JPH02292028A - Stamper for optical disc - Google Patents

Abstract

PURPOSE:To obtain an optical disc stamper having a high mold releasing property and excellent durability by forming an inorganic thin film protecting layer with a high mold releasing property from radiation curing resin on a stamper surface. CONSTITUTION:On a photoresist film 3 with a prepit 1 and pregroup 2, one of nitride or carbide of Si, Al, Ti is sputtered for forming a protecting film 4. And, Ni layer 6 is formed by forming an Ni layers 5, furthermore, performing Ni plating thereon. And then, an anaerobic thermosetting adhesive agent 7 is applied on the surface of the Ni layer 6, and a reinforcement material 8 is stuck thereto, and the adhesive agent 7 is cured thereafter. The photoresist layer 3 and the protecting layer 4 are separated from each other, and the photoresist remained on the surface of the protecting layer 4 is removed then. After an acrylic protecting plate is stuck thereto through ultraviolet-setting resin, an optical disc is obtained by working it into a predetermined dimension. The stamper for an optical disc manufacture herein has an excellent mold releasing property, and may not be subjected to any stresses during the separation, and also has high superficial hardness and excellent durability against hardened substances of radiation curing resin as a replica material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stamper for optical disc recording media, and more particularly to an optical disc stamper that has a long life and does not deform even after multiple uses.

[Prior Art] Conventionally, as a stamper for an optical disc recording medium (hereinafter simply referred to as "optical disc"), for example, [Precision Machinery, Vol. 50, No. 12 J (1984, p. 1844,
Nobuhiro Funakoshi “Materials for optical discs and their processing methods”),
[As shown in National Technical Report, Vol. 29, No. 5 J (1983, p. 752, Yoshihiro Okino et al., "Master production of optical discs using lasers"),
It is known that the stamper surface is formed by plating with nickel (Ni) to have a thickness of approximately 300 μm. A radiation-curable resin is used as one of the materials for the optical disk replica, and when manufacturing the optical disk replica, this resin is peeled off from the stamper surface after hardening.

[Problems to be Solved by the Invention] In the above conventional technology, when an optical disk replica is peeled off from a stamper, the adhesion between the radiation-curable resin of the replica and the Ni surface of the stamper is large (releasability is low). Therefore, stress is applied to the Ni surface, and there is a possibility that blip pits (signals) and pregrooves (guide grooves) formed on the Ni surface are deformed. For this reason, the number of optical disk replicas that can be produced with one stamper is limited to about 300, resulting in problems such as a short stamper life and a decline in the quality of the replicas (playback noise characteristics, etc.). Therefore, an object of the present invention is to overcome the problems of the prior art described above, and to provide an optical disk replica with high mold releasability (mold releasability) from radiation-curable resin, excellent durability (long life, and high quality). An object of the present invention is to provide a stamper for optical discs (which can produce a large number of optical disc replicas).

[Means for Solving the Problems] In order to achieve the above object, the optical disc stamper of the present invention has a mold release material on its surface (the surface on which pre-pits and pre-grooves are formed) for radiation-curable resin as a replica material. Forms a thin inorganic protective layer made of a material with high peelability. This inorganic thin film protective layer is made of the following materials, which have extremely high releasability from radiation-curable resins compared to Ni: silicon, aluminum, and transition metals from Group IVa to Group VIa of the periodic table (T l
* W + MO + T a s...) Any one of nitrides or carbides is used.

Among the transition metals in Group IVa mentioned above, those in the early periods of the periodic table (light metal yt) have closer atomic radii to carbon and nitrogen, so they form a dense protective film and are preferred. Titanium (Ti) is particularly effective as a transition metal.

[Effect] The operation based on the above configuration will be explained.

By providing the inorganic thin film protective layer, when the replica is peeled off from the stamper, the peelability between the replica and the radiation-curable resin is high, so stress is prevented from being applied to the stamper surface and causing deformation. A long-life stamper that can produce a large number of optical disc replicas with a low reproduction noise level can be obtained.

The surface of the stamper is composed of a Ni layer having pre-pits and pre-grooves, and the inorganic thin film protective layer is made of silicon (Si), aluminum (AΩ), transition metals of groups rVa to VIa of the periodic table ( In particular, a nitride or carbide of any one of Ti) is used. It has been found that these protective layer materials have extremely low affinity with the radiation-curable resin compared to the Ni layer. For this reason, mold releasability is significantly improved compared to the case where the radiation-curable resin is brought into direct contact with the Ni layer. In addition to nitrides and carbides, we also experimented with oxides of the same metals as above as materials for the inorganic thin film protective layer, but the separation was about the same as that of the Ni stamper in which an oxide layer was formed by 02 plasma treatment on the Ni surface. It was a pattern. The reason why oxides have lower mold releasability than carbides and nitrides is that carbides have the smallest surface energy in the order of metals, oxides, nitrides, and carbides. This is because it is thought that the interaction at will decrease in this order, and the smaller the interaction, the better the mold releasability. In oxide systems, adsorbed water on the surface causes chemical adsorption as shown in (chemical absorption), and hydroxyl groups -OH are likely to be formed.

In addition, the method for manufacturing a standby is to first form a Ni vapor deposition layer, a plating layer, etc. on a photoresist film, then peel off the photoresist film and form an inorganic thin film protective layer on the surface of the Ni layer by sputtering or the like. One possible method is to first form an inorganic thin film protective layer on the photoresist film by sputtering or the like, then further form a Ni vapor deposited layer, a plating layer, etc., and then peel off the photoresist film. The latter method is more advantageous since the surface of the Ni layer is likely to become rough when forming the inorganic thin film protective layer. According to experiments, the noise level of an optical disk replica is also lower with a stamper using the latter method than with a stamper using the former method.

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

Dear Master, Figure 1 shows the manufacturing process of the stamper of this example and a cross-sectional view of the stamper. As shown in Figure (a), there are pre-pits (parts corresponding to the signal of the optical disk replica, the angle between the wall surface and the plate surface is approximately 50 to 60@) 1 and pre-grooves (parts corresponding to guide grooves). On the photoresist film 3 on which the wall surface has an angle of about 20° with the plate surface, one of Si, AM, and Ti, nitride, or carbide is sputtered. As a result, a protective layer 4 having a thickness of 10 to 100 ns* is formed.
In addition, in the figure, 9 is a glass substrate on which the photoresist film 3 is formed. First, a Ni layer 5 with a thickness of about 100 nm is formed by vapor deposition or the like, and then Ni plating is performed on the Ni layer 5 to form a Ni layer 6 with a thickness of about 300 μm. An anaerobic thermosetting adhesive 7 is applied to the surface of the Ni layer 6, a reinforcing material 8 with a thickness of about i0 mm is attached, and the adhesive 7 is cured by treatment at 50 to 60° C. for 12 hours or more. After curing, as shown in Figure (b)? Uni, photoresist/! 3 and protective N4 are mutually peeled off, and the photoresist remaining on the surface of protective layer 4 is ashed with 02 plasma (oxygen plasma is used to remove water and CO2).
(a treatment method that decomposes and removes it). An acrylic protective plate (not shown) is bonded to this using an ultraviolet curing resin, and then processed to a predetermined size to obtain an optical disc stamper. This acrylic protection plate is for protecting the stamper surface during the above-mentioned dimensional processing.

The optical disc stamper produced as described above is
Conventional direct Ni
Compared to stampers whose surfaces are in contact, it has superior mold releasability, receives almost no stress during peeling, and has a high surface hardness. Since it acts as a corrosion prevention layer for Ni, it has extremely excellent machinability. Furthermore, in this embodiment, the protective layer M4 is first formed by sputtering, and then the Ni layers 5 and 6 are formed, so that the Ni layer does not become rough as would be the case when the protective layer is formed later by sputtering. For reference, the adhesion (adhesive strength) of the above-mentioned radiation-curable resins to various members is in the following order. ■ Substrate subjected to primer treatment (pretreatment with adhesive strengthening agent, binder, etc.) (substrate of optical disk replica, not shown)〉■ Ni metal layer〉■ Nitride of Si, AQ, Ti,
carbide.

Lost solitary This embodiment will be explained with reference to FIG.

On the photoresist film 3 formed in the same manner as in Example 1,
A Ni layer 5 with a thickness of about 100 nm is formed by vapor deposition, and then Ni plating is performed to form a Ni layer 6 with a thickness of about 300 μm. An anaerobic thermosetting adhesive 7 is applied to the surface of the Ni layer 6, and a reinforcing material 8 with a thickness of approximately 10 ms is bonded to the Ni layer 6, followed by treatment at 50 to 60° C. for 12 hours or more to harden the adhesive 7. After curing, the photoresist layer 3 and the Ni layer 5 are peeled off from each other, and the photoresist remaining on the surface of the Ni layer 5 is removed by ashes using 02 plasma. An acrylic protective plate (both not shown) is pasted on this surface using ultraviolet curing resin. This acrylic protection plate is used to protect the surface of the Ni layer from being scratched by a cutting tool or the like from being attached to or damaging the surface during the next dimensional processing. After processing to a predetermined size, the acrylic protective plate and the ultraviolet-cured resin are peeled off from the surface of the Ni layer 5, and the acrylic protective plate and the ultraviolet-cured resin are peeled off from the surface of the Ni layer 5. A protective film 4 with a thickness of 10 to 100 nm is formed by sputtering a nitride or carbide of any one of Si, AQ, metals from groups IVa to VIa of the periodic table, especially Ti, and a stamper for an optical disc is obtained. . In this case, depending on the thickness of the protective film 4, the shape (
For example, the inclination of the wall surface) and dimensions (for example, radius) change (for example, when viewed with a stamper, the width of the protruding parts corresponding to the pre-bits and pre-grooves increases by the amount that this protective film is attached). ), prepits and bullet loops are formed in the photoresist film 3 in advance so as to take into account this change and correct it (that is, to make the width a little narrower).

In this example, as in Example 1, it is possible to obtain an optical disk stamper which has excellent mold releasability, high surface hardness <Ni, excellent anti-corrosion effect, and excellent durability. [Effects of the Invention] As described above in detail, according to the present invention, a material having high mold releasability for the radiation-curable resin of the replica material, e.g. , SzgAQe periodic table IVa-VIa
Since an inorganic thin film protective layer made of a type of nitride or carbide of group metals, especially Ti, is provided, the releasability between the resin and the stamper during replica production is improved, and deformation of the pre-pits and pre-grooves of the stamper is prevented. In addition to improving durability and service life, the surface hardness is high and serves as a corrosion prevention layer on the metal surface, which further improves durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a stamper according to an embodiment of the present invention and its manufacturing process. 1...Pre-pit, 2...Pre-groove, 3...Photoresist film, 4...
Protective layer (Si, An, metals from group rVa to Vla of the periodic table, especially Ti nitride, carbide), 5...Ni layer (conductive layer), 6...Ni plating layer ,7...
...Anaerobic thermosetting adhesive, 8...Reinforcement material, 9
...Glass substrate.

Claims (3)

[Claims] (1) An optical disc stamper for producing an optical disc replica using a radiation curable resin, characterized in that an inorganic thin film protective layer having high mold releasability against the radiation curable resin is formed on the stamper surface. . (2) The optical disc stamper according to claim 1, wherein the stamper surface is made of a nickel layer on which pre-pits and pre-grooves are formed. (3) The optical disk stamper according to claim 1 or 2, wherein the inorganic thin film protective layer is made of nitride or carbide of any one of silicon, aluminum, and titanium.