JP2006179140A - Master disk of optical disk, method of manufacturing the same, and method of manufacturing optical disk stamper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a master disk of an optical disk capable of improving the adhesion between a resist material to be patterned and a master disk or an underlayer provided on the master disk, and to provide a method of manufacturing the master disk and a method of manufacturing an optical disk stamper. <P>SOLUTION: The adhesion of a patterned negative type resist material and the master disk 1 or the underlayer 2 can be secured by inserting an intermediate layer 3 formed of a low sensitive positive type resist material between a resist layer 4 and the master disk 1 or between the resist layer 4 and the underlayer 2, and thereby preventing stress being applied to the interface between the resist material and the master disk 1 or between the resist material and the underlayer 2 at the time of exposure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc master, a manufacturing method thereof, and a manufacturing method of an optical disc stamper.

  Optical discs used as information recording media today are proposed in various formats such as MD (Mini Disc), MO (Magneto Optical), DVD (Digital Versatile Disc), Blu-ray Disc (registered trademark), etc. Has been. An optical disk substrate used in any format is generally manufactured by injection molding of a resin material, and the price of the optical disk is reduced.

  In the injection molding of an optical disk substrate, in order to provide the optical disk with patterns such as grooves and pits, a stamper as an optical recording medium manufacturing master for transferring those patterns is disposed in the cavity of the injection molding apparatus.

  FIG. 11 is a schematic diagram showing an outline of a stamper manufacturing process for molding an optical disk substrate. With reference to FIG. 11, an outline of a stamper manufacturing method will be described.

  First, a very thin photoresist (photosensitive agent) 102 is applied onto the glass master 101 by spin coating or the like, and exposure is performed by the laser 103 of the cutting apparatus while rotating the glass master 101. A latent image having a pattern corresponding to the groove or pit is formed on the photoresist film by exposure.

  Thereafter, the developer 104 is dropped on the rotating glass master 101 and subjected to a development process, whereby an uneven resist pattern corresponding to the groove or pit of the optical disk is formed on the glass master 101.

  Next, a stamper 106 is obtained by depositing a metal 105 such as nickel on the glass master 101 by plating, peeling it, and performing trimming. The stamper 106 is disposed in the cavity of the injection molding apparatus, and a resin is injected into the cavity, whereby a disk substrate is manufactured.

  Conventionally, a novolac resin-based photoresist has been used as a photosensitive agent applied on the glass master 101. This inorganic resist material is a so-called positive resist material. That is, the exposed part is easily selectively dissolved in the developer, and the unexposed resist remains on the glass master after development. A stamper obtained by plating the glass master or the substrate is formed with a pattern in which the unevenness is reversed from the resist on the glass master.

  The shortest pit length that can be formed by using the above photosensitive agent is the wavelength λ of the exposure light source (laser) to be used and the numerical aperture NA of the objective lens for converging the luminous flux emitted from the light source to the photosensitive agent. It is determined by the following formula.

  P = K × λ / NA

  In the above equation, the proportionality constant K is a numerical value determined by the combination of the laser and the photoresist to be used, and is about 0.5 to 0.8. That is, in order to form a finer pattern corresponding to the higher recording density of the optical disc, it is necessary to shorten the wavelength of the light source and increase the NA of the objective lens.

  As for the shortening of the wavelength of the light source, an ultraviolet laser, electron beam exposure, or the like has been studied, but there are problems in comparison with the conventional cutting apparatus in terms of complexity and stability of the apparatus. NA is 1 or less by definition, and it is around 0.9 even with a commonly used objective lens. The shortest pit length (spot diameter) is 0.87 × 413 / 0.9 when K is 0.87, the laser wavelength used is 413 nm for the exposure of the DVD stamper, and NA is 0.9. = About 399 nm.

  The specification of the existing DVD has an information capacity of 4.7 GB on one side of an optical disk having a diameter of 12 cm, a minimum pit length of 400 nm, and a track pitch of 740 nm. Therefore, there is no problem in producing a DVD optical disk.

  However, in the case of a high-density optical disk with a single side of 25 GB, the shortest pit length is required to be about 170 nm. When K = 0.87 and NA = 0.95, λ = 185.6 nm. However, such a short wavelength laser is very special at present, and there is a problem that the cost of the system of the laser cutting apparatus is significantly increased.

  On the other hand, an inorganic resist material made of an incomplete oxide of a transition metal disclosed in Patent Document 1 below can expose a pattern smaller than the spot diameter by thermal recording characteristics even by exposure with a visible laser of about 405 nm. It is noted that the technology is useful as a mastering technology for optical discs corresponding to higher recording densities of Blu-ray Disks or higher.

JP 2003-315988 A

  The incomplete oxide of the transition metal here is a compound shifted in a direction in which the oxygen content is less than the stoichiometric composition corresponding to the valence that the transition metal can take, that is, in the incomplete oxide of the transition metal. It is a compound whose oxygen content is smaller than the oxygen content of the stoichiometric composition according to the valence that the transition metal can take.

  FIG. 12 is a schematic diagram of a Blu-ray Disc groove. As shown in FIG. 12, the left side is the disc inner peripheral side, and the right side is the disc outer peripheral side. On the innermost side, there is a BCA (Burst Cutting Area) area 111, and the pits in the PIC (Permanent Information & Control Data) area 112 and the grooves in the data recording area 113 are wobble grooves formed to meander. FIG. 12 is a schematic diagram, and the number of tracks does not indicate the actual number.

  A groove in an inner peripheral BCA (Burst Cutting Area) region 111 is a groove having a track pitch Tp1 of 2000 nm. The groove in the PIC area 112 is a rectangular wobble groove with a track pitch Tp2 of 350 nm. The groove in the PIC area 112 and the data recording area 113 is a wobble groove formed by a superposition signal of an MSK (Minimum Shift Keying) signal having a track pitch Tp3 of 320 nm and an STW (Saw Tooth Wobble) signal.

  Conventionally, a Blu-ray Disk disk substrate is manufactured by a method similar to the method described with reference to FIG. FIG. 13 is a schematic diagram illustrating a stamper manufacturing process necessary for manufacturing a disk substrate. Using a cutting device, a latent image of a desired groove of BCA 111 and PIC 112 and data recording area 113 is formed on resist 122 on glass master 121 by laser light. Since it is a positive resist material, the glass master is subjected to development processing, the exposed portion of the resist 122 is dissolved and developed, and a resist glass master patterned to have a recess corresponding to the groove is obtained. be able to.

  Next, a conductive film layer made of a nickel film is formed on the concave groove pattern of the resist glass master disk by electroless plating, etc., and the glass master disk on which the conductive film layer is formed is attached to an electroforming apparatus, and conductive by electroplating. A nickel plating layer is formed on the chemical film layer, and a convex groove pattern stamper (master stamper) 123 is produced.

  In the Blu-ray Disk, the wobbled groove is arranged closer to the optical pickup (reading surface). That is, it is necessary to obtain a good recording / reproducing characteristic that the groove has a convex shape on the substrate. However, as shown in FIG. 13, the stamper (master stamper 123) obtained by the plating process from the glass master 121 has the irregularities reversed, so that the wobbled groove becomes concave with respect to the reading surface. .

  Therefore, in order to reverse the unevenness and make a pattern of a desired shape, a stamper (mother stamper 124) in which the unevenness is inverted again by the plating process is produced from the master stamper 123, and injection molding is performed using the mother stamper 124. A disk substrate 125 having a groove Gv protruding on the side close to the reading surface is obtained.

  FIG. 14 is a schematic diagram of a Blu-ray Disc manufactured using a positive photoresist and having a groove protruding toward the side close to the optical pickup (reading surface). As shown in FIG. 14, a reflective layer, a second dielectric layer, a recording layer, and a first dielectric layer are formed on the signal forming surface (convex groove pattern) of the disk substrate 125, and the recording layer is formed on the recording layer. A cover layer 123 of 0.1 mm is formed. Through the above steps, a high-density phase change optical disk such as Blu-ray is completed.

  As described above, by producing the mother stamper 124 that is a replica stamper of the master stamper 123, the concave / convex pattern of the groove can be reversed, and the side closer to the optical pickup 127 (reading surface) as shown in FIG. Grooves Gv protruding in the shape can be formed. With this technique, the groove reproduction characteristic and the wobble characteristic can be improved.

  Unlike the Blu-ray Disk, the DVD format reads the concavo-convex pattern from the disk substrate side on which the concavo-convex pattern is not formed. Therefore, the master stamper 123 is used, or the mother stamper 124 is manufactured from the master stamper 123, and the sun stamper manufactured from the mother stamper 124 is used for injection molding.

  Here, it is difficult to manufacture the mother stamper 124 to which the pattern formed on the master stamper 123 is accurately transferred, and manufacturing the mother stamper 124 increases the number of processes and makes the disk manufacturing process complicated. Become a problem.

  Therefore, by performing mastering using a negative inorganic resist material, the manufacturing process of the mother stamper 124 can be simplified.

  FIG. 15 is a photograph showing the state of the exposed portion and the underlayer after laser exposure. In the case of a negative inorganic resist material, the exposed portion 133 exposed with a laser remains after development. As shown in FIG. 15, in the exposure unit 133, distortion occurs between the resist material 131 and the base layer 132 made of amorphous silicon as a heat storage layer due to volume expansion due to phase change. As a result, the adhesion between the resist material 131 and the base layer 132 is reduced.

  When the adhesion between the resist material 131 and the underlayer 132 is lowered, when the stamper is manufactured by electroforming, the resist material 131 may be peeled off from the optical disk master when the nickel stamper obtained is peeled off from the optical disk master. Arise.

  In order to suppress such peeling of the resist material, conventionally, an oxide film having a relatively high electrical conductivity is formed on an optical disk master, and then electroforming is performed to make the release property of the nickel stamper relatively Therefore, the resist material is prevented from being peeled off. However, there are cases where the resist material is peeled off, and the stamper yield is low.

  Conventional optical disc masters using a negative inorganic resist material have a problem in that the adhesion between the resist material and the master or a base layer provided on the master is reduced.

  Accordingly, an object of the present invention is to provide an optical disc master, a method of manufacturing the same, and a method of manufacturing an optical disc stamper, which can improve the adhesion between the resist material to be patterned and the master or a base layer provided on the master.

In order to solve the above-described problem, the first aspect of the present invention is:
An optical disc master having a negative resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal formed and patterned on a master or an underlayer formed on the master,
An optical disc master, wherein an intermediate layer is formed between the resist material and the master or between the resist material and the base layer, and an intermediate layer that does not change in phase with an exposure power that can be recorded on the resist material.

The second aspect of the present invention is:
A method for producing an optical disc master having a negative resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal film-formed and patterned on a master or an underlayer formed on the master,
A step of forming an intermediate layer that does not change in phase with an exposure power that can be recorded on a resist material on a master or an underlayer formed on the master, and
Forming a resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal on the intermediate layer;
An exposure step of irradiating a film made of a resist material with a laser beam to form a latent image;
And developing a resist material to form a concavo-convex shape corresponding to the latent image on the master or an underlayer formed on the master.

The third aspect of the present invention is:
Manufacture of an optical disc stamper for obtaining an optical disc stamper from an optical disc master having a negative resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal formed and patterned on the master or an underlayer formed on the master A method,
An optical disc stamper manufacturing method comprising: obtaining an optical disc stamper from an optical disc master on which an intermediate layer that does not change in phase with an exposure power that can be recorded on the resist material is formed between the resist material and the master disc or between the resist material and the underlying layer.

  According to the present invention, the adhesion between the patterned resist material and the master or the base layer provided on the master can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1A shows a resist master. As shown in FIG. 1A, the resist master is formed by sequentially stacking a master 1, an underlayer 2, an intermediate layer 3, and a resist layer 4.

  As the master 1, for example, a silicon wafer, plastic such as polycarbonate, glass, or the like is used.

  When a master wafer 1 having a high thermal conductivity such as a silicon wafer made of single crystal silicon (hereinafter, appropriately referred to as a silicon substrate) is used, even if a laser focused at the time of exposure of the resist layer 4 is irradiated. Since the diffusion of the amount of heat given to the resist layer 4 increases, exposure cannot be performed. Therefore, the base layer 2 made of amorphous silicon is inserted between the master 1 and the intermediate layer 3 as a heat storage layer. The diffusion of heat is suppressed by the amorphous silicon, and an exposure pattern can be formed on the formed resist layer 4.

  When the master 1 having a low thermal conductivity such as glass is used, amorphous silicon as the base layer 2 is not required. This is because if the master 1 is made of glass and amorphous silicon (underlying layer 2) is inserted between the master 1 and the intermediate layer 3, the heat is excessively confined and a fine pattern cannot be formed.

As the intermediate layer 3, a low-sensitivity positive resist material is used. By using a low-sensitivity positive resist material for the intermediate layer 3, the adhesion between the resist material and the underlayer 2 is improved. Specifically, an amorphous inorganic material containing an incomplete oxide of a transition metal, particularly an amorphous inorganic material containing WO _x , MoO _x , W, Mo, or CrOx is used.

  As the resist layer 4, a negative resist material is used. Specifically, an amorphous inorganic material containing an incomplete oxide of a transition metal, particularly an amorphous inorganic material containing W or Mo is used. Examples of the method for forming the resist layer 4 include a sputtering method and a vapor deposition method.

  FIG. 1B is a partially enlarged cross-sectional view showing a resist master after exposure. In FIG. 1B, reference numeral 5 indicates an exposed portion irradiated with a laser. A latent image of a concavo-convex resist pattern is formed by the exposure unit 5.

  FIG. 1C is a partially enlarged sectional view showing the resist master after development. As shown in FIG. 1C, after development, the exposed portion 5 irradiated with the laser remains, and an optical disc master having a concavo-convex resist pattern corresponding to the latent image is produced.

  FIG. 2 is a graph showing the relationship between the amount of oxygen introduced, the oxygen content in the resist film, and the shape of the resist. When producing a resist film on a substrate by reactive sputtering using a mixed gas of argon and oxygen, an oxygen flow ratio is appropriately selected. The sensitivity of the inorganic resist material varies depending on the oxygen content. Therefore, it functions as a positive resist or negative resist by selecting the oxygen content in the film. Specifically, as shown in FIG. 2, the oxygen content in the film is 72 at. % To 74 at. When it is%, it functions as a negative resist. The oxygen content in the film is 53 at. % To 65 at. %, It functions as a positive resist.

  FIG. 3 is a graph showing changes in the width of the groove pattern. The graph shown in FIG. 3 takes the exposure power (mW) on the horizontal axis and the groove width (nm) on the vertical axis.

  The graph shown in FIG. 3 shows a change in the width of the groove pattern when the resist material is exposed to light with a laser having a wavelength of 405 nm and then etched with a developer. The curve of reference symbol a has an oxygen content of 72 at. It is the curve regarding the negative resist material of the incomplete oxide of a transition metal made into%. The curve with the reference sign b shows an oxygen content of 65 at. It is the curve regarding the positive type resist material of the incomplete oxide of a transition metal made into%. The curve with the reference sign c shows an oxygen content of 63 at. It is the curve regarding the positive type resist material of the incomplete oxide of a transition metal made into%. The curve with the reference sign d shows an oxygen content of 53 at. It is the curve regarding the positive type resist material of the incomplete oxide of a transition metal made into%.

  For example, the desired groove width of the Blu-ray Disk is about 160 nm. When trying to obtain a groove pattern of about 160 nm, it can be confirmed from the graph shown in FIG. 2 that a resist material having a higher oxygen content has higher sensitivity and a 160 nm groove pattern can be obtained with a low exposure power.

  Specifically, the oxygen content is 53 at. % Positive resist is not exposed to the optimum exposure power of the negative resist that can provide the desired Blu-ray Disk groove pattern (160 nm groove pattern) as shown by curve d, and no pattern is formed. Can be confirmed from the graph shown in FIG.

  Therefore, the intermediate layer 3 made of a low-sensitivity positive resist material is inserted between the resist layer 4 and the master disk 1 or between the resist layer 4 and the underlayer 2 so that the resist material and the master disk 1 or the resist material and the lower layer are exposed at the time of exposure. It is possible to prevent stress from being applied to the interface between the base layers 2 and to ensure adhesion between the master 1 or the base layer 2 and the patterned negative resist material.

  Hereinafter, a method for manufacturing an optical disc master according to an embodiment of the present invention will be described.

<Pretreatment of intermediate layer and resist layer production>
When the base layer 2 is provided, the base layer 2 existing between the master 1 and the intermediate layer 3 is prepared as a process before forming the intermediate layer 3 and the resist layer 4. In addition, when using the thing with small heat conductivity as the original recording 1, the base layer 2 is not required.

<Intermediate layer and resist layer manufacturing process>
FIG. 4 is a schematic diagram illustrating an example of a sputtering apparatus for forming a resist material. Using a binary sputtering apparatus shown in FIG. 4, for example, a resist material made of an incomplete oxide of a transition metal is formed by sputtering on a silicon substrate 31 whose surface is sufficiently smoothed. In FIG. 4, reference numeral 30 indicates a pallet. A tungsten (W) target 32 is attached to the cathode connected to one high frequency power supply 34, and a molybdenum (Mo) target 33 is attached to the cathode connected to the other high frequency power supply 35. Reference numerals 36 and 37 denote matching boxes, respectively.

  The silicon substrate 31 is attached to the substrate holder and rotates on the substrate holder. The substrate holder is structured to rotate (revolve) in the sputtering apparatus, and the alloy film can be deposited by revolving the silicon substrate 31 with the tungsten W and molybdenum Mo cathodes discharged. it can. Further, the mixing ratio can be controlled by changing the input power.

At this time, by introducing argon (Ar) and oxygen (O ₂ ) into the deposition gas, an inorganic resist material made of oxides of tungsten (W) and molybdenum (Mo) can be obtained. In addition, the degree of oxidation of the incomplete oxide of the transition metal can be controlled by changing the oxygen concentration in the deposition gas. By changing the oxygen concentration, a positive resist material as an intermediate layer and a negative resist material as a resist layer are formed.

<Resist layer exposure process>
FIG. 5 is a schematic diagram showing an example of a cutting apparatus for exposing a resist layer. The resist master 40 on which the resist layer 41 is formed on the silicon substrate 31 is set on the turntable 42 so that the resist layer 41 is on the upper side.

  The laser cutting apparatus shown in FIG. 5 is for exposing a resist layer 41 formed on a resist master 40 to form a resist pattern latent image on the resist layer 41. When forming a latent image on the resist layer 41, the resist master 40 is attached to a rotation driving device 42 provided on the moving optical table 50. Then, when exposing the resist layer 41, the resist layer 41 is rotationally driven by the rotary drive device 42 and translated by the moving optical table 50 so that the entire surface of the resist layer 41 is exposed in a desired pattern.

  The laser cutting device includes a light source 44 that emits laser light, a rotation drive device 42, a spindle servo 43, a drive driver 48, a position sensor 60, a laser scale 61, an air slider 62, and a feed servo 63. And a beam expander 52.

  The laser light emitted from the light source 44 is reflected by the mirror M1 and the mirror M2 and guided horizontally and in parallel on the moving optical table 50.

  As the light source 44, any light source that emits laser light having a short wavelength can be used. Specifically, for example, a Kr laser that emits laser light having a wavelength λ of 266 nm is suitable.

  The laser beam reflected by the mirror M2 and guided horizontally onto the moving optical table 50 is optically deflected by a wedge prism 46 and an acousto optical deflector (AOD) 47 and then subjected to a beam expander ( BEX) 52.

The acousto-optic deflector 47 is for applying an optical deflection to the laser beam so as to correspond to the wobble of the groove. That is, the laser light is incident on the acousto-optic deflector 47 via the wedge prism 46, and the acousto-optic deflector 47 performs optical deflection so as to correspond to a desired exposure pattern. Here, as the acoustooptic element used in the acoustooptic deflector 47, for example, an acoustooptic element made of tellurium oxide (TeO ₂ ) is suitable. The laser beam optically deflected by the acousto-optic deflector 47 is emitted through the wedge prism 46.

  The wedge prism 46 allows laser light to be incident on the grating surface of the acoustooptic device of the acoustooptic deflector 47 so that the Bragg condition is satisfied. This is for deflecting and changing the horizontal height of the beam.

  Here, a driving driver 48 for driving is connected to the acousto-optic deflector 47. A high frequency signal from a voltage controlled oscillator (VCO) 51 is supplied to the driving driver 48 together with a DC voltage. A control signal is supplied to the voltage controlled oscillator 51. Then, the acousto-optic deflector 47 is driven by the driving driver 48, whereby the optical deflection is applied to the laser light.

  Specifically, the control signal supplied to the voltage controlled oscillator 51 is, for example, a zero-level direct current (DC) signal when forming a groove in the BCA region, and bypass when forming a rectangular wobble groove in the PIC region. It is a rectangular signal of phase modulation. In the case of forming a wobble groove in the data recording area, it is a superimposed signal of an MSK signal of 956.5 kHz and an STW signal of 1923 kHz.

  The laser light optically deflected by the wedge prism 46 and the acoustooptic deflector 47 is incident on a beam expander (BEX) 52. The beam expander (BEX) 52 can convert the beam diameter.

  The laser light is made a predetermined beam diameter by a beam expander (BEX) 52, reflected by a mirror M3, guided to an objective lens 49, and condensed on the resist layer 41 by the objective lens 49.

  The resist layer 41 is exposed with laser light, and a latent image corresponding to the resist pattern is formed on the resist layer 41. At this time, the resist master 40 to which the resist layer 41 is applied is rotated by the rotation driving device 42 and is moved by the moving optical table 50 so that the entire surface of the resist layer 41 is exposed in a desired pattern. The laser beam is moved in the radial direction. As a result, a latent image corresponding to the irradiation locus of the laser light is formed over the entire surface of the resist layer 41. As an example, the rotational speed of the rotary drive device 42 is controlled so that the linear velocity in the longitudinal direction of the track is constant at 5.28 m / s.

  The moving optical table 50 is exposed at a feed pitch of 2000 nm in the BCA area, 350 nm in the PIC area, and 320 nm in the data recording area. In this laser cutting apparatus, the position of the moving optical table 50 is detected by the position sensor 60, and exposure is performed at a timing and a pitch corresponding to each area, so that the BCA area, the PIC area, and the data are as described above. The latent image of the groove pattern in the recording area can be exposed on the resist layer 41. Further, it is possible to change the feed pitch of the moving optical table 50 instantaneously by controlling the operations of the feed servo 63 and the air slider 62 with reference to the wavelength detected by the laser scale 61 (for example, 0.78 μm). Is done.

  The feed pitch is 2000 nm during the BCA region (radius r = 21.3 mm to 22.0 mm), and the feed pitch is gradually increased from 2000 nm to 350 nm during the track pitch transition region (radius r = 22.0 mm to 22.4 mm). To change. The feed pitch is 350 nm in the PIC region (radius r = 22.4 mm to 23.2 mm), and the feed pitch is gradually changed from 350 nm to 320 nm in the track pitch transition region (radius r = 23.2 mm). The data recording area (radius r = 23.2 mm to 58.5 mm) is formed at a feed pitch of 320 nm.

  Note that the objective lens 49 for condensing the laser beam on the resist layer 41 preferably has a large numerical aperture NA so that a finer groove pattern can be formed. An objective lens having a number NA of about 0.9 is suitable.

<Resist layer development process>
The development is performed, for example, by dropping a tetramethylammonium hydroxide solution while rotating the resist master 40 on which the latent image is formed. By developing the resist master 40 on which the latent image is formed, an optical disk master having a concavo-convex resist pattern corresponding to the latent image formed on the silicon substrate 31 is obtained.

As the developer, a liquid such as an acid or an alkali can be used. Specifically, examples of the alkaline solution include KOH, NaOH, or Na ₂ CO ₃ solution in addition to the tetramethylammonium solution. Examples of the acidic solution include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and the like.

  FIG. 6 is a view for explaining a stamper manufacturing process according to another embodiment of the present invention. As shown in FIG. 6, a master stamper 23 made of a nickel plating layer can be obtained from an optical disk master 26 in which an intermediate layer 25 is laminated on a silicon substrate 21 and a resist pattern made of a resist material 22 is formed.

  After the master stamper 23 is formed, the master stamper 23 can be used as a stamper for injection molding to produce a disk substrate 24 having a groove whose groove is convex with respect to the reading surface.

  In the DVD format, when a positive resist is used to read the groove from the disk substrate side, a mother stamper is produced from the master stamper 23, and the mother stamper is used as a stamper for injection molding. In this step, a mother stamper is not required as compared with the case where a positive resist is used, so that the stamper manufacturing process can be simplified.

  FIG. 7 is a photograph showing an atomic force microscope image of the first master stamper 23 produced from the optical disc master of the present invention. FIG. 8 is a photograph showing an atomic force microscope image of the second master stamper produced from the optical disc master of the present invention. A conventional optical disc master made of an organic resist material has low resist material rigidity and adhesion, and only one stamper can be produced from a single optical disc master.

  On the other hand, in the optical disc master of the present invention, since the adhesiveness of the resist is improved, even if a plurality of master stampers 23 are produced from the same optical disc master as shown in FIGS. The same stamper can be obtained without any collapse. That is, according to the present invention, a plurality of molding stampers can be obtained without producing a mother stamper, and the manufacturing cost of the optical disk can be reduced.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
In a sputtering chamber (not shown in FIG. 4), an amorphous silicon film having a thickness of 100 nm was formed as a base layer on a silicon substrate with an input power of 2.5 kW and a deposition argon gas pressure of 3.7 mTorr (0.49 Pa).

  Subsequently, as an intermediate layer, W (tungsten) and Mo (molybdenum) cathodes were respectively charged in a mixed gas of oxygen and oxygen introduced at a flow rate ratio of 10% (gas pressure 1.0 mTorr, 0.13 Pa). Electric discharge was performed at 1.0 kW and 0.19 kW, and a positive inorganic resist material made of tungsten and molybdenum oxide was formed to a thickness of 3 nm.

  Subsequently, as a resist layer, argon and oxygen having a flow rate ratio of 25% are introduced, and tungsten and molybdenum are discharged at input powers of 1.0 kW and 0.19 kW, respectively, to thereby form a negative inorganic resist made of tungsten and molybdenum oxide. The material was deposited to 25 nm.

<Example 2>
An amorphous silicon film having a thickness of 100 nm was formed as a base layer by the same method as in Example 1.

  Subsequently, as an intermediate layer, tungsten and molybdenum cathodes were introduced in a mixed gas of argon and oxygen introduced at a flow rate ratio of 10% (gas pressure 1.0 mTorr, 0.13 Pa). The positive inorganic resist material made of tungsten and molybdenum oxide was deposited to a thickness of 5 nm by discharging at .19 kW.

  Subsequently, as a resist layer, argon and oxygen having a flow rate ratio of 25% are introduced, and tungsten and molybdenum are discharged at input powers of 1.0 kW and 0.19 kW, respectively, to thereby form a negative inorganic resist made of tungsten and molybdenum oxide. The material was deposited to 25 nm.

<Example 3>
An amorphous silicon film having a thickness of 100 nm was formed as a base layer by the same method as in Example 1.

  Subsequently, as an intermediate layer, tungsten and molybdenum cathodes were introduced in a mixed gas of argon and oxygen introduced at a flow rate ratio of 10% (gas pressure 1.0 mTorr, 0.13 Pa). The positive inorganic resist material made of tungsten and molybdenum oxide was deposited to a thickness of 10 nm by discharging at .19 kW.

  Subsequently, as a resist layer, argon and oxygen having a flow rate ratio of 25% are introduced, and tungsten and molybdenum are discharged at input powers of 1.0 kW and 0.19 kW, respectively, to thereby form a negative inorganic resist made of tungsten and molybdenum oxide. The material was deposited to 25 nm.

<Comparative Example 1>
An amorphous silicon film having a thickness of 100 nm was formed as a base layer by the same method as in Example 1.

  Subsequently, as a resist layer, argon and oxygen having a flow rate ratio of 25% are introduced, and tungsten and molybdenum are discharged at input powers of 1.0 kW and 0.19 kW, respectively, to thereby form a negative inorganic resist made of tungsten and molybdenum oxide. The material was deposited to 25 nm.

  As described above, the obtained resist master was exposed and developed under the following conditions.

Exposure device: Cutting device (Fig. 5)
Light source: Semiconductor laser (wavelength 405 nm, Pw 3.2 mW)
Objective lens: NA = 0.90
Objective lens feed rate: 0.32 μm / revolution
Spindle: CLV (Constant Linear Velocity) method 2.0m / sec
Developer: Tetramethylammonium hydroxide solution.

  Under the above exposure conditions, the resist layer is exposed and developed with a DC groove pattern, and the resist pattern of the produced optical disc master (Examples 1 to 3 and Comparative Example 1) is measured by an atomic force microscope (AFM). Observed. FIG. 9 is a photograph showing resist patterns of the optical disc masters of Examples 1 to 3 and Comparative Example 1. As shown in FIG. 9, a resist pattern having a width of 160 nm is formed on the master.

  Subsequently, an oxygen content of about 5 nm on this optical disk master is 63 at. After forming a conductive film made of% positive resist by sputtering, a nickel film 280 μm as a master stamper was deposited by electroforming.

  After producing the master stamper, the master stamper was peeled off, and the resist pattern of the optical disc master after peeling off the master stamper was observed with an atomic force microscope.

  FIG. 10 is a photograph showing the resist pattern of Comparative Example 1. As shown in FIG. 10, in Comparative Example 1, a part of the resist was peeled off. From FIG. 10, it was found that in Comparative Example 1, the adhesion of the resist was weak, and when the master stamper was peeled off, a part of the resist pattern was peeled off together with the stamper. The peeled resist was adhered to the master stamper side, and it was found that the master stamper produced from Comparative Example 1 was not suitable for molding an optical disk substrate.

  In Examples 1 to 3, a resist pattern as shown in FIG. 9 could be observed. That is, it was found that in Examples 1 to 3, the resist pattern was not peeled off.

  From this result, it was found that in Examples 1 to 3, even when a plurality of master stampers were produced from the same optical disc master, pattern collapse was not observed, and similar stampers could be obtained.

  Note that when the thickness of the intermediate layer is increased, the sensitivity of the resist is greatly reduced, so that the thickness of the intermediate layer is effective up to 10 nm.

  The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention.

It is a partially expanded sectional view of the optical disk master of this invention. It is a graph which shows the relationship between the amount of oxygen introduction | transduction, the oxygen content in a resist film, and the behavior of a resist. It is the graph which showed the change of the width of a groove pattern. It is a basic diagram which shows the outline | summary of the stamper preparation process for optical disk substrate shaping | molding. It is an approximate line figure showing an example of a cutting device for exposing an inorganic resist layer. It is a figure for demonstrating the manufacturing process of the stamper of this invention. 2 is a photograph showing an atomic force microscope image of a first master stamper produced from an optical disc master of the present invention. 3 is a photograph showing an atomic force microscope image of a second master stamper produced from the optical disc master of the present invention. 3 is a photograph showing resist patterns of Examples 1 to 3 and Comparative Example 1. 6 is a photograph showing a resist pattern of Comparative Example 1. It is a basic diagram which shows the outline | summary of the stamper preparation process for optical disk substrate shaping | molding. It is a schematic diagram of the groove | channel of Blu-ray Disc. It is a basic diagram which shows the preparation process of the stamper required for preparation of a disk substrate. FIG. 6 is a schematic diagram of a Blu-ray Disc manufactured using a positive photoresist and having a groove protruding toward the side close to the optical pickup (reading surface). It is the photograph showing the state of the exposure part and base layer after laser exposure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Master 2 ... Underlayer 3 ... Intermediate layer 4 ... Resist layer 5 ... Exposure part 21 ... Silicon substrate 22 ... Resist layer 23 ... Master stamper 24 ...・ Disk substrate 25 ... Intermediate layer 26 ... Master optical disc

Claims (21)

An optical disc master having a negative resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal formed and patterned on a master or an underlayer formed on the master,
An optical disc master, wherein an intermediate layer that does not change in phase with an exposure power that can be recorded on the resist material is formed between the resist material and the master or between the resist material and the base layer. In claim 1,
The optical disc master, wherein the intermediate layer is made of an amorphous inorganic material containing an incomplete oxide of a transition metal. In claim 1,
The intermediate _layer, WO X, the optical disc master, characterized in that it consists of an amorphous inorganic material containing MoO _X, W, Mo or CrOx. In claim 1,
The optical disk master, wherein the resist material contains W or Mo. In claim 1,
The resist material has an oxygen content of 72 at. % To 74 at. An optical disc master characterized by being an oxide film made up of%. In claim 1,
The intermediate layer has an oxygen content of 53 at. % To 65 at. An optical disc master characterized by being an oxide film made up of%. In claim 1,
An optical disc master, wherein the intermediate layer has a thickness of 3 nm to 10 nm. A method for producing an optical disc master having a negative resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal film-formed and patterned on a master or an underlayer formed on the master,
Forming an intermediate layer that does not change in phase with an exposure power that can be recorded on the resist material, on the master or on the base layer formed on the master; and
Depositing the resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal on the intermediate layer;
An exposure step of irradiating the film made of the resist material with a laser beam to form a latent image;
And a step of developing the resist material to form a concavo-convex shape corresponding to the latent image on the master or an underlayer formed on the master. In claim 8,
The method for manufacturing an optical disc master, wherein the intermediate layer is made of an amorphous inorganic material containing an incomplete oxide of a transition metal. In claim 8,
The intermediate _{layer, WO X, MoO X, W} , a manufacturing method of the optical disc master, characterized in that it consists of an amorphous inorganic material containing Mo or CrOx. In claim 8,
The resist material contains W or Mo. A method of manufacturing an optical disc master. In claim 8,
The resist material has an oxygen content of 72 at. % To 74 at. %. A method of manufacturing an optical disc master, characterized in that the oxide film is defined as%. In claim 8,
The intermediate layer has an oxygen content of 53 at. % To 65 at. %. A method of manufacturing an optical disc master, characterized in that the oxide film is defined as%. In claim 8,
The method of manufacturing an optical disc master, wherein the intermediate layer has a thickness of 3 nm to 10 nm. Manufacture of an optical disc stamper for obtaining an optical disc stamper from an optical disc master having a negative resist material made of an amorphous inorganic material containing an incomplete oxide of a transition metal formed and patterned on the master or an underlayer formed on the master A method,
A method of manufacturing an optical disc stamper, comprising: obtaining an optical disc stamper from an optical disc master having an intermediate layer that does not change in phase with an exposure power that can be recorded on the resist material between the resist material and the master disc or between the resist material and the underlying layer. . In claim 15,
The method for manufacturing an optical disc stamper, wherein the intermediate layer is made of an amorphous inorganic material containing an incomplete oxide of a transition metal. . In claim 15,
The intermediate _{layer, WO X, MoO X, W} , a method of manufacturing an optical disc stamper characterized by comprising an amorphous inorganic material containing Mo or CrOx. In claim 15,
The method of manufacturing an optical disc stamper, wherein the resist material contains W or Mo. In claim 15,
The resist material has an oxygen content of 72 at. % To 74 at. A method for manufacturing an optical disc stamper, characterized by comprising: In claim 15,
The intermediate layer has an oxygen content of 53 at. % To 65 at. A method for manufacturing an optical disc stamper, characterized by comprising: In claim 15,
The method for manufacturing an optical disc stamper, wherein the intermediate layer has a thickness of 3 nm to 10 nm.