JPH0249231A - Production of glass substrate for optical memory disk - Google Patents

Abstract

PURPOSE:To improve accuracy and productivity by applying a silane coupling agent on the glass substrate, applying a photoresist to a specific thickness thereon, forming patterns of guide grooves for tracking/prebits and etching the glass substrate by an aq. acidic soln. with the patterns as a mask. CONSTITUTION:The photoresist 2 is coated to 1.0mum thickness on the glass substrate 1 coated with the silane coupling agent and the patterns of the guides for tracking and/or prebits are exposed and developed. The glass substrate 1 is etched by the aq. acidic soln. contg. hydrofluoric acid with the photoresist patterns as a mask 3, by which the substrate having the guide grooves and/or prebits is obtd. The sufficient etching rate is obtd. in this way and the productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a glass substrate for an optical memory disk.

[Prior Art] In a conventional method for manufacturing a glass substrate for an optical memory disk, Japanese Patent Application Laid-Open No. 1983-1999 discloses etching the glass by a reactive ion etching method in order to directly form guide grooves and/or pre-pits on the surface of the glass substrate.
This method has been proposed in, for example, No.-210547.

[Problems to be solved by the invention] Conventionally, reactive ion etching (R, 1, E, 1 method) has been used to directly form guide grooves and/or pre-pits on the surface of a glass substrate for optical disks, but the etching speed is The problem was that productivity was low due to the slow speed and the time required for vacuum evacuation and air supply in the process chamber.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems. A silane coupling agent is applied onto a glass substrate, and a photoresist is applied thereon to a thickness of 0.1 to 1.0 μm. a pattern having guide grooves and/or pre-pits for tracking of a light beam is exposed on the photoresist, the exposed photoresist is developed, and the self-developed photoresist is coated with the self-developed photoresist. The glass substrate is etched with an acidic aqueous solution using the pattern as a mask to form guide grooves and/or pre-pits directly on the surface of the glass substrate.Finally, the resist pattern is removed with an alkaline solution to form guide grooves and/or pre-pits. The present invention provides a method for manufacturing a glass substrate for an optical memory disk, which is characterized by obtaining a glass substrate having pre-pits.

Hydrofluoric acid can be used as the acidic aqueous solution (hereinafter referred to as treatment solution) used for etching in the present invention. Further, a treatment liquid containing hydrofluoric acid in at least one of ammonium fluoride aqueous solution, nitric acid, sulfuric acid, and hydrochloric acid can be used. The concentration of hydrofluoric acid in the treatment liquid is preferably in the range of 0.01 to 5% by weight, preferably 0.1%.
A range of 2% by weight, particularly 0.5-1% by weight is preferred.

In the present invention, etching is further performed with a processing solution containing hydrofluoric acid in the above range and at least one type of ammonium fluoride, nitric acid, sulfuric acid, and hydrochloric acid at a concentration of 50% by weight for each type. This is preferable because etching can be performed with less unevenness locally on the surface of the glass substrate to be etched.

Further, the temperature of the processing solution during etching is preferably lower when the concentration of hydrofluoric acid is high, and in particular, when the concentration is about 2% by weight or more, it is preferably about 20 DEG C. or lower, particularly in the range of 10 DEG C. to 18 DEG C.

[Function] In the present invention, the concentration of hydrofluoric acid and ammonium fluoride is lowered in order to prevent the Thl phenomenon between the resist, which serves as a mask during glass etching, and the glass.
By using nitric acid, sulfuric acid, and hydrochloric acid including hydrofluoric acid,
The life of the etching solution can be extended and the uniformity of etching can be improved.

It is also believed that by keeping the temperature of the aqueous solution low, it is possible to suppress the separation of the resist from the glass and enable etching of submicron patterns.

[Example] In Comparative Example 1, 24°C in an atmosphere of 60°C and 80%RH
Although the reproduced signal noise (dBml) after being left for a period of time has increased compared to the initial noise, the level of the initial noise is maintained in the example.

Further, in Comparative Example 2, although the initial noise level is maintained even after the above-mentioned leaving, the initial noise level is higher than that in the example of the present invention.

It is thought that when etching is performed by the RIE method, the etched glass surface is activated and tends to react with moisture in the air, making it more likely to cause burns. Burnt on the glass substrate surface is undesirable because it causes noise even after the recording film is coated. According to the wet etching of the present invention, the degree of activation of the glass surface described above is lower than that of the RIE method, and the initial noise level can be maintained even after being left in a high temperature and humid atmosphere.

[Effects of the Invention] The present invention has a sufficiently high etching rate since glass is etched with an acidic aqueous solution, and has the effect of being able to provide unprecedented productivity during mass production.

Furthermore, the present invention improves rj+,
This has the effect that the depth can be controlled with high precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the process of the present invention, FIG. 2 is an explanatory diagram of an embodiment of the wet etching processing apparatus of the present invention, and FIG. 3 is a schematic diagram of the process of a conventional example. ]...Glass substrate, 2...Resist film, 3
...Photomask, 4...Glass substrate for optical memory disk. 5...Developed glass substrate, 6...Atomized edgeant, 7...Nozzle, 8...
Turntable, 9...reaction container.謬 7 1ffl No. 7? 1 Koro and Go Yoku Go-4

Claims (3)

[Claims] (1) Apply a silane coupling agent on the glass substrate,
A photoresist is applied thereon to a thickness of 0.1 to 1.0 μm, a pattern having guide grooves and/or pre-pits for tracking the light beam is exposed on the photoresist, and the exposed photoresist is Develop,
etching the glass substrate with an acidic aqueous solution using the developed photoresist pattern as a mask to form guide grooves and/or pre-pits directly on the surface of the glass substrate;
A method for producing a glass substrate for an optical memory disk, which comprises finally removing the resist pattern with an alkaline solution to obtain a glass substrate having guide grooves and/or pre-pits. (2) The acidic aqueous solution according to claim 1 is 0.01 to 5% by weight.
A method for producing a glass substrate for an optical memory disk, characterized in that it contains hydrofluoric acid in a range of . (3) The acidic aqueous solution according to claim 1 is 0.01 to 5% by weight.
1. A glass substrate for an optical memory disk, characterized in that it contains hydrofluoric acid in the range of 10 to 50% by weight of at least one type of ammonium fluoride, nitric acid, sulfuric acid, and hydrochloric acid.