 1, an AlTi (Ti: 2 wt%) alloy film is used as the reflective film layer 2, and the first As the dielectric layer 3 and the second dielectric layer 5, ZnS · SiO₂Film (SiO₂: 20 wt%), Ge as the phase change recording layer 4₂Sb₂Te_FiveAs the film and the light transmission layer 7, a PC film using an ultraviolet curable resin as an adhesive was used. Here, a description will be given of a case where the surface of the reflective layer 2 made of AlTi is subjected to an etching process and the surface of the recording layer 4 is also sputter-etched as a sputter etching for smoothing the recording film base surface.
[0028]
Details of the optical disk medium of this embodiment and its manufacturing process will be described below.
[0029]
Each layer is formed on the transparent resin substrate 1 on which a guide groove for guiding laser light is formed in advance using an in-line type sputtering apparatus according to the following procedure. First, the reflective film layer 2 made of an AlTi alloy film having a thickness of 120 nm uses an AlTi alloy target containing 2 wt% of Ti, the distance between the target and the substrate is 15 cm, and the power density is 1.6 (W / cm) in an argon gas atmosphere.²), A film is formed at a gas pressure of 0.08 (Pa). Next, the power density of 0.15 (W / cm) is applied to the surface of the reflective film layer 2 in an argon argon gas atmosphere.²), Sputter etching is performed under the condition of gas pressure 0.1 (Pa), and the surface of the AlTi film is subjected to etching processing of the sputter etching layer 8 (the part of the sputter etching layer 8 is not etched in the actual medium by the etching processing). Do. Next, ZnS-SiO₂The first dielectric layer 3 made of a film and having a thickness of 30 nm is made of ZnS · SiO₂(SiO₂: 20wt%) target, the target-substrate distance 15cm in argon gas atmosphere, power density 2.2 (W / cm²), And a film is formed at a gas pressure of 0.1 (Pa). Next, Ge₂Sb₂Te_FiveThe phase change recording layer 4 made of a film and having a thickness of 15 nm is made of Ge.₂Sb₂Te_FiveUsing a target, the distance between the target and the substrate is 15 cm and the power density is 0.27 (W / cm) in an argon gas atmosphere.²), A film is formed at a gas pressure of 1.0 (Pa). Next, the power density of 0.15 (W / cm) is applied to the surface of the phase change recording layer 4 in an argon argon gas atmosphere.²), Sputter etching under conditions of gas pressure 0.1 (Pa), about 2 nm Ge₂Sb₂Te_FiveThe sputter etching layer 9 is etched on the surface of the film. Next, ZnS · SiO₂The second dielectric layer 5 made of a film having a thickness of 130 nm is made of ZnS · SiO₂(SiO₂: 20wt%) target, the target-substrate distance 15cm in argon gas atmosphere, power density 2.2 (W / cm²), A film is formed under the condition of a gas pressure of 0.1 (Pa). In addition, the film formation time of each layer was adjusted appropriately so as to obtain a desired film thickness. After completion of the film formation, a 0.1 mm thick PC film 7 was adhered with an ultraviolet curable resin 6. The sectional configuration diagram of the medium according to the above embodiment is as shown in FIG. Although the sputter etching layer does not exist as a film, it is conceptually illustrated as a sputter etching layer 8 and a sputter etching layer 9 here.
[0030]
Here, in the present invention, the thickness of the sputter etching layer 9 on the surface of the phase change recording layer 4 is fixed to 2 nm, and the thickness of the sputter etching layer 8 on the surface of the reflective film layer 2 is changed in the range of 0 nm to 30 nm. The noise after initialization of the medium was measured.
[0031]
FIG. 2 shows the relationship between the noise after the initialization of the medium of this embodiment and the amount of sputter etching on the surface of the reflective film layer 2. It can be seen that when the etching amount on the surface of the reflective film layer is in the range of 0 nm to 5 nm, the noise rapidly decreases as the etching amount increases, and in the range of 5 nm or more, the noise gradually decreases as the etching amount decreases.
[0032]
FIG. 3 shows the relationship between the amount of noise increase after O / W (overwriting) and the amount of sputter etching on the surface of the reflective film layer 2 when the medium of this embodiment is used. It can be seen that the increase in noise after O / W is slight when the etching amount is in the range of 0 nm to 20 nm, but significantly increases when the etching amount exceeds 20 nm.
[0033]
Next, the medium configuration is the same as in the above embodiment, the thickness of the sputter etching layer 8 on the surface of the reflective film layer 2 is fixed to 15 nm, and the thickness of the sputter etching layer 9 on the surface of the phase change recording layer 4 is set to 0 nm to 5 nm. A medium changed in the above range was produced.
[0034]
FIG. 4 shows the measurement of the noise after the initialization of the medium. The relationship between the noise after the initialization and the sputter etching amount on the surface of the phase change recording layer 4 is shown. When the etching amount on the surface of the phase change recording layer is in the range of 0 nm to 0.1 nm, the noise rapidly decreases as the etching amount increases, and in the range of 0.1 nm or more, the noise gradually decreases as the etching amount decreases. I understand.
[0035]
FIG. 5 shows the relationship between the amount of noise increase after O / W (overwriting) (overwriting) and the amount of sputter etching on the surface of the phase change recording layer 4 when this medium is used. As can be seen from FIG. 5, the increase in noise after O / W is slight when the etching amount is in the range of 0 nm to 4 nm, but the O / W noise increases remarkably when the amount exceeds 4 nm or more.
[0036]
From the above, it can be seen that the sputter etching amount on the surface of the reflective film layer 2 is desirably in the range of 5 nm to 20 nm, and the sputter etching amount on the surface of the phase change recording layer 4 is desirably in the range of 0.1 nm to 4 nm. .
[0037]
(Example 2)
In the second example, an example of the configuration of the optical recording medium according to the second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view showing the configuration of an optical disk medium according to the second embodiment of the present invention. Here, a transparent resin substrate is used as the substrate 1, an AlTi (Ti: 2 wt%) alloy film is used as the reflective film layer 2, and the first As the dielectric layer 3 and the second dielectric layer 5, ZnS · SiO₂(SiO₂: 20 wt%) film, Ge as the phase change recording layer 4₂Sb₂Te_FiveAs the film and the light transmission layer 7, a PC film using an ultraviolet curable resin as an adhesive was used. And here, as a sputter etching for smoothing the recording film base surface, ZnS · SiO₂A case where the surface of the first dielectric layer 3 made of a film is etched and the surface of the phase change recording layer 4 is also etched will be described.
[0038]
Details of the phase change optical disk medium of this embodiment and the manufacturing process thereof will be described below.
[0039]
Each layer is formed on the transparent resin substrate 1 on which a guide groove for guiding laser light is formed in advance using an in-line type sputtering apparatus according to the following procedure.
[0040]
First, the reflective film layer 2 made of an AlTi alloy film having a thickness of 100 nm uses an AlTi alloy target containing 2 wt% of Ti, and the target-substrate distance is 15 cm and the power density is 1.6 (W / cm) in an argon gas atmosphere.²), A film is formed at a gas pressure of 0.08 (Pa). Next, ZnS-SiO₂The first dielectric layer 3 made of a film and having a thickness of 40 nm is made of ZnS · SiO₂(SiO₂: 20wt%) target, the target-substrate distance 15cm in argon gas atmosphere, power density 2.2 (W / cm²), And a film is formed at a gas pressure of 0.1 (Pa). Next, the first dielectric layer 3 (ZnS · SiO₂Film) Surface with argon and argon gas atmosphere, power density 0.15 (W / cm²), Sputter etching under conditions of gas pressure 0.1 (Pa), ZnS · SiO₂The sputter etching layer 10 is etched on the surface of the film. Next, Ge₂Sb₂Te_FiveThe phase change recording layer 4 made of a film and having a thickness of 15 nm is made of Ge.₂Sb₂Te_FiveUsing a target, the distance between the target and the substrate is 15 cm and the power density is 0.27 (W / cm) in an argon gas atmosphere.²), A film is formed at a gas pressure of 1.0 (Pa). Next, the power density of 0.15 (W / cm) is applied to the surface of the phase change recording layer 4 in an argon argon gas atmosphere.²), Sputter etching under conditions of gas pressure 0.1 (Pa), Ge₂Sb₂Te_FiveThe sputter etching layer 9 is etched on the surface of the film.
[0041]
Next, ZnS · SiO₂The second dielectric layer 5 made of a film having a thickness of 130 nm is made of ZnS · SiO₂(SiO₂: 20wt%) target, the target-substrate distance 15cm in argon gas atmosphere, power density 2.2 (W / cm²), A film is formed under the condition of a gas pressure of 0.1 (Pa). In addition, the film formation time of each layer was adjusted appropriately so as to obtain a desired film thickness. After completion of the film formation, a 0.1 mm thick PC film 7 was adhered with an ultraviolet curable resin 6. A cross-sectional view of the medium described above is shown in FIG. Although the sputter etching layer does not exist as a film originally, it is conceptually illustrated as a sputter etching layer 9 and a sputter etching layer 10 in FIG.
[0042]
Here, in the present invention, the thickness of the sputter etching layer 9 on the surface of the phase change recording layer 4 is fixed to 2 nm, and the first dielectric layer 3 (ZnS · SiO₂Film) A medium in which the thickness of the sputter etching layer 10 on the surface was changed in the range of 0 nm to 7 nm was prepared.
[0043]
FIG. 7 shows the result of measuring the noise after the medium initialization of this medium, and shows the relationship between the noise after the initialization and the sputter etching amount on the surface of the first dielectric layer 3. As can be seen from FIG. 7, when the etching amount on the surface of the first dielectric layer is in the range of 0 nm to 0.5 nm, noise rapidly decreases as the etching amount increases, and in the range of 0.5 nm or more, the etching amount gradually increases. It can be seen that the noise decreases with the decrease in.
[0044]
Next, FIG. 8 shows the result of investigating the relationship between the amount of noise increase after O / W (overwriting) and the amount of sputter etching on the surface of the first dielectric layer 3 for each of the media of this example manufactured as described above. Is shown. It can be seen that the increase in noise after O / W is slight when the etching amount is in the range of 0 nm to 6 nm, but the O / W noise increases remarkably when the etching amount exceeds 6 nm.
[0045]
Next, the medium configuration is the same as that of the above-described embodiment (configuration of FIG. 6), and the first dielectric layer 3 (ZnS · SiO₂Film) A medium was prepared in which the thickness of the sputter etching layer 10 on the surface was fixed to 3 nm and the thickness of the sputter etching layer 9 on the surface of the phase change recording layer 4 was changed in the range of 0 nm to 5 nm.
[0046]
FIG. 9 shows the noise after the medium initialization of this medium, and shows the relationship between the noise after the initialization and the sputter etching amount on the surface of the phase change recording layer 4 of each medium. When the etching amount on the surface of the phase change recording layer is in the range of 0 nm to 0.1 nm, the noise rapidly decreases as the etching amount increases, and in the range of 0.1 nm or more, the noise gradually decreases as the etching amount decreases. I understand.
[0047]
Further, FIG. 10 shows the relationship between the amount of noise increase after O / W (overwriting) of this medium and the amount of sputter etching on the surface of the phase change recording layer 4. As can be seen from FIG. 10, the increase in noise after O / W is slight when the etching amount is in the range of 0 nm to 4 nm, but the O / W noise increases remarkably when the amount exceeds 4 nm.
[0048]
From the above, the sputter etching amount on the surface of the first dielectric layer 3 is desirably in the range of 0.5 nm to 6 nm, and the sputter etching amount on the surface of the phase change recording layer 4 is desirably in the range of 0.1 nm to 4 nm. I understand that.
[0049]
(Example 3)
In the third example, an example of the configuration of the optical recording medium according to the third embodiment of the present invention will be described with reference to FIG. FIG. 11 is a cross-sectional view showing the medium configuration of the third embodiment of the present invention. Here, a transparent resin substrate is used as the substrate 1, an AlTi (Ti: 2 wt%) alloy film is used as the reflective film layer 2, and the first dielectric is shown. ZnS · SiO as the body layer 3 and the second dielectric layer 5₂Ge as the film, phase change recording layer 4₂Sb₂Te_FiveA film, a PC film using an ultraviolet curable resin as an adhesive is used as the light transmission layer 7, and the surface of the AlTi reflective layer 2 and ZnS · SiO are used as sputter etching for improving medium characteristics.₂The case where the etching process is performed on the surface of the first dielectric layer 3 and the surface of the phase change recording layer 4 are described.
[0050]
The phase change optical disk medium of this embodiment and the manufacturing process thereof will be described in detail below.
[0051]
Each layer is formed on the transparent resin substrate 1 on which guide grooves for guiding the laser beam are formed in advance by the following procedure using an in-line type sputtering apparatus.
[0052]
First, the reflective film layer 2 made of an AlTi alloy film having a thickness of 120 nm uses an AlTi alloy target containing 2 wt% of Ti, the distance between the target and the substrate is 15 cm, and the power density is 1.6 (W / cm) in an argon gas atmosphere.²), A film is formed at a gas pressure of 0.08 (Pa). Next, the power density of 0.15 (W / cm) is applied to the surface of the reflective film layer 2 in an argon argon gas atmosphere.²), The etching process of the sputter etching layer 8 of about 10 nm is performed under the condition of the gas pressure of 0.1 (Pa). Next, ZnS-SiO₂The first dielectric layer 3 made of a film and having a thickness of 30 nm is made of ZnS · SiO₂(SiO₂: 20wt%) target, the target-substrate distance 15cm in argon gas atmosphere, power density 2.2 (W / cm²), And a film is formed at a gas pressure of 0.1 (Pa). Next, ZnS-SiO₂A power density of 0.15 (W / cm) is formed on the surface of the first dielectric layer 3 made of a film having a thickness of 30 nm in an argon argon gas atmosphere.²), An etching process of the sputter etching layer 10 of about 3 nm is performed under the condition of a gas pressure of 0.1 (Pa). Next, Ge₂Sb₂Te_FiveThe phase change recording layer 4 made of a film and having a thickness of 15 nm is made of Ge.₂Sb₂Te_FiveUsing a target, the distance between the target and the substrate is 15 cm and the power density is 0.27 (W / cm) in an argon gas atmosphere.²), A film is formed at a gas pressure of 1.0 (Pa). Next, the power density of 0.15 (W / cm) is applied to the surface of the phase change recording layer 4 in an argon gas atmosphere.²), Sputter etching under conditions of gas pressure 0.1 (Pa), Ge₂Sb₂Te_FiveThe sputter etching layer 9 on the film surface is etched. Next, ZnS · SiO₂The second dielectric layer 5 made of a film having a thickness of 130 nm is made of ZnS · SiO₂(SiO₂: 20wt%) target, the target-substrate distance 15cm in argon gas atmosphere, power density 2.2 (W / cm²), A film is formed under the condition of a gas pressure of 0.1 (Pa). In addition, the film formation time of each layer was adjusted appropriately so as to obtain a desired film thickness. After completion of the film formation, a 0.1 mm thick PC film 7 was adhered with an ultraviolet curable resin 6. A cross-sectional view of the above-described medium is as shown in FIG. Note that the sputter etching layer is originally a portion that does not exist as a film, but is conceptually illustrated as a sputter etching layer 8, a sputter etching layer 9, and a sputter etching layer 10 here.
[0053]
Here, in this embodiment, the thickness of the sputter etching layer 8 on the surface of the reflective film layer 2 is fixed to 10 nm, and the thickness of the sputter etching layer 10 on the surface of the first dielectric layer 3 is fixed to 3 nm. A medium in which the thickness of the sputter-etched layer 9 on the surface of the layer 4 was changed in the range of 0 nm to 5 nm was produced.
[0054]
FIG. 12 shows the measurement of noise after initialization of the medium. The relationship between the noise after initialization and the sputter etching amount on the surface of the phase change recording layer is shown. As can be seen from FIG. 12, when the etching amount on the surface of the phase change recording layer is in the range of 0 nm to 0.1 nm, the noise rapidly decreases as the etching amount increases, and in the range of 0.1 nm or more, the etching amount gradually increases. It can be seen that noise decreases with the decrease.
[0055]
FIG. 13 shows the relationship between the amount of noise increase after O / W (overwriting) and the amount of sputter etching on the surface of the phase change recording layer 4 of each medium of this example. From FIG. 13, it can be seen that when the etching amount is in the range of 0 nm to 4 nm, the noise rise after O / W is slight, but when it exceeds 4 nm, the O / W noise is remarkably increased.
[0056]
From the above, it can be seen that the sputter etching amount on the surface of the recording layer is preferably in the range of 0.1 nm to 4 nm.
[0057]
In the present invention, the material, composition, and the like of the recording layer, the reflective layer, and the dielectric layer are not limited to those in the above-described embodiments. The reflective layer may be an AlCu film, AlCr film, NiCr film, NiCu film, AgPdCu film, etc., and the dielectric layer may be a SiN film, SiO₂A film, a TaO film, or the like may be used. Even when these films are used, the same effect as in the above-described embodiment can be achieved. In addition, the reflective layer, the first dielectric layer, and the second dielectric layer that constitute the optical recording medium may have a laminated structure instead of the one-layer configuration shown in the above-described examples and embodiments. In particular, in this case, the effect of etching the surface of the reflective layer and the first dielectric layer in the examples and embodiments described above is that the surface of at least one of the reflective layers of the multilayer structure, the first dielectric layer of the multilayer structure If an etching process is performed on at least one of the surfaces, the same effect as in the above embodiment can be obtained. Further, the film forming method, film forming conditions, etching conditions, etc. of each film are not limited to those of the above-described embodiments, and any film quality may be obtained as long as a desired film quality is obtained. The material and thickness of the substrate are not limited to the above-described resin material and thickness, and may be appropriately selected as necessary. Further, in the above embodiment, a PC film having a thickness of 100 μm was used for the light transmission layer. Instead, any film that transmits light, such as a UV-cured resin applied and cured, may be used. It is not limited.
[0058]
In the above-described embodiments, an example in which an in-line type film forming apparatus is used as a thin film forming apparatus constituting the medium has been described. However, it is obvious that a single-layer film forming apparatus that processes substrates one by one may be used. It is. Further, in this embodiment, the type of optical recording medium is described as a phase change type disk, but the present invention is not limited to this, and can be similarly applied to other optical recording media such as a magneto-optical disk. .
[0059]
【The invention's effect】
  As described above, according to the present invention, when each thin film is formed on the substrate, an appropriate amount of sputter etching is applied to the surface of the reflective film layer or the surface of the first dielectric layer and the surface of the recording layer. Noise and high quality optical recording mediathe body'sA manufacturing method can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of an optical recording medium showing a first embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between the sputter etching amount on the surface of the reflective film layer and the noise after initialization in the optical recording medium of the first embodiment of the present invention.
FIG. 3 is a diagram showing the relationship between the amount of sputter etching on the surface of the reflective film layer and the increase in noise after O / W in the optical recording medium of the first embodiment of the present invention.
FIG. 4 is a diagram showing the relationship between the sputter etching amount on the surface of the phase change recording layer and the noise after initialization in the optical recording medium of the first embodiment of the present invention.
FIG. 5 is a diagram showing the relationship between the amount of sputter etching on the surface of the phase change recording layer and the noise increase after O / W in the optical recording medium of the first embodiment of the present invention.
FIG. 6 is a cross-sectional configuration diagram of an optical recording medium showing a second embodiment of the present invention.
FIG. 7 is a graph showing the relationship between the sputter etching amount on the surface of the first dielectric layer and the noise after initialization in the optical recording medium of the second embodiment of the present invention.
FIG. 8 is a diagram showing a sputter etching amount on the surface of the first dielectric layer and an increase in noise after O / W in the optical recording medium of the second embodiment of the present invention.
FIG. 9 is a diagram showing the relationship between the sputter etching amount on the surface of the recording layer and the noise after initialization in the optical recording medium of the second embodiment of the present invention.
FIG. 10 is a graph showing the relationship between the sputter etching amount on the surface of the recording layer and the noise increase after O / W in the optical recording medium of the second embodiment of the present invention.
FIG. 11 is a cross-sectional configuration diagram of an optical recording medium showing a third embodiment of the present invention.
FIG. 12 is a diagram showing the relationship between the sputter etching amount on the surface of the phase change recording film and the noise after initialization in the optical recording medium of the third embodiment of the present invention.
FIG. 13 is a diagram showing the relationship between the amount of sputter etching on the phase change recording film surface and the noise increase after O / W in the optical recording medium of the third embodiment of the present invention.
[Explanation of symbols]
1 ... Board
2 ... Reflective film layer
3. First dielectric layer
4. Recording layer
5 ... Second dielectric layer
6 ... UV curable resin layer
7. Light transmission layer
8 ... Sputter etching layer on the surface of the reflective film layer
9: Sputter etching layer on the surface of the recording layer
10 ... Sputter etching layer on the surface of the first dielectric layer

Claims (3)

  A method for producing an optical recording medium, wherein at least one reflective film layer, one or more first dielectric layers, a recording layer, one or more second dielectric layers, and a light transmission layer are sequentially formed on a substrate. A step of forming the reflective film layer on the substrate, a step of performing sputter etching in the range of 5 nm to 20 nm on the surface of the reflective film layer subsequent to the step, and the first or more first layers. Sequentially forming the dielectric layer and the recording layer, subjecting the surface of the recording layer to sputter etching with an etching amount in the range of 0.1 nm to 4 nm, and the second or more second layers. And a step of sequentially forming the light transmission layer in this order.   A method for producing an optical recording medium, wherein at least one reflective film layer, one or more first dielectric layers, a recording layer, one or more second dielectric layers, and a light transmission layer are sequentially formed on a substrate. And a step of forming the reflective film layer on the substrate, a step of forming the one or more first dielectric layers, and an etching amount on the surface of the first dielectric layer following the steps. A step of performing sputter etching in the range of 0.5 nm to 6 nm, a step of sequentially forming the recording layer, and a sputter etching in the range of etching amount of 0.1 nm to 4 nm on the surface of the recording layer following the step. A method of manufacturing an optical recording medium including at least a step of applying and a step of sequentially forming the one or more second dielectric layers and the light transmission layer in this order.   A method for producing an optical recording medium, wherein at least one reflective film layer, one or more first dielectric layers, a recording layer, one or more second dielectric layers, and a light transmission layer are sequentially formed on a substrate. A step of forming the reflective film layer on the substrate, a step of performing sputter etching in the range of 5 nm to 20 nm on the surface of the reflective film layer subsequent to the step, and the first or more first layers. Next, a step of forming a dielectric layer, a step of subjecting the surface of the first dielectric layer to sputter etching with an etching amount ranging from 0.5 nm to 6 nm, and a step of depositing the recording layer are sequentially formed. A step of performing sputter etching on the surface of the optical recording layer in the range of 0.1 nm to 4 nm subsequent to the step, the second dielectric layer of one or more layers, and the light transmission layer in this order. Sequentially Method for producing at least comprises an optical recording medium and a degree.

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