JPH0695395B2 - Method of making substrate of flat information recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a groove or a pit row in a substrate of a flat information record carrier.

2. Description of the Related Art The etching technique for forming a fine pattern on the surface of a substrate is an essential technique for manufacturing information recording media such as semiconductor integrated circuits, printed circuit boards, transparent conductive films, and optical discs. Particularly in recent years, dry etching process has been attracting attention due to demands for pattern miniaturization and process automation. Although the dry etching process has already been put to practical use in the manufacture of VLSI, this technology has been adopted in the production of optical disc substrates for forming even finer submicron patterns.

Hereinafter, a method of performing pattern formation on the optical disk substrate by dry etching will be described with reference to FIG.

First, the photoresist 2 is uniformly applied to the surface of the glass substrate 1 that has been highly accurately polished (FIG. 2 (a)). Then, while rotating the glass substrate 1, the photoresist 2 is irradiated with the laser light 3 which is modulated in accordance with a desired pit row or groove structure (FIG. 2 (b)). By developing this, the exposed region of the photoresist 2 is removed, and a concentric or spiral uneven pattern appears on the surface (FIG. 2 (c)).

Next, the glass substrate 1 with the concave-convex pattern is subjected to gas plasma 4 to etch the glass substrate 1. CHF ₃ or the like is used as the etching gas. At this time, the plasma 4 generated by the discharge has a function of vertically incident on the surface of the glass substrate 1 to sputter the glass, and at the same time, selectively reacts with SiO ₂ which is the main component of the glass to decompose the glass.

After etching is advanced to a predetermined depth (see FIG. 2).
(d)) If the remaining photoresist 2 is removed by plasma ashing using O ₂ gas, a glass substrate for an optical disc having a predetermined concentric or spiral groove or pit row on the surface is obtained ( Fig. 2 (e)).

Problems to be Solved by the Invention In such a conventional method, since a photoresist is used as a mask for forming a predetermined groove or pit row on a glass substrate, a wet process called development is required. . For this reason, there is a problem that impurities adhere to the surface of the glass substrate and cause defects in the formed pattern.

Means for Solving the Problems In order to solve the above problems, the present invention uses a material whose crystal state is changed by heating as a mask for forming a predetermined groove or pit row.

Action The action of this means is as follows.

In the dry etching process, the rate at which a material is etched varies depending not only on the type of material but also on the crystalline state of materials having the same composition. Therefore, if a material whose crystal state changes by heating is attached to the substrate and a predetermined portion is heated by changing the crystal state of the portion by a method such as irradiating this with a laser beam, By etching the substrate, the etching rate of the heated region of the material attached to the surface of the substrate is different, and the concavo-convex pattern can be formed. If etching is continued even after the etching progresses and the glass surface is exposed,
This uneven pattern is transferred to the glass surface.

In this embodiment, since it is not necessary to develop after the exposure with the laser light, the problems of the conventional method described above do not occur.

Example An example of the present invention will be described with reference to FIG.

First, the Te oxide film 5 is vapor-deposited on the surface of the glass substrate 1 which is highly accurately polished (FIG. 1 (a)). At this time, the Te oxide film 5 is in an amorphous state.

By irradiating the Te oxide film 5 with the laser light 3 which is modulated in accordance with a desired pit row or groove structure while rotating the glass substrate 1, the irradiated region is heated to an amorphous state. The film that was once crystallized (first
(Figure (b)).

Next, when the glass substrate 1 is etched using Ar gas, the regions of the Te oxide film 5 in the amorphous state are etched faster than the regions in the crystallized state, and an uneven pattern appears on the surface (first). Figure 1 (c)). When the etching is continued, all the amorphous regions of the Te oxide film 5 are removed by etching, and the glass surface is exposed. From this point, when the etching gas is switched to CHF ₃ and etching is continued, the plasma generated by the dissociation of the CHF ₃ gas reacts with SiO ₂ , which is the main component of glass, to selectively etch the glass surface. Then, if all the remaining Te oxide film is also removed by etching, a glass substrate for an optical disk having a predetermined concentric or spiral groove or pit row on the surface is obtained (FIG. 1).
(e)).

In this example, the Te oxide is in an amorphous state at the beginning of vapor deposition, and the laser-irradiated portion is crystallized. However, if the vapor-deposition material is appropriately selected, conversely, before laser irradiation, The entire film is in a crystalline state and the irradiated portion can be transformed into an amorphous state. In this case, the irradiated area is etched quickly, and a concavo-convex pattern reverse to that of this embodiment is obtained.

Further, as the material to be attached to the glass substrate surface, in addition to the Te oxide of the present embodiment, a material containing a chalcogenite-based element such as Se, Sn, Sb, Pb, Bi, As, etc. it can.

Further, as the glass substrate 1, it is possible to improve the etching rate by using quartz glass or the like in addition to soda glass. Further, it is also possible to transfer the grooves engraved in the glass substrate 1 once to a metal plate and then transfer this to a substrate such as acrylic, and use this as an optical disk substrate.
In this case, a large number of optical disc substrates having the same groove structure can be duplicated.

Further, as the etching gas, CHF ₃ ,
In addition to Ar and Ar, CF ₄ , C ₂ F ₆ , C ₃ F ₈ , NF ₃ , CCl ₄ or the like can be used.

As described above, according to the present invention, in the dry etching of the glass substrate, the dry etching process which does not require the wet process can be performed by using the material whose crystal state is changed by heating as the mask. Since the concave-convex pattern with high accuracy can be formed on the substrate, an optical disc substrate with few defects can be produced.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method of manufacturing an optical disk substrate in one embodiment of the present invention, and FIG. 2 is a process drawing showing a method of manufacturing a conventional optical disk substrate. 1 ... glass substrate, 2 ... photoresist, 3 ... laser light, 4 ... gas plasma, 5 ... Te oxide film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mieko Ofukada 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-54-77105 (JP, A) JP-A-54- 134603 (JP, A)

Claims (6)

[Claims] 1. A method comprising the steps of: attaching a material that changes a crystalline state in response to a temperature change to a flat substrate; heating a concentric or spiral region of the material; and including the material. A step of causing a gas in a plasma state to act on the flat substrate, and forming a concavo-convex pattern corresponding to the heated area on the flat substrate. 2. A substrate for a flat information record carrier according to claim 1, wherein at least a portion of the flat substrate on which the concavo-convex pattern is formed is a material containing SiO ₂ as a main component. Method. 3. The flat plate-shaped information according to claim 1, wherein at least a portion of the lithographic substrate on which the concavo-convex pattern is formed is a material containing SiO ₂ and Na ₂ O as main components. Method of making substrate of record carrier. 4. A material containing at least one of Te, Se, Sn, Sb, Pb, Bi and As is used as the material whose crystal state is changed by heating. A method for producing a substrate of the flat information recording carrier described in the above. 5. The method for producing a substrate for a flat information record carrier according to claim 1, wherein a material containing Te oxide as a main component is used as the material whose crystal state changes by heating. 6. Ar, CHF ₃ , CF ₄ , as a gas in a plasma state
The method for producing a substrate for a flat information record carrier according to claim 1, wherein at least one of C ₂ F ₆ , C ₃ F ₈ , NF ₃ and CCl ₄ is used.