JP3198571B2 - Glass substrate surface treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a surface of a glass substrate, and more particularly to a method for treating a surface of a glass substrate used for manufacturing a master for an optical disk.

[0002]

2. Description of the Related Art In a manufacturing process of an optical disk master, first, a photoresist layer is formed on the surface of a glass substrate having excellent flatness and smoothness. Next, the formed photoresist layer is selectively irradiated with a laser beam and exposed to record original information. This is so-called mastering. After that, the exposed photoresist layer is subjected to a development process to produce an optical disc master.

[0003] A metal mask is formed on the basis of this master using electroforming. A plurality of mother boards are created from this metal mask, and a stamper is created from these mother boards. The stamper is mounted on a molding machine to perform mass production of optical disks. As can be seen from the manufacturing process, since the quality of the original master created first has a great influence on the quality of all optical disks as final products, strict manufacturing control is required. In particular, it is important to ensure the adhesion between the photoresist layer and the glass substrate in order to prevent the quality of the photoresist layer from deteriorating. If there is not sufficient adhesion, it is difficult to control the shapes of pits and grooves patterned on the photoresist layer. In order to ensure this adhesion, an aqueous solution-based coupling treatment method has been widely adopted. In this method, adhesion is ensured by coating the surface of a glass substrate with a coupling agent and then forming a photoresist layer.

[0004]

Heretofore, for example, a spin coating method has been adopted for applying a coupling agent to a glass substrate. In this method, a coupling agent is dropped and coated on the surface of a glass substrate rotating at a high speed in a resist coater. However, in this method, since the dropped coupling agent is shaken off at high speed, heat of vaporization is generated, the temperature of the substrate surface is reduced, and dew condensation occurs. Due to this effect, there is a disadvantage that sufficient adhesion to the photoresist layer cannot be obtained. In addition, when a coupling agent having a relatively high viscosity is used, dust in the air adheres to the surface of the glass substrate, and a solidified product of the coupling agent itself is formed. These foreign substances remain as defects on the master disk, which causes problems such as deterioration of the noise level of the optical disk as the final product or increase of the error rate.

In view of the above-mentioned drawbacks of the conventional method, a so-called dipping method has recently been adopted. In this method, a glass substrate is dipped or immersed in a processing solution obtained by diluting a coupling agent to a considerable extent with a predetermined solvent to perform a coating treatment of the coupling agent. In this dipping method, a drying process is performed to remove a solvent remaining on the substrate surface after the immersion process. Conventionally, as this drying method, so-called vapor drying using steam such as isopropyl alcohol, warm pure water drying, and the like have been adopted. In either case, since the drying process is performed under high-temperature heating, the coupling agent molecules bonded to the surface of the glass substrate are thermally affected and deteriorate, so that the adhesion to the photoresist layer is extremely reduced. There is.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides a method of drying a glass substrate capable of effectively preventing a decrease in the adhesion performance of a coupling agent applied on the glass substrate. The purpose is to provide a method. In order to achieve this object, a measure was taken in which a glass substrate surface-treated with a coupling agent was pulled up with a low-temperature liquid and dried.

Specifically, for example, a coupling agent is applied to a glass substrate using a treatment solution obtained by diluting the coupling agent with an excess solvent such as pure water or alcohol. As a method of application, dipping or showering can be used. Subsequently, the surplus coupling agent remaining on the surface is removed by cleaning the glass substrate. After this, isopropyl alcohol at 15 ° C to 70 ° C or
Is performed by lifting and drying the glass substrate from pure water at 15 ° C. to 60 ° C. These series of processing steps can be performed, for example, in a precision parts washing machine in which dust and the like in the atmosphere are completely shut off. Lastly, if necessary, the glass substrate is baked to remove water molecules between the coupling agent and the glass substrate.

[0008]

According to the present invention, a glass substrate having been subjected to a surface treatment is treated with a low-temperature liquid isopropyl
Pull up and dry with alcohol or pure water at 15 ° C to 60 ° C. By lifting and drying, residues or residues on the glass substrate surface can be uniformly and completely removed, and an extremely clean surface state can be realized. or,
Since a low-temperature liquid is used when pulling up and drying, there is no adverse effect such as thermal deterioration, and the original adhesion performance of the coupling agent can be maintained. If a photoresist layer is formed on a glass substrate that has been cleaned and provided with stable adhesion performance in this manner, a glass master for optical disks with low defects can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a flowchart showing a manufacturing process of a glass master disk for an optical disk employing the method for surface treating a glass substrate according to the present invention. First, in step S1, pre-cleaning of a glass substrate is performed. This pre-cleaning is mainly performed for the purpose of removing foreign matters such as fine particles adhering to the surface of the glass substrate. Specifically, for example, the glass substrate is dipped or immersed in pure water or pure water to which a surfactant is added, and washed by applying ultrasonic waves.

Next, in step S2, a coupling agent is applied to the surface of the glass substrate. For example, a water-soluble coupling agent is used. A coupling agent aqueous solution diluted with a large excess of water is supplied to the glass substrate surface. The dilution concentration is preferably set to 0.01 to 3 wt%. By using a diluent having a relatively low concentration, coagulation due to hydrolysis of the coupling agent can be suppressed, and treatment solution management becomes easy. As a coating method, the glass substrate may be simply dipped or dipped in an aqueous solution of a coupling agent, or the aqueous solution may be sprayed on the glass substrate as a shower.

Examples of the coupling agent include amino silane coupling agents such as N.β (aminoethyl) γ-aminopropyltrimethoxysilane, vinyl silane coupling agents such as vinyltriethoxysilane, and γ-glycidoxy. There are epoxy silane coupling agents such as propyltrimethoxysilane and phenyl silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane.

Next, in step S3, post-cleaning of the glass substrate is performed. For example, a surplus coupling agent is removed using a cleaning liquid such as pure water. This cleaning may be performed by simply dipping the glass substrate in pure water, or by blowing a shower of pure water or the like. If the excess coupling agent is not removed, lipophilic areas and hydrophilic areas are mixed on the surface of the glass substrate, and good adhesion cannot be obtained.

Next, low-temperature drying is performed in step S4.
Specifically, the glass substrate that has been subjected to the surface treatment and from which the surplus coupling agent has been removed is gradually pulled up from a low-temperature liquid and dried. As a liquid to be used, isopropyl alcohol (IPA) or pure water can be selected. I
When PA is selected, the temperature of the solution is set at 15 ° C to 70 ° C. When pure water is used, the temperature of the solution is 15
The temperature is set between 60C and 60C. Therefore, as used herein, the term "low temperature" refers to a temperature region at or near room temperature and includes a range that does not adversely affect the coupling agent thermally. The lifting of the glass substrate is performed gradually, and the speed is 0.01 to 20.
It is set to mm / sec. By performing this pull-up drying, residues or residues on the surface of the glass substrate are uniformly and uniformly removed, leaving no stains or the like. Therefore, an extremely clean surface state can be realized.

If vapor drying using IPA or pure water vapor is performed, the surface state is altered by the reaction between the coupling agent and vapor such as water, and the adhesion performance is extremely reduced. Further, even when the bath temperature is set to 60 ° C. or more, the coupling agent is similarly deteriorated even in the case of pull-up drying from hot pure water.

Subsequently, in step S5, baking of the glass substrate is performed. That is, the glass substrate is subjected to heat treatment in an inert gas atmosphere to remove water molecules and the like chemically bonded to the coupling agent molecules, thereby further improving the adhesion performance of the coupling agent film. However, it is possible to obtain a practically sufficient level of adhesion without necessarily performing baking.

After the surface treatment of the glass substrate is completed, a photoresist film is formed in step S6. This film formation is performed by applying a photoresist agent to a glass substrate at a predetermined film thickness and then heating. The photoresist layer thus formed adheres to the surface of the glass substrate very strongly by the action of the coupling agent. In general, a coupling agent is a substance in which a hydrophilic group and a hydrophobic group are bonded to a metal atom such as silicon, and the hydrophilic group chemically bonds to the glass substrate through the action on the glass substrate surface, and the hydrophobic group forms a photoresist. By facing the layer, it functions to increase the adhesion between the glass substrate and the photoresist layer. That is, usually, adsorbed water is present on the surface of an oxide such as a glass substrate, and a hydroxyl group generated by dissociation of the adsorbed water is bonded to a silicon atom. When, for example, an alkoxide-type coupling agent molecule approaches such a glass substrate, an oxygen atom of the alkoxy group reacts with an active hydrogen atom of a hydroxyl group on the surface of the glass substrate. Then, the alkoxy group is bonded to the active hydrogen atom and removed as an alcohol, and the metal atom in the coupling agent molecule is directly bonded to the oxygen atom of the hydroxyl group. As a result, a hydrophobic group is introduced into the surface of the glass substrate through the bond between the metal atom and the oxygen atom, and the affinity with the photoresist layer is improved.

Finally, in step S7, the photoresist layer is exposed and developed to complete a glass master for an optical disk. Specifically, the photoresist layer is selectively exposed or cut by a laser beam in accordance with an uneven pattern such as pits or grooves representing information to be recorded. Thereafter, the exposed portion (in the case of a positive photoresist) or the non-exposed portion (in the case of a negative photoresist) of the photoresist layer is removed by a developing process.

Next, a specific example of the surface treatment method for a glass substrate according to the present invention will be described in detail. FIG. 2 is a schematic diagram showing a precision parts washing machine W used for carrying out the present method. The washing machine W has a washing room isolated from the outside air, and the inside is filled with clean air containing no dust or the like. A total of six bathtubs B1 to B6 are provided in the room. Each bathtub is equipped with an ultrasonic oscillator as needed. The solution held in the bath is circulated through a filter to maintain cleanliness. A heater with temperature control is incorporated in the circulation path to control the bathtub temperature to a desired value. In addition, a transfer mechanism is incorporated in the room, and the objects to be processed are sequentially transferred from the bathtub to the bathtub.

Using the precision parts washing machine W, a glass substrate is subjected to a coupling agent treatment. The processing conditions are shown in Table 1 below.

[Table 1]

The bathtub B1 is filled with pure water (PW) having a specific resistance of, for example, 16 MΩ. The bath temperature is 2
It is controlled at 2 ° C ± 1 ° C. The glass substrate is immersed in the bath B1 for 3 minutes, and pre-cleaning is performed by applying ultrasonic waves.

The second bath B2 is filled with a silane coupling agent aqueous solution (silane). As the silane coupling agent, for example, Shin-Etsu Chemical Co., Ltd. KBM-403
Γ-glycidoxypropyltrimethoxysilane represented by the following chemical formula 1 and available from Nihon Unicar Co., Ltd.
Γ shown in the following chemical formula 2, available as A-1100
Using aminopropyltriethoxysilane.

Embedded image

[0022]

Embedded image NH ₂ —CH ₂ CH ₂ CH ₂ Si (OC ₂ H ₅ ) _{3 The} above silane coupling agent is dissolved in pure water to give a concentration of 1
A silane coupling agent aqueous solution of ± 0.1 wt% is prepared. The glass substrate is immersed in the bath B2 for 3 minutes to perform a surface treatment.

The third bath B3 has a specific resistance of 18 MΩ.
Degree of pure water is filled. The bath temperature is 22 ℃ ±
It is set at 1 ° C. The surface-treated glass substrate is immersed in this bath for 3 minutes to remove excess silane coupling agent.

The fourth bath B4 is filled with isopropyl alcohol or IPA maintained at 18 ° C. ± 1 ° C. The glass substrate is immersed in this for 3 minutes, and ultrasonic waves are applied to perform cleaning. The fifth bathtub B5 is also the fourth bathtub B
It has the same configuration as that of No. 4, and the cleaning is repeated.

The last bath B6 is filled with isopropyl alcohol kept at 18 ° C. ± 1 ° C. This IP
A has a grade specified as a chemical for electronic industry. After immersing the glass substrate GS in the bath B6, the glass substrate GS is slowly pulled up at a speed of, for example, 2 mm / sec and dried. By this lifting and drying, a glass substrate having a clean surface state and preserving the original adhesion performance of the silane coupling agent can be obtained.

[0026]

As described above, according to the present invention, since the surface treatment of a glass substrate is performed using a precision parts washing machine using a silane coupling agent diluted with a large excess of water, for example, In addition, there is an effect that a film of a coupling agent having few defects can be formed. Further, since the glass substrate is pulled up and dried in a relatively low temperature region near room temperature, there is an effect that there is no deterioration of the coupling agent film and an extremely strong adhesion to the photoresist layer can be obtained. Further, by performing baking of the glass substrate after drying at a low temperature, there is an effect that the adhesion strength can be further improved.

[Brief description of the drawings]

FIG. 1 is a process chart showing a surface treatment method for a glass substrate.

FIG. 2 is a schematic block diagram showing a precision component washing machine used for surface treatment of a glass substrate.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C03C 15/00-23/00 G11B 7/26

Claims (1)

(57) [Claims] Line to a surface treatment using a 1. A coupling agent
Of the glass substrate on which the photoresist layer is formed
In the surface treatment method, the surface-treated glass substrate is subjected to isothermal treatment at 15 ° C. to 70 ° C.
A surface treatment method for a glass substrate, wherein the glass substrate is pulled up from propyl alcohol or pure water at 15 ° C to 60 ° C and dried.