JP2001344831A - Information recording medium master disk and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable method for manufacturing a master disk by which deactivation of a photoresist by intrusion of a base material is suppressed even when a substrate containing a base material is used in the method for the manufacture of an information recording medium which uses a chemically amplifying photoresist. SOLUTION: A non-basic and almost transparent barrier layer 102 which prevents intrusion of a base material is formed between the substrate containing a base and the chemically amplifying photoresist film used as a photosensitive material so as to isolate the photoresist film 103 from diffusion of the base material in the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a master for an information recording medium such as an optical disk, and more particularly to a method for producing a chemically amplified photoresist as a photosensitive material.

[0002]

2. Description of the Related Art With the spread of compact discs (CDs), optical discs have become common. However, research and development of higher density optical discs have been actively carried out. Has been proposed and put into practical use. In the future, development of a further high-density optical disk for recording a signal requiring a large capacity such as a high-definition television at a high density is desired. For that purpose, a technique for producing a high-density information recording medium master capable of finer recording is very important.

As shown in FIG. 2, a conventional information recording medium master is formed by applying a photoresist mainly composed of a novolak resin to a soda glass substrate 201 by a spin coating method to form a photoresist film 202. A recording step of modulating or deflecting blue light (for example, wavelength 458 nm) or near-ultraviolet light (for example, wavelength 351 nm) according to a signal to be recorded, condensing and exposing with an objective lens 203, and then developing and exposing It is manufactured by a developing step of forming a pattern or a groove called a pit by removing 204.

In order to increase the recording density, it is necessary to form smaller pits and narrow grooves. For example, in a DVD having a capacity of 4.7 GB, the minimum pit size is about 0.4 μm in length and about 0.3 μm in width, and to achieve a capacity of about 25 GB, the length is 0.18 μm in width and about 0.18 μm in width. 0.15μ
It is necessary to form about m pits. The size of the formed pit depends on the diameter of the focused spot of the recording light, and a smaller focused spot diameter is required to form a smaller pit.

In general, the diameter of a focused spot is proportional to the wavelength of recording light and inversely proportional to the numerical aperture. However, in terms of the numerical aperture, the light has been condensed using an objective lens of 0.9 or more, and it is difficult to further increase it. Therefore, an attempt has been made to use far ultraviolet light having a wavelength shorter than 300 nm as recording light and to reduce the focused spot diameter by shortening the wavelength.

[0006]

However, a photoresist mainly composed of novolak resin, which has been conventionally used, shows a large absorption in this wavelength range, and the light energy is absorbed by the absorption rather than the photosensitive process which should occur originally. The process of converting into thermal energy, raising the temperature, and altering the properties is dominant, and the function as a photoresist is lost, so that application in this wavelength range is difficult.

Therefore, application of a chemically amplified photoresist mainly containing polyvinyl phenol (PVP), polymethyl methacrylate (PMMA), or the like prepared for a deep ultraviolet excimer laser has been attempted. However, in the conventional novolak resin photoresist, a solubilization reaction in an alkaline developer proceeds according to the energy of the exposed light, but in a chemically amplified photoresist,
Protons (acids) generated by the energy of the exposed light act as catalysts to promote the solubilization in an alkaline developer by baking after exposure, and the final shape after development is determined.

Therefore, when a base substance enters, the generated protons are trapped and deactivated by the neutralization reaction, do not function as a catalyst, and have the same effect as a change in the sensitivity of the photoresist as a result. The shape formed by development changes. Therefore, soda glass, which has been conventionally used as a base material, itself contains a basic substance, and when directly applied, is diffused into a photoresist and similarly causes deactivation of protons. Further, it is necessary to control the concentration of the base substance present in the atmosphere.

Further, since the exposure is performed sequentially from the inner circumference to the outer circumference or from the outer circumference to the inner circumference, a time difference occurs between the start and end of the exposure. The change in sensitivity during that time causes unevenness in the shape after development, and thus poses a serious problem as an information recording medium master.

Therefore, an object of the present invention is to prevent the inactivation of the photoresist by blocking the base substance that diffuses and invades the chemically amplified photoresist from the substrate, even if conventional inexpensive soda glass is used as the substrate. Accordingly, an object of the present invention is to provide a method for stably producing an information recording medium master.

[0011]

According to the present invention, there is provided a method for producing a master for an information recording medium, wherein a base material is present between a base material and a chemically amplified photoresist film used as a photosensitive material even if the base material contains the base material. By providing a layer of a non-basic material that blocks the diffusion and invasion of the base material, it is possible to prevent a base substance from invading from the base material and deactivating the chemically amplified photoresist. Also, by forming a protective film of a non-basic material on the surface of the photoresist film, it is possible to prevent a base substance in the atmosphere from invading the photoresist and to obtain an effect of preventing deactivation. Here, the non-basic material means a material that does not diffuse a base material into a photoresist film and does not react with a photoresist or a thinner to generate a base material.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for producing an information recording medium master according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a method for producing an information recording medium master according to an embodiment of the present invention. First, as a film forming process, a soda glass substrate 1 whose surface has been cleaned
A transparent isolation layer 102 made of silicon dioxide is formed on the substrate 01 by a chemical vapor deposition method (CVD method). As a coating step, a PVP-based chemically amplified photoresist is applied by a spin coating method, and the thinner is sufficiently evaporated by heating to form a photoresist film 103 having a thickness of about 70 nm.

In the protective film forming step, a water-soluble polyvinyl-based polymer (for example, TSP-5A manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a non-basic material, is applied by spin coating and dried to form the protective film 104. The water-soluble polyvinyl polymer itself does not contain a base and does not react with a resist or a substance in the atmosphere to generate a base.

The thickness of the protective film 104 is adjusted to 300 nm in accordance with the thickness of the applied photoresist film so as to be within the focal depth where the recording light is condensed in a later recording step.
It is desirable to do the following. The protective film 104 isolates the photoresist film 103 from the external atmosphere, and prevents a base substance in the atmosphere from entering the photoresist film 103.

The silicon dioxide using the transparent isolation layer 102 is a covalent bond of oxygen and silicon, does not contain a base,
Further, it does not react with the photoresist or its thinner to produce a base. Therefore, the soda glass substrate 101
Prevents the base substance from diffusing and entering the photoresist film 103.

The thickness of the transparent isolation layer 102 is determined in consideration of the refractive index of the soda glass substrate 101 with respect to the recording wavelength in the subsequent recording step, and the respective refractive indices and thicknesses of the protective film and the photoresist. It is desirable to set so that the reflectance of the recording light becomes small.

Next, a deep ultraviolet laser (wavelength: 248 nm) using the second harmonic of an argon ion laser modulated or deflected according to a signal to be recorded is collected by the objective lens 105 through the protective film 103 as a recording step. Light and expose. Before the recording step, it is desirable to perform a heat treatment again to diffuse the protons in the photoresist to make the concentration distribution uniform.

After the recording step, as a heat treatment step, the generated proton is used as a catalyst to accelerate the alkali solubilization reaction of the photoresist. Next, as a protective film removing step, pure water is applied while rotating the base material to dissolve and remove the water-soluble protective film. Then, as a developing step, the exposed portion 106 is dissolved and removed with an alkaline developer while rotating the substrate, and the developer is rinsed again with pure water to wash off the developer, and then rotated and shaken off to dry the pit pattern. To produce an information recording medium master having

In this embodiment, silicon dioxide is used as the material of the transparent isolation layer. However, even in the case of an inorganic material of a non-basic covalent bond such as aluminum oxide, it reacts with a photoresist or a thinner to convert a basic substance. If not,
A similar effect can be obtained when used as a material for the transparent isolation layer. A similar effect can also be obtained with an organic polymer of a water-insoluble material that does not generate a base substance by reacting with a photoresist or a thinner (for example, AR2 manufactured by Shipley).

[0021]

According to the method for producing an information recording medium master of the present invention, even when a chemically amplified photoresist is used, it is possible to prevent a base substance from entering the photoresist from the substrate and deactivating the photoresist. As a result, variations in the shape of each master are suppressed, and variations in the shape within each master are also suppressed, so that a stable information recording medium master can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a method for producing an information recording medium master according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a conventional method for producing a master of an information recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Quartz glass base material 102 Transparent isolation layer 103 Photoresist film 104 Protective film 105 Objective lens 106 Exposure part 201 Soda glass base material 202 Photoresist film 203 Objective lens 204 Exposure part

Claims (10)

[Claims] 1. An information recording medium master in which a non-basic material film is laminated on a base material, and a desired pattern is formed on the non-basic material film by a chemically amplified photoresist resin. 2. The information recording medium master according to claim 1, wherein the base material is a material containing a basic substance or soda glass. 3. The information recording medium master according to claim 1, wherein the non-basic material is silicon dioxide. 4. The information recording medium master according to claim 1, wherein the non-basic material is aluminum oxide. 5. The information recording medium master according to claim 1, wherein the non-basic material is a water-insoluble organic polymer. 6. A film forming step of forming a film of a non-basic material on a substrate, a coating step of applying a chemically amplified photoresist as a photosensitive material and drying by heating, and a recording light having a wavelength of 300 nm or less. A recording step of condensing and exposing by modulating or deflecting according to a signal to be recorded, and a heat treatment step after exposure,
A method for producing an information recording medium master comprising a developing step of developing the chemically amplified photoresist to form a desired pattern. 7. The method according to claim 6, wherein the non-basic material is substantially transparent to the wavelength of the recording light. 8. After the coating step, a protective film forming step of forming a water-soluble material substantially transparent to the wavelength of the recording light to a thickness of 300 nm or less is performed. 7. The method according to claim 6, wherein the developing step is performed after the protective film removing step for removing the water-soluble material. 9. The method according to claim 8, wherein the water-soluble material is an organic polymer. 10. The method according to claim 8, wherein a heat treatment is performed between the step of applying the water-soluble material and the step of recording.