JP2007141420A - Write-once type optical recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the total number of films of an inorganic recording film and to enhance recording sensitivity in a write-once type recording medium having the inorganic recording film. <P>SOLUTION: The write-once type optical recording medium 10 has the inorganic recording film 6 and the inorganic recording film 6 is provided with an oxide film 3 made of an oxide of germanium and a metallic film 2 adjacent to the oxide film. The metallic film 2 is provided with a first metallic film 2a comprising titanium and silicon and a second metallic film 2b comprising titanium and silicon and having a composition different from that of the first metallic film 2a and the second metallic film 2b of the metallic films is provided so as to be positioned on the oxide film 3 side. When the compositions of the first and the second metallic films 2a and 2b are defined as TiSi<SB>x</SB>and TiSi<SB>y</SB>, respectively, TiSi<SB>x</SB>and TiSi<SB>y</SB>satisfy a relation of x<y. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a write-once optical recording medium and a method for manufacturing the same. Specifically, the present invention relates to a write-once optical recording medium having an inorganic recording film and a manufacturing method thereof.

  In recent years, optical recording media capable of recording information signals at high density have been desired. For example, in order to meet this requirement, a Blu-ray Disc (registered trademark) (hereinafter referred to as BD) standard has been established, and high-definition images can be recorded and stored on an optical recording medium.

  High recording density optical recording media represented by this BD include standards for read-only optical recording media, rewritable optical recording media, and write-once optical recording media. It is desired to be inexpensive.

  Conventionally, organic dyes have been used as recording films for write-once optical recording media, as is widely known, for example, in CD-R (Compact Disc-Recordable) and DVD-R (Digital Versatile Disc-Recordable). . However, in a write-once type optical recording medium for high-density recording, it is difficult to form a recording film from an organic material, and therefore it has been proposed to form a recording film using an inorganic material (see, for example, Patent Document 1). ).

JP-A-11-144316

  However, when forming a recording film using an inorganic material, it is necessary to increase the total number of films in order to improve recording characteristics and durability. When the total number of films increases in this way, productivity decreases and the manufacturing apparatus becomes complicated. Furthermore, not only the material cost of the write-once optical recording medium is increased, but also a large amount of capital investment is required for a manufacturing apparatus for forming a recording film, for example, a sputtering apparatus. It also becomes difficult to provide.

  Therefore, it is desired to reduce the total number of recording films and reduce the total film thickness. Furthermore, in recent years, high linear velocity recording and multilayer recording films are also desired. To meet this requirement, it is necessary to improve recording sensitivity.

  Accordingly, an object of the present invention is a write-once optical recording medium having an inorganic recording film, the write-once optical recording medium capable of reducing the total number of inorganic recording films and improving recording sensitivity, and the recording medium It is to provide a manufacturing method.

In order to solve the above-mentioned problem, the first invention is a write-once optical recording medium having an inorganic recording film,
Inorganic recording film
An oxide film made of germanium oxide;
An adjacent film adjacent to the oxide film,
Adjacent membrane
A first adjacent film made of titanium and silicon;
A second adjacent film made of titanium and silicon having a composition different from that of the first adjacent film,
Of the first and second adjacent films, the second adjacent film is provided on the oxide film side,
When the compositions of the first and second adjacent films are expressed as TiSi _x and TiSi _y , respectively, the write-once type optical recording medium is characterized in that TiSi _x and TiSi _y satisfy the relationship x <y.

A second invention is a method of manufacturing a write once optical recording medium having an inorganic recording film,
Forming an oxide film made of a germanium oxide;
Forming an adjacent film made of metal, and
The adjacent film formation process is:
Forming a first adjacent film made of titanium and silicon;
Forming a second adjacent film made of titanium and silicon having a composition different from that of the first adjacent film,
In the step of forming the oxide film and the adjacent film, the oxide film and the second adjacent film are formed adjacent to each other,
The first and second composition adjacent film respectively TiSi _x, when expressed as TiSi _y, is TiSi _x, a manufacturing method of a write-once optical recording medium TiSi _y is characterized by satisfying the relation of x <y .

  In the first and second inventions, since the inorganic recording film is composed of an oxide film made of germanium oxide and an adjacent film adjacent to the oxide film, when the inorganic recording film is irradiated with light, the adjacent film Due to the photocatalytic effect, the oxide film is separated so as to increase oxygen on the adjacent film side. Accordingly, the oxide film is separated into a layer having a high oxygen concentration and a layer having a low oxygen concentration, and the optical constant of the oxide film is greatly changed. Therefore, a reproduction signal having a large modulation degree can be obtained, and thus good recording characteristics can be realized.

  In the first and second inventions, the adjacent film is made of titanium and silicon having a composition different from that of the first adjacent film made of titanium and silicon, and the silicon of the second adjacent film. Is higher than that of the first adjacent film, so that the recording sensitivity of the inorganic recording film can be improved.

A third invention is a write once optical recording medium having an inorganic recording film,
Inorganic recording film
An oxide film made of germanium oxide;
An adjacent film adjacent to the oxide film,
Adjacent membrane
A first adjacent film made of aluminum;
A second adjacent film made of titanium,
The write-once type optical recording medium is characterized in that the second adjacent film of the first and second adjacent films is provided on the oxide film side.

A fourth invention is a method of manufacturing a write once optical recording medium having an inorganic recording film,
Forming an oxide film made of a germanium oxide;
Forming an adjacent film made of metal, and
The adjacent film formation process is:
Forming a first adjacent film made of aluminum;
Forming a second adjacent film made of titanium,
In the step of forming the oxide film and the adjacent film, the oxide film and the second adjacent film are formed adjacent to each other,
In the film forming step of the oxide film and the adjacent film, the write-once type optical recording medium manufacturing method is characterized in that the oxide film and the adjacent film are formed adjacent to each other.

  In the third and fourth inventions, since the inorganic recording film is composed of an oxide film made of germanium oxide and an adjacent film adjacent to the oxide film, when the inorganic recording film is irradiated with light, the adjacent film Due to the photocatalytic effect, the oxide film is separated so as to increase oxygen on the adjacent film side. Accordingly, the oxide film is separated into a layer having a high oxygen concentration and a layer having a low oxygen concentration, and the optical constant of the oxide film is greatly changed. Therefore, a reproduction signal having a large modulation degree can be obtained, and thus good recording characteristics can be realized.

  In the third and fourth inventions, the adjacent film includes a first adjacent film made of titanium and silicon, and a second adjacent film made of titanium and silicon having a composition different from that of the first adjacent film. Since the second adjacent film is provided on the oxide film side among the first and second adjacent films, the recording sensitivity of the inorganic recording film can be improved.

  In the second and fourth inventions, it is preferable to continuously perform the film forming steps of the oxide film and the adjacent film. By forming the film in this way, it is possible to prevent an oxide film from being formed between the oxide film and the adjacent film or impurities from being attached.

  In the third and fourth inventions, it is preferable that the first adjacent film further contains Si. Moreover, it is preferable that the film thickness of a 1st adjacent film | membrane is 7 mm or less.

  In the first and third inventions, it is preferable to provide an identification information recording area in which identification information is recorded. This identification information is preferably recorded by forming a recording mark corresponding to the identification information on the oxide film, or is recorded by removing the inorganic recording film with a pattern corresponding to the identification information.

  In the second and fourth inventions, it is preferable to further include a step of recording the identification information by irradiating the write-once optical recording medium with laser light having a wavelength of 350 nm or more and 450 nm or less from the oxide film side. Further, it is preferable to further include a step of recording identification information by irradiating the write-once type optical recording medium from the adjacent film side, and the laser beam irradiated in this step is an optical head scan speed. The write-once type optical recording medium is preferably irradiated under conditions of 5 m / s to 9 m / s and laser power of 3400 mW to 4000 mW.

  As described above, according to the present invention, in the write-once type optical recording medium having an inorganic recording film, the total number of inorganic recording films can be reduced and the recording sensitivity can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.

(1) First embodiment
Configuration of Write-once Type Optical Recording Medium FIG. 1 is a schematic sectional view showing an example of the configuration of a write-once type optical recording medium according to the first embodiment of the present invention. This recordable optical recording medium 10 has a structure in which an inorganic recording film 6, a dielectric film 4, and a light transmission layer 5 are sequentially laminated on a substrate 1.

In the write-once type optical recording medium 10 according to the first embodiment, information signals are recorded or reproduced by irradiating the inorganic recording film 6 with laser light from the light transmission layer 5 side. For example, laser light having a wavelength in the range of 400 nm or more and 410 nm or less is condensed by an objective lens having a numerical aperture in the range of 0.84 or more and 0.86 or less, and is applied to the inorganic recording film 6 from the light transmission layer 5 side. The information signal is recorded or reproduced by irradiation. An example of such a write-once optical recording medium 10 is a BD-R (Blu-ray Disc-Recordable).
Hereinafter, the substrate 1, the inorganic recording film 6, the dielectric film 4, and the light transmission layer 5 constituting the write-once type optical recording medium 10 will be sequentially described.

(substrate)
The substrate 1 has an annular shape with an opening (hereinafter referred to as a center hole) formed in the center. One main surface of the substrate 1 is an uneven surface 11, and the inorganic recording film 6 is formed on the uneven surface 11. In the following, the concave portion recessed with respect to one main surface of the substrate 1 is referred to as an in-groove 11G, and the convex portion protruding with respect to one main surface of the substrate 1 is referred to as an on-groove 11L.

  Examples of the shapes of the in-groove 11G and the on-groove 11L include various shapes such as a spiral shape and a concentric circle shape. Further, the in-groove 11G and / or the on-groove 11L are wobbled (meandering) for adding address information.

  The diameter of the substrate 1 is selected to be 120 mm, for example. The thickness of the substrate 1 is selected in consideration of rigidity, preferably from 0.3 mm to 1.3 mm, more preferably from 0.6 mm to 1.3 mm, for example, 1.1 mm. It is. The diameter (radius) of the center hole is selected to be 15 mm, for example.

  As the material of the substrate 1, for example, a plastic material such as polycarbonate resin, polyolefin resin, or acrylic resin, or glass can be used. In consideration of cost, it is preferable to use a plastic material as the material of the substrate 1.

(Inorganic recording film)
The inorganic recording film 6 includes a metal film 2 and an oxide film 3 that are sequentially stacked on the uneven surface 11 of the substrate 1. The metal film 2 includes a first metal film 2 a and a second metal film 2 b, and is provided so that the second metal film 2 b is in contact with the oxide film 3.

The first metal film 2a and the second metal film 2b are made of TiSi. When the compositions of the first metal film 2a and the second metal film 2b are expressed as TiSi _x and TiSi _y , respectively, it is preferable that TiSi _x and TiSi _y satisfy the relationship x <y.

  The first metal film 2a and the second metal film 2b may further contain an additive. Examples of the additive include Al, Ag, Cu, Pd, Ge, Si, Sn, and Ni. , Fe, Mg, V, C, Ca, B, Cr, Nb, Zr, S, Se, Mn, Ga, Mo, W, Tb, Dy, Gd, Nd, Zn, Ta, Sr One or more types can be used. By including such an additive, for example, optical characteristics, durability, recording sensitivity, and the like can be improved.

  The oxide film 3 is made of an oxide of Ge, for example. The absorption coefficient k of the oxide film 3 is preferably in the range of 0.15 to 0.90, more preferably 0.20 to 0.70, and still more preferably 0.25 to 0.60. By satisfying the range of 0.15 or more and 0.90 or less, for example, a good modulation degree and a carrier-to-noise ratio (hereinafter, C / N ratio) can be obtained. By satisfying the range of 0.20 or more and 0.70 or less, for example, a better modulation degree and C / N ratio can be obtained. By satisfying the range of 0.25 or more and 0.60 or less, for example, an even better modulation degree and C / N ratio can be obtained.

  The absorption coefficient in this specification is at a wavelength of 410 nm. For the measurement, an ellipsometer (manufactured by Rudolf, trade name: Auto EL-462P17) was used.

  The thickness of the oxide film 3 is preferably in the range of 10 nm to 35 nm. Further, an additive may be added to the oxide film 3. Examples of the additive include Te, Pd, Pt, Cu, Zn, Au, Ag, Si, Ti, Fe, Ni, Sn, Sb or the like can be used. By adding such an additive, durability and / or reactivity (recording sensitivity) can be improved. In order to improve durability, Pd, Pt, Si, and Sb are particularly preferable.

(Dielectric film)
The first dielectric film 4 a and the second dielectric film 4 b are laminated on the inorganic recording film 6 to improve the optical and mechanical protection of the inorganic recording film 6, that is, to improve durability, and to perform inorganic recording. This is for performing deformation of the recording film 6, that is, suppression of swelling.

The first dielectric film 4a is made of, for example, ZnS—SiO ₂ . The thickness of the first dielectric film 4a is preferably in the range of 10 nm to 58 nm, more preferably in the range of 23 nm to 53 nm. By setting the film thickness to 10 nm or more, good jitter can be obtained. For example, when the write-once optical recording medium 10 is a BD-R, a jitter of 6.5% or less, which is a BD-R standard, can be satisfied by setting the film thickness to 10 nm or more. On the other hand, a favorable reflectance can be obtained by making a film thickness into 58 nm or less. For example, when the write-once optical recording medium 10 is a BD-R, the reflectance of 12% or less required by the BD-R standard can be satisfied by setting the film thickness to 58 nm or less.
Further, when the film thickness is 23 nm or more, better jitter can be obtained. On the other hand, when the film thickness is 53 nm or less, a better reflectance can be obtained.

  The second dielectric film 4b is made of, for example, SiN. The thickness of the second dielectric film 4b is preferably selected from the range of 35 nm or less. By setting the film thickness to 35 nm or less, good jitter can be obtained. For example, when the write-once optical recording medium 10 is a BD-R, a jitter of 6.5% or less, which is a BD-R standard, can be satisfied by setting the film thickness to 35 nm or less. Further, as described above, by laminating the first dielectric layer 4a and the second dielectric layer 4b, the degree of modulation can be increased and the carrier-to-noise ratio (hereinafter referred to as C / N ratio) can be increased. Can be high.

(Light transmission layer)
The light transmissive layer 5 includes, for example, a light transmissive sheet (film) having an annular shape and an adhesive layer for bonding the light transmissive sheet to the substrate 1. The adhesive layer is made of, for example, an ultraviolet curable resin or a pressure sensitive adhesive (PSA). The thickness of the light transmission layer 5 is preferably selected from the range of 10 μm or more and 177 μm or less, for example, 100 μm. By combining such a thin light transmission layer 5 with an objective lens having a high NA (numerical aperture) of, for example, about 0.85, high-density recording can be realized.

  The light-transmitting sheet is preferably made of a material having a low absorption ability with respect to laser light used for recording and / or reproduction, specifically, a material having a transmittance of 90% or more. Examples of the material for the light transmissive sheet include polycarbonate resin materials and polyolefin resins (for example, ZEONEX (registered trademark)).

  Further, the thickness of the light transmissive sheet is preferably selected to be 0.3 mm or less, more preferably from 3 to 177 μm. The inner diameter (diameter) of the light transmission layer 5 is selected to be 22.7 mm, for example.

Method for Manufacturing Write-Once Optical Recording Medium Next, a method for manufacturing a write-once optical recording medium according to an embodiment of the present invention will be described.
(Substrate molding process)
First, the board | substrate 1 in which the uneven surface 11 was formed in one main surface is shape | molded. As a method for molding the substrate 1, for example, an injection molding (injection) method, a photopolymer method (2P method: Photo Polymerization), or the like can be used.

(First metal film forming step)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target made of, for example, TiSi, and evacuated in the vacuum chamber until a predetermined pressure is reached. Thereafter, a target is sputtered while introducing a process gas into the vacuum chamber, and a first metal film 2 a is formed on the substrate 1.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1-0.6Pa
Input power: 1-3kW
Gas type: Ar gas Gas flow rate: 10-40 sccm

(Second metal film deposition step)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target made of, for example, TiSi, and evacuated in the vacuum chamber until a predetermined pressure is reached. Thereafter, the target is sputtered while introducing the process gas into the vacuum chamber, and the second metal film 2b is formed on the substrate 1. In the film forming process of the second metal film 2b, a target having a composition different from that of the target used in the film forming process of the first metal film 2a is used. Moreover, the target used in the film forming process of the second metal film 2b has a higher Si content than that used in the film forming process of the first metal film 2a. For example, when the composition of the target for forming the first metal film 2a and the second metal film 2b is expressed as TiSix and TiSiy, respectively, TiSix and TiSiy satisfy the relationship x <y.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1-0.6Pa
Input power: 1-3kW
Gas type: Ar gas Gas flow rate: 10-40 sccm

(Oxide film deposition process)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target made of, for example, Ge oxide, and is evacuated to a predetermined pressure in the vacuum chamber. Thereafter, the target is sputtered while introducing the process gas into the vacuum chamber, and the oxide film 3 is formed on the second metal film 2b.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1-0.6Pa
Input power: 1-3kW
Gas type: Ar gas Ar gas flow rate: 10-80 sccm

(First dielectric film forming step)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target made of, for example, ZnS—SiO ₂ , and evacuated to a predetermined pressure in the vacuum chamber. Thereafter, the target is sputtered while introducing the process gas into the vacuum chamber, and the first dielectric film 4 a is formed on the oxide film 3.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1-0.6Pa
Input power: 1-5kW
Gas type: Ar gas Ar gas flow rate: 6 sccm

(Second dielectric film forming step)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target made of, for example, Si, and evacuated to a predetermined pressure in the vacuum chamber. Thereafter, the target is sputtered while introducing the process gas into the vacuum chamber, and the second dielectric film 4b is formed on the first dielectric film 4a.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1-0.6Pa
Input power: 1-4kW
Gas type: Ar gas and nitrogen gas Ar gas flow rate: 50 sccm
Nitrogen gas flow rate: 37sccm

(Light transmission layer forming process)
Next, an annular light-transmitting sheet is bonded to the uneven surface 11 side on the substrate 1 using, for example, a pressure-sensitive adhesive (PSA) uniformly applied in advance to one main surface of the sheet. Thereby, the light transmission layer 5 is formed so as to cover the laminated film laminated on the substrate 1.
The write-once type optical recording medium 10 shown in FIG. 1 is obtained by the above process.

Configuration of Target The configuration of the target for forming the oxide film 3 will be described below. A target for forming the oxide film 3 is obtained by pressurizing and firing a mixture of Ge powder as a semiconductor powder and Ge oxide powder as a semiconductor oxide powder. This target has a disk shape, for example, and its diameter is selected to be 200 mm, for example, and its thickness is selected to be 6 mm, for example.

  The oxygen content after pressure firing is preferably in the range of 45 atomic% to 60 atomic%. If it is less than 45 atomic%, the absorption coefficient k exceeds 0.9, so that the recording characteristics and the like deteriorate. On the other hand, if it exceeds 60 atomic%, the absorption coefficient becomes less than 0.15, so that the recording characteristics and the like deteriorate.

  Here, the metal unsaturated oxide is a compound shifted in a direction in which the oxygen content is less than the stoichiometric composition corresponding to the maximum valence that the metal can take, that is, the oxygen in the metal unsaturated oxide. It is a compound whose content is smaller than the oxygen content of the stoichiometric composition corresponding to the maximum valence that the metal can take.

  As the unsaturated oxide or unsaturated nitride, in addition to one kind of unsaturated oxide or unsaturated nitride, the addition of a second element or a plurality of other elements is also included in the present invention. I will decide.

Target Manufacturing Method A target manufacturing method for forming the oxide film 3 will be described below.
(Weighing and mixing)
A predetermined amount of each of the Ge powder as the semiconductor powder and the Ge oxide powder as the semiconductor oxide powder is weighed, and then, for example, a mixed dry method is performed. Here, the mixing ratio of the Ge powder and the Ge oxide powder is preferably adjusted so that the oxygen content after pressure firing is not less than 45 atomic% and not more than 60 atomic%.

(Pressurized firing)
Next, the mixed powder obtained as described above is put into a carbon mold and subjected to pressure firing, for example, with a hot press apparatus to obtain a fired body. Here, a hot press apparatus may be generally used, and by using this apparatus, firing is performed for a predetermined time in a non-oxygen atmosphere at a constant pressure and a constant firing temperature.

(Finishing process)
The fired body obtained as described above is machined so as to have a disk shape of a predetermined size. As described above, the target can be obtained.

  In the first embodiment of the present invention, the first metal film 2a, the second metal film 2b, the oxide film 3, the first dielectric film 4a, the second dielectric film 2b, and the light transmission layer 5 are formed. Since the write-once optical recording medium 10 can be manufactured simply by sequentially laminating on the substrate 1, the high-recording density write-once optical recording medium 10 having a simple film configuration can be provided. That is, the inexpensive write-once type optical recording medium 10 with high recording density can be provided.

  Further, since the oxide film 3 is formed by sputtering a target made of Ge oxide, the oxide film 3 having a constant oxygen concentration, that is, a constant absorption coefficient can be formed during mass production.

  The metal film 2 is composed of a first metal film 2a made of TiSi and a second metal film 2b made of TiSi having a composition different from that of the first metal film 2b. Since the Si content is less than the Si content of the second metal film, the recording sensitivity can be improved. This ensures a wide margin on the high power side and widens the OPC (Optimum Power Control, drive recording area optimization) range. Furthermore, it becomes easy to cope with high linear velocity recording and high capacity multilayer media having two or more layers.

(2) Second embodiment
Configuration of Write-once Type Optical Recording Medium This write-once type optical recording medium 10 has a configuration in which an inorganic recording film 6, a dielectric film 4, and a light transmission layer 5 are sequentially laminated on a substrate 1. The inorganic recording film 6 is configured by sequentially laminating a metal film 2 and an oxide film 3 on the substrate 2. Since the components other than the metal film 2 are the same as those in the first embodiment, only the inorganic recording film 6 will be described below.

  The metal film 2 is composed of a first metal film 2a made of Al and a second metal film 2b made of TiSi, and is provided so that the second metal film 2b is adjacent to the oxide film. The film thickness of the first metal film 2a is preferably 7 nm or less. The first metal film 2a and the second metal film 2b may further contain an additive. For example, the same additive as in the first embodiment described above may be used. Can do.

Method for Manufacturing Write-Once Optical Recording Medium Next, a method for manufacturing a write-once optical recording medium according to an embodiment of the present invention will be described.
(Substrate molding process)
First, the board | substrate 1 in which the uneven surface 11 was formed in one main surface is shape | molded. As a method for molding the substrate 1, for example, an injection molding (injection) method, a photopolymer method (2P method: Photo Polymerization), or the like can be used.

(First metal film forming step)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target made of, for example, Al, and is evacuated until a predetermined pressure is reached in the vacuum chamber. Thereafter, a target is sputtered while introducing a process gas into the vacuum chamber, and a first metal film 2 a is formed on the substrate 1.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1-0.6Pa
Input power: 1-3kW
Gas type: Ar gas Gas flow rate: 10-40 sccm

(Second metal film deposition step)
Next, the substrate 1 is transferred into a vacuum chamber provided with a target made of, for example, TiSi, and evacuated in the vacuum chamber until a predetermined pressure is reached. Thereafter, the target is sputtered while introducing the process gas into the vacuum chamber, and the second metal film 2b is formed on the substrate 1.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1-0.6Pa
Input power: 1-3kW
Gas type: Ar gas Gas flow rate: 10-40 sccm
The subsequent steps are the same as those in the first embodiment described above, and a description thereof will be omitted.

  In the second embodiment, the metal film 2 is composed of a first metal film made of Al and a second metal film 2b made of TiSi, and the second metal film 2b is provided on the oxide film 3 side. Therefore, the recording sensitivity can be improved.

(3) Third embodiment
Configuration of Write-once Type Optical Recording Medium A write-once type optical recording medium 10 according to the third embodiment has an inorganic recording film 6, a dielectric film 4, and a light transmission layer on a substrate 1 as in the first embodiment described above. It has a configuration in which the layers 5 are sequentially stacked. Since the material, thickness, etc. which comprise the board | substrate 1 and each layer laminated | stacked on it are the same as that of the above-mentioned 1st Embodiment, description is abbreviate | omitted.

  FIG. 2 is a plan view showing a write-once type optical recording medium according to a third embodiment of the present invention. As shown in FIG. 2, a lead-in area is provided on the inner peripheral portion of the write-once optical recording medium 10, and a user data area 13 is provided on the outer peripheral side of the lead-in area 12. The lead-in area 12 is provided with a BCA (Burst Cutting Area) 14 that is an identification information recording area.

  The user data area is an area for the user to record desired data. The lead-in area 12 is an area for recording information such as identification information (ID), an encryption key, and a composite key, and these information are recorded when the write-once optical recording medium 10 is manufactured. The BCA 14 is an area for recording identification information when the write-once type optical recording medium 10 is manufactured. The identification information is information unique to each medium, and is intended to prevent unauthorized copying, for example.

Write-once type optical recording medium manufacturing method The steps from the substrate forming step to the light transmitting layer forming step are the same as those in the first embodiment described above, and thus the description thereof will be omitted. The identification information recording process will be described.

  First, a recording apparatus used for recording identification information will be described with reference to FIG. As shown in FIG. 3, the recording apparatus includes a motor 21, an optical pickup 22, and a control circuit 23.

  The optical pickup 22 is an optical system for recording the identification information as a barcode by irradiating the write-once optical recording medium 10 with a laser beam 24. The wavelength of the laser beam 24 is preferably set to be approximately equal to the laser beam used for recording or reproducing user data. For example, when the write-once optical recording medium 10 is a medium on which user data is recorded or reproduced by blue laser light having a wavelength of 405 nm or the like, the wavelength of the laser light 22 of the optical pickup 22 is set to a wavelength of 350 nm to 450 nm. It is preferable to set the range. By using a laser in this wavelength range, a recording mark corresponding to the identification information can be satisfactorily recorded on the inorganic recording film 6 based on the same principle as recording user data.

  The control circuit 23 controls the entire recording apparatus. For example, focus control of the laser beam 24, position control of the optical pickup 22, rotation control of the motor 21, and generation of identification information are performed. The motor 21 rotates the write-once type optical recording medium 10 placed on a turntable (not shown).

Next, the identification information recording process using the above-described recording apparatus will be described.
First, the write-once type optical recording medium 10 is placed on a turntable (not shown) such that the light transmission layer 5 faces the optical pickup 22. Next, the motor 21 is driven to rotate the write-once type optical recording medium 10 at a predetermined speed.

  Then, after the optical pickup 22 is moved to the BCA 14 provided in the inner peripheral portion of the write-once type optical recording medium 10, the optical pickup 22 is driven and, for example, laser light modulated in a pulse shape according to identification information is emitted. Irradiation from the light transmission layer 5 side. Thus, in the portion of the inorganic recording film 6 irradiated with the laser beam 24, the oxygen of the oxide film 3 is separated, and a layer having a high oxygen concentration is formed on the metal film 2 side, and a layer having a low oxygen concentration. Is formed on the dielectric film 4 side. As a result, a recording mark corresponding to the identification information is formed, for example, in a barcode shape, and the identification information is recorded on the BCA. The wavelength of the laser beam used for forming the recording mark is preferably in the range of 350 nm to 450 nm as described above. Thus, the target write-once optical recording medium 10 is obtained.

  FIG. 4A shows an example of a recording mark formed on the BCA. FIG. 4B shows an example of a waveform of a reproduction signal when the identification information recorded in the BCA is reproduced. In FIG. 4A, the hatched portion indicates a recording mark, and this recording mark is formed by irradiating laser light modulated in a pulse shape.

  As shown in FIG. 4A, the identification information is recorded on the BCA as a bar-code striped pattern. In addition, since the reflectance decreases at the recording mark portion, the reproduction signal has a pulse-like waveform as shown in FIG.

  In the third embodiment, for example, identification information is recorded on the BCA 14 of the write-once type optical recording medium 10 using a laser beam having a wavelength of 350 nm to 450 nm. Therefore, the identification information is recorded on the inorganic recording film according to the same principle as recording user data. 6 can be recorded. Therefore, disturbance of the reproduction signal of identification information can be suppressed and a desired reproduction signal can be obtained. Further, in comparison with the case where the identification information is recorded by irradiating the laser beam from the light transmitting layer 5 side to melt and remove the laminated film on the substrate 1, signal defects caused by deformation of the substrate 1 are suppressed. be able to. Moreover, since there is little possibility of causing the corrosion of a laminated film, the outstanding storage stability can be obtained.

(4) Fourth embodiment
Configuration of Write-once Type Optical Recording Medium The write-once type optical recording medium 10 according to the fourth embodiment has a BCA, and identification information is recorded on the BCA 14. This identification information is formed by irradiating laser light from the substrate 1 side to melt and remove the laminated film laminated on the substrate 1. Since the configuration of the write-once type optical recording medium 10 other than this is the same as that of the above-described third embodiment, the description thereof is omitted.

Write-once type optical recording medium manufacturing method The steps from the substrate forming step to the light transmissive layer forming step are the same as those in the third embodiment described above, so the description thereof will be omitted. The identification information recording process will be described. The recording apparatus used for recording the identification information is the same as that of the above-described third embodiment except that the optical path length compensation element is provided in the optical pickup 22, and the description thereof is omitted. The optical path length compensation element provided in the optical pickup 22 is provided in consideration of irradiation with laser light from the side of the substrate 1 different from that in the third embodiment.

  First, the write-once type optical recording medium 10 is placed on a turntable (not shown) with the substrate 1 facing the optical pickup 22. Next, the motor 21 is driven to rotate the write-once type optical recording medium 10 at a predetermined speed.

  Then, after the optical pickup 22 is moved to the BCA 14 provided in the inner peripheral portion of the write-once type optical recording medium 10, the optical pickup 22 is driven and, for example, laser light modulated in a pulse shape according to identification information is emitted. Irradiate from the substrate 1 side. Thereby, in the portion of the inorganic recording film 6 irradiated with the laser beam 24, the metal film 2, the oxide film 2, and the dielectric film 5 laminated on the substrate 1 are melted and removed. As a result, a mark corresponding to the identification information is formed, for example, in a barcode shape, and the identification information is recorded on the BCA 14.

  The laser light is preferably near-infrared laser light or infrared laser light, for example, laser light having a wavelength of 800 nm. Further, it is preferable to set the optical head scanning speed at the time of laser light irradiation in the range of 5 m / s to 9 m / s and the laser power in the range of 3400 mW to 4000 mW. By setting this range, it is possible to suppress an abrupt increase in reflectance at the recording mark edge portion. Therefore, it is possible to reduce noise in the reproduction signal of the identification information.

  In the fourth embodiment, since the identification information is recorded by irradiating the BCA 14 with laser light from the side of the substrate 1 different from the time of recording / reproducing user data, the laser light is irradiated from the side of the light transmission layer 5. Have different light absorption characteristics, etc., so that it is possible to suppress deformation at the boundary portion of the mark, it is possible to suppress a part of the laminated film from remaining inside the BCA 14, and to suppress deformation of the substrate 1. Obtainable. That is, disturbance of the reproduction signal can be suppressed and a desired reproduction signal can be obtained.

  Further, since the metal film 2 can be directly irradiated with laser light, the laminated film on the substrate 1 can be effectively destroyed and removed. Note that, when laser light is irradiated from the light transmission layer 5 side, heat is diffused by the effect of absorption heat generation in the oxide film 3, so that it is considered that the laminated film on the substrate 1 cannot be destructively removed. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples. Moreover, the following Examples 1-2 respond | correspond to 1st Embodiment, and Examples 3-4 respond | correspond to 2nd Embodiment. Examples 5 to 6 correspond to the third embodiment. Examples 7 to 26 correspond to the fourth embodiment.

  As an embodiment of the present invention, a medium is designed and formed into a film on an optical system of a Blu-ray disc. The optical system of the Blu-ray disc uses a two-group objective lens having a numerical aperture of 0.85 and a blue-violet semiconductor laser light source having a wavelength of 400 nm to 410 nm. The application of the present invention is not limited to this optical system, and the same effect is expected even if the numerical aperture and wavelength are slightly different.

In the following examples, ODU-1000 (Blu-ray disc specification) manufactured by Pulstec Industrial Co., Ltd. was used as an evaluation device. The wavelength of this light source is 405 nm, and the NA of the objective lens is 0.85. The recording / reproducing conditions were 25 GB density, recording at 2 × speed (9.83 m / s), and playback at 1 × speed (4.92 m / s). The reproduction power was 0.35 mW, the reproduction signal was passed through a limit equalizer (pre-equalizer gain 7.1 dB), and the jitter was measured with a time interval analyzer (TA720 manufactured by Yokogawa Electric Corporation). The linear velocity of recording is 9.83 m / s (double speed recording), the linear velocity during reproduction is 4.92 m / s (single speed), and the channel bit length is 74.50 nm (recording density of 25 GB on a 12 cm diameter optical disk). I went there.
In addition, an ellipsometer (manufactured by Rudolf, trade name: Auto EL-462P17) was used to measure the absorption coefficient. The absorption coefficient is at a wavelength of 410 nm.

  First, a plurality of write-once optical recording media are obtained by changing the film thickness of the first metal film 2a made of TiSi and the second metal film 2b made of TiSi having a composition different from that of the first metal film 2a for each medium. 10 was prepared, and the film thicknesses of the first metal film 2a and the second metal film 2b were examined.

Example 1
FIG. 5 is a schematic cross-sectional view showing the film configuration of the write-once type optical recording medium of Example 1. In FIG. 5, illustration of the in-groove 11G and the on-groove 11L provided on the substrate 1 is omitted. In the sectional views of the following examples and comparative examples, the illustration of the in-groove 11G and the on-groove 11L provided on the substrate 1 is similarly omitted. The write once optical recording medium 10 of Example 1 has a configuration in which a TiSi film 2a, a TiSi film 2b, a GeO film 3, a ZnS-SiO ₂ film 4a, a SiN film 4b, and a light transmission layer 5 are sequentially laminated on a substrate 1. Have.

  Hereinafter, a method for manufacturing the write-once type optical recording medium 10 of Example 1 will be described with reference to FIG. First, the substrate 1 provided with the in-groove 11G and the on-groove 11L on one main surface was molded by an injection molding method. As the resin material, polycarbonate resin was used. Further, the rack pitch was set to 0.32 μm, the depth of the in-groove 11G was set to 21 nm, and the on-groove 11L was wobbled (meandered) to add address information.

Next, after evacuating the vacuum chamber, a TiSi target was sputtered while introducing Ar gas into the vacuum chamber, and a TiSi film 2a having a thickness of 17 nm was formed on the substrate 1. The composition ratio of Si in the TiSi film 2a was 20 atomic%.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.2Pa
Input power: 3kW
Ar gas flow rate: 30sccm

Next, after evacuating the vacuum chamber, a TiSi target was sputtered while introducing Ar gas into the vacuum chamber to form a TiSi film 2 having a thickness of 10 m on the substrate 1. The composition ratio of Si in the TiSi film 2b was 27 atomic%.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.2Pa
Input power: 3kW
Ar gas flow rate: 30sccm

Next, after evacuating the vacuum chamber, a Ge oxide target was sputtered while introducing Ar gas into the vacuum chamber, and a GeO film 3 having a thickness of 26.5 nm was formed on the TiSi film 2. . Note that the Ge oxide target had a composition in which the absorption coefficient k of the GeO film 3 was 0.4.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.2Pa
Input power: 2kW
Ar gas flow rate: 30sccm

Next, after evacuating the vacuum chamber, a ZnS—SiO ₂ target is sputtered while introducing a process gas into the vacuum chamber to form a 45 nm-thickness ZnS—SiO ₂ film 4 a on the GeO film 3. Filmed.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1 Pa
Input power: 1kW
Ar gas flow rate: 6sccm

Next, after evacuating the vacuum chamber, an Si gas was sputtered while introducing Ar gas and N 2 process gas into the vacuum chamber, and a SiN film 4b having a thickness of 7 nm was formed on the substrate 1.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.3 Pa
Input power: 4kW
Ar gas flow rate: 50 sccm
N ₂ gas flow rate: 37sccm

  Next, an annular polycarbonate sheet was bonded onto the substrate 1 with a pressure-sensitive adhesive (PSA) previously applied to one main surface of the sheet to form a light transmission layer 5 having a thickness of 100 μm. Thus, the target write-once optical recording medium 10 was obtained.

Example 2
FIG. 6 is a schematic cross-sectional view showing the film configuration of the write-once type optical recording medium of Example 2. The write-once type optical recording medium 10 of Example 2 includes a TiSi film 2a, a TiSi film 2b, a GeO film 3, a ZnS-SiO ₂ film 4a, a SiN film 4b, and a light transmission layer 5 in the same manner as in Example 1 described above. It has a configuration in which the substrate 1 is sequentially laminated. The write-once optical recording medium 10 of Example 2 is the same as that of Example 1 described above in that the thickness of the first metal film 2a is 22 nm and the thickness of the second metal film 2b is 5 nm. Is different.

  Hereinafter, a method for manufacturing the write-once type optical recording medium 10 of Example 3 will be described with reference to FIG. First, the substrate 1 was formed in the same manner as in Example 1. Next, the first metal film 2a, the second metal film 2a, and the TiSi film 2b are adjusted in the same manner as in Example 1 except that the film thicknesses of the TiSi film 2a and the TiSi film 2b are 22 nm and 5 nm, respectively. The second metal film 2b was sequentially laminated on the substrate 1. The subsequent steps were the same as in Example 1 described above, and the target write-once optical recording medium 10 was obtained.

Comparative Example 1
FIG. 7 is a schematic cross-sectional view showing the film configuration of the write-once type optical recording medium of Comparative Example 1. The write once optical recording medium 10 of Comparative Example 1 has a configuration in which a TiSi film 2b, a GeO film 3, a ZnS—SiO ₂ film 4a, a SiN film 4b, and a light transmission layer 5 are sequentially laminated on a substrate 1. The write-once type optical recording medium 10 of Comparative Example 1 is different from that of Example 1 described above in that the TiSi film 2a is omitted.

  Hereinafter, a method for manufacturing the write-once type optical recording medium of Comparative Example 1 will be described with reference to FIG. First, the substrate 1 was formed in the same manner as in Example 1. Next, a TiSiN film 2b having a film thickness of 27 nm was formed on the substrate 1 in the same manner as in Example 1 except that the film formation time was appropriately adjusted. The subsequent steps were the same as in Example 1 described above, and the target write-once optical recording medium 10 was obtained.

  Next, the optimum recording power Pwo, Leading jitter, Trailing jitter, and power margin of the write once optical recording media 10 of Examples 1 and 2 and Comparative Example 1 obtained as described above were measured. FIG. 8 shows the result. In FIG. 8, t1 and t2 indicate the thicknesses of the TiSi film 2a and the TiSi film 2b, respectively.

  Here, Leading jitter and Trailing jitter are the jitter values measured by the time interval analyzer after waveform equalization through a limit equalizer. The recording power Pwo is the recording light intensity when these are minimized. The jitter value in FIG. 8 is a value when recording is performed with the optimum recording power Pwo. The power margin is a value obtained by dividing the power range (peak to peak) where the jitter value is 8.5% or less by the optimum recording power Pwo.

  From the results shown in FIG. 8, the metal film 2 has a single-layer structure (t1 = 0) consisting only of the TiSi film 2b, and the metal film 2 compared to the comparative example 1 in which the Si composition ratio of the TiSi film 2b is 27 atomic%. In Examples 1-2, in which the Si composition ratio of the TiSi film 2a is 20 atomic% and less than that of the TiSi film 2b, the jitter value is kept good. It can be seen that the recording sensitivity can be improved.

  In Example 2 in which the thickness t2 of the TiSi film 2b is as thin as 5 nm, the power margin is narrow. This indicates that the power margin is approaching when the metal film 2 is a single layer of only the TiSi film 2a and the Si composition ratio of the TiSi film 2a is 20 atomic%.

  Therefore, a TiSi film 2b having an appropriate Si composition ratio is formed with a thickness of 6 nm or more adjacent to the GeO film 3 in order to obtain a desired power margin, and the Si composition ratio is TiSi to adjust the recording sensitivity. It shows that the recording sensitivity can be improved while maintaining the power margin and the bottom jitter by adjoining the TiSi film 2a with the TiSi film 2b, which is smaller than the film 2a.

  Next, a plurality of write-once optical recording media 10 are manufactured by changing the film thicknesses of the first metal film 2a made of Al and the second metal film 2b made of TiSi for each medium, and the first metal film The film thicknesses of 2a and second metal film 2b were examined.

Example 3
FIG. 9 is a schematic cross-sectional view showing the film configuration of the write-once type optical recording medium of Example 3. The write-once optical recording medium 10 of Example 3 has a configuration in which an Al film 2a, a TiSi film 2b, a GeO film 3, a ZnS-SiO ₂ film 4a, a SiN film 4b, and a light transmission layer 5 are sequentially laminated on the substrate 1. Have.

  Next, a method for manufacturing the write-once type optical recording medium of Example 3 will be described with reference to FIG. First, the substrate 1 was formed in the same manner as in Example 1.

Next, after evacuating the vacuum chamber, an Al target was sputtered while introducing Ar gas into the vacuum chamber, and an Al film 2 a having a thickness of 5 nm was formed on the substrate 1.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.2Pa
Input power: 2kW
Ar gas flow rate: 30sccm

Next, after evacuating the vacuum chamber, a TiSi target was sputtered while introducing Ar gas into the vacuum chamber, and a TiSi film 2 having a thickness of 20 m was formed on the substrate 1. The composition ratio of Si in the TiSi film 2b was 27 atomic%.
An example of film forming conditions in this film forming process is shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.2Pa
Input power: 3kW
Ar gas flow rate: 30sccm
Thereafter, the write-once type optical recording medium 10 was obtained in the same manner as in Example 1 described above.

Example 4
FIG. 10 is a schematic cross-sectional view showing the film configuration of the write-once type optical recording medium of Example 4. The write-once type optical recording medium 10 of this example 2 has an Al film 2a, a TiSi film 2b, a GeO film 3, a ZnS-SiO ₂ film 4a, a SiN film 4b, and a light transmission layer 5 in the same manner as in the above-mentioned example 3. It has a configuration in which the substrate 1 is sequentially laminated. The write-once optical recording medium 10 of Example 4 is the same as that of Example 3 described above in that the first metal film 2a has a thickness of 7 nm and the second metal film 2b has a thickness of 20 nm. Is different.

  Hereinafter, a method for manufacturing the write-once type optical recording medium 10 of Example 7 will be described with reference to FIG. First, the substrate 1 was molded in the same manner as in Example 3. Next, the Al film 2a and the TiSi film 2b are adjusted in the same manner as in Example 3 except that the film formation time is appropriately adjusted so that the film thicknesses of the Al film 2a and the TiSi film 2b are 7 nm and 20 nm, respectively. Were sequentially laminated on the substrate 1. The subsequent steps were the same as in Example 3 described above, and the target write-once type optical recording medium 10 was obtained.

Comparative Example 2
FIG. 11 is a schematic cross-sectional view showing the film configuration of the write-once type optical recording medium of Comparative Example 2. The write-once type optical recording medium 10 of Comparative Example 2 has a configuration in which a TiSi film 2b, a GeO film 3, a ZnS-SiO ₂ film 4a, a SiN film 4b, and a light transmission layer 5 are sequentially laminated on the substrate 1. The write-once optical recording medium 10 of Comparative Example 2 is different from that of Example 3 described above in that the Al film 2a is omitted.

  Next, a method for manufacturing the write-once type optical recording medium of Comparative Example 1 will be described with reference to FIG. First, the substrate 1 was molded in the same manner as in Example 3. Next, a TiSiN film 2b having a film thickness of 27 nm was formed on the substrate 1 in the same manner as in Example 1 except that the film formation time was appropriately adjusted. The subsequent steps were the same as in Example 3 described above, and the target write-once type optical recording medium 10 was obtained.

  Next, the optimum recording power Pwo, Leading jitter, Trailing jitter, and power margin of the write-once type optical recording media 10 of Examples 3 to 4 and Comparative Example 2 obtained as described above were measured. FIG. 12 shows the result. In FIG. 12, t3 and t4 indicate the thicknesses of the TiSi film 2a and the TiSi film 2b, respectively. Here, the optimum recording power Pwo, Leading jitter, Trailing jitter, and power margin are the same as those in the first and second embodiments.

  From the results shown in FIG. 12, when the Al film 2a of 5 nm is formed, the recording sensitivity is dramatically improved, while the power margin is only slightly deteriorated as compared with the case where the Al film 2a is not formed. ing. Also, the bottom jitter is almost the same as when the Al film 2a is not formed. When the thickness of the Al film 2a is further increased to 7 nm, the recording sensitivity is deteriorated as compared with the case where the thickness of the Al film 2a is 5 nm. Although detailed explanation is omitted, when the thickness of the Al film 2a is made thicker than 7 nm, the jitter is deteriorated and good recording is not performed.

  Therefore, by providing the Al film 2a having a thickness of 7 nm or less adjacent to the TiSi film 2b, the recording sensitivity can be improved without causing deterioration of jitter and power margin.

Next, Examples 5 to 6 corresponding to the third embodiment will be described.
(3) Examination of BCA formation method by blue laser Next, the BCA formation method by blue laser was examined. The contents of this study will be described below.

Example 5
The write-once optical recording medium 10 of Example 5 has a configuration in which a TiSi film 2, a GeO film 3, a ZnS—SiO ₂ film 4a, a SiN film 4b, and a light transmission layer 5 are sequentially stacked on a substrate 1.

  Hereinafter, a method for manufacturing the write-once type optical recording medium 10 of Example 5 will be described. First, the substrate 1 provided with the in-groove 11G and the on-groove 11L on one main surface was molded by an injection molding method. As the resin material, polycarbonate resin was used. Further, the track pitch was set to 0.32 μm, the depth of the in-groove 11G was set to 21 nm, and the on-groove 11L was wobbled (meandered) to add address information.

Next, after evacuating the vacuum chamber, a TiSi target was sputtered while introducing Ar gas into the vacuum chamber, and a TiSi film 2 having a thickness of 27 nm was formed on the substrate 1. The composition ratio of Si in the TiSi film 2 was 27 atomic%.
The film forming conditions in this film forming process are shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.2Pa
Input power: 3kW
Ar gas flow rate: 30sccm

Next, after evacuating the vacuum chamber, a Ge oxide target was sputtered while introducing Ar gas into the vacuum chamber to form a 26 nm-thick GeO film 3 on the TiSi film 2. The oxygen composition of the Ge oxide target was adjusted so that the absorption coefficient k of the GeO film 3 was 0.40.
The film forming conditions in this film forming process are shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.2Pa
Input power: 2kW
Ar gas flow rate: 30sccm

Next, after evacuating the vacuum chamber, a ZnS—SiO ₂ target is sputtered while introducing Ar gas into the vacuum chamber, and a ZnS—SiO ₂ film 4 a having a thickness of 45 nm is formed on the GeO film 3. did.
The film forming conditions in this film forming process are shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.1 Pa
Input power: 1kW
Ar gas flow rate: 6sccm

Next, after evacuating the inside of the vacuum chamber, a Si target was sputtered while introducing Ar gas and N ₂ gas into the vacuum chamber, and a SiN film 4b having a thickness of 7 nm was formed on the substrate 1.
The film forming conditions in this film forming process are shown below.
Degree of vacuum: 5.0 × 10 ⁻⁵ Pa
Atmosphere: 0.3 Pa
Input power: 4kW
Ar gas flow rate: 50 sccm
N ₂ gas flow rate: 37sccm

  Next, an annular polycarbonate sheet was bonded onto the substrate 1 with a pressure-sensitive adhesive (PSA) previously applied to one main surface of the sheet to form a light transmission layer 5 having a thickness of 0.1 mm. .

  Next, a laser beam having a wavelength of 405 nm was modulated in a pulse shape and irradiated to the BCA from the light transmission layer 5 side. As a result, a write-once optical recording medium 10 in which a barcode-like recording mark was formed on the BCA was obtained. The beam width was about 5 μm, the linear velocity was 10 m / s, the laser irradiation power was 160 mW, and the beam feed amount per rotation was 2 μm.

Example 6
Next, the write-once type optical recording medium 10 in which the barcode was formed on the BCA was obtained in the same manner as in Example 5 except that the recording mark was formed by irradiating the laser beam with a wavelength of 800 nm. .

  Next, the signals recorded in the BCAs of Examples 5 to 6 obtained as described above were reproduced, and the reproduced signals were evaluated.

  FIG. 13A shows an image of a recording mark formed on the BCA. FIG. 13B shows the waveform of the reproduction signal of the fifth embodiment. FIG. 13C shows the waveform of the reproduction signal of Example 6. In FIG. 13B and FIG. 13C, illustration of minute noise is omitted for easy comparison between the fifth embodiment and the sixth embodiment.

  Comparison of FIG. 13B and FIG. 13C reveals the following. That is, in Example 6, there is a region where the reflectance suddenly increases at the boundary portion of the recording mark, whereas in Example 5, there is no region where the reflectance suddenly increases at the boundary portion of the recording mark. I understand. This is presumably because the 800 nm band laser has wavelength dependence, so that it is difficult to record information signals on the BCA in the write-once optical recording medium 10 optimized for recording and reproduction in the 400 nm band. Although not shown, in Example 5, the overall signal level of the BCA section was also relatively uniform.

Next, Examples 7 to 26 corresponding to the fourth embodiment will be described.
(4) Examination of BCA Formation Method Using Infrared Laser Next, a BCA formation method using an infrared laser was examined. The contents of this study will be described below.

Examples 7-11
First, a plurality of write-once type optical recording media 10 were obtained in the same manner as in Example 5 described above. Next, the optical head scan speed is changed in the range of 3 m / s to 11 m / s for each of the plurality of write-once optical recording media 10 obtained as described above, and laser light with an output power of 4000 mW and a wavelength of 810 nm is pulsed. The BCA was irradiated from the substrate 1 side. As a result, the TiSi film 2, the GeO film 3, the ZnS-SiO ₂ film 4a, and the SiN film 4b were melted and removed to obtain a plurality of write-once type optical recording media 10 in which barcode-like recording marks were formed on the BCA. The beam width was about 30 μm, the laser irradiation power was 4000 mW, and the beam feed amount per rotation was 2 μm.

Examples 12-16
Except for the output power of 3400 mW, a plurality of write-once optical recording media 10 in which barcode-like recording marks were formed on BCA were obtained in the same manner as in Examples 7 to 11 described above.

Examples 17-21
Except for irradiating the laser beam to the BCA from the light transmission layer side, all of the write-once optical recording media 10 in which barcode-like recording marks were formed on the BCA were obtained in the same manner as in Examples 7-11. .

Examples 22-26
Except for irradiating the laser beam to the BCA from the light transmission layer side, all of the write-once optical recording media 10 in which barcode-shaped recording marks were formed on the BCA were obtained in the same manner as in Examples 12-16. .

  In Examples 7 to 26 described above, an infrared laser with a wavelength of 810 nm was used from a practical viewpoint. However, the wavelength of the laser beam can be selected as appropriate, and the infrared laser is limited to one with a wavelength of 810 nm. For example, the thing of the wavelength range of 720 nm-2500 nm can be used. The reason why laser light having a wavelength of 810 nm is used in Examples 7 to 26 is as follows. That is, it is difficult to obtain a laser power capable of destructively removing the laminated film on the substrate 1 with a laser having a wavelength other than 810 nm. That is, since the laser power of the 650 nm band and the 400 nm band is insufficient, it is difficult to destructively remove the laminated film.

  Next, the signals recorded in the BCA of Examples 7 to 26 obtained as described above were reproduced, and the reproduced signals were evaluated.

  FIG. 14 shows evaluation results of BCA reproduction signals of Examples 7-11. FIG. 15 shows the evaluation results of the BCA reproduction signals of Examples 12-16. FIG. 16 shows evaluation results of BCA reproduction signals of Examples 17-21. FIG. 17 shows the evaluation results of the BCA reproduction signals of Examples 22 to 26. FIG. 18 shows reproduction signals of Examples 7 to 11. FIG. 19 shows reproduction signals of Examples 12-16. FIG. 20 shows reproduction signals of Examples 17-21. FIG. 21 shows reproduction signals of Examples 22 to 26. In the evaluation result columns of FIGS. 14 to 17, “◯” indicates a reproduction signal in which the signal level of the BCA portion is relatively uniform and there is no region where the reflectivity suddenly increases at the boundary portion of the recording mark. “×” indicates a reproduction signal in which the signal level of the BCA portion is not uniform and there is a region where the reflectance rapidly increases at the boundary portion of the recording mark. Further, in each of FIGS. 18A to 21E, the signal waveform shown in the lower part is an enlarged part of the signal waveform shown in the upper part. A to E correspond to signal waveforms of the write-once type optical recording medium 10 in which BCA is formed at a scanning speed of 3 m / s to 11 m / s, respectively.

14 to 17, when the laser beam is irradiated from the light transmission layer 5 side, the signal level of the BCA portion is not uniform regardless of the optical head scan speed and the laser power, and the boundary portion of the recording mark It can be seen that there is a region where the reflectance rapidly increases.
On the other hand, when the laser beam is irradiated from the substrate 1 side, the signal level of the BCA section can be increased by setting the optical head scan speed in the range of 5 m / s to 9 m / s and the laser power in the range of 3400 mW to 4000 mW. It can be seen that there is no region where the reflectivity is abruptly high at the boundary portion of the recording mark.

  Although the first to fourth embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described first to fourth embodiments, and is based on the technical idea of the present invention. Various variations based on this are possible.

  For example, the numerical values given in the first to fourth embodiments are merely examples, and different numerical values may be used as necessary.

  In the first to fourth embodiments described above, the case where the metal film 3 is made of Ti has been described. However, even if the metal film 3 is made of a metal material that exhibits a photocatalytic effect other than Ti, the above-described case is possible. It is considered that a write-once type optical recording medium capable of recording an information signal can be obtained as in the first to fourth embodiments.

It is a schematic sectional drawing which shows one structural example of the write-once type optical recording medium by 1st Embodiment of this invention. It is a top view which shows the write-once type | mold optical recording medium by 3rd Embodiment of this invention. It is a block diagram which shows the structure of the recording device used for recording the specific information with respect to the write-once type optical recording medium by 3rd Embodiment of this invention. 4A is a schematic diagram showing an example of a recording mark formed on the BCA, and FIG. 4B is an abbreviation showing an example of a waveform of a reproduction signal when the unique information recorded on the BCA is reproduced. FIG. 3 is a schematic cross-sectional view showing a film configuration of a write-once optical recording medium of Example 1. FIG. 6 is a schematic cross-sectional view showing a film configuration of a write-once optical recording medium of Example 2. FIG. 6 is a schematic cross-sectional view showing a film configuration of a write-once type optical recording medium of Comparative Example 1. FIG. The measurement results of the optimum recording power Pwo, Leading jitter, Trailing jitter, and power margin of Examples 1 and 2 and Comparative Example 1 are shown. 6 is a schematic cross-sectional view showing a film configuration of a write-once type optical recording medium of Example 3. FIG. 6 is a schematic cross-sectional view showing a film configuration of a write-once optical recording medium of Example 4. FIG. 6 is a schematic cross-sectional view showing a film configuration of a write-once type optical recording medium of Comparative Example 2. FIG. The measurement results of optimum recording power Pwo, Leading jitter, Trailing jitter, and power margin of Examples 3 to 4 and Comparative Example 2 are shown. FIG. 13A is a schematic diagram showing the waveform of the reproduction signal of Example 5, and FIG. 13B is a schematic diagram showing the waveform of the reproduction signal of Example 6. It is a table | surface which shows the evaluation result of the reproduction signal of Examples 7-11. It is a table | surface which shows the evaluation result of the reproduction signal of Examples 12-16. It is a table | surface which shows the evaluation result of the reproduction signal of Examples 17-21. It is a table | surface which shows the evaluation result of the reproduction signal of Examples 22-26. It is a basic diagram which shows the reproduction signal of BCA of Examples 7-11. It is a basic diagram which shows the reproduction signal of BCA of Examples 12-16. It is a basic diagram which shows the reproduction signal of BCA of Examples 17-21. It is a basic diagram which shows the reproduction signal of BCA of Examples 22-26.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Metal film 2a 1st metal film 2b 2nd metal film 3 Oxide film 4 Dielectric film 5 Light transmission layer 6 Inorganic recording film 10 Write-once type optical recording medium

Claims (18)

A write once optical recording medium having an inorganic recording film,
The inorganic recording film is
An oxide film made of germanium oxide;
An adjacent film adjacent to the oxide film,
The adjacent membrane is
A first adjacent film made of titanium and silicon;
A second adjacent film made of titanium and silicon having a composition different from that of the first adjacent film,
Of the first and second adjacent films, the second adjacent film is provided on the oxide film side,
It said first and second respectively TiSi _x composition of the adjacent layer, when expressed as TiSi _y, recordable optical recording medium in which the TiSi _x, TiSi _y is characterized by satisfying the relation of x <y. Having an identification information recording area in which identification information is recorded;
2. The write-once type optical recording medium according to claim 1, wherein the identification information is recorded by forming a recording mark corresponding to the identification information on the oxide film. Having an identification information recording area in which identification information is recorded;
2. The write-once type optical recording medium according to claim 1, wherein the identification information is recorded by removing the inorganic recording film with a pattern corresponding to the identification information. A method for producing a write-once optical recording medium having an inorganic recording film,
Forming an oxide film made of a germanium oxide;
Forming an adjacent film made of metal, and
The step of forming the adjacent film includes
Forming a first adjacent film made of titanium and silicon;
Forming a second adjacent film made of titanium and silicon having a composition different from that of the first adjacent film,
In the film formation step of the oxide film and the adjacent film, the oxide film and the second adjacent film are formed adjacent to each other,
A method for manufacturing a write-once optical recording medium, wherein the composition of the first and second adjacent films is expressed as TiSix and TiSiy, respectively, and the TiSix and TiSiy satisfy the relationship x <y.   3. The write-once type optical recording medium manufacturing method according to claim 2, wherein the film forming steps of the oxide film and the adjacent film are continuously performed.   The write-once type according to claim 4, further comprising a step of recording identification information by irradiating the write-once type optical recording medium with a laser beam having a wavelength of 350 nm to 450 nm from the oxide film side. Manufacturing method of optical recording medium.   5. The method of manufacturing a write-once optical recording medium according to claim 4, further comprising a step of recording identification information by irradiating the write-once optical recording medium with laser light from the adjacent film side.   8. The write-once light according to claim 7, wherein the write-once optical recording medium is irradiated with the laser light under conditions of an optical head scan speed of 5 m / s to 9 m / s and a laser power of 3400 mW to 4000 mW. A method for manufacturing a recording medium. A write once optical recording medium having an inorganic recording film,
The inorganic recording film is
An oxide film made of germanium oxide;
An adjacent film adjacent to the oxide film,
The adjacent membrane is
A first adjacent film made of aluminum;
A second adjacent film made of titanium,
A write-once type optical recording medium, wherein the second adjacent film of the first and second adjacent films is provided on the oxide film side.   The write-once type optical recording medium according to claim 9, wherein the first adjacent film further contains Si.   The write-once type optical recording medium according to claim 9, wherein the first adjacent film has a thickness of 7 mm or less. Having an identification information recording area in which identification information is recorded;
The write-once type optical recording medium according to claim 9, wherein the identification information is recorded by forming a recording mark corresponding to the identification information on the oxide film. Having an identification information recording area in which identification information is recorded;
The write-once type optical recording medium according to claim 9, wherein the identification information is recorded by removing the inorganic recording film in a pattern corresponding to the identification information. A method for producing a write-once optical recording medium having an inorganic recording film,
Forming an oxide film made of a germanium oxide;
Forming an adjacent film made of metal, and
The step of forming the adjacent film includes
Forming a first adjacent film made of aluminum;
Forming a second adjacent film made of titanium,
In the film formation step of the oxide film and the adjacent film, the oxide film and the second adjacent film are formed adjacent to each other,
In the film forming process of the oxide film and the adjacent film, the oxide film and the adjacent film are formed so as to be adjacent to each other.   15. The method for manufacturing a write-once optical recording medium according to claim 14, wherein the oxide film and the adjacent film are continuously formed.   The write-once type according to claim 14, further comprising a step of recording identification information by irradiating the write-once type optical recording medium with a laser beam having a wavelength of 350 nm to 450 nm from the oxide film side. Manufacturing method of optical recording medium.   15. The method of manufacturing a write once optical recording medium according to claim 14, further comprising a step of recording identification information by irradiating the write once optical recording medium with laser light from the adjacent film side.   18. The write-once light according to claim 17, wherein the write-once optical recording medium is irradiated with the laser light under conditions of an optical head scan speed of 5 m / s to 9 m / s and a laser power of 3400 mW to 4000 mW. A method for manufacturing a recording medium.

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