JPS6276039A - Manufacture of optical information recording medium - Google Patents

Abstract

PURPOSE:To reduce the forming time of the 2nd mask by preparing the 1st mask having a common pattern in advance, transferring the common pattern as required and adding only the specific pattern only so as to form the 2nd mask. CONSTITUTION:The 1st mask 16 having a common pattern 15 is formed to the 1st transparent base 11 made of a quartz glass. A thin film 18 and a positive type photo resist 19 is covered to the 2nd transparent base 17 made of a quartz glass, the 1st mask 16 is used as a mask and an ultraviolet ray 20 is irradiated to the full face to expose and develop the resist 19, the common pattern 21 similar to the common pattern 15 is formed to the 2nd pattern forming thin film 18 by applying etching. Then an electronic ray resist 22 is coated to the entire face to expose the pattern of the specific guide other than the common buide to the resist 22 by the direct picture drawing by means of an electron ray 23 and the specific pattern 24 is added to the common pattern 21 to from the 2nd mask 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a reproduction-only, additional recording, or rewritable optical information recording medium that optically records, reproduces, and erases information.

[Conventional technology]

In recent years, optical information recording media (hereinafter referred to as "medium") have become popular.

) is attracting attention as a high-density, large-capacity memory device. The reason why this optical information recording medium has high density and large capacity is that the bit, which is the unit of recording information, is determined by the wavelength of light and the numerical aperture of the lens that focuses the light on the recording layer, and its size is 1 μm. This is because it can be made to a certain degree. Note that reproduction is also performed by optically reading out the presence or absence of this bit. However, in order to accurately record and reproduce information, a precise mechanical mechanism with an electronic control system is required, which necessitates making the optical memory device larger.
The structure shown in Figure 4 has come to be adopted. In the figure, a medium substrate 1 is made of glass, has a disk shape with a cylindrical through hole 1a in the center, and has a recording layer formed on its main surface 2, which is formed by etching. Concentric guide grooves 3 (hereinafter referred to as ``pre-grooves'') that facilitate the tracking of light for recording and reproducing information, and small recesses 4 (hereinafter referred to as , "prepit"). Note that the pregroove or prepit will be collectively referred to as a guide section hereinafter.

When manufacturing a media substrate having such a guide portion, conventionally, a pattern forming thin film deposited on the main surface of a glass substrate is subjected to photolithography and etching.
A disk-shaped or square plate-shaped mask having a pattern for forming a guide portion is formed, and then a resist film coated on the main surface of a disk-shaped glass substrate that will become a media substrate is applied to the mask. The pattern was transferred to the resist film by exposure and development through a resist film, and finally the surface of the glass substrate was etched using the 4-turn resist film as a mask.

[Problem that the invention seeks to solve]

However, the type, position, and shape of the guide portions are not always constant, and each time there is even a slight change in the number of turns, a new mask must be manufactured and the pattern must be transferred to form the media substrate. I had to.

[Means for solving problems]

In order to solve these problems, the present invention first forms a first mask having only a pattern common to a plurality of types of media substrates, and then transfers the common pattern and also transfers the pattern of the unique portion. A second mask is formed to which a second mask is added, and this is used to form a medium substrate.

[Effect]

When manufacturing a plurality of types of media substrates having a common pattern, the first mask is shared by the various substrates and is individually executed only from the stage of forming the second mask.

〔Example〕

Next, one embodiment of the present invention will be described using FIGS. 1 and 2. Note that FIG. 1 is a cross-sectional view showing the manufacturing process of the medium substrate, and FIG. 2 is a plan view of the completed medium substrate.

Introduction Outer diameter 130 mm, inner diameter 6 [rIo11 thickness 2
．． 3 rrtm first transparent substrate 1 made of quartz glass
1 is prepared, and after precision polishing the main surface, a fourth pattern forming thin film 12 made of approximately 7001 chromium (Cr) is deposited by sputtering, and a positive electron beam is applied on top of it. Resist 13 was applied. As the electron beam resist 13, PBS manufactured by Chisso Corporation was used. Next, the electron beam 14
The common guide part (
In this embodiment, a pregroove pattern is exposed (FIG. 1(m)).

Next, the exposed resist 13 is developed with a developer prepared by adding water to a mixture of 5-methyl 2-hexanone and 2-pentane.
Form a resist pattern. Next, using this resist pattern as a mask, the first pattern forming thin film 12 is etched using a mixed solution of ceric ammonium nitrate and perchloric acid.

Thereafter, by removing the resist 13 with sulfuric acid, a first mask 16 having a common pattern 15 for forming a common guide portion is formed (FIG. 1(b)). In addition,
Although omitted in the figure, the common pattern has a radius of 40
It is assumed that grooves with a width of 1.0 μm are formed concentrically at a pitch of 2.0 μm within the range from mm to 60 [IT[l+].

The main surface of a second transparent substrate 1T made of a quartz glass substrate similar to the first transparent substrate 11 described above is precisely polished, and a second pattern forming thin film 18 made of chrome (thickness: 700 Å) is formed.
), and then a positive photoresist (
In this example, AZ-1350) 19 manufactured by Hoechst was coated. The film thickness of the resist 19 was set to 1000A. Next, using the first mask 16 as a mask, the entire surface was irradiated with ultraviolet rays 20 to expose the resist 19 (FIG. 1(C)).

Next, development is performed using an AZ developer manufactured by Hoechst, and etching is performed to form the second pattern forming thin film 1.
A common pattern 21 similar to the common pattern 15 was formed on the substrate 8 (FIG. 1(d)).

Next, on the main surface on which the common pattern 21 is formed, an electron beam resist 22 similar to the resist 13 described above is applied to the entire surface, and the resist 2 is formed by direct drawing with an electron beam 23.
2, the pattern of the unique guide portion other than the common kite portion is exposed (FIG. 1(e)).

Next, the resist 22 is developed and the second pattern forming thin film 18 is etched in the same manner as the resist 13 described above (FIG. 1(f)), and the resist 22 is removed in the same manner as described above. A second mask 25 is formed in which a unique pattern 24 is added to the common pattern 21 (FIG. 1(7)). Note that the unique pattern 24 has a radius of 3
A groove of 1 μm width is 2 μm within the range of 40+ runs from 5 plates.
It is assumed that they are formed concentrically at a pitch.

Next, the outer diameter is 130 mm, the inner diameter is 15 m, and the thickness is 1.2 r.
rrn.

A third transparent substrate 26 made of soda lime glass and processed into a disk shape with an eccentricity of 10 μm or less was prepared. Then, on one main surface of this substrate 26, which has been subjected to precision polishing and low-temperature ion exchange treatment, a pattern forming thin film 27 made of silicon oxide (SIO2) is coated to a thickness of 1500× by vapor deposition to form a kite portion. I corrected it. A photoresist 29 similar to the resist 19 described above was coated thereon with an intermediate layer 28 made of hexamethyldisilazane interposed therebetween. Intermediate JΔ28 is the pattern forming thin film 2T and resist 29
This is to increase the adhesion with the The film thickness of the resist 29 was 100 OA. Next, using the second mask 25 as a mask, the resist 29 was exposed by contact exposure with ultraviolet rays 30 (FIG. 1(h)).

The exposed resist 29 was developed in the same manner as the resist 19 described above, and the pattern forming thin film 21 was dry etched using the resist as a mask. Prior to etching, post-bake resist 29 at 100℃ for 3 times.
This was done for 0 minutes. CF4 is used as the etching gas, and the flow rate is 308 CCM.

Total pressure 0.2 Torr, high frequency 7 and force density 0.2 W
/ crA conditions. After etching, the remaining resist is removed by ashing using oxygen gas.
A medium substrate 33 having a common guide section 31 and a unique guide section 32 was formed (FIG. 1(1) and FIG. 2).

The method for creating the medium substrate 33 is the same as described above, but when creating another medium substrate having the common guide portion 31, the first mask 16 described above can be shared. There is no need to perform the step of creating the first mask 16 again, and it is sufficient to start from the step of FIG. The creation time can be reduced by about 30 minutes.

Next, two media substrates provided with such guide sections were prepared, and a recording layer made of tellurium (Te) was coated to a thickness of 30 OA on each section to allow additional recording. After that, the recording layer is placed facing each other, and the outer periphery of the substrate and the through hole: l! A smoother was placed and fixed near each f, and a sand inch-shaped medium having a void inside was entirely prepared.

In addition, in the manufacturing process of the media substrate mentioned above, all the resists used were of positive type, or Necal may also be used.
Both may be used together. For example, in the process shown in FIG. 1(e), a negative resist (C0P manufactured by Mead Chemical Co., Ltd.) is used as a substitute for the resist 22, and the electron beam is irradiated only on the portions of the specific pattern forming area that will not become grooves. .

Further, in the steps shown in FIGS. 1(a) and 1(6) described above, direct drawing was performed using an electron beam resist, but a photoresist may be applied and exposed through a desired mask.

In addition, in the above-mentioned embodiments, all positive resists were used in order to finally use the groove portions without the pattern forming thin film 27 as guide portions, but for example, in the step of FIG. 1(h), the resist 29 was Instead, a negative resist is used,
The portions of the pattern forming thin film 27 corresponding to the portions of the common pattern 21 and the unique pattern 24 where the second pattern forming thin film 18 is present may be removed by etching, and these portions may be used as guide portions.

Furthermore, the portion (convex portion) where the pattern forming thin film 27 is present may be used as the guide portion.

Although an example in which a pig group is provided as a guide portion has been described above, the same applies to a case in which a pre-pit or both of them are provided. Further, in that case, the common guide portion may be only a pregroove, conversely, only a plevis groove, or both.

In the above-described embodiment, since a glass plate strengthened by ion exchange treatment is used as the light-transmitting substrate 26, it will not be broken even if it is rotated 20,000 times per minute. In addition, the surface hardness is improved by 5/- to 50 to 100 compared to that without the same treatment, making the surface less likely to be scratched.

Furthermore, deterioration due to precipitation of Na ions can be prevented, and a decrease in light transmittance can be prevented. - Temperature 60°C as an example
FIG. 2 shows the change over time in the light transmittance of the substrate measured at a relative humidity of 90% RH. In the figure, (a) is the case according to the above example, and (b) is the case where ion exchange treatment was not performed, and it can be seen that the characteristics were significantly improved by ion exchange treatment.

In addition, although a low temperature ion exchange method was used in the above example,
A similar effect can be obtained by high-temperature ion exchange method or air-cooling strengthening method, at least in terms of preventing destruction and scratches as described above. Furthermore, the same effect can be obtained not only when using soda lime glass but also when using other glasses such as borosilicate glass or aluminosilicate glass.

Although the common guide portion 31 and the unique guide portion 32 are formed on the pattern forming thin film 27 adhered to the surface of the transparent substrate 26, it is not necessary to do so. It may be formed over both. Furthermore, it may be formed directly on a light-transmitting substrate, but considering the presence of etching unevenness, scratches, bubbles, etc. due to compositional fluctuations, it is necessary to When using the surface layer of the transparent substrate itself, it is preferable to separately provide a dedicated thin film as in the above embodiment.

Note that prior to forming the pattern-forming thin film 27, the surface of the transparent substrate 26 may be coated with aluminum oxide or the like, and the pattern-forming thin film 27 may be formed thereon to increase its adhesion.

Furthermore, such a pattern forming thin film 2T is not limited to a silicon oxide film, but may include, for example, elements of Groups 1, 2, and 2 of the periodic table, or compounds thereof, or oxides or nitride films of these elements. Alternatively, a light-transmitting material such as a chalcogen element, a compound thereof, or an oxide or nitride film thereof may be appropriately selected. This pattern-forming layer does not necessarily have to have a stoichiometric composition as long as it can be formed with unevenness by etching.

Further, depending on the material, the etching method for the pattern forming layer is arbitrary, and is not limited to the dry method, but may also be a wet method.

Further, although the pattern is formed only on one main surface of the light-transmitting substrate 26, it may be formed on both surfaces.

In the above embodiments, T@ is used as the material of the write-once recording layer.
However, chalcokene elements other than Te such as Ss, Gs
Chalcogen compounds such as To, chalcogen oxides such as Te0X, elements of Groups ■, ■, and ■ of the periodic table, their compounds, their oxides, nitrides, and organic substances added with light absorbers. The material is not particularly limited. In addition to the above-mentioned materials, materials for recording layers other than write-once types, such as rewritable types, include alloys whose main components are transition metals such as Mn and elements of Group V of the periodic table, G
An alloy containing a transition metal such as dFeCo and a rare earth element as main components can also be used. Furthermore, in the case of reproduction only, it is also possible to use materials that have a high reflectance for the light used, such as AuXAs', Pt, and A4 Cu.

In addition, although an air sandwich type medium is shown in the above embodiments, other structures such as an air incident type or a close sandwich type may also be used.Also, two substrates each having a recording layer are pasted together. Alternatively, the number of substrates covered with the recording layer may be one, and a simple light-transmitting substrate without the recording layer may be laminated to this for protection. Further, it is not necessarily necessary to have a laminated structure, and in that case, if light is irradiated from the recording layer side, the substrate does not necessarily have to be translucent.

Although an example has been described in which quartz glass or soda lime glass is used as the transparent substrate 11.17 or 26, other materials such as aluminosilicate glass, borosilicate glass, etc. may be used, and polymethyl methacrylate glass may also be used. ) (PMMA) or other plastics or ceramics.

Further, as mentioned above, when the optical information recording medium is composed of one substrate provided with a recording layer and information is recorded or read from above the recording layer, the substrate for the medium may be made of, for example, an At alloy. Metals such as may also be used.

Further, although chromium is used as the first and second pattern forming thin films 12 and 18, other than chromium, chromium may also be used, such as elements in groups I, IV, and V of the periodic table, chalcogen elements, their compounds, their oxide films, or It may also be a nitride film or the like.

〔Effect of the invention〕

As explained above, according to the present invention, a first mask having a common pattern is prepared in advance, the common pattern is transferred as necessary, and only a unique pattern is newly added to the second mask. By forming the mask, it is possible to shorten the time 11d for creating the second mask, and a high-quality medium substrate with a kite portion can be obtained at low cost.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing one embodiment of the present invention, where Figure 1 is a cross-sectional view of the process, Figure 2 is a plan view, and Figure 3 is a diagram showing changes in light transmittance of a glass substrate over time. , FIG. 4 is a perspective view showing an example of the structure of the medium substrate. 11...First light-transmitting substrate, 12...Thin for first pattern formation, 15, 21・φ common pattern, 1
6...First mask, 17...Second light-transmitting substrate, 18...Second pattern forming thin film, 24...
- Unique pattern, 25...Second mask, 26...
...Third transparent substrate, 27... Thin film for pattern formation (layer for pattern formation), 31... Common kite portion,
32... Unique guide portion, 33... Medium substrate. % Ganto Gyoda Hoya Co., Ltd.

Claims (1)

[Claims] In a method for manufacturing an optical information recording medium in which a recording layer is formed on the main surface of a medium substrate, a common pattern is formed on a pattern-forming thin film formed on the main surface of a transparent first substrate. forming a first mask; transferring the common pattern of the first mask to a pattern-forming thin film formed on the main surface of a light-transmitting second substrate; and then additionally forming a unique pattern to form a second mask; and a step of transferring a common pattern and a unique pattern of a second mask to a pattern forming layer located on the main surface of a third substrate to form a medium substrate. Production method.