JP2009054248A - Method of manufacturing optical recording medium, and optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical recording medium for manufacturing the optical recording medium having uniform recording characteristics. <P>SOLUTION: A first dielectric layer 12 is formed on one side of a recording layer 13 while a portion of particles emitted from a sputtering target including a metal oxide such as ZnS-SiO<SB>2</SB>toward a disk substrate 11 which is rotated is shielded by a shielding member 50A formed based on a prescribed film thickness distribution. Thereby, the first dielectric layer 12 having film thickness distribution depending on recording characteristics of the recording layer 13 is formed and as a result, recording characteristics of an optical disk 10 can be uniformed. The optimum recording power of the optical disk 10 is prevented from being varied in terms of position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical recording medium manufacturing method and an optical recording medium, and more particularly to an optical recording medium manufacturing method having a protective layer having a predetermined film thickness distribution and an optical recording medium on which information is recorded.

  In recent years, standards for next-generation optical disks with recording capacities exceeding conventional optical disks such as CD (Compact Disk) and DVD (Digital Versatile Disk) have been proposed. For example, next-generation optical discs such as HD DVD (High Definition DVD) and BD-R (Blu-ray Disc Recordable) have appeared (for example, Patent Document 1 and Patent Document 1). Patent Document 2).

  The optical disc described in Patent Document 1 includes bismuth oxide, B, P, Ga, As, Se, Tc, Pd, Ag, Sb, Te, W, Re, Os, Ir, Pt, Au, Hg, Tl, Po. , At, Cd is a write-once type optical recording medium having a recording layer containing at least one element selected from At, Cd. The optical disc described in Patent Document 2 is a write-once type optical recording medium in which the storage stability of the recording layer is improved by setting the atomic ratio of Bi and B contained in the recording layer to an optimum range. is there. Further, in Patent Document 2, when the recording layer containing Bi, B, and O contains an oxide in an oxygen deficient state with less oxygen than the stoichiometric composition, the recording sensitivity of the recording layer is improved. Are listed.

JP 2006-247897 A JP 2006-213970 A

  The composition of the recording layer formed on the disk substrate depends on conditions such as the state of the sputter target, the easiness of sputtering of the elements contained in the sputter target, the input power during film formation, the argon flow rate during film formation, It is very difficult to form a recording layer having a uniform oxygen deficiency state. For this reason, when the recording layer is formed on the disk substrate by the conventional method, the recording characteristics of the optical disk differ depending on the position in the radial direction.

  The present invention has been made under such circumstances, and a first object thereof is to provide an optical recording medium manufacturing method capable of manufacturing an optical recording medium with uniform recording characteristics. .

  A second object of the present invention is to provide an optical recording medium having uniform recording characteristics.

  From a first viewpoint, the present invention is a method for manufacturing an optical recording medium having a recording layer formed on a disk substrate and a protective layer formed on one side of the recording layer with a predetermined film thickness distribution. An injection step of injecting particles emitted from a sputter target including a material constituting the protective layer onto the rotating disk substrate; and a part of the injected particles based on the predetermined film thickness distribution And a shielding step for shielding. An optical recording medium manufacturing method comprising:

  According to this, the protective layer has a predetermined film thickness distribution on the disk substrate by blocking particles ejected from the sputter target toward the rotating substrate based on the predetermined film thickness distribution. A protective layer is formed. Therefore, by adjusting the film thickness distribution of the protective layer formed on one side of the recording layer according to the recording characteristics of the recording layer to obtain a predetermined film thickness distribution, the recording characteristics of the optical disc can be made uniform. It becomes possible to plan.

  From a second viewpoint, the present invention is an optical recording medium manufactured by the method for manufacturing an optical recording medium of the present invention. According to this, the optical recording medium is manufactured by the optical recording medium manufacturing method of the present invention. Therefore, the optical recording medium has uniform recording characteristics over the entire recording surface, and information can be recorded and reproduced with high accuracy.

<< First Embodiment >>
A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view showing an optical disc 10 according to the first embodiment. As an example, the optical disc 10 is an HD DVD-R capable of recording and reproducing information with a laser beam having a wavelength of about 400 nm, and as shown in FIG. A disk substrate 11 is formed. The disk substrate 11 is a circular plate-shaped substrate having a diameter of 120 mm and a thickness of about 1 mm, for example. The recording area 10a corresponds to the laser beam.

  FIG. 2 is a view showing a cross section of the optical disc 10. As shown in FIG. 2, in the recording area 10a, the first dielectric layer 12, the recording layer 13, the second dielectric layer 14, the reflective layer 15, and the overcoat layer 16 are laminated on the surface of the disk substrate 11. A dummy substrate 18 is bonded to the surface of the disk substrate 11 on which the overcoat layer 16 is formed via an adhesive layer 17.

  The disk substrate 11 is manufactured, for example, by injection molding a polycarbonate resin, and a spiral guide groove (groove groove) is formed on the upper surface thereof.

  The recording layer 13 includes a dye material, such as Bi oxide, and an oxide of at least one element selected from B, Cu, Fe, Ge, and Zn. The recording layer 13 can be formed by sputtering the dye material on the surface of the disk substrate 11 on which the first dielectric layer 12 is formed.

  Each of the first dielectric layer 12 and the second dielectric layer 14 functions as a protective film for protecting the recording layer 13 and is formed above and below the recording layer 13, respectively. These dielectric layers 12 and 14 can be formed by sputtering a metal or semiconductor oxide on the surface of the disk substrate 11 or the surface of the disk substrate 11 on which the recording layer 13 is formed. As a material of each dielectric layer 12, 14, a metal oxide such as ZnS-SiO2 can be used.

  The reflection layer 15 includes a metal material having a high reflectance with respect to laser light, such as AlTi.

  The overcoat layer 16 is formed by spin-coating a surface of the disk substrate 11 on which the above layers 12 to 15 are laminated, and curing the material by irradiating the material with ultraviolet light. It is formed by letting.

  The dummy substrate 18 is made of the same material as the disk substrate 11 and is attached to the surface of the disk substrate 11 on which the overcoat layer 16 is formed by an adhesive. The adhesive layer 17 is a layer formed by curing an adhesive that bonds the dummy substrate 18 and the disk substrate 11.

  The layer formed in the recording area 10a may include layers other than the first dielectric layer 12, the recording layer 13, the second dielectric layer 14, and the reflective layer 15 described above.

  Next, a sputtering apparatus 100 for forming the first dielectric layer 12, the recording layer 13, the second dielectric layer 14, and the reflective layer 15 on the disk substrate 11 of the optical disk 10 configured as described above will be described.

  FIG. 3 is a diagram illustrating a schematic configuration of the sputtering apparatus 100. As shown in FIG. 3, the sputtering apparatus 100 rotates the disk substrate 11 of the optical disk 10 described above so that the sputtering cathode 21 on which the sputtering target 25 is mounted via the backing plate 23 and the sputtering cathode 21 face each other. The rotating unit 30 that can be held, the annular member 35 that supports the shielding member 50A between the rotating unit 30 and the sputtering cathode 21, the vacuum chamber 20A that accommodates the above parts, and the casing 20B that is fixed to the + X side of the vacuum chamber 20A The magnet 40 is housed inside the casing 20B, and includes a control device (not shown) for controlling each of the above parts.

  As an example, the vacuum chamber 20A is a cylindrical chamber whose inside is maintained in a predetermined vacuum state and whose X-axis direction is a generatrix direction.

  The sputtering cathode 21 is a member having a T-shaped ZX cross section, a circular plate-like electrode portion facing the disk substrate 11 held by the rotary unit 30, and extending from the electrode portion in the + X direction, It has two parts of the extended part drawn in from the inside of 20A to the inside of casing 20B.

  A sputtering target 25 is mounted on the surface of the electrode portion on the −X side via a backing plate 23. As an example, the cooling water is circulated inside the backing plate 23, and heat exchange is performed between the sputtering target 25 and the sputtering cathode 21 and the cooling water, thereby suppressing the temperature rise of the sputtering target 25 and the sputtering cathode 21. To do. Further, the sputter target 25 is selected according to each layer 12 to 15 formed on the disk substrate 11 and attached to the sputtering cathode 21.

  The rotation unit 30 includes a circular plate-like substrate holder 31 that holds the disk substrate 11 by suction, and a rotation mechanism 32 that rotates the substrate holder 31 around an axis parallel to the X axis at a predetermined rotation speed. .

  4A is a perspective view showing the substrate holder 31 together with the disk substrate 11, and FIG. 4B is a view of the substrate holder 31 and the disk substrate 11 in FIG. 4A viewed from the −Y side. It is.

  The disk substrate 11 is held by the substrate holder 31 with its center positioned at the rotation center of the substrate holder 31. 4A and 4B, the area surrounding the circular opening 11a on the surface of the disk substrate 11 (the surface on the + X side) is shielded by the inner peripheral mask 34. As shown in FIG. Since the outer edge of the surface of the disk substrate 11 is shielded by the outer peripheral mask 33, only the recording area 10 a on the surface of the disk substrate 11 shown in FIG. 1 is exposed to the sputter target 25.

  The outer peripheral mask 33 that shields the disk substrate 11 has a tapered shape in which a portion covering the surface of the disk substrate 11 becomes thinner toward the inner peripheral portion of the disk substrate 11. The inner mask 34 has a tapered shape in which a portion covering the surface of the disk substrate 11 becomes thinner toward the outer periphery of the disk substrate 11.

  FIG. 5A is a perspective view showing the annular member 35 and the vicinity thereof, and FIG. 5B is a side view showing the annular member 35 and the vicinity thereof. The annular member 35 is an annular member made of, for example, aluminum and having an inner diameter larger than the outer diameter of the disk substrate 11. The annular member 35 is arranged in the vicinity of the + X side of the substrate holder 31 as shown in FIGS. 5A and 5B by fixing the outer peripheral surface to the inner wall surface of the vacuum chamber 20A. Yes.

  The shielding member 50A is a plate-like member whose longitudinal direction is the Z-axis direction. As shown in FIGS. 5A and 5B, the shielding member 50 </ b> A is positioned at the center of rotation of the substrate holder 31, and both ends thereof are, for example, screws on the upper surface of the annular member 35. It is fixed by etc.

  FIG. 6 is a diagram schematically showing the shielding member 50 </ b> A and the recording area 10 a formed on the disk substrate 11. The above-described shielding member 50A has the center coincident with the center of the disk substrate 11 held by the substrate holder 31, and the shape thereof is from a position corresponding to the center portion of the disk substrate 11, as shown in FIG. It spreads at a constant rate in the radial direction of the disk substrate 11 and corresponds to a position on the circumference of the circle having the radius R1 from a position on the disk substrate 11 corresponding to the circumference of the circle having the radius R2. It has a shape that converges at a certain rate over the position.

  That is, the shielding member 50A has a fan shape with an angle of θ1 from the inner peripheral edge of the recording area 10a to the position corresponding to the position on the circumference of the circle having the radius R2 in relation to the recording area 10a on the disk substrate 11. The shielding member 50A is formed in a shape that converges at a predetermined ratio from a position corresponding to the position on the circumference of the circle having the radius R2 in the region 10a to a position corresponding to the position on the circumference of the circle having the radius R1. And a gap GP defined by the outer edge of the recording area 10a.

  Here, a portion that spreads out in a fan shape from the inner periphery of the recording area 10a is simply abbreviated as a fan-shaped portion for convenience of explanation. In the first embodiment, the angle θ1 of the fan-shaped outer edge of the shielding member 50A is 42.6 degrees, the value of the radius R1 is 59.5 mm, the value of the radius R2 is 55 mm, and the value of the radius R3 is 25 mm. It has become.

  Further, the front and back surfaces of the shielding member 50A are subjected to a thermal spraying process using aluminum, for example. Note that the thermal spraying is one of surface treatment techniques for forming a film by spraying a molten or softened coating material (metal, ceramic, plastic, or the like) onto an object. By performing thermal spraying on the shielding member 50A, a porous film having a rough surface with a structure in which fine particles overlap each other can be formed on the surface. As a general thermal spraying method, arc spraying, flame spraying, plasma spraying, and the like can be cited, and they are properly used depending on the type of coating material and the type of object.

  Returning to FIG. 1, the magnet 40 is an annular electromagnet into which the extending portion of the sputtering cathode 21 is inserted, and is accommodated in a casing 20B fixed to the vacuum chamber 20A. The magnet 40 adjusts the plasma density inside the vacuum chamber 20A by controlling the magnetic field inside the vacuum chamber 20A.

  The control device (not shown) is, for example, a control computer configured to include a CPU and a memory storing programs and parameters for controlling the above-described units. This control device controls each of the above parts based on a command from a host device or a user.

  Next, a method for forming a thin film on the disk substrate 11 using the sputtering apparatus 100 described above will be described. It is assumed that the plasma density inside the vacuum chamber 20A is adjusted to a state optimal for sputtering by the gnet 40.

  In the sputtering apparatus 100, when the control device receives an operation start command from the host device or the user, the substrate holder 31 is rotated at a predetermined number of rotations by the rotation mechanism 32. As a result, the disk substrate 11 from which only the recording area 10a is exposed is rotated at a predetermined rotational speed.

  When the sputtering cathode 21 is energized, particles serving as a raw material for the thin film formed on the disk substrate 11 are ejected from the sputtering target 25. A part of the ejected particles is shielded by the shielding member 50 </ b> A, and the rest reaches and adheres to the recording area 10 a on the surface of the rotating disk substrate 11, thereby forming a thin film on the surface of the disk substrate 11.

  In the first embodiment, the first dielectric layer 12 is formed in a state where a part of the recording area 10a is shielded using the shielding member 50A, and then the shielding member 50A is removed from the sputtering apparatus 100. Then, the recording layer 13, the second dielectric layer 14, and the reflective layer 15 are sequentially formed in a state where the recording area 10a is completely exposed.

  In the optical disk 10, a dummy substrate 18 is further bonded to the surface of the disk substrate 11 on which the first dielectric layer 12, the recording layer 13, the second dielectric layer 14, and the reflective layer 15 are formed as described above. Will be completed.

Examples of the present invention will be described below. In addition, an Example is an example and this invention is not limited to the case of an Example.
Example 1
A disk substrate 11 having a thickness of 0.6 mm and a guide groove having a track pitch of 0.4 μm formed on the surface by melting and injection molding a polycarbonate pellet, which is a raw material of the disk substrate 11 of the optical disk, is formed. Formed.

Next, after injection molding, ZnS—SiO ₂ (80:20 mol%) is adhered to the surface of the sufficiently cooled disk substrate 11 using the sputtering apparatus 100 to form a first dielectric layer 12 having a thickness of 60 nm. did. FIG. 7 shows the relative value of the film thickness with respect to the radial position of the first dielectric layer 12 formed in the recording area 10a of the disk substrate 11 (hereinafter referred to as the film thickness relative value) by the sputtering apparatus 100 provided with the shielding member 50A. It is a figure which shows. Thickness relative value represented by the curve L _N in the figure, in a state of removing the shielding member 50A, a film thickness relative values to form the disk substrate 11 dielectric layer, the thickness relative shown by curve L _A The value is a relative thickness value of the thin film formed on the disk substrate 11 in a state where a part of the particles from the sputtering target 25 is shielded by using the shielding member 50A as described above. The first dielectric layer thickness relative value of 12 according to this embodiment, as shown by the curve L _A, thickness relative value of a position near the 58mm from the center of the disk substrate 11 was about 1.08 . The film thickness relative value refers to the relative value of the film thickness at each position when the film thickness at a position 40 mm from the center of the disk substrate 11 (position on the circumference having a radius of 40 mm) is 1.

Consisting of the as shown by the first dielectric layer having a thickness relative value curve L _A, the particles from the sputtering target 25 is defined by an outer edge and the shielding member 50A of the recording area 10a shown in FIG. 6 This is because it passes through the gap GP and turns around toward the center of the disk substrate 11, and the particles are deposited on the surface of the disk substrate 11 from a little inside the circle with the radius R2 to a region near the circle with the radius R1.

Next, Bi ₂₀₃ -B ₂₀₃ (2: 1 mol%) was attached to the surface of the disk substrate 11 on which the first dielectric layer 12 was formed using the sputtering apparatus 100 to form the recording layer 13 having a thickness of 15 nm. .

Next, ZnS—SiO ₂ (80:20 mol%) was attached to the surface of the disk substrate 11 on which the recording layer 13 was formed using the sputtering apparatus 100 to form a second dielectric layer 14 having a thickness of 20 nm. .

  Next, AlTi (99: 1 wt%) was attached to the surface of the disk substrate 11 on which the second dielectric layer 14 was formed by using the sputtering apparatus 100 to form the reflective layer 15 having a thickness of 40 nm.

  Next, an ultraviolet curable material was spin coated on the surface of the disk substrate 11 on which the reflective layer 15 was formed, and the overcoat layer 16 was formed by curing the material.

Next, a dummy substrate 18 having a thickness of 0.6 mm was bonded to the surface of the disc substrate 11 on which the overcoat layer 16 was formed, thereby manufacturing the optical disc 10 having a thickness of about 1.2 mm.
Example 2
A disk substrate 11 having a thickness of 0.6 mm and a guide groove having a track pitch of 0.4 μm formed on the surface by melting and injection molding a polycarbonate pellet, which is a raw material of the disk substrate 11 of the optical disk, is formed. Formed.

Next, after injection molding, ZnS—SiO ₂ (80:20 mol%) is attached to the sufficiently cooled surface of the disk substrate 11 using the sputtering apparatus 100 to form the first dielectric layer 12 having a thickness of 50 nm. did. Incidentally, the film thickness relative values of the first dielectric layer 12, as shown by the curve L _A, thickness relative value near a position corresponding to the circle of radius 58mm was about 1.08.

Next, Bi ₂₀₃ -GeO ₂ (2: 1 mol%) was attached to the surface of the disk substrate 11 on which the first dielectric layer 12 was formed using the sputtering apparatus 100 to form the recording layer 13 having a thickness of 15 nm. .

Next, ZnS—SiO ₂ (80:20 mol%) was attached to the surface of the disk substrate 11 on which the recording layer 13 was formed using the sputtering apparatus 100 to form a second dielectric layer 14 having a thickness of 16 nm. .

Next, Si ₃ N ₄ was deposited as an intermediate layer using the sputtering apparatus 100 to form a layer having a thickness of 4 nm.

  Next, Ag—Nd—Bi (97.0: 2.5: 0.5 at%) is attached to the surface of the disk substrate 11 on which the intermediate layer is formed by using the sputtering apparatus 100, and the reflection with a thickness of 80 nm is performed. Layer 15 was formed.

  Next, an ultraviolet curable material was spin coated on the surface of the disk substrate 11 on which the reflective layer 15 was formed, and the overcoat layer 16 was formed by curing the material.

Next, a dummy substrate 18 having a thickness of 0.6 mm was bonded to the surface of the disc substrate 11 on which the overcoat layer 16 was formed, thereby manufacturing the optical disc 10 having a thickness of about 1.2 mm.
<< Comparative Example 1 >>
The first dielectric layer 12 of the optical disk in Example 1 was formed on the disk substrate 11 using the sputtering apparatus 100 in which the shielding member 50A was not installed.
<< Comparative Example 2 >>
The first dielectric layer 12 of the optical disk in Example 2 was formed on the disk substrate 11 using the sputtering apparatus 100 in which the shielding member 50A was not installed.

  Based on the standard of HD DVD-R using the optical disk evaluation apparatus (ODU-1000 manufactured by Pulstec Industrial Co., Ltd.) with respect to the optical disks according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2. Information was recorded under the conditions, and the optimum recording power of each optical disk was evaluated. The optimum recording power is a recording power when PRSNER (Partial Response signal to noise) is maximized. For example, as shown in FIG. 8, when the recording power changes, the PRSNR changes along the upwardly convex curve shown in FIG. The optimum recording power refers to the recording power corresponding to the vertex of the curve in FIG.

  FIG. 9 is a diagram showing a relative value of the optimum recording power at a radial position with the center of the disk substrate 11 as a reference. The relative value of the optimum recording power is a value normalized with the optimum recording power at the inner periphery of the recording area 10a as 1. Curves ex1 to ex4 in the figure show the relative values of the optimum recording powers of the optical discs according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2.

  As can be seen from FIG. 9, in the optical discs according to Example 1 and Example 2, the relative value of the optimum recording power was in the range of 0.95 to 1.05, and the fluctuation of the relative value of the optimum recording power was small. . On the other hand, in the optical disks according to Comparative Example 1 and Comparative Example 2, the relative value of the optimum recording power was in the range of 1.00 to 1.15 or more, and the fluctuation of the relative value of the optimum recording power was large. The reason will be described below.

  The composition of the recording layer formed on the disk substrate generally depends on conditions such as the state of the sputter target, the easiness of sputtering of elements contained in the sputter target, the input power during film formation, and the atmosphere during film formation. . For this reason, even if a recording layer having a uniform film thickness is formed in the recording area 10a, the properties of the recording layer are unlikely to be uniform. Specifically, the oxygen deficiency state is not uniform throughout the recording layer, and the recording characteristics are greatly different between the inner peripheral portion and the outer edge portion of the recording layer.

  For example, in FIG. 10, the relative value of the absorptance with respect to laser light (wavelength 405 nm), which changes according to the position from the center of the disk substrate on the recording layer, is indicated by a one-dot chain line, and the relative thickness value of the recording layer. Is shown as a solid line. The relative value of the absorptance is a relative value when the absorptance at the position on the recording layer closest to the center of the disk substrate 11 is 1. As shown in FIG. 10, the relative value of the film thickness is almost 1 at any position in the radial direction of the recording layer, whereas the relative value of the absorptance decreases as the distance from the center of the disk substrate 11 increases. Yes. This is because, while the recording layer has a constant film thickness, when recording information by irradiating the recording layer with laser light, the laser light power is reduced at the center and toward the outer edge. This means that it is necessary to increase the power of the laser beam.

  With this as one factor, in the optical discs of Comparative Example 1 and Comparative Example 2 as shown in FIG. 10, the absorption rate of the recording layer decreases from the inner peripheral part to the outer peripheral part, and as a result, the curve of FIG. As indicated by ex3 and the curve ex4, the maximum recording power rapidly increases at the outer peripheral portion of the recording layer.

  In order to make the recording characteristics of the optical disc uniform, it is conceivable to increase the thickness of the recording layer at a portion having a low absorptance. However, the recording layer and the first dielectric layer formed on the recording layer are overlapped. Considering the interaction between the body layer and the second dielectric layer, the recording characteristics of the optical disk can also be made uniform by improving the sensitivity of the recording layer at a low absorption rate.

Figure 11 is a graph showing changes in recording sensitivity (mW) with respect to the film thickness variation ratio, the straight line L ₁₂ represents the change in recording sensitivity of the first dielectric layer, the straight line L ₁₃ is the change in recording sensitivity of the recording layer A straight line L ₁₄ indicates a change in recording sensitivity of the second dielectric layer. The composition of the recording layer and the first and second dielectric layers in FIG. 11 is the same as that of the recording layer 13 and the first and second dielectric layers 12 and 14 in the optical disc 10.

As shown in FIG. 11, the change amount of the recording sensitivity to linear L ₁₂ thickness variation rate of the first dielectric layer shown is the recording layer and the second dielectric layer represented by the straight line L ₁₃ and the straight line L ₁₄ It is larger than the amount of change in recording sensitivity with respect to the film thickness fluctuation rate. Therefore, in order to adjust the optimum recording power according to the position of the recording layer so as to be constant regardless of the incident position of the laser beam, the film thickness distribution of the recording layer itself is adjusted and the laser beam of the optical disk is adjusted. It can be said that it is more effective to adjust the recording sensitivity to the laser beam of the optical disc by adjusting the film thickness distribution of the first dielectric layer than to adjust the absorptance with respect to.

  In the optical disc 10 according to this embodiment, the recording layer 13 includes a dye material, for example, Bi oxide, and an oxide of at least one element selected from B, Cu, Fe, Ge, and Zn. The relative value of the absorptance with respect to the laser beam in the layer 13 is as shown by a one-dot chain line in FIG. 10, and the first dielectric layer 12 is formed using the sputtering apparatus 100 so as to have a desired film thickness distribution. Thus, the recording sensitivity of the laser beam in the optical disc 10 can be made constant throughout the recording area 10a.

  Specifically, as shown by the curves ex1 and ex2 in FIG. 9, in the optical discs according to the first and second embodiments, the film of the first dielectric layer at the portion where the film thickness of the recording layer is small. By increasing the thickness, the relative value of the optimum recording power could be converged in the range of 0.95 to 1.05. From this result, it can be seen that the optimum recording power is substantially constant over the entire recording area 10a.

  As described above, in the first embodiment, the recording includes a Bi oxide and an oxide of at least one element selected from B, Cu, Fe, Ge, and Zn. On one side of the layer 13, the first dielectric layer 12 is formed with a film thickness distribution such that the outer edge of the recording area 10a is thick. Therefore, the recording sensitivity to the laser beam in the recording area 10a of the optical disc 10 is made uniform, that is, the recording characteristics of the optical disc are made uniform.

  When a circle C having a radius r centered on the center of the disk substrate 11 is defined on the recording area 10a, the circumference length of the circle C is A (r), and the shielding member is included in the circumference of the circle C. If the length of the circumference shielded by B is r (r) and the wraparound coefficient from the sputter target 25 is k, the shielding member is defined by the shielding rate defined by k · (B (r) / A (r)). A 50A shape can be defined.

When the value of r changes in the range from R4 to R1 in FIG. 6, if the shielding rate is constant, a wraparound portion where particles wrap around the shielding member such as the gap GA of the shielding member 50A is formed. However, when the shielding rate changes, a wraparound portion where the particles wrap around the shielding member is formed. Therefore, the shielding factor (R4 ≦ r ≦ R1) represented by k · (B (r) / A (r)) is set according to the film thickness distribution required for the thin film formed on the disk substrate 11. By deciding, the shape of the shielding member for forming a desired film thickness can be defined.
<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is used for the same or equivalent component as 1st Embodiment mentioned above, The description shall be abbreviate | omitted or simplified.

  FIG. 12 is a cross-sectional view of an optical disc 10 ′ according to the second embodiment. The optical disc 10 ′ is a BD-R that can record and reproduce information with a laser beam having a wavelength of about 400 nm. This optical disc 10 ′ is different from the optical disc 10 described above in the arrangement order of the layers formed on the surface of the disc substrate 11.

  As shown in FIG. 12, in the optical disc 10 ′, in the recording area 10a, a reflective layer 15, a second dielectric layer 14, a recording layer 13, and a first dielectric layer 12 are sequentially formed on the surface of the disc substrate 11. ing. Further, a cover layer 16 ′ substantially equivalent to the above-described overcoat layer 16 is formed on the surface of the disk substrate 11 on which the first dielectric layer 12 is formed, and the surface of the cover layer 16 ′ is covered with the cover layer 16 ′. The hard coat layer 19 having a higher hardness is formed by the same method as that for the overcoat layer 16.

  Also in the second embodiment, the reflective layer 15, the second dielectric layer 14, and the recording layer 13 are formed in a state where the shielding member 50A is removed from the sputtering apparatus 100 and the recording area 10a is completely exposed. Thereafter, the first dielectric layer 12 is formed in a state where a part of the recording area 10a is shielded by using the shielding member 50A. Hereinafter, a method for manufacturing the optical disc 10 'will be described.

  A disk substrate in which guide pellets having a thickness of 1.1 mm and a track pitch of 0.32 μm are formed on the surface by melting and injection molding polycarbonate pellets, which are raw materials of the disk substrate 11 of the optical disk 10 ′. 11 is formed.

  Next, after injection molding, AlTi (99: 1 wt%) is deposited on the sufficiently cooled surface of the disk substrate 11 using the sputtering apparatus 100 to form the reflective layer 15 having a thickness of 35 nm.

Next, ZnS—SiO ₂ (80:20 mol%) is attached to the surface of the disk substrate 11 on which the reflective layer 15 is formed by using the sputtering apparatus 100 to form the second dielectric layer 14 having a thickness of 10 nm. .

Next, Bi ₂₀₃ -B ₂₀₃ (2: 1 mol%) is attached to the surface of the disk substrate 11 on which the second dielectric layer 14 is formed by using the sputtering apparatus 100 to form the recording layer 13 having a thickness of 16 nm. To do.

Next, ZnS—SiO ₂ (80:20 mol%) is attached to the surface of the disk substrate 11 on which the recording layer 13 is formed by using the sputtering apparatus 100 to form the first dielectric layer 12 having a thickness of 10 nm. .

  Next, an ultraviolet curable material is spin-coated on the surface of the disk substrate 11 on which the first dielectric layer 12 is formed, and the cover layer 16 'is formed by curing the material.

  Next, an ultraviolet curable resin is similarly spin-coated on the surface of the disk substrate 11 on which the cover layer 16 ′ is formed to form a hard coat layer 19. Thereby, an optical disk 10 'having a thickness of about 1.2 mm can be obtained.

  As described above, in the first embodiment, the recording includes a Bi oxide and an oxide of at least one element selected from B, Cu, Fe, Ge, and Zn. On one side of the layer 13, the first dielectric layer 12 is formed with a film thickness distribution such that the outer edge of the recording area 10a is thick. Accordingly, it is possible to make the recording sensitivity to the laser beam in the recording area 10a formed on the optical disc 10 'uniform, that is, to make the recording characteristics of the optical disc uniform.

  As described above, the method for manufacturing an optical recording medium of the present invention is suitable for manufacturing an optical recording medium. The optical recording medium of the present invention is suitable for recording information.

1 is a plan view of an optical disc 10 according to a first embodiment of the present invention. 2 is a view showing a cross section of an optical disc 10. FIG. 1 is a diagram showing a schematic configuration of a sputtering apparatus 100. FIG. 4A is a perspective view showing the substrate holder 31 together with the disk substrate 11, and FIG. 4B is a view of the substrate holder 31 and the disk substrate 11 as viewed from the −Y side. FIG. 5A is a perspective view showing the annular member 35 and the vicinity thereof, and FIG. 5B is a side view showing the annular member 35 and the vicinity thereof. 5 is a diagram schematically showing a shielding member 50A and a recording area 10a formed on the disk substrate 11. FIG. It is a figure which shows the film thickness relative value of the thin film formed in the recording area 10a. It is a figure for demonstrating the definition of optimal recording power. It is a figure which shows the relative value of optimal recording power. It is a figure which shows the relative value of the absorptivity with respect to a laser beam, and the film thickness relative value of a recording layer. It is a figure which shows the change of the recording sensitivity with respect to a film thickness fluctuation rate. It is a figure which shows the optical disk 10 'concerning 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical disk, 10a ... Recording area | region, 11 ... Disk board | substrate, 11a ... Circular opening, 12 ... 1st dielectric material layer, 13 ... Recording layer, 14 ... 2nd dielectric material layer, 15 ... Reflective layer, 16 ... Overcoat layer , 16 '... cover layer, 17 ... adhesive layer, 18 ... dummy substrate, 19 ... hard coat layer, 20A ... vacuum chamber, 20B ... casing, 21 ... sputtering cathode, 23 ... backing plate, 25 ... sputter target, 30 ... rotation Unit: 31 ... Substrate holder, 32 ... Rotating mechanism, 33 ... Outer peripheral mask, 34 ... Inner peripheral mask, 35 ... Ring member, 40 ... Magnet, 100 ... Sputtering apparatus

Claims (11)

A method for producing an optical recording medium having a recording layer formed on a disk substrate and a protective layer formed on one side of the recording layer with a predetermined film thickness distribution,
An injection step of injecting particles emitted from a sputtering target including a material constituting the protective layer onto the rotating disk substrate;
A shielding step of shielding a part of the ejected particles based on the predetermined film thickness distribution. The method of manufacturing an optical recording medium according to claim 1, wherein the sputter target contains ZnS—SiO ₂ .   The method for manufacturing an optical recording medium according to claim 1, wherein the recording layer contains an oxide as a main component.   4. The optical recording medium according to claim 3, wherein the oxide includes Bi oxide and an oxide of at least one element selected from B, Cu, Fe, Ge, and Zn. Manufacturing method.   In the shielding step, based on the film thickness distribution of the protective layer formed on the disk substrate, a part of a film formation region on the surface of the disk substrate on which the protective layer is formed is ejected to the disk substrate. The method for producing an optical recording medium according to claim 1, wherein a shielding member that shields from light is used.   The shielding member has a different shielding rate for the film formation region at positions corresponding to at least two positions having different radial distances from the center of the disk substrate on the film formation region. The method for producing an optical recording medium according to claim 5.   The optical recording medium manufacturing method according to claim 6, wherein the shielding member has the smallest shielding rate at a position corresponding to a position farthest from a center of the disk substrate on the film formation region. Method.   The optical recording medium manufactured by the manufacturing method of the optical recording medium as described in any one of Claims 1-7. A recording layer on which laser light is incident from one side;
A film formed on one side of the recording layer and having a film thickness at a position 40 mm away from the center of the disk substrate as 1 and a distance between a position 50 mm away from the center of the disk substrate and a position 58 mm away The optical recording medium according to claim 8, further comprising: a protective layer having a thickness of 1 or more. A recording layer on which laser light is incident from one side;
Formed on one side of the recording layer and assuming a film thickness of 40 mm from the center of the disk substrate as 1, the film thickness at the position closest to the center of the disk substrate and the farthest from the center of the disk substrate The optical recording medium according to claim 8, further comprising: a protective layer having a difference in film thickness at a different position of 0.08 or more. A recording layer on which laser light is incident from the one side;
The optical recording medium according to claim 8, further comprising: a protective layer formed on one side of the recording layer and having a film thickness that increases from a center portion to an outer edge portion of the disk substrate.

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