JPH0359493B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium on which information can be optically recorded, reproduced, or erased.
In particular, the present invention relates to an optical information recording medium having a guide portion for facilitating the tracking of light for recording, reproducing, or erasing information.

[Conventional technology]

Conventionally, as this type of optical information recording medium, there has been an optical information recording medium having a Sanderch structure as shown in FIG. 5, for example. Note that FIG. 5a is a sectional view, and FIG. 5b is a partially enlarged sectional view of a portion covered with a recording layer.

This medium consists of transparent substrates 3 and 4 having recording layers 1 and 2 adhered to one main surface, a ring-shaped inner spacer 5 that arranges the transparent substrates 3 and 4 at a desired distance, and an outer spacer. The basic structure is a sandwich structure consisting of a spacer 6 and an adhesive 7 that fixes the inner spacer 5 and the outer spacer 6 to the transparent substrates 1 and 2, respectively, and in which the recording layer 1 and the recording layer 2 face each other. This is what we do. Furthermore, as shown in FIG. 5b, the surface of the light-transmitting substrate 3 on which the recording layer 1 is attached is provided with uneven parts (note that the light-transmitting substrate 4 is also similar, so the description thereof will be omitted). ), a recording portion 8 whose convex portion is covered with a recording layer 1 for recording information.
The concave portions form guide portions 9, respectively.
A plurality of recording sections 8 and guide sections 9 are arranged concentrically and alternately. The depth of the guide section 9 is determined by the intensity of the reflected light from the top surface of the recording section 8 and the depth from the bottom surface of the guide section 9 when the laser beam is irradiated from the direction indicated by the arrow 10 in the figure, that is, from the side of the transparent substrate 3. The intensity of the reflected light is set to be significantly different due to interference with each irradiation light (for example, when the wavelength of the laser light is 830 nm, it is about 800 Å). Therefore, traditional media
The recording section 8 and the guide section 9 can be identified by creating a difference between the intensity of the reflected light from the recording section 8 and the intensity of the reflected light from the guide section 9 due to the interference effect caused by the optical path difference of the irradiated light. did.

[Problem that the invention seeks to solve]

However, as described above, in conventional optical information recording media, the recording section 8 and the guide section 9 are arranged in a concave-convex relationship for identification by providing a difference in reflected light intensity. For example, if you want the reflected light intensity ratio (ratio based on the larger reflected light intensity) to be 0.8 or less, the depth is λ/(8n) (where λ is the extension of the irradiated light and n is ) is the refractive index of the substrate), and its accuracy is ±
5%, and it was extremely difficult to form recesses in this range.

The present invention has been made to eliminate this drawback, and its purpose is to provide an optical information recording medium that can be identified without having an uneven relationship between the guide part and the recording part. .

[Means for solving problems]

In order to achieve the above-mentioned object, the optical information recording medium of the present invention comprises a substrate, a thin film formed on the substrate and having a lower dry etching resistance than the substrate, and a recording layer formed on the thin film. The surface of the thin film located in the same plane is divided into a guide part and a recording part, and at least one of the guide part and the recording part is made rough, and the surface of the guide part is roughened. and the surface roughness of the recording section is made different, and the recording layer is deposited on the recording section. Moreover, as a preferable embodiment, in the optical information recording medium having the above-mentioned characteristics, the surface roughness of the guide portion is rougher than the surface roughness of the recording portion. Note that the substrate of the present invention includes not only single substrates such as glass substrates or aluminum substrates, but also those in which an intermediate layer for improving the adhesion of the thin film is provided on these single substrates.

[Effect]

In the optical information recording medium of the present invention, the surfaces of the thin film having lower dry etching resistance than the substrate are divided into the guide portion and the recording portion, which are located in the same plane. At least one surface can be easily and uniformly roughened to a predetermined surface roughness.
In addition, the surface of the guide section is made rougher than the surface of the recording section,
Alternatively, since the surface of the recording section is made rougher than the surface of the guide section, the intensity of reflected light from the surface of the recording section and the surface of the guide section can be made different.

〔Example〕

An embodiment of the optical information recording medium of the present invention will be described in detail with reference to FIGS. 1 and 2. The basic structure of the optical information recording medium of this example is the same as that shown in FIG. 5a above, so the explanation thereof will be omitted.
The shape of the substrate, which is different from conventional media, will be explained in detail. Further, FIG. 1 is a partially enlarged sectional view showing a recording layer support base 11 having a recording layer 16 deposited thereon, which corresponds to a conventional light-transmitting substrate 3 having a recording layer 1 deposited thereon, and FIG. 1 is a partially enlarged sectional view showing a process of forming a guide portion and a recording portion on the recording layer support base 11. FIG.

First, as shown in FIG. 1, the recording layer support base 11 of this example includes a disk-shaped glass substrate 12 having an outer diameter of 130 mm, an inner diameter of 15 mm, and a thickness of 1.2 mm and having a through hole in the center.
(for example, soda lime glass) and a silicon oxide film 13 (film thickness: 1000 Å) deposited on this glass substrate 12. This silicon oxide film 13 has surfaces located in the same plane as shown in the figure. The substrate of the present invention corresponds to the glass substrate 12 in this embodiment, and the thin film having lower etching resistance than the glass substrate 12 corresponds to the silicon oxide film 13. A part of the surface of the silicon oxide film 13 of the light-transmitting substrate 11 is formed as a rough surface (maximum surface roughness: 300 Å, average distance between concave and concave or convex and convex portions of the rough surface: 2000 Å). A surface with a smaller maximum surface roughness than that of the guide portion 14 (maximum surface roughness:
20 Å). A recording portion 16 (thickness: 200 Å) made of Te, which is a write-once recording material, is deposited on the recording portion 15, and a Te film 17 is also deposited on the guide portion 14. Further, the width of the guide portion 14 is 1 μm,
The width of the recording portions 15 is 2 μm, and a plurality of recording portions 15 are formed alternately in concentric circles.

Next, the guide section 1 is attached to the recording layer support base 11 of this example.
4 and the recording section 15 will be explained based on FIG.

First, a glass substrate 12 whose main surface is precisely polished is
(Surface maximum roughness: 20 Å) A silicon oxide film 13 is deposited thereon by electron beam evaporation to produce the recording layer support base 11. Next, this silicon oxide film 13
A photoresist film 18 (for example, a diluted version of AZ-1350, a positive resist manufactured by Hoechst Co., Ltd., and its film thickness is 1000 Å) is applied on top, and
Next, this photoresist film 18 is prebaked (temperature: 90° C., time: 30 minutes), and then the photoresist film 18 is exposed to light using an Ar laser 19 at a position that will become the guide portion 14 (FIG. 3(a)). Next, the photoresist film 18 was coated with an AZ developer (manufactured by Hoechst).
The photoresist pattern 20 was formed by developing and post-baking (temperature: 100° C., time: 30 minutes) (FIG. 2(b)). Next, using this photoresist pattern 20 as a mask, a silicon oxide film 13 is deposited.
Dry etching was performed using CF ₄ gas to form a guide portion 14 on the surface of the silicon oxide film 13 (FIG. 3(c)).
Note that this etching condition is based on a gas flow rate of 30 standard cm
Minitsutsu (SCCM), total pressure 0.3Torr, high frequency power density 0.3W/ ^cm2 . Even if dry etching is performed on the glass substrate 12 under these etching conditions, the surface of the glass substrate 12 will not only be roughened but also not damaged. That is, in this embodiment, since the silicon oxide film 13 having lower etching resistance than the glass substrate 12 is provided on the glass substrate 12, the guide portion 14 can be easily roughened. The photoresist pattern 20 is removed using oxygen gas to expose the recording section 15 (d in the same figure). Next, by vacuum evaporation method,
Te is deposited on the silicon oxide film 13 to form the recording layer 1.
6 is stacked on the recording section 15 (e in the figure). At this time, the Te film 17 is also deposited on the guide portion 14.

The reflectance of the guide portion 14 and recording portion 15 formed as described above is measured by laser light (wavelength is 830 nm, irradiated from the same direction as the arrow shown in FIG. 5b) from the glass substrate 12 side. ), the reflectance of the guide section 14 is about 25%, while the reflectance of the recording section 15 is about 40%, so the reflected light intensity ratio is about 0.6, which is sufficient for the guide section 14 and the recording section. part 15 could be identified.
Here, when the relationship between the reflectance and the surface roughness of the guide portion 14 is examined, it becomes curve A in FIG. 3. That is,
The reflected light intensity ratio is 0.8 or less with respect to the reflectance of 40% of the recording part 15 (surface roughness: 20 Å) when the surface roughness is 150 Å or more.
As long as the roughness is within the range of 1000 Å, at which the reflectance of the material is about 5% and the reflection from the glass substrate 12 becomes indistinguishable, it can be sufficiently identified. That is, the lower limit of the surface roughness is not constant because the reflected light intensity ratio changes depending on the surface roughness of the recording section, but the upper limit of 1000 Å is approximately constant if the substrate 12 is made of glass. Furthermore, the relationship between the concavity and concavity or convexity and convexity of the guide part 14, that is, the relationship between the average spacing of the surface roughness and the reflectance, is as shown in curve B in Figure 4, and if it is 5000 Å or less, the reflected light The intensity ratio is 0.8
The following is true. In this example, the layer to be roughened is a thin film such as a silicon oxide film, which has lower dry etching resistance than the glass substrate, so that the surface roughness can be easily and uniformly within the predetermined range described above. can do.

As described above, the present invention is not limited to the above-mentioned embodiments, but may be as follows.

First, in the embodiment described above, the surface roughness of the guide portion is made rougher than that of the recording portion, but it is possible to identify the guide portion even if the surface roughness is reversed. However, if the surface of the recording area is made rougher, it becomes necessary to consider the reflectance and the influence of the surface roughness of the recording area on the recording sensitivity, and the surface roughness must be determined based on the balance between the two. It will stop happening. Therefore, it is preferable to use a guide section with a rough surface rather than a recording section, which can desirably handle both reflectance and recording sensitivity caused by surface roughness separately. Further, between the glass substrate and the thin film forming the guide section and the recording section, an intermediate layer (for example, an element, a compound, or a compound of a group, group, or group of the periodic table) is provided to improve the adhesion of the thin film. The substrate may be formed by interposing a material (oxide, nitride, etc.). Furthermore, the thicknesses of these thin films and intermediate layers are not particularly limited. Therefore, when the rough surface of the guide part or the recording part is formed by coating a glass substrate with a thin film, for example, as in the above embodiment,
It may be applied to both thin films and glass substrates. Furthermore, thin films with lower dry etching resistance than the substrate include elements of groups, groups, groups of the periodic table,
It may be a compound or an oxide or nitride thereof.

Further, in the above embodiments, soda lime glass was used as the glass substrate, but other glasses such as multi-component glasses such as quartz glass, aluminosilicate glass, aluminoborosilicate glass, or ceramics may also be used. It may also be treated glass. Furthermore, the basic structure of the optical information recording medium is not limited to the Sandermanch structure, and can be appropriately determined depending on the recording material, recording method, etc. In addition, the basic structure of the optical information recording medium is not a sandwich structure, but a recording layer is deposited on a single substrate, and this recording layer is coated with a transparent protective film or a transparent sealing material made of glass or the like. When applying light for recording, reproducing, or erasing information from the protective film side, the substrate may be made of a non-transparent material such as aluminum.

Further, in the above embodiment, the guide portion is formed by using a smooth silicon oxide film as a rough surface, but conversely, the recording portion may be formed by using a smooth surface as a rough surface. For example, in the case of the substrate of the above embodiment, the silicon oxide film is first roughened to have a surface roughness of 300 Å,
Next, a positive type photoresist film is applied to the surface, and then the photoresist film is exposed to light using an Ar laser in the area that will become the recording area, and then developed. Next, the exposed rough surface was treated with _CF4 gas at a gas flow rate.
30SCCM, total pressure 0.2Torr, high frequency power density 0.2W/
Etch under cm ² conditions to form a recording part with a smooth surface. Then, the photoresist film is removed to produce a substrate similar to that of the previous embodiment.

Furthermore, in the embodiment described above, the same film as that on the recording section is also coated on the guide section. However, the guide portion does not necessarily need to be coated with a film similar to the recording layer, and may be made of other materials, or may not be coated with a film.

Further, in the above embodiment, Te, which is a write-once recording material, was used as the recording layer, but other materials, such as
Se, GeTe<TeC, etc., and rewritable recording materials.
It may be TbFe, GdTbFe, or it may be an organic material to which a light absorbing material is added. Further, the recording layer may be multilayer. Further, although the above embodiment uses a concentric guide portion (pregroup), the same effect can be obtained with a spiral pregroup, a track number, a sector, a sector number, and other guide portions.

〔Effect of the invention〕

As described above, according to the optical information recording medium of the present invention, the surface of at least one of the guide section and the recording section in the thin film having lower dry etching resistance than the substrate is roughened, and the surface roughness of the guide section and the recording section are made rough. Since the surface roughness is different, the guide part and the recording part can be identified by the difference in the intensity of reflected light. Moreover, since the rough surface is formed as a thin film having lower dry etching resistance than the substrate, the rough surface with a predetermined surface roughness can be easily and uniformly formed.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged cross-sectional view showing an embodiment of the optical information recording medium of the present invention, FIG. 2 is a partially enlarged cross-sectional view showing the manufacturing process of an embodiment of the present invention, and FIG. 3 is a surface of a guide portion. FIG. 4 is a characteristic diagram showing the relationship between roughness and reflectance, and FIG. 4 is a characteristic diagram showing the relationship between average interval of surface roughness of the guide portion and reflectance. FIG. 5 is a diagram showing a conventional optical information recording medium, in which FIG. 5A is a sectional view and FIG. 5B is a partially enlarged sectional view. DESCRIPTION OF SYMBOLS 11... Recording layer support base, 12... Glass substrate, 13... Silicon oxide film, 14... Guide part, 15... Recording part, 16... Recording layer.

Claims (1)

[Scope of Claims] 1. A substrate, a thin film formed on the substrate and having a lower dry etching resistance than the substrate, and a recording layer formed on the thin film, the thin film being formed within the same plane. The surface located at the guide portion is divided into a guide portion and a recording portion, and at least one of the guide portion and the recording portion is made a rough surface, and the surface roughness of the guide portion and the surface roughness of the recording portion are made different. . An optical information recording medium, characterized in that the recording layer is deposited on the recording section. 2. The optical information recording medium according to claim 1, wherein the guide portion has a rougher surface than the recording portion.