JPH06150397A - Production of optical master disk - Google Patents

Abstract

PURPOSE:To provide a good optical master disk by applying a first photoresist layer on a substrate and applying a second photoresist layer in superposition on this first photoresist layer at the time of a photoresist applying stage. CONSTITUTION:The photoresist layer 2 is first applied on a base material 1 by using a spin coating method, etc. The photoresist having the sensitivity higher than the sensitivity of the photoresist of the photoresist layer 2 is then used and is applied in superposition on the photoresist layer 2 to form the photoresist layer 3. Recording light 5 is adjusted to the intensity at which both layers of the photoresist layer 2 and the photoresist layer 3 can be sufficiently exposed and recording light 6 is adjusted to the intensity at which only the photoresist layer 3 is exposed. Information is recorded concentrically or spirally on a substrate in such a manner that the arrays of recorded pits 8 recorded by the recording light 5 are adjacent to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk master.

[0002]

2. Description of the Related Art Conventional optical disk masters (hereinafter simply referred to as masters) have the same depth of pits formed on the surface thereof. However, as a method for increasing information density, A master in which pits having different depths are formed on the same master has been proposed (for example, Japanese Patent Laid-Open No. Sho 5).
4-136303). However, it has been difficult to manufacture this master by the conventional master manufacturing method.

A conventional master manufacturing method will be described with reference to FIG. A photoresist is applied onto the substrate 1 by a spin coating method or the like (FIG. 3b). Next, the laser light 13 is passed through the lens 12
The information is recorded on the substrate in a concentric or spiral manner by exposing the photoresist 11 by squeezing (FIG. 3c). The developing solution 15 is brought into contact with the photoresist on the exposed substrate (FIG. 3d), and the manufacturing process is finished (FIG. 3e).

[0004]

In the conventional manufacturing method, since the pit depth on the master is determined by the film thickness of the photoresist formed on the substrate, the pit depth is the same on all masters. It was impossible to change the pit depth on the same master. This manufacturing method is a manufacturing method aiming at eliminating the above-mentioned drawbacks.

[0005]

In order to achieve this object, the present invention uses the following means. (1) In a master disc manufacturing method including a step of applying a photoresist on a substrate, a recording (exposure) step, and a developing step, a first photoresist layer is formed on the substrate during the photoresist applying step on the substrate. And a second photoresist layer overlaid on the first photoresist layer, and a recording light of an intensity that exposes only the second photoresist layer during the recording step, and the second photoresist. Recording is done with recording light of an intensity that exposes the layer and the first photoresist layer. (2) In a master disc manufacturing method including a step of applying a photoresist on a base material, a recording (exposure) step, and a developing step, a first photoresist layer is formed on the base material during the photoresist applying step on the base material. Is applied, and a second photoresist layer having a longer absorption edge wavelength than that of the first photoresist layer is overlaid on the first photoresist layer, and only the second photoresist layer is applied during the recording step. Recording is performed by using recording light having a wavelength of exposing light and recording light having a wavelength of exposing the second photoresist layer and the first photoresist layer. (3) In a master disc manufacturing method comprising a step of applying a photoresist on a substrate, a recording (exposure) step, and a developing step, a first photoresist layer is formed on the substrate during the photoresist applying step on the substrate. Strength to form a boundary layer on the first photoresist layer, apply a second photoresist layer over the boundary layer, and expose only the second photoresist layer during the recording process. Recording is performed by using the recording light of (1) and the recording light having an intensity that exposes the second photoresist layer and the first photoresist layer. (4) In a master disc manufacturing method comprising a step of applying a photoresist on a base material, a recording (exposure) step, and a developing step, a first photoresist layer is formed on the base material during the photoresist applying step on the base material. Is applied, a boundary layer is formed on the first photoresist layer, and a second photoresist layer having an absorption edge wavelength longer than that of the first photoresist layer is applied on top of the boundary layer for recording. Recording is performed using recording light having a wavelength that exposes only the second photoresist layer and recording light having a wavelength that exposes the second photoresist layer and the first photoresist layer during the process.

[0006]

By using the above-mentioned means, the pits recorded with the recording light having the intensity enough to expose only the second photoresist layer have only the second photoresist layer developed by the developing process, and the second photoresist layer is developed. It becomes a pit whose depth is the thickness of the resist layer. The pits recorded by the recording light having an intensity sufficient to expose both the second photoresist layer and the first photoresist layer are processed by the same process as in the second photoresist layer and the first photoresist layer. The pits have a depth that is the sum of the film thicknesses (or the thickness of the boundary layer if there is a boundary layer), and pits with different depths can be obtained on the same master.

Further, a second photoresist layer having an absorption edge wavelength longer than that of the first photoresist layer is used, and a second recording light having a wavelength for exposing only the second photoresist layer is used. Even when recording is performed using the first recording light having a wavelength for exposing both the photoresist layer and the second photoresist layer, pits having different depths are similarly obtained on the same master.

The boundary layer formed between the first photoresist layer and the second photoresist layer prevents the recording light during recording on the second photoresist layer from exposing the first photoresist layer. At the same time as preventing, the shape of the bottom surface of the pit recorded in the second photoresist layer is flattened to improve the pit shape.

[0009]

【Example】

(Embodiment 1) A first embodiment of the method for manufacturing a master according to the present invention will be described with reference to FIG.

First, a photoresist layer 2 is applied onto a substrate 1 by using a spin coating method or the like (FIG. 1a). Next, a photoresist having a sensitivity higher than that of the photoresist of the photoresist layer 2 is used, and the photoresist layer 3 is overlaid and applied to form the photoresist layer 3 (FIG. 1b).

The recording light 5 has an intensity sufficient to expose both the photoresist layer 2 and the photoresist layer 3, and the recording light 6
Is such that only the photoresist layer 3 is exposed, and information is concentrically or spirally formed on the substrate so that the row of pits 7 recorded by the recording light 5 and the row of pits 8 recorded by the recording light 6 are adjacent to each other. Record (Fig. 1c). Since the photoresist layer 2 has a lower sensitivity than the photoresist layer 3, when recording is performed on the photoresist layer 3 by the recording light 6, the photoresist layer 2 below the photoresist layer 2 is not exposed.

The substrate is developed and the master manufacturing process is completed (FIG. 1d). Through the above steps, the photoresist layer 2
And a row of pits 7 whose pit depth is the sum of the thicknesses of the photoresist layer 3 and the photoresist layer 3
It is possible to form pits having different depths in the row of pits 8 with the thickness of pit as the pit depth on the master.

The photoresist layer 3 having a longer absorption edge wavelength than that of the photoresist layer 2 is similarly applied, and the recording light 6 having a wavelength for exposing only the photoresist layer 3 is used.
Then, recording may be performed in the same manner by using the recording light 5 having a wavelength that exposes both the photoresist layer 2 and the photoresist layer 3. Since the recording light 6 has a long wavelength to expose the photoresist layer 2, the photoresist layer 2 is not exposed when recording on the photoresist layer 3.

The photoresist layer 2 is baked,
The photoresist layer 3 may not be baked, so that the sensitivity of the photoresist layer 2 may be lower than that of the photoresist layer 3.

(Embodiment 2) Second embodiment of master disk manufacturing method of the present invention
The embodiment will be described with reference to FIG.

First, the photoresist layer 2 is applied onto the substrate 1 by using a spin coating method or the like (FIG. 2a). Next, CEL is applied over the photoresist layer 2 to form the boundary layer 4 (FIG. 2b). Then, a photoresist layer 3 is applied on the boundary layer 4 (FIG. 2c). Since CEL has a much higher absorbance than photoresist and the photobleaching due to exposure is non-linear with respect to the exposure amount, it enhances the contrast of the exposure image incident on the photoresist layer 2 below the CEL layer.

The recording light 5 has an intensity sufficient to expose both the photoresist layer 2 and the photoresist layer 3, and the recording light 6
Is such that only the photoresist layer 3 is exposed to light, and information is concentrically or spirally formed on the substrate so that the row of pits 9 recorded by the recording light 5 and the row of pits 10 recorded by the recording light 6 are adjacent to each other. Record (Fig. 2d).
When recording with the recording light 6, the recording light 6 is blocked by the boundary layer 4 and thus the photoresist layer 2 is not exposed. The pit shape of the row of pits 10 also has a flat and good bottom surface with the boundary layer 4 as the bottom.

Finally, the substrate is developed to complete the master disc manufacturing process. If a water-soluble CEL (for example, manufactured by GE) is used, the CEL between the exposed photoresists is increased.
Also, since this developing step melts together with the photoresist, the step of removing the CEL can be omitted.

In addition, when the photoresist layer 2 is applied, the substrate is baked (for example, in an atmosphere containing at least one of nitrogen, oxygen, argon, and krypton).
30 minutes at 0 ° C.) to form an altered layer on the surface of the photoresist layer 2, and this altered layer is replaced by the boundary layer 4 instead of CEL.
You may use as.

At the stage where the photoresist layer 2 is applied, the substrate may be subjected to development treatment to form an altered layer on the surface of the photoresist layer 2, and this altered layer may be used as the boundary layer 4 instead of the CEL.

The photoresist layer 3 is formed on the photoresist layer 2.
One having a lower sensitivity may be used.

The photoresist layer 2 is baked,
The photoresist layer 3 may not be baked, so that the sensitivity of the photoresist layer 2 may be lower than that of the photoresist layer 3.

The photoresist layer 2 is formed on the photoresist layer 3.
Recording light 6 having a wavelength that exposes only the photoresist layer 3 and recording light having a wavelength that exposes both of the photoresist layer 2 and the photoresist layer 3 by applying the same material having a long absorption edge wavelength. 5 may be used for similar recording.

[0024]

As described above, according to the optical disc master manufacturing method of the present invention, a good optical disc master having pit rows having different depths in the same master can be obtained.

[Brief description of drawings]

FIG. 1 is a process chart of an embodiment of a method for manufacturing an optical disc master according to the present invention.

FIG. 2 is a process chart of another embodiment of the method for manufacturing an optical disk master according to the present invention.

FIG. 3 is a process diagram of a conventional optical disc master manufacturing method.

[Explanation of symbols]

 1 Base Material 2 Photoresist Layer 3 Photoresist Layer 4 Boundary Layer 5 Recording Light 6 Recording Light 7 Pit 8 Pit 9 Pit 10 Pit 11 Photoresist 12 Lens 13 Laser Light 14 Exposed Photoresist 15 Developer

Front Page Continuation (72) Kenji Takamoto, 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. ) Inventor Shinya Abe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (10)

[Claims] 1. A method for producing an optical disk master, which comprises a step of applying a photoresist onto a substrate, a recording (exposure) step, and a developing step. A photoresist layer is applied, a second photoresist layer is applied on top of the first photoresist layer, and both the first photoresist layer and the second photoresist layer are exposed during the recording process. To form pits having different depths on the same master by recording and developing using a first recording light having an intensity of a certain intensity and a second recording light having an intensity of exposing only a second photoresist layer. And a method for manufacturing an optical disc master. 2. A method for producing an optical disk master, which comprises a step of applying a photoresist onto a substrate, a recording (exposure) step, and a developing step, wherein the first step of applying the photoresist onto the substrate is performed. A photoresist layer is applied, and a second photoresist layer having an absorption edge wavelength longer than that of the first photoresist layer is applied on top of the first photoresist layer, and the first photoresist is applied during the recording process. By recording and developing using a first recording light having a wavelength that exposes both the layer and the second photoresist layer and a second recording light having a wavelength that exposes only the second photoresist layer, A method for manufacturing an optical disk master, comprising forming pits having different depths on the same master. 3. A method of manufacturing an optical disk master comprising a step of applying a photoresist onto a substrate, a recording (exposure) step, and a developing step. A photoresist layer is applied, a boundary layer is formed on the first photoresist layer, a second photoresist layer is overlaid on the boundary layer, and the first photoresist layer and the second photoresist layer are applied during the recording process. On the same master by recording and developing using a first recording light having an intensity exposing both layers of the second photoresist layer and a second recording light having an intensity exposing only the second photoresist layer. A method for manufacturing an optical disk master, characterized in that pits having different depths are formed on the substrate. 4. A method for manufacturing an optical disk master, which comprises a step of applying a photoresist onto a substrate, a recording (exposure) step, and a developing step. A photoresist layer is applied, a boundary layer is formed on the first photoresist layer, and a second photoresist layer having a longer absorption edge wavelength than the first photoresist layer is applied on the boundary layer. Then, the first recording light of a wavelength that exposes both the first photoresist layer and the second photoresist layer during the recording step, and the second recording light of a wavelength that exposes only the second photoresist layer. Recorded using
A method for manufacturing an optical disc master, characterized in that pits having different depths are formed on the same master by developing. 5. The method of manufacturing an optical disk master according to claim 3, wherein an altered layer formed on the surface of the first photoresist layer by baking the first photoresist layer is used as a boundary layer. 6. The method according to claim 5, wherein the first photoresist layer is baked in an atmosphere containing at least one of nitrogen, oxygen argon and krypton. 7. The method of manufacturing an optical disk master according to claim 3, wherein an altered layer formed on the surface of the first photoresist layer by developing the first photoresist layer is used as a boundary layer. 8. The method according to claim 3, wherein CEL is used for the boundary layer.
A method for manufacturing an optical disc master described in the above. 9. The method of manufacturing an optical disk master according to claim 1, wherein a first photoresist layer having a lower sensitivity than that of the second photoresist layer is used. 10. The method according to claim 1, wherein the first photoresist layer is baked and the second photoresist layer is not baked.