JPS6023407B2 - Method for manufacturing information recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an information recording medium having an information track on a substrate, and in particular having an audio and/or video information track in the form of bits or blocks,
The present invention provides an optimal method for applying this recorded information to a disk recorder in which the recorded information is written and read by an optical system.

Stamp bars are obtained from this type of recording disc by a method such as plating, and these stamp bars are sequentially transferred to produce a large number of press-molded video discs.

For example, after a Cr layer is deposited on a glass slope, a positive type photoresist layer such as AZ-1350 is applied to the surface of this Cr layer, and this photoresist layer is cut with a laser beam or ultraviolet rays for cutting. Selective exposure is performed along a portion corresponding to the information track.

Thereafter, the exposed portion of the photoresist layer is removed by a development process, the Cr layer exposed in the removed portion is etched away, and finally the photoresist layer is removed to leave a predetermined pattern of the Cr layer. However, the inventor of the present invention discovered that due to excessive use of this method, the abnormal phenomenon described below occurs.
It was discovered that only a Cr layer having a pattern opposite to the desired pattern could be obtained.

That is, as shown in FIG. IA, a C layer 2 and a photoresist layer 3 are sequentially laminated on a glass plate 1 and irradiated with a laser beam 4, and then, after development, a Sekiguchi layer 5 is formed on the photoresist layer 3 as shown in FIG. IB. However, the next etching process
C below Sekiguchi 5, which should normally be etched as shown in the figure.
The r layer remains, and conversely, the Cr layer under the photoresist layer 3 is over-etched by the etching solution penetrating from the side, and as the etching progresses further, it is completely etched away. Therefore, when the photoresist layer 3 is removed, the Cr layer 2 is exposed to the laser beam 4 as shown in FIG.
As a result, a negative pattern opposite to the predetermined pattern remains. The cause of this abnormal phenomenon is that a strong oxide film (which cannot be dissolved in organic solvents such as acetone) is formed on the surface of the Cr in the irradiated area due to the heat generated by the laser beam 4, or that the photoresist is coated on the surface of the Cr. This is probably due to burn-in, or worse, because both of these were repaired together. In either case, it can be considered that some kind of etching-resistant mask was formed on the surface of the Cr layer by the laser light irradiation. The present invention was invented based on the discovery of the above-mentioned abnormal phenomenon, and includes a method for manufacturing an information recording medium in which an information track is provided on a base, which further comprises forming a metal layer on the base, and furthermore, forming a metal layer on the base. A photoresist layer is formed on the layer, and then a laser beam is selectively irradiated onto the photoresist layer along the portion corresponding to the information track, and the metal layer corresponding to the irradiated portion is heated by the irradiation to form the photoresist layer. react with the resist layer,
Information characterized in that an etching-resistant portion is formed on the surface of the metal layer by this reaction, and after the photoresist layer is removed, the metal layer is selectively etched using the etching-resistant portion as a mask. This relates to a method for manufacturing a recording medium.

By this method, it is possible to obtain a desired pattern of information tracks, a pattern with high resolution, and at the same time it is possible to significantly simplify the process. Next, an embodiment in which the present invention is applied to a video disk recording disk is shown in FIGS.
This will be explained with reference to Figure 5. First, as shown in FIG. 2A, a Cr layer 12 is deposited to a thickness of 1000 to 1500 Å on a glass plate 1, and a positive photoresist layer made of AZ-1350 (manufactured by Shipley) is further formed on this Cr layer. 1
Apply 3.

In this state, the photoresist layer 13 is selectively irradiated with a laser beam 14 having a power of 0.5 or more using an apparatus to be described later. As a result, on the surface of the Cr layer 12 existing in the area irradiated with the laser beam 14, a white brim, an etching-resistant mask layer 16, which is thought to be made of the aforementioned oxide or a frosted photoresist, is formed as shown in FIG. 2B. Ru.

After completing the process shown in FIG. 2A, the photoresist layer 13 is not developed as in the conventional method, but is immediately dissolved and removed in its entirety with acetone to form the state shown in FIG. 2B. Next, by etching the Cr layer 12 between the mask layers using the masking effect of the mask layer 16, the Cr layer 12 can be left only under the mask layer 16, as shown in FIG. 2C, and a predetermined pattern (in this case A negative pattern) information track is formed. According to this embodiment, since the mask layer 16 is in very strong contact with the Cr layer 12, the Cr below the mask layer 16 is not easily etched, while the Cr between the mask layers 16 is not easily etched.
is easily etched, and it is very easy to determine the etching conditions.

For this reason, the Cr under the mask layer 16 is unlikely to be over-etched, which has the advantage that a high-resolution pattern can be accurately and easily obtained. Note that the Cr layer 12
is very thin, so even if over-etching occurs, it is hardly a problem. However, what is obtained is a negative pattern, so the pattern does not become larger than necessary. Further, since the photoresist layer 13 is removed as it is without being developed as in the conventional method, the developing step can be omitted. Furthermore, even if a photoresist is used, it is not used as an etching mask as in the past, so light-shielding equipment such as a yellow room is not required, and the process can be further simplified. The mechanism by which the mask layer 16 as described above is formed will be explained with reference to FIGS. 3 and 4.

For comparison, when the photoresist layer 13 is directly coated and formed on the glass plate 11 as shown in FIG. 3A, the laser beam 1
After irradiation with step 4, this was developed to form a closed opening 15 as shown in FIG.
The result was obtained as shown in Figure C. Next, as in this embodiment, the glass plate 1
When a Cr layer 12 and a photoresist layer 13 were laminated on top of the Cr layer 12 and a photoresist layer 13 were irradiated with laser light, an SEM photograph (scanning electron microscope photograph) after the irradiation showed that the photo of the exposed portion was as shown in Fig. 4. The resist layer 13 swells to form a cavity 1 inside.
It was found that 7 was formed. This is because the heat of the laser beam causes the photoresist and Cr to become gaseous (for example, N
It is considered that a reaction accompanied by the occurrence of 2) occurred, and a cavity 17 was formed by this gas, and a strong mask such as Cr oxide was formed on the surface of Cr. However, as described above, when the base of the photoresist layer 13 is a glass plate, there is no apparent change in the photoresist layer 13 even if it is exposed under the same appropriate exposure conditions, and a latent image is recorded. Incidentally, an apparatus for performing the above-mentioned cutting is shown in FIG.

The glass plate 11 in the state shown in FIG. 2A is connected to the rotating shaft of the electric motor 18 so as to be rotatable, and the photoresist layer 13 side of the glass plate 11 has a dust cover having a gate 19 in the radial direction of the glass plate 11. 20 is placed nearby. This Sekiguchi 19
Inside is an air bearing head 2 fixed to a moving table 21.
2, and an objective lens (not shown) close to the glass plate 11 is held in position by an air bearing. To expose the photoresist layer 13, the laser light 14 from the Ar laser 23 is modulated by the electric shirt 24, and then the prism 25, lens 26, and dichroic mirror 27 are used.
, and are guided to the objective lens of the head 22 by a mirror 28 and guided to a predetermined position on the glass plate 11.

At this time, if the glass plate 11 is rotated by the electric motor 18 and the moving stage 21 is moved at a constant speed, the photoresist layer 1
3 exposures can be performed in a spiral manner. In order to carry out the monitoring, the laser beam 30 from the He-Ne laser 29 is guided to the lens 32 by the mirror 31, and is reflected by the mirrors 33, 27, 28' respectively. Cr layer 12. The tracking transducer 31 can detect reflected light from the cut surface. Note that the focus of each laser beam can be adjusted by moving the lenses 26 and 32. Although the present invention has been described above based on implementation, it will be understood that further modifications can be made based on the technical idea of the present invention.

For example, in addition to the glass plate 11, a substrate made of metal, polymer, etc. can be used, and in addition to the Cr layer 12, Ni, Fe, T, etc. can be used.
It is also possible to use a metal layer such as i, which is easy to form an oxide film and has good adhesion to the substrate.

Note that the information track may have a circular shape instead of a spiral shape, and it is also possible to use a recording medium such as a cylindrical shape instead of a disk recording disk. As described above, the present invention involves forming a metal layer on a substrate, further forming a photoresist layer on this metal layer, and causing the metal layer corresponding to the irradiated portion to react with the photoresist layer by heating by laser beam irradiation. This reaction forms an etching-resistant part on the surface of the metal layer, and after removing the photoresist layer, the metal layer is selectively etched using the etching-resistant part as a mask. A layer remains and a negative information recording pattern can be obtained.

However, in this case, since the mask layer on the surface of the metal layer is in strong contact with the metal layer, the metal under the mask layer is unlikely to be over-etched, so the etching conditions are easy and extremely high-resolution patterns can be formed accurately and easily. It can be formed into

Further, unlike the conventional method, a photoresist is not used as an etching mask, and development processing is no longer necessary, so the manufacturing process can be significantly simplified.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a conventional method for manufacturing a video disc master in the order of steps. 2 to 5 show an embodiment in which the present invention is applied to a method for manufacturing a video disc master, and FIGS.
Figure C is a cross-sectional view showing the method in the order of steps, Figures 3A to * are cross-sectional views showing the state when photoresist is directly applied on the glass slope, exposed and etched, and Figure 4 is a cross-sectional view showing the method in this example. FIG. 5 is a cross-sectional view showing the state when heated by light irradiation, and a schematic diagram of an apparatus for cutting with laser light. In the reference numerals used in the drawings, 11 is a glass plate, 12 is a Cr layer, 13 is a photoresist layer, 14 is a laser beam, and 16 is a mask layer. Figure IA Figure IB Figure IC Figure ID Figure 2A Figure 2B Figure 2C Figure 3A Figure 38 Figure 3C Figure 4 Figure 5

Claims (1)

[Claims] 1. In a method for manufacturing an information recording medium in which an information track is provided on a substrate, a metal layer is formed on the information track, a photoresist layer is further formed on this metal layer, and then a photoresist layer is formed along a portion corresponding to the information track. The photoresist layer is selectively irradiated with laser light, and the metal layer corresponding to the irradiated area is heated by the irradiation to react with the photoresist layer, and this reaction causes the surface of the metal layer to become resistant. A method for manufacturing an information recording medium, characterized in that after forming an etching portion and removing the photoresist layer, the metal layer is selectively etched using the etching resistant portion as a mask.